Brian Lassen

Eimeria and Cryptosporidium in Estonian dairy farms in regard to age, species, and diarrhoea

Eimeria and Cryptosporidium are among the most common bovine parasites in the world, but little is known about them in Estonia. Basic field research is needed to gain insight into pathogen dynamics, providing knowledge for veterinarians and research. A survey of 45 Estonian dairy farms in 15 counties was carried out between 2006 and 2007. Three age groups: <3, 3-12, and >12 months old animals were sampled. Collected faeces were examined by quantitative flotation and Ziehl-Neelsen contrast staining, and species examined morphologically. Selected samples containing Cryptosporidium were additionally examined by polymerase-chain-reaction (PCR) and sequencing to determine genotypes. Twelve species of Eimeria were identified, seven previously unknown in Estonia. Main species in samples were E. bovis (30%), E. zuernii (23%), and E. ellipsoidalis (14%). All herds were infected and animals aged 3-12 months were more commonly infected with Eimeria oocysts (63%) than any other group. Calves <3 months shed most oocyst, but high counts were rare. A negative association (slope=-0.16, p<0.001) was found between the number of animals infected with Eimeria and the age category. Cryptosporidium were detected in 84% of the farms, and C. andersoni and C. parvum were successfully identified. Though prevalences of Cryptosporidium in the age groups were similar to the sample prevalence (30%) an increase in the infections was found with increasing age (p<0.001). Higher diarrhoea scores were negatively associated with Eimeria spp. infection (slope=-0.08, p<0.05), whereas Cryptosporidium could not be associated with the presence of diarrhoea. Frequent low intensity infections of animals in all age groups with both parasites apply a constant stress on the animals with impact on health and production. The Estonian results are different compared to available studies in regard of: older animals commonly being infected, finding of modest oocyst counts, and distribution of Eimeria species.

Estimation of the economical effects of Eimeria infections in Estonian dairy herds using a stochastic model.

In this study, a stochastic predictive model stimulating a constant infection pressure of Eimeria was used to estimate production outcome, economic, and effects of treatment decisions in a dairy herd of 100 cows. The intestinal parasite cause problems mainly in calves, and is known to have long term effects on the growth rate, and in severe cases can result in mortalities. Due to the inconspicuous nature of the parasite, the clinical signs and sub-clinical manifestations it may produce can be overlooked. Acquired data from literature and Estonian dairy farms were implemented in the SimHerd IV model to simulate three scenarios of symptomatic treatment: no calves treated (NT), default estimate of the current treatment strategy (DT), and all calves treated (AT). Effects of metaphylactic treatment were studied as a lowering of the infection pressure. Delay in the age for beginning of insemination of heifers was the effect with the largest economic impact on the gross margin, followed by calf mortality and reduction in growth rate. Large expenses were associated with the introduction of replacement heifers and feeding of heifers as a result of the delay in reaching a specific body weight at calving. Compared to the control scenarios, with no effects and treatments of Eimeria, dairy farmers were estimated to incur annual losses ranging 8-9% in the balanced income. Providing metaphylactic drugs resulted in an increased gross margin of 6-7%. Purchase of new heifers compensated for some production losses that would otherwise have enhanced expenses related to Eimeria. The simulation illustrates how effects of Eimeria infections can have long lasting impact on interacting management factors. It was concluded that all three simulated symptomatic treatment regimes provided only small economic benefits if they were applied alone and not in combination with lowering of infection pressure.

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.

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.

Serological Evidence of Exposure to Globally Relevant Zoonotic Parasites in the Estonian Population.

We investigated Estonian population and its selected subgroups for serological evidence of exposure to Ascaris lumbricoides, Echinococcus spp., Taenia solium, Toxocara canis, Toxoplasma gondii, and Trichinella spiralis. Serum samples from 999 adults representing general population, 248 children aged 14–18, 158 veterinarians, 375 animal caretakers, and 144 hunters were tested for specific immunoglobulin G antibodies against the selected parasites using commercial enzyme immunoassays (ELISA). Sera yielding positive or twice grey zone Echinococcus spp, T. solium, T. canis, and T. spiralis results were subjected to western blot (WB) analysis. In the general population, based on the ELISA results, the A. lumbricoides seroprevalence was 12.7%, Echinococcus spp. seroprevalence was 3.3%, T. solium seroprevalence was 0.7%, T. canis seroprevalence was 12.1%, T. gondii seroprevalence was 55.8%, and T. spiralis seroprevalence was 3.1%. Ascaris lumbricoides seroprevalences were higher in children and in animal caretakers than in the general population, and T. canis seroprevalence was higher in animal caretakers than in the general population. Compared with the general population, Echinococcus spp. seroprevalence was higher in children. By contrast, T. gondii seroprevalence was higher in animal caretakers, and lower in children, than in the general population. In the general population, the WB-confirmed Echinococcus spp. seroprevalence was 0.5%, T. solium cysticercosis seroprevalence was 0.0%, Toxocara spp. seroprevalence was 14.5%, and Trichinella spp. seroprevalence was 2.7%. WB-confirmed Toxocara spp. seroprevalence was higher in animal caretakers than in the general population. We found serological evidence of exposure to zoonotic parasites in all tested groups. This calls for higher awareness of zoonotic parasitic infections in Estonia.

