On May 25, the Centre informed the Delhi High Court that to reduce breeding of aedes mosquitoes, solid waste must be “properly” disposed during non-transmission season of the infection (December to May).
To which the Delhi High Court replied, “This is an aspect which local authorities — including the municipal corporations as well as the central government — have not even begun to examine.” But all that the civic bodies need to do is take a look at 7,000-odd houses in the endemic zone of West Delhi.
In 2015, the capital recorded the worst dengue outbreak — 15,867 people tested positive for the disease while 60 deaths were reported. Even as the dengue wave gripped the capital, these 7,000 houses recorded zero dengue cases during the entire season. With Delhi facing the possibility of yet another outbreak for the third year in a row, these houses had executed what government authorities failed to do — control breeding of the aedes mosquito throughout the year.
In 2012-2014, the research wing of the Indian Council for Medical Research (ICMR) — National Institute of Malaria Research (NIMR) — conducted a pilot study on 20 localities under the South corporation’s West zone to see if controlling mosquito breeding kept vector-borne diseases in check.
The West zone had stood third in the number of dengue cases reported, and these 20 localities had reported maximum cases.
The study revealed that the aedes mosquito breeds throughout the year — both in transmission (June-November) and non-transmission season (December-May). It also showed that during transmission season, vector breeding spreads from key containers — overhead tanks and water storage — to secondary containers such as cemented tanks, coolers and mud pots.
But the most alarming finding was that maximum breeding takes place in solid waste — breaking the myth that the aedes mosquito breeds only in clean water.
“Initial findings in 2012 showed that maximum breeding took place in overhead tanks. During the monsoon, breeding increased by 40 per cent. We then completely removed the larvae from the overhead tanks. The result was reflected in 2013. While breeding increased by 40 per cent in other zones of west Delhi, it increased only by 2 per cent in this zone. The same year, only two cases were recorded from the 7,000 houses in the zone,” said Dr Bhupender Nath Nagpal, scientist, World Health Organisation, and the principal investigator of the study. (see box)
“In 2015, when Delhi recorded the maximum dengue cases, no case was reported from the 7,000 houses. This proved that one needs to undertake breeding control measures throughout the year,” Dr Nagpal said.
In 2013, the municipal corporations accepted the findings of the report. The then health minister had directed the municipal health officer to ensure that domestic breeding checkers (DBCs) continue house checks throughout the year.
However, on the ground, the findings of the report gathered dust. Last year, Dr Nagpal approached the AAP-led Delhi government and requested it to conduct a similar survey across the capital. Before submitting a fresh proposal, Dr Nagpal identified 15 localities with maximum dengue cases over the last four years using geographic information system (GIS).
“In April last year, I presented the proposal to the health minister and health secretary, Delhi government. I was told that the government would fund the second leg of the study… Every time I enquire about the proposal, I am told that it is under process. Now, the entire season has gone and there has been no word from the government yet,” Dr Nagpal said.
Delhi Health Minister Satyendar Jain did not respond to calls or texts. “As far as the Delhi government is concerned, our action plan for vector-borne diseases is carried out throughout the year,” Dr S M Raheja (Additional Director General-Waterborne Diseases Control), Directorate General of Health Services, Delhi government, said.
The way ahead
A visit to the DDA flats in Bindapur shows how the fight against vector-borne infections was taken up. Pointing to a cement tank outside one of the houses, Arshad Shamim, senior research fellow, NIMR, said, “We had destroyed 150 of these in the first week. These were the main culprits.”
“We then took up a large advocacy initiative. As the owners were barely home, we decided to train the domestic help who worked at the flats, as they know exactly where water is stored — from pots to refrigerators. We told them that no clean water should be stored openly or kept uncovered. This made a difference,” Shamim added.
Pointing out that the entire study was carried out in coordination with MCD officials, he said, “The study showed how the MCD has to work in tandem with the community. It also displayed how advocacy and community mobilisation is the key in controlling vector-borne diseases.”
Before the project was undertaken, Dr Nagpal held a training programme on surveillance for MCD workers. “Meetings were organised with councillors, RWAs, schools and trade unions. A large-scale advocacy initiative was undertaken before surveillance, so that residents become important stakeholders in the project,” Dr Nagpal said.
During the entire study, a total of 1,408 unused containers of water were emptied and scrubbed to kill the attached eggs. About 185 overhead tanks having broken lids were also covered with cloth.
“Additionally, 1 mg/l temefos granules was put into 1,213 containers of drinking water, in accordance with WHO recommendations. Overhead tanks and water storage containers were identified as the key source of breeding during transmission and non-transmission seasons. After the first round of surveillance, the 7,000 houses — covering approximately 35,000 people — were surveyed on a fortnightly basis in collaboration with the MCD,” Dr Nagpal added.