dc.contributor.author | Gatongi, PM | |
dc.date.accessioned | 2013-05-30T07:16:21Z | |
dc.date.available | 2013-05-30T07:16:21Z | |
dc.date.issued | 1995 | |
dc.identifier.citation | Doctor of Philosophy | en |
dc.identifier.uri | http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/27371 | |
dc.description.abstract | A study on the epidemiological dynamics of gastrointestinal
nematodes of small ruminants was conducted in a semi-arid area of Kenya
over a period of two years. Three major trichostrongylid species were
identified; Haemonchus, Trichostrongylus and Oesophagostomum. Trichuris
and Strongyloides species were occasionally encountered. Of the major
trichostrongylids, Haemonchus gm. was the most prevalent (90%) and
accounted for about 80% of the total worm burden. This species was found to
undergo hypobiosis at levels that varied with seasons: nil levels of hypobiosis
were recorded during the wet months and as much as 80% was recorded
during the dry months. Hypobiosis was not investigated in the other nematode
species. Evaluation of the relationship between the faecal egg count and the
worm burden showed that the two parameters were more highly correlated
during the wet months than during the dry months. This was a desirable
situation because it is during the wet season that livestock owners in this area
need to closely monitor the worm burdens in their animals. Treatment with
ivermectin before the onset of the rains not only delayed the onset of egg
shedding but also controlled clinical helminthiasis. In addition, a temporal
change in the pattern of the appearance of infective larvae on pasture was
observed; the appearance was delayed for about a month after the onset of the
rains. The effect of treatment administered during the rains was a temporary
and a short-Jived relief of infection as evidenced by a brief decline in egg
output: it had no detectable impact on pasture infectivity. These results
suggested that removal of hypobiotic larvae before they resumed development
had the combined benefit of reducing both the severity of clinical
helminthiasis and the level of pasture contamination. This impact was
expressed in improved flock performance and particularly in the improvement
of birth weights that subsequently enhanced kid and lamb survival rates.
Probably due to the high selective pressure exerted on the parasite population
in this treatment regime, evidence of loss of susceptibility to ivermectin was
detected at the end of the study. | en |
dc.language.iso | en | en |
dc.title | The epidemiology and control of gastrointestinal nematodes of small ruminants in a semi-arid area of Kenya with emphasis on hypobiosis of haemonchus contortus | en |
dc.type | Thesis | en |
local.publisher | Faculty of Graduate Studies and Research, Institute of Parasitology McGill University, Montreal | en |