Seroprevalence Study of Brucellosis in Cattle and Human in Bahirdar Milkshed
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2005-06
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ABSTRACT
A study on cattle tick dynamics was conducted on three agro-ecological zones of Wolayta, Ethiopia, from August 2004 to March 2005 with the objective of identifying the common species, and determining the tick burden difference of indigenous and Holstein cross. The study was conducted using cross-sectional and longitudinal designs to asses the adult ticks attached on cattle during wet and dry periods; and asses the monthly total tick burden on animals in all the three agro-ecological zones respectively. A total of 6191 and 5991 adult ticks were collected from half-body regions of 138 cattle from each agro-ecological zone in wet and dry periods. From these four genera, and eleven species in general identified in all the study areas. The percentages of tick genera identified at highland, midland and lowland in wet and dry periods were Amblyomma (46.44% and 25.11%; 45.87% and 50.47%; 58.94% and 48.93% respectively), Boophilus (46.92% and 73.34%; 47.53% and 47.47%; 30.71% and 45.40% respectively), Rhipicephalus (5.08% and 1.55%; 6.60% and 2.06%; 8.41% and 5.67% respectively) and Hyalomma ( 1.56% and 1.94% at highland and lowland respectively in wet period only). During the wet period Boophilus decoloratus (46.92%), Amblyomma variegatum (20.82%), Amblyomma gemma (12.02%), Amblyomma cohaerens (10.26%), Amblyomma lepidum (3.32%) and Rhipicephalus evertsi evertsi (2.15%) were found to be the six most top common tick species at highland in decreasing order of abundance. While Boophilus decoloratus (47.53%), Amblyomma variegatum (25.95%), Amblyomma gemma (13.63%), Amblyomma cohaerens (4.02%), Rhipicephalus evertsi evertsi (4.37%) and Amblyomma lepidum
(2.27%) were found to be the six most abundant and common tick species at Kokatie, midland, in descending order. Amblyomma variegatum (36.75%), Boophilus decoloratus (30.71%), Amblyomma gemma (17.78%), Rhipicephalus evertsi evertsi (6.14%), Amblyomma cohaerens (2.58%), and Amblyomma lepidum (1.83%) were found to be the six most top common tick species at Bombie, lowland, in decreasing order of abundance. During dry period Boophilus decoloratus (73.35%), Amblyomma gemma (17.87%), Amblyomma variegatum (4.20%), Amblyomma cohaerens (2.16%) and Rhipicephalus evertsi evertsi (1.30%) at highland; Boophilus decoloratus (47.47%), Amblyomma gemma (29.03%), Amblyomma variegatum (10.11%), Amblyomma cohaerens (5.99%), and Amblyomma lepidum (5.34%) at midland; and Boophilus decoloratus (45.40%), Amblyomma gemma (35.12%), Amblyomma variegatum (11.39%), Rhipicephalus evertsi evertsi (3.49%) and Amblyomma lepidum (2.19%) at lowland were found to be the most top tick species at each sites in decreasing order of abundance.
From this study the relative number of Amblyomma variegatum was significantly higher during wet period than dry period at all the three agro-ecological zones (t = 10.2719, P = 0.000 at α = 0.05) . But the relative number of Amblyomma gemma was significantly highest in dry period (t = -7.7583, P = 0.000 at α = 0.05). At all the study areas Amblyomma cohaerens relative distribution was higher significantly in wet (t = 4.3619, P = 0.000 at α = 0.05). The relative number of Boophilus decoloratus was significantly higher during dry period (t = -5.3937, P = 0.0000 at α = 0.05). The sex ratios of all tick species identified during this study periods, both wet and dry, were skewed towards male except for Boophilus decoloratus. The most preferred predilection sites of al
Amblyomma species were scrotum/udder, brisket, inside part of legs and belly in decreasing order of preference. Boophilus decoloratus preferred attachment sites were dewlap, belly, legs and head. Rhipicephalus species primarily attached to anogenital regions, but few on ear area. Significantly higher total tick burden or infestation was found in wet months (August, September and October), and then start to decline till February (F= 185.843, P= 0.000 at α= 0.05). Among the two breeds, indigenous and Holstein cross, it was found that Holstein cross was infested by high total tick populations (F= 370.610, P= 0.000 at α= 0.05).
Based on the finding of this study it can be concluded that among the species of ticks identified Amblyomma variegatum, Amblyomma cohaerens, Amblyomma gemma, Boophilus decoloratus and Rhipicephalus evertsi evertsi were very important. The total tick burden observed in wet period both on indigenous and Holstein cross; in all the study periods on Holstein cross were higher comparatively.
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Agro-ecological zone, Dynamics, Total tick, Half-body regions, indigenous