Angiostrongylus cantonensis is the etiologic agent of eosinophilic
meningoencephalitis in humans. Cases have been recorded in many parts of the world,
including Brazil. The aim of this study was to compare the differences in the biology
and morphology of two different Brazilian haplotypes of A. : ac8 and
ac9. A significantly larger number of L1 larvae eliminated in the faeces of rodents
at the beginning of the patent period was observed for ac9 haplotype and compared to
the total of L1 larvae eliminated, there was a significant difference between the two
haplotypes. The ac9 haplotype showed a significant difference in the proportion of
female and male specimens (0.6:1), but the same was not observed for ac8 (1.2:1). The
morphometric analysis showed that male and female specimens isolated from ac8
haplotype were significantly larger with respect to body length, oesophagus length,
spicule length (male) and distance from the anus to the rear end (female) compared to
specimens from ac9. The morphological analysis by light microscopy showed little
variation in the level of bifurcations at the lateral rays in the right lobe of the
copulatory bursa between the two haplotypes. The biological, morphological and
morphometric variations observed between the two haplotypes agree with the observed
variation at the molecular level using the cytochrome oxidase subunit I marker and
reinforce the possible influence of geographical isolation on the development of
these haplotypes.
Helminth parasites have been studied as potential accumulators for different pollutants. Echinostoma paraensei is a foodborne trematode whose vertebrate host, the rodent Nectomys squamipes, is naturally exposed to environmental pesticides. However, little information exists regarding the pesticide's effects on helminths. This study investigated the morphological effects on the trematode, E. paraensei, after experimental Roundup® herbicide exposure, in concentrations below those recommended for agricultural use. After two hours of exposure, scanning electron microscopy (SEM) showed changes to the tegument, such as furrowing, shrinkage, peeling, spines loss on the peristomic collar, and histopathological evidence of altered cells in the cecum and acinus vitelline glands with vacuoles and structural changes to the muscular layers. Glycidic content was decreased, primarily in the connective tissue. As E. paraensei is an intestinal parasite of the semi-aquatic wild rodent, N. squamipes, it is predisposed to pesticide exposure resulting from agricultural practices. Therefore, we emphasize the need to evaluate its impact on helminth parasites, due to their pivotal role in regulating host populations.
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