Pikka Jokelainen

Toxoplasma gondii in wild cervids and sheep in Finland: North-south gradient in seroprevalence

A nationwide seroepidemiological study was conducted to estimate the prevalence of Toxoplasma gondii in selected wild and domestic ruminants in Finland. Serum samples from 1367 game cervids collected during the hunting season in 2008-2009 and 1940 sheep sera collected in 2008 were screened with a commercial direct agglutination test at a serum dilution of 1:40. T. gondii-specific IgG antibodies were detected in 116 (9.6%) of 1215 moose (European elk, Alces alces), 36 (26.7%) of 135 white-tailed deer (Odocoileus virginianus), 3 (17.6%) of 17 roe deer (Capreolus capreolus), and 477 (24.6%) of 1940 domestic sheep. Seropositive sheep were found in 74 (76.3%) of the 97 flocks examined. The odds of seropositivity in the adult moose was 2.9 times higher than the odds in calves; in white-tailed deer, the odds ratio was 3.2. The male moose had a significantly lower seroprevalence than the female, whereas the seroprevalence in the male white-tailed deer was higher than in the female; the odds ratios were 0.6 and 2.5, respectively. A clear geographical gradient in the seroprevalence was revealed in moose and sheep. The seroprevalences were lowest (1.6 and 8.6%, respectively) in the north and highest (24.6 and 36.4%, respectively) in the south-western regions, and ranged between these values in the other regions. In fact, the seroprevalence in moose from the south-west was not significantly different from the prevalence in white-tailed deer from the same area. Thus, the Finnish wild cervids and sheep are commonly exposed to T. gondii, especially in the southern part of the country.

Feline toxoplasmosis in Finland cross-sectional epidemiological study and case series study

Three subgroups of the Finnish cat population underwent investigation for different aspects of feline toxoplasmosis. Blood samples of 445 purebred pet cats and 45 shelter cats were screened for Toxoplasma gondii–specific immunoglobulin G antibodies with a direct agglutination test. The overall seroprevalence was 48.4%; older cats and cats receiving raw meat in their diet were more often seropositive. Fecal samples were obtained from 131 shelters cats; 2 of the cats were found shedding T. gondii–like oocysts, and the oocysts shed by 1 of the 2 were confirmed as T. gondii with polymerase chain reaction. Among 193 cats submitted for necropsy during a 3.5-year period, 6 (3.1%) had been diagnosed with generalized toxoplasmosis and were retrospectively further investigated. The main pathological lesions included acute interstitial pneumonia, acute necrotizing hepatitis, and nonsuppurative meningoencephalitis with glial granulomas. Immunohistochemical staining demonstrated a mild to massive parasite burden in tissues with pathological lesions as well as in unaffected tissues. The results of the direct multilocus genotyping of T. gondii parasites detected were consistent with endemic genotype II, and the causative parasite strains were isolated from 2 of the generalized toxoplasmosis cases. The results indicate that cats in Finland commonly encounter T. gondii and contribute to the environmental oocyst burden, while the endemic genotype II can also prove fatal to the parasite’s definitive host. Preventing feline T. gondii infections is not only of public health importance but also a welfare issue for the cats themselves.

NATURAL TOXOPLASMA GONDII INFECTIONS IN EUROPEAN BROWN HARES AND MOUNTAIN HARES IN FINLAND: PROPORTIONAL MORTALITY RATE, ANTIBODY PREVALENCE, AND GENETIC CHARACTERIZATION

In material examined postmortem in Finland from May 2006 to April 2009, acute generalized toxoplasmosis was the immunohistochemically confirmed cause of death in 14 (8.1%) of 173 European brown hares (Lepus europaeus) and four (2.7%) of 148 mountain hares (Lepus timidus). Sera from 116 of the European brown hares and 99 of the mountain hares were screened with a commercial direct agglutination test for Toxoplasma gondii-specific IgG antibodies at a dilution of 1:40. All sera from cases of fatal toxoplasmosis had high titers of antibodies reactive to T. gondii. In contrast, none of 107 European brown hares and four (4%) of 96 mountain hares that died of other causes were antibody-positive. The proportional mortality rates and the T. gondii antibody prevalences among noncases differed significantly between the two host species (P<0.05). Direct genetic characterization of the causative agent was performed on DNA extracted from formalin-fixed, paraffin-embedded tissue of the hares with fatal toxoplasmosis. Based on the results with six microsatellite markers (B18, TUB2, TgM-A, W35, B17, and M33; all six in 15 cases and four in three cases), all the cases were caused by T. gondii genotype II; the size of the PCR product at the seventh marker (M48) varied (213–229 base pairs). The presence of T. gondii genotype II, which is endemic in Europe, is now confirmed in Finnish wildlife: Natural infections with T. gondii parasites belonging to this widespread genotype caused fatal generalized toxoplasmosis in the two species of wild hares.

