Ebola outbreak is cause for concern but there’s hope yet

Another reason for concern is that new cases have appeared unconnected to previous ones. Because Ebola is only spread by close contact, a key intervention is to identify the chains of transmission. Cases that present to hospitals usually represent a series of unidentified infections that need to be followed up.

Finally, there are reports of mistrust of authorities and misinformation that may be hampering an effective response. Although it’s difficult to tell how widespread these problems are, there have been reports of health-care workers being prevented from entering villages by armed men and attacks on treatment centers.

Infected patients are also reportedly being removed by force from treatment centers. Some families are said to be hiding sick relatives and seeking help from traditional healers. While this is completely understandable on one level for those involved, it also represents an ongoing risk of the virus spreading.

Some reasons for hope
But there are also some positive signs. Because the incubation period (the delay between contact and becoming unwell) is up to twenty-one days, current infections represent the state of control measures over that period. So the results of more recent control efforts are yet to be reflected in case numbers.

The good news is that it does appear the outbreak is coming under control in some areas, particularly in Guinea where the first cases were reported.

Health ministers of the countries involved are coordinating efforts so there’s clearly recognition of the seriousness of the situation. And the international community is pitching in with support from the World Health Organization and many non-government organizations that have experience in dealing with previous outbreaks, such as the Red Cross and Médecins Sans Frontières (MSF).

While there’s no specific treatment for Ebola infection, supportive treatment such as intravenous fluids and treatment of symptoms do help. The mortality rates reported early during outbreaks are almost always an underestimate, as reported deaths lag behind reported cases.

In previous Ebola outbreaks, between 50 percent and 60 percent of infected people survived, and these survivors may be protected against further infection. MSF has reported that the mortality of patients in their Guinea treatment centers is as low as 25 percent, compared to 56 percent for the outbreak as a whole.

Ebola is not as easily transmitted as some other infectious diseases, such as SARS, because it is not spread primarily by the respiratory route. In the first 1976 Ebola outbreak, only 20 percent of household contacts, where measures to prevent infection are presumably weakest, were estimated to be infected.

Identification of every single case may not be necessary. Studies suggest the average number of secondary cases that result from a patient with Ebola (known as the “reproduction ratio”) is less than three. If this ratio can be reduced to less than one (by identifying and isolating more than two thirds of the cases), then the epidemic will peter out.

Most of all, kudos should be given to the heroic efforts of those on the ground, mostly local health workers supported by a smaller number of international staff.

Several of them have reportedly been infected. People like them, who carry on this work in the face of uncomfortable protective equipment, the danger to their own lives and, in some places, the hostility of the population at risk, all deserve our respect and support.

Allen Cheng is Associate Professor in Infectious Diseases Epidemiology at Monash University. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).