Detection and identification of blood-borne infections in dogs in Nigeria using light microscopy and the polymerase chain reaction

Abstract

Many sick dogs brought to the University of Ibadan Veterinary Teaching Hospital (UIVTH) are infested with ticks and are anemic. Up until recently, light microscopy (LM) has been the only available means used for detection of blood-borne infections. In other parts of the world, PCR-based assays been used as a gold standard for accurate diagnosis of blood-borne infections. In this study, we used LM and broad-spectrum rRNA gene PCR-based assays on 116 blood samples from dogs brought to the UIVTH for detection of the 18S rRNA gene of Babesia and the 16S rRNA genes of Ehrlichia and hemotropic mycoplasmas. The relationship between clinicopathological findings and PCR results was evaluated. Age, sex, presence of ticks, anemia, co-infection status, and fever were also assessed in relation to PCR positivity to determine the risk factors using stepwise logistic regression analyses. Light microscopic examination revealed an overall prevalence of infection of 14.7% (17/116). Organisms detected were Babesia canis (3.5%), Ehrlichia canis (10.3%) and Trypanosoma congolense (0.9%) and a single coinfection with Babesia canis and Ehrlichia canis (0.9%). PCR analysis revealed 89/116 (76.7%) positive samples. Infections with 1, 2 and 3 infectious agents occurred in 49 (55.1%), 36 (40.4%) and 4 (4.5%) samples, respectively. Specifically, among the 89 PCR positive samples, Babesia spp. (85.4%) was the most abundant infection followed by Ehrlichia spp. (46.1%) and hemoplasmas (13.5%). Sequencing of PCR products identified two samples (1.7%) that contained Hepatozoon canis DNA. Sequencing of hemoplasma positive samples identified ‘Candidatus Mycoplasma haemobos’ in 0.8% of dogs. Using PCR, a 5-fold higher prevalence of blood-borne infections was found in the dogs (76.7%, 89/116) than with LM (14.7%, 17/116) alone” Dogs between 1 and 12 months were the most frequently infected with multiple agents (47.2% double and 50.0% triple infections). Male dogs had the highest prevalence of infection (80.4%) and more triple infections (75.0%). A total of 57.3% of infected dogs were anemic. Anemic dogs were 2.77 times more likely to test positive for Ehrlichia spp. (OR: 2.77 95% CI: 1.25–6.16) and dogs with ticks were 3.6 times more likely to test positive for hemoplasmas (OR = 3.60 95% CI: 1.05–12.38). This study underscores the abundance of blood-borne infections in dogs in Ibadan, Nigeria, which is underestimated using light microscopy. This is also the first evidence of existence of ‘Candidatus Mycoplasma haemobos’ in a dog in Nigeria and in Africa. Consequently there is a need for molecular diagnostic facilities for routine screening of sick animals, as multiple infections were not found by light microscopy.

Detection and identification of blood-borne infections in goats in Nigeria using light microscopy and polymerase chain reaction

“…Full blood count, haemoglobin concentration, and total plasma protein were determined from each blood sample using standard haematological techniques [25][26][27] and as previously described by Happi, et al [18].…”

“…Haemoparasitism creates limitation to improved productivity, animal health [13] and economic gain [14][15][16][17] [18][19][20] and these have been attributed to various reasons ranging from the parasite similarity to some cell structures, other parasites, artifacts due to faulty processing of slides, level of parasitaemia, and the competency of the microscopist [19]. On the other hand, Polymerase Chain Reaction (PCR) provides a more accurate diagnosis owing to its higher sensitivity and specifi city, and it is fast becoming an inevitable facility for routine diagnosis given the large repertoire of haemoparasitic diseases with the need for adequate/specifi c therapy.…”

Efectividad de los métodos diagnósticos para la detección de ehrlichiosis monocítica humana y canina

“…Este método diagnóstico se realiza llevando a cabo la tinción de un frotis de sangre periférica que puede ser teñido con Giemsa para buscar mórulas en los monocitos mediante microscopía. La presencia de éstas puede dar indicios de infección por E. chaffeensis o E. canis siendo un diagnóstico rápido y de bajo costo [17][18][19][20] . Este método presenta ciertas desventajas como lo son su baja sensibilidad, atribuido principalmente a la baja bacteriemia, implicando una mayor inversión de tiempo para la búsqueda de mórulas, lo que dificulta su identificación.…”

“…Los resultados obtenidos demostraron que tres muestras fueron positivas mediante evaluación microscópica (1,5%), mientras que por RPC, 47 muestras fueron positivas (22,9%) incluidas en éstas, las tres muestras positivas por microscopía. Por otra parte, Happi y cols., (2018), pudo detectar en 12 muestras (10,3%) la presencia de mórulas, mientras que, por RPC del gen 16S ARNr obtuvo 42 resultados positivos (36,2%) 18 .…”

Molecular detection of Ehrlichia canis and Anaplasma platys in dogs from municipality of Belém, State of Pará, Brazil

“…In addition to these pathogens, the tick can also transmit other pathogenic microorganisms such as Babesia spp. and Hepatozoon canis that cause common mixed infections (CICUTTIN et al, 2015;HAPPI et al, 2018).…”