Trichinella and Trichinellosis

By Fabrizio Bruschi

Trichinella and Trichinellosis provides an up-to-date account of the nematode Trichinella spp., including infections and diseases caused by this parasite in both animals and humans. This book will fill the long gap in time during which an exhaustive monograph on this subject has been missing in the international literature. The chapters have been written by the most prolific researchers in the world on the different aspects of Trichinella and trichinellosis.

This book serves as an original resource for research on Trichinella and trichinellosis, exploring cutting-edge advances on such parasites and the infections they cause.

This book will be a valuable resource for students, biologists, epidemiologists, veterinarians, physicians, and scientists involved in the study of the parasites of the Trichinella genus and their related diseases. It will be particularly helpful for those who are beginning their research in this fascinating field.

• Offers a broad overview on the parasites belonging to the Trichinella genus
• Presents recent cutting-edge advances on this zoonotic parasite, focusing on the molecular epidemiology, systematics of the parasite, clinical aspects of the diseases, and the roadmap to the control of infection in domestic pigs
• Discusses ground-breaking approaches designed to meet the medical needs in trichinellosis

• Language: English
• Publisher: Academic Press
• Release date: Jul 22, 2021
• ISBN: 9780128212677

Book preview

Trichinella and Trichinellosis

Edited by

Fabrizio Bruschi

Department of Translational Research, N.T.M.S., School of Medicine, Università di Pisa, Pisa, Italy

Table of Contents

Cover image

Title page

Copyright

Dedication

List of contributors

Foreword

Preface

Acknowledgments

Part I: General aspects

Chapter 1. History of the parasite and disease

Abstract

1.1 History of the discovery

1.2 Paleopathological findings

1.3 Conclusions

Acknowledgment

References

Chapter 2. The genetics of Trichinella populations: a study in contrasts

Abstract

2.1 Species of Trichinella harbor distinct levels of genetic variability, reflecting contrasting histories

2.2 Related species of Trichinella maintain distinctions despite occasional gene flow among them

2.3 Extreme inbreeding in Trichinella typically engenders highly uniform infections

2.4 Work remains to establish efficient, robust tools for outbreak tracing where populations are highly inbred

2.5 Population genetics sheds light on the origins of current challenges

References

Chapter 3. Taxonomy of the Trichinella genus

Abstract

3.1 Introduction

3.2 Expansion of the single species concept of Trichinella

3.3 The taxonomy of the genus Trichinella

3.4 Phylogeny of the Trichinella genus

3.5 Zoogeography of the Trichinella genus

3.6 The key for Trichinella taxon identification

3.7 The Trichinella biobank

3.8 The importance of Trichinella taxon identification

3.9 Concluding remarks and future prospective

References

Chapter 4. Biology of Trichinella

Abstract

4.1 Introduction

4.2 Overall structure

4.3 Life cycle

4.4 Muscle larvae

4.5 Adult worm

4.6 Newborn larvae of Trichinella

4.7 Body wall of Trichinella

4.8 Locomotion and movement

4.9 Protection

4.10 Exocrine system

4.11 Cyst (the parasite nurse cell complex or capsule)

References

Chapter 5. Proteomics of Trichinella

Abstract

5.1 Global proteomic analysis of Trichinella

5.2 Functional characterization of Trichinella proteins

References

Chapter 6. Epidemiology

Abstract

6.1 Introduction

6.2 Trichinella hosts

6.3 Trichinella cycles

6.4 Trichinella spp. and the international trade of live animals and meat

6.5 Trichinella infections in humans

6.6 Trichinella and trichinellosis in the world

6.7 Conclusions

References

Part II: Immunology and immunopathology

Chapter 7. Immunity to Trichinella

Abstract

7.1 Introduction

7.2 Primary and secondary infections: kinetics and resistance

7.3 Mechanisms of immunity to enteral stages of infection

7.4 Immunity to parenteral stages of infection

7.5 Mechanisms of immunity in nonrodent hosts

7.6 Conclusions

Acknowledgments

References

Chapter 8. Immunopathology of myositis, myocarditis, and central nervous system involvement in trichinellosis

Abstract

8.1 Introduction

8.2 Conclusions

References

Part III: The disease

Chapter 9. Trichinellosis in animals

Abstract

9.1 Introduction

9.2 Swine

9.3 Horse

9.4 Ruminants

9.5 Carnivores

9.6 Nonhuman primates

9.7 Birds

9.8 Reptiles

9.9 Conclusions

References

Chapter 10. Clinical picture and diagnosis of human trichinellosis

Abstract

10.1 Infectious doses, severity of the disease, and clinical forms

10.2 Description of the moderately severe form

10.3 Severe forms and complications

10.4 Other forms

10.5 Biological diagnosis

10.6 Circumstances of diagnosis

10.7 Conclusion

References

Part IV: Diagnosis and treatment

Chapter 11. Anatomical pathology

Abstract

11.1 Introduction

11.2 Skeletal muscle involvement

11.3 Electron microscopy data

11.4 More about the nurse cell

11.5 Myocardial involvement

11.6 Central nervous system involvement

11.7 Lung involvement

11.8 Renal involvement

11.9 Liver involvement

11.10 Small bowel involvement

11.11 Conclusion

References

Further reading

Chapter 12. Immunodiagnosis

Abstract

12.1 Introduction

12.2 Source of antigens

12.3 Immunodiagnostic assays

12.4 Evaluations and recommendations

12.5 Conclusions

12.6 Protocol for enzyme-linked-immunosorbent-assay

References

Chapter 13. Molecular methods for identifying and diagnosing Trichinella; from historical perspectives to the -omics revolution

Abstract

13.1 Introduction

13.2 Identifying Trichinella genotypes; prepolymerase chain reaction technologies

13.3 Polymerase chain reaction and identifying Trichinella genotypes

13.4 DNA sequencing

13.5 Transcriptomics, genomics, and Trichinella

13.6 The future

References

Chapter 14. Treatment

Abstract

14.1 Available antiparasitic drugs

14.2 Control of inflammation—role of glucocorticosteroids

14.3 Special recommendations

References

Part V: Control measures

Chapter 15. Preharvest and postharvest control of Trichinella in meat

Abstract

15.1 Introduction

15.2 Preharvest prevention of infection

15.3 Postharvest prevention

15.4 Postharvest processing

15.5 Trade

15.6 Summary

References

Chapter 16. Antigenic shift during Trichinella cycle, consequences for vaccine developments

