Detection and molecular characterisation of Ehrlichia canis in naturally infected dogs in South West Nigeria

Tick-Borne Diseases of Humans and Animals in West Africa

Ticks are a significant group of arthropod vectors that transmit a large variety of pathogens responsible for human and animal diseases worldwide. Ticks are the second biggest transmitters of vector-borne diseases, behind mosquitoes. However, in West Africa, there is often only limited knowledge of tick-borne diseases. With the scarcity of appropriate diagnostic services, the prevalence of tick-borne diseases is generally underestimated in humans. In this review, we provide an update on tick-borne pathogens reported in people, animals and ticks in West Africa by microscopic, immunological and molecular methods. A systematic search was conducted in PubMed and Google Scholar. The selection criteria included all studies conducted in West Africa reporting the presence of Rickettsia, Borrelia, Anaplasma, Ehrlichia, Bartonella, Coxiella burnetii, Theileria, Babesia, Hepatozoon and Crimean-Congo haemorrhagic fever viruses in humans, animals or ticks. Our intention is to raise awareness of tick-borne diseases amongst human and animal health workers in West Africa, and also physicians working with tourists who have travelled to the region.

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.

Detection of Ehrlichia spp. in ticks collected from stray dogs in Central and Southeastern Iran

Ehrlichia is an etiologic agent of ehrlichiosis in humans and some animals. Rhipicephalus sanguineus is the main vector of the Ehrlichia canis and dogs, red foxes and yellow jackals are reservoirs of the bacterium. This tick has a worldwide distribution and is regarded as one of the commonest species of ticks in Iran. This research aimed to detect Ehrlichia spp. in R. sanguineus isolated from stray dogs in Central and Southeast Iran (Isfahan and Zabol), by using polymerase chain reaction (PCR) and to evaluate the prevalence of the microorganism in these two areas. Tick samples were collected from stray dogs in Isfahan and Zabol between April and June of 2018. The DNA extraction was performed with commercial kits. PCR was done to determine the 336 bp fragment related to Ehrlichia spp. Overall, 15.21% of pools in both areas were positive for Ehrlichia, 21.42% and 10% of pools were from Isfahan and Zabol respectively. The results confirmed the presence of Ehrlichia spp. in R. sanguineus in stray dogs revealing that dogs and their ticks may have a significant role in the epidemiology of the disease.

Molecular detection and risk factors for Anaplasma platys infection in dogs from Egypt

Background

Anaplasma platys is a tick-borne bacterium which infects blood platelets of dogs, causing canine cyclic thrombocytopenia. The disease is distributed worldwide, particularly in the tropics and subtropics, but information on the epidemiology of A. platys infection in dogs is fragmentary in many countries, including Egypt. In this study, we investigated the prevalence and risk factors associated with A. platys infection in dogs from Egypt.

Methods

A conventional PCR targeting a fragment of the 16S rRNA gene of A. platys was used to screen 500 dogs from five North Egyptian governorates. DNA sequencing and phylogenetic analysis were performed for one of the positive samples.

Results

The overall prevalence of A. platys in the studied dogs was 6.4%. Females of the German shepherd breed without veterinary care had higher odds for A. platys positivity. High tick infestation and lack of anti-tick treatment were also identified as risk factors for A. platys infection. Phylogenetic analysis revealed that the sequence obtained herein was closely related to sequences from Egypt, South Africa and Uruguay.

Conclusions

This is the first large-scale epidemiological study of A. platys in Egypt, where female German shepherd dogs without veterinary care, as well as dogs with high tick infestation and without anti-tick treatment are at a higher risk of infection.

Graphical abstract

Molecular detection and genetic variability of Ehrlichia canis in pet dogs in Xinjiang, China

Background and Aim

As a tick-borne zoonotic pathogen, Ehrlichia canis has already posed a threat to public health and safety. This study aimed to clarify the prevalence and molecular characteristics of E. canis in pet dogs in Xinjiang, China.

Materials and Methods

A total of 297 blood samples of pet dogs and 709 skin ticks (Rhipicephalus sanguineus sensu lato) were subjected to molecular detection using PCR for E. canis 16S rRNA gene, and then, positive samples were amplified, sequenced, and phylogenetically analyzed for E. canis gp36 gene.

