Helminths of wild boar in the isolated population close to the northern border of its habitat area

One hundred wild boars (Sus scrofa) from a geographically isolated population on the island Saaremaa of western Estonia were examined for visceral helminths. Seven helminth species, Metastrongylus pudendotectus, M. salmi, M. elongatus, Ascaris suum, Trichuris suis, Dicrocoelium dendriticum and Taenia hydatigena larva, were found. The predominant helminths discovered were lung nematodes (prevalence 82%, mean intensity 96.2 per animal). A significant negative correlation was observed between the weight of wild boars and the number of lungworms and helminth species. The number of helminth species found in the wild boar population on the island was lower compared to that of the adjacent mainland.

Molecular epidemiology of Trichinella spp. in three Baltic countries: Lithuania, Latvia, and Estonia

Meat of domestic pigs and wild boars has been the significant source of emerged human trichinellosis in Lithuania, Latvia, and Estonia over the past two decades. However, there is very little known on the occurrence of Trichinella spp. in main wildlife reservoirs and its transmission in domestic and sylvatic cycles in these countries. The present study demonstrated considerably higher endemicity of Trichinella spp. in main sylvatic reservoirs (28.9-42% in foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in all three countries than previously reported. Molecular identification of Trichinella larvae from more than 500 sylvatic and domestic animals revealed four Trichinella species (Trichinella spiralis, Trichinella britovi, Trichinella nativa, and Trichinella pseudospiralis) sympatric in a relatively small area and several as the first records for the respective countries. The nonencapsulating T. pseudospiralis is found for the first time in the Eastern Europe. Sylvatic T. britovi was found in domestic pigs in Lithuania and Latvia (16 and 57.1%, respectively) and only in these countries, domestic T. spiralis was detected in sylvatic animals in areas where domestic trichinellosis was registered. The study suggests that transmission of Trichinella between domestic and sylvatic cycles in Lithuania and Latvia is favored by improper human behavior, e.g., pig and slaughter waste management.

Distribution of Toxocara infection in the environment and in definitive and paratenic hosts in Estonia

The aim of the study was to elucidate the distribution and possible transmission routes of Toxocara spp. infection in Estonia. Out of 454 faecal and sand samples collected from park lawns and sandpits in the town of Tartu, 19 were Toxocara positive (4.2%). Out of the 45 sandpit samples 17.8% were Toxocara positive. Cat faeces was found in 21 sandpit samples. Parasitological necropsies were performed on 41 euthanised stray dogs and 27 cats in the Tallinn Dog Home. Additionally, 13 wild free-roaming brown rats (Rattus norvegicus) were captured from the Tallinn Dog Home territory, necropsied and studied for the presence of Toxocara larvae. Toxocara canis adults were found in 14.6% of the dogs and Toxocara cati (syn. mystax) adults in the small intestines of 48.2% of the cats examined. Larval infection was detected in the kidney and liver in 5 dogs (12.2%). Our study demonstrated only low-level larval Toxocara infections in adult dogs. Toxocara larvae were not found in cats and brown rats. According to the results of this study, cats more often carry Toxocara infection than dogs. Under our conditions, stray and free-roaming cats are the main contaminators of the environment with Toxocara eggs. Children playing in sandpits are the main risk group for larval toxocarosis.

Epidemiological investigations on Trichinella infections in farmed fur animals of Estonia

Farming of fur animals represents an important income in Estonia. Even though Trichinella worms does not induce a symptomatic disease in carnivores, the carcasses of skinned animals can increase the biomass of the parasite in the environment, if they are not properly destroyed. The aim of the present survey was to study the prevalence of Trichinella worms in farmed fur animals of Estonia. Of 281 muscle samples from blue foxes (Alopex lagopus), silver foxes (Vulpes vulpes fulva), minks (Mustela vison) and raccoon dogs (Nyctereutes procyonoides), which were collected in eight farms, Trichinella larvae have been detected in 21 animals (8%) from two farms by HCl-pepsin digestion. The highest number of larvae per gram of muscle was found in the front limb muscles. Larvae of the 21 isolates have been identified as Trichinella britovi or Trichinella nativa by a multiplex-PCR analysis.

HELMINTHOLOGIC SURVEY OF THE WOLF (CANIS LUPUS) IN ESTONIA, WITH AN EMPHASIS ON ECHINOCOCCUS GRANULOSUS

Carcasses of 26 wolves were collected during the 2000/2001 and 2003/2004 hunting seasons and examined for helminths. Thirteen helminth species were recorded: one trematode (Alaria alata), seven cestodes (Diphyllobothrium latum, Mesocestoides lineatus, Taenia hydatigena, Taenia multiceps, Taenia ovis, Taenia pisiformis, and Echinococcus granulosus), and five nematode species (Uncinaria stenocephala, Toxascaris leonina, Toxocara canis, Trichinella nativa, and Trichinella britovi). The most common species were A. alata and U. stenocephala. Mature Echinococcus granulosus was found and described for the first time in Estonia, and its identity verified using PCR-RFLP analysis. Sequencing a fragment of the mitochondrial DNA NADH dehydrogenase 1 (mtND1) gene showed that the E. granulosus strain from Estonia was identical to strain G10, recently characterized in reindeer and moose in Finland.

Epidemiological studies on animal and human trichinellosis in Estonia

From 1992 to 1999, muscle samples from 814 sylvatic animals and 1,173 domestic and synanthropic animals were collected in 15 districts of Estonia; the prevalence of trichinellosis ranged from 1.0% to 79.4% for sylvatic animals and from 0.6% to 24.5% for domestic or synanthropic animals and for animals from fur-bearing farms. The most important reservoirs of Trichinella in nature were the raccoon dog, the red fox, the lynx and the wolf. Three species of Trichinella (T. spiralis, T. nativa, and T. britovi) were identified by several types of PCR-based analyses. Meat from sylvatic animals was the main source of Trichinella infection for humans.

Intraspecific and interspecific variation in the second internal transcribed spacer (ITS-2) sequence for Metastrongylus (Nematoda: Metastrongyloidea) detected by high resolution PCR-RFLP

Metastrongylus species are important parasites of free-range pigs and wild boar, but little is known about the genetic make-up of natural populations. This study was undertaken to examine sequence variation in the internal transcribed spacer 2 of ribosomal DNA within and among three species of Metastrongylus using PCR-linked restriction fragment length polymorphism analysis. In contrast to many other species of bursate nematodes, significant intraspecific variation was detected in restriction fragment length polymorphism profiles among individual worms. In spite of this, it was possible to identify the three species by their distinctive restriction profiles. The findings suggest that the internal transcribed spacer 2 region should be useful for analysing population variation within Metastrongylus species.

Distribution of sylvatic species of Trichinella in Estonia according to climate zones

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.

Concurrent infection with sibling Trichinella species in a natural host

Random amplified polymorphic DNA (RAPD) analysis of individual Trichinella muscle larvae, collected from several sylvatic and domestic animals in Estonia, revealed concurrent infection of a racoon dog with Trichinella nativa and Trichinella britovi. This finding provides strong support for their taxonomic ranking as sibling species. These 2 species appear uniformly distributed among sylvatic animals through Estonia, while Trichinella spiralis appears restricted to the domestic habitat.