Dengue Patients Treated with Doxycycline Showed Lower Mortality Associated to a Reduction in IL-6 and TNF Levels.

OBJECTIVE: To determine the effect of doxycycline treatment on cytokine levels, including tumor necrosis factor (TNF) and interleukin 6 (IL-6), and mortality in dengue patients at high risk of complication. METHODS: A group of dengue hemorrhagic fever patients (n=231) were randomized to receive either standard supportive care or supportive care in addition to oral doxycycline twice daily for 7 days. Dengue virus infection was confirmed by PCR using multiple primers. Serum samples were obtained at days 0, 3, 5 and 7 and tested for levels of TNF and IL-6. RESULTS: Doxycycline-treated group presented a 46% lower mortality than that observed in the untreated group (11.2% [13/116] vs 20.9% [24/115], respectively, p=0.05). Moreover, administration of doxycycline resulted in a significant (p<0.01) decrease in levels of TNF and IL-6 versus controls in the tests performed during follow-up (day 3, 5 and 7). Patients who died in both groups possessed significantly (p<0.01) higher levels of TNF and IL-6 compared to those who survived at all-time points. CONCLUSION: The above findings suggest that doxycycline can provide a clinical benefit to dengue patients at high risk of complications. This effect could be mediated by decreasing pro-inflammatory cytokine levels.

An assessment of the importance of subsurface catch basins for Aedes aegypti adult production during the dry season in a neighborhood of Merida, Mexico.

We compared the number of adult Aedes aegypti emerging from subsurface catch basins located in the streets against the number of pupae (as a proxy of adults emerging) from the entire container larval habitats found at residential premises within 1 ha of a neighborhood in the Mexican city of Merida during 8 days in the dry season of 2012. Aedes aegypti adults were collected from 60% of the subsurface catch basins. They produced 12 adults/day/ha (95% confidence interval [CI], 6.4 to 17.9), 5 females (95% CI, 2.1 to 7.7), and 7 males (95% CI, 3.8 to 10.7). In contrast, only 7 containers holding water were identified in 30 premises inspected, 1 bucket was positive for Ae. aegypti larvae, but no pupae-positive containers were found. No other mosquito species were found. This study revealed the importance of this type of nonresidential and subterranean aquatic habitat for Ae. aegypti adult production in this neighborhood of Merida during the dry season.

Entamoeba histolytica: oxygen resistance and virulence.

Entamoeba histolytica virulence has been attributed to several amoebic molecules such as adhesins, amoebapores and cysteine proteinases, but supporting evidence is either partial or indirect. In this work we compared several in vitro and in vivo features of both virulent E. histolytica (vEh) and non-virulent E. histolytica (nvEh) axenic HM-1 IMSS strains, such as complement resistance, proteinase activity, haemolytic, phagocytic and cytotoxic capacities, survival in mice caecum, and susceptibility to O(2). The only difference observed was a higher in vitro susceptibility of nvEh to O(2). The molecular mechanism of that difference was analyzed in both groups of amoebae after high O(2) exposure. vEh O(2) resistance correlated with: (i) higher O(2) reduction (O(2)(-) and H(2)O(2) production); (ii) increased H(2)O(2) resistance and thiol peroxidase activity, and (iii) reversible pyruvate: ferredoxin oxidoreductase (PFOR) inhibition. Despite the high level of carbonylated proteins in nvEh after O(2) exposure, membrane oxidation by reactive oxygen species was not observed. These results suggest that the virulent phenotype of E. histolytica is related to the greater ability to reduce O(2) and H(2)O(2) as well as PFOR reactivation, whereas nvEh undergoes irreversible PFOR inhibition resulting in metabolic failure and amoebic death.