WHO Assurances Rely on Data from Milder Marburg Outbreaks
Recombinomics Commentary
April 1, 2005
>> Ms Chaib said Marburg was regarded as "a little less severe than Ebola because the chain of transmission is shorter".
The virus can be passed on to four people on average, while Ebola is more resistant and can be passed on to 12 more victims.
Secondary transmission of Marburg is also less severe than the initial case, she added. <<
How Marburg was regarded in the past may have little bearing on the current outbreak. Usually Ebola is found in this region of Africa, so the current Marburg strain could have recombined with Ebola to acquire enhanced lethality and transmissibility factors.
Regardless of the mechanism, the virus has caused a record number of deaths and has a case fatality rate of 100%. Moreover, the virus appears to be changing. Initially it was killing children predominantly. The first health care worker died in March, and she was quickly followed by 11 others who have died over a two week time frame. Thus, the precautions used in the past to prevent transmission to healthcare workers and their failure has now produced a string of deaths among health care workers and first responders.
Passage of the virus is also dependent on conditions, and since the transmissibility of the virus has improved recently, early data on the outbreak may have little relevance.
The task of identifying victims is also difficult. When WHO identified Marburg on March 23 there were 95 deaths. Now there are 132, creating a large number of contacts for known deaths. However, some of the most recent deaths were in residential neighborhoods, which suggest many more fatalities and infected contacts will be found. Citizens are being urged to call in deaths, demonstrating the lack of effective contact tracing at this time.
Thus, while Marburg can be brought under control at some time, the size and logistics associated with the current outbreak suggest it will be more challenging than prior outbreaks.
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