Abstract

16.1 Introduction

16.2 Evaluation of anti-Trichinella vaccine candidates: toward a proof of concept?

16.3 Vaccine developments: from irradiated parasites to antigen pools from Trichinella sp

16.4 Purification of protein with monoclonal antibodies and new vaccination approaches

16.5 From wet lab to dry lab to select candidate vaccines

16.6 Caveats and future developments of anti-Trichinella vaccines

16.7 Future developments for a vaccine against Trichinella, a foodborne zoonotic parasite

Acknowledgments

References

Index

Copyright

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Dedication

A Linda, Francesco, Carlotta, and Giovanni

List of contributors

Alexandra Bastian

University of Medicine and Pharmacy Carol Davila, Bucharest, Romania

Colentina Clinical Hospital, Bucharest, Romania

Ewa Bilska-Zajac,     National Veterinary Research Institute, Pulawy, Poland

Pascal Boireau,     INRAE, ANSES, ENVA, UMR BIPAR, Laboratory for Animal Health, Maisons-Alfort, France

Fabrizio Bruschi,     Department of Translational Research, N.T.M.S., School of Medicine, University of Pisa, Pisa, Italy

Laura Campbell,     Lydia Becker Institute of Immunology and Inflammation, Wellcome Trust Centre for Cell Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom

Carmen-Michaela Cretu

University of Medicine and Pharmacy Carol Davila, Bucharest, Romania

Colentina Teaching Hospital, Parasitology Department, Bucharest, Romania

Jean Dupouy-Camet,     Paris University Medical Faculty, Paris, France

Fernando A. Fariña

Faculty of Veterinary Sciences, Parasitology and Parasitic Diseases, University of Buenos Aires, Buenos Aires, Argentina

National Scientific and Technical Research Council (CONICET), University of Buenos Aires (UBA), Animal Production Research Institute (INPA), Buenos Aires, Argentina

Raffaele Gaeta,     Division of Paleopathology, Department of Translational Research, University of Pisa, Pisa, Italy

H. Ray Gamble,     National Academy of Sciences, Washington, DC, United States

Richard K. Grencis,     Lydia Becker Institute of Immunology and Inflammation, Wellcome Trust Centre for Cell Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom

Grégory Karajian,     INRAE, ANSES, ENVA, UMR BIPAR, Laboratory for Animal Health, Maisons-Alfort, France

Sukhonthip Khueangchiangkhwang,     Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan

Mingyuan Liu,     Jilin University, Changchun, P.R. China

Alessandra Ludovisi,     Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy

Mabel Ribicich

Faculty of Veterinary Sciences, Parasitology and Parasitic Diseases, University of Buenos Aires, Buenos Aires, Argentina

National Scientific and Technical Research Council (CONICET), University of Buenos Aires (UBA), Animal Production Research Institute (INPA), Buenos Aires, Argentina

Yoichi Maekawa

Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan

Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan

Emilia Manole

Colentina Clinical Hospital, Bucharest, Romania

Victor Babeş National Institute of Pathology, Bucharest, Romania

María Ángeles Gómez Morales,     Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy

Isao Nagano,     Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan

Mariana I. Pasqualetti

Faculty of Veterinary Sciences, Parasitology and Parasitic Diseases, University of Buenos Aires, Buenos Aires, Argentina

National Scientific and Technical Research Council (CONICET), University of Buenos Aires (UBA), Animal Production Research Institute (INPA), Buenos Aires, Argentina

Edoardo Pozio,     Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy

Alice Raffetin,     Department of Infectious and Tropical Diseases, SMIT, CHIV, Villeneuve-Saint-Georges, France

Veronica Rodriguez-Fernandez

Department of Translational Research, N.T.M.S., School of Medicine, University of Pisa, Pisa, Italy

PhD School of Infectious Diseases, Microbiology and Public Health, Sapienza University of Rome, Rome, Italy

Elena Cecilia Rosca,     Department of Neurology, Victor Babes University of Medicine and Pharmacy, Timisoara, Romania

Benjamin M. Rosenthal,     United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, United States

Yuzo Takahashi,     Department of Parasitology, Graduate School of Medicine, Gifu University, Gifu, Japan

Peter C. Thompson,     United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, United States

Isabelle Vallée,     INRAE, ANSES, ENVA, UMR BIPAR, Laboratory for Animal Health, Maisons-Alfort, France

Xuelin Wang,     Jilin University, Changchun, P.R. China

Zhiliang Wu

Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan

Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan

Hélène Yera

Paris University Medical Faculty, Paris, France

Reference Laboratory for Surveillance of Human Trichinellosis, Department of Parasitology-Mycology, Cochin Hospital, Assistance Publique Hôpitaux de Paris, Paris, France

Dante S. Zarlenga,     Agricultural Research Service, Animal Parasitic Diseases Laboratory, Beltsville, MD, United States

Foreword

Diseases caused by parasitic worms (helminths) are of incalculable importance in human and veterinary medicine. Few helminth species, however, have received the attention that has been lavished so assiduously on the nematode Trichinella spiralis. Comprehensive reviews of T. spiralis and other members of the genus Trichinella have been written from time to time, but knowledge of the parasite and its attributes have expanded so enormously in recent years that a new survey has been sorely needed. This book, edited by Prof. Bruschi, deserves an enthusiastic welcome.

Prof. Bruschi has been an authoritative figure in parasitology for many years. His eminence in research and teaching is globally recognized, and he is particularly renowned in the area of Trichinella and trichinellosis. The long arc of his career has enabled him to garner review chapters from scientists with special expertise in the various aspects of the subject. The result has been not only the summarization of an extraordinary amount of information but also the presentation of science that is grounded in the most recent advances in modern biology.

Trichinella came to our awareness at a time when the concepts of miasma and spontaneous generation were in the air but were soon to be overthrown. This tiny worm, barely visible without a microscope, demanded our attention by subjecting humans to outbreaks of lethal and excruciatingly painful illness. The role of domestic pigs in propagating the disease was at once apparent, and the disease took on a special significance as a zoonosis. As such, its relevance extended far beyond the world of academia, reaching also into the realms of industry, agriculture, economics, and even, on occasion, international diplomacy.

After almost two centuries, trichinellosis remains a major concern of biomedical research, livestock management, and public health policy. Collaboration in these areas has strengthened the bonds between human and veterinary medicine and thereby played a part in the emergence of a more integrated view of one health.

A major impetus to much of the biological research on Trichinella was its recognition as a human pathogen that could be easily, safely, and economically manipulated in research laboratories. The parasite became hugely popular as a subject of experimentation. In modern times the genus Trichinella has continued to be employed in innumerable investigations on basic and applied biological topics—as is so brilliantly and usefully recounted in the pages that follow.

William C. Campbell, FRS PhD

Drew University, retired.

