DEHIWALA, SRI LANKA — For G. Samantha Fernando, a list of dengue patients is a map of where to check for disease-carrying mosquitoes and their larvae.
This tropical island experiences seasonal rains which fill parched riverbeds. The rivers, swollen with rainwater, flow into irrigated rice fields, enabling another season of farming.
But the rains also bring pockets of water that become mosquito breeding grounds. This year, 320 people died of dengue between January and August in a severe outbreak of the disease. About 45 percent of the 140,000 people who were diagnosed with the illness live in Colombo, Sri Lanka’s largest city.
Fernando is a disease control assistant with the Medical Officer of the Health in Dehiwala, a Colombo suburb. Usually, he conducts investigations related to communicable diseases including leprosy, tuberculosis, avian flu and other illnesses. These days, however, most of his time is dedicated to helping control the dengue outbreak – a task that involves entering and examining people’s living quarters.
“Not everyone is welcoming,” Fernando says. “Some houses we visit refuse to open their gates to us or verbally abuse us.”
Manori Wijesekera, GPJ Sri Lanka
When Fernando sees the names and addresses of the four people admitted to hospitals the previous day, he and a colleague set out to visit their homes and neighborhoods.
Fernando’s team inspects houses and gardens, looking for potential mosquito breeding sites. In one place, the pair finds mosquito larvae in an open can half-filled with rainwater. The homeowner is given a red notice – a warning that action must be taken – and told that inspectors would return to ensure that the problem has been cleaned up.
It’s a serious endeavor: In March the Ministry of Health, Nutrition and Indigenous Medicine enacted the Declaration on the Control of Dengue for the Western Province, which has the highest number of dengue patients in the country. People who don’t comply can be fined up to 25,000 Sri Lankan rupees ($163), sent to prison for six months or both.
The inspection teams act quickly. The ministry created an online management system for 75 locations at state, private and military hospitals, where patient data is uploaded in real time to a central database. The system alerts a local ministry office when someone in that area is diagnosed with a communicable disease.
Starting this year, the inspection teams also hold special inspection days a few times each month in which multiple teams visit every house and inspect all properties in areas designated as a high risk for dengue, says K. C. R. Kaushalya, one of seven public-health inspectors at the Dehiwala health ministry office.
“The quick information-sharing has helped us to identify mosquito breeding areas very effectively,” he says. “We would have seen double or triple the number of dengue patients, if this system of monitoring and follow-up was not in place.”
The outbreak’s formal status as an epidemic has been removed, but health officials are readying for monsoon season to begin in September in the Northern and Eastern provinces, where they expect another wave of patients with dengue fever.
Manori Wijesekera, GPJ Sri Lanka
In the Western Province, nearly 1.7 million sites were visited from January to July by these teams, according to data from the National Dengue Control Program. These include homes, schools, private offices, government offices, factories, construction sites, religious places and others. On special campaign days, the teams are accompanied by local police and defense officers.
“The participation of the police and the security forces has really enhanced these inspections,” Kaushalya says. “People take it more seriously when they see a policeman or an Air Force officer.”
Globally, more than 2.5 billion people – more than 40 percent of the world’s population – are at risk of contracting dengue, according to the World Health Organization. Between 50 million and 100 million dengue infections occur every year, the WHO estimates. About 22,000 people die every year – mostly children.
Dengue infections have been endemic in Sri Lanka since the mid-1960s, with the first reported dengue fever case confirmed in 1962. Dengue infections peak during Sri Lanka’s two rainy seasons, from June to July and from October to December. An average of roughly 42,000 people contracted dengue in Sri Lanka each year between 2012 and 2016, although that number dropped to fewer than 30,000 in 2015. The number of deaths each year is not disclosed by health officials.
The last major dengue epidemic in Sri Lanka was in 2009, when more than 35,000 cases and 346 deaths were reported. That outbreak was considered an epidemic because of the high number of deaths. This year’s outbreak is taken equally as seriously because of the high number of total cases. The number of dengue patients in the current epidemic is nearly four times as many as in 2009, but the fatality rate has dropped to 0.22 percent.
