Open drains and garbage attract dengue spreading mosquitoes in Delhi slums

Dengue cases have been rising in India over the last few years and battling the rise in cases due to the dual effects of climate change and uncontrolled urbanisation has been challenging. While climate change has led to increasingly erratic monsoon patterns, warming, higher temparatures and humidity – all factors favourable for dengue spreading mosquitoes to thrive, haphazard urbanisation patterns, overcrowding and poor urban management have been adding fuel to fire. 

What is Dengue

Dengue is a mosquito-borne viral disease that spreads through the bite of an infected Aedes mosquito. The virus responsible for causing dengue, is called dengue virus (DENV). There are four strains of DENV virus, which increase the possibility of people being infected four times due to different strains of the virus. While many DENV infections produce only mild illness, some can cause an acute flu-like illness that can develop into a lethal complication, called severe dengue, which is a leading cause of serious illness and deaths in some Asian and Latin American countries.

The most common symptoms of dengue include fever with headaches, nausea, vomiting, rash, eye pain, muscle and joint pain, bone pain, swollen glands. Dengue stays for about 2 to 7 days. There is no specific medication to treat dengue.

The best preventive measure for dengue is to avoid mosquito bites through use of personal protective measures such as nets, mosquito repellent creams and most importantly taking measures to prevent mosquito breeding sites by avoiding indoor and outdoor collection of water in pans, pots, bottles, tyres etc that can breed mosquito eggs and larvae

A recent study titled 'Socio‑ecological predictors of dengue in high incidence area of Delhi, India' published in Nature, Scientific Reports from Delhi, where dengue has become a recurring monsoon bane looks at household and community level factors influencing dengue transmission in high-incidence areas of South West district of Delhi. The study collected information on dengue incidences within the last year and factors affecting them from 347 households from the South- West district of Delhi. 

The study found that:

Dengue presented a significant physical and economic burden on the affected

A wide range of symptoms were reported by people affected by dengue with majority reporting headaches, muscle/bone/joint pain, nausea/vomiting, eye pain, rashes, redness of eyes, weakness, and vertigo. Majority of the people sought active medical treatment with 26.2 percent spending less than 3000 Rs, 54.8 percent between 3000 and 10,000 Rs, and 19 percent surpassing 10,000 Rs for treatment.

Dengue was more common in poor socioeconomic settings  

Dengue cases were significantly higher in people from the lower economic group with income levels below 10,000 per month, houses with rudimentary material, without a separate kitchen and those using wood, kerosene, or other fuels.

Water supply, unhygienic surroundings, open drains led to more dengue infections

Houses having regular water supply had lower dengue cases as compared to those with irregular or intermittent water supply

Households having garbage collection sites within 200 m of their homes had a higher incidence of dengue

Type of drainage facilities were found to be significantly associated with dengue cases with

more cases of dengue in household with open drains

Similarly, the presence of construction sites within 500 m of the homes, living near a tertiary care hospital  was associated with more dengue cases perhaps because of unhygienic surroundings, lack of maintenance leading to accumulation of water that can favour mosquito breeding. Many of the households that had bamboo plants were found to have more dengue cases due to accumulation of water and moisture that helped in breeding of mosquitoes indoors. 

Knowledge, awareness and action helped reduce dengue cases

Some households practised various methods for maintaining cleanliness to prevent mosquito breeding such as cleaning drainage, eliminating standing water, and using insecticides in their surroundings. Some also used protective equipment such as mats, coils, bed nets, creams, and sprays to prevent being bitten by mosquitoes. 

Communities engaged in practice to remove mosquitoes by removing garbage/ cleaning, having insecticide application and cleaning drainage were less likely to report dengue cases compared to households in communities that did not follow these practices. The frequency with which communities practised cleaning and implemented preventive measures was found to be associated with decrease in dengue cases.  

While communities have a crucial role to play in preventing dengue, it is important that municipal bodies/urban area authorities play their part and set right the poor governance mechanisms that are slowly turning cities in India into hotbeds of diseases, filth and mismanagement.