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Ebola virus goes rogue, but pandemic unlikely

Diseases jumping species to maim and kill have obvious sci-fi parallels, but few of us realise that many of the world’s most deadly infections come from animals.

columns Updated: Aug 02, 2014 23:42 IST
Sanchita Sharma
Sanchita Sharma
Hindustan Times
Ebola virus,world’s most deadly infections,zoonoses

Diseases jumping species to maim and kill have obvious sci-fi parallels, but few of us realise that many of the world’s most deadly infections come from animals. About 75% of new infections have animal origin (zoonoses), as are 60% of all viruses, bacteria, fungi and parasites that cause diseases in people.

Anthrax, dengue, E. coli, novel influenza viruses such as H1N1 (swine flu) and H5N1 (bird flu), Lyme disease, malaria, plague, salmonellosis, kala-azar, and West Nile virus are zoonoses that have made headlines for the wrong reasons. And they won’t be the last.

The newest virus gone rogue is the Ebola virus, which has infected 1,322 and killed 728 persons in Guinea, Sierra Leone, Liberia since February, and one man in Nigeria this week.

Ebola is a highly-contagious haemorrhagic virus that breaks down the cell wall of blood vessels and triggers extensive internal and external bleeding. Historically, the virus kills nine out of ten people it infects but in the current outbreak, the death rate is a lower 60%.

Unlike in the past where Ebola outbreaks remained localised -- the biggest recorded outbreak till now infected 1,200 and killed 672 in 1976, the year the virus was identified -- and was contained within weeks, the current outbreak shows no signs of petering out.

From its epicentre in forest and peri-forest areas around the shared borders of Guinea, Sierra Leone and Liberia in West Africa, the infection has moved to villages and cities, and now to a new country, Nigeria, where an international traveller died after getting infected in Liberia.

There are no drugs or vaccines to treat Ebola and treatment involves relieving the symptoms in strict isolation. Thus, stopping infection is the only solution.

World Health Organisation (WHO) head Margaret Chan admitted today that the Ebola outbreak is spreading faster than efforts to control it. But she added that the highly-contagious virus can be stopped because unlike air-borne influenza viruses -- H1N1 (swine flu) and H5N1(bird flu) -- the Ebola virus spreads through direct contact with blood and bodily fluids of infected persons and animals, which makes it less contagious than the flu.

Problems are plenty. There are not enough doctors and hospitals in the effected countries, and even when there are, people prefer local remedies and traditional healers. Then, there’s suspicion of modern medicine! which requires to abandon the infected in an isolated ward. Loved ones refuse to leave the bedside of the sick, and insist on the traditional rite of washing the body before burial even when told it remains contagious after death. Since hospitals don’t return bodies of people who die, people shun hospitals and hide the sick at home, or smuggle out the body of their loved one from the hospital for the last rites.

Though the exact cause of this particular outbreak is still not known, the consensus is that fruit bats – usually eaten dried or in a spicy soup – are to blame. Fruit bats are the natural reservoir species for the virus, which they carry without developing disease. Though the virus is killed when meat is cooked or heavily smoked, handling, butchering or eating food or fruit contaminated by saliva, urine, or faeces from an infected animal runs risk of infection.

Chances of travellers getting infected on a visit to West Africa remain extremely low, even if the visit includes travel to infected areas, says the WHO. Transmission requires direct contact with blood, secretions, organs or other body fluids of infected living or dead persons or animal, all situations to which an average traveller is unlikely to be exposed.

The Ebola virus has an incubation period of 21 days, and there is no infection risk during this period, with risk remaining low even at the start of symptoms. So, unless there is much bleeding or retching involved, travelling with a sick person in a flight carries very limited risk, but WHO recommends contact-tracing for three weeks to ensure fellow passengers don’t develop disease.

The WHO does not recommend travel restrictions or closure of borders, but to be super safe, get tested to rule out Ebola if you develop symptoms within three weeks of travel to the affected countries, exposure to an infected person, or eating undercooked, exotic meat to of West Africa.

First Published: Aug 02, 2014 23:40 IST