Seasonal prevalence of ticks and tick-transmitted haemoparasites in traditionally managed N'Dama cattle with reference to strategic tick control in the Gambia.

A survey of tick spatial and seasonal distribution in traditional managed N'Dama cattle over 1 year old was carried out in The Gambia over 16 months. Presence of Anaplasma marginale and Babesia spp. in the blood smears and their antibodies in the serum of same animals were also examined. Tick species, in decreasing order of abundance, were: Boophilus geigy, Rhipicephalus senegalensis, B.decoloratus, Hyalaomma truncatum, H.marginatum rufipes and Amblyomma variegatum. All tick species peaked during the rainy season. Additional B.geigy peaks occurred towards the end of the dry season. The most infested animal body areas were anogenital, udder and abdomen. A.variegatum, Hyalomma spp. and, to a lesser extent, Boophilus spp. showed strong preferences for these anatomical regions. Overall prevalence of A.marginale, B.bigemina and B.bovis haemoparasites were 3.2%, 0.9% and 0.1%, respectively. Peaks of A.marginale and B.bigemina occurred at the end of the rainy season-beginning of the dry season; an additional A.marginale peak was observed at mid-end dry season. Overall antibody seroprevalence were 29.6% for A.marginale, 44.7% for B.bigemina and 5.2% for B.bovis; monthly fluctuations in percentage of seroreactors were limited. Endemic stability for A.marginale and B.bigemina is postulated. Implications of the outcomes are discussed in relation to tick-control strategy in The Gambia.