Host specificity of Haemonchus spp. for domestic ruminants in the savanna in northern Ivory Coast

Three Haemonchus species (Haemonchus contortus, Haemonchus placei and Haemonchus similis) live in sympatry in the savanna of North C?te d'Ivoire. Four domestic ruminant hosts (zebu-cattle, taurine-cattle, sheep and goats) share the same pastures throughout the year. Our post-mortem data imply that a Haemonchus spp. circulation exists among the different hosts species in the savanna of North C?te d'Ivoire. Under field conditions, mixed congeneric infections were the rule except in sheep where mono-specific H. contortus infections were the most frequent. The associations H.contortus+H.placei and H.placei+H.similis were dominant in goats and in cattle, respectively. In the populations examined, triple infections occurred in 11.5% of zebu-cattle and 29% of the taurine-cattle. Considering the intensities of infections, H. contortus was the main Haemonchus species of sheep and goats whereas H. similis was very rare in these host species. About 10% of the worms recovered in goats belong to the H. placei species. In cattle, H. contortus was very rare. H. placei was the dominant species in zebu-cattle (58.7% of the identified worms) and in taurine-cattle (73.9%) nevertheless, the proportion of H. similis was higher in zebu-cattle (38.6%) than in taurine-cattle (21.3%). Only few hybrids between H. placei and H. similis were found. The importance of such Haemonchus spp. circulation is discussed.     

Efficacy of febantel against abomasal nematodes and lungworms in cattle

The efficacy of febantel at a dosage of 5 mg/kg (45.5% paste formulation) against inhibited early 4th-stage larvae (EL4) of Ostertagia ostertagi, other nematodes of the abomasum, and Dictyocaulus viviparus was investigated in 4- to 6-month-old Holstein calves that grazed on pasture heavily contaminated with parasites from February 24 to April 1, 1986 (36 days). In Louisiana, this is the first month of a 3-month period in which increasing numbers of inhibition-prone O ostertagi larvae are acquired, and infection risk with D viviparus may remain high. Three of 4 calves that died of lungworm infection during the pasture-exposure period were necropsied. Large numbers of abomasal nematodes, including inhibited O ostertagi larvae, and large numbers of D viviparus were recovered. Twenty-five calves were randomly allotted by equal distribution of body weight to 2 groups and treated on April 4: placebo-treated calves (n = 13) and febantel-treated calves (n = 12). Equal numbers of treated and control calves were killed at 6 and 7 days, respectively, after treatment. Mean numbers of O ostertagi in control cattle were: adults, 4,931; developing 4th-stage larvae (DL4), 1,119; and inhibited EL4, 3,410. Ostertagia lyrata, Trichostrongylus axei, Haemonchus sp, and D viviparus were well distributed in nearly all control calves. Percentage reduction of O ostertagi in treated calves, when compared with controls, was: adults, 83.6%; DL4, 57.8%; and inhibited EL4, 34.8%. Percentage reductions of other species were: O lyrata, 92.6%; T axei adults, 99.3% and 4th-stage larvae (L4), 100%; Haemonchus sp adults, 66.7%, and L4, 64%; D viviparus adults 90.6%, and immature forms, 97.1%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Absence of hypobiosis in abomasal nematodes of sheep and goats in Egypt

A total of 96 abomasa from sheep and goats at the Zagazig abattoir, Sharkia Province, Egypt, were examined, during the four climatic seasons from April 1986 to March 1987, for the presence of adult and larval nematodes. Adults of Trichostrongylus axei were most numerous followed by adult Haemonchus contortus. Adult Ostertagia sp. and Parabronema skrjabini were less prevalent. There was no significant difference between sheep and goats in infection rates, but worm burdens of the nematodes other than Ostertagia sp. were significantly higher (P less than 0.05) in sheep than in goats. The animals were uniformly infected with these parasites throughout the year as there were no significant differences in the incidence or intensity of infections between the four seasons. The numbers of larvae recovered from the wall of the abomasa were small in relation to the total adult worm population throughout the year with a slight increase during the summer. Hypobiosis, therefore, seems not to be important in the life cycle of abomasal nematodes of sheep and goats in Sharkia Province, Egypt.     

