Epidemiologic situation

There have been some imported cases outside of Africa, though not many. Individual cases are usually related to international travel, and there have also been some localised outbreaks. For example, there were 47 cases in the United States in 2003, but these were related to people who had been in contact with infected rodents imported from Africa.

The appearance of a growing number of cases in recent weeks, first detected in the United Kingdom, and then in other EU countries (including Spain), the US and Canada has led to a health alert.

The initial phase of an epidemiological study is in progress to understand how these cases have occurred, as well as to find out their transmission chains and associated risk factors.  

For now, everything points to community transmission occurring undetected for a few weeks. Then, after the alert was given, it has led to more cases being identified every day.

It is also considered that the disease could be more widespread in Africa than previously believed, and this may have facilitated the importation of cases.