How others control dengue
In 2010, Kolkata city had faced its worst dengue outbreak -- an event that prompted the municipality to draw up a definitive plan to control the menace.
"We started to get positive results from next year for both dengue and malaria," Debashish Bishwas, chief vector control officer of Kolkata Municipal Corporation, told The Daily Star.
The plan involved dividing 206.2-square km of Kolkata Municipality areas into 144 wards and 16 boroughs and bringing the whole system under the leadership of five vector management experts, three of whom are PhD holders in this field.
The authorities also formed 32 rapid action teams that took immediate steps after getting information about a dengue patient. Moreover, 1,700 field workers as well as 1,440 staffers work to create ward-based data banks and its monitoring and also do awareness campaigns and collect information about fever.
This year, the Kolkata municipality has had about 500 cases of dengue and no confirmed death. In 2022, two people died and about 5,000 were infected.
Kolkata's dengue management work begins in January with scoping out all possible breeding sources.
Besides, there is a ward-based database containing coordinates of ponds, high-rise buildings, open spaces, water tanks, drums, wells, vacant land, small drains and under-construction buildings.
When a field level worker gets information about a possible dengue patient, they ask the patient to give their blood sample to the Urban Primary Health Care (UPHC) found in every ward.
A patient can easily get their report through mobile SMS and the report goes to several places including chief vector control officer, chief health officer and deputy mayor when it is positive.
The Rapid Action Team visits the house of the dengue patient within 24 hours to conduct extensive search to find out Aedes mosquito larvae, eggs or breeding sources there. The team also conducts extensive searches of at least 50 adjoining houses, he said.
"None of the dengue patients remain out of our list as we also collect data from all other private diagnostic centres by our workforces," he said.
These activities are done before the start of the rainy season in July or August.
Kolkata has banned fogging for about five years now as it is not an effective method: it drives out mosquitoes from one place to another.
"To control Aedes or other mosquitoes, round-the-year activities is a must," he said, adding that fine for finding aedes larvae goes up to Rs 1 lakh.
Malaysia, on the other hand, uses an integrated vector management to control dengue.
Those include year-round strategy source reduction, targeted larval control, community involvement, and the implementation of the Wolbachia method to suppress dengue transmission through Aedes mosquitoes.
Medical professionals and hospitals are required by law to report dengue cases to the government upon detection, while specialized teams conduct robust anti-mosquito efforts within a 200-meter radius of identified cases, said Hasan Mohammad Al-Amin, a researcher on Bangladeshi Mosquitos at the QIMR Berghofer Medical Research Institute in Australia's Queensland.
In Thailand, the Thai government employs a comprehensive approach to managing dengue like Malaysia.
Their year-round programme includes active surveillance, vector control through larviciding and fogging, community engagement, education campaigns and innovative methods like the Wolbachia bacteria approach to reduce mosquito-borne diseases.
Indonesia is also deploying the Wolbachia method.
The Indonesian Health Ministry on June 6 released modified (Wolbachia-infected) mosquitoes in Semarang, Central Java, on a pilot basis, and plans to expand it to other cities, according to The Jakarta Post.
"Controlling the dengue outbreak requires a combination of methods; community engagement is essential for success," Alamin said.