Diversity and Geographic Distribution of Dog Tick Species in Sri Lanka and the Life Cycle of Brown Dog Tick, Rhipicephalus sanguineus Under Laboratory Conditions

Comprehensive study of ticks and tick-borne diseases in dogs in Nepal: molecular identification, risk analysis and hematological alterations

BACKGROUND

Ticks are responsible for the transmission of various viral, bacterial, and protozoal pathogens through their mouthparts while feeding on the blood of the host. Owing to the increasing trend of tick-borne diseases, they are considered major emerging public health issues throughout the globe. In South Asia, the major important canine tick-borne pathogens are Babesia spp., Hepatozoon canis, Ehrlichia canis, Anaplasma platys, and Borrelia burgdorferi. Among various diagnostic tests, molecular techniques are considered the gold standard for the detection of tick-borne diseases. A total of 341 canine blood samples were collected from Kathmandu, Pokhara, and Chitwan, Nepal. The collected blood samples were subjected to hematological analysis, DNA extraction, and conventional polymerase chain reaction to detect the presence of tick-borne pathogens. Additionally, a total of 219 ticks were collected from the sampled dogs and identified via morphometry.

RESULTS

PCR assays revealed four tick-borne pathogens, Babesia spp., Ehrlichia canis, Hepatozoon canis, and Anaplasma platys, with prevalence rates of 26.09%, 5.87%, 3.52%, and 2.93%, respectively, and an overall prevalence of 31.09% (95% CI: 26.27-36.34%). However, this study could not identify the prevalence of Borrelia burgdorferi. During the hematological analysis, anemia and thrombocytopenia in the sampled dogs were significantly associated with the presence of Babesia spp. (p < 0.01 and p < 0.05, respectively), lymphocytosis was significantly associated with Hepatozoon canis (p < 0.001), and thrombocytopenia was significantly associated with Ehrlichia canis (p < 0.05). Among the ticks infesting dogs at the study sites, the Rhipicephalus genus was the most prevalent, followed by Haemaphysalis and Dermacentor, with an overall tick infestation rate of 27.86%. Geographic location, type of dog (stray or pet), and body condition score were determined as potential risk factors by multiple logistic regression analysis (OR = 0.40, 2.16, 0.73; p < 0.01, p < 0.05, p < 0.05, respectively) for the presence of canine tick-borne pathogens.

CONCLUSIONS

This study identified at least four species of canine tick-borne pathogens and three genera in dogs from study area. Findings of this study highlights the importance of robust treatment, control and preventive measures to mitigate the transmission of these pathogens.

First report of highly pathogenic Theileria luwenshuni in Sri Lanka: Are Jaffna sheep resistant to theileriosis?

Theileriosis is a tick-borne piroplasmid infection that affects small ruminant production, resulting in significant economic losses. This study investigated theileriosis and its potential vectors in the Jaffna sheep breed in Sri Lanka. Blood (n = 100) and ticks (n = 57) were randomly collected from three farms. Management practices and other demographic data were collected using a questionnaire. Giemsa-stained blood smears facilitated microscopic analysis of piroplasms. The prevalence of theileriosis was compared between farms, age, and gender categories using a Chi-square test or a Fisher's exact test. The molecular identification was achieved using a nested PCR targeting the 18S rRNA gene of Theileria spp. Subsequently, PCR amplicons were subjected to bidirectional sequencing and phylogenetic analysis. Microscopic examination and nested PCR revealed 38.0 % and 90.9 % prevalence of Theileria species, respectively, with a significant difference (p = 0.0015). The phylogenetic analysis showed that the Theileria spp. identified is the highly virulent Theileria luwenshuni. Collected tick species were: Haemaphysalis bipsinosa, Haemaphysalis intermedia, Rhipicephalus haemaphysaloides, Rhipicephalus linneai and Hyalomma marginatum isaaci; the most prevalent being H. bispinosa (68.4 %). This is the first report and molecular characterisation of T. luwenshuni in Sri Lanka, a highly pathogenic species recorded in small ruminants in tropical and subtropical countries but does not cause clinical signs in the Jaffna sheep breed. Findings of the current study suggest that Jaffna sheep tolerate the infection by T. luwenshuni. However, them being carriers poses a major risk to immunocompromised farm animals, especially the exotic sheep and goat breeds in the country.

Establishment of Pathogen-Free Rhipicephalus bursa Colonies Under Laboratory Conditions for the Vector Competence Studies

Rhipicephalus bursa, the primary vector of Babesia ovis, is also considered to transmit Theileria, Babesia, and Anaplasma spp. These claims are based on pathogen detections rather than experimental validation. To confirm vector competence, sterile ticks must acquire pathogens from infected hosts and transmit them to other hosts. The basic step is establishing a pathogen-free tick colony. In this study, engorged R. bursa females were collected from 12 infested livestock and allowed to lay eggs. The carcasses and larvae were screened for tick-borne pathogens using nPCR. The 0.150 g pathogen-free F1 larvae were fed on New Zealand rabbits, resulting in 592 engorged nymphs that molted into F1 adults. Eighty F1 adults were fed on pathogen-free splenectomized sheep, producing the next larval generation (F2). This protocol was repeated to produce F3 larvae. At the end of all developmental stages, ticks were screened via nPCR and found to be negative for tick-borne pathogens. The sheep were monitored for 63 days with no clinical signs or positive nPCR results, confirming F3 larvae as pathogen-free and suitable for vector competence studies. The R. bursa life cycle was completed in 72-153 days, providing a reliable model for vector competence research and offering valuable insights into its biological parameters.

