Diffusion Model for Describing the Regional Spread of Huanglongbing from First-Reported Outbreaks and Basing an Area Wide Disease Management Strategy.

Huanglongbing (HLB), a recent worldwide spreading disease on citrus, was detected in July 2009 in Yucatan State of Mexico. The objective of this study was to evaluate the fit of diffusion and classic disease gradient models to large-scale HLB spatial data originated from initial foci to improve sampling, monitoring, and control strategies for Diaphorina citri, vector of Candidatus Liberibacter asiaticus (CLas), putative agent of HLB. Four transect routes were selected: Yuc-1, Yuc-2, QRoo-1, and QRoo-2, based on the directionality of the prevailing winds and foci location of HLB infected plants. In these routes, 35 sites, 5 to 20 km apart, were selected for monthly evaluation during a 12-month period. A 10-insect sample and disease incidence and severity of HLB, further confirmed by PCR, were assessed per site. Mexican lime was more vulnerable (67.5%) than sweet orange (14%). Also, leaf symptoms were mostly found with homogeneous distribution but rarely reaching 100% of the tree canopy during the 12-month period. The diffusion model provided the best fit among the family of time-gradient curves (r2 = 0.90 to 0.99) due to the flexibility of a three-parameter model. The gradients were well conformed to the model in a 25 to 82.6 km range, having the east-west direction the longest effect. Yuc-2 and QRoo-2 transects showed 82.6 and 43.9 km gradients with a diffusion coefficient (Do) of 0.15 and 0.09, respectively. This study constitutes the first quantitative evidence of the regional spread of CLas from a single focus and the application of a flexible model that improved the fit and allowed to better compare different gradients. These results are useful to determine the size of Regional Areas of Diaphorina citri Control (ARCO), a management program currently implemented in Mexico to combat HLB.

[Benzodiazepines in the treatment of schizophrenia: a review]. / Las benzodiacepinas en el tratamiento de la esquizofrenia: una revisión.

Since the introduction of benzodiacepines in the medical practice their use has been generalized to numerous clinical situations. One of them is schizophrenia. In this article we analize the main settings for its use and the possible mechanisms of action, trying to draw some recomendations applicable to the psychiatric practice.

Effect of human gamma interferon on yellow fever virus infection.

We studied yellow fever virus infection in two species of monkey: Saimiri sciureus (squirrel monkeys) and Macaca mulatta (rhesus monkeys). Human gamma interferon was administered intravenously in five equal doses, one was given 24 hr before infection followed by four doses 24 hr apart. Interferon reduced the levels and duration of viremia and the severity of hepatitis in squirrel monkeys. Interferon prolonged survival time and delayed the appearance of viremia and hepatitis in infected rhesus monkeys, but it did not change overall mortality.