Please cite this article in press as: Kazungu, Y.E.M., et al., Incremental effect of natural tick challenge on the infection and treatment method-induced immunity against T. parva in cattle under agro-pastoral systems in Northern Tanzania. Ticks Tick-borne Dis. (2015), http://dx.doi.org/10.1016/j.ttbdis.2015.04.014 ARTICLE IN PRESS G Model TTBDIS-482; No. of Pages 5 Ticks and Tick-borne Diseases xxx (2015) xxx–xxx Contents lists available at ScienceDirect Ticks and Tick-borne Diseases j ourna l h o me page: w ww.elsevier.com/locate/ttbdis Original article Incremental effect of natural tick challenge on the infection and treatment method-induced immunity against T. parva in cattle under agro-pastoral systems in Northern Tanzania Yvette E.M. Kazungu a , Elisa Mwega b , Moses Ole Neselle d , Raphael Sallu e , Sharadhuli I. Kimera c , Paul Gwakisa a,b,∗ a School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania b Permanent address: Genome Sciences Centre, Faculty of Veterinary Medicine, Sokoine University of Agriculture, Morogoro, Tanzania c Department of Veterinary Medicine and Public Health, Faculty of Veterinary Medicine, Sokoine University of Agriculture, Morogoro, Tanzania d Simanjiro Development and Conservation Trust, P.O. Box 7460, Arusha and Southern African Centre for Infectious Disease Surveillance (SACIDS), Sokoine University of Agriculture, Tanzania e Tanzania Veterinary Laboratory Agency (TVLA), P.O. Box 9254, Dar-es-salaam, Tanzania a r t i c l e i n f o Article history: Received 13 September 2014 Received in revised form 28 April 2015 Accepted 29 April 2015 Available online xxx Keywords: Northern Tanzania Maasai ECF vaccination ITM Theileria parva a b s t r a c t This study was conducted to assess the incremental effect of natural tick challenge on the infection and treatment method-induced immunity against T. parva under agro-pastoral systems in Simanjiro district, Northern Tanzania. T. parva specific antibody percent positivity and prevalence of T. parva parasites were studied in relation to duration post vaccination and proximity to Tarangire National park. A total of 381 cattle were included in this study, of which 127 were unvaccinated and 254 had been vaccinated at different time points between 2008 and 2014. Antibody percent positivity (PP) determined by the PIM- based T. parva ELISA and the prevalence of T. parva parasites detected by a nested PCR based on the p104 gene were used to compare vaccinated and unvaccinated cattle. Results showed that seroprevalence was significantly higher in vaccinated than unvaccinated cattle (OR 10.89, p = 0.0341). Only 1.6% (6/381) of all cattle were seronegative and 5/6 of these were unvaccinated. Prevalence of T. parva parasites was significantly higher in vaccinated (50.39%) than unvaccinated (19.69%) cattle (OR 2.03, p = 0.0144). While there was a positive association between PP and duration post vaccination but the latter was inversely associated with T. parva parasite prevalence. This study also showed that cattle which were closer to the park had higher antibody PP and T. parva prevalence. It is concluded that duration post vaccination as well as proximity from the wildlife in Tarangire National park together may exert an incremental effect on the outcome of ECF vaccination by influencing stronger antibody immunity of cattle and ability to withhold high T. parva infection pressure under constant field tick challenge. Further, the high seroprevalence in vaccinated and unvaccinated cattle suggests a likely state of endemic stability to T. parva in the study area. © 2015 Elsevier GmbH. All rights reserved. Introduction Tick-borne diseases constrain the improvement of livestock pro- duction efficiency in 11 countries of eastern, central and southern Africa (Mukhebi et al., 1992). The most important of these diseases is East Coast fever (ECF), which is caused by the protozoan parasite Theileria parva. The disease is the major cause of deaths, especially ∗ Corresponding author at: SUA, P.O. Box 3258, Morogoro, Tanzania. Tel.: +255 78 2437508/23 2603511; fax: +255 23 2604647. E-mail address: psgwakisa@gmail.com (P. Gwakisa). among calves in Maasai pastoralist herds in Northern Tanzania, causing calf mortality of about 40–80% (Homewood et al., 1987, 2006; Di Giulio et al., 2003). The predominant control strategy for ECF is based on the use of acaricides to control the tick vector, Rhipicephalus appendiculatus (Norval et al., 1992). This method is limited by the high cost of acaricides, development of resistance by vector ticks, disruption of endemic stability, food safety concerns and environmental impacts (deCastro, 1997; George et al., 2004; Ministry of Water and Livestock Development, 2004). Immuniza- tion of cattle by the infection and treatment method (ITM) offers a valuable alternative for ECF control (Oura et al., 2004). Immu- nized animals develop an attenuate infection but also a long-lasting http://dx.doi.org/10.1016/j.ttbdis.2015.04.014 1877-959X/© 2015 Elsevier GmbH. All rights reserved.