Dengue? Kerala rubber farms feel the sting

Instead of the Aedes Aegypti, traditional dengue vector, Aedes Albopictus or the Asian Tiger Mosquito is the main carrier in the state.

The mosquitoes, says Dr B K Tyagi, the director of the ICMR centre, breed in the coconut shells/plastic cups that collect latex from rubber trees. According to the study, 79.7 per cent breeding occurred in these shells or cups.

Aedes Albopictus also breed in cocoa pods in the Western Ghats, though only two percent.

The mosquito maintains two peaks of high density correlating with the two monsoon seasons. “There is a direct correlation between preponderance of Aedes Albopictus and conflagration of dengue cases in Kerala,’’ says Tyagi.

The Western Ghats range, rife with rubber plantations, is said to be the epicentre of the disease in the state.

The mosquito has spread from its abode in the forest to human settlements along the coastal region. Among the Aedes species present in the state, Aedes Albopictus constituted 70 percent of the mosquito population, while the traditional dengue mosquito showed only 4.4 percent presence.

“The human factor has obviously played an important role in dispersing the mosquito species from the forest to cities. When it was in the forest, the mosquito was benign but now it is the only vector transmitting the disease,’’ says Tyagi. “Whether the same vector is responsible for chikungunya spread is also being investigated. The report is expected in 15 days. However, looking at the trends in other parts of the world, there seems to be a great possibility,’’ he says.

Chikungunya returned to the state after 32 years.

Kerala originally had a total cropped area of over 2 million hectares, with paddy as the major crop covering about 35 per cent of the area. By 1975, the paddy fields reduced to 30 per cent with only 0.881million hectares. In 2003, the area shrank to just 0.31 million hectares.

Kerala reported 1,023 cases of dengue in 2005, with 8 deaths. There was a major outbreak in 2003 with 3,546 cases and 68 deaths. This year, there have been 894 cases with five deaths. There also has been 65,667 suspected chikungunya cases so far.