Exposure of the Gulf of St. Lawrence grey seal Halichoerus grypus population to potentially zoonotic infectious agents

Leptospirosis in marine mammals: An in-depth look at an underexplored ecosystem

Marine mammals are a diverse group that live in, or are fully dependent upon, the ocean and marine food chain. Infection by Leptospira bacteria has been documented in this group of animals and may cause renal pathology, which for some species can lead to morbidity and mortality. Despite its impact on animal health and relevance as a zoonotic pathogen, important aspects of leptospirosis in marine mammals are still minimally explored. In this context, we conducted a systematic review to better understand this infection in marine mammals worldwide. A systematic review of scientific databases was conducted, resulting in 72 papers. They were classified into twelve categories, such as clinical signs, serologic and molecular identification, geographical localization, and other relevant information. North America stands out as the focus for most of the global research on this topic (70.8 % of publications). The most common clinical signs were depression, anorexia, polydipsia, dehydration, vomiting, muscle tremors, abdominal pain, and sometimes seizure-like neurologic signs. Many of these clinical signs can be attributed to Leptospira-related renal failure and electrolyte imbalances. While severe disease and death were often reported, reports of an asymptomatic state in some individuals suggest a potential asymptomatic infection and highlight the possible role of marine mammals as disseminators of Leptospira spp. in a highly fluid ecosystem. Serology was the most used diagnostic method (77.8 %), and Pomona, Gryppotyphosa, and Icterohaemorrhagiae were the most frequently identified serogroups. Regarding direct detection methods, PCR was the most commonly used (38.8 %), while culture was used in 25 % and IHC in 23.6 % of studies. Based on genetic characterization, Leptospira interrogans was the most commonly detected species. To understand the epidemiology of this complex disease, a review of multiple studies demonstrated the importance of an integrative approach, including pathological, biochemical, molecular and phylogenetic analyses, not only to enrich knowledge about marine microbiological biodiversity but also to clarify important key points on the epidemiology and pathophysiology of this important zoonosis in an ecosystem that is still so little explored.

Epidemiology of Trichinella in the Arctic and subarctic: A review

The finding of Trichinella in the Arctic was foreseen because captive polar bears and arctic foxes had been found infected during the first decades of the 20th century. Human trichinellosis outbreaks were reported to have taken place in 1944 in Franz Josef Archipelago and 1947 in Greenland, and previous outbreaks in Greenland also appeared to have been trichinellosis. Now, it is known that Trichinella parasites thrive in the Arctic and subarctic and pose a risk for public health. We collated the available information, which show that infection prevalences are high in many animal host species, and that outbreaks of human trichinellosis have been described also recently. The species diversity of Trichinella in the Arctic and subarctic is relatively high, and the circulation is in non-domestic cycles with transmission by predation, scavenging and cannibalism. There are also sporadic reports on the synanthropic species Trichinella spiralis in arctic wild mammals with little known or assumed contact to potential synanthropic cycles. In this paper, we summarize the knowledge on epidemiology of Trichinella parasites in the circumpolar Arctic and subarctic regions, and discuss the challenges and solutions for their control.

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Trichinella infection is common in wild animals in the Arctic and subarctic regions.

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The high prevalence of Trichinella infection in some arctic marine mammal species suggests a marine cycle.

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Outbreaks of human trichinellosis have been described, and public health importance still remains obvious.

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In this review, we had access to the large amount of Trichinella literature published in the Russian language.