A recent survey conducted by the vector control unit in Kerala’s Ernakulam district shows that chances of mosquito-borne diseases like dengue are high in some parts.
The survey report indicates that densities of larvae of Aedes Egypti mosquitoes, which cause dengue fever, are high mainly in Kochi corporation limits.
In the survey which measured the density of mosquito larvae at 46 places within city limits, it was found that ‘House Index’ of Aedes mosquitoes was 11 in Konthuruthy. It is a densely populated residential area located at the heart of Kochi city.
According to the World Health Organisation (WHO) guidelines, House Index is the percentage of houses infested with larvae and/or pupae of mosquitoes. The survey results are a matter of concern as a House Index of over 10 indicates high chances of an epidemic.
Only the places that have a House Index level of one or less are considered safe with little possibility of dengue outbreak.
Meanwhile, District Medical Officer, Dr N K Kuttapan tells TNM that though the survey was still underway in coastal areas of the district, chances of outbreak were high in these places also. “People in coastal areas who face issues of water shortage in summer, usually store and keep water. As Aedes mosquitoes lay eggs in stagnant fresh water, there are high chances that the disease could spread in these areas,” Dr Kuttapan says.
The data released by the district vector control unit holds much importance as it points out that many commercially important places in the city were also facing the threat of dengue outbreak.
Breteau Index of Aedes mosquitoes, the number of positive sources per 100 houses inspected, in regions like Ponnekkara, Palarivattom, Karanakkodam and Kaloor North, was found to be at 10. According to the report, the chances of dengue occurring are less only if the Breteau index is under five. If it’s between 5 and 50, there are moderate chances of dengue outbreak.
Palarivattom and Kaloor are two of the significant areas in the city with many commercial establishments, including major hospitals working in the area.
The presence of Culex mosquitoes that spread Japan fever was also found in corporation (division 69) at Thrikkanaravattam and Semetherimukku.
Mosquito hour density (MHD), the number of Culex mosquitoes found at a place in 10 hours, was reported to be 100 during the survey at Nasrath Corporation Colony (division 26) and Thevara Pandit Karuppana library (division 59). These results are also a matter of concern as MHD levels above 80 signify high chances of disease outbreak.
Mitigation Measures
The district health department has already initiated measures to control the possibility of outbreak of mosquito-borne diseases. Measures are being taken to destroy larvae and source of propagation.
Spraying to destroy larval growth in open stagnant water and fogging to kill adult mosquitoes are ongoing in various parts of the city. According to officials, it is the presence of breeding grounds that has increased the density of mosquitoes.
“If the department gets good cooperation from residents, we can bring things under control. Those who store water should make it a point that they cover it properly. Since that is drinking water, no spraying can be done there. So it is important to cover the water which is collected and stored,” said Dr Kuttapan.
Health department officials told TNM that plantation areas in districts like Kothamangalam do not have a threat of mosquito-borne diseases as of now.
Mitigation measures are being carried out in city limits with the help of health wing of Kochi Corporation and in association with panchayats in rural areas of the district.
District health department also conducted an awareness programme at Maharaja’s College in Kochi for prevention of mosquito-borne diseases.