Population dynamics of Trichostrongylus colubriformis in sheep: The effect of infection rate on the establishment of infective larvae and parasite fecundity

Dobson, R.J.; Waller, P.J.; Donald, A.D.

doi:10.1016/0020-7519(90)90150-l

Cited by 103 publications

(28 citation statements)

References 17 publications

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“…They suggested that fecundity, like establishment, was similarly affected at immunological recognition threshold levels. According to Dobson et al (1990) density-dependent effects (parasite competition/crowding) could cause a decline in fecundity when worm population surpassed 3000, which was the case for several animals in the present study, which had more than T T T T 3000 T. colubriformis worms. However, there was no association between total burden x eggs/female (r = -0.068).…”

Section: Discus Discus Discus Discus Discussion and Conclusion Sion supporting

confidence: 49%

“…Dobson et al (1990) reported that T. colubriformis fecundity in sheep remained high (about 600 eggs/day) for five weeks at the low infection rate, but only maintained this level for three weeks and one week at the medium and high rates, respectively. They suggested that fecundity, like establishment, was similarly affected at immunological recognition threshold levels.…”

Section: Discus Discus Discus Discus Discussion and Conclusion Sion mentioning

confidence: 99%

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Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

2007

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The study was carried out to evaluate the relationship of inflammatory intestinal cells with the resistance to Trichostrongylus colubriformis infections in three breeds of sheep (Santa Ines, Suffolk and Ile de France), naturally infected. Mast cells, eosinophils, and globule leucocytes were enumerated in intestinal mucosa. Histamine concentration was estimated in intestinal tissue samples and the length of male and female specimens were determined. The three breeds of sheep showed similar cellular response in the small intestine mucosa (P>0.05). There was extensive variation among sheep in the parasitological and inflammatory cell variables, even in lambs of the same breed. In general, animals presenting less inflammatory cells had a larger worm burden, higher fecal egg counts, and larger T. colubriformis worms. The inflammatory cells possibly impaired the parasite's establishment, development, and survival.

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Section: Discus Discus Discus Discus Discussion and Conclusion Sion supporting

confidence: 49%

Section: Discus Discus Discus Discus Discussion and Conclusion Sion mentioning

confidence: 99%

Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

2007

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“…Dobson et al (1990) made a cohort study using levamisole resistant and susceptible strains of Trichostrongylus colubriformis, whereas Roepstorff et al (1996) used pyrantel resistant and susceptible strains of Oesophagostomum dentatum in their study. But this approach to cohort studies results only in two different cohorts and depends on availability of solidly resistant strains.…”

Section: Discussionmentioning

confidence: 99%

Molecular and parasitological tools for the study ofAscaridia gallipopulation dynamics in chickens

et al. 2010

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Experiments were first conducted to compare and evaluate different methods of Ascaridia galli larval recovery from the chicken intestine. The number of larvae recovered from the intestinal wall of chickens infected with 1000 embryonated A. galli eggs and killed 15 days post infection (p.i.) by three methods (ethylenediamine tetraacetic acid [EDTA], pepsin digestion and scraping) were compared. The EDTA and pepsin digestion were found to be the most efficient methods with no significant difference (P!0.05) in the number of recovered larvae between the two. Subsequently, three different A. galli cohorts were established using the polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) technique. A 533-bp long region of the cytochrome c oxidase subunit 1 gene of the mitochondrial DNA was targeted and 22 A. galli females were allocated to three different haplotypes. The four females with the highest embryonation rate from each haplotype group (total 12 females) were selected and used to inoculate each of 12 chickens with a dose of 1000 embryonated eggs. The chickens were killed 15 days p.i. and A. galli larvae were recovered from the small intestinal wall by the EDTA method and by sieving the lumen content on a 90 mm sieve. DNA of 40 larvae from each of the three different haplotypes was extracted using a worm lysis buffer, and PCR-RFLP analysis of these larvae revealed the same haplotype as that of their maternal parent. The identification of distinguishable cohorts may be a powerful tool in population studies of parasite turnover within the animal host.

