Dead Bodies Do Not Spread Disease
January 15, 2010 in Medicine
You hear it after every natural disaster that causes large loss of life and the massive earthquake in Haiti this week has been no exception: Dead bodies spread disease. Well, no, not exactly. The short answer is that corpses are not an infection risk for diseases they didn’t already have.
Part of the myth likely comes from mass deaths during epidemics such as the bubonic plague (caused by the bacteria Yersinia pestis) or Tuburculosis (TB). Infected bodies can remain a potential source of infection for a short time after death but as is the case with infected live patients, transmission requires direct contact with infectious tissue or body fluids. In general, this would only apply to those tasked with removal, storage, and burial of the bodies and universal precautions should be taken when ever handing corpses, tissue, or body fluids.
TB is a particular problem as it can be transmitted via areosolized respiratory droplets either from opening the chest cavity (during autopsy or from initial severe trauma) or even from compression of the chest while moving the body. Precautions should be taken against airborne diseases such as TB if suspicion is high but even in the third world the prevalence of TB is only about 1% with far fewer having active pulmonary diseases at any given time. The likelihood that a cluster of bodies would have TB is extremely low unless something highly unusual happened such as a sanitarium collapsing or burning to the ground.
Unless there is direct or extensive contact without proper precautions with a recently deceased and infected body, the odds of direct transmission are extremely low. In the famous case of early biological warfare that occurred in 1346 when the Tartars besieged the city of Kaffa and catapulted the bodies of plague victims across the walls, the transmission of plague was likely not the result of contact with these bodies but rather from contact with fleas or flea-infested rats on the bodies or through the usual spread of the plague through the population during this time. And the chances that any one corpse from a natural disaster has an active communicable disease is no greater than that of the general population.
The other part of the myth likely comes from the decomposition of bodies over time. If not buried, cremated, or otherwise properly disposed of, bodies undergo putrefaction caused by common bacteria that usually reside in the bowel, on the skin, or in the environment. These bacteria assist and participate in the break down the tissues of the cadaver (putrefaction is prevented by embalming) and cause horrific changes. After several days the skin begins to turn a greenish color in large areas from the breakdown of iron containing blood cells. The break down of tissues and internal organs by bacterial metabolism creates large amounts of gas which is very foul smelling and causes the corpse to bloat and eventually rupture after which the tissue and internal organs liquefy. But as horrible as this process is, it is not a source either of the incubation or spread of disease and for all practical purposes, it is not harmful to others (two breakdown chemicals putrescine (1,4-diaminobutane) and cadaverine (1,5-pentanediamine) are responsible for the sickeningly sweet smell of decomposition and are toxic but only if swallowed in large doses and I’m not going there).
The main risk of disease transmission following a natural disaster comes from contamination of food and water sources but even here corpses have minimal if any influences. The loss of electricity hampers the proper refrigeration and preparation of food thus causing disease and food poisoning from spoilage. Broken plumbing and lack of power to generate water pressure and allow water purification facilities to function causes contamination of water sources from sewage and other ground contaminants. Even in disasters where bodies are left floating in rivers or stagnant water sources for days are not likely to be significant sources of disease. Most waterborne disease transmission following disasters is from people having to resort to drinking from untreated water sources and not being able to use properly functioning toilet facilities which further leads to cross contamination of water (and food) sources. Even mass burial of victims of natural disasters has not been shown to be a risk of bacterial contamination of ground water.
The seeming overemphasis on the disposal of corpses following a natural disaster (or massive act of violence) comes from our natural sensibilities and the need to avoid reminders of death and decay but is not justified from a public health hazard perspective. The biggest risk to the survivors of any disaster ironically comes from other survivors in the form of anything from violence and competition over limited food, water, and shelter to contamination of limited clean water and food sources.
Red Cross Aid for Haiti.