Climatic influences on development and survival of free-living stages of equine strongyles: Implications for worm control strategies and managing anthelmintic resistance

Nielsen, Martin K.; Kaplan, Ray M.; Thamsborg, Stig Milan; Monrad, J.; Olsen, Susanne Nautrup

doi:10.1016/j.tvjl.2006.05.009

Cited by 122 publications

(79 citation statements)

References 53 publications

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“…Higher average recovery of L 3 from the stool (165,400 kg -1 DM) and grass samples (14,700 and 13,200 L 3 .kg -1 DM in the GA and GB, respectively) during the dry season was probably due to ideal temperature conditions and low rainfall. These findings agree with those reported by Langrová et al (2003), Bezerra et al (2007), Nielsen et al (2007), Quinelato et al (2008) and Santos et al (2011). Fecal masses play an important role in the development of eggs and larvae, acting as reservoirs for larvae, as observed by Mfitilodze and Hutchinson (1987), Uhlinger (1991), Bezerra et al (2007) and Santos et al (2011).…”

Section: Discussionsupporting

confidence: 92%

Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil

Santos

Souza

Vieira

et al. 2012

Rev. Bras. Parasitol. Vet.

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The presence of cyathostomin larvae is directly associated to climatic conditions of each region. This study aimed to evaluate the ecology of infective larvae on Brachiaria humidicola during the dry and rainy seasons from October 2007 to September 2008 in a tropical region, Rio de Janeiro state, southeastern Brazil. Stools were collected from the rectum of horses naturally infected with cyathostomins at the beginning of the rainy season (October to March) and dry season (April to September). They were divided into four samples of 500 g and deposited on a grass patch of B. humidicola. Seven days later and every 15 days thereafter samples of feces and grass were collected and processed by the Baermann technique. The mean number of larvae recovered from the grass varied according to the season, with greater recovery of larvae during the peak of the dry season (14,700 L 3 .kg -1 DM). There was a statistically significant difference between L 3 recovered from feces and grass, but not between L 3 recovered from the grass base and apex. These results show that the region's climate favors the development and survival of infective cyathostomin larvae throughout the year, with a greater number of larvae during the dry season.Keywords: Infective larvae, wet and dry seasons, Brachiaria humidicola, cyathostomin. ResumoA disponibilidade de larvas de ciatostomíneos está diretamente relacionada com as condições climáticas de cada região. Para avaliar o comportamento das larvas infectantes nos períodos seco e chuvoso em gramínea Brachiaria humidicola, realizou-se um estudo, no período de outubro/2007 a setembro/2008, na região da Baixada Fluminense, RJ, de clima tropical. Amostras de fezes foram coletadas diretamente do reto de equinos naturalmente infectados por ciatostomíneos, no início do período chuvoso (outubro a março) e seco (abril a setembro), divididas em quatro amostras de 500 g e depositadas em um canteiro formado por gramínea B. humidicola. Sete dias após o depósito e, posteriormente, a cada 15 dias, amostras de fezes e gramíneas, foram coletadas às 8 horas e processadas pela técnica de Baermann. O número médio de larvas recuperadas da gramínea variou conforme os períodos, ocorrendo maior recuperação no ápice do período seco (14.700 L 3 .kg -1 . MS). Diferença significativa ocorreu entre a contagem de L 3 recuperadas das fezes e gramínea e não significativa entre as de L 3 recuperadas nas duas alturas da gramínea. Concluiu-se que as condições climáticas da região favorecem o desenvolvimento e a sobrevivência de larvas infectantes de ciatostomíneos durante todo o ano, com maior disponibilidade no período seco.Palavras-chave: Larvas infectantes, períodos chuvoso e seco, Brachiaria humidicola, ciatostomíneos.

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Section: Discussionsupporting

confidence: 92%

Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil

Santos

Souza

Vieira

et al. 2012

Rev. Bras. Parasitol. Vet.

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“…Furthermore, the concept is not always well understood. For example, the term refugia has been defi ned by some authors as the proportion of the parasite population that escapes treatment, this being principally the larval population on pasture (Van Wyk 2001;Nielsen et al 2007; Torres-Acosta and Hoste 2008). However, this defi nition ignores the fact that resistance can only be delayed by susceptible genotypes contributing offspring to subsequent generations, i.e.…”

Section: Maintenance Of Refugia Of Anthelmintic-susceptible Worm Genomentioning

confidence: 99%

Managing anthelmintic resistance: Is it feasible in New Zealand to delay the emergence of resistance to a new anthelmintic class?

Leathwick

Hosking

Bisset

et al. 2009

New Zealand Veterinary Journal

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The recent registration in New Zealand of the first new class of broad-spectrum anthelmintic, for use against nematode parasites of ruminants, in nearly three decades has raised the possibility that parasite management practices could be improved to minimise the emergence of resistance to the new drug. A review of knowledge pertaining to the selection of anthelmintic resistance in nematode parasites of sheep highlights a number of management practices which could be altered to achieve this. A number of previously common practices such as whole-flock treatment of adult ewes around lambing, and treatment of lambs as they are moved onto pastures with low parasite contamination have been clearly identified as high risk for selecting resistant parasites. Once high-risk practices have been identified steps can be taken to either eliminate their use or mitigate the associated risk. Much of the focus on the management of resistance around the world is on the retention of susceptible genotypes in refugia. While approaches to retaining unselected parasites are likely to vary around the world, empirical studies indicate that the practice is likely to be effective at slowing the development of resistance. The challenge for farmers and advisors will be to strike a balance between retaining sufficient susceptible parasites to usefully delay the development of resistance while not unduly compromising animal performance and farm profitability. The merits of combining different classes of anthelmintic in order to slow the development of resistance remains somewhat contentious in some countries. However, the attributes of oral anthelmintics are such that they seem likely to meet most, if not all, of the criteria for combinations to be highly effective at slowing the build-up of resistance in nematode parasites. It is evident that considerable progress has been made in understanding the factors involved in selecting anthelmintic-resistant nematodes since the last broad-spectrum anthelmintic class was released in the early 1980s. Therefore, it should be possible to manage a new class of anthelmintic in such a way as to significantly extend its effective life. The challenge is likely to be in convincing farmers of the merits of adopting such pro-active strategies.

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“…Outro agravante é o fato de haver pouca perspectiva de surgimento de um novo grupo químico de anti-helmínticos para equinos (15) . Por isso, é muito importante o conhecimento da real situação da susceptibilidade das populações de nematódeos aos antiparasitários, dentro das diferentes características das propriedades.…”

Section: Introductionunclassified

Eficácia Anti-Helmíntica Da Ivermectina Em Equinos: Exames Coproparasitológicos E Hematológicos

et al. 2018

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ResumoO objetivo do presente estudo foi avaliar a eficácia da ivermectina a 2% em equinos, através de exames coproparasitológicos e hematológicos. O experimento foi realizado em uma fazenda no município de Uberlândia, MG. Foram utilizados 24 equinos, de três a oito anos, divididos em dois grupos, conforme valores dos OPG. Contagens de OPG e coproculturas foram realizadas nos dias D0, D+7 e D+14. Os animais foram tratados com a formulação pasta a base de ivermectina 2%, na dose de 200 mcg/kg, via oral. Amostras de sangue foram coletadas nos dias D0, D+7 e D+14 para avaliação dos parâmetros hematológicos. A presença de ovos, característicos da família Strongylidae e identificação de larvas características de ciatostomíneos demonstrou o parasitismo dos animais por pequenos estrôngilos. Nos D+7 e D+14 houve a redução significativa do OPG no grupo tratado com eficácia de 99,5 e 99,7%, respectivamente. Observou-se tendência do quadro eritrocitário manter-se próximo aos limites inferiores e discreta leucocitose com neutrófilos próximos dos valores superiores. Pode-se inferir que a ivermectina é eficaz contra os ciatostomíneos e alterações hematológicas significativas não foram observadas. Palavras-chave: ciatostomíneos; equinos; nematódeos; OPG. AbstractThe aim of the present study was to evaluate the efficacy of ivermectin at 2% in horses, through coproparasitological and hematological exams. The experiment was performed at a farm in the city of Uberlândia, Minas Gerais State. Twenty-four horses were used, ranging from 3 to 8 years of age, divided into 2 groups according to EPG values. EPG counts and coprocultures were performed on days D0, D+7 and D+14. The animals were treated with the ivermectin 2%-based paste formulation at a dose of 200 mcg/kg, orally. Blood samples were collected on days D0, D+7 and D+14 for evaluation of haematological parameters. The presence of eggs that are characteristic of the Strongylidae family and the identification of larvae that are characteristic of cyathostomins demonstrated the parasitism of the animals by small strongyles. At D+7 and D+14 there was a significant reduction of EPG in the treated group with an efficacy of 99.5 and 99.7%, respectively. A

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Climatic influences on development and survival of free-living stages of equine strongyles: Implications for worm control strategies and managing anthelmintic resistance

Cited by 122 publications

References 53 publications

Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil

Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil

Managing anthelmintic resistance: Is it feasible in New Zealand to delay the emergence of resistance to a new anthelmintic class?

Eficácia Anti-Helmíntica Da Ivermectina Em Equinos: Exames Coproparasitológicos E Hematológicos

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