Flooding, building debris, and damaged drainage systems are creating new breeding sites for mosquitoes and flies. Implementing targeted vector surveillance, enhancing emergency drainage systems, and maintaining effective waste management can help.
Frequent flooding and landslides in Sumatra are commonly seen as the results of heavy rainfall. However, viewing them solely as natural events risks obscuring more fundamental issues.
Behind these disasters lie landscape changes caused by deforestation and land conversion, which not only exacerbate the impact of flooding but also increase the risk of zoonotic and vector-borne diseases.
Zoonoses are diseases transmitted from animals to humans, either directly or through intermediaries such as mosquitoes, flies, and rodents. The WHO notes that more than 60 percent of new infectious diseases in humans originate in animals, and most of their emergence is linked to environmental change and ecosystem disruption.
Disasters and public health emergencies
Floods and landslides create environmental conditions that are highly conducive to the spread of disease. Post floods, stagnant water in puddles provides an ideal breeding site for Aedes and Anopheles mosquitoes, spreading dengue and malaria. Data from the Indonesian Ministry of Health shows that an increase in dengue fever cases almost always follows major flooding, especially in areas with poor drainage.
Damage to sanitation infrastructure and clean water sources also increases the risk of waterborne diseases, such as diarrhoea and leptospirosis. Leptospirosis, a disease spread by water tainted with rat urine, tends to become more common following floods when people come into contact with this contaminated water. The Ministry of Health regularly reminds residents to be aware of leptospirosis in post-flood areas.
Refugee conditions exacerbate the situation. Overcrowding, limited sanitation, and disrupted access to health services also increase the risk of transmission of infectious diseases such as tuberculosis, measles, and pertussis.
Indonesia currently ranks second in the world for the number of tuberculosis cases, while basic immunization coverage in some areas of Sumatra, has not reached the national target.
Thus, environmental disasters can cause significant public health concerns.
Changes in landscape and vector behaviour
Landscape changes due to deforestation and disasters alter the dynamics of insect ecosystems. Flooding, building debris, and damaged drainage systems create new breeding sites for mosquitoes and flies. Land use changes in tropical regions significantly increase interactions between humans and disease vectors. Deforestation for agriculture, plantations, or settlements reduces wildlife habitats and forces vectors such as Anopheles mosquitoes closer to human populations. This process has been linked to increased malaria transmission. Deforestation for agriculture, plantations, or settlements reduces wildlife habitats and forces vectors such as Anopheles mosquitoes closer to human populations. This process has been linked to increased malaria transmission.
Loss of vegetation and soil erosion also force rodents out of their natural habitats and closer to human settlements. Loss of vegetation and soil erosion significantly impact rodent populations by destroying their natural shelters and food sources, forcing them to migrate or face higher mortality rates. When ground vegetation is lost, rodents become more exposed to predators. Rats, which serve as reservoirs for various zoonotic pathogens, are increasingly coming into contact with humans, especially in post-disaster areas. In this context, direct contact with contaminated food and water facilitates the transmission of diseases between animals and humans.
Post-disaster zoonoses
Natural disasters force interactions that were previously relatively rare. Wild animals that have lost their habitats move into gardens, fields, and settlements. Livestock that are usually kept apart from humans are now found closer to people, particularly at evacuation sites. Insects, which do not recognise boundaries between wildlife, livestock, and humans, move easily between the three.
These conditions increase the risk of zoonotic diseases such as dengue fever, malaria, and leptospirosis. These diseases are not only the result of the presence of vectors, but also of changes in human and animal behaviour in emergency situations. The One Health approach developed by the World Health Organization and Food and Agriculture Organisation emphasizes that human, animal, and environmental health are inseparable, and the case in Sumatra clearly reflects this.
However, various studies show that an increased risk of disease after a disaster is not inevitable. Implementing targeted vector surveillance, enhancing emergency drainage systems, and maintaining effective waste management are measures that can mitigate transmission risk within a comparatively brief period. The WHO recommends that disaster response should not only focus on logistical assistance, but also on evidence-based vector control.
However, in Indonesia, the response to post-disaster diseases tends to be reactive. The involvement of entomologists and environmental epidemiologists is not yet an integral part of disaster management. Yet, mapping vector species and their development patterns is crucial for determining effective and sustainable interventions.
The case in Sumatra shows that deforestation and environmental damage have direct implications for human health. Zoonotic diseases are a consequence of how humans manage nature.
Unless land management practices are strengthened and sustainable development practices are prioritised, the zoonotic disease outbreaks will continue to rise.
Sang Gede Purnama is a lecturer in the Department of Environmental Health, Faculty of Medicine, Udayana University. His research is on public health, focusing on topics such as dengue fever control, rabies, environmental risk identification, and disaster management.
Originally published under Creative Commons by 360info.
The post How floods and landslides are triggering deadly diseases in Indonesia appeared first on 360.
Source link
