August 31, 2014

West African Ebola – what is the true Case Fatality Rate?
Paul Conton, MSEE

Up until this year the largest Ebola outbreak the world had witnessed was in Uganda, centered around the town of Gulu. By the time the outbreak was eventually contained, some 425 patients had been infected with the virus, of whom 224 died (Case Fatality Ratio = 53%). Are there lessons we can draw from the Ugandan experience in this West African outbreak? How were the Ugandans able to defeat Ebola? What mistakes did they make and what worked well?

Uganda was fortunate (or, depending on your point of view, sufficiently vigilant) that the outbreak was for the most part contained in the district of Gulu, which experienced 93% of the cases. It did spread to two other areas but was quickly contained there. In Gulu it was more difficult, and at one point appeared to be out of control. One of the best accounts of the Uganda outbreak (xxx) tells the story of Dr Mathew Lukwiya, who became famous for his handling of the emergency in Gulu; he is credited with the early diagnosis of Ebola, which was then an unknown disease in Uganda, and with quick institution of an isolation ward, thus preventing the spread of the disease to other areas. This notwithstanding, many of the features that we see here in West Africa, were very much present in Gulu. The denial, the association with witchcraft, the fear, the infection of hospital workers and near breakdown of the health care system.

How was the disease contained? It's unclear from the accounts whether any one factor can be credited with the ending of the outbreak in Gulu. According to WHO's Epidemiology of Gulu Ebola

Yes, Dr Mathew worked heroically in his hospital, but at the end of it all Dr yyy, who worked in another hospital in Gulu had this to say, "         ". Contact tracing and quarantining certainly played a role. There is some talk of the disease burning itself out, although the precise mechanism of this is unclear. Certainly in West Africa we see no evidence of this at this point.

Health workers were frequently struck down by Ebola in Gulu, to the point that the hospitals were almost overwhelmed. There were at least two approaches to this problem. Dr Mathew used his hospital staff exclusively to treat patients and towards the end they nearly rebelled against him.  In other hospitals, doctors encouraged a spouse or family member to be the primary caregiver for each patient. Wearing protective clothing, caregivers cooked for and cleaned up after their loved ones. The system reduced risks for nurses and nursing assistants, keeping them away from infectious body fluids.
"There is no right answer to the question of how to nurse Ebola patients in Africa," said Dr. Daniel Bausch, a C.D.C. medical epidemiologist who worked in northern Uganda last fall and managed the Ebola ward at a small government hospital in Gulu town. In many African hospitals, it is less a matter of best medical opinion than of what is possible. Dr. Bausch used family caregivers on the Ebola ward at Gulu Hospital because he said he had no reasonable alternative.

Whatever its medical or epidemiological value, Dr. Matthew's system became a management nightmare. He tried to reassure nurses and nursing assistants that the risk   was tolerable. Yet as the weeks went by, Ebola insidiously eroded his authority.

Health-care workers wore their protective gear, they managed their risks and still they got sick. Twelve of them died.

Dr yyy used patient relatives to do much of the caring and thus spared his staff. Apparently there is some divergence in the medical community on this. There has also been talk of using Ebola survivors for some of the caring, as Ebola survivors at least theoretically have immunity and will never again get the disease. This would take some of the pressure off trained health workers. Much of the duties with Ebola care involve cleaning and assistance that do not require trained health personnel. If these routine duties could be undertaken by other, non-health personnel, it would free the health personnel for strictly medical duties.

It may be that by the process of natural selection the virus gets more and more deadly with each new outbreak. The organisms that thrive and multiply are the ones that are best able to mutate and adapt to their new environment. And because the replication rate is so rapid, mutation can occur in a relatively short space of time.

octors who treat Ebola are not convinced that they have a whole lot to offer any patient. They estimate that using IV drips to replace lost fluids might make a difference for about 10 percent of those who get sick. For others, they guess, the seriousness of the illness depends on the genetic makeup of a patient, the amount of tainted blood or other body fluid that has come in contact with a patient and the route of infection. The prick of a bloody syringe, for example, is almost certainly worse than a cough in the face.
"Ebola is a tough disease," Dr. Bausch said. "I am not so sure that once someone is infected that the treatment we offer prevents more people from dying than would have died anyhow.