Study on Ogaden Small Ruminant Haemonchosis: Morphological Characterization and Susceptibility to Albendazole and Tetramisole
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Date
2004-06
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Addis Ababauniversity
Abstract
The current study was conducted from August 2003 to March 2004 with an attempt to
determine the prevalence, morphological characteristics and susceptibility of Ogaden isolate
of H. contortus to Albendazole and Tetramisole. During the study period a total of 196
animals (114 sheep and 82 goats) of Ogaden origin were examined. The overall prevalence of
Haemonchus species was 91.23% and 82.93 % in sheep and goats respectively. Where as
37.72% and 40.24% prevalence of Trichostrongylus. axei was recorded in sheep and goats
respectively. Statistically significant difference (p < 0.05) was observed between different
months of the study period for both abomasal parasites. Out of 3187 female Haemonchus
worms recovered from sheep for vulvar morph study, 49.49%linguiform, 28.51% knobbed
and 23% smooth were recorded. Similarly from goats out of 2386 female Haemonchus,
53.83%linguiform, 18.45% knobbed and 27.61% smooth were recorded. Statistically
significant difference (p < 0.05) was observed among the three major vulvar flaps between
different months of the study period in both sheep and goats. A total of 1580 linguiform
female Haemonchus from sheep were further classified and differentiated into 27.16%A,
14.80% B, and 5.34%C and 2.18%I. Similarly from goat a total of 1285 linguiform female
Haemonchus were identified as 27.35 % A, 17.54% B, and 6.63% C and 2.31% I. With in the
linguiform morphotypes, the A type linguiform was noted to exhibit monthly fluctuation (p <
0.05) during the study period. In the current study from a total of 76 sheep a total of 1159
adult male Haemonchus recovered and identified into 95.08% H. contortus, 3.45% H. placei
and 1.47%H. longistipes. Similarly from a total of 55goats, 841 male Haemonchus were
collected and identified as 96.55%H. contortus, 2.97%H. placei and 0.48 %H. longistipes.
With regard to the distribution of mono and/or poly specific Haemonchus species, out of the
76 sheep examined 57.89% were harbouring H. contortus only, 22.37% H. contortus and H.
placei, 7.89% H. longistipes and H. placei and the rest 11.84% were having H. contortus, H.
placei and H. longistipes. As for goats, out of the 55 animals examined, 58.18% were found
to harbour H. contortus mono-species, 38.18% H. contortus and H. placei, 3.64% H.
longistipes and H. placei and unlike sheep none was found to harbour triple Haemonchus
species. This result unveiled the coexistence and sympatry of two or three Haemonchus
species in a single small ruminant host thus requiring the consideration of such heterologous
hosts in the control strategy of the parasite. On the other hand, a total of 30 lambs were used
for efficacy evaluation of Albendazole and Tetramisole in the controlled experimental study.
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The lambs were divided into four treatment groups of five lambs in each group, one positive
and one negative control groups also consisting of five in each group. Exiptol Greece,
Albendazole Pakistan, Tetramsole Greece and Duxamintic Pakistan anthelmintics were
evaluated by FECRT, controlled anthelmintic efficacy test and egg hatch assay test. Epg was
observed to be strong indicator of induced infection in all the infected groups of animals
showing statistically very significant difference (p < 0.05) between pre infection, post
infection, pretreatment and post-treatment during the entire experimental study period. All the
drugs were found to possess a 100% efficacy value up on evaluation by aforementioned
efficacy detection techniques indicating also the susceptibility of Ogaden isolate H. contortus
to all tested drugs irrespective of their origin. In view of the fact where helminthosis
dominated by haemonchosis is confronting animal productivity of the study area, due
attention to the disease and control interventions should be launched to minimize any
economic loses and increase small ruminant productivity. Any control option that needs to be
conducted in the study area should consider the coexistence of two or three species of
Haemonchus spp in single host and involvement of heterologous hosts. The efficacy of the
evaluated anthelmintics can only be maintained and conserved by wise and better utilization
of the existing drugs to prevent the inevitable problem of anthelmintic resistance as the
consequence of anthelmintic usage.
Key words: Sheep, goat, Haemonchus spp, Prevalence, Vulval morphs, Efficacy,
Albendazole, Tetramisole, Ogaden, Ethiopia
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Keywords
Sheep, goat, Haemonchus spp, Prevalence, Vulval morphs, Efficacy, Albendazole, Tetramisole, Ogden, Ethiopia