Results

The PCR detection showed that the positive rate of PCR was 12.12% (36/297) in blood samples and 15.23% (108/709) in tick samples, respectively. Based on the phylogenetic analysis of E. canis gp36 protein, these E. canis strains in different geographical regions of the world can be divided into Genogroup I and Genogroup II. Among them, the Xinjiang epidemic strain XJ-6 and 533, 36, 1055, Kasur1, and Jake strains were clustered into subgroup 1.1 of Genogroup I, while the XJ-2, XJ-21, and XJ-35 strains and the TWN1, TWN4, CM180, and CM196 strains were closely related and belonged to subgroup 2.2 of Genogroup II, displaying high genetic diversity.

Conclusion

This is the first study focusing on the molecular epidemiology of E. canis infection in pet dogs, which revealed that E. canis infection had been occurred in Xinjiang, China. More importantly, this study confirmed that the substantial variability in immunoreactive protein gp36 from E. canis strains circulating in pet dogs.

Molecular detection and characterization of Anaplasma platys and Ehrlichia canis in dogs from northern Colombia

Ehrlichia canis and Anaplasma platys are intracellular tick-transmitted bacteria that infect dogs; there is evidence for limited zoonotic potential as well. The prevalence of E. canis in Colombia has been evaluated in different regions; however little is known about the prevalence or distribution of A. platys. Neither pathogen has been studied in the Magdalena region, thus the purpose of our study was to assess the prevalence of these pathogens in dogs attending veterinary clinics from the cities of Santa Marta and Ciénaga, and to assess possible associated risk factors for infection. A. platys and E. canis infections in blood were evaluated by Taqman PCR assays. E. canis was detected in 26/170 (15.3%, 95% CI 10.4%-21.8%) and A. platys in 34/168 (20.2%, 95% CI 14.6%-27.3%) of all dogs tested. Eleven dogs (6.5%, 95% CI 3.4-11.7%) were coinfected with both pathogens. Sequencing results showed low diversity within E. canis and within A. platys strains, however a strain of E. canis detected in our study area is genetically distinct from strains reported in another city of Colombia. Our results suggest that for A. platys, Santa Marta dogs were at greater risk than Ciénaga dogs, and that purebred dogs were at slightly lower risk in both areas. The confirmation of these pathogens in northern Colombia should cause concern for the possible co-transmission of these agents to humans or animals in the region.

Molecular evidence of Ehrlichia canis and Anaplasma platys and the association of infections with hematological responses in naturally infected dogs in Kalasin, Thailand

Background

Tick-borne bacteria, Anaplasma platys and Ehrlichia canis are well recognized as the etiology of anemia and thrombocytopenia in dogs. The clinical signs of anaplasmosis and ehrlichiosis range from asymptomatic to severe symptoms . There are insufficient studies about epidemiological surveys of these blood parasites, also the association of infections with the hematological study.

Aim

This study aimed to screen A. platys and E. canis in naturally infected dogs and the effects of the infection on the levels of packed cell volume (PCV) and platelet count.

Materials and Methods

A total of 68 blood samples were collected from free-roaming dogs at Nong Kung Sri district, Kalasin Province, Thailand, and examined for A. platys and E. canis infection by polymerase chain reaction (PCR) and measured PCV levels and platelet count.

Results

Using nested PCR, 42.65% of dogs were infected with one or two pathogens. The molecular detection of anaplasmosis and ehrlichiosis in this population was 29.4% (95% confidence interval [CI]: 18.98-41.71) and 25% (95% CI: 14.4-35.3), respectively. Coinfection occurred at 11.8% (95% CI: 5.22-21.87). Infection with E. canis and coinfection showed significant association with PCV levels (p<0.05) while A. platys infection showed no statistical relationship. Infection with A. platys, E. canis, and coinfection had a non-significant correlation with platelet count (p>0.05).

Conclusion

This study provides data of anaplasmosis and ehrlichiosis in free-roaming dogs which indicated that these zoonotic diseases are widespread and require for disease frequency determination, especially in Kalasin Province of Thailand where data of tick-borne infections in dogs have not been reported.