Saulius Petkevičius

The propensity of voles and mice to transmit Borrelia burgdorferi sensu lato infection to feeding ticks

Lyme borreliosis (LB) caused by the spirochete Borrelia burgdorferi sensu lato is the most common tick-borne zoonosis in the Northern Hemisphere. B. burgdorferi s.l. can infect humans and wild and domestic animals. Ixodes ricinus is the main vector, and small rodents are the most important mammalian reservoirs hosts of B. burgdorferi s.l. in Europe. The prevalence of B. burgdorferi s.l. in I. ricinus ticks from captured rodents, calculated specific infectivities, and transmission coefficients were estimated in order to investigate the role of voles and mice in transmission of the LB causative agent. A total of 12.3% (53 out of 431) of immature I. ricinus ticks from rodents in Lithuania and 3.25% (21 out of 646) in Norway were infected with B. burgdorferi s.l. In Lithuania a total of 40% infested Microtus arvalis, 29% of Myodes glareolus and 4.8% of Apodemus flavicollis carried infected larvae and 67% of M. glareolus, 36% of M. arvalis but none of A. flavicollis carried infected nymphs. In Norway, 2.4% of larvae and 12.1% of nymphs feeding on A. flavicollis were infected. A total of 9% of infested A. flavicollis carried infected larvae and 13% - infected nymphs. Borrelia afzelii was the single genospecies identified in ticks feeding on rodents in Lithuania, and was predominant in ticks collected from rodents in Norway. According to calculated indices of specific infectivity and tick-to host transmission coefficient, M. arvalis and M. glareolus voles were found to be more efficient in transmitting B. burgdorferi s.l. to ticks than A. flavicollis mice. GLMM analysis showed that rodent species significantly influenced the probability of a larva being infected with B. burgdorferi s.l. The larvae feeding on M. arvalis and M. glareolus were more likely to be infected with B. burgdorferi s.l. than those feeding on A. flavicollis. This is the first study to report the quantitative roles of voles and mice in the transmission of B. burgdorferi s.l. to larval ticks in Lithuania and Norway.

Detection and molecular characterization of canine babesiosis causative agent Babesia canis in the naturally infected dog in Lithuania

Canine babesiosis caused by Babesia canis is an emerging infectious disease in Europe. Although previously uncommon, canine babesiosis has become quite frequent in Lithuania during the past decade. In the last few years an increasing number of cases with a wide variety of clinical signs have been recorded throughout the country. In Lithuania the identification of the disease agent in veterinarian clinics is based on a microscopic analysis of size and morphology. To date, no data on the genetic characterization of Babesia species in dogs have been documented for Lithuania. A total of 123 blood samples from dogs showing clinical signs of babesiosis on the basis of veterinary examination were tested for the presence of babesial parasites. Babesia isolated from dogs were detected and characterized by nested-PCR and sequence analysis of a fragment of the 18S rRNA gene. Babesia parasites were detected in blood smears of 94 dogs (76.4%). The molecular analysis revealed the presence of B. canis in 108 dogs (87.8%). Two genotypes of B. canis were distinguished on the basis on two nucleotide (GA → AG) substitutions observed in 18S rRNA gene sequences. The results of the present study provide knowledge of the distribution of B. canis genotypes in dogs in Lithuania, and show the necessity to use a molecular analysis for an accurate diagnosis of canine babesiosis.

The impact of grazing management on seasonal activity of gastrointestinal parasites in goats

SummaryThe aim of this study was to examine the impact of grazing management and other risk factors (age, treatment practices) on seasonal activity of gastrointestinal (GI) parasites in goats. Goat flocks naturally infected with GI parasites reared on four Lithuanian farms representing different management regimes were examined during the grazing season in 2011/2012. On three farms the adult goats were grazed in different ways on open pastures (with or without supplementary feeding) or tethered. On one farm all animals were kept indoor (zero-grazing). On each farm, samples were collected at monthly intervals from 13–15 adult and 10 kids. The results showed that grazing of adult goats with feed supplementation or kept indoor, shed the lowest number of strongyle eggs when compared to those kept on pasture (P < 0.05). Delayed turnout and zero-grazing significantly reduced excretion of strongyle eggs but increased the output of oocysts when compared to those grazed on set-stocked pasture together with adult goats. The most prevalent genus on all farms and in both age groups of goats were Teladorsagia spp. This study demonstrates that goats are infected with mixed species of parasites, but proportions of these parasites differed in different grazing management systems. The grazing management, age and season were all major factors that had an impact on GI parasite infection.

