Public Health Project Plays Part in Controlling Dengue Transmission in Vientiane Capital

A recent report by Save the Children showed a major reduction in dengue fever instances across Vientiane Capital, Laos, between 2022 and 2023.
FILE: young student looking at a cup of Wolbachia mosquitoes (photo: Save the Children)

A recent report by Save the Children signified a major reduction in dengue fever instances across Vientiane Capital, Laos, between 2022 and 2023.

According to the report released on 27 February, this notable decline may stem from the inception of the Wolbachia Project in 2023, a collaborative effort between the Ministry of Health, Save the Children, and the World Mosquito Program (WMP). The initiative involves the release of approximately 60,000 cups of Wolbachia mosquitoes—each cup containing 200 to 300 mosquitoes—into the villages of the Saysettha and Chanthabouly districts of Vientiane Capital from April to August last year.

Aedes aegypti mosquitoes carrying Wolbachia exhibit heightened immunity against various viruses transmitted by other breeds, including zika, and yellow fever. This resistance substantially diminishes a mosquito’s capacity to transmit diseases.

The yield of the pilot project has been successful in terms of releasing Wolbachia mosquito, yet the success may stem from this new initiative by witnessing a substantial decrease in dengue fever cases in Vientiane Capital. As per the dengue data provided by the Ministry of Health indicated around 6,500 cases between January and November 2023, compared to approximately 16,000 cases in 2022.

The initiative’s primary goal is for Wolbachia mosquitoes to breed with the local mosquito population until a significant portion of mosquitoes have the Wolbachia bacteria, resulting in a significant reduction in dengue cases.

Similar projects conducted elsewhere, such as the WMP Wolbachia project in Yogyakarta, Indonesia, have yielded promising outcomes. A randomized control trial published in 2021 demonstrated a 77 percent decrease in dengue incidence and an 86 percent decrease in dengue-related hospitalizations.

While it is premature to exclusively attribute the decline in dengue cases to the Wolbachia project, the Ministry of Health hailed its success in September last year, following the completion of its four-month operation. The project will evaluate the results of the Wolbachia establishment among the local mosquito population through the long-time monitoring which will be conducted by collecting mosquitoes in the targeted villages, forwarding samples to Australian research facilities for thorough analysis in the upcoming years.

Phoutmany Thammavong, the project manager, expressed optimism about the potential expansion of the Wolbachia project to more districts in Vientiane Capital or even to other provinces once all the necessary elements are in place.

The report also highlights the concerning number of dengue cases among children, who accounted for about 40 percent of dengue cases in Laos. Between January and November 2023, approximately 13,500 cases of dengue were reported in children under 18, out of a total of around 35,500 cases in Laos, according to the Laos Ministry of Health. Children are particularly vulnerable to dengue due to weaker immune systems and heightened exposure to mosquitoes outdoors

“Since we’re still in a dry season, there has been a significant rise in dengue fever cases,” she remarked, noting a concerning surge at the start of 2024 compared to the previous years.

The Center for Information and Education for Health reported 1,175 dengue cases in 2024 thus far.

Phetmany emphasized the importance of individuals taking proactive measures to protect themselves, such as eliminating stagnant water around their homes and workplaces. She also advised the use of mosquito repellent cream or spray as a preventive measure.

The implementation of the Wolbachia Bacteria Project in Vientiane Capital represents a significant stride in mitigating dengue fever cases in the region. Continued assessments and efforts will be instrumental in gauging the project’s enduring impact on public health, particularly among vulnerable demographics such as children.