North Kerala prone to chikungunya

The northern districts of the State need to be vigilant against chikungunya outbreak during the monsoon, says a top-level team of scientists from the Indian Council of Medical Research (ICMR).The team, which recently conducted a study in chikungunya-affected areas of Kasaragod, finds a strong possibility of people of central Kerala, where chikungunya struck last year, becoming immune to the disease.N. Arunachalam, Deputy Director of the Centre for Research in Medical Entomology of the ICMR, Madurai, told The Hindu that chikungunya had only one serotype (a serologically distinguishable strain of a micro-organism) and the patient developed immunity against the disease-causing virus after one attack. As the northern part of the State escaped an outbreak last time, he said, people there are prone now.

Detailed study

The eight-member team, including Dr. Arunachalam, conducted a detailed study for four days at Panathoor, Panathady and Kinanoor Karinthalam panchayat areas where chikungunya had been reported. The team left for Madurai on Tuesday. On its findings, he said the situation was under control at present, but the disease could reappear once the monsoon started. The mosquito density in the area was low and the sanitation and awareness programmes of the Health Department were effective.

Heavy rain blamed

He said the heavy rain during the summer had led to the outbreak in these villages. The prima facie evidence suggested that Aedes albopictus mosquitoes were the carriers of the virus in Kasaragod unlike in Alappuzha and Pathanamthitta districts where Aedes aegypti were the vectors. The team had collected samples of mosquitoes and would conduct studies. M. Muniraj, team members and Senior Research Officer of ICMR, Madurai, said the Aedes aegypti mosquitoes were daytime biters and, therefore, mosquito repellents and nets and fogging were not of much use in fending them off. Only their breeding could be controlled and the public should be made aware of the measures needed.Dr. Arunachalam said the Aedes albopictus mosquitoes spread chikungunya mostly in rural areas. They bred in all types of containers left open with freshwater. The mosquito larvae were found even in village wells.

How it reaches villages

On the reasons for the occurrence of chikungunya in rural areas which were cleaner than urban areas, Philip Samuel, Research Scientist at the ICMR, Madurai, said many houses in villages, especially in the plantation sector, were closed and containers with water were left open inside and on the premises.Dr. Samuel said the local bodies should identify such houses and contact their owners to make them destroy such breeding spots. Steps needed to be taken to let fish that fed on the larvae into the wells.Dr. Arunachalam said the team would visit the area during the monsoon for more studies. The awareness programmes needed to be continued.

The Hindu, May 21, 2008