The pathogenesis of experimental Haemonchus longistipes infection in goats

Establishment of camel isolates of Haemonchus longistipes and Trichostrongylus colubriformis in goats

Two main nematode parasites, Haemonchus longistipes and Trichostrongylus colubriformis, have been reported to cause morbidity and mortality in camels. Although goats are usually reared with camels in the combined animal husbandry system prevailing in Northern India, these parasites have not been reported in goats. Therefore, it was planned to conduct an experimental cross-transmission study of H. longistipes and T. colubriformis isolated from camels and transferred to young goats. Twelve healthy kids (5-6 months) were divided into three groups of four each. Groups I and II were infected orally with third stage infective larvae of H. longistipes and T. colubriformis cultured in the laboratory from faecal isolates from camels, at the rate of 50,000 and 100,000 larvae, respectively; group III comprised uninfected healthy controls. Daily clinical and faecal examinations were made. Body weights and blood haematological indices were measured at weekly intervals. The infection became established in both infected groups, and the animals started passing ova 17 days postinfection. Egg counts varied from 275.00 +/- 248.74 to 6150 +/- 2830.63 eggs g-1. Animals were killed 28 days postinfection. On postmortem examination mature as well as immature worms were recovered from the abomasum and intestine with typical postmortem changes seen in both the groups. Clinical manifestations were weakness and loss of body weight but no diarrhoea. There was a marked fall in haemoglobin and packed cell volume, indicating anaemia in both infected groups.

Interaction of parasitism and nutrition in goats: effects on haematological parameters, correlations, and other statistical associations

Weaned wether goats (n = 144) approximately 6 months of age were placed in a 2 x 3 factorial experiment to test the effects and interaction of two levels of nutrition (growth+maintenance, NUT1; and twice growth+maintenance, NUT2) and three levels of Haemonchus contortus burden (0, 500, and 2000 larvae administered every 2 weeks; W0, W500, and W2000, respectively) on packed cell volume, red blood cell count, total serum protein and leukocytes. The statistical analysis revealed clear and proportionate differences among levels of infection for all variables. A significant (P < 0.05) nutritional effect was also found associated with all the variables except leukocytes. Nutrition by worm load interactions were found for packed cell volume and leukocytes. The neutrophil/lymphocyte ratio was higher in the NUT1-infected animals, leading to the nutrition by worm load interaction for leukocytes. An analysis for the different leukocyte types revealed significant (P < 0.05) differences among infection levels for lymphocytes, while nutrition level was found to be a significant effect for basophil count and immature white cells. Several significant correlations were observed between pairs of variables. Faecal egg output could be predicted from actual worm count in three of the four necropsy periods. The clear differences observed for blood parameters were not present in production traits, suggesting that physiological thresholds may play an important role in framing the metabolic activity of biological organisms. Total serum protein was the best indicator of these effects on production parameters.

Interaction of parasitism and nutrition and their effects on production and clinical parameters in goats

Weaned wether goats (n = 144) approximately 6 months of age were placed in a 2 x 3 factorial design experiment for 5 months to test the main effects and interaction of two levels of nutrition (growth + maintenance, NUT1; twice growth + maintenance, NUT2) and three levels of Haemonchus contortus burden (0, 500 and 2000 larvae administered every 2 weeks: W0, W500 W2000, respectively) on weight, feed intake, level of infection and packed cell volume (PCV). The rationale for the experimental design was based on the lack of information concerning the interaction between nutritional status and worm burden. Results indicated significant effects of worm burden levels on PCV, faecal egg contents (eggs per gram of feces (EPG)), actual worm numbers, feed intake and efficiency of feed utilization. Nutrition x worm burden interactions were also significant for PCV and EPG. However, the differences detected for PCV and actual worm numbers did not translate into large or consistent differences in body weight. Goats on NUT2, after an initial period, showed little difference in body weight, irrespective of worm burden. Within the NUT1 level, W0 kids weighed more than W500 or W2000 kids throughout the study. Although not statistically significant, this constitutes a trend towards an interaction between nutrition and worm burden. In both nutrition levels, there were no body weight differences between W500 and W2000 until the last 14 days. Feed intake was depressed in the first 3 months of the experiment for infected animals, but was subsequently followed by a compensatory reaction. Lower establishment rates, based on actual worm counts, were observed for the higher infection level, but in both infection levels establishment rates tended to decrease with time. Nutrition was found to be more important to counteract the consequences of a parasitic infection than to counteract the establishment of that same infection.

Seasonal fluctuations of gastrointestinal helminths of camels in Kuwait

Over a period of 1 year, from May 1982 to April 1983, the gastrointestinal tracts of 240 camels were examined for the presence of parasitic helminths. The study quantifies the prevalence of gastrointestinal helminths and the seasonal fluctuations in intestinal worm burdens and faecal worm egg counts. Among the three species of cestodes and eight species of nematodes which were recorded for the first time from Kuwait, Trichostrongylus probolurus (93.8%), T. colubriformis (34.2%) and Stilesia vittata (30.0%) were the most prevalent in the small intestine and Camelostrongylus mentulatus (59.6%) in the abomasum. Estimation of the intestinal worm burdens and faecal worm egg counts showed that Trichostrongylus infections were by far the most predominant. The highest worm and egg counts were recorded in June and August, during the hot dry season. This rise is attributed to infections acquired from February to April, during the cool wet season. Possibly the most effective control can be achieved by a critical treatment at the end of the wet season coinciding with the first rise in nematode population.

Haemonchus longistipes Railliet & Henry, 1909 in goats in the Sudan

Haemonchus longistipes specimens were collected from experimentally infected Sudanese goats and camels for morphological studies. The specimens from goats were much smaller than those from camels, but their infectivity to camels was not affected by their passage in goats. Goats inhabiting the same areas as camels in the Sudan were found to be naturally infected with H. longistipes, but sheep were not and were resistant to experimental infection.