Haematological observations on the helminthiasis caused by Haemonchus contortus in Nigerian dwarf sheep

Prevalence and seasonal changes in the population of gastrointestinal nematodes of small ruminants in the semi-arid zone of north-eastern Nigeria

A survey was carried out to determine the prevalence and seasonal abundance of the egg and adult stages of nematode parasites of sheep and goats in the semi-arid zone of north-eastern Nigeria between January and December 2002. Faecal samples collected from 102 sheep and 147 goats and examined by the modified McMaster technique using saturated solution of sodium chloride as the floating medium revealed that 44 (43.1%) and 82 (55.8%) of the samples, respectively, contained at least one nematode egg type. Three nematode egg types were recovered with strongyle egg type (22.5% in sheep and 35.4% in goats) being the most prevalent followed, respectively, by Trichuris (5.9% in sheep and 4.1% in goats) and Strongyloides (4.9% in sheep and 4.1% in goats) egg types. Mean faecal egg counts were generally moderate in both sheep (1052+/-922 strongyle, 1000+/-590 Strongyloides and 380+/-110 Trichuris eggs, respectively, per g of faeces) and goats (2092+/-3475 strongyle, 958+/-854 Strongyloides and 683+/-512 Trichuris eggs, respectively, per g of faeces) and showed the same trend irrespective of the age or sex of the animals. The prevalence and counts of strongyle nematode eggs showed a definite seasonal sequence that corresponded with the rainfall pattern in the study area during the period. In both sheep and goats, counts of strongyle egg type increased with the rains and reached peak levels at about the peak of the rainy season in September. The other egg types encountered during the study did not show much variation with the season of the year. Out of the 45 sheep and 75 goats examined at necropsy, 27 (60%) and 39 (52%), respectively, contained adult nematode species. Seven genera of adult nematodes including Strongyloides, Trichostrongylus, Haemonchus, Trichuris, Cooperia, Oesophagostomum and Bunostomum species were encountered during the study. Bunostomum species were recorded only in sheep. Adult worm burdens were generally low and showed seasonal variation that corresponded with the rainfall pattern in the study area during the period. Haemonchus and Trichostrongylus species attained peak counts together in both goats (June) and sheep (August). Strongyloides species were encountered throughout the year in both sheep and goats irrespective of the season. Other genera of nematodes encountered occurred in very low numbers and did not allow any meaningful comparison of seasonal sequence. The results suggest that Haemonchus, Trichostrongylus and Strongyloides species may be the major contributors to small ruminant helminthiasis in the study area.

The haematological and biochemical effects of the gastrointestinal nematodes prevalent in camels (Camelus dromedarius) in central Saudi Arabia

Coprological examinations on 1200 Najdi camels (Camelus dromedartus) in the Gassim region of central Saudi Arabia between October 1992 and September 1993 revealed the presence of strongyle-type, Nematodirus and Strongyloides eggs. In addition, examination of the gastrointestinal tracts of 240 camels slaughtered in different abattoirs in the Gassim region from March to August 1994 revealed 11 species of helminths. Infection with gastrointestinal trichostronglyes resulted in normocytic, normochromic anaemia. Adult infected camels showed leukocytosis, a decrease in total serum protein concentration and increases in blood urea concentration and in serum creatine phosphokinase activity.

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.

The epidemiology of helminthosis in small ruminants under the traditional husbandry system in eastern Nigeria

The epidemiology of helminth infections in West African dwarf sheep and goats under the traditional husbandry system prevailing in the derived savanna area of eastern Nigeria was studied for 12 months. The infections observed were due to Haemonchus contortus (87.1%), Trichostrongylus spp. (63.8%), metacestodes of Taenia hydatigena (30.2%), Oesophagostomum columbianum (22.4%), Strongyloides sp. (18.8%), Cooperia spp. (17.2%), Gaigeria pachyscelis (6.0%), Moniezia expansa (6.0%), Bunostomum trigonocephalum (4.3%), Trichuris ovis (3.5%), Capillaria sp. (0.9%) and paramphistomes (0.9%). Mixed infections were most prevalent. The endemicity of parasitic gastroenteritis in the area was indicated by the high prevalence of the helminths irrespective of the season of the year. The overall trend in helminthosis in these animals was that of an escalating worm burden during the period of confinement (April - October) and a low worm burden when animals were allowed free range (November - March), these periods corresponding to the cropping and harvest seasons respectively. A strong positive correlation (r = 0.73; p less than 0.01) was obtained between the mean strongyle worm burden and the eggs per gram (EPG) of faeces. A single treatment with a broad spectrum anthelmintic followed by movement into clean sheds at the beginning of confinement is suggested to give control of helminthosis in small ruminants in this area.

The pathogenesis of experimental Haemonchus longistipes infection in camels

The pathogenesis and clinical signs of Haemonchus longistipes infection were studied in four experimentally infected camels two of which were adults and the other two were young. In the former animals, an acute infection developed, characterized by mucoid diarrhoea, anorexia, anaemia, loss of body weight, oedema of the lower parts of the limbs, general malaise and death at 8-10 weeks post-infection. In the two younger camels, a less dramatic disease was encountered with less severe symptoms and no oedema, but also terminating fatally at 19-20 weeks post-infection. Parasitological, haematological and biochemical parameters were determined during the course of the infection and were mostly comparable with those usually encountered in haemonchosis of other animals.

The pathogenesis of experimental Haemonchus longistipes infection in goats

Goats are highly susceptible to Haemonchus longistipes and could therefore serve as an inexpensive model to study camel haemonchosis. The course of the disease in goats is similar to that in camels and to H. contortus infection in sheep and goats. Unlike the age-dependency of camel haemonchosis, however, the severity of H. longistipes infection in goats is dose-dependent and varies from mild to hyperacute.

Experimental Ancylostoma tubaeforme infection of cats: changes in blood values and worm burden in relation to single infections of varying size

Worm-free cats about 12 weeks old were infected with 100, 500, 1,000 and 2,000 third-stage larvae (L3) of Ancylostoma tubaeforme. The changes in packed cell volume (PCV) and haemoglobin content were monitored, and the worm populations developing in each infection recorded. Cats receiving infection doses of 1,000 L3 and above showed morbidity symptoms by the third week and a rapid decline especially in the PCV value. The low dose rates (500 L3 and below) produced an apparently symptomless condition without pronounced changes in the blood values. Adult hookworm populations were linearly related to the logarithm of the dose of infective larvae administered, but there was a lower female to male ratio (FMR) at high dose levels. No significant size differences were observed in the adult hookworm populations.