Cryptosporidiosis – an occupational risk and a disregarded disease in Estonia

BackgroundCases of cryptosporidiosis have not been officially reported in Estonia after the year 2000, and the disease appears to be either under-diagnosed or under-reported.FindingsBased on a human case of cryptosporidiosis contracted during faecal sampling in dairy farms, cattle considered to be sources of infection were analysed for Cryptosporidium spp. by a modified Ziehl Neelsen technique and molecular typing. C. parvum subtype IIaA16G1R1 was detected from the human case and from calves from one of nine farms enrolled in the study providing strong circumstantial evidence of zoonotic transmission from calves to humans.ConclusionCryptosporidiosis presents an occupational risk to people with cattle contact, and may also be a risk to the human population in general. Thus increased public and medical awareness is warranted.

Neospora caninum in Estonian dairy herds in relation to herd size, reproduction parameters, bovine virus diarrhoea virus, and bovine herpes virus 1.

Cows infected with the tissue parasite Neospora caninum (Nc) are more likely to abort or give birth to calves with neurological disorders. The known infection routes are transplacentally and by consumption of oocysts shed by the definitive host, the dog. It has been hypothesised, that dormant stages of persistent Nc infection may be reactivated by immunosuppression mechanisms such as pathogenic invasions as bovine herpes virus 1 (BHV1) and bovine virus diarrhoea virus (BVDV). The study was set to give the first prevalence data on Nc from Estonian dairy herds in both animal as well as herd level. In addition, association between herd size and Nc, and association of Nc with abortion incidence (Ab), stillbirth incidence (Sb), insemination index (II), and calving interval (CaI) in the presence of BHV1 and BVDV was studied. Blood samples from 1973 animals from 100 herds were collected in 2006-2008, and 320 bulk tank milk (BTM) samples were collected in 2007. Antibodies against Nc was found in 2.5 ± 0.4% (95% CI) of the animals and at least one positive animal was found in 37.0 ± 4.7% (95% CI) of the herds. In addition, Nc antibodies were detected in 16.3 ± 2.0% (95% CI) of the tested BTM. Large herds (≥ 200 animals) were less likely to have seropositive animals for Nc. Logistic regression models showed that herds with more than one animal seropositive for Nc had significantly higher odds ratio of abortion incidence (OR: 11.92, 1.18-120.18 95% CI, p=0.036) and tendency of having more stillbirths (OR: 5.52, 0.87-35.02 95% CI, p=0.07). On the other hand one Nc seropostive cow in the herd was associated with lower odds ratio (OR: 0.22, 0.05-0.91 95% CI, p=0.04) of higher calving intervals. Estonian prevalence results reflect observations in the region. No evidence was found of the pathogens were affecting fertility variables through interactions but independently BHV1 and Nc had an impact on the abortion.

Toxoplasma gondii seroprevalence in dairy and beef cattle: Large-scale epidemiological study in Estonia

Toxoplasma gondii is a zoonotic protozoan parasite that thrives in Estonia. In this nationwide cross-sectional study, we tested sera from 3991 cattle, collected from 228 farms in 2012-2013, for anti-T. gondii immunoglobulin G antibodies using a commercial direct agglutination test. Titer of 100 was set as cut-off: samples that tested positive at the dilution 1:100 were defined as positive. The apparent animal-level seroprevalence was 18.62%. At least one seropositive animal was found on 68.86% of the farms, and seropositive cattle were detected in all counties. The seroprevalence appeared to increase with age until five years (60-71 months) of age, but had no obvious pattern in the older animals. Animals of the local Estonian Red breed had higher odds to test seropositive than did animals of the Estonian Holstein breed. Whether the farm focused on dairy or beef cattle was not associated with an animal testing T. gondii seropositive nor with finding at least one T. gondii seropositive animal on the farm. The odds of finding at least one T. gondii seropositive animal on the farm were higher if the herd size was above median (105 in dairy and mixed dairy farms; 35 in beef and mixed beef farms). The results indicate that T. gondii is endemic within the agricultural setting in Estonia and present on the majority of cattle farms.

Intestinal pathogens, diarrhoea and acute phase proteins in naturally infected dairy calves

Abstract In this study, the association between Eimeria spp. related signs and innate immune response in dairy calves was examined. Calves (n =100) aged 15–60 days were clinically examined and faecal samples, blood samples and deep nasopharyngeal swabs obtained. The samples were analysed for intestinal pathogens, acute phase proteins and WBC count, and respiratory tract pathogens, respectively. Diarrhoea was diagnosed in 32.6% (23.3–43.0%, 95% CI) of calves. An association between the pathogenic Eimeria spp. and diarrhoea was detected by multiple correspondence analysis. Eimeria related signs (diarrhoea, presence of pathogenic species and total oocyst count) were combined resulting a four level variable. Calves with weak signs of eimeriosis had decreased haptoglobin concentrations (p =0.02) and increased fibrinogen concentrations (p =0.048) compared to no signs. Increased haptoglobin and fibrinogen concentrations were associated with respiratory tract infection and umbilical infection. Serum amyloid A and WBC counts showed no association with signs of eimeriosis or clinical diagnoses.

Dirofilaria repens Microfilaremia in Three Dogs in Estonia

In Europe, the zoonotic parasite Dirofilaria repens continues to spread northward. We describe three likely autochthonous canine microfilaremic D. repens infections from Estonia, an European Union country located in the Baltic region of northern Europe. The parasite species was confirmed with sequencing. These are new northernmost D. repens findings in Europe and show that the zoonotic parasite has spread farther north. Infection with D. repens should be included in the list of differential diagnoses for human and animal hosts also in northern Europe.