Preventive drugs could play a role in dengue control, say experts

Study shows they could be more effective than vector control methods in certain instances

Preventive drugs have been found to be effective in controlling the spread of malaria, and experts now say they may be needed to fight dengue outbreaks as well.

Coupled with the use of data science to predict large clusters, they could help to combat the Aedes aegypti mosquito threat in Singapore, said Professor Martin Hibberd from the London School Of Hygiene and Tropical Medicine.

"We've seen that malaria drugs have been effective in preventing the spread of the disease in Haiti.

"Given that the dengue drug uses the same mechanism, it should also be applicable for controlling dengue outbreaks," said Prof Hibberd.

The infectious diseases expert was in Singapore, where he spoke at the 5th Asia Dengue Summit held at Orchard Hotel last Wednesday.

The United States' Centres for Disease Control and Prevention lists two preventive drugs, or prophylactics, that travellers could take to prevent malaria.

"This approach of taking preventive medication - in the case of malaria - is currently dispensed to travellers but is not one that has been used in Singapore, where mosquitoes and dengue are found endemically.

"As controlling the chain of dengue transmission within a household or community is highly time-sensitive, using these prophylactics could help extend that timeframe, especially since several days often pass before people present symptoms of dengue infection," added Prof Hibberd.

A study by researchers from the London School Of Hygiene and Tropical Medicine, using datasets from Singapore, suggested preventive medication could play a role in dengue control.

The scientists, whose paper was published last year, said that when applied in areas that have recently experienced cases of disease, prophylactic drugs could be more effective than adult mosquito-killing vector control methods.

They could even offer the possibility of interrupting individual chains of transmission if rapidly deployed.

Researchers in Singapore are currently conducting clinical trials on a drug made by Belgian drug manufacturer Janssen Pharmaceuticals.

The new experimental drug works by preventing two proteins from the dengue virus - known as NS3 and NS4B - from interacting, similar to the mechanism used by malaria drugs.

Singapore is currently in the middle of a huge dengue wave, with more than 15,000 cases reported in the first 24 weeks of this year.

Professor Leo Yee Sin, executive director at the National Centre for Infectious Diseases, said the current approach on dengue management in Singapore focuses on community awareness, and seeking early medical attention to achieve early diagnosis.

While there is a Dengvaxia vaccine for dengue, it is approved for use in patients aged 12 to 45 who have previously contracted dengue, said Prof Leo.

Prof Hibberd said that in addition to preventive medication, it is also possible to use predictive data models such as the one developed by the National Environment Agency's (NEA) Environmental Health Institute and the NUS Saw Swee Hock School of Public Health to pre-empt outbreaks.

The model can predict dengue case trends up to three months ahead.

Aside from data science, NEA also uses a network of gravitraps - designed to attract and trap female Aedes adult mosquitoes that are looking for sites to lay their eggs in - to provide surveillance of mosquito populations.

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A version of this article appeared in the print edition of The Straits Times on June 20, 2022, with the headline Preventive drugs could play a role in dengue control, say experts. Subscribe