Outbreak of trichinellosis in Spain and Sweden due to consumption of wild boar meat contaminated with Trichinella britovi

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, Oceania, 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.

Wild Boars (Sus scrofa, L. 1758) from Castile and Leon Region (Spain): A Histopathology Survey

Wild boars are wild ungulates with a wide distribution in Europe, with a relevant role in wildlife and public health. In Spain, high (and sometimes artificial) densities of wild boars are responsible for several health problems. Regular surveys, with hunters' collaboration, are crucial to monitor these diseases. Histological analyses were performed for lung, liver, and kidneys from 72 wild boars (58 from Zamora, 16 from Palencia). Lungs were the most affected organs, mainly revealing parasitic pneumonia (34.7%). Hydropic, vacuolar, and other cellular changes (33.3%) and congestion (16.7%) were found in the liver, and only 30.6% of the wild boars presented no alterations in this organ. Regarding the kidney, non-purulent nephritis (22.2%) was the most common lesion. This study gives an overview of the health status of wild boar populations in Castile and León. Other laboratory analyses are needed to obtain definitive diagnoses of these lesions, reach other conclusions, or apply any mitigation strategies to protect animals' or consumers' health.

Epidemiology and management of foodborne nematodiasis in the European Union, systematic review 2000-2016

BACKGROUND

Foodborne nematodiasis are caused by the ingestion of food contaminated by helminths. In Europe, these diseases are present in all countries.

OBJECTIVES

To review the available data on epidemiology and management of foodborne nematodiasis in the European Union, detect any trends and determine the possible causes of the observed changes.

METHODS

A review of available literature published between 2000 and 2016 was conducted.

RESULTS

Out of 1523 cases described in the literature, 1493 cases were autochthonous and 30 cases were imported. The detected parasites were Toxocara spp (34.7%), Ascaris lumbricoides (27.1%), Trichinella spp (21.9%), Anisakis spp (15.5%) and Angiostrongylus cantonensis (0.8%).

CONCLUSIONS

Foodborne nematodiasis remains a public health challenge for the European Union. Autochthonous cases of nematodiasis present the greatest health risk within the European Union. Foodborne nematodes due to lack of hygiene in food processing are diseases that can be avoided by increasing.

Outbreak of trichinellosis related to eating imported wild boar meat, Belgium, 2014

Trichinellosis is a rare parasitic zoonosis caused by Trichinella following ingestion of raw or undercooked meat containing Trichinella larvae. In the past five years, there has been a sharp decrease in human trichinellosis incidence rates in the European Union due to better practices in rearing domestic animals and control measures in slaughterhouses. In November 2014, a large outbreak of trichinellosis occurred in Belgium, related to the consumption of imported wild boar meat. After a swift local public health response, 16 cases were identified and diagnosed with trichinellosis. Of the 16 cases, six were female. The diagnosis was confirmed by serology or the presence of larvae in the patients' muscle biopsies by histology and/or PCR. The ensuing investigation traced the wild boar meat back to Spain. Several batches of imported wild boar meat were recalled but tested negative. The public health investigation allowed us to identify clustered undiagnosed cases. Early warning alerts and a coordinated response remain indispensable at a European level.

Epidemiology, diagnosis, treatment, and control of trichinellosis

SUMMARY

Throughout much of the world, Trichinella spp. are found to be the causative agents of human trichinellosis, a disease that not only is a public health hazard by affecting human patients but also represents an economic problem in porcine animal production and food safety. Due to the predominantly zoonotic importance of infection, the main efforts in many countries have focused on the control of Trichinella or the elimination of Trichinella from the food chain. The most important source of human infection worldwide is the domestic pig, but, e.g., in Europe, meats of horses and wild boars have played a significant role during outbreaks within the past 3 decades. Infection of humans occurs with the ingestion of Trichinella larvae that are encysted in muscle tissue of domestic or wild animal meat. Early clinical diagnosis of trichinellosis is rather difficult because pathognomonic signs or symptoms are lacking. Subsequent chronic forms of the disease are not easy to diagnose, irrespective of parameters including clinical findings, laboratory findings (nonspecific laboratory parameters such as eosinophilia, muscle enzymes, and serology), and epidemiological investigations. New regulations laying down rules for official controls for Trichinella in meat in order to improve food safety for consumers have recently been released in Europe. The evidence that the disease can be monitored and to some extent controlled with a rigorous reporting and testing system in place should be motivation to expand appropriate programs worldwide.