Ebola Virus Disease has a High Fatality Rate

Robin building nest. (Dr. Noorali Bharwani)
Robin building nest. (Dr. Noorali Bharwani)

Ebola virus disease (EVD), as it is known now, was formerly known as Ebola haemorrhagic fever. It is a severe, often fatal illness in humans. It is a disease of the wild animals and then it is transmitted to people. It spreads in the human population through human-to-human transmission.

The Ebola virus causes an acute, serious illness, which is often fatal if untreated, says WHO website. Ebola virus disease first appeared in 1976 in two simultaneous outbreaks, one in Nzara, Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.

Previously the disease was confined to small villages near tropical rainforests. The most recent outbreak in West Africa has involved major urban as well as rural areas. The case fatality rates have varied from 25 to 90 per cent in past outbreaks.

Controlling the disease has been difficult. According to the WHO website, community engagement is key to successfully controlling outbreaks. Good outbreak control relies on applying a package of interventions, namely case management, surveillance and contact tracing, a good laboratory service, safe burials and social mobilization.

Currently there is no licensed treatment for the disease. Treatment is base on providing rehydration with fluids and treat any other symptoms that the patient presents with. A range of blood, immunological and drug therapies are under development.

The current outbreak started in March 2014 in West Africa. WHO calls this the largest and most complex Ebola outbreak since the Ebola virus was first discovered in 1976. There have been more cases and deaths in this outbreak than all others combined. It has also spread between countries starting in Guinea then spreading across land borders to Sierra Leone and Liberia, by air (one traveller only) to Nigeria, and by land (one traveller) to Senegal. Latest report has confirmed a case in the US. By the time you read this the numbers may change.

How does a person get infected with Ebola virus?

It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest.

How does it spread among humans?

Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.

WHO says people remain infectious as long as their blood and body fluids, including semen and breast milk, contain the virus. Men who have recovered from the disease can still transmit the virus through their semen for up to seven weeks after recovery from illness.

First symptoms are the sudden onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal and external bleeding (e.g. oozing from the gums, blood in the stools). Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.

Confirming the diagnosis and providing treatment continues to be a challenge. There is lot more information available on the WHO website.

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