Natural disasters are not the monopoly of any one country. Sometimes it is not the event itself but the aftermath that harms
more lives. Frequent fallouts of natural disasters, especially when they occur in the heat of the summer, are water-borne
diseases and vector-borne diseases.
Two recent and somewhat similar natural disasters affected two very distant countries: the July floods in Mumbai (formerly
Bombay), India, and the August flooding in New Orleans, U.S.A.
Mumbai is a city of 18 million people, located on the west coast of India, surrounded on three sides by the Arabian Sea. One
day this past July, the area received nearly one meter of rain. In the resulting floods, some 900 humans and thousands of
animals died, and millions were displaced from their homes.
New Orleans is a city of 600,000 people, located on the southern coast of the United States, by the Gulf of Mexico, and criss-crossed
by a myriad of waterways. When Hurricane Katrina moved inland off the Gulf of Mexico and into Lousiana in August, the rains
and the subsequent destruction of the seawall resulted in the flooding of most of New Orleans. The number of dead could end
up in the thousands and the entire city needs to be evacuated.
Both floods occurred in warm, humid climates, and saw sewage and corpses floating in the streets. Such breakdowns in sanitation
systems and contamination of drinking water evoke fears of water-borne diseases, which are contracted by either drinking or
coming into direct contact with contaminated water. The incubation period, the time between when the person is exposed to
the contaminated water and symptoms of the illness arise, can range between a few days to several weeks. The general symptoms
include fever, stomach cramps and diarrhea. In developing countries, many of the affected are children, a significant number
of whom die from dehydration, malnutrition, other complications, and lack of antibiotics. The World Health Organization (WHO)
estimates that each year nearly two million children worldwide die from such diarrheal diseases, most under five years of
age.
Water-borne disease
Different types of water-borne diseases are prevalent in different parts of the world. For example, this time in Mumbai, one
water-borne disease expected was cholera. New Orleans, however, is expecting to see mostly cases of hepatitis A.
Cholera is an acute intestinal infection, contracted by drinking water or eating food contaminated with the bacterium Vibrio cholerae. Incubation period is usually two to three days. Symptoms include profuse watery diarrhea and vomiting. Rapid loss of body
fluids can lead to dehydration and shock, and without treatment, death can occur within hours. Common treatment is replacement
of lost fluids and electrolytes using oral rehydration solution. Severe cases may require intravenous fluids and antibiotics.
Cholera is endemic to India: the WHO estimates roughly 25,000 cases a year, with a fatality rate of 1%. From time to time,
the U.S. has also had cases of cholera, usually along the Gulf of Mexico.
Hepatitis A is inflammation of the liver caused by the virus hepatitis A. The incubation period is 15-45 days, before the
first signs of illness appear. Symptoms are largely flu-like: fatigue, loss of appetite, nausea, low-grade fever, pale stools,
dark urine. Skin and eyes may also become yellow because the liver is unable to process the bilirubin in the blood. Treatment
involves rest, and avoiding alcohol and fatty/oily foods. Recovery generally takes three to six months. Several effective
vaccines are also available, and in August 2005 the U.S. Food and Drug Administration reduced the permissible age for vaccination
from two years of age to one. The U.S. sees about 9000 cases of hepatitis A yearly.
For more information, please see the AboutKidsHealth A-Z Health Library article on Hepatitis A.
In Mumbai the July floods have already resulted in some 150 deaths due to water-borne diseases. Most of these deaths were
because of one specific but lesser known water-borne disease called leptospirosis, caused by exposure to water contaminated
with animal urine: many people had to wade through neck-deep contaminated water to get to safety. The symptoms are high fever,
severe headaches, muscle pain, chills and vomiting. The U.S. government’s Centers for Disease Control and Prevention (CDC)
have also recently added leptospirosis as another possible illness to expect in the aftermath of Hurricane Katrina.
Vector-borne disease
Now, several weeks after the floods in Mumbai, the incidence of water-borne disease is on the wane but there are rising cases
of vector-borne diseases. Vector-borne diseases are those that are transmitted to humans by an insect. They are often caused
by the mosquitos that breed in the stagnant waters, such as those left behind after a flood. Mumbai is seeing rising cases
of malaria. In New Orleans, with the receding of the floodwaters, U.S. health officials fear an increase in cases of the West
Nile virus.
Malaria is caused by parasites transmitted by the Anopheles mosquito. The parasites migrate to the liver of the patient and
then enter the bloodstream, infecting the red blood cells. The incubation period is one to three weeks. Symptoms include fever,
chills, headaches, muscle pain, and anemia. Several types of anti-malarial drugs are available. The CDC estimates there are
about 300 million cases of malaria worldwide each year, of which more than one million die, mostly children. India has about
two million cases a year, of whom 650 die.
The West Nile virus is another disease transmitted by mosquitoes. The incubation period is two to 15 days. Most people infected
with the virus will not experience any symptoms, some will experience mild flu-like symptoms, and less than 1% will develop
a severe form of the disease which affects the central nervous system. No specific treatment exists, or is needed, unless
the central nervous system is affected. The U.S. sees about 2500 cases a year and about 100 deaths. India has its own version
of the West Nile virus, a related disease called Japanese encephalitis. Parts of northern India are experiencing an outbreak
of it this year, in which over 2000 children are affected and already over 500 have died.
Combating water-borne and vector-borne diseases
Many water-borne illnesses are bacterial in nature and can be fought with antibiotics; however rehydration is also a major
aspect of the treatment. In its “Flooding and Communicable Diseases Fact Sheet,” the WHO suggests several ways to combat water-borne
diseases:
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Use clean drinking water.
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Water can also be purified by boiling or treating with chlorine.
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Use oral rehydration salts to treat dehydration.
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Use appropriate antibiotics to combat bacterial infection.
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Use analgesics to reduce fever.
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Wash hands well with soap and clean water.
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Wash any unpackaged food in clean water. Avoid any food that may have come into contact with contaminated flood water.
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Wash all clothing that has been in contact with contaminated flood water.
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Disinfect all children’s toys that have been in contact with contaminated flood water.
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Vaccinate against hepatitis A.
The CDC suggests the following ways to protect against vector-borne diseases, such as West Nile virus:
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Use insect repellent with DEET, picardin, or oil of lemon eucalyptus.
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Be especially wary at dawn and dusk because more mosquitoes are active then. Wear long sleeves, long pants, and socks when
outdoors.
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Put screens on open windows and use nets over beds.
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Drain standing water.
In both India and the U.S., such floods are not a one-off event. In India, the Monsoon rains sweep across the country each
year from June to September, often flooding various parts of the country. The resulting breakdown of the sanitation system
and contaminated water cause water-borne diseases. Later, the stagnant water is a breeding ground for vector-borne diseases.
In a more developed country like the U.S., such diseases generally occur to a lesser degree and in a more controlled manner,
except when struck by a natural disaster like Hurricane Katrina. However, this year the National Hurricane Center is expecting
an extremely active season in the Atlantic over the next few months, bringing 11 storms, seven becoming hurricanes, and three
of those becoming major hurricanes. Better preparation against water-borne and vector-borne diseases is necessary on both
sides of the world to ride out the upcoming storms and the resulting floods, and to minimize risk and damage to human health
and life.
