Seropositivity for Trypanosoma cruzi and Leishmania mexicana in dogs from a metropolitan region of Central Mexico.

Trypanosoma cruzi and Leishmania mexicana are parasites of humans and other mammals, causing American Trypanosomiasis and Cutaneous Leishmaniasis, respectively. Domestic dogs are considered key hosts for these parasites in the domicile and peridomicile cycles of transmission, due to their abundance and contact with human population. In Mexico, there are few studies that involve the study of infection with these parasites in dogs, and have only been carried out mainly in the endemic areas for these diseases. In the state of Querétaro (Mexico), infections with both parasites have been reported for dogs only from rural areas, with no records for the metropolitan zone. We analyzed the seropositivity to T. cruzi and L. mexicana in dogs from localities within of the metropolitan zone of Querétaro City in order to determine if these animals are exposed to these parasites and thus, could be an important part of the transmission cycle of these trypanosomatids in a densely populated urban region within the state of Querétaro, Mexico. Serum samples were collected from 303 dogs housed in the Animal Control centers of the municipalities of Querétaro and El Marques, analyzed by indirect ELISA and Western Blot using as an antigen the Iron Superoxide Dismutase (FeSODe) of the parasites. From the total serum samples, we detected 10.2% of seropositivity for T. cruzi and 2.9% for L. mexicana. Our results represent the first evidence of infection with T. cruzi in domestic dogs from the Metropolitan Zone of Querétaro, and the first record for L. mexicana in Central Mexico. Ongoing investigations seek to confirm the circulation of these parasites in the area to evaluate the risk associated to the human population.

Biological parameters of the triatomine, Meccus phyllosomus pallidipennis, fed on two bloodmeal sources under laboratory conditions.

Chagas disease is one of the most important vector-borne diseases in Latin America, including Mexico. Meccus phyllosomus pallidipennis (Stål), 1872 (Hemiptera: Reduviidae) is a Mexican triatomine vector that is commonly associated with hens and rabbits. The biological parameters of two cohorts fed on hens (H) and on rabbits (R) were evaluated. The median lifecycles of the two cohorts were 198 days (H) and 180 days (R). Moreover, mortality was around 30% in both cohorts. Time lapse for beginning of feeding was 0.5-1.9 (H) and 1.1-2.4 min (R). Feeding times of each instar in both cohorts were over 10 min. Most specimens fed on hens defecated immediately after feeding, whereas those that fed on rabbits defecated within 1-5 min post-feeding. Similar numbers of males and females (50%) were obtained in both cohorts. An average of 2.1-2.3 eggs per female per day was noted in both cohorts, with eclosion rates of 95.4 (H) and 88.8% (R). Thus, it can be concluded that M. phyllosomus pallidipennis may take advantage of feeding in hens, as in rabbits, which could imply a higher risk of Trypanosoma cruzi transmission to humans and animals in its distribution area.

Chronic administration of thiamine pyrophosphate decreases age-related histological atrophic testicular changes and improves sexual behavior in male Wistar rats.

Aging is a multifactorial universal process and constitutes the most important risk factor for chronic-degenerative diseases. Although it is a natural process, pathological aging arises when these changes occur quickly and the body is not able to adapt. This is often associated with the generation of reactive oxygen species (ROS), inflammation, and a decrease in the endogenous antioxidant systems, constituting a physiopathological state commonly found in chronic-degenerative diseases. At the testicular level, aging is associated with tissue atrophy, decreased steroidogenesis and spermatogenesis, and sexual behavior disorders. This situation, in addition to the elevated generation of ROS in the testicular steroidogenesis, provides a critical cellular environment causing oxidative damage at diverse cellular levels. To assess the effects of a reduction in the levels of ROS, thiamine pyrophosphate (TPP) was chronically administered in senile Wistar rats. TPP causes an activation of intermediate metabolism routes, enhancing cellular respiration and decreasing the generation of ROS. Our results show an overall decrease of atrophic histological changes linked to aging, with higher levels of serum testosterone, sexual activity, and an increase in the levels of endogenous antioxidant enzymes in TPP-treated animals. These results suggest that TPP chronic administration decreases the progression of age-related atrophic changes by improving the intermediate metabolism, and by increasing the levels of antioxidant enzymes.