Abstract:
BACKGROUND : Ticks and tick-borne diseases undermine cattle fitness and productivity in the whole of sub-Saharan
Africa, including Nigeria. In this West African country, cattle are challenged by numerous tick species, especially during
the wet season. Consequently, several TBDs are known to be endemic in Nigerian cattle, including anaplasmosis,
babesiosis, cowdriosis and theilerioris (by Theileria mutans and Theileria velifera). To date, all investigations on cattle
TBDs in Nigeria have been based on cytological examinations and/or on serological methods. This study aimed to
ascertain the occurrence of tick-borne pathogens of veterinary and zoonotic importance in cattle in Nigeria using
molecular approaches.
METHODS : In October 2008, 704 whole blood samples were collected from indigenous cattle in the Plateau State,
Nigeria. Analysis for tick-borne pathogens was conducted by means of PCR-based reverse line blotting (RLB) and
sequencing targeting a panel of five genera of microorganisms (i.e. Babesia, Theileria, Anaplasma, Ehrlichia and
Rickettsia spp.).
RESULTS : In total, 561/704 (82.6 %) animals were found infected, with 465 (69.6 %) of them being infected by two
or more microorganisms, with up to 77 possible combinations of pathogens detected. Theileria mutans was the
most prevalent microorganism (66.3 %), followed by Theileria velifera (52.4 %), Theileria taurotragi (39.5 %),
Anaplasma marginale (39.1 %), Anaplasma sp. (Omatjenne) (34.7 %), Babesia bigemina (7.9 %), Anaplasma centrale
(6.3 %), Anaplasma platys (3.9 %), Rickettsia massiliae (3.5 %), Babesia bovis (2.0 %) and Ehrlichia ruminantium
(1.1 %). Calves were found significantly less infected than juvenile and adult cattle.
CONCLUSIONS : This study provides updated, molecular-based information on cattle TBDs in Nigeria. The molecular
approach employed allowed the diagnosis of numerous positive cases including carrier statuses, multiple infections
and novel pathogen detections within the indigenous cattle population. Moreover, the RLB method here described
enabled the detection of veterinary agents not only pertaining to bovine health, including also those of zoonotic
importance.
The high prevalence recorded for T. mutans, T. velifera, A. marginale, T. taurotragi and Anaplasma sp. (Omatjenne),
suggests they may be endemically established in Nigeria, whereas the lower prevalence recorded for other
microorganisms (i.e. A. centrale and B. bovis) highlights a less stable epidemiological scenario, requiring further
investigations.
