Over the past decade, various outbreaks of the deadly Ebola virus disease have been recorded with three countries appearing to be at greatest risk – Democratic Republic of Congo, Uganda and Sudan. Among these, the most fatal happened in 2011, 2005 and 2003, with 100%, 83% and 83% case fatality rates (CFR) respectively. Public health physicians rely on case fatality rates as an indication of the severity or risk of death during an outbreak and measure CFR by quantifying the proportion of diagnosed people who die over a specified time period. Generally known to strike with a case fatality of 90%, the first two simultaneous outbreaks were recorded in 1976 including one near the DRC village of Ebola from where the name was derived.
In Africa, fruit bats are considered natural hosts and reservoirs of the Ebola virus although Ebola outbreaks have been observed in chimpanzees, gorillas, macaque monkeys and in some pigs in the Philippines and China. These latter animals, like human beings, have been considered as “accidental hosts” and not reservoirs of the Ebola virus.
In the wake of an outbreak of the disease in the West African sub region, concern was further stimulated when a suspected case of Ebola virus infection was reported in the Komfo Anokye Teaching Hospital. Thankfully, rapid laboratory investigations carried out have proved negative. With Ghana on the alert and its public health experts moving into top gear, it is worth addressing public panic by reflecting over the profile of Ebola outbreaks and its effective prevention and management. A fact sheet recently released by the World Health Organization (WHO) has proved helpful in this regard, revealing that the Ebola virus is transmitted to people from animals and subsequently spreads through the human population through person to person contacts.
“Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals. In Africa, infection has been documented through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest. Ebola then spreads in the community through human-to-human transmission, with infection resulting from direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and indirect contact with environments contaminated with such fluids. Burial ceremonies in which mourners have direct contact with the body of the deceased person can also play a role in the transmission of Ebola. Men who have recovered from the disease can still transmit the virus through their semen for up to 7 weeks after recovery from illness.”
Given its high case fatality rates, prevention is critical. Efforts to control Ebola virus infection among domestic animals may include routine cleaning and disinfection with sodium hypochlorite or other detergents in monkey and pig farms, and quarantining the premises and restricting animal movement during suspected outbreaks. Essentially, an active animal surveillance system is required as an early warning mechanism as infections among especially pigs and monkeys are known to precede outbreaks in humans.
The risk of infection among humans from animals may be reduced by avoiding contact with fruit bats or monkeys etc. avoiding consumption of their raw meat and ensuring that all animal products are thoroughly cooked before consumption. Animal handlers are advised to wear gloves and other protective clothing.
Generally, close physical contact with suspected cases of Ebola virus disease should be avoided at home and in communities. Additionally, if having to attend to a sick relation at home, gloves should be worn and regular hand washing with soap is very important both at home and after visiting patients in the hospital. Because patients may first present in healthcare settings with non-specific symptoms, health care workers remain at serious risk through contact with blood and other body fluids especially if standard infection prevention methods are not routinely practiced and strictly adhered to. According to the WHO, health workers working within one metre of patients with Ebola virus should “ wear face protection (a face shield or a medical mask and goggles), a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).” Taking of samples should also be done by trained staff.
Signs and symptoms include “sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.”
It is to be noted that a person infected by the virus may incubate it for 2-21 days before showing any of the above symptoms. Diseases that could be mistaken for Ebola virus disease include malaria, typhoid fever, shigellosis, cholera, leptospirosis, plague, rickettsiosis, relapsing fever, meningitis, hepatitis and other viral haemorrhagic fevers. It is diagnosed through conducting blood tests in a laboratory.
No vaccines and/or definitive treatment are currently available although many are undergoing various stages of testing. Subsequently, treatment is largely supportive including managing frequent dehydration with oral rehydration and sometimes intravenous fluids in more severe cases.