For scientists tracking the deadly Ebola virus in West Africa, it’s not about complex virology and genotyping, but about how contagious microbes – like humans – use planes, bikes and taxis to spread.

So far, authorities have taken no action to limit international travel in the region. The airlines association IATA said yesterday that the World Health Organisation is not recommending any such restrictions or frontier closures.

However, tracing every person who may have had contact with an infected case is vital to getting on top of the outbreak within West Africa, and doing so often means teasing out seemingly routine information about victims’ lives.

In Nigeria, which had an imported case of the virus in a Liberian-American who