Epidemiology of abomasal nematodes of dairy cattle in Hokkaido, northern Japan

The prevalence and intensity of infection with abomasal nematodiasis was studied in dairy cattle of Hokkaido, northern Japan, for successive two years. During the period of March in 1985 to September in 1987, a total number of 393 abomasa of Holstein-Friesian cows was examined for nematode parasites. Nematodes were detected from 75% of the cows. The prevalence of nematode species detected was Ostertagia ostertagi 250 (63.6%), Mecistocirrus digitatus 181 (46.1%), Trichostrongylus axei 85 (21.6%) and Haemonchus sp. 1 (0.3%). The prevalence and population composition of each growth stage varied seasonally in O. ostertagi and M. digitatus. The large percentage of arrested larvae, early L4 O. ostertagi and immature L5 M. digitatus, detected during the mid-winter and the increasing percentage of matured adult populations of both species in early spring revealed the occurrence of the autumn associated arrested development (hypobiosis) phenomenon in bovine abomasum nematodes of Japan.     

Host-parasite checklist of nematodes of domestic ruminants in New Zealand

Extract

Nematodes of domestic ruminants are abundant and widespread throughout New Zealand, and, although the economic importance of some of them is well-recognized, the literature regarding the occurrence, incidence, and distribution of individual species is sparse and very incomplete. A partial explanation of this may be that in diagnostic laboratories in this country, as elsewhere, it is usual for the purposes of routine diagnostic worm counts to identify the parasites at the generic level only. Thus, little information is gained regarding the geographical and seasonal distribution of individual species where more than one species of a genus may occur in the same location in any particular host.     

Faecal bacteria of wild ruminants and the alpine marmot

Faecal samples from 60 red deer (Cervus elaphus), 13 roe deer (Capreolus capreolus), 7 chamois (Rupicapra rupicapra), 41 alpine marmot (Marmota marmota) and soils mixed with deer faeces from the Stelvio National Park were examined for Campylobacter sp. and Salmonella sp. with negative results. The same material, especially deer faeces, was a habitat highly suitable for Yersinia sp.: Y. enterocolitica (two biotypes) was isolated twice, Y. kristensenii (two serotypes) was isolated 19 times, Y. frederiksenii and Y. intermedia were isolated once. Antibiotic-resistant Escherichia coli were isolated from 16 specimens from wild ruminants, one from marmot and two from feeding places.     

Faecal bacteria of wild ruminants and the alpine marmot

Faecal samples from 60 red deer (Cervus elaphus), 13 roe deer (Capreolus capreolus), 7 chamois (Rupicapra rupicapra), 41 alpine marmot (Marmota marmota) and soils mixed with deer faeces from the Stelvio National Park were examined forCampylobacter sp. andSalmonella sp. with negative results.The same material, especially deer faeces, was a habitat highly suitable forYersinia sp.:Y. enterocolitica (two biotypes) was isolated twice,Y. kristen-senii (two serotypes) was isolated 19 times,Y. frederiksenii andY. intermedia were isolated once.Antibiotic-resistantEscherichia coli were isolated from 16 specimens from wild ruminants, one from marmot and two from feeding places.This article was presented as a paper at the 8th International Symposium Enteric Infections and their Control of the World Association of Veterinary Microbiologists, Immunologists and Specialists in Infectious Diseases (Perth, Western Australia, 20 August 1983).     

The significance of inhibition in the parasitic development of abomasal nematodes in New Zealand sheep

Abstract

Extract

Infective larvae of Haemonchus contortus when ingested by sheep normally undergo development through a series of moults to become sexually mature, adults, a process that takes 14 to 15 days (Veglia, 1915 Veglia, F. 1915. The anatomy and life history of the Haemonchus contortus (Rud). 3rd and 4th Rep. Direct. Vet. Res., Union of South Africa, : 348–500.  [Google Scholar]). In some circumstances, however, such larvae may become arrested in their development at an early fourth larval stage 3 to 4 days following ingestion (Blitz and Gibbs, 1971 Blitz, N. M. and Gibbs, H. C. 1971. Morphological characterization of the stage of arrested development of Haemonchus contortus in sheep. Can. J. Zool., 49: 991–995.  [Google Scholar]). A similar phenomenon of arrested or inhibited development has also been recorded in Ostertagia circumcincta and Trichostrongylus axei infections in sheep; in the former again occurring at an early fourth stage, (Sommerville, 1953 Sommerville, R. I. 1953. Development of Ostertagia circumcincta in the absomasal mucosa of the sheep. Nature. Lond., 171: 482–483.  [Google Scholar], 1954 Sommerville, R. I. 1954. The histotropic phase of the nematode parasite Ostertagia circumcincta. Aust. J. agric. Res., 5: 130–140.  [Google Scholar]) and in the latter at a loosely defined “fourth larval stage” (Reid and Armour, 1972 Reid, J. F. S. and Armour, J. 1972. Seasonal fluctuations and inhibited development of gastro-intestinal nematodes of sheep. Res. vet. Sci., 13: 225–229.  [Google Scholar]).     

