Ticks (Acari: Ixodidae) infesting dogs in Nigeria: epidemiological and public health implications

Vector-Borne Pathogens in Guard Dogs in Ibadan, Nigeria

Canine vector-borne diseases are of great relevance not only regarding animal welfare but also in relation to the One Health concept. Knowledge concerning the most relevant vector-borne pathogens in dogs is scarce and limited to stray dogs in most western African regions, and there is virtually no information about the situation in kept dogs presenting (regularly) to vets. Therefore, the blood samples of 150 owned guard dogs in the Ibadan area—in the southwest of Nigeria—were collected and analyzed for the DNA of Piroplasmida (Babesia, Hepatozoon, Theileria), Filarioidea (e.g., Dirofilaria immitis, Dirofilaria repens), Anaplasmataceae (e.g., Anaplasma, Ehrlichia), Trypanosomatidae (e.g., Leishmania, Trypanosoma), Rickettsia, Bartonella, Borrelia and hemotropic Mycoplasma using molecular methods. Overall, samples from 18 dogs (12%) tested positive for at least one pathogen. Hepatozoon canis (6%) was the most prevalent blood parasite, followed by Babesia rossi (4%). There was a single positive sample each for Babesia vogeli (0.6%) and Anaplasma platys (0.6%). Moreover, one mixed infection with Trypanosoma brucei/evansi and Trypanosoma congolense kilifi was confirmed (0.67%). Generally, the prevalence of vector-borne pathogens in this sample group of owned dogs in southwest Nigeria was lower than in prior studies from the country and in other parts of Africa in total. This leads to the assumption that, firstly, the exact geographical location has a major influence on the incidence of vector-borne diseases, and, secondly, it seems to make a difference if the dogs are owned and, therefore, regularly checked at a veterinary clinic. This study should raise awareness of the importance of routine health check-ups, tick and mosquito prophylaxis, and a well-managed infectious disease control program to prevent vector-borne diseases in canines.

Molecular characterisation of Rhipicephalus sanguineus sensu lato ticks from domestic dogs in Nigeria

Rhipicephalus sanguineus is the most widely reported tick in the world. Molecular characterisation is important to verify its taxonomic status in the different parts of the world. In this study, we provide information on the molecular characterisation of R. sanguineus tick of dogs collected from Nigeria. Ticks were collected from 62 of 93 sampled dogs. The collected ticks were subjected to morphological identification with the aid of appropriate entomological keys. Deoxyribonucleic acid (DNA) was extracted from the most prevalent tick species (R. sanguineus) and was subjected to further molecular characterisation protocols. The partial mitochondrial 16S rRNA gene sequences (∼300 bp) were obtained from representative specimens. Data were statistically analysed using the chi‐square (χ²) test. Phylogenetic analysis was performed including different lineages of R. sanguineus (sl) from Africa, Asia, Europe and America, and other species belonging to the R. sanguineus ‘tropical lineage’ (R. linnaei) as well as Rhipicephalus turanicus and Ixodes ricinus. Results of this study showed that R. sanguineus was the most abundant ticks of dogs with a prevalence of 61.8% (68/110; 95% CI = 52.5–70.54), followed by Amblyomma variegatum (20.0%) and Haemaphysalis leachi (18.2%). The molecular analysis shows that they are genetically different from the temperate strains but closely related to those from other West African countries. There is a need to establish the vector competence of this common Nigerian dog tick.

Molecular and Biological Characterization of Haemaphysalis Leachi (Acari: Ixodidae) in Nigeria West Africa

Ticks constitute a serious threat to the wellbeing of humans and other animals. The accurate identification of ticks is paramount in epidemiological investigations. Genetic markers have been identified and used to overcome the limitations of phenotypic identification of ticks. In this study, the cytochrome c oxidase 1 (Cox1) gene was amplified and sequenced for the identification of Haemaphysalis leachi, the putative vector of Babesia rossi in Nigeria. Amplification was successful in 34 out of 39 (87 %) ticks collected from dogs in three Nigerian states with sequence homology of 99 % to H. leachi in Genbank (GenBank: MN663156.1). Maximum Likelihood phylogenetic analysis showed significant grouping of H. leachi sequences in independent monophyletic subclade with a bootstrap value of 100 %. Genetic distance analysis of H. leachi identified in this study indicated a very low level of intraspecific diversity (0.016 %) compared to 0.150—0.190 % interspecific distance to other Haemaphysalis species. The number of eggs laid by engorged female ticks maintained in the laboratory ranged from 885 to 2190 and was proportional to the ticks’ initial weight. The mean value of other biological parameters; female engorgement weight, pre-oviposition period, oviposition period, total egg mass, egg size, efficiency rates of female ticks in converting their food reservoir to eggs and incubation period are, 147.5 mg, 7.8 days, 13.2 days, 59.5 mg, 485.5 × 348.7 µm, 41.2 % and 26.2 days, respectively. This study reports the first molecular identification of H. leachi in Nigeria.

Molecular evidence indicts Haemaphysalis leachi (Acari: Ixodidae) as the vector of Babesia rossi in dogs in Nigeria, West Africa

Babesia rossi is the most pathogenic among the large canine babesias and it is the major cause of canine babesisosis in Nigeria. In South Africa it is transmitted by Haemaphysalis elliptica however, its putative vector in Nigeria where Rhipicephalus sanguineus is the most prevalent tick on dogs compared to Haemaphysalis species has not been ascertained. The incongruity between tick distribution and the frequent detection of B. rossi in Nigeria motivated this investigation to identify the local vector(s) of B. rossi. A total of 3805 ticks were collected from 363 naturally infested dogs from different parts of Nigeria. Of these numbers, 758 engorged female ticks; Rh. sanguineus (n = 660) and H. leachi (n = 98) were incubated for oviposition and hatching. After the completion of egg laying, Rh. sanguineus (n = 69) and H. leachi (n = 24) and their resulting progenies were screened for the presence of B. rossi DNA using a nested PCR targeting the 693 bp of the 18S rRNA gene of Babesia spp. Amplification and sequencing of B. rossi DNA was successful in the adults of H. leachi and their resulting egg and larval progenies but not in the adult Rh. sanguineus and progenies. The B. rossi DNA sequences from the H. leachi and their progenies have 99-100 % identity to each other and 98-99 % identical to sequences of B. rossi in GenBank (GenBank: MH143395.1), thus confirming transovarian passage. This evidence confirms for the first time following the reclassification of H. leachi to H. elliptica in South Africa the role of H. leachi in the transmission of B. rossi in dogs in Nigeria.