Disaster aftermath: The risk of epidemic diseases

Natural disaster can kill hundreds of thousands of people a year. But the aftermath can keep on claiming lives. Outbreaks of infectious diseases following hurricanes, cyclones, tsunamis and earthquakes are not uncommon in the developing world.
Earthquake survivors walk amidst collapsed buildings and rubble in downtown Port-Au-Prince, Jan. 14, 2010. ((Julie Jacobson/Associated Press))

Long after the immediate threat passes, a natural disaster can continue to take a deadly toll.

Outbreaks of infectious diseases following hurricanes, cyclones, floods, tsunamis and earthquakes are not uncommon in the developing world. They are rare in developed countries.

Most post-disaster disease is spawned by poor sanitation, a lack of safe drinking water and contaminated food.

The Canadian Forces' Disaster Assistance Response Team has been dispatched to several natural disasters — in part — to help provide safe drinking water and reduce the risk of disease outbreak.

Here's a rundown of some of the diseases that can afflict survivors of disasters:


Cholera is an intestinal infection caused by the bacterium Vibrio cholerae. People contract it from drinking contaminated water or eating contaminated food. It may be the biggest disease threat to survivors of disasters because it progresses rapidly. It can kill an individual in less than a day.

The infection leads to severe diarrhea — leading to the loss of up to 10 litres of bodily fluids in a day. That causes rapid dehydration, shock and the risk of death.

However, most people who become infected don't get sick. The vast majority of people who do show symptoms will develop mild or moderate cases of the disease. Those cases are often indistinguishable from other types of acute diarrhea.

Typhoid fever

Typhoid fever is caused by the bacterium Salmonella Typhi. You get it by eating food or drinking fluids handled by an infected person. You can also get it if sewage contaminated with Salmonella Typhi
Doctors and nurses tend to stricken patients along the corridors of a government hospital near Manila, Philippines. More than 1,400 people displayed typhoid symptoms in March 2008 in Calamba, a city near the Philippine capital. ((Bullit Marquez/Associated Press))
bacteria gets into the water you use for drinking or washing.

The illness is uncommon in the developed world — most North American cases involve people who have travelled to developing countries.

Typhoid fever affects about 21.5 million people a year.

Symptoms of the disease include sustained high fever of 39 C to 40 C, a feeling of weakness, stomach pains, headache, or loss of appetite. Some people suffer from diarrhea. Others develop constipation. In some cases, patients develop a rash of flat, rose-coloured spots.

Among the most serious complications are intestinal bleeding or perforations.

The disease is treatable with antibiotics and there is a vaccine that can protect people. But for those trying to cope with a natural disaster in less-developed parts of the world, a lack of access to treatment increases the risk that the complications may prove fatal.


This is yet another disease that can be spread through contaminated drinking water, although it can also be caused by a parasite living in one's gut. The vast majority of cases are caused by bacteria.

Dysentery results in diarrhea in which there is blood and pus. In rare cases, it can kill individuals within 24 hours.

However, most cases clear up on their own, without treatment.

The main symptom is frequent, near-liquid diarrhea flecked with blood, mucus or pus. Other symptoms include:

  • Sudden onset of high fever and chills.
  • Abdominal pain.
  • Cramps, bloating and flatulence.
  • Urgent need to pass stool.
  • A feeling that you still have to go.
  • A loss of appetite.
  • Headache and fatigue.
  • Vomiting and dehydration.

If dehydration becomes severe, an infected person could be at risk of coma or death.

Dysentery is treated through rehydration and antibiotics.

Hepatitis A and E

These diseases spread under unsanitary conditions, through human feces. People catch the virus by taking in contaminated water or food.

No specific treatment or antibiotic drug exists for either hepatitis A or E. Those suffering are urged to rest, stay hydrated and try to eat nutritious foods.


This condition — another gut-wrenching infection — is also caused by coming into contact with contaminated water. It is more commonly spread in areas where people and pigs live in close proximity.

Many pigs carry the bacteria that cause balantidiasis and it can be passed from pigs to humans. It can also be spread when pig feces get into water humans use for washing or drinking.

There have been outbreaks of balantidiasis in areas struck by typhoons. Symptoms of the condition include chronic diarrhea, occasional dysentery, nausea, foul breath, colitis, abdominal pain, weight loss, deep intestinal ulcerations and possibly perforation of the intestine. Left untreated, it can kill. However, in most cases, people with the condition show no symptoms.


Contaminated drinking water can bring on yet another condition — leptospriosis. You're at risk when water is contaminated by the urine of animals that carry the bacteria that causes leptospriosis — cattle, pigs, horses, dogs, rodents and wild animals.

Symptoms include high fever, severe headache, chills, muscle aches and vomiting. Those infected can also develop jaundice, red eyes, abdominal pain, diarrhea, or a rash.

If left untreated, the patient could develop kidney damage, meningitis, liver failure and respiratory distress. In rare cases, leptospriosis can kill.

It can be treated through antibiotics.

There was an outbreak of the disease in 1996 in Puerto Rico in the aftermath of a hurricane.

Animal bites, arthropod bites, stings

You may not be the only one competing for safe spaces in the wake of a natural disaster. Creepy, crawly
Cattle find refuge on a narrow strip of dry land in the flooded Bolivian state of Beni in Feb. 2007. Months of severe flooding triggered a dengue fever outbreak across Bolivia's lowland tropics, killing 35 people. ((Juan Karita/Associated Press))
creatures could be on the move as well if their breeding sites or natural habitats are ravaged.

If you're in a tropical country, you may be at increased risk of bites from poisonous spiders and snakes. As well, mosquitoes may become more of a threat, if they've been forced to move on to other breeding grounds.

You could be at risk for:

  • Malaria — an infectious disease spread by mosquitoes, mainly in tropical climates. Symptoms, which begin showing up 10 to 15 days after infection, include headache and fever, chills, muscle and joint pain, nausea and vomiting and convulsions. If not treated promptly, you could die.
  • Dengue fever — another infectious disease spread by mosquitoes. Symptoms include sudden onset of fever, with severe headache, muscle and joint pains and rashes. Cases often clear up within six to seven days. However, in severe cases, death can result.

You're not in the clear yet

For those who survived the disaster but lost their homes and had to seek shelter in an emergency centre, there are additional risks. Diseases such as infectious hepatitis, gastroenteritis, measles and tuberculosis could catch up with victims of a catastrophe stuck in a crowded shelter with insufficient sanitary facilities. This can be compounded in countries where immunization rates are low.

The myth about corpses

In major disasters, there may be a large number of unburied corpses. In a natural disaster, the vast majority of those people were killed by the trauma of the storm — not disease. While the decomposing bodies will give off a terrible smell, they will not spread epidemic infectious diseases. The decaying body of a previously healthy person is not a disease risk.

A study published in the May 2004 edition of the Pan American Journal of Public Health found that the risk of epidemics from the bodies of people killed in natural disasters in negligible. The researchers found that epidemics resulting in mass fatalities after natural disasters have only occurred from a few diseases — such as cholera, typhoid, tuberculosis, anthrax and smallpox. While those diseases can be highly contagious, they cannot survive for long in dead bodies. The study found that survivors are far more likely to spread disease than corpses.

The researchers noted that unfounded concerns about the infectiousness of corpses sometimes leads to the rapid, unplanned disposal of the dead — often before victims are identified, making it harder for survivors to mourn their loss.