Mosquitoes laying eggs that remain dormant until the next rainy season can lead to a resurgence of diseases, presenting a continuous cycle of infections
As Tamil Nadu and Andhra Pradesh grapple with the aftermath of heavy rains and subsequent floods caused by the intensified cyclonic storm Michaung, a silent menace awaits in the form of mosquito-borne diseases.
The inundation of low-lying areas has not only submerged the city but has also created breeding grounds for mosquitoes, setting the stage for potential health crises.
Mosquitoes, notorious carriers of diseases such as dengue and malaria, find ideal conditions for breeding in the aftermath of heavy rains. The increase in humidity and a drop in temperature create a perfect environment for these vectors, particularly the Aedes mosquitoes, to thrive.
What many may not realise is that the breeding cycle of mosquitoes persists even after the rainy season due to the resilience of desiccated eggs that can survive for up to one and a half years without water.
Containers of all kinds, from tree holes to discarded tyres, become potential breeding grounds for these disease-carrying insects. Rains also form innumerable pools that become havens for continuous mosquito breeding.
Even well-intentioned efforts to cover containers with plastic can inadvertently contribute to the problem, as the stagnant water collected on the covers becomes a breeding site after just 10 days.
One significant concern is the potential spread of diseases through multiple modes of transmission. Beyond the conventional method of larvae hatching in standing water, trans-ovarian transmission poses an additional threat.
Infected mosquitoes laying eggs that remain dormant until the next rainy season can lead to a resurgence of diseases, presenting a continuous cycle of infections.
The global struggle against mosquito-borne diseases is evident even in well-managed regions like Singapore, where dengue remains a challenge to control, let alone eliminate. Unprecedented floods in July 2022 in Pakistan that displaced 33 million people serve as a stark reminder of the post-rainfall epidemics that can arise.
After the floodwaters receded, stagnant water in small containers became breeding sites for mosquitoes, resulting in widespread outbreaks of malaria and dengue. Malaria cases recorded a five-fold increase in 2023 compared with 2022. There is a shift in the malaria vector.
In Tamil Nadu and Andhra Pradesh, where floods are now a reality, the possibility of a dengue outbreak looms large. The alteration in rainfall patterns and the occurrence of cloud bursts contribute to the challenges faced by public health officials.
While heavy rainfall may flush out mosquito larvae from breeding sites, the stagnation in small containers creates ideal conditions for the exponential growth of mosquito populations, particularly the Aedes mosquitoes responsible for dengue transmission.
Post-flood preparedness becomes paramount in mitigating the risk of mosquito-borne diseases. The drying out of stagnated water, along with public awareness and precautionary measures, can play a crucial role in preventing outbreaks.
However, the challenge is not confined to the flood-affected regions alone. Even in areas unaffected by floods, the habit of storing water in and around households provides ample opportunities for mosquitoes to breed.
The complexity of the issue is further compounded by the potential coexistence of multiple mosquito vectors in the same breeding sources. In a scenario akin to Pakistan’s experience, a single water container may host both dengue-carrying Aedes mosquitoes and malaria-carrying Anopheles stephensi mosquitoes responsible for malaria transmission. This convergence of vectors increases the likelihood of individuals facing a double threat of contracting both diseases simultaneously.
As we witness shifts in climate patterns and the frequency of extreme weather events, it is imperative that communities and authorities alike remain vigilant in their efforts to combat the consequences of heavy rainfall.
In the face of escalating cyclones intensified by greenhouse effects, the United States for example, has experienced devastating impacts, prompting the government to engage in substantial debates and allocate substantial budgets for mitigation efforts. Mitigating the adverse impacts of climate change-induced cyclones necessitates concerted efforts.
Exploring the inevitability of disease outbreaks, particularly in the aftermath of cyclones, reveals a disconcerting correlation between these natural disasters and the subsequent surge in mosquito-borne diseases.
Compelling statistics highlight this unsettling trend, indicating that in nine out of 10 instances of global cyclones, a mosquito-related disease outbreak, often featuring fatal illnesses like dengue, ensues.
The gravity of the situation becomes even more apparent when considering the alarming number of deaths caused by dengue, further emphasising the urgent need for effective intervention.
Traditional approaches, such as commonplace mosquito repellants and coils, though offering momentary relief, merely “shut out” the problem without addressing the fundamental issue — the unrelenting cycle of mosquito breeding.
This stark reality underscores the pressing necessity for a paradigm shift toward innovative, sustainable and green devices capable of providing not only immediate protection but also breaking the cycle of disease transmission.
As cyclones persist and the toll of diseases like dengue continues to escalate, the imperative for forward-thinking strategies becomes more urgent than ever. It is high time to advocate for solutions that transcend momentary reprieve, striving instead to create a lasting impact on the prevention and control of disease outbreaks and the tragic loss of lives associated with them.
Public health initiatives, community engagement and strategic planning for post-flood scenarios are essential to safeguarding communities from the dual impact of floods and mosquito-borne diseases. The time to act is now, for the health and well-being of communities depend on the collective response of people to this silent yet potent threat.
Susanta Kumar Ghosh, formerly with ICMR-National Institute of Malaria Research, Bangalore, and currently Scientific Advisor at Eco BioTraps.
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.
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