Canine vector-borne infections of working dogs of the Sri Lanka Air Force, and free roaming, and privately owned dogs

Canine vector-borne infections (CVBIs) are a global health problem. The military working dogs of Sri Lanka die at an early age, and CVBIs have been a leading speculated cause. We examined CVBIs in the working dogs of the Sri Lanka air force (SLAF) and free-roaming dogs (FRDs) and privately owned dogs (PODs) country-wide. Giemsa-stained smears were prepared and conventional PCR-positive DNA was subjected to sequencing and phylogeny. Of the 668 dogs sampled, 212 (31.7%) had one or more CVBIs. The prevalence of infections among the FRDs (40.0%) was significantly higher than SLAF working dogs (30.0%; χ2 = 10.5216; p = 0.0012) and PODs (26.2%; χ2 = 5.3414, p = 0.0208) but not between SLAF dogs and PODs (χ2 = 1.7655, p = 0.1838). Many infected dogs were asymptomatic (57.4%), which was higher among the FRDs. Seven infectious agents were identified: Babesia gibsoni, B. canis, Ehrlichia canis, Anaplasma platys, Leishmania sp., Hepatozoon canis, and filaria worms. The most common infection was B. gibsoni (13.8%), followed by E. canis (9.9%). Three tick species: Rhipicephalus linneai, Rhipicephalus haemaphysaloides and Haemophysalis bispinosa were found infesting the dogs. The SLAF dogs were thoroughly quarantined upon arrival, but the infection prevalence was similar to PODs.

Essential oil pharmaceuticals for killing ectoparasites on dogs

BACKGROUND

External parasites, particularly ticks and fleas, are among the most common problems affecting dogs. Chemical medicines are commonly used to prevent and eliminate such external parasites, but their improper use can cause adverse reactions, and the toxins they contain may remain in the environment.

OBJECTIVES

The objective of this study was to investigate the in vitro efficacy of Zanthoxylum limonella, citronella, clove, peppermint, and ginger essential oils against dog ticks and fleas and to test the sensitivity of dogs' skin to these essential oils.

METHODS

The five essential oils were tested for in vitro efficacy against ticks and fleas, and the two most effective essential oils were then tested on the dogs' skin.

RESULTS

The results revealed that these five essential oils at 16% concentrations effectively inhibited the spawning of female engorged ticks. In addition, all five essential oils had a strong ability to kill tick larvae at concentrations of 2% upward. Furthermore, 4% concentrations of the five essential oils quickly eliminated fleas, especially clove oil, which killed 100% of fleas within 1 h. A 50%, 90%, and 99% lethal concentration (LC50, LC90, and LC99) for the essential oils on tick larvae in 24 h were found to be low values. LC50, LC90, and LC99 for the essential oils on flea in 1 h was lowest values. Clove oil at 16% concentration was the most satisfactory essential oil for application on dogs' skin, with a low percentage of adverse effects.

CONCLUSIONS

This study confirmed the effectiveness of essential oils for practical use as tick and flea repellents and eliminators. Essential-oil-based pharmaceutical can replace chemical pesticides and provide benefits for both consumers and the environment.

Molecular characterization of Amblyomma geoemydae using CO1 mitochondrial gene to validate phenotypic taxonomical evaluation

Animal ectoparasites are linked to the spread of serious medical and veterinary important pathogens. Our research intends to close the knowledge gap concerning the numerous ectoparasites that inhabit animals in Wayanad. Ectoparasites in animals brought to the veterinary dispensaries in Wayanad were retrieved and identified morphologically and molecularly. Using a high-quality stereomicroscope, the taxonomic features of the four following species were examined and identified: Haemaphysalis bispinosa, Rhipicephalus annulatus, R. microplus, and Amblyomma geoemydae. The important disease vector A. geoemydae was reported for the first time in Kerala. The important phenotypic characters of the highlighted species A. geoemydae are the edge of the basis capituli is circular without cornua, and the hypostomal dental formula is 2/2. The taxonomically identified four species were subjected to CO1 gene sequence analysis. The evolutionary relationship was inspected through the neighbour-joining method, and the phylogenetic tree was built through the Maximum Likelihood method. The present study has also estimated the diversity index of R. microplus, R. annulatus, H. bispinosa, and A. geoemydae. Among them, R. microplus 0.36638 have reported with the maximum diversity index score. The significance of the study is the presence of Lyme disease vector A. geoemydae, in the Wayanad District of Kerala, and it is the first report of the species from where an outbreak of Lyme disease occurred in 2013.