Flood diseases

Flood diseases


Associate Professor Dr. Supakorn Rojananin, M.D.

Deputy Dean of Public Relations and Special Affairs

Faculty of Medicine Siriraj Hospital, Mahidol University


            During the rainy season, many regions of the country were hit by rounds of typhoon or tropical depression storms resulting in not only the housing damage but also the casualty and death. Flooding is also a consequence that followed from heavy rain falling, overflow river and un-drained water path. Floodwater can rapidly be contaminated with sewage water, human waste, animal waste, animal dead bodies, regional soil pathogens as well as dirty solid particles, and chemicals. Flood water can also be the source of vector breeding sites and venomous animals. Therefore, if there is no well organized measure and public instructions for having a good sanitary condition, individual injuries or endemic and epidemic diseases may occur.


            The recent study of water after 4 days of flooding in a village of East Jakarta on January 2005 by Phanuwan et al., they found that E coli bacteria and enteric virus, hepatitis A virus, for examples, were significantly higher in flood water than river water. These bacteria and viruses were also observed even in the groundwater in the flooding area which indicated that the flooding event posed a risk of fecal and pathogenic contamination into drinking water system. No such pathogens were observed in the groundwater samples in non-flood area.


            Floodwater test in New Orleans after just being hit by Hurricane Katrina, released by Environmental Protection Agency, found that the levels of sewage-borne bacteria were extremely high to unsafe levels of pathogens that could transmit diseases, such as Hepatitis A and salmonella. However, most of the chemicals including pesticides, hydrocarbon, (except lead) were not exceeded concentrations that posed human health risks if the water was ingested.


            The most common endemic diseases in the flooding area are transmitted or spread through the contaminated water as called “water-borne disease”. Many pathogenic microbes (bacteria and virus) and some parasites are responsible for various diseases such as cholera, dysentery, hepatitis A, typhoid fever, amoebiasis and leptospirosis.


            All the diseases as mentioned except leptospirosis are gastro-intestinal diseases follow a transmission pattern that is called fecal-oral route. All the pathogens are released and stay in the flood water with feces and re-entry to human again through the oral route with contaminated food and water. 


             Cholera presented as an acute severe watery diarrhea caused by Vibrio Cholerae. Shigellae cause dysentery diarrhea presented with mucous or mucous-bloody stool which sometimes is similar to the amoebic dysentery. Typhoid fever caused by salmonella bacteria may or may not present with diarrhea at the onset of infection but its actual clinical manifestation is a type of fever called enteric fever. 


             Leptospirosis is a disease caused by Leptospira interrogens, the bacteria released to the flood water or mud from the infected rat or domestic or wild animal urine and enter the human body via wound or skin abrasion while walking bare-foot through it.


            Individual diseases, accident and danger from animal bites are also common. Wading or immerging for so long in dirty water may have fungal as well as bacterial infection of foot which sometimes produce blebs, swelling, cellulitis and severe fascio-myositis and sepsis especially in the compromised persons or patients with diabetes, cirrhosis, chronic venous or lymphatic ulcers or who have cut or foot ulcer . Bare-foot walking or children playing in the flood water may prone to the accidents from sharp broken glasses or household objects. Danger from venomous animals such as snakes, centipedes, scorpions are also common in the rural areas.


             Dr. Pornpan Koomanachai, Division of Infectious Diseases and Tropical Medicine, Department of Medicine, Faculty of Medicine Siriraj Hospital, recommends that if flooding lasts more than a few days period, flood water will carry disease and other contaminants. Therefore, ones should wash the hands with soap every times after contacts or after using the toilet or handling contaminated items as well as before preparing and eating. Adequate clean water supply (at least 20 liters per person per day) and regular hand washing is the key success for good sanitation and hygiene. Be sure that there is no cross contamination of the drinking water, if doubtful, boiling before use is necessary. All flooding areas where groundwater is used for drinking should be assumed that it is already contaminated. Foot cleaning, disinfection of clothes or contaminated belongings and avoiding the children to play in the floodwater is also recommended.


            Local health department should prepare for the flood, provide adequate clean water and emergency supplies, monitor the level of contamination of the floodwater periodically and call for public alert and instructions to prevent the outbreak, provide for vaccination and order to evacuate at time before the situation becomes worse.


            For those people in flooding area, if any ailments occur, go to see the doctor for early diagnosis and treatment before the symptoms deteriorating and complication develop.