Preface

Fabrizio Bruschi, M.D.

Forty years ago, in 1980, I met for the first time the parasitic nematode Trichinella spiralis in the laboratory of Rubén Binaghi at I.N.S.E.R.M. UNIT 104 of the Saint Antoine Hospital in Paris, France.

I remained fascinated by this parasite and since then most of my research activity has been devoted to the study of the host–Trichinella relationship in experimental models as well as in humans.

Although the impact of trichinellosis on global health is low, compared to other intestinal helminthiases such as ascariasis, hookworm, and trichuriasis, the study of Trichinella remains useful to understand the fine mechanisms of the host–parasite relationship at intestinal level.

Why not consider the incredible changes induced by the parasite in the skeletal muscle cell which undergoes fine modifications essential for the survival and growth of the parasite. The study of these changes could give an important contribution to the comprehension of the pathogenesis of primary myopathies.

Despommier in 1996 stated: "Therefore, despite the facts that the Hubbel space telescope now functions properly, the human genome project is more than half finished, and the majority of households in Plum Tree, England, have a television set and a microwave oven, there still is and always will be an urgent need to recognize disease caused by Trichinella spp. and to treat those who are acutely ill from it."

Are we still there?

The aim of this book, following the awesome book published in 1983 by Prof. W.C. Campbell, is to update the state of the art of this topic: where are we in the roadmap to control trichinellosis, and what is the progress of the knowledge.

I hope this book will be able to answer these questions.

It is a long way from paleopathological findings in the mummies to more advanced technology of diagnosis and control measures.

Students, biologists, physicians, and scientists involved in the study of the parasite and disease, particularly those willing to start the research on this fascinating field, will, I hope, benefit from this book.

Finally, I am very grateful to Jean Dupouy-Camet, Edoardo Pozio, Raffaele Gaeta, Dante Zarlenga, Maria Angeles Gomez-Morales, Wieslaw Kozeck, Frits Franssen, H. Ray Gamble, Karsten Nockler, and Benjamin M. Rosenthal for critically reading some chapters, giving useful advice to the authors.

In particular I want to thank Mona Zahir for editorial assistance.

Acknowledgments

I am grateful to Rubén A. Binaghi, Dickson. D. Despommier, Derek Wakelin, William. C. Campbell, Darwin K. Murrell, Zbigniew S. Pawlowski, Joost Ruitenberg, Frans van Knapen, and Judith A. Appleton for inspiring me with their publications.

Part I

General aspects

Outline

Chapter 1 History of the parasite and disease

Chapter 2 The genetics of Trichinella populations: a study in contrasts

Chapter 3 Taxonomy of the Trichinella genus

Chapter 4 Biology of Trichinella

Chapter 5 Proteomics of Trichinella

Chapter 6 Epidemiology

Chapter 1

History of the parasite and disease

Raffaele Gaeta¹ and Fabrizio Bruschi²,    ¹Division of Paleopathology, Department of Translational Research, University of Pisa, Pisa, Italy,    ²Department of Translational Research, N.T.M.S., School of Medicine, University of Pisa, Pisa, Italy

Abstract

Trichinella has been a companion of humanity for thousands of years, so that some religious taboos on the consumption of pork probably derive from the risk of getting sick that is associated with its ingestion. However, man has only managed to give a face and a name to the pathogen in modern times when, thanks to the intuition of great scientists and their pioneering experiments, it was possible to understand the pathogenic mechanisms of the parasite. Their observations and discussions, sometimes very vibrant, have led to the adoption by the authorities of stricter rules on food quality control which have helped to drastically reduce the outbreaks of trichinellosis raging in Europe and the United States. In this chapter we describe the troubled history of the discovery of the parasite (certainly comparable to a 19th century romance novel) and illustrate the major contributions that great scientists have made to the understanding of the pathogen. Furthermore, the presence of Trichinella in antiquity has not only been hypothesized in theory, but has been concretely identified by analysis of paleopathology, which is the science that studies ancient human remains. Lastly, therefore, we illustrate the five mummies infected by the parasite, as described in literature.

Keywords

History; Trichina; paleopathology; mummies; Paget; Owen

The pig […] is unclean for you. Their flesh you shall not eat, and their dead bodies you shall not touch; they are unclean for you (Leviticus 11:7–8).

The New American Bible (2002)

[…] the pig, which indeed has hoofs and is cloven-footed, but does not chew the cud and is therefore unclean for you. Their flesh you shall not eat, and their dead bodies you shall not touch (Deuteronomy 14:8).

The New American Bible (2002)

Prohibited to you are dead animals, blood, the flesh of swine […] (Qur’an 5:3).

Sahih International (1997)

Among the practices imposed by both Judaism and Islam, the prohibition to consume pork products is certainly among the most respected. This tradition is based on solid health and hygiene convictions since there are dozens of diseases carried by pigs; among them, trichinellosis definitely represents a significant part. Man has always had to share his existence with that of the parasite, in fact, traces of Trichinella have been found in ancient human remains dating back to about 3500 years ago. However, before illustrating the paleopathological findings, it is necessary to narrate the story of the discovery of the parasite and the route to the full understanding of its biological cycle and the risks associated with its presence in the host. The story begins at the threshold of the 19th century and involves great and visionary scientists.

1.1 History of the discovery

1.1.1 Cysts with bony point. First observations (1822–33)

The first scientific description of the presence of Trichinella is dated 1835, but a retrospective overview allows one to identify previous pioneering observations of the alterations caused by the parasite, but without the understanding of the etiology. These papers are chronologically placed in the first half of the 1800s, a time of great positivist impulse.

In 1822 the physician Friedrich Tiedemann (1781–1861) described white stony concretions in the muscles of a human cadaver, but he never suspected their parasitic origin, because he did not even observe the specimens under a microscope. In fact, the specimen was only chemically analyzed by Gmelin, and a short note published in Froriep’s Notizen reported that Tiedemann found at the autopsy on a man, […], in most of the muscles, especially in the extremities, white, stony concrements. They lay between the fiber bundles in the cellular tissue; frequently also on the walls of the arteries, were 2 to 4 lines long and rounded. The chemical examination, done by Gmelin, showed 75 parts phosphate of lime, 7 parts carbonate of lime, and 20 parts of animal material like egg white or fibrin (Blumer, 1939).

We will never be sure that those concretions were caused by the parasite, but considering the differential diagnosis, the most likely cause are probably encapsulated and calcified Trichinella larvae (Campbell, 1983).

