Abstract:
Ticks and tick-borne diseases (TBDs) cause significant losses, through their effects on health, production of animals and humans worldwide. Notably, the countries located within the tropics and subtropics such as Uganda are the most affected due to abundance and distribution of the tick vector. Unfortunately, there is little data in Karamoja Region regarding tick species and the pathogens they transmit. Therefore, a cross-sectional study was undertaken to determine the various tick species, and to detect the tick-borne pathogens within the ticks collected from cattle in Karamoja Region, northeastern Uganda. Between June 2017 and early September 2017 (wet season), a total of 4,897 ixodid ticks were collected from 100 cattle in 20 purposively-selected herds. Three genera of ticks, namely Amblyomma (96.8%), Hyalomma (0.6%) and Rhipicephalus (2.6%) were identified. From the ticks collected, the most dominant species was A. lepidum (93.85%), followed by A. variegatum (2.0%), R. evertsi evertsi (1.0%) and A. gemma (0.98%). Tick species that have not been reported in recent studies in Uganda were found amongst cattle in Karamoja, and these were R. pravus, R. praetextatus and R. turanicus. A representative number of ticks, from each tick species identified in the present study were placed in pools of 1 to 10. Subsequently, a reverse line blot (RLB) hybridization assay was performed to screen for the presence of tick-borne pathogens. Out of the 40 tick pools, 30 (75%) were positive for tick-borne pathogens of the genera Ehrlichia, Anaplasma, Babesia and Theileria. The RLB assay results showed that 57% (n=17) of the tick pools were positive for single infections, while 43% (n=13) had mixed infections. The most frequently detected tick-borne pathogens were
T. parva (10 pools), T. velifera (10 pools), T. mutans (9 pools) and Theileria sp. (sable) (5 pools). Other pathogens detected were E. ruminantium, B. microti, B. rossi, T. separata and B. bigemina. The tick-borne species B. microti, B. rossi, Theileria sp. (sable) and T. separata are not common in cattle, or not known to infect cattle, but were detected from the ticks collected. The detection of B. microti in this study may point to incidental infections with implications for human health. There could have also been a possibility of cross reactions during the RLB analysis leading to the detection of B. microti in this study. These findings provide knowledge of the distribution of ticks and epidemiology of tick-borne pathogens in cattle and may provide support for control of TBDs and improve cattle productivity.