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“…Médias das contagens absolutas de hemácias, leucócitos, linfócitos, eosinófilos, volume globular médio (VG) e proteína total plasmática (PTP) do G1 -controle, G2 -larvas inativas, G3 -larvas inativadas + alho in natura e G4 = alho in natura antes aos tratamentos (dia -6) e 24, 60, 84, 120 e 144 dias depois. DONALD, 1990). Em H.contortus, a produção de ovos e a carga parasitária estão intimamente associadas e ambas diminuem após 20-24 semanas de ingestão contínua de larvas (BARGER et al, 1985).…”

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Fito-bioterapia no controle de nematódeos gastrointestinais de ovinos

et al. 2013

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ResumoA resistência parasitária e a tendência dos últimos anos de mudança para sistemas orgânicos tem resultado em diversas alternativas de manejo animal como a seleção de raças resistentes, integração com outras espécies animais, fitoterapia, fungos nematófagos, vacinas contra nematódeos, entre outros. Visando uma alternativa para controle da verminose ovina, objetivou-se analisar o efeito da administração de larvas inativadas de Haemonchus associadas ou não a alho in natura no controle de nematódeos gastrointestinais em ovinos naturalmente infectados. Para tanto, 32 ovinos foram avaliados por até 144 dias após tratamentos com larvas inativadas de Haemonchus e/ou alho in natura, quanto à diminuição da eliminação de ovos nas fezes (taxa de Redução na Contagem de Ovos nas Fezes -RCOF), eficiência destes tratamentos sob os gêneros de helmintos e alterações hematológicas. Observou-se aumento significativo na contagem de OPG dos grupos G1 (controle) e G4 (alho in natura). Ao final do experimento observou-se menor contagem de OPG no G3 (larvas inativadas + alho in natura) em relação ao G1, mas sem diferença significativa entre o G3 e os outros tratamentos. Quanto a RCOF, verificou-se redução média de 44% na contagem de ovos do grupo G2 (larvas inativadas) e do grupo G3 e um aumento de 44% no grupo G4. A eficácia dos tratamentos sob o gênero Haemonchus variou de 0 a 77%, sendo esta ultima taxa observada 67 dias no G3, justamente 7 dias depois de observado aumento significativo de linfócitos. Concluiu-se neste estudo que o alho in natura administrado na concentração de 2,5mg/Kg não foi capaz de reduzir a carga parasitária dos ovinos, mas que, quando associado a administração de larvas inativadas de Haemonchus pode ter contribuído como imunoestimulante e que a redução dos ovos eliminados nas fezes dos ovinos tratados com larvas inativadas, apesar de insuficiente para ser considerado um método de controle eficaz, demonstra a possibilidade de viabilidade no uso de vacinas contra Haemonchose. Palavras-chave: Fitoterapia, bioterapia, verminose, pequenos ruminantes AbstractThe parasitic resistance and the tendency of recent years to shift to organic systems has resulted in several alternative animal management as the selection of resistant breeds, integration with other animal species, phytotherapy, nematophagous fungi, nematodes vaccines, among others. Looking for an alternative control of nematode parasites of sheep, this paper aimed to analyze the effect of administration of inactivated larvae of Haemonchus and fresh garlic on the level infection with gastrointestinal nematodes in naturally infected sheep. Therefore, 32 animals were monitored for 144 days after phyto-biotherapy treatments in relation to reduction of parasite eggs (egg reduction rate -FECR), these treatments under the genres of helminths and hematological changes. It was observed significant increase in the EPGs of G1 (control group) and G4 (fresh garlic). At the end of the experiment observed lower EPG in G3 (inactivated larvae + fresh garlic) compared to...

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Population dynamics of Trichostrongylus colubriformis in sheep: The effect of infection rate on the establishment of infective larvae and parasite fecundity

Cited by 103 publications

References 17 publications

Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

Relationship of intestinal histology with the resistance to Trichostrongylus colubriformis infection in three breeds of sheep

Molecular and parasitological tools for the study ofAscaridia gallipopulation dynamics in chickens

Fito-bioterapia no controle de nematódeos gastrointestinais de ovinos

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