Echinococcus infections in the Baltic region

In the Baltic countries, the two zoonotic diseases, alveolar echinococcosis (AE) caused by Echinococcus multilocularis, and cystic echinococcosis (CE) caused by Echinococcus granulosus, are of increasing public health concern. Observations from Estonia, Latvia and Lithuania indicate that the distribution of both parasites is wider in the Baltics than previously expected. In this paper, we review and discuss the available data, regarding both parasitoses in animals and humans, from the Baltic countries and selected adjacent regions. The data are not easily comparable but reveal a worrisome situation as the number of human AE and CE cases is increasing. Despite improvements in diagnostics and treatment, AE has a high morbidity and mortality in the Baltic region. For the control of both zoonoses, monitoring transmission patterns and timely diagnosis in humans as well as the development of local control programs present major challenges.

Farmed wild boars exposed to Toxoplasma gondii and Trichinella spp.

The meat of wild boar (Sus scrofa L.) can be a source of human infections with zoonotic parasites Toxoplasma gondii and Trichinella spp. We screened 197 wild boar sera collected at slaughter from 25 Finnish farms in 2007-2008 for serological evidence of infections with these parasites. Using a commercial direct agglutination test at a serum dilution of 1:40, T. gondii-specific IgG antibodies were detected in 65 (33.0%) samples, on 14 (56.0%) farms. Females, animals older than 24 months, animals of small herds, and animals originating from south-western parts of Finland were more often T. gondii-seropositive than were males, younger animals, animals of larger herds, and animals originating from the north and east, respectively. Four (2.0%) of the sera, originating from three (12.0%) farms, tested Trichinella-seropositive with an in-house ELISA and a conservative cut-off for seropositivity. One farm had both T. gondii- and Trichinella-seropositive animals. Taken together, an infection source had been present on 16 (64.0%) farms, and 69 (35.0%) of the 197 farmed wild boars intended for human consumption had specific serological evidence of exposure to a zoonotic parasite.

Acute fatal toxoplasmosis in three Eurasian red squirrels (Sciurus vulgaris) caused by genotype II of Toxoplasma gondii.

Toxoplasma gondii parasites belonging to endemic genotype II caused fatal infection in three (16%) of 19 Eurasian red squirrels (Sciurus vulgaris) sent for necropsy in Finland between May 2006 and April 2009. The liver, spleen, and lungs were the organs most affected in all three cases, and high numbers of T. gondii parasites were visualized immunohis-tochemically in all the tissue samples available from them. The genotyping of the parasite strains was based on the results of analysis of length polymorphism at six microsatellite markers (B18, TUB2, TgM-A, W35, B17, and M33). The length of the PCR product at the additional seventh marker (M48) was 233 base pairs from the first two cases that were found dead together, suggesting a common infection source, and 215 base pairs from the third. Eurasian red squirrels may be exceptionally susceptible to T. gondii infection.

Seroprevalence of Toxoplasma gondii in free-ranging wild boars hunted for human consumption in Estonia

BackgroundAlthough the prevalence of human Toxoplasma gondii infections is high in Estonia, no information is available on the prevalence of infections in the local animal populations. Wild boars are a good indicator species for estimating the prevalence and spread of T. gondii and were thus investigated in this nationwide cross-sectional study. Volunteer hunters sampled cardiac or skeletal muscle of 471 wild boars legally hunted for human consumption in Estonia during the hunting season of 2012–2013. Serosanguineous meat juice samples were obtained from thawed tissue samples, diluted 1:40, and screened for specific anti-T. gondii IgG antibodies with a commercial direct agglutination test.ResultsAlmost one-quarter (113; 24%) of the wild boars examined were seropositive for T. gondii. The seroprevalence did not differ significantly between age groups or sexes. The seroprevalence was lowest in Viljandimaa, which is located in the southern part of Estonia. In other counties, the infection was evenly prevalent.ConclusionsIn Estonia, wild boars are commonly exposed to T. gondii, which is endemic and widespread. The consumption of raw or undercooked meat of Estonian wild boars may pose an infection risk to humans and other hosts.

