With the details given I'm with Jermyn and given that Kenya has no known cases of ebola I would have to side with him that asking the teacher to sit out was illogical.
"The World Health Organization classified Kenya as a high-risk area for transmission of the deadly Ebola virus on Wednesday, as Sierra Leone reported that a second leading physician has died of the disease.
Even though there have been no reported cases of Ebola in Kenya, the country’s role as a transportation hub in East Africa makes it more vulnerable to the disease, WHO said."
http://www.voanews.com/content/germa...k/2411822.html
A bit outdated (given it was in August) but was the best I could find. Still Kenya is a far bit away from the countries affected by ebola. There is some risk there due to its role as a transportation hub but nothing else to really worry about.