Medio ambiente y protozoosis sistémicas. I. Variabilidad climática y su incidencia en la malaria.

Source: OAI


La malaria sigue siendo la enfermedad tropical infecciosa parasitaria más importante en Venezuela, afectando zonas rurales de los estados Bolívar, Sucre y Amazonas, entre otros. Recientemente se ha estudiado la importancia de la variabilidad climática y su incidencia en la enfermedad, lo cual se relaciona a distintos elementos climáticos que impactan en la biología del vector y en la transmisión. En el marco de los cambios globales, el fenómeno El Niño-Oscilación del Sur (ENSO) se ha visto asociado a brotes epidémicos de la enfermedad. En el presente artículo se revisan los aspectos más importantes de esta relación entre un componente del medio ambiente (clima) y tan importante protozoosis sistémica, como lo es la malaria.,, Nivel monográfico

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    ABSTRACT: Malaria epidemics in African highlands cause serious morbidity and mortality and are being reported more frequently. Weather is likely to play an important role in initiating epidemics but limited analysis of the association between weather conditions and epidemic transmission parameters has been undertaken. We measured entomological variables before and during an epidemic of malaria (which began in February 1998) in a highland region of south-western Uganda and analysed temporal variation in weather data against malaria incidence (estimated from clinic records), mosquito density and entomological inoculation rates (EIR). Indoor resting density of Anopheles gambiae s.l. was positively correlated with malaria incidence (r = 0·68, P < 0·05) despite extremely low vector densities. EIR totalled only 0·41 infectious bites per person during the entire 8-month study period. Rainfall during and following the El Niño event in 1997 was much higher than normal, and rainfall anomaly (difference from the mean) was positively correlated with vector density 1 month later (r = 0·55, P < 0·05). Heavier than normal rainfall associated with El Niño may have initiated the epidemic; the relationship between temperature and transmission parameters remains to be defined. The results from this study indicate that, in this highland population, epidemic malaria may occur at extremely low inoculation rates.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 09/1999; 93(5):480-7. DOI:10.1016/S0035-9203(99)90344-9 · 1.84 Impact Factor
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    ABSTRACT: B a ck g ro u n d : Malaria is a tropical infectious disease related to a complex group of biological, social and ecological factors with a wide-range of variation according to time and space. Recently, research has focused on the entomological as well as the epidemiological impact of climatic variation on malaria dynamics. For these reasons a non-conventional epidemiological study was created to evaluate the impact of climatic variation on malaria dynamics in a northeastern region of Venezuela (Sucre State, 1986-2000). The etiological agent of malaria in this region is Plasmodium vivax. Methods: Malaria case records were retrieved for an epidemiological study for 15 years and this was correlated to climatic variation according to NOAA records for Venezuela in the same period to determine if climatic variation has a real impact on malaria dynamics. Results: For a studied period 64,803 cases of malaria were reported (annual mean: 1,117±951 cases) with five relevant peaks (1988 [1,512 cases], 1990 [2,071 cases], 1991 [4,165 cases], 1997 [3,513 cases] and 2000 [5,011 cases]). We found a significant correlation (r2>0.50, P<0.05) between the increase of malaria cases and La Nina phenomena (defined for Venezuela as a cold and wet period) in some years of the studied period. Those years with non-significant correlation between malaria and weather were explained by socio-economical and political factors (failure in control policies, people mobilization as well fails in treatment). Discussion: Changes in climatic patterns certainly impact on biology and ecology of malaria vector in Sucre State (Anopheles aquasalis), explained in part in life cycle shortening due to temperature, precipitation and wet (water stage), as well as better life expectancy (earth stage) (adult phase). Then, vector population increases and this jointly with other biological and social factors prone to malaria cases increase, which was clearly observed in the present report. Granted by IAI(YRP)(Program CRN).
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    ABSTRACT: Malaria has been increasing globally, and epidemics tend to occur when weather conditions favor this vector-borne disease. Long-term meteorologic forecasting using El Niño Southern Oscillation (ENSO) may assist in anticipating epidemics and targeting scarce resources. To determine whether malaria epidemics in Venezuela are related to ENSO and rainfall and to determine whether such a relationship could be used to predict outbreaks. Retrospective analysis of national malaria morbidity (1975-1995) and mortality (1910-1935) data in the coastal zone and interior of Venezuela in relation to El Niño events and rainfall. Correlation between malaria mortality and morbidity and sea surface temperatures (SSTs) in the Eastern Tropical Pacific, a parameter of ENSO. Malaria mortality and morbidity have increased by an average of 36.5% (95% confidence interval, 3.7%-69.3%; P=.004) in years following recognized El Niño events. A moderate correlation was found between Pacific tropical SST during a Niño event and malaria 1 year later (r=0.50, P<.001). Malaria mortality is more strongly related to drought in the year preceding outbreaks than to rainfall during epidemic years. Historic and recent data from Venezuela demonstrate that malaria increases by an average of about one third in the year following a Nino event; change in malaria risk can be predicted from Pacific SSTs in the previous year. Therefore, the occurrence of an El Niño event may help predict malaria epidemics in this part of South America.
    JAMA The Journal of the American Medical Association 01/1998; 278(21):1772-4. DOI:10.1001/jama.278.21.1772 · 35.29 Impact Factor
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