The war against mosquitoes saves lives and money in Sri Lanka

A large-scale campaign against mosquitoes in Sri Lanka has helped reduce the incidence of dengue fever and save a lot of money, according to a study conducted by the University of Global Public New York Health.

Dengue fever is a mosquito-borne viral disease that results in fever, body aches, rashes, and sometimes life-threatening complications. In such cases, hospitalization and intensive care are mandatory, which increases public health spending in areas heavily affected by dengue fever, such as South Asia.

The disease has plagued Sri Lanka in recent years with more than 55,000 reported in 2016. Initially, efforts were made to develop a dengue vaccine to reduce the incidence of the disease. However, adverse effects badociated with the vaccine prevented its widespread deployment. This has directed prevention efforts towards controlling the mosquito population.

To this end, Sri Lanka has launched a public health partnership initiative to reduce mosquito populations through a team effort between the Ministry of Health, the Armed Forces and the police.

The focus has been on door-to-door monitoring over large areas to detect and eradicate mosquito breeding sites. Each team included public health personnel, as well as representatives of the police and the army. Every day, at least 50 sites were inspected, with the team looking for stagnant water in containers and other likely locations. This was in addition to existing mosquito control measures, such as the application of larvicides and insecticides.

Current research examined the impact of the intervention between June 2014 and December 2016. The area chosen for research was an urban part of western Sri Lanka with a high endemic dengue fever. The parameters examined included symptomatic dengue rates before and after the intervention and the cost of the program, as well as the cost-benefit badysis. Confounding factors, such as climate change, have been adjusted by badyzing the data.

The purpose of the study was to provide a source of information to public health planners and policy makers to identify the interventions that produced the greatest positive impact at the lowest cost, particularly in regions and cultures where resources were limited.

The study concluded that the mosquito control program had an impact on mosquito breeding in the target population, reducing the number of larvae, as well as a 57% decrease in dengue rate. This means that the intervention conducted for 31 months has prevented nearly 2,200 dengue cases.

The total cost of the mosquito population control initiative was $ 271,615. Of this amount, approximately 90% was used to pay the costs of staff employed in the program. This is not surprising, as the intervention relied entirely on door-to-door visits and inspections and the manual removal of all areas where mosquitoes were likely to breed.

But was it a cost-effective way to do it? To find out, the researchers determined the costs in three possible situations, depending on the number of dengue cases requiring hospitalization. In the first case, moderate hospitalization was considered, ie 50% of dengue cases. In the second case, a low hospitalization was planned at 25%. The third situation was high hospitalization rates, at 75%.

In the context of moderate hospitalization, the financial savings resulting from reducing the number of dengue cases through the mosquito control initiative amounted to $ 291,990. This more than offset the costs of the program, leaving a surplus of $ 20,247. In addition, the researchers estimated that 176 disability-adjusted life years (DALYs) had been avoided during the study, saving $ 98 for each DALY.

When considering a high hospitalization scenario, the program was also cost-effective in this context, saving $ 512 per DALY. But with the low hospitalization scenario, a set of calculations led to it being considered profitable, but not the others.

"Even if a safe dengue vaccine becomes available in the future, mosquito control is likely to remain an essential complementary strategy to limit the spread and intensification of dengue," said author Yesim Tozan. main.

In conclusion, mosquito control efforts could bring significant benefits if carried out with careful planning, resolution and vigor.

Lead author, Prasad Liyanage, said, "Our study suggests that dengue-affected communities can benefit from investments in mosquito control if interventions are implemented in a rigorous and coordinated fashion between sectors. In doing so, it is possible to reduce the disease and the economic burden of dengue fever. "

The study was published in the journal Lancet Global Health in May 2019.