In 1828 Mr. Peacock, during an autopsy performed at Guy’s Hospital in London, identified some speckling of the muscles adjacent to the larynx. He did not write any scientific article, but made a dry preparation for educational purposes, which was mentioned in the Hodgkin’s Catalogue of the Museum as sterno-hyoideus muscle speckled with numerous minute bony points. Peacock did not recognize the parasitic origin, but in 1858 a retrospective analysis of the same samples performed with the microscope showed that those described were worm larvae.

John Hilton (1804–78), Demonstrator of Anatomy at Guy’s Hospital, observed specks in some pectoral and respiratory muscles during an anatomical dissection in 1833. In detail, he observed that in-between the fibers there were several oval bodies, transparent in the middle and opaque at either end, about 1/25 of an inch in length (Blumer, 1939). His contribution was innovative since he examined the specimen with a microscope without however identifying any internal structure. He was the first to hypothesize their parasitic origin, even if he wrongly believed them to be the larvae of cestodes (Cysticercus); in fact, he reported his findings in an article in the London Medical Gazette entitled Notes on a Peculiar Appearance Observed in Human Muscle, Probably Depending Upon the Formation of Very Small Cysticerci (Hilton, 1833). He even tried, for the first time, to infect his rabbits by subcutaneous inoculation of the material he had analyzed, but his attempt turned out to be unsuccessful (Blancou, 2001).

1.1.2 Paget, Owen, and the first description (1835)

Officially, the first article in which the new nematode was named and scientifically described was published in 1835 by Richard Owen (1804–92) (Owen, 1835). However, the story of the discovery is troubled and it is certainly comparable to a 19th century romance novel.

Doubts about the real attribution of the discovery date back to 1866 when on the pages of The Lancet, an English helminthologist, Thomas Spencer Cobbold (1828–86) began to discredit Owen (Cobbold, 1866a,b). In fact, we actually know that the honor of discovery must surely be given not to Owen, but to a brilliant 21-year-old medical student of London, James Paget (1814–99) (Fig. 1.1).

Figure 1.1 Portraits of Sir Richard Owen (left) and Sir James Paget (right). CC BY 4.0.

We are facing, both Owen and Paget, two giants of science who have left their indelible mark on the history of biology and medicine. Richard Owen is a controversial figure; his interests ranged from biology, comparative biology to paleontology (he is remembered today for coining the word Dinosaur). Moreover, Owen was the first president of the Microscopical Society of London in 1839 and edited its journal, The Microscopic Journal, at a time when microscopic observations were pioneering. However, he is notorious for being a strong opponent of Charles Darwin and his theory of the evolution of the species and for repeatedly trying to attribute to himself some of the discoveries made by other scientists.

Sir James Paget is considered one of the founders of modern scientific medical pathology. He has literally linked his name to several medical discoveries, since we can list the Paget’s disease of bone (i.e., a disease involving cellular remodeling and deformity of bones), Paget’s disease of the nipple (i.e., a breast cancer spreading into the skin around the nipple), extramammary Paget’s disease (i.e., a form of primary or secondary intraepithelial carcinoma in genitalia), Paget–Schroetter disease (i.e., a form of upper extremity deep vein thrombosis) and Paget’s abscess (i.e., an abscess recurrence at the same site after apparent cure).

On February 2, 1835, James Paget, at the time a 21-year-old student in practice at St. Bartholomew’s Hospital in London, started the autopsy of a cadaver of a 40-year-old Italian (Paulo Bianchi), deceased of tuberculosis. During the dissection he described an immense number of minute whitish specks that proved to contain a peculiar animalcule (Neghina et al., 2012). The hospital did not even possess a dissecting lens, so he asked the help of Robert Brown, the Keeper of Botany who was among the first to observe cell nuclei and discovered Brownian movement, who owned a simple microscope. Paget carefully sketched the worm on the papers (now preserved in the library of the Royal College of Surgeons of England) and presented his discovery on February 6, 1835, to the Abernethian Society, a medical student club of his hospital. However, Paget, surprisingly, never published any scientific article about his discovery. He was a young student, and from his words it is possible to understand his doubts derived from inexperience. He wrote: I do not know whether I shall write the description myself, or whether Mr. Owen, our lecturer on Comparative Anatomy will do it—I should rather think the latter, as having used far more powerful microscopes than I had, he has been able to make out their organization more clearly. Whichever be the case, I have taken care that I should receive at least some credit for the discovery (Campbell, 1979). Shortly afterwards a specimen of infected muscle was sent to Richard Owen, who understood the nematoid nature of the worm, and named it Trichina spiralis, due to the shape of the coiled nematode. Paget described that, under the low power microscope, the specks were elliptical cysts with attenuated extremities more opaque than the body of the cyst, which was translucent enough to show that it contained a minute coiled-up worm (Blumer, 1939). The worms were about 1/50 of an inch in length, and 1/100 of an inch in width. Moreover, he affirmed that the cysts were generally in single rows parallel to the muscle fibers and that they were composed of condensed and compacted lamellae of cellular tissue (Blumer, 1939). Then, he removed some worms from the cysts and discovered that they were generally in two to three spiral coils that were 1/25 to 1/30 of an inch in length, and from 1/700 to 1/800 of an inch in diameter (Blumer, 1939). In a very ungrateful way, Owen gave Paget only minimal credit for the discovery and earned the applause of his professional brethren.

According to Campbell (1979), we can hypothesize several reasons for Paget not publishing the description of the new worm: (1) the inexperience and the fear of making mistakes in phylogenetic assignation; (2) the absence of a microscope with good resolution and lack of knowledge in the microscopic field; (3) being a young doctor with no reputation, thus risking not being able to publish the paper on a prestigious journal; (4) the absence of previously published articles, which would have led to the skepticism of the scientific community; and (5) no political support in his relationships in the hospital.

However, in Paget’s numerous writings at a mature age, there is never any regret or resentment toward his teacher. In fact, in a letter to The Lancet published in 1866, Paget recalls his discovery: An abstract of my communication is in the second volume of the Abernethian Society’s Transactions. It contains a description of the entozoon-not indeed complete, but I believe not inaccurate…. I proposed immediately afterwards…to send a description of it to the Medical Gazette, but from this I was dissuaded; and the admirable memoir of Professor Owen, much more complete and exact in zoological detail than anything I could have written, was communicated to the Zoological Society on Feb. 24th (Paget, 1866).

Paget wrote, about Owen’s paper: It mattered little; the repute of the discovery would have been of no use to me; and I should have gained less happiness by disputing for it and obtaining it than I have enjoyed in the personal friendship with Owen ever since (Campbell, 1979).

