Status report on Dengue outbreak in India: From cases to what are states doing to control it, all you need to know

Dengue cases in Delhi have jumped to over 2,700, with a three-year-old girl haven succumbed to the disease, taking the total fatalities due to the disease reported in Delhi this year to nine.

This is the highest number of fatalities due to dengue recorded in a year in the national capital since 2017 when the cumulative death count officially reported was 10.

The Union health ministry last week sent teams of experts to nine states and union territories, which are reporting a high number of dengue cases, to support them in public health measures for control and management of the disease.

This is in accordance with the directions issued by Union Health Minister Mansukh Mandaviya during a review meeting on the dengue situation in Delhi on Monday, a health ministry statement said.

Mandaviya had directed the ministry to extend help to states and union territories that have a high incidence of dengue cases, the statement said.

The statement said that a significantly higher number of cases in some states have been reported in October as compared to the number of cases during the same period in the previous year. It said that 1,16,991 dengue cases have been reported by states and union territories across the country.

Fifteen states and union territories are reporting their maximum cases in the current year. These states have contributed to 86 percent of the country's total dengue cases till 31 October, it stated.

Here is a deep dive into the possible reasons for the outbreak, what tests should be done and how it can be controlled.

What is Dengue?

Dengue fever is an extremely common vector-borne disease in India, spread through the mosquito bite of the daytime feeder, Aedes aegypti. Thousands of people are affected every year in India, especially during the monsoons.

Currently, there is no direct cure or vaccination for dengue fever but one’s condition can be improved and cured through a combination of medical and home treatment.

Dengue causes a wide spectrum of diseases. This can range from subclinical disease (people may not know they are even infected) to severe flu-like symptoms in those infected. Although less common, some people develop severe dengue, which can be any number of complications associated with severe bleeding, organ impairment and/or plasma leakage. Severe dengue has a higher risk of death when not managed appropriately.

Which season does it spread the most?

As per India’s National Centre for Disease Control (NCDC), dengue outbreaks “are most likely to occur in post-monsoon period when the breeding of the mosquitoes is highest".

Waterlogging in the monsoons is a perfect breeding condition for mosquitos, thus increasing the risk of its spread that becomes even higher in areas with hygiene issues. Every year in India, from July to November, an upsurge in cases of dengue has been observed.

How does it spread?

NCDC notes that mosquitoes “generally acquire the virus while feeding on the blood of an infected person" and, after an incubation period that lasts between 8-10 days, an infected mosquito can spread the virus to people for the rest of its life.

Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature, relative humidity and unplanned rapid urbanization.

Dengue virus is transmitted through the bite of a female Aedes (Ae.) mosquito. Aedes is a daytime feeder and can fly up to a limited distance of 400 meters. Dengue mosquitoes can’t breed once the temperature falls below 16 degrees.

Humans are the main host of the virus, although monkeys have been found to pick up the infection in some parts of the world.

How to prevent dengue

Prevention can be done by maintaining neat and clean surroundings, by cleaning blocked drains, avoiding waterlogging, emptying stagnant water bodies (water accumulated in old tyres, pots and pans, coolers, small puddles at construction sites), keeping water tanks and containers tightly covered, pouring oil over the water sources, the introduction of larva eating fish into the water bodies to reduce mosquito breeding

Many health departments have used guppy fish to check the spread of mosquito-borne diseases. They are bred in the same manner as mosquitofish. “Guppy drives” have been carried out in Tamil Nadu, West Bengal and Gujarat, while Gambusia have been used by civic administrations in Punjab’s Mohali and Amritsar and Haryana’s Panchkula, along with capital Chandigarh.

Bred in ponds, wells and smaller water bodies, these fish are known to check the spread of mosquito-borne diseases like malaria and dengue. Here are the advantages of these fish:

• These fishes are self-perpetuating after their establishment and continue to reduce mosquito larvae for a long time.
• The cost of introducing larvivorous fish is relatively lower than that of chemical control.
• The use of fish is an environmentally friendly method of control.
• Larvivorous fish such as Gambusia and Poecilia prefer shallow water where mosquito larvae also breed.

What are states doing to prevent its further spread?

According to data available with the NVBDCP, more than 60,000 dengue cases were reported till September this year by the states and UTs with 30 deaths. In 2020, the country had seen more than 44,000 cases of dengue and 56 deaths due to the disease.

In Delhi, amid the spike in cases of dengue, the three civic bodies have intensified their fogging and spraying drives.

In Punjab, the government is providing free testing/treatment of dengue in government hospitals. Indian Express reports that the rate of Elisa test to confirm dengue have been capped in private hospitals, test kits have been procured, breeding checkers have been enhanced.

Fifteen states and union territories are reporting their maximum cases in the current year. These states have contributed to 86 per cent of the country's total dengue cases till 31 October. These nine states and Union Territories are Haryana, Kerala, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, Uttarakhand, Delhi and Jammu and Kashmir.

In view of this, central teams, comprising experts from the NVBDCP, National Centre for Disease Control (NCDC) and Regional Offices, have been sent to the nine states and union territories that have reported more cases in October compared to September, the statement said.

The teams are tasked to assist and support these states and union territories to mount an effective public health response. They have been asked to report on the status of vector control, availability of kits and medicines, early detection, availability and use of insecticides, status of anti-larval and anti-adult vector control measures, among others.

They will also brief state health authorities about their observations.

With inputs from agencies