Preventing Dengue in Sri Lanka

9 July 2019, Colombo, Sri Lanka. It is important to take preventive action to eliminate mosquito breeding sites and protect against mosquito bites to prevent dengue.

During the past few months, an increased trend in the number of dengue cases have been reported in Sri Lanka. From January to June 2019, Epidemiology Unit of the Ministry of Health, Nutrition and Indigenous Medicine reported 25,216 dengue cases. An increased number of cases have been reported from Colombo and Gampaha Districts.

The vector for dengue, Aedes mosquito, bites during the day. The highest biting intensity is about two hours after sunrise and before sunset. The infected Aedes mosquito bites 4-5 people at a time which results in multiple dengue cases in the same area. An infected person, may or may not have symptoms of dengue, but will be a source of dengue virus for uninfected mosquitoes. Patients infected with the dengue virus can spread the infection (for 4–5 days; maximum 12 days) via Aedes mosquitoes after their first symptoms appear.

Aedes mosquito lays eggs in stagnant water which can survive up to one year. The eggs can withstand dry conditions and hatch when water is available. Therefore, it is vital to keep neighborhoods clean and free of receptacles that attract the dengue carrying mosquitos. Water storage tanks, flower pots and vases, garden fountains, bird baths, fridge trays, water dispenser trays, broken cisterns, discarded bottles, tins, discarded tyres, coconut shells etc are all possible sites for mosquitoes to breed. As the eggs can survive up to one year in dry containers, they should be scrubbed clean at least once a week.

In addition to vector control measures, people can prevent mosquito bites by taking personal protection measures:

• Wearing clothes that cover the body and minimizes exposure to mosquito bites;
• Mosquito repellents;
• Mosquito nets;
• Installing net screens on doors and windows.

Dengue is characterized by a high fever (40°C/104°F), accompanied by two or more of the following symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea and vomiting and rash on skin. Symptoms usually appear 4-10 days after the bite of an infected mosquito, and last for 2-7 days. It is advised that people experiencing dengue symptoms should rest, consume plenty of fluids and take paracetamol to bring down the fever. If the situation worsens, it is vital to get admitted to a hospital as soon as possible.

Severe dengue, or dengue haemorrhagic fever (DHF), can be deadly due to severe bleeding, plasma leaking, fluid accumulation, or organ impairment. Warning signs occur 3–7 days after the first symptoms along with a decrease in temperature (below 38°C/100°F) and include severe abdominal pain, persistent vomiting, rapid breathing, bleeding gums, fatigue, restlessness and blood in vomit. Complications from dengue fever and DHF are preventable with early identification and proper medical management.

World Health Organization is working closely with the Ministry of Health Nutrition and Indigenous Medicine to control the spread of dengue, by specifically collaborating in reviewing dengue control and prevention activities at district and national level, enhancing dengue surveillance with GIS based mapping and training health care workers on the latest dengue case management and prevention guidelines.