Feline intestinal parasites in Finland: prevalence, risk factors and anthelmintic treatment practices

The aim of this study was to estimate the prevalence of feline intestinal parasites in Finland and to determine the possible risk factors for infection. Altogether 411 feline fecal samples were analyzed with a flotation method to reveal helminth eggs and protozoan oocysts. Of the samples, 402 were also screened for Giardia species antigens with a commercial enzyme-linked immunosorbent assay kit. The cat owners completed a questionnaire. Toxocara cati prevalence was 5.4% and Toxascaris leonina 0.2%. Taenia species eggs were found in 1.5% of the samples and Isospora felis in 0.7%, whilst 3.2% of the samples tested positive for Giardia species antigen. Risk factors for Toxocara/Toxascaris species infection included being a non-pedigree cat, having access to the outdoors, living outside of the cities and receiving home-made food. Pedigree cats were at greater risk of contracting Giardia duodenalis. The majority of the cat owners (62.4%) treated their cat with anthelmintics 2–4 times per year.

Seroprevalence of and Risk Factors for Toxoplasma gondii Infection in Cats in Estonia

In Estonia, northeastern Europe, Toxoplasma gondii seroprevalence in humans has not declined, in contrast to many other countries. The reasons for this are unknown. Domestic cats are important hosts in the epidemiology of the parasite, but information on local feline T. gondii infections has been lacking. An epidemiological cross-sectional study was conducted to estimate the seroprevalence of T. gondii and the risk factors associated with seropositivity in cats in Estonia. Surplus from blood samples that had been collected for unrelated diagnostic purposes from 306 pet cats and 184 shelter cats were analyzed for anti-T. gondii immunoglobulin G antibodies by using a direct agglutination test. Two questionnaires were designed to reveal relevant risk factors for seropositivity. The overall seroprevalence of T. gondii in cats in Estonia was 60.8%. Older age, outdoor access, hunting, living outside the city in the countryside, and not being a purebred cat were among the risk factors associated with seropositivity. T. gondii is highly prevalent in domestic cats in Estonia. This suggests that the environment has been contaminated with T. gondii. Seropositivity indicates previous oocyst shedding, and most of the cats had outdoor access. The increase in T. gondii seroprevalence with age indicates acquired infections, and most of the risk factors were lifestyle-related. Cat owners could diminish the risk of T. gondii infection and also limit the spread of the parasite by not allowing their cats to roam free.

FREE-RANGING EURASIAN LYNX (LYNX LYNX) AS HOST OF TOXOPLASMA GONDII IN FINLAND

We investigated the presence of Toxoplasma gondii infections in Eurasian lynx (Lynx lynx) in Finland by analyzing samples from 337 lynx that were legally hunted during the 2010–2011 season and by performing a retrospective nationwide database search of postmortem toxoplasmosis diagnoses in this species. We detected specific anti-T. gondii IgG antibodies in 290 (86.1%) of the 337 lynx. The method used was a direct agglutination test, and samples positive at the used dilution 1:40 were defined as antibody positive. Older lynx had 14.3 times higher odds of being antibody-positive than did lynx of the presumed age of 7–10 mo, and lynx weighing >15 kg had 16.7 times higher odds of being antibody positive than did those ≤15 kg. Lynx from the southwest were more often antibody positive, with an odds ratio 6.3, than lynx from the northeast. None of the 332 fecal samples available was positive for the presence of T. gondii-like oocysts with a quantitative MgSO4 flotation technique, and none of the 167 free-ranging Eurasian lynx examined postmortem by veterinary pathologists from January 2000 to May 2010 had died from toxoplasmosis. Although Finnish lynx were confirmed to commonly encounter T. gondii, we found no evidence of an ongoing contribution to the environmental oocyst burden nor of the lynx dying from the infection.