Nha Trang leaders on Friday said they support a plan to release mosquitoes infected with a strain of bacteria in the resort beach town next year to control dengue and Zika. The plan was introduced by a Health Ministry working group at a meeting with local leaders, following a successful pilot project carried out in Nha Trang between 2013 and 2015.
Aedes aegypti mosquitoes carrying Wolbachia bacteria have been released since April 2013 on Tri Nguyen Island in Khanh Hoa Province. Tran Nhu Duong, deputy director of the National Institute of Hygiene and Epidemiology, said that after three months, 70-80 percent of Aedes aegypti mosquitoes on the island carry the bacteria.
Scientists have officially confirmed the ability of these mosquitoes to block the Zika virus and prevent it from being transmitted to humans,according to Le Tan Phung, deputy director of Khanh Hoa Health Department.
The method takes advantage of the naturally occurring strain of bacteria known as Wolbachia, which live in insect cells and are found in 60 percent of common insects. Infecting mosquitoes with Wolbachia significantly reduced their ability to transmit dengue and the Zika virus, studies have shown.
The bacteria has been released in several countries including Australia, Brazil, and Indonesia as part of strategies to control dengue. In the pilot project in Vietnam, it helped almost eradicate dengue cases in Tri Nguyen, an island 2 km off Nha Trang coast.
In the meeting Friday, Nguyen Dac Tai, vice chairman of Nha Trang's People's Committee, said local leaders support the plan. However, he insisted that it be carried out discreetly.
Health officials said the infected mosquitoes would be released in four wards of Nha Trang. Vietnam has so far reported three Zika patients, including one in Nha Trang.
Aedes aegypti mosquitoes are the main vector of both dengue fever and the Zika virus, but they naturally do not carry Wolbachia bacteria. But the ability will be inherited, making more mosquitoes unable to transmit the virus. In April 2013, scientists handed over a total of 8,000 mosquito larvae injected with Wolbachia bacteria to nearly 800 families to breed on the island.
On February 1, the World Health Organization (WHO) declared the Zika outbreak an international health emergency. It cited a "strongly suspected" relationship between Zika infection in pregnancy to microcephaly, a condition marked by abnormally small head size in babies that can result in developmental problems.