Progress Report as of March 2002


Climate Variability and Human Health Impacts in Colombia

Colombian field studies of malaria are underway in Nuqui (Chocó Province) and El Bagre (Antioquia Province). Nuqui is situated on the Pacific coast. El Bagre lies on the flood plain of the Cauca river in northwestern Colombia.

Since June 2001, the team has been collecting epidemiological and entomological data. The entomological data comprise observations on adult mosquito vectors (mosquito biting rates, human landing collections, parity rates) and earlier developmental stages (larval density and physico-chemical variables at breeding places). The team also set up a weather station at each site to monitor daily cycles of air temperature, low temperature, high temperature, actual evapotranspiration, soil temperature, solar radiation, solar energy, degree-days, barometric pressure, wind speed, wind direction, wind chill, wind run, precipitation, humidity and dew point.

Laboratory studies found a strong effect of temperature on the gonotrophic cycle of mosquito vector Anopheles albimanus. For mosquitoes on their second cycle, the average duration of time from feeding until oviposition at 24°C was 86.5 hours, significantly longer than the average duration at 27°C (72.5 hours) and at 30°C (69.1 hours). 

A mathematical model of malaria transmission at Nuqui is under development for further testing and improvement. The aim is to understand entomological, epidemiological and climatic interactions. The latest version of the model reproduces monthly Plasmodium falciparum malaria incidence observed at Nuquí during the period 01/November/1997-28/February/1999. This period includes an outbreak of P. falciparum malaria and an El Niño event. In the model, the primary cause of the outbreak is an increase in temperature during the El Niño event.
The Geographical Information System for Malaria (SIGMA) is also under development on the JAVATM platform. This makes it accessible via Internet and compliant with different operating systems (Windows, Macintosh, Linux, Solaris or Unix). SIGMA includes databases of incidence, vector presence, and geographical risks at national, regional and local levels in Colombia.