By Jahangir Alam, Hasib Raman, Napoleon Manegdeg, Nilo Manangan
Four Asian cities supported by the Urban Climate Change Resilience Trust Fund (UCCRTF) reported severe dengue outbreaks from January to September 2019. Reports from the health departments and medical institutions in La Trinidad and Malay, Philippines and in Faridpur and Patuakhali, Bangladesh showed an increase in the number of dengue patients in the period compared to the same period last year. Increased prevalence of dengue fever is linked to climate change due to increased rainfall, which leads to more standing water that provides favorable conditions for mosquitos to breed.
In total, 451 dengue cases were reported in La Trinidad, 338 dengue cases in Malay, 2,795 dengue cases in Faridpur, and 587 dengue cases in Patuakhali. The disease caused 20 deaths in the Philippine province of Aklan (where the municipality of Malay is located), two in Faridpur, and the death of an eight-year old boy in La Trinidad and a nineteen-year old girl in Patuakhali.
Flooding increasingly threatens the health of people living in UCCRTF cities. Along with the direct losses, damage, and inconvenience caused by perennial flooding, most flood-prone cities experience associated health risks such as diarrhoea, leptospirosis, and dengue, among others.
The link between dengue and the presence of water in the environment is well documented. The dengue carrying mosquitoes breed profusely in any place where clean standing water is present such as in ponds, creeks, canals, water tanks, containers, and flower pots. Dengue cases rise sharply during the rainy season and after flood events as there is more stagnant water in cities.
The main underlying cause of dengue outbreak in the four UCCRTF cities this year is the spike in mosquito population, which can be traced from increased number of mosquito habitats especially in frequently flooded and waterlogged communities in La Trinidad, Malay, Faridpur, and Patuakhali. A dengue larval survey in La Trinidad revealed the widespread presence of dengue carrier mosquito larvae in water bodies throughout the municipality.
Continuous rain in Faridpur in August 2019 has inundated several parts of the city leading to waterlogging in low-lying areas, which in turn has caused outbreaks of water and vector-borne diseases including dengue. Since dengue is linked to precipitation, flooding, and poor drainage, there might be an increase in seasonal dengue outbreaks with changing precipitation patterns in many parts of the world, if not properly addressed.
With no effective cure or preventive vaccine for the dengue virus, efforts to contain the disease focus on reducing the number of mosquitos and protecting people from bites. There is a need for dengue-prone communities to maintain cleanliness and remove stagnant water, especially during the rainy season and after flooding, to prevent mosquitoes from breeding. As such, addressing flooding and flood risks and ensuring the environment is clean are priority resilience initiatives in the four UCCRTF cities:
- In La Trinidad, UCCRTF is working with the community to improve the flood control system along Balili River by expanding the volume capacity of the flood culvert. This is to improve flood flow and reduce perennial flooding in the adjacent strawberry fields.
- Malay being a coastal town has numerous swampland areas which are ideal breeding grounds for dengue mosquitoes. The pilot community is evaluating the flood dynamics from which the team will implement nature-based solutions and green infrastructure in strategic portions of the main river. This will help reduce water runoff, decrease erosion of riverbanks, and reduce incidents of flooding and flash floods in the area.
- In Faridpur, the sustainable river project along a small section of the Padma River will improve drainage and flood flow and reduce waterlogging in the pilot community.
- Patuakhali is one of the most flood prone cities in Bangladesh due to its location and low-lying elevation. The pilot community in Patuakhali is implementing a community-based solid waste management program that will improve environmental waste pollution and at the same time reduce waterlogging and clogging of drainage in the community.
Local government in the cities have supported the work of the community-led projects. For instance, the Provincial Health Office in La Trinidad has strengthened measures to check breeding sites of mosquitoes. “The flood control project will contribute to dengue control as it will reduce the presence of stagnant waters on the ground and help eliminate breeding sites of dengue-causing mosquitoes,” said Vicente P. Perez, Jr., municipal planning and development officer of La Trinidad, Benguet. “Lessening flooding would prevent creation of breeding sites,” he stressed.
The La Trinidad Municipal Health Office encourages upland communities to practice a “4S” strategy for disease control:
- Search and destroy mosquito breeding sites;
- Self-protective measures of using mosquito repellent and wearing long sleeves;
- Say yes to fogging; and
- Seek early consultation when signs of the disease appear.
Building resilience is not limited to providing solutions to a single issue but creates spaces for co-benefits and more holistic change. The four cities have identified various flood mitigation measures as their priority community-led projects. These projects will build resilience against flooding. The overlap between flood mitigation, waste management, and health is clear as flood mitigation will reduce the build-up of stagnant waters left behind after floodwaters recede.