Worm-control practices and prevalence of anthelmintic resistance using in vivo FECRTs on smallholder sheep farms in Lithuania

Summary This study determined the prevalence of anthelmintic resistance (AR) in parasitic nematodes on smallholder sheep farms in Lithuania from April to November 2014. Faecal samples were collected from two groups of 10-15 sheep treated with fenbendazole (FBZ) or ivermectin (IVM) on 18 sheep farms. Two samples were collected from each group: on day zero (T1) and 10-14 days after treatment. Faecal egg counts (eggs per gramme, EPG) were determined using a modified McMaster technique. Animals with < 140 EPG on day zero were removed from the analysis. The prevalence of AR was estimated using the in vivo faecal egg count reduction test. AR to FBZ was detected on three of 15 farms where FBZ was used (20 %) and was suspected on one farm (6.7 %). AR to IVM was detected on two of 16 farms where IVM was used (12.5 %). The main species of resistant gastrointestinal nematodes (GINs) identified after treatment were Teladorsagia spp. and Trichostrongylus spp. A questionnaire surveying 71 sheep farmers estimated that 71.8 % of sheep farmers used anthelmintics against GINs. IVM was the most frequently (68.6 %) applied anthelmintic, and 62.7 % of the respondents reported treating their animals twice a year. This study confirmed the presence of AR to GIN infections on sheep farms in Lithuania. Future studies should assess the prevalence of AR to GIN infection using in vitro methods.

Comparative evaluation of efficiency of traditional McMaster chamber and newly designed chamber for the enumeration of nematode eggs

The objective of this study was to perform the comparative evaluation of efficiency of traditional McMaster chamber and the newly designed chamber for the enumeration of nematode eggs in different agriculture animals. Thirteen pig, two horse and two sheep farms were randomly selected, and 815 of pig faecal samples, 264 of horse and 264 of sheep faecal samples were examined. The positive samples were identified by Henriksen and Aagaard (1976) [1] modification of McMaster method. Furthermore, experimental horse faeces were examined by [1] and Urquhart et al., 1996) [2] modifications, whereas pig and sheep faeces were examined by [1] and Kassai, 1999 [3] modifications, respectively. All samples were evaluated in two replicates: using traditional McMaster 0.3 ml chamber – I and newly designed 1.5 ml chamber – II [4]. In pig farms, 11.5% and 18.2% (chambers I and II, P<0.05) of pigs were found infected with Ascaris suum. Furthermore, 14.6% and 17.8% (chambers I and II, P<0.05) of pigs were found infected with Oesophagostomum dentatum and 3.7% and 8.2% (chambers I and II, P<0.05) with Trichuris suis, respectively. In horse farms, 65.5% and 83.7% horses infected with strongyles were identified (chambers I and II, P<0.05. In sheep farms, the number animals of positive to strongyle infection was 81.4% and 96.2% (I and II chambers, P<0.05). The new modification of chamber [4] demonstrated statistically higher sensitivity for enumeration of nematode eggs and for evaluation of farms with infected animals compared to McMaster modifications described in [1-3].

Stable isotope ratio method for the characterisation of the poultry house environment.

ABSTRACT Stable isotope analysis was applied to describe the poultry house environment. The poultry house indoor environment was selected for this study due to the relevant health problems in animals and their caretakers. Air quality parameters including temperature, relative humidity, airflow rate, NH3, CO2 and total suspended particles, as well as mean levels of total airborne bacteria and fungi count, were measured. Carbon isotope ratios (13C/12C) were obtained in size-segregated aerosol particles. The carbon (13C/12C) and nitrogen (15N/14N) isotope ratios were measured in feed, litter, scrapings from the ventilation system, feathers and eggs. Additionally, the distribution of δ13C and δ15N values in different tissues of the chicken was examined. The airborne bacteria and fungi extracted from the air filters collected from poultry farms were grown in the laboratory in media with known isotope values and measured for stable isotope ratios. Analysis of isotope fractionation between microorganisms and their media indicated the applicability of stable isotope analysis in bulk samples for the identification of source material. The analysed examples imply that stable isotope analysis can be used to examine the indoor environment along with its biology and ecology, and serve as an informative bioanalytical tool.