Seasonal changes in the abomasal nematodes of naturally infected ewes in Moulay-Bouazza (Morocco)

The nematode populations of 93 abomasa of ewes from Middle-Atlas (Morocco) were studied over a period of 3 years. The main species present were Ostertagia circumcincta, Marshallagia marshalli, Trichostrongylus axei and T. vitrinus; less frequent species were O. ostertagi and O. trifurcata. Two peaks of infection were recorded, 1 at the end of winter or the beginning of spring (February--March), and another in autumn (September). The first population peak consisted mostly of O. circumcincta and T. axei, and the second population peak, in autumn, had a high prevalence of M. marshalli and T. vitrinus.     

Cryopreservation of the infective larvae of the common nematodes of ruminants

Exsheathed infective larvae (L 3) of 19 species of nematodes were tested for infectivity in either sheep or cattle after they had been frozen in 0,9% NaCl solution, stored for a relatively short time in the gas phase of liquid nitrogen and subsequently thawed. In addition, 13 of these species were tested after similar storage for up to 18 months. In sheep, Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Nematodirus spathiger and Oesophagostomum columbianum were viable after 2 years of cryopreservation, a mean of greater than 90% of the L 3 being alive when thawed after this period. Similar results were obtained with Chabertia ovina L 3 after 18 months and with Marshallagia marshalli, Trichostrongylus falculatus and Dictyocaulus filaria, after a short period of freezing. On the other hand, Gaigeria pachyscelis and Strongyloides papillosus survived freezing for up to 7 months but neither was viable at the end of this period, nor was exsheathed G. pachyscelis viable without freezing. Most of these infestations were established by inoculating the infective larvae into the abomasum and/or duodenum. M. marshalli, T. falculatus and C. ovina also proved infective after oral dosing. D. filaria, the only other species tested by this route, was not infective when dosed per os after thawing. The infective larvae of the bovine nematodes, Haemonchus placei, Ostertagia ostertagi, Nematodirus helvetianus, Oesophagostomum radiatum, Cooperia pectinata and Cooperia punctata survived freezing for a mean of 26 months, greater than 90% being alive on thawing, but infectivity was generally lower than with the same genera in sheep. Even when not frozen, exsheathed Bunostomum phlebotomum was non-infective. When Cooperia spp. after thawing were tested for infectivity by the oral route, more worms developed in one calf infested orally than in another infested by inoculation into the duodenum. Ova of H. contortus, M. marshalli, O. circumcincta, T. colubriformis, T. falculatus, N. spathiger, C. ovina, H. placei, O. ostertagi, Cooperia spp. and N. helvetianus were recovered from the faeces of animals infested with cryopreserved L 3. No ova of O. columbianum or O. radiatum were recovered from faeces, because differential larval counts were performed before they were patent. Nevertheless, gravid females were obtained post-mortem. Frozen L 3 of N. helvetianus were used to re-establish a pure strain in calves, 2,3 million ova being recovered from infestations with 10 670 L 3 frozen for 26 months. The infectivity of the progeny of frozen L 3 was tested with M. marshalli and C. ovina. In both instances infectivity was high and the worms which developed also produced ova, thus completing the cycle. This appears to be the first report of infective larvae of parasitic nematodes retaining their infectivity after being frozen in liquid nitrogen (gas phase) for longer than 2 years. This is also apparently the first time that M. marshalli T. colubriformis, T. falculatus, T. axei, N. spathiger, C...     

Cryopreservation of some common nematodes of ruminants for up to 11,3 years

Infective larvae of selected batched of the following nematode species from sheep and cattle were examined for survival and infectivity (by injection into either the abomasum, the duodenum, or the jugular vein) after having been stored in liquid nitrogen for 103-136 months: Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagi, Marshallagia marshalli, Cooperia spp., Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus falculatus, Nematodirus spathiger, Nematodirus helvetianus, Oesophagostomum columbianum, Oesophagostomum radiatum, Chabertia ovina and Dictyocaulus filaria. Excluding D. filaria, a mean of 97.7% of the ovine and 96.0% of the bovine nematode larvae were alive when thawed. Compared with previous investigations in this series, little or no reduction occurred with time in either the survival or the viability of the nematodes from cattle, or in the survival of those from sheep. In contrast, the larvae developed poorly in sheep, possibly owing to parenteral treatment of the animals with ivermectin at a dosage of 0.4 mg kg-1, either 6 or 8 days before they were infected.