Moderately-high temperatures hasten the larval stage of mosquitoes leading to smaller mosquitoes which require more frequent blood meals, increasing the probability of spread of dengue - Dr. Sam Rawlins, CAREC, 11th Annual Research Conference, Faculty of Medical Science.
SLAP! ANOTHER mosquito bite. Wonder if this is a dengue-carrying mosquito ? That wouldn't be far-fetched; researchers at the Caribbean Epidemiology Centre (CAREC), the regional research centre based in Trinidad and Tobago, are very concerned about an increase of dengue in the region, spread by the Aedes aegypti mosquito.
Dr. Sam Rawlins of CAREC, who was a presenter at the recently-held Faculty of Medical Sciences, 11th Annual Research Conference, said that the disease seemed to be under control between 1980 to 1991 but since then there appears to have been a tremendous increase in its incidence. CAREC has rounded up an interdisciplinary research team that includes an atmospheric physicist. One of the possibilities which they are exploring is a link between climate change and the supply of mosquitoes. The prospective study will demonstrate the association of temperature, rainfall, and climate change generally to dengue incidence in the Caribbean and the dominance of this linkage in comparison to other linkages.
Dr. Rawlins said that they are investigating what has changed and whether there are new factors impacting the increase in dengue fever.
He said that Trinidad and Tobago's Ministry of Health had reported about 20 deaths last year from dengue haemorrhagic fever. Jamaica reported 29 cases last year but only 14 of them were laboratory confirmed. The last outbreak occurred here in 1998 with 1509 reported cases.
Looking at the climate change/disease link, Dr. Rawlins said that with El Nino there were some bumps (in the disease) in 1982, 1986, but in El Nino plus one, there were really high numbers of cases. Then there were periods of droughts and he said people were storing water in open containers breeding habitats for mosquitoes. In rainy times, there are pools of water, more breeding habitats for mosquitoes.
"People have to store water but tyres are the greatest producers of Aedes aegypti and this has to change. Why do we tolerate so much garbage in the 21-member countries?" Dr. Rawlins asked.
In fact, stating that Jamaica is due another big epidemic, Dr. Rawlins said that he would like the region to take the whole dengue fever spread a little more seriously.
"Twenty deaths in Trinidad translate to about 4,000 deaths in the U.S. Yet we are taking on the West Nile virus," he said.
Besides the garbage, drought, and rainfall, temperature is another significant factor in the climate change/dengue fever link. Dr. Rawlins said that the temperatures are on the increase and higher temperatures increase the amount of feeding by the mosquitoes and the probability of dengue transmission to new hosts.
Moderately high temperatures hasten the larval stage of mosquitoes, leading to smaller mosquitoes which require more frequent blood meals, increasing the probability of spread of dengue. Increases in climatic temperature, therefore increases the dengue fever risk.
Dr. Rawlins said that climate change could affect diseases such as vector-borne diseases - malaria (why is the region seeing the condition in people who have not travelled, he asked); food and waterborne diseases when the temperature increases; respiratory diseases; heart-related stress diseases and skin diseases.
