The Art of Measuring Mortality in Africa
Has the number of deaths from Ebola dropped below expectations in Liberia? The New York Times poses the question:
Around the country, treatment centers, laboratory workers who test for Ebola, and international and national health officials trying to track the epidemic have noticed an unexpected pattern: There are far fewer people being treated for Ebola than anticipated.
Some consider the latest developments an indication that the efforts to combat the virus, including the opening of new treatment units, are beginning to succeed.
There is also the likelihood that many people dying of Ebola in Liberia are hidden from the authorities, as has been true throughout the epidemic.
Many parts of the country are not well monitored, many contacts of Ebola patients are not traced, and officials have long acknowledged that the statistics on the numbers of Ebola cases across West Africa are rough estimates, at best.
Not only are Ebola cases rough estimates, the number and causes of deaths in general are rough estimates throughout Africa. I was thinking about this today when Marta Jankowska linked me to a new issue of Global Health Action, which just published a special issue on death data collected and analyzed by the INDEPTH Network. They have research centers in Africa and Asia that aim to figure out the otherwise unknowable. Systems of vital registration are few and far between in much of Africa and Asia, so what we know about mortality comes from surveys and from the INDEPTH sites, along with questions about deaths of family members that have been inserted into recent population censuses. Unfortunately, as you can from the map below, none of the three Ebola-impacted countries of Liberia, Sierra Leone, and Guinea, has an INDEPTH site, so we are even more ignorant than normal about what's going on in those places.
Prof Weeks ... I think you have hit upon a serious weakness - in global reporting (of data).
ReplyDeleteWhich countries are likely to experience outbreaks? Of course, it is the impoverished ones with poor infrastructures, poor public health facilities, high crime, and general social disruption. Naturally, these are also the countries which DON'T have the global monitoring stations that collect data. Why should volunteers go to work in such high-risk areas?? It's just not an attractive proposition at the personal level.
I see this dilemma as something that is getting worse in the future ... not better. It appears to me that the number of "Failed States" in Africa is more likely to increase, rather than to decrease. Hence all of the problems associated with failed regions, including breeding grounds for new diseases, are likely to magnify. And it is quite likely that the reporting will be poor in the future, as well.
In the case of Ebola, I think the first recorded outbreak was in the mid-1970's (1976, in Congo or Zaire?). And there were subsequent outbreaks at a local villages in Africa, but in seemingly random locations. In the case of the disease AIDS, it has now been traced back to an initial outbreak in the 1920's in Kinshasa. So the point ... is that these "new diseases" have been around for many decades, before they eventually "go on a world tour". However, due to poor reporting ... they are not identified for a long time.
It seems entirely possible that the next big threat ... perhaps a new strain of Ebola ... or even an entirely new virus ... is ALREADY in existence in Africa now. It simply has not been reported or identified (correctly) yet. And maybe in another decade or two ... that new virus will go global.
Pete, Redondo Beach
BTW, just heard some data that the mortality rates for Ebola patients are very age-dependent. Ebola is causing high mortality rates in persons over the age of 45 years (> 90 percent death rate). It is around 50% for younger adults, and more favorable for children. This would explain why the older missionaries who went to Spain with Ebola died, but their nurse did not. Likewise, the health care workers from the USA who have had Ebola and then recovered, were younger adults.
ReplyDeleteOf course, good treatment and a proactive diagnosis also also positive factors. The people in the USA and Europe who got Ebola were receiving excellent supportive care.
Pete, Redondo Beach