Ebola and diseases mimicking most of its symptoms are so widespread in Liberia as to vitiate precise identification of Ebola exposures from individual infecteds. That someone develops Ebola 32 days after a known exposure might be due instead to a more recent unsuspected exposure.
This is less of a problem outside Liberia, but in Guinea and Sierra Leone there are enough Ebola victims that the latent but infectious carrier threat makes precise identification of exposure dates difficult to ascertain.
The fomite infection possibility creates major problems in ascertaining precise infection date data in urban areas. This will become especially so in areas with significantly less sunlight than West Africa, but fortunately there have been relatively few such threats to date.
All of this uncertainty does make the 21-day rule more plausible, though.
Via the PFIF
The Malian government has confirmed the first case of Ebola in the country.
It said a two-year-old girl had tested positive for the haemorrhagic virus. Reports say she recently returned from the neighbouring Guinea....