The current outbreak of Ebola virus disease in West Africa, which began last December in Guinea and has since spread to Liberia and Sierra Leone, has already caused 779 cases, including 481 deaths. This makes it much larger than past outbreaks, and it has generated extensive media coverage worldwide.
It is not difficult to explain the macabre interest in Ebola. The virus can kill up to 90% of the people it infects. It causes a horrible death, with initial symptoms of fever and muscle pain followed by vomiting, diarrhoea, kidney and liver damage, and sometimes profuse internal and external bleeding. Despite these tragic effects, a sense of perspective is required. Since the virus was first discovered in Zaire (now the Democratic Republic of the Congo), there have been only a few dozen sporadic outbreaks — most of them small and largely confined to central Africa.
Ebola is a rare disease that, in some 40 years, has resulted in barely 2,000 deaths. Although even one premature death is too many, the toll of Ebola pales beside the millions killed every year in Africa by other infectious diseases. These include HIV/AIDS, malaria and influenza, as well as measles, diarrhoea and pneumococcal pneumonia, which rarely get such attention from the media. Ebola also poses a very low risk to travellers and those outside the affected region, as long as they take basic precautions against infection.
Ebola seems to hold little or no pandemic threat. Unlike an outbreak of a new pandemic flu strain, which is impossible to contain, Ebola spreads poorly between people. Its transmission requires direct contact with the bodily fluids of those who are infected, such as saliva, faeces or blood. This also means that, even in the absence of a licensed Ebola vaccine, stopping an outbreak in its tracks should, in principle, be straightforward. The disease can be controlled by public-health measures alone, such as surveillance and diagnosis of those infected and their contacts, prompt quarantine of cases and other basic infection control.
“Stopping an Ebola outbreak should, in principle, be straightforward.”
It is not known how the current outbreak began. Fruit bats that serve as a probable reservoir of Ebola are present in the remote forest in southeast Guinea where this outbreak was initially reported, and the disease is thought to have jumped to humans through contact with contaminated bushmeat or infected primates. However, the continuing outbreak, which is now affecting dense urban populations, is mainly being driven by human-to-human spread: traditional burial practices that include contact with corpses, sick people not getting or seeking care, and a lack of basic infection-control measures.
The difficulties in implementing the necessary public-health measures in Guinea, Liberia and Sierra Leone, which are among the poorest countries on the planet, are formidable. Because people in these regions are often poor and many are illiterate, it is not easy to communicate the risk factors for Ebola and the infection-control measures needed — particularly when the disease, and the biohazard suits of health-care workers, can strike terror into the hearts of affected communities. Some workers have reportedly been attacked by locals who believed that they had brought in the disease.
As with social resistance to vaccines in even the richest countries, sometimes diseases continue to cause illness and death — not because of a lack of tools to stop them, but because of the difficulties of conveying public-health measures and overcoming fixed, but misplaced, beliefs.
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