Outbreak of trichinosis in Ontario secondary to the ingestion of wild boar meat

From wildlife to humans: The global distribution of Trichinella species and genotypes in wildlife and wildlife-associated human trichinellosis

Zoonotic nematodes of the genus Trichinella are foodborne parasites that have a global distribution in wild carnivores and omnivores, with spillover and spillback into domestic livestock and people, with concomitant trade and health consequences. Historically, most human cases were linked to domestic pigs infected with Trichinella spiralis, but under current high biosecurity swine production in many countries, wildlife have become a more important source of human trichinellosis. The aim of this review is to update the global distribution of Trichinella species and genotypes reported in wildlife, as well as reported human outbreaks from the consumption of wildlife. Using several online databases and by "snowballing" references, hundreds of reports of Trichinella spp. in wildlife published between January 1991 and December 2023 provide an important update to the host and geographic range for each of the recognized 13 species/genotypes, grouped by continent. Surveillance effort was highest in Europe and North America, while Africa, Asia, Central and South America have had limited surveillance, in some instances with human cases serving as sentinels of transmission in a region. Dozens of human outbreaks are described, with wild boars (Sus scrofa) being the most frequently implicated wildlife species in human outbreaks globally. Bears are an important source of infection in North America, for wildlife tourism, and importation of bear meat has also been implicated in multicountry outbreaks. The largest study limitation was the dearth of molecular identification of larvae in both wildlife surveillance studies and human outbreaks, particulary in under-studied regions. We highlight the need for enhanced molecular epidemiological approaches to outbreaks of this important foodborne parasite, and emphasize the need for a One Health approach to manage Trichinella spp. which transmit among terrestrial and marine wildlife (including migratory birds), pigs, horses, and people, often across large geographic scales and borders.

A Review of Zoonotic Infection Risks Associated with the Wild Meat Trade in Malaysia

The overhunting of wildlife for food and commercial gain presents a major threat to biodiversity in tropical forests and poses health risks to humans from contact with wild animals. Using a recent survey of wildlife offered at wild meat markets in Malaysia as a basis, we review the literature to determine the potential zoonotic infection risks from hunting, butchering and consuming the species offered. We also determine which taxa potentially host the highest number of pathogens and discuss the significant disease risks from traded wildlife, considering how cultural practices influence zoonotic transmission. We identify 51 zoonotic pathogens (16 viruses, 19 bacteria and 16 parasites) potentially hosted by wildlife and describe the human health risks. The Suidae and the Cervidae families potentially host the highest number of pathogens. We conclude that there are substantial gaps in our knowledge of zoonotic pathogens and recommend performing microbial food safety risk assessments to assess the hazards of wild meat consumption. Overall, there may be considerable zoonotic risks to people involved in the hunting, butchering or consumption of wild meat in Southeast Asia, and these should be considered in public health strategies.

Disease risks associated with free-ranging wild boar in Saskatchewan

This study investigated the disease status of Saskatchewan's feral wild boar population. Whole carcasses, tissue samples, and/or serum from 81 hunter-killed boars from Saskatchewan were submitted to the Canadian Wildlife Health Cooperative (CWHC) between 2009 and 2014. Serological tests were negative for PRRS, H1N1, and H3N2 swine influenza, PCV-2, and TGE/PRCV in 22/22 boars and for Toxoplasma gondii and Mycoplasma hyopneumoniae in 20/20 boars. Of 20 boars whose sera were tested 20 were positive for Actinobacillus pleuropneumoniae, with 7 positive for, among other strains, serotype 14; 16 were positive for Lawsonia intracellularis, 1 was positive and 6 were suspicious for Salmonella spp. Polymerase chain reaction tests were negative for PRRS and PCV2 in 58/58 boars and positive for Torque teno virus in 1/8 boars. Digestion assays were negative for Trichinella spp. in 22/22 boars. The high seroprevalence of A. pleuropneumoniae serotype 14 is noteworthy as this serotype has not been previously reported in North America.

