Study on Concurrent T. Congolense and H. Contortus Experimental Infection in Goats: Interaction and Pathogenic Effects
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Date
2006-06
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Publisher
AAU
Abstract
Study on concurrent Trypanosoma cOllgo/ellse and Haemonchus COllrortliS infections to assess
the interaction and pathogenic effect of single and mixed experimentally induced infection were
conducted in goals. A total of 25 goats of approximately one year old were divided into five
groups and each group was infected either with H. COlltorWs one week after a preceding infection
with T. congo/elise or with primary H. conlOrlus infection one week prior to T. cOllgo/ellse or
infection with either the nematode or trypanosome alone, and the fifth group was served as non
infected control. For experimental purpose each experimental animals were infected with T.
congo/elise. derived from the donor goat after one passage in mice with total intravenous
inoculation of 5x I 4 T. congo/elIse. The tOlal infective dose of H. cOl/torll/S, which was given
orally to each animals was, 10,000 3rd stage larvae. Parasitological observations such as prepatent
period, faecal egg count, woml burden and trypanosome parasitaemia; and hematological
parameters like packed cell volume, haemoglobin concentration. mean corpuscular volume
(MCV), mean corpuscular haemoglobin concentration (MCHC), red blood cell counts, white
blood cell coul1ls. differential leukocyte counts (eosinophil, lymphocyte and neutrophils), total
protein and also clinical parameters including body weight change, mortality rates among various
treatment groups were made in mixed infected groups and in animals singly infected with ei ther
parasites. It was revealed that the order of infection in the preceding or subsequent infection was
very important in which the most hannful combination was a primary T. cOllgo/eflse infection
one week prior to Ii. COllforllls super Infection. that resulted in progressive and sever anaemia
accompanied by leucopenia, hypoprOleinemia, loss of weight and short prepatem period of H.
COlftorlllS. Except animals mono infected with H. COnforms, which have shown macrocytic
hypochromic anaemia, all other treatmem groups have revealed nomlocytic nonnochromic
anaemia throughout the whole observation period. The result also showed that animals with
concurrent T. cOllgo/ellse and Ii. COI/lortus run high risk of succumbing during the infection
period. Higher rate of mortality and more pronounced pathological effects were observed in
combined infections than single ones. It was concluded that the increased I/. cOlllortus egg
excretion observed in animals infected with both parasites might signi fi cantly increase the risk of
nematode infections. The interaction between these two highly potent anaemia causing pathogens
should be considered whenever attempts are made to control these two diseases.
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Keywords
Goat, Concurrent infection, Trypanosoma congo/ense, Haemollchus COlltOrtus, Interactions.