Anthelmintic efficacy of ivermectin and abamectin, administered orally for seven consecutive days (100 µg/kg/day), against nematodes in naturally infected pigs.

The present study aimed to evaluate ivermectin and abamectin, both administered orally in naturally infected domestic swine, as well as analysing if the EPG (eggs per gram of faeces) values were equivalent with the ivermectin and abamectin efficacy obtained by parasitological necropsies. The animals were randomly selected based on the average of three consecutive EPG counts of Strongylida, Ascaris suum and Trichuris for experiment I, and of Strongylida and Trichuris for experiment II. After the random draw, eight animals were treated, orally, during seven consecutive days with 100 µg/kg/day ivermectin (Ivermectina® premix, Ouro Fino Agronegócios), eight other animals were treated, orally, during seven consecutive days with 100 µg/kg/day abamectin (Virbamax® premix - Virbac do Brasil Indústria e Comércio Ltda.), and eight pigs were kept as controls. EPG counts were performed for each individual animal at 14th day post-treatment (DPT). All animals (control and treatment) were necropsied at the 14th DPT. The results from both experiments demonstrate that both ivermectin and abamectin, administered orally for a continuous period of seven days, at a daily dosage of 100 µg/kg, were highly effective (>95%) against Hyostrongylus rubidus, Strongyloides ransomi, Ascaris suum and Metastrongylus salmi. Against Oesophagostomum dentatum, abamectin presented over 95% efficacy against both evaluated strains, while ivermectin reached other strain as resistant. Regarding T. suis, both ivermectin and abamectin were effective (efficacies >90%) against one of the tested strains, while the other one was classified as resistant. Furthermore, the EPG values were equivalent with the ivermectin and abamectin efficacy obtained by parasitological necropsies.

Helminth fauna of bovines from the Central-Western region, Minas Gerais State, Brazil / Fauna helmintológica de bovinos da região Centro-oeste do Estado de Minas Gerais, Brasil

Seventy-six naturally infected bovines, males and females of mixed breed, aged 8 to 12 months-old, were necropsied. The results of necropsy revealed the presence of 9 helminth genera and 16 species, with the following prevalence and mean infection intensity: Haemonchus placei (100.0 percent; 3895.5); Haemonchus similis (29.0 percent; 159.6); Cooperia punctata (100.0 percent; 5595.0); Cooperia spatulata (32.9 percent; 137.8); Cooperia pectinata (34.2 percent; 1010.5); Trichostrongylus axei (69.7 percent; 239.2); Trichostrongylus colubriformis (10.5 percent; 10.8); Trichostrongylus longyspicularis (2.6 percent; 0.5); Ostertagia ostertagi (2.6 percent; 3.1); Ostertagia lyrata (2.6 percent; 1.5); Ostertagia trifurcata (1.3 percent; 0.3); Oesophagostomum radiatum (94.7 percent; 470.9); Trichuris discolor (47.4 percent; 32.5); Strongyloides papillosus (1.3 percent; 0.1); Capillaria bovis (9.2 percent; 1.0) and Bunostomum phlebotomum (2.6 percent; 0.3). The mean parasitic load was 11,558.5 helminths per bovine. Of the 76 necropsied bovine, 92.1 percent were infected by 3 to 7 helminth species. Only 7.9 percent of hosts were parasitized by 8 different helminth species. This study includes the first report of the species Ostertagia lyrata and Ostertagia trifurcata in Minas Gerais state. It should be emphasized that while identifying the helminths collected during necropsy in the present work, observation revealed that an inversion in the mean parasitic intensity is occurring, showing diminishing numbers of Cooperia and an increase in Haemonchus compared to the values reported in the literature.

A prevalência e a intensidade de parasitismo por diferentes espécies de helmintos foram estudadas em bovinos da microrregião de Formiga, região Centro-oeste de Minas Gerais. Para tanto, foram necropsiados 76 bovinos naturalmente infectados, machos e fêmeas, SRD (sem raça definida) e de oito a 12 meses de idade. Os resultados necroscópicos revelaram a presença de nove gêneros e 16 espécies de helmintos, com a seguinte prevalência e média de intensidade de infecção: Haemonchus placei (100,0 por cento; 3895,5); Haemonchus similis (29,0 por cento; 159,6); Cooperia punctata (100,0 por cento; 5595,0); Cooperia spatulata (32,9 por cento; 137,8); Cooperia pectinata (34,2 por cento; 1010,5); Trichostrongylus axei (69,7 por cento; 239,2); Trichostrongylus colubriformis (10,5 por cento; 10,8); Trichostrongylus longyspicularis (2,6 por cento; 0,5); Ostertagia ostertagi (2,6 por cento; 3,1); Ostertagia lyrata (2,6 por cento; 1,5); Ostertagia trifurcata (1,3 por cento; 0,3); Oesophagostomum radiatum (94,7 por cento; 470,9); Trichuris discolor (47,4 por cento; 32,5); Strongyloides papillosus (1,3 por cento; 0,1); Capillaria bovis (9,2 por cento; 10) e Bunostomum phlebotomum (2,6 por cento; 0,3). A carga parasitária média foi de 11.558,5 helmintos por animal. Dos 76 bovinos necropsiados, 92,1 por cento estavam infectados por três a sete espécies de helmintos. Apenas 7,9 por cento dos hospedeiros mostravam-se parasitados por oito espécies diferentes de helmintos. Este estudo mostra o primeiro relato das espécies Ostertagia lyrata e Ostertagia trifurcata no Estado de Minas Gerais. É importante ressaltar que, no presente trabalho, por meio da identificação dos helmintos colhidos nas necropsias, foi possível observar que está ocorrendo uma inversão na intensidade parasitária média, com uma diminuição no número de Cooperia e um aumento nos valores de Haemonchus, em comparação com os valores relatados na literatura.