Distribution and abundance of ticks on cattle and associated tick-borne pathogens from Kilombero and Iringa districts in Tanzania
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Date
2023
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Publisher
Sokoine University of Agriculture
Abstract
Ticks are a major group of arthropod vectors that transmit pathogens that cause devastating
diseases in humans and animals. The information on tick infestation and related tick-borne
pathogens in Tanzania is insufficient. Therefore, this study was conducted to determine
tick prevalence and degree of infestation on cattle as well as associated tick-borne
pathogens, in Kilombero and Iringa districts of Tanzania. A repeated cross-sectional study
was conducted to collect ticks on cattle in wet and dry seasons from January to August
2021. Out of 740 cattle examined, 304 were infested with ticks. In total 1,780 ticks were
counted on one side of the animal’s body and doubled, whereby a total of 3,560 ticks were
recorded. A total of 1,889 tick were collected from the infected cattle including 109 more
tick observed while collecting ticks based on the animal’s posture when restrained on
ground. Thereafter, ticks were identified morphologically using published morphological
keys under a stereomicroscope and confirmed using polymerase chain reaction (PCR) and
sequencing of the mitochondrial CO1 and 16S rRNA genes. The tick-borne pathogens
were detected using PCR. Fisher’s exact test was performed to detect the difference
between the proportion of hard tick species and the study areas and season. One-way
ANOVA was performed to compare mean tick burden between variables (including cattle
age groups, body condition score and frequency of tick control). Out of 1,889 ticks, 1,377
fit in the genus Rhipicephalus, 459 in the genus Amblyomma and 53 in the genus
Hyalomma. The most prevalent tick species identified were Rhipicephalus microplus
(48.1%), Rhipicephalus evertsi (16.4%), and Amblyomma lepidum (16.4%). The
sequencing results of the mitochondrial DNA fragments indicated high nucleotide identity
(96-100%) with sequences in GenBank and Barcode of Life Database (BOLD)
(OM974109-OM974112 and OM978262-OM978265). Seasonality results indicate no
statistically significant difference in the prevalence of tick infestation on cattle during the
dry (41.05%) and wet (41.11%) seasons. The DNA of Anaplasma spp. and
Theileria/Babesia spp. were detected in (70.33%, n=64) of all tick pools. The detection
rate of both Anaplasma and Theileria/Babesia spp. was high in Amblyomma lepidum
(25.00%, n=16) followed by Rhipicephalus evertsi (23.44%, n=15) tick pools. The results
showed high tick prevalence and abundance on cattle suggesting increased risk of tick-
borne disease transmissions and reduced animal production and productivity. Therefore,
tick infestation in the study areas highlight the need for strategic tick control approaches.
Description
Masters Dissertations
Keywords
ticks, cattle, Iringa districts, animals, tick-borne