Parasitological, serological, and molecular survey of trypanosomosis (Surra) in camels slaughtered in northwestern Nigeria.

Surra is a parasitic disease caused by Trypanosoma evansi and transmitted non-cyclically by biting flies. The disease significantly affects the health, productivity, and market value of camels thereby constituting a major constraint to food safety, security, and economy. This is the first study on the prevalence of surra in northwestern Nigeria, using a range of diagnostic tests along the parasitological-serological-molecular continuum hence, emphasizing it as a major enzootic risk for camels in Nigeria. In this cross-sectional study, 600 blood samples were collected from camels at major abattoirs in northwestern Nigeria and evaluated for the prevalence of T. evansi using parasitological (Giemsa staining), serological (CATT/T. evansi), and molecular (VSG-PCR and sequencing) methods. The overall prevalence of surra recorded in this study was 5.3%, 11.5%, and 22.5% using Giemsa-stained blood smears, CATT/T. evansi, and VSG-PCR respectively. However, higher prevalence rates at 6.0%, 13.7%, and 26.7% by Giemsa-stained blood smears, CATT/T. evansi, and VSG-PCR were recorded in Katsina State compared with results from Kano State. A significantly (p < 0.05) higher prevalence by VSG-PCR was observed when compared with both parasitological and serological methods used. Although age and body condition scores were associated (p < 0.05) with surra prevalence in sampled camels, no seasonal association (p > 0.05) was recorded. Sequencing of the VSG region of Trypanosoma spp. Further confirmed the presence of T. evansi as the aetiological agent of surra from the sampled camels. Findings from this study call for the implementation of adequate control measures aimed at reducing the impact of T. evansi infections on camel production in Nigeria.