Molecular detection of concurrent infections of Anaplasma sp Omatjenne, Theileria mutans, Babesia bigemina and Anaplasma marginale in calves and yearlings in a tick endemic Guinea savannah ecosystem in Cameroon

Abstract

Background Ticks infesting animals constitute one of the most important factors limiting profitable livestock production in sub-Saharan Africa and the region is beleaguered by a paucity of data on diseases implicated in high morbidity and mortality in most of its livestock production systems. Methods In a tick endemic Guinea savannah ecosystem, ticks infesting calves and yearlings during their first eighteen months of life were collected weekly and morphologically identified. PCR, Restriction Fragment Length Polymorphism (RFLP) and sequencing were applied on DNA of tick-borne pathogens in animal blood buffy coat to amplify and characterize the 16S rRNA genes of Anaplasma, Ehrlichia and 18S rRNA gene for Babesia spp. Results Of 31 364 adult ticks, nymphs and larvae collected from the 20 experimental animals, 6525 (20.1%), 7399 (23.6%), 990 (3.2%), 16450 (52.4%) were Amblyomma variegatum, Rhipicephalus spp., other genera, and tick larvae respectively. Tick infestation rates during the rainy season for A.variegatum, Rhipicephalus spp. and larvae were 50.3, 12.4 and 28.3, respectively, while in the dry season the proportions were one, 26.2 and 72.8 respectively. A. variegatum had no effect on haematocrit (P > 0.05) but high Rhipicephalus spp. (Boophilus) infestation rates significantly reduced haematocrit (P < 0.01). All animals had mixed infections of haemoparasites. The effect of season on haematocrit was not significant (P > 0.05). The presence of Anaplasma marginale and Anaplasma sp. Omatjenne in the blood significantly reduced haematocrit (p < 0.0001) while Babesia bigemina and Theileria mutans had no effect (P > 0.05). No E. ruminantium was detected. We report for the first time in Cameroon, the detection of Anaplasma sp. Omatjenne and T.mutans infecting all and four of the animals, respectively. Babesia bigemina, and Anaplasma sp.Omatjenne concurrently occurred in all 20 experimental animals, A.marginale in 15 and T.mutans in four. The mean first-time contact periods (in weeks) for B.bigemina, T.mutans, Anaplasma sp.Omatjenne and A.marginale were 15(3–37), 30(9–43), 21(5–55) and 25(7–55) respectively; and they were not significantly different (P > 0.05). Conclusion The absence of clinical cases of the four pathogens detected during the study demonstrates an endemically stable situation in the region for these infections. With no clinical data on A.sp. Omatjenne and T.mutans infections in this area, further insights into their epizootiology should be of interest.