The World Health Organization attributes the global surge in dengue cases to various factors including climate change, population growth, and increased global travel facilitating the spread of the virus. Rising temperatures and humidity due to climate change enhance mosquito breeding and the replication of the dengue virus.
“Currently, dengue is on the rise, with climate change being a significant factor contributing to the increased disease transmission. The most critical factors associated with dengue are temperature, rainfall, and relative humidity,” said Dr. Bayo Segun, WHO representative, during his presentation at the first Dengue Summit held in Manila last June.
The president of the Philippine Medicine Association (PMA), Dr. Hector Santos, underscored the potential rise in dengue cases in the coming months, attributing it to climate change and urging the public to be vigilant. He emphasized the need for collaboration among key stakeholders in strategically preparing to combat dengue.
“The rising number of dengue cases serves as a stark reminder of the urgent need for a unified front in the battle against this disease,” Santos stated, reaffirming the commitment to “Zero Dengue Death by 2030” in alignment with the United Nations’ Sustainable Development Goal 3.
Local dengue cases on the rise
From January 1 to July 27, 2024 dengue cases in the Philippines increased by 33% with 128,833 cases compared to the 97,211 recorded in the same period of last year. Meanwhile, number of deaths went down to 337 from 378 in 2023.2 The DOH continues to remind the public of the importance of sustained measures and interventions especially during the rainy season.
The heavy to intense rainfall caused by the recent habagat or the southwest monsoon enhanced by severe tropical storm Carina are early indicators of La Niña. According to the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) in early July, the 70% chance of La Niña occurring in August to October this year will trigger more rainfall in the country. Cooler conditions in the in the Central and Eastern Equatorial Pacific, complemented by the warmer temperatures in the Western Pacific close to the Philippines increase the likelihood of having more low-pressure areas or tropical cyclones.
How does the changing weather patterns affect the rise of dengue cases in the country? Increased rainfall can create more breeding sites for mosquitoes, while the warmer temperatures can accelerate mosquito life cycle and replication rate of the dengue virus.
In an interview with Dr. Anna Ong-Lim, infectious disease expert from the Philippine Foundation for Vaccination, she highlighted the critical role of climate factors among many others in driving dengue outbreaks. “The shifts in temperature can significantly influence the transmission of dengue. Given the persistent presence of dengue in our region, it is evident that climate change has the potential to intensify the transmission of the disease. Particularly concerning [is the impact of dengue among] children below the age of nine years, as they are more vulnerable to intensified transmission,” said Dr. Anna Ong-Lim, infectious disease expert from Philippine Foundation for Vaccination.
Medical communities urge for vaccine approval
During the inaugural Dengue Summit, health experts called on the Food and Drug Administration (FDA) to approve the second-generation vaccine against dengue as cases surge nationwide. This step is crucial in aligning with the UN Sustainable Development Goal of achieving zero dengue deaths by 2030.
“Vaccination reduces or eliminates the impact of variables dependent on behavior. Take COVID, for example. Prior to vaccination availability, preventive measures included mobility restrictions, mask-wearing, social distancing, and minimizing contact outside one’s household. Any lapses in adherence increased the risk of infection. However, with vaccines now available, community restrictions are largely lifted, offering built-in protection. The aim is to replicate this success with other infectious diseases. With vaccination, individuals can resume normal behaviors without fear of disease exposure,” Dr. Ong emphasized.
The DOH has been reminding the public on the “5S” strategy: search and destroy mosquito breeding sites; uphold self-protection, like using insect repellents; seek early consultation at the nearest health care facility; support fogging, spraying and misting in hot spot areas; and sustain hydration for symptom management in dengue infection.
In addition to this, Dr. Ong-Lim provided some practical tips to consider while the dengue vaccine is not yet available:
- Community-based interventions are crucial and more likely to succeed in controlling the virus-carrying mosquitoes.
- Preventing mosquito bites is essential to break the transmission cycle of dengue.
- Use of Mosquito nets is emphasized in many developing countries to limit transmission during sleeping hours.
- Avoidance behavior interventions are vital during the day to prevent mosquito bites.
- Proper water storage practices are crucial to prevent mosquito proliferation in communities.
Given the unpredictable weather patterns and mosquito behaviors, vaccination is highlighted as an important intervention for preventing severe cases of dengue infection, reducing dependence on behavioral measures.
Rain or shine, dengue remains a persistent threat to public health. As we navigate through changing weather patterns and environmental conditions, it is crucial to remain vigilant in our efforts to combat this disease. While measures such as vector control and personal protection are essential, the availability of a dengue vaccine can strengthen the integrated prevention and control strategy against this century-old threat.
