Susceptibility of Indigenous Cattle Breeds to Co-Infection with Multiple Tick-Borne Pathogens
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Date
2013-12
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University of Ghana
Abstract
The control of tick-borne diseases in an endemic region is very challenging and costly
due to the presence of multiple pathogens from the seven globally-important livestock
intracellular pathogens. This problem is exacerbated by the availability of competent
vector ticks for each pathogen strain, thus resulting in enhanced transmission efficiency
and higher infection prevalence of disease among cattle from the tropical region than the
temperate region. Unfortunately, these diseases are poorly controlled in sub-Saharan
Africa largely due to lack of understanding of the infection biology of the pathogen
species.
Understanding the species composition of pathogens of infected cattle in Ghana will
allow for the formulation of cost effective interventions that will enable the development
of applicable control strategies and improve the adaptive capacity of tick-borne diseases.
In this thesis, Anaplasma marginale, Babesia bigemina and Theileria species were used
as model bacterial and protozoan blood-feeding pathogens to examine whether genetic
diversity in cattle correlates with quantitative differences in co-infection prevalence
among indigenous breeds of cattle from different Agro-ecological zones in Ghana.
A low-cost molecular approach (multiplex PCR) was developed to assess the multi-
pathogen complex situation in the indigenous cattle of four distinct breeds (Sanga,
Gudali, West African Shorthorn (WASH) and White Fulani).
The overall pathogen co-infection prevalence in indigenous cattle breeds examined was
26.4% (105/397). Out of this total, only six cattle, representing 1.5% (6/397) of the
population were co-infected with all three different tick-borne pathogens - Theileria
species, Anaplasma marginale, and Babesia bigemina. 95 cattle 23.9% (95/397) were co-
infected with Anaplasma marginale and Theileria species, whereas four cattle 1.0%
(4/397) were co-infected with Anaplasma marginale and Babesia bigemina. Surprisingly,
no individual cattle were found to be co-infected with Babesia bigemina and Theileria
species. The overall infection prevalence of cattle was 62.9% (250/397). Significant
(p=0.00) variation was observed in co-infection prevalence between breeds of indigenous
cattle examined. Comparisons of quantitative differences in the number of different
strains among cattle from diverse agro-ecological zones strongly support the significant
(p=0.01) effect of the type of ecological zone on the number of tick-borne pathogens that
circulate in cattle. The data also demonstrated that 145 cattle 36.5% (145/397), harboured
single pathogen species. Out of the total number of single infected cattle, Anaplasma
marginale alone constituted 36.3% (144/397). Only one cattle 0.3% (1/397) was infected
with Theileria species alone. Notably no cattle were infected with Babesia bigemina
pathogen alone at the time of the study. Importantly high progression of the number of
multiple-pathogen infected cattle, over the duration of infection, at both the level of the
individual host and the population was found, suggesting the lack of immunity against co-
infection of cattle in the endemic region.
Description
Thesis (MPHIL)-University of Ghana, 2013