Meat from wild boar (Sus scrofa L.): a review

Wild boar is a species that is utilised for food and sport hunting throughout the world. Recent increases in natural populations and the potential of farming wild boars have stimulated interest in this species as a meat producer. Compared to domestic pigs, wild boars present a higher degree of carcass fatness and larger loin areas, more slow-twitch oxidative (I) and fast-twitch oxidative glycolytic (IIA) and less fast-twitch glycolytic (IIB) muscle fibres, and darker, less tender and leaner meat. Differences in diets might contribute to differences in cooked meat flavour and fatty acid composition between wild boars and domestic pigs. Higher α-tocopherol concentrations in wild boar might extend its meat shelf-life. Mechanical massaging of muscles, vacuum package ageing and addition of marinates have been attempted to tenderise wild boar meat. Further research on hunting protocols for wild boar, and value-added products from its meat, are needed.

Fever and Periorbital Edema: A Review

Fever and periorbital swelling are the manifestation of a broad array of diseases. Among them are emergency situations, which need prompt physician input. Swiftly formulating a differential diagnosis approach is crucial. Diseases causing fever and periorbital edema are either local or systemic. Nevertheless, their impact can be systemic if they evade diagnosis. Infectious diseases and non-infectious diseases (inflammatory and allergic diseases, autoimmune diseases, neoplastic diseases, and trauma) can all lead to fever and periorbital edema. A meticulous history and physical examination in association with targeted tests against the presented spectrum of diseases (specific serological tests, radiological tests, cultures taken from the surface of the periorbital area and other relevant areas, and skin biopsy for histological and microbiological examination) will clarify the diagnosis.

National occurrence reporting of Trichinella and trichinellosis using a computerized database

Historical and contemporary national data on the occurrence and distribution of Trichinella and trichinellosis in people, domestic animals and wildlife in Canada have been incorporated into a computerized database, the Canada Database of Animal Parasites (CDAP). This database was established in 1998, and contains similar information on several other helminth and protozoan parasites which are of importance in animal health, human health, food safety or trade. The CDAP is a unique assemblage of national information on parasite occurrences, not available from any other single source. This paper describes the CDAP, with emphasis on sources of data, database structure and outputs, logistical issues associated with database development and maintenance, and the application of the CDAP to Trichinella surveillance at a national level. It is suggested that the CDAP, or a similar approach, could be applied in other countries for assembling data on Trichinella and trichinellosis.

Trichinellosis: the zoonosis that won't go quietly

Trichinellosis, is normally not included among those regarded as emerging zoonoses because it has been a public health threat for more than 150 years. However, its dramatic re-emergence in many areas around the world over the past 10-20 years, inspite of a century of veterinary public health efforts to control and eradicate it, justifies it being included in this group. The reasons for this re-emergence are diverse, and include human pertubation and manipulation of ecosystems, war and political turmoil, rapidly changing food distribution and marketing systems, and even, surprisingly, rising affluence in developing countries. These influences, and their impact on the epidemiology of both domestic and sylvatic trichinellosis, are discussed, along with recommendations for confronting this altered status as a public health threat.

Experimental trichinellosis in reindeer

Six female reindeer calves were inoculated intraruminally with various doses of Trichinella muscle larvae. Four calves were inoculated with T. nativa, receiving 15,000 (n = 1), 5,000 (1), and 2,500 (2) larvae each. Two calves were inoculated with 5,000 T. spiralis larvae each. Blood samples were collected twice per week for total white blood cell (WBC) and differential counts and for serology using enzyme-linked immunosorbent assay (ELISA) based on T. spiralis excretory-secretory antigen. On day 56, the calves were slaughtered and muscle samples were examined according to the standard digestion method for Trichinella larvae. Blood samples were also collected twice a week from 4 uninoculated, but otherwise similar, reindeer calves corralled separately. Both the total WBC and eosinophil counts of the inoculated animals were, on average, higher during the experimental period. All the inoculated calves seroconverted, showing an increase in the optical density (OD) in the ELISA starting between day 23 and day 27 postinoculation. Very few muscle larvae (<0.08 larvae/g [lpg]) were to be found from the animals inoculated with T. nativa, but about 4 and 6 lpg were recovered from the masseter muscles of those inoculated with T. spiralis.

Eosinophilia in the returning traveler

Eosinophilia is one of the most common laboratory abnormalities seen in the returning traveler. Although elevations in peripheral eosinophil levels can occur in a wide variety of disease processes, worldwide, helminth parasites are the major group of infectious agents responsible for eosinophilia. While often directed at helminth infections in their early stages of clinical evolution, the approach to the evaluation of the returning traveler with eosinophilia must consider the many causes of eosinophilia including those not casually related to travel. This article reviews the major parasitic causes of eosinophilia and provides a systematic approach to the evaluation of eosinophilia following travel.