Genetic Control of Mosquitoes: population suppression strategies

Over the last two decades, morbidity and mortality from malaria and dengue fever among other pathogens are an increasing Public Health problem. The increase in the geographic distribution of vectors is accompanied by the emergence of viruses and diseases in new areas. There are insufficient specific therapeutic drugs available and there are no reliable vaccines for malaria or dengue, although some progress has been achieved, there is still a long way between its development and actual field use. Most mosquito control measures have failed to achieve their goals, mostly because of the mosquito's great reproductive capacity and genomic flexibility. Chemical control is increasingly restricted due to potential human toxicity, mortality in no target organisms, insecticide resistance, and other environmental impacts. Other strategies for mosquito control are desperately needed. The Sterile Insect Technique (SIT) is a species-specific and environmentally benign method for insect population suppression, it is based on mass rearing, radiation mediated sterilization, and release of a large number of male insects. Releasing of Insects carrying a dominant lethal gene (RIDL) offers a solution to many of the drawbacks of traditional SIT that have limited its application in mosquitoes while maintaining its environmentally friendly and species-specific utility. The self-limiting nature of sterile mosquitoes tends to make the issues related to field use of these somewhat less challenging than for self-spreading systems characteristic of population replacement strategies. They also are closer to field use, so might be appropriate to consider first. The prospect of genetic control methods against mosquito vectored human diseases is rapidly becoming a reality, many decisions will need to be made on a national, regional and international level regarding the biosafety, social, cultural and ethical aspects of the use and deployment of these vector control methods.

Seroprevalence and sociocultural conditionants of Chagas disease in school aged children of marginal zones of Asunción

Chagas disease is becoming a public health problem in Latin America due to the wide distribution, the high prevalence, the magnitude of the damage caused and the difficulties to control it. In Paraguay, the disease is mainly distributed in the departments of Paraguari, Cordillera and Central. Prevalence in marginal zones, where migrations from rural populations and endemic areas make possible the urbanization of the disease, has no been studied yet. This is a descriptive study with a cross-sectional sampling and a probabilistic system recruitment carried out in school aged children from marginal zones of Asuncion to determine the prevalence of Chagas' disease. Serological methods, parasite isolation and questionnaires were used to achieve the goals. Nine hundred and fifty three children were studied to determine the prevalence of Chagas' disease in marginal zones which was 1.4%.

Factors of poor prognosis of visceral leishmaniasis among children under 12 years of age. A retrospective monocentric study in Belo Horizonte, State of Minas Gerais, Brazil, 2001-2005

INTRODUTION: A major concern with the visceral leishmaniasis (VL) is its high lethality rate, even with proper treatment. Low age, prior malnutrition, disease duration prior to diagnosis, severe anemia, fever for more than 60 days, diarrhea and jaundice are known poor prognostic factors. The goals of this study are to describe the clinical and laboratory characteristics of VL among children under 12 years of age and to identify the factors associated with VL poor outcome. METHODS: Two hundred and fifty children under 12 years of age with confirmed VL admitted to Hospital João Paulo II (FHEMIG), Belo Horizonte, Brazil, between January 2001 and December 2005 were evaluated retrospectively. The primary outcome was the poor clinical evolution: sepsis, and/or pneumonia, and/or urinary tract infection, and/or of bleeding (expect epistaxis), and/or severe neutropenia (neutrophil < 500 cells/mm3). Odds ratio (crude and adjusted) and its 95% confidence interval for each variable were calculated. Values less than 0.05 were considered significant. RESULTS: Average age was 3.3 years (3.6 months-11.6 years), 71.2% were younger than 5 years and 47.2% lived in Metropolitan Area of Belo Horizonte. The mean fatality rate was 3.6%. Sixty-six (26.4%) patients presented poor evolution. After a multivariate analysis, age <18 months, abnormal respiratory physical examination on hospital admission, and platelets <85,000/mm3 remained associated with increased chance of poor evolution. CONCLUSIONS: The results suggest that patients aged between 12 and 18 months, with platelet counts bellow 85,000/mm3, and respiratory abnormalities at admission should be considered potentially severe.

Inflammatory bowel diseases: principles of nutritional therapy

Inflammatory Bowel Diseases - ulcerative colitis and Crohn's disease- are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Total parenteral nutrition has been used to correct and to prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission in adults and promoting growth in children. Due to its low complication rate and lower costs, enteral nutrition should be preferred over total parenteral nutrition whenever possible. Both present equal effectiveness in primary therapy for remission of active Crohn's disease. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted, especially in patients presumed to need total parenteral nutrition. Recent research has focused on the use of nutrients as primary treatment agents. Immunonutrition is an important therapeutic alternative in the management of inflammatory bowel diseases, modulating the inflammation and changing the eicosanoid synthesis profile. However, beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these and other nutrients (glutamine, short-chain fatty acids, antioxidants) still need further evaluation through prospective and randomized trials.