Flooding and Infectious Disease Risk Worldwide

Increased rainfall and flooding in many regions of the world have heightened the risk and concern over the transmission of water-borne diseases. Oftentimes during flooding, population displacement and contamination of water sources can lead to major outbreaks of diarrhea, dysentery and even cholera and typhoid fever. Risk of infection is also increased when victims, especially children, come in direct contact with polluted waters and develop wound infections, dermatitis, or conjunctivitis. In the long term, water disasters can leave pools of standing water that create optimal breeding grounds for mosquitoes and increase the risk of vector-borne illnesses such as dengue, malaria, and West Nile. Currently, the onslaught of rainfall and flooding have wreaked heavy damage and increased risk of disease outbreak in the regions of Brazil, Southeast Asia and Australia.


Heavy rainfall in Brazil during this summer season, especially last week, has been extremely problematic causing severe flooding and landslides in Rio de Janeiro’s mountainous region. In just one day the region experienced 95% of the expected rainfall for the entire month of January. Cities like Teresopolis, Petropolis, and Nova Friburgo have been hit very hard with over 400 deaths so far.  As of today, January 18, the death toll in the country is at 677 with about 14,000 homeless due to the heavy rains. This is considered the worst disaster in Brazil’s history (in terms of deaths) surpassing the flood in Sao Paulo state in 1967, which killed 436 people. Government officials worry that these heavy rains could bring disease epidemics to Brazil. The Agency of Civil Defense began distributing vaccines for tetanus and diphtheria in an attempt to prevent infections.

Sri Lanka and Philippines
Heaviest rains in nearly a century and flooding in Sri Lanka has so far left 40 dead, 4 missing, and over 325,000 people displaced. More than 27,000 houses were damaged and victims were forced to evacuate to over 200 camps located on higher grounds. Although in the past days water levels have begun to recede and people are returning to their homes, they are faced with the risk of water-borne diseases in these regions. Those living in the temporary relief camps also remain at risk. Sri Lanka’s government is reportedly mobilizing resources and medical supplies to these areas and making an effort to strengthen the disease surveillance system to prevent any potential outbreaks. According to health ministry officials, so far no cases of such disease have been reported.

Severe flooding and landslides in Philippines have so far spanned 25 provinces and have left at least 50 people dead and 1.5 million people affected. In addition to washing away houses and destroying crops, the flooding may result in large-scale disease outbreaks. According to one rescue unit, one region has reportedly had several hundred cases of dysentery, although this has not been officially confirmed.

In the aftermath of the worst flooding seen in Queensland in centuries, health authorities warn of the potential of infectious disease infections. Already, several cases of melioidosis, which has not been reported in Brisbane since the 1974 floods, have surfaced and large amounts of pooled water could potentially result in a surge in mosquito numbers, leading to increased risk of mosquito-borne illnesses such as Ross River virus and dengue fever. Fecal contamination of water from sewage and the possible spoilage of food from when the power was cut raises concern over food-borne illnesses such as E.coli and salmonella. Many Queensland clinics have already seen an influx of patients seeking tetanus vaccines as a precautionary measure. Although health officials say there has not yet been a rise in gastrointestinal cases, they expect the number of patients with infections to swell if food, water, and sanitation continues to be compromised.

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