Dr. Mike Ryan is managing WHO's response from Geneva. He said that: "The cases counted so far don't include victims who died outside hospitals. Some WHO experts expect a doubling of the current toll. That would make this Angolan outbreak the largest Marburg epidemic ever...and larger than almost any Ebola [hemorrhagic fever] outbreak. This is particularly worrying becuase the only hospital in the regional capital at the centre of the outbreak was closed last week. So expect a report where the number of deaths jumps sharply. And that will get peoples attention for something is still at the periphery for most people.
If the current toll is doubled by deaths outside of hospitals, then the outbreak in Angola would be the largest on record for hemorrhagic fever by Marburg or Ebola. The current record is 280 deaths in 1976 by Ebola in Zaire (Democratic Republic of Congo). There are now over 150 cases and over 140 deaths, but there have been no reported recoveries, so the case fatality rate is still at 100%. The cases outside of hospitals will almost certainly lead to another round of infections. In the past several weeks the demographics have changed. There have been at least 12 heath care workers who have died. Prior to last month there were no reported health care worker deaths and 75% of the deaths were children under 5. Marburg has now moved into the adult population and spread to 4 province. There are also suspect cases in the Democratic Republic of Congo and 9 patients are under hospital quarantine in Italy. Another 16 are under hospital quarantine in Cabinda, and there have now been several deaths in Luanda, although all of the initial deaths link back to Uige.
The current outbreak in Angola is particularly virulent, eventually killing all infected patients. There is little evidence to support a more limited transmission. Marburg is killing quicker and at a higher death rate than Ebola. The is a good possibility that Marburg has recombined and picked up some additional genetic information that is leading to this high case fatality rate and rapid spread. I still think this a limited risk for developed countries but could devastate Africa and parts of Asia.