Distribution of Sylvatic Species of Trichinella in Estonia According to Climate Zones

Abstract

A survey on trichinellosis among sylvatic and domestic animals from Estonia revealed the presence of Trichinella nativa (Tn), Trichinella britovi (Tb), and Trichinella spiralis (Ts). Muscle samples were collected from 776 sylvatic and 1,086 domestic animals. Muscle larvae from 52 of the 74 positive samples were identified, using random-amplified polymorphic DNA analysis; 19 samples showed Tn, 27 samples Tb, and 4 samples Ts. A raccoon dog (Nyctereutes procyonoides) and a red fox (Vulpes vulpes) were infected with both Tn and Tb. Of the 19 animals infected with Tn, 16 (84%) were collected from the central-eastern regions of the country, east of the isotherm -5 C in January. Of the 27 animals infected with Tb, 22 (81%) were collected from the western regions of the country, west of the isotherm -4 C in January. Trichinella spiralis seemed to be present only in a focus (a fur-bearing animal farm) on Hiiumaa Island. These results can be used to support the hypothesis of a relationship between the distribution of Tn and Tb and the environmental temperature; they are also indicative of the importance of long-term survival of muscle larvae in host carcasses in the life cycle of these 2 species. In Estonia, the isotherms -4 and -6 C in January could be considered a thermic barrier for the distribution of Tn and Tb, respectively.

Ecological characterization of bat species distributions in Michoacán, México, using a geographic information system

“…The effect of temperature on species distributions has been documented for a wide variety of organisms, including birds (Rabinovich & Rapoport, 1975), parasites (Pozio et al ., 1998), macroinvertebrates (Lowe & Hauer, 1999) and microbes (Nishiguchi, 2000). Bojórquez‐Tapia et al .…”

High prevalence ofTrichinella nativainfection in wolf(Canis lupus)populations of Tvier and Smoliensk regions of European Russia

“…In 1993, in the European regions of Russia, the prevalence of infection was reported to be of the -6°C isotherm in January, which is the southern limit of the distribution of this Trichinella species (Shaikenov, 1992;Pozio et al, 1998). The presence of T. britovi in a wolf could be related to a passive introduction of the parasite in a domestic animal from a temperate region of Russia followed by transmission to wildlife.…”

Environmental Aspects of Zoonotic Diseases

“…Both characteristics play a major role in the distribution of this parasite. In sylvatic animals, T. nativa was found mostly in central-eastern regions of the country (east of isotherm −5°C) while T. britovi was detected in western parts of the country (west of isotherm −4°C), both isotherms being measured in January (the winter coldest month) (Pozio et al, 1998). In the other extreme, T. britovi has been reported to survive in frozen carrion for up to one year, while the T. nativa and Trichinella genotype T6 for up to several years, all maintaining potential infectivity for future hosts (Dick et al, 2001;.…”