By Oyinwa Alex-Okoh
Ebola virus disease (EVD) is a viral illness caused by the Ebola virus, a single stranded RNA virus which belongs to the Filoviride group of viruses. The first recorded outbreak of EVD occurred concurrently in Zaire (now the Democratic Republic of Congo) and Sudan (1976); it affected 602 people, out of which 431 (72%) died. In the almost 40-year period since then, few (~15) other outbreaks have been recorded.
Ebola is a disease that instills a lot of fear in people, and rightfully so. There is no cure, no vaccine, and the disease has a very high mortality rate (50–90%). The sporadic nature of outbreaks is probably one of the reasons that very little knowledge and treatment exist. Ebola is not airborne in humans; rather it is spread through direct contact with infected body fluids such as sweat, blood, vomit, saliva, and feces, and only a symptomatic carrier is contagious.
Throughout the summer, the Ebola outbreak in West Africa captured headlines and stoked fears about public health. The World Health Organization (WHO) has declared the current outbreak a “Public Health Emergency of International Concern.” Patient zero in this case is believed to have been a two-year-old child in Guinea who may have gotten Ebola from eating “bush meat.” The child infected his caregivers—his mother and grandmother—who then had contact with other people who subsequently got infected. The disease was then spread to the two neighboring countries: Liberia and Sierra Leone. These countries, some of the poorest in the world, were unprepared to handle such a disease that had never occurred in this part of Africa before. The lack of public health education, infrastructure, and healthcare services further fueled the spread of the disease, which has so far infected over 3,000 people and killed over 1,500. EVD has been reported in five West African countries: Guinea, Liberia, Sierra Leone, Nigeria and Senegal. A separate and unrelated outbreak has been reported in The Democratic Republic of Congo.
The early signs and symptoms of EVD, such as fever and muscle pains, are very similar to other common local diseases such as malaria and typhoid fever, and as such healthcare workers and caregivers, the most at-risk group, initially did not think to take necessary precautions. Now, however, due to the fear of the disease, many healthcare facilities are refusing to treat people with these symptoms. As a result, people are not only dying from Ebola, but from other treatable diseases. In the absence of a treatment or cure, public health tactics such as contact tracing and quarantining of suspected cases are the measures being used to contain the outbreak. Some people are able to survive EVD, especially those who seek medical care early; the current standard of care is supportive care, which includes rehydration therapies, blood transfusions and treatment of other symptoms.
In July, two American aid workers volunteering in Liberia were infected with the deadly disease. They received an experimental drug, ZMapp, a serum of monoclonal antibodies specific to the Ebola virus. This was a highly controversial move for two reasons: (1) Safety reasons—the drug had not yet been FDA approved, and (2) Ethical reasons—only Westerners got the drug. Normally, in order to receive FDA approval, drugs have to go through stringent preclinical and clinical trials to show that they are efficacious and safe for human use. The issue is that conducting clinical trials takes time—about eight years—and these therapeutics are needed immediately, as more than 40% of the 3,000 cases occurred in the past three weeks.
One of the problems with accelerating large-scale production of ZMapp is that the drug is grown on tobacco plants, and it takes several weeks to be manufactured, and current supplies have been exhausted. The Liberian government was able to secure the last available doses of the drug from Mapp Biopharmaceutical Inc., which they administered to three doctors who contracted the disease whilst treating infected persons. Two of these doctors survived. Both American aid workers have been cured and a British volunteer nurse who was treated with ZMapp has also been cured of the disease. To date, one Liberian doctor and a Spanish priest are the two known cases where the patient received ZMapp and did not survive. In summary, five of the eight EVD patients treated with ZMapp recovered, showing a 74% success rate of the drug. Clinical trials are not so simple. In addition to determining if the drug effectively treats the target disease, trials investigate potential side effects and help determine dosage, and this is usually done on a large number of people; the larger the sample size, the better.
Other drugs are being developed to aid in the war against Ebola. Canada donated an experimental vaccine that had shown promising results in preclinical studies. The NIH began trials on a vaccine last week and there are three other vaccines funded by the Department of Defense at various stages of development. There is an FDA provision for this; however, the fast track designation facilitates the process and allows urgently needed medicines to be available sooner.
*To learn more about the processes involved in regulatory affairs and in proving that a drug is safe for human consumption, you may refer to the AAPS Regulatory Affairs 101 eCourse. This comprehensive, online course contains information on the procedure from which drugs are developed in the lab to when they are deemed safe to be placed on the market.