Compilation of 29 years of postmortem examinations identifies major shifts in equine parasite prevalence from 2000 onwards.

Horses are infected by a wide range of parasite species that form complex communities. Parasite control imposes significant constraints on parasite communities whose monitoring remains, however, difficult to track through time. Postmortem examination is a reliable method to quantify parasite communities. Here, we compiled 1,673 necropsy reports accumulated over 29 years, in the reference necropsy centre from Normandy (France). The burden of non-strongylid species was quantified and the presence of strongylid species was noted. Details of horse deworming history and the cause of death were registered. Building on these data, we investigated the temporal trend in non-strongylid epidemiology and we determined the contribution of parasites to the deaths of horses throughout the study period. Data analyses revealed the seasonal variations of non-strongylid parasite abundance and reduced worm burden in race horses. Beyond these observations, we found a shift in the species responsible for fatal parasitic infection from the year 2000 onward, whereby fatal cyathostominosis and Parascaris spp. infection have replaced cases of death caused by Strongylus vulgaris and tapeworms. A concomitant break in the temporal trend of parasite species prevalence was also found within a 10 year window (1998-2007) that has seen the rise of Parascaris spp. and the decline of both Gasterophilus spp. and tapeworms. A few cases of parasite persistence following deworming were identified, which all occurred after 2000. Altogether, these findings provide insights into major shifts in non-strongylid parasite prevalence and abundance over the last 29 years. They also underscore the critical importance of Parascaris spp. in young equids.

Prevalencia de infecciones por estróngilos digestivos en un rebaño ovino del estado Aragua en la época de lluvia / Prevalence of digestive strogyles infections in an Aragua state ovine herd during rainy season

El parasitismo gastrointestinal en los ovinos representa una importante limitante en la explotación de esta especie y dentro de estas infecciones, las estrongilidosis son la de mayor impacto negativo. Con el objetivo de determinar la fluctuación de las infecciones por estróngilos digestivos en animales desparasitados, se examinó coproscópicamente (técnica de Mc Master) una muestra estadística de 70 ovinos, distribuidos proporcionalmente en cuatro grupos de edad. Grupo 1: ovinos de 0 a 70 días de edad (n=5); Grupo 2:70 días a 12 meses (n= 26); Grupo 3: hembras> 12 meses, gestantes, lactantes o vacías (n= 36); Grupo 4: semestrales (n= 3) durante 6 meses. Se calculó la prevalencia, carga parasitaria y se efectuaron coprocultivos cada mes. Se obtuvo un valor de prevalencia promedio del rebaño de 43,64%. Las cargas parasitarias (HPG promedio o abundancia) fueron para el grupo 1= 1210,0 ± 69; grupo 2= 378,6 ± 88; grupo 3 = 385,8 ± 64; grupo 4= 155,6 ± 61; los mayores contajes individuales se observaron en el grupo 2. De los coprocultivos se identificaron larvas infectivas (L3) de Haemonchus contortus durante todo el período de estudio. No se halló diferencia estadística cuando se compararon los noveles de carga parasitaria entre grupos de edad. Las condiciones climáticas consideradas (precipitación, temperatura y humedad ambiental relativa media), se encontraron dentro del rango favorable para el desarrollo y supervivencia de las formas preparasíticas en los estróngilos durante todo el período.

Elimination of mucosal cyathostome larvae by five daily treatments with fenbendazole.

The efficacy of five daily treatments with 7.5 mg fenbendazole/kg bodyweight against mucosal cyathostome larvae was evaluated in 20 12- and 24-month-old ponies with naturally acquired cyathostome infections. After three weeks communal grazing on infected pasture and six weeks indoors, one group of 10 ponies were treated. Six weeks later, both groups of ponies were humanely destroyed and their burdens of large intestinal cyathostome worms, including luminal parasites and mucosal larvae, were assessed. In the control animals approximately 7 per cent of the total worm burden was present in the gut lumen and 93 per cent was present as larvae in the large intestinal mucosa. The efficacy of fenbendazole against the luminal cyathostomes was 90.7 per cent (P < 0.01). The total numbers of mucosal larvae, recovered after digestion, were reduced by 95.3 per cent (P < 0.0005); mucosal late third and fourth stage larvae were reduced by 99.4 per cent (P < 0.0001), and early inhibited third stage larvae by 91.5 per cent (P < 0.005).

The efficacy of ivermectin against Strongyloides papillosus in cattle.

The efficacy of ivermectin was evaluated against Strongyloides papillosus in four controlled trials in cattle. Thirty-four animals were inoculated subcutaneously with S. papillosus 3rd stage larvae 14-24 days before treatment. At 7-14 days after treatment, calves were slaughtered and the number of adult S. papillosus present in the small intestine counted. Faecal egg counts were carried out before and after treatment. Seventeen control animals received a single subcutaneous injection of vehicle solution at a dose volume of 1 ml/50 kg body weight, and 17 calves were treated once with ivermectin at 200 mcg/kg b.w. using a 1% injectable solution (IVOMEC Injection Merck & Co., Inc.), subcutaneously. The control animals had a mean burden of 5,913 worms, while ivermectin significantly (p less than 0.01) reduced the number of adults S. papillosus by more than 99%. There was a greater than 99% reduction in the faecal egg count of treated animals at the last faecal examination compared with that pre-treatment.