Careful management of critical patients – in special dengue wards or by special medical teams – and early detection of the virus have contributed to the drop in the death rate, says Dr. LakKumar Fernando, clinical head of the Center for Clinical Management of Dengue & Dengue Hemorrhagic Fever. The center is the first specialized dengue treatment ward in the country for both adults and children.
Ranjani De Silva, a 57-year-old primary school teacher from Kattuwa, a suburb of Negombo, located about 38 kilometers (24 miles) north of Colombo, was hospitalized for dengue treatment in late July.
After two days of treatment in a general ward, she was moved to the center after she was diagnosed with impending dengue shock.
“I don’t think I would have survived if I didn’t take the blood test, or if this special ward was not here,” De Silva says, referring to a dengue antigen test she took after two days of feeling unwell. “I try not to think about what would have happened if I didn’t get treatment on time.”
Manori Wijesekera, GPJ Sri Lanka
Modern treatment is saving lives, LakKumar Fernando says.
“About 10 years ago, dengue was flagged as a deadly disease; it only led to death,” he says. “As a result, even medical staff accepted death as inevitable in patients with dengue hemorrhagic fever. We had to work to change that mindset as part of our clinical management.”
The 2009 epidemic spurred changes in controlling mosquito breeding grounds, too.
A Presidential Task Force on Dengue Eradication was created in May 2010 to bring together officials from the ministries of health, defense, environment and education, as well as from provincial councils and local government offices.
“This was the first time that different government agencies came together to combat a disease,” says Dr. Hasitha Tissera, head of the National Dengue Control Program at the Ministry of Health, Nutrition and Indigenous Medicine who is tasked with coordinating among the various agencies. “The agencies came together at both national and local government level – that was crucial to its effectiveness.”
Those agencies launched public awareness campaigns, including seminars focused on mosquito breeding prevention, during that period.
But the nature of dengue is changing.
For example, a key public message about dengue is that mosquitoes breed only in freshwater. That’s no longer true, says Faseeha Noordeen, a microbiology professor at the University of Peradeniya’s Faculty of Medicine who has done extensive research on dengue.
“Research has shown that mosquitoes now breed well in brackish water, so the public needs to know that adding salt to stagnant water pools in their premises won’t prevent mosquito breeding,” Noordeen says.
Another big change is that dengue no longer primarily occurs in urban or semi-urban areas. It’s now found in rural areas, too, including building sites, garbage dumps and anywhere else that can trap even small amounts of water, Noordeen says.
“Dengue is no longer a problem of city dwellers, and as people infected with dengue move around the country, they will transmit the disease to any mosquito which bites them and carries the infection to new areas,” she says.
Public-awareness campaigns should focus more on preventing not only mosquito breeding, but also mosquito bites, LakKumar Fernando says.
“The increased number of infected mosquitoes is what is causing the epidemic to spread,” he says. “If we can reduce mosquitoes biting, then we can reduce the spread of the infection. If each person guards himself against mosquito bites, the transmission speeds we see now will decrease dramatically.”
There’s also a new emphasis on dengue vaccination. Sri Lanka is part of a clinical trial for a vaccine being developed by Takeda Pharmaceutical, a Japanese drug manufacturer. The trial, which began in September 2016, covers eight dengue-endemic countries around the world and involves more than 20,000 children between four and 16 years old. About 2,100 Sri Lankan children have been vaccinated, LakKumar Fernando says.
It could take years before a fully functional vaccine is available for use against dengue, says Tissera of the National Dengue Control Program. In the meantime, dengue will continue to be a threat.
“We can never eradicate mosquitoes, but if we keep working together as we have in the past few months, we can beat this epidemic,” Tissera says.
Manori Wijesekera, GPJ, translated three interviews from Sinhala.