The original specimen of the infected muscle was deposited in St. Bartholomew’s Hospital museum, but unfortunately it seems that a German bomb in 1940 destroyed part of the building and the specimen with it (Despommier and Campbell, 2013).

1.1.3 The discovery of the nematode life cycle (1835–60)

The article published by Owen in 1835 had a strong impact on the scientific community. Since then, there have been numerous descriptions of the so-called Trichina and, within a few years, great strides had been made in understanding the life cycle of the parasite.

Henry Wood, a practitioner in Bristol, England, in 1835 wrote that in October of the previous year, during the dissection of a corpse of a 24-year-old man who died of pericarditis, he observed minute whitish specks. He also said he wanted to publish his notes, but was discouraged to do so. He was certainly the first scientist to relate the presence of the parasite to a pathology of man, which he called acute rheumatism (Cook, 2001).

In the same year Arthur Farre (1811–87) in London, described the food channel of the parasite and the presence of tiny aggregate structures that are now known as Farre's granules (Farre, 1835).

Joseph Leidy (1823–91) from Philadelphia, was a great scientist with many interests. Nowadays he is best known for his paleontological discoveries as he was the first to discover and describe dinosaur remains in the United States. However, he is also unanimously considered the founder of parasitology in America. In 1846, while eating a slice of pork, he noticed the presence of tiny specks that reminded him of a specimen observed during an autopsy shortly before. Analyzing the flesh under the microscope he found a massive presence of the parasite (Leidy, 1846). This discovery, which may only seem like a curious anecdote, represented actually a tremendous progress towards the prevention of the disease since Leidy revealed the mode of transmission of the Trichina to humans.

In Göttingen, Germany, in 1850 Ernst Herbst (1803–93) tried to test the parasite’s transmission from infected flesh with an experiment. He infected a badger with contaminated dog meat and then used its meat to feed three puppies. Subsequently, analyzing their meat under a microscope, he found numerous larval cysts in the muscles of all three (Herbst, 1851). However, as Campbell stated, Herbst’s report of 1851 should thus have been seminal, but was largely ignored (1983).

In the same years, another step toward a complete understanding of the Trichinella’s life cycle took place. Two scientists, Felix Dujardin (1801–60) from France and Carl von Siebold (1804–85) from Germany, understood that the previously observed worm was an immature form, and suggested that it was a progeny of a nematode previously described in its adult form (Reinhard, 1958). Similar considerations were formulated in 1855 in Germany by Friedrich Küchenmeister (1821–90) who had successfully described the life cycle of the Cysticercus in the same period. Thanks to his knowledge in the microscopic field, he recognized similarities between Trichinella and Trichuris, but believed that they belonged to the same family of parasites.

A more precise and complex microscopic description of the worm was formulated by Rudolf Leuckart (1822–98), a great zoologist of Giessen, Germany. In 1857, he fed mice with infected flesh, and 3 days later he had found that the ingested worms came out of their cysts into the gut of the mice. The fact that impressed him was that they appeared much bigger than they had been when encysted in the muscle of their former host. Based on these observations, he wrote that the males are only half as large as the female, hardly longer than 1.5 mm, with four nodular papillae between the conical terminal processes. The dorsum is elongated, as in the female which grows to be 3 mm or longer and also exceeds the male in thickness. In worms of corresponding development, the chylus intestine of the female is much longer than is that of the male, so that the cell bodies, on the contrary, are relatively less developed. The shell-free eggs develop … into tiny embryos … that fill the uterus of the impregnated female and are born in great numbers. … These embryos burst through the intestinal wall of their host to wander out into the musculature and to develop in a few weeks into larvae … which, under the shelter of a usually calcified structureless capsule, live for years, while the sexually mature worms die … after about five weeks (Blumer, 1939). However, Leuckart perpetuated Küchenmeister’s mistake, stating that the Trichinella and Trichuris were the same worm observed in two moments of their life cycle. He wrote a letter to the Paris Academy of Sciences that inserted his statement in the printed record issued in September 1859.

At this point, a true giant of science, considered the father of modern pathological anatomy, entered the scene: Rudolf Ludwig Karl Virchow (1821–1902) from Berlin (Fig. 1.2). Besides dealing with various topics (he was an anthropologist, pathologist, prehistorian, writer, editor, and politician), after the middle of the 19th century he worked in the field of parasitology. The beginning of his work on understanding the nature of the Trichinella dates back to July 1859, when he performed the autopsy of an individual infected with worm larvae. He used some of the infected muscles to feed an old dog that died a few days later. Analyzing the animal’s intestine, the German scientist identified dozens of nematodes that he described as adult Trichinella worms, thus rejecting Küchenmeister and Leuckart’s hypothesis that Trichinella and Trichuris were the same types of worm. Trichinella was therefore clearly a new species. Understanding the importance of his observation, Virchow decided to write to the Paris Academy of Sciences as Leuckart did, and his paper on the maturation of Trichinella was finally published in November 1859 (Virchow, 1859). It was evidently a great month for the history of science since on November 22, 1859 Charles Darwin published the fundamental text On the Origin of Species, which had a significant impact on the scientific community. Thanks to his observations, Virchow was among the first to propose the use of the microscopic test (known as trichinoscopy) to assess the health of pork slaughtered in Germany. Evidently, his suggestions were not well received by German butchers, so much so that he claimed: it’s a crime to accuse us of an exaggerated fear, a trichinophobia (Dupouy-Camet, 2015a). Furthermore, he also had to clash with the Prussian Chancellor Otto Von Bismarck with whom he had had some disagreements for political reasons in the past. The contrast between politics and health shows that history is repetitive: the strong debate between US President Donald J. Trump and Anthony Fauci, virologist and lead member of the White House Coronavirus Task Force, on the rules to be adopted to face the COVID-19 pandemic in the United States is topical at time of writing. Virchow was putting pressure on the government to enforce rules for an improvement in the hygienic conditions of slaughterhouses. Thus the legend of the so-called sausage duel between the two challengers was born. According to the tradition, in 1865 Bismarck became so tormented by Virchow’s insistence that he challenged him to a duel. As the person who had been challenged, Virchow had the right to determine what weapons would be used. He proposed that they each consume a pork sausage: one prepared with parasitized meat and a healthy one. Fearing more parasites than usual weapons, Bismarck flatly apologized (Dupouy-Camet, 2015a). Therefore in 1866 the Germanic provinces were among the first countries to adopt a series of laws requiring strict control of reared pigs and later, in 1879, Prussia introduced the routine use of trichinoscope (Brantz, 2008).

Figure 1.2 Portrait of Virchow. Public domain.

At this point, it became increasingly clear how the life cycle of the Trichinella developed and how much it could infect men, but it had not yet been understood that the worm could cause the death of a person in a short time. The first autopsy on which trichinellosis was officially declared as the cause of death dates back to 1860 and was performed by Friedrich Albert von Zenker (1825–98) in Dresden, Germany (Fig. 1.3). The body belonged to a 20-year-old servant girl who, shortly before she died, showed the same symptoms of typhoid fever, that is, high fever, exhaustion, and above all muscular pains in her arms and legs so strong that she could not sleep. She then developed joint contractures followed by generalized edema and apathy which led her to death after 33 days of agony. The microscopic observation allowed Zenker to describe dozens of intramuscular parasites and worms in the intestines, which suggested to the scientist that the Trichinella was spending its entire life cycle in the same host. He sent muscular samples to Leuckart and Virchow that successfully infected a rabbit, a dog, and a pig. As a real detective, Zenker investigated the working environment of the girl (a tavern) and, after he interviewed the landlord, he discovered that the pork consumed shortly before the onset of the symptoms was heavily infected with the parasite so that all the people who consumed the same food got sick. According to the legend, the scientist ended his conversation with the words Accordingly we have then the first diagnosis of trichinosis during life (Blumer, 1939). Zenker, therefore, had a clear picture of the transmission of the parasite and assumed that the Trichinella would spread through the host’s body via chyle ducts or bloodstream. These observations, entitled Ueber die Trichinenkrankheit des Menschen and published in 1860 (Zenker, 1860), were one of the fundamental moments in the history of parasitology.

Figure 1.3 Portrait of Friedrich Albert von Zenker at mature age. Public domain.

1.1.4 Trichinella as a pathogen: from scientific curiosity to health problem (1860–1900)

It was clear at this point how dangerous the Trichinella was, in fact from 1860 to 1877, approximately 150 epidemics were registered in Europe, including about 3800 cases and 281 deaths (Neghina et al., 2012). Germany was the most affected country since between 1860 and 1880, there were 513 deaths out of 8491 cases, giving a mortality rate of 6% (Lehmensick, 1970). Later, from 1881 to 1898, 3822 cases occurred in Prussia (225 deaths) and 1634 (76 deaths) in Saxony (Braun, 1908), although certainly many deaths from trichinellosis were not diagnosed, as proved by autoptic experience. The first outbreak of Trichinella identified and described in France was in Crépy-en-Valois, France in 1879 (Laboulbène, 1881), after which many others were described (Fig. 1.4).

Figure 1.4 A commemorative plate with printed decorations from the Choisy-le-Roi faience factory is captioned: L’année 1866, la trichinose. It shows a Norman peasant kneeling in front of his pigs and praying to the sky: Oh bon Saint Antoine, préserve nous de cette horrible maladie [Oh, good Saint Anthony, save us from this horrible disease]. Courtesy Prof. J. Dupouy-Camet (private collection).

Then, in 1881, Malzac and Boissier, inspired by the projectors used by Pasteur on silkworm eggs, proposed a large-scale meat inspection test (Neghina et al., 2012). As a result, at the end of the century, trichinoscopy (Fig. 1.5) was commonly used on pork specimens throughout Europe, especially in Eastern countries and Germany, while it was not applied in the United States. At the time the United States was a major exporter of meat to Europe, and in fact, the lack of healthy controls is associated with the 1880–89 Trichinella outbreak in Europe. The consequence was a real diplomatic and economic crisis between the two sides of the Atlantic Ocean as the major European countries refused to import American pork for several years (the so-called German–American pork war) (Hoy and Nugent, 1989). As reported by Campbell (1983) Partial or total embargoes were imposed in 1879 by Italy, Portugal, and Greece; in 1880 by Spain and Germany (chopped pork only); in 1881 by France, Austria-Hungary, Turkey, and Romania; in 1883 by Germany (all pork products); and in 1888 by Denmark. Actually, the countries of the Old Continents used the excuse of the spread of the parasite as a pretext. The United States was becoming a major economic power with the risk of becoming the strongest country in the world, so Europe tried to weaken it by boycotting an economic sector, the export of meat, which was very prosperous at the time.

Figure 1.5 Trichinoscopy in Germany. Butchers bring their pork meat to the inspector’s office. From a newspaper of 1881. Courtesy Prof. J. Dupouy-Camet.

Trichinella was now such a popular topic that publications multiplied every year; in 1883 the fundamental monograph "La trichine et la trichinose" by Johanès Chatin (1847–1912) was published in France (Chatin, 1883). The parasite was no longer a microscopic and elusive organism, since with the improvement in photographic techniques, William Radam (1844–1902), a German immigrant to the United States, published for the first time, in 1890, two photographs of larvae (Radam, 1890). Until then, in fact, the articles were only supported by manual drawings that were also considered more incisive (Campbell, 2001).

In the medical field, a discovery can be defined as fundamental when it has a significant impact on living patients, both in the prevention and early diagnosis. The first major contribution to the diagnosis came in 1862 when Nikolaus Friedreich (1825–82) of the University of Heidelberg, Germany, diagnosed the presence of worm larvae in a small piece of biceps muscle from a patient, making it clear to the scientific community that biopsy on human specimens was a safe and effective method (Friedreich, 1862). Then, in 1897 Thomas R. Brown, a medical student at Johns Hopkins University, observed that all trichinellosis patients had a significant increase in eosinophils in their blood (i.e., eosinophilia) (Brown, 1897). We currently know that eosinophils are cells of the immune system that respond, along with the increase in total IgE, to the presence of parasites (Bruschi et al., 2008), so Brown’s observation became a major contribution to the diagnosis of trichinellosis. Lastly, in 1899 Kabitz designed the first projectional trichinelloscope by the company Zeiss from Jena, Germany (Neghina et al., 2012).

The great doctor, botanist, and naturalist Carl von Linné (1707–78) once wrote "Nomina si nescis, perit et cognitio rerum" (i.e., if you don’t know the name, the knowledge of things dies too), so we want to conclude with a semantic note. In 1895 a French helminthologist, Louis-Joseph Alcide Railliet (1852–1930), renamed the parasite as Trichinella spiralis since he noticed that the original name, Trichina spiralis, proposed by Owen in 1835 had been attributed 5 years earlier to a genus of Diptera, an insect (Railliet, 1895).

All these great scientists have contributed, step by step, to the complete understanding of the parasite, from its microscopic structure to its life cycle. The worm, initially considered an innocuous intruder, was then identified for what it is, a dangerous parasite capable of causing severe and potentially fatal disease. Thanks to their discoveries, food controls were intensified with special laws that drastically limited the Trichinella outbreaks that raged in Europe in the past.

1.2 Paleopathological findings

Paleopathology is the science that studies ancient human remains, both osseous and mummified. This discipline combines multiple scientific fields and uses the most modern techniques. It adopts medical procedures that vary from imaging (MRI, CT) (Izzetti et al., 2020), to classical pathological anatomy (Gaeta et al., 2013), but with crossover to molecular biology (e.g., ancient DNA) (Patterson Ross et al., 2018), botany, and palynology (Ciuffarella, 1998). The contribution of parasitology dates back to the dawn of paleopathology itself, as we can identify the birth of paleoparasitology in 1910 when Ruffer described the discovery of Schistosoma eggs in an ancient Egyptian mummy (Ruffer, 1910).

Only a few studies have reported the observation of Trichinella in ancient human remains. The scarcity of the findings may be due to the taphonomic processes of mummification that cause the decay of the larvae, generally located in muscular cysts surrounded by a collagen capsule (Dupouy-Camet, 2015b). In the literature, there are only five known cases coming from different continents and different epochs (see Table 1.1).

Table 1.1

There is an equal involvement of both sexes, a spread over several continents, and a wide range of age (18 months to 42 years) and chronological dating (12th century BCE to CE 19th century).

1.2.1 Egypt (Deir-El-Bahari)

The first diagnosis of suspected trichinellosis in paleopathology was formulated in 1974 (De Boni et al., 1977). The mummy, dated to around 1200 BCE, belonged to Nakht, the weaver of pharaoh Setnakht (12th Dynasty), and was found in Deir-el-Bahari, near the modern Luxor, in 1904–05 during the excavation of the funerary temple of Menthuhotep II (11th Dynasty, c. 2010 BCE). The Egypt Exploration Fund’s expedition C.T. Currelly, founder of the Royal Ontario Museum (ROM) in Detroit, United States, participated. He bought the body and took it to the museum where it still is preserved today, hence the archival code ROM I. The use of histology and electronic microscopy allowed the identification of a possible parasitic cyst of Trichinella spiralis near the subcutaneous border of the intercostal muscle, as well as calcified eggs of Schistosoma spp. and Taenia spp., and macroremains of adult liver fluke (Fasciola hepatica) (Horne and Lewin, 1977; Reyman et al., 1977). Nakht was a royal weaver, so his work within a funerary temple may have given him access to more meat than the average member of the working-class Egyptian, but it was contaminated by several parasites (De Boni et al., 1977). Although the identification of the parasite is not without doubt, the article is deeply flawed due to the limited techniques of the time. Trichinella, which has a worldwide distribution, certainly existed in ancient Egypt as it still exists in the modern country (Youssef and Uga, 2014). This discovery confirms that the consumption of pork, for those who could afford it, was not forbidden in ancient Egypt. A previous study by Bruschi et al. (2006) revealed the presence of cysticercosis in a mummy of the Ptolemaic period, demonstrating that, in Hellenistic Egypt, the farming of swine, along with man an intermediate host of this parasite, was present and diffuse, as shown by some pictures and archaeological findings from late Egyptian civilization (Hecker, 1982).

1.2.2 Alaska, United States (Utqiagvik)

A few years later, in July 1982 in the village of Utqiagvik (modern Barrow, northern of Alaska) two mummies and three skeletons were found in a crushed house (Zimmerman and Aufderheide, 1984; Zimmerman, 1985). The bodies date back to CE 1510±70 years (radiocarbon dating) and probably belonged to the same family unit. One of the two mummies (called Southern body) was attributed to a 42-year-old woman who probably died of crushing chest injuries. In fact, the body was found near the exit from the house, with the roof collapsed that fractured her ribs. A complete autopsy showed that her lungs were atelectatic, with bilateral pleural effusions and about 300 cc of serosanguinous fluid. Subsequent histological investigations revealed numerous pathological conditions including focal calcification of the mitral valve, healed renal acute tubular necrosis, chronic cystic cervicitis, and osteoporosis. The lungs showed severe distress as they presented marked anthracosis, bronchiectasis, bilateral pleural adhesions, and fibrous apical cap; healed granulomas in her lungs and lymph nodes were probably caused by histoplasmosis. Finally, the diaphragm contained several small cystic structures suggestive of Trichinella larvae, currently thought to cause infection in Arctic populations through the uncooked meat of the polar bear (Zimmerman, 1998).

1.2.3 Spain (Toledo County)

The first European case in a mummy was described in 1991 and was found in a mummified body of a young child from Toledo County, Spain (Gomez-Bellard and Abel-Cortes, 1991). During the exploration of the ossuary in a family mausoleum, five burials containing three skeletonized individuals and two mummies were found. One of them belonged to a young girl about 2 years old, whose coffin was dated 1896. The analysis of the sections obtained from the spontaneously mummified muscles of the forearm revealed: some particles with a parasitic morphology, with birefringent cuticula, which present a spiral configuration (Gomez-Bellard and Abel-Cortes, 1991). The lesions were not surrounded by an inflammatory infiltrate, but the pattern and the destruction of the muscular fibers were compatible with the diagnosis of infection by worms of Trichinella spiralis. This finding is not surprising since the Toledo region is rich in pig farms and cases of trichinellosis have been reported in recent times (García-Sánchez et al., 2009). Also, smoked ham was considered an excellent stimulator for the correct growth of teeth in infants (Gomez-Bellard and Abel-Cortes, 1991). However, this finding has not been confirmed by subsequent molecular investigations. In fact, a tissue sample from the mummy was tested with Polymerase Chain Reaction for Trichinella but the result was negative (Pozio E, personal communication, 2018).

1.2.4 Chile (Cerro El Plomo)

In 1954 a well-preserved mummy of a boy (8–9 years old) was found near the top of Cerro El Plomo, Santiago (Chile), at about 5420 m above sea level. The body, belonging to the Inca culture (CE 16th century), was probably a sacrificial victim, but the extreme climatic conditions of the place determined a process of natural mummification by freezing. The body, transported to the Museo Nacional de Historia Natural de Santiago, underwent extensive histological examinations in 2003. The microscopic examination of the right quadriceps muscle revealed the presence of cystic structures with capsules compatible with encapsulated Trichinella larvae, as demonstrated through indirect immunofluorescence with a human hyperimmune serum specific for the parasite. (Rodriguez et al., 2011). The diagnosis was subsequently confirmed by histochemical stain (Fig. 1.6) and transmission electron microscopy (Rodriguez et al., 2017). However, it is still difficult to explain the presence of this parasite in South America in pre-Columbian era since Incas were mainly vegetarians, with the occasional intake of meat of llama, alpaca, and guinea pig (Dupouy-Camet, 2015b).

Figure 1.6 Von Kossa’s stain shows, in red color, the deposits of collagen type I around the cyst of Trichinella. Optical microscope. Reproduced with permission of John Wiley and Sons from Rodriguez, H., Espinoza-Navarro, O., González, M., Castro, M., 2017. Ultrastructural preservation of tissues and their reaction to the infection with trichinella in the El Plomo mummy: muscle fiber ultrastructure and trichinosis/mummy of the Cerro El Plomo. Microsc. Res. Tech. 80 (8), 898–903.

1.2.5 Greenland (Pissisarfik)

Finally, the Thule Culture (Greenland) Inuit mummy series represents an exceptional Arctic population. There are 14 individuals, eight mummies from Qilakitsoq (15th century) and six mummies from Nuuk, at the Pissisarfik site (16th century) (Lynnerup, 2015). The latter, except for one female individual aged 17, are all natural mummies of children aged 9–18 months. A histological sample of a muscle from an 18-month-old child mummy revealed possible infection with Trichinella larvae, albeit not entirely convincing. If confirmed by future investigations, this finding would be very interesting since, if we consider that the time from ingestion to encystment is approximately 1 month, and the parasite cannot be transmitted through breastmilk, the child would have been fed with raw meat a few months after birth.

1.3 Conclusions

In the 21st century, the majority of emerging infectious diseases are zoonoses (like trichinellosis) that are infection naturally transmitted from animals to humans (Ledger and Mitchell, 2019). Paleopathological studies and investigations of ancient DNA (aDNA) have seen a strong upsurge in recent years thanks to improved technology. The history of parasites begins to be less obscure and has its roots since the appearance of the first hominids. In particular, it is thought that there has been a marked increase since the Neolithic era, as the risk of zoonoses grows with the domestication of animals and thus the breeding and formation of stable urban agglomerates (Reinhard et al., 2013; Wolfe et al., 2007). The risks then increase due to several factors, including increased time since domestication (Morand et al., 2014), human migration, diet, urbanization, and population expansion (Ledger and Mitchell, 2019). Paleogenetic studies are therefore fundamental to understand the phylogeny of parasites, their evolution, the mechanisms of adaptation to hosts, and, above all, to understand how pathogens are evolving.

Therefore humans have always had to live with parasites, and the Trichinella, in particular, has marked some important moments in history. We can even hypothesize that the presence of the parasite could have changed in some moments the course of history. The suggestion that the discovery of the parasite caused on the population of the time was enormous and rapid, so that

Fyodor Dostoevsky in 1866, in his masterpiece Crime and Punishment, wrote: "[…] the whole world was condemned to a terrible new strange plague that had come to Europe from the depths of Asia. All were to be destroyed except a very few elect ones. There appeared some new sorts of trichinae, microscopic creatures, which were infesting the bodies of men. But these creatures were spirits endowed with intelligence and will. Men attacked by them immediately started raving and wen" (Dostoevsky, 2014).

The parasite has therefore perhaps influenced the course of history in many ways; for example, how many symphonies would Wolfgang Amadeus Mozart still have written? Among the hypotheses about the possible cause of death of the great composer is, in fact, that of a severe Trichinella infection. Mozart died in Vienna in 1791 at the age of 36 with symptoms characterized by fever, fatigue, rash, edema without dyspnea, and inflammation of the extremities, including hands and feet. The theory that has been classically most successful is that of death from poisoning by an envious colleague, Antonio Salieri (Solomon, 1995), although it has now been refuted. In 2001 J. Hirschmann, a medical doctor from the University Of Washington School Of Medicine (Seattle, USA) reported a letter dated October 7–8, 1791 from Mozart (2 months before his death) to his wife in which the musician declares what his favorite food was: "What do I smell? […] pork cutlets! Che gusto [What a delicious taste]! Now I am eating to your health!" (Hirschmann, 2001). Considering that the incubation period for trichinosis is between 8 and 50 days, Mozart may have unwittingly disclosed the cause of his death, Hirschmann stated. This is but one of dozens of hypotheses related to Mozart’s death (Drake, 1993; Jenkins, 2006; Grant and Pilz, 2011), and has also been criticized later as it presents some criticisms that are poorly compatible to a lethal trichinellosis (Dupouy-Camet, 2002).

Trichinella possibly caused the death of the great composer, but perhaps the same parasite had a positive effect on the life of a well-known actor, Yul Brynner (1920–85). The actor contracted trichinellosis in 1973 after eating at the Trader Vic’s at the Plaza Hotel, New York, from which he later received a lavish compensation of $125,000. Nevertheless, Brynner was also a heavy smoker and was diagnosed with lung cancer that led to his death on October 10, 1985. Some authors suggested that it is quite possible that the Trichinella infection decelerated the growth of cancer since the parasite is known to activate some components of the immune system of the human host (Despommier and Campbell, 2013).

Finally, can the Trichinella have slowed down the discovery of new routes and new territories?

In 1897 the Swedish explorer S.A. Andrée (1854–97) decided he would try to reach the North Pole with the help of a hydrogen-filled balloon. He obtained the necessary funds to support the efforts from the Swedish Royal Academy of Sciences, but unfortunately, the expedition ended in tragedy as his body and those of his two companions were found in 1930 with their equipment and documentation in their campsite built after the balloon crashed on the ice because of a storm. The study of Andrée’s diary was surprising as he recorded his health and illness which, years later, was identified as possible trichinellosis. In fact, Trichinella larvae were then found in the preserved flesh of two polar bears that had been shot by members of the expedition and used for food (Campbell, 1983) (Fig. 1.7). The parasite was therefore perhaps fatal for the explorers who were certainly weakened by the harsh living conditions in a cold and hostile environment. However, a recent article by Dupouy-Camet et al. (2017) noted that polar bears are a low-risk host species for Trichinella, so it cannot be ruled out that members of Andrée’s expedition died as a result of a bear attack, a thesis supported by the fact that all analgesics were found unused in the explorers’ medicine bow (Uusma, 2014).

Figure 1.7 Photo from the Andrée polar expedition of 1897. The two companions, Knut Frænkel (left) and Niels Strindberg, posing with the first polar bear killed. Public domain.

In conclusion, humanity has always had to share its path with the parasite and will probably have to do in the future despite improvements in disease prevention and treatment.

As stated by Campbell (1983), Trichinella is destined to remain with us, both in nature and in the laboratory. It is not an endangered species.

Acknowledgment

Authors wish to thank Prof. Dupouy-Camet