Taenia solium: Socioeconomic changes and prevalence evolution in four endemic communities in northwestern Mexico.

In Mexico, for the past 30 years, a continuous decrease in the incidence of clinical taeniosis/cysticercosis has been documented. This work aimed to determine the influence of improvement in socioeconomic conditions on the prevalence of Taenia solium in four endemic communities in northwestern Mexico. This study was carried out in two phases. First, documentary information (1989-2018) was collected about the prevalence of Theridion solium in the federal entity of Sinaloa State. Second, a pilot study was performed in four communities of Sinaloa, which had an endemic history of Taenia transmission. In each community, a risk factor questionnaire was applied, and serum and stool samples were collected for convenience in a non-probabilistic way. Anti-cysticercus antibodies and adult worm coproantigen were determined. The documentary analysis showed the incidence of taeniosis and cysticercosis to have decreased by 98 and 53%, respectively, while the human development index increased by 5% (1992-2017). Our data suggest that the risk of parasitic transmission is low, although female sex was a risk factor for reporting tremors or seizures (prevalence rate 2.1336, CI: 1.1821-3.8508) and background of tapeworm infection (prevalence rate 1.2893, CI: 0.9795-1.6972). No tapeworms or eggs were found while examining stool samples, but protozoa cysts were observed in four samples. Unexpectedly, only one of the 79 stool samples was positive for coproantigens. This positive result was confirmed in a second sample. However, the evaluation of a third sample was negative. No antibodies were found in human (n = 377) or pig (n = 69) samples. These data suggest parasite transmission has been interrupted and could be possibly associated with improving socioeconomic conditions. Further studies are needed to determine the real prevalence of zoonoses in Mexico.

Genetic Polymorphisms of Tumor Necrosis Factor Alpha and Susceptibility to Dengue Virus Infection in a Mexican Population.

To evaluate the association of the -308 and -238 tumor necrosis factor alpha (TNF-α) gene polymorphisms with clinical manifestations of dengue and TNF-α serum levels in a northwestern Mexican population. The study populations included dengue fever (DF) and dengue hemorrhagic fever (DHF) patients, and a group of healthy controls (HCs) without history of dengue. Polymerase chain reaction-restriction fragment length polymorphism and Enzyme-Linked Immunosorbent Assay were performed to determine genotypes and serum concentration of TNF-α, respectively. There were no significant differences in alleles, genotypes, and haplotype frequencies between patients and HCs. However, when patients were separated into DF and DHF, there was an increased prevalence of the -308 GA genotype in HCs compared to DHF (odds ratio [OR] = 0.129, 95% confidence interval [CI] = 0.018-0.945, p = 0.025), as well as the GG haplotype (OR = 0.49, 95% CI = 0.273-0.880, p = 0.01757) in DF. The genotypes of both polymorphisms were not associated with hematologic manifestations. Serum TNF-α levels were significantly higher in patients than in HCs (p = 0.004). Our results suggest a minimal effect of the -308 and -238 TNF-α gene polymorphisms in dengue patients and that their increased serum levels of TNF-α are independent of genotypes.