Short report: Genetic variation of Echinococcus canadensis (G7) in Mexico.

We evaluated the genetic variation of Echinococcus G7 strain in larval and adult stages using a fragment of the mitochondrial cox1 gen. Viscera of pigs, bovines, and sheep and fecal samples of dogs were inspected for cystic and canine echinococcosis, respectively; only pigs had hydatid cysts. Bayesian inferences grouped the sequences in an E. canadensis G7 cluster, suggesting that, in Mexico, this strain might be mainly present. Additionally, the population genetic and network analysis showed that E. canadensis in Mexico is very diverse and has probably been introduced several times from different sources. Finally, a scarce genetic differentiation between G6 (camel strain) and G7 (pig strain) populations was identified.

Gender as a factor of susceptibility to infection in experimental hydatidosis.

We developed an experimental model of hydatidosis in BALB/c mice with six groups, a group of females and another group of males was infected with PSC of Echinococcus, granulosus. Another two groups were gonadectomised and infected with PSC. and another two groups were healthy controls. They were all bled and sacrificed after sixteen weeks post-infection. The cysts in the abdominal cavity were count, and samples were taken from liver. A microscopic study was made of the tissue around the cyst to evaluate the chronic inflammatory response. In addition the seric levels of estradiol and testosterone by means of radioimmunoassay (RIA) were determined. The results were that the females presented a greater number of cysts in liver than the males, in addition the levels to estradiol almost rose to the double in males and females after 16 weeks post-infection, and the testosterone diminished. The granulomatous response around the cysts was greater in the females than in the males. The gonadectomization affected the susceptibility to the infection in females, diminishing in number of hepatic cysts found. One concluded that the females are more susceptible to the infection by metacestode of E. granulosrus, than the males. The female displayed one better granulomatous answer than the males. Nevertheless this was not sufficient to eliminate the parasite or to inhibit its growth. The levels of estradiol and testosterone undergo an imbalance, observing that estradiol increased in chronic stages of the infection whereas the testosterone diminishes, which would indicate to us that probably the parasite causes hormonal imbalance in chronic stages, to be able to remain by long periods in its host.

Echinococcus granulosus cattle strain identification in an autochthonous case of cystic echinococcosis in central Mexico.

Echinococcosis is a frequent hepatic parasitic disease in several countries but it is practically absent in Mexico. A cattle strain of Echinococcus granulosus was identified by RAPD, PCR-RFLP and mitochondrial CO1 gene analysis in an autochthonous case. The parasite was obtained after a laparoscopic excision of a liver cyst from a patient that was symptomatic for 6 years but mis-diagnosed before hospitalization.