ABSTRACT
Benzimidazoles are the most common anthelminthic used for control of gastrointestinal nematodes of goats in the Brazilian semi-arid region. Resistance to these compounds in the nematode Haemonchus contortus has been associated with single nucleotide polymorphisms (SNP) in codons 167 (F167Y) and 200 (F200Y) on the ß-tubulin isotype 1 gene. To determine the resistance profile to benzimidazoles of populations of H. contortus of goats of Brazilian semi-arid region, larvae of 29 populations of these nematodes were individually genotyped by real time PCR using a Taqman assay. The percentage of larvae homozygous (RR) for SNP F200Y was relatively low (18.9%), particularly when compared to SNP F167Y (32.7%), indicating that the latter has more relevance in this region. However, the associations between these two SNP demonstrate percentages of resistance ranging from 34.7% to 100% between populations, being the highest percentages for homozygous individuals resistant for the mutation 167 and susceptible to mutation 200 (RR-F167Y/F200Y-SS: 26.7%), followed by combination of heterozygous for both mutations (F167Y-SR/F200Y-SR: 22.8%). These results indicate high levels of resistance in populations of H. contortus of goats in the Brazilian semi-arid region, and thus ineffective antiparasitic control with the use of benzimidazoles in the region.
ABSTRACT
In order to investigate whether pigs can be infected by Leishmania infantum, a serological and parasitological study was carried out on swine in the Jequié municipality, Northeast of Brazil. Anti-Leishmania infantum antibodies were detected in 37 out of 92 swine (40.2%), by two different assays: an anti-L. infantum lysate and an anti-K39 recombinant protein ELISA. An experimental study was also carried out to verify the susceptibility of domestic pigs to L. infantum infection. Three sows inoculated with 10(8) stationary-phase infective L. infantum promastigotes (26% metacyclic promastigotes) per kilogram of body weight produced anti-Leishmania antibodies until the end of the experiment, 11 months later. No parasites, however, could be visualized through optical microscopy of spleen, liver and bone marrow or by in vitro culture of these organs. Homogenates of these organs were also inoculated in hamsters, without producing infection. No Leishmania DNA was detected by polymerase chain reaction (PCR) in sand flies fed on these animals. The results indicate that domestic pigs bitten by L. infantum-infected vectors in the endemic area do not display a full infection pattern, and the positive association in endemic areas between the presence of swine and infection in canines may not be ascribable to the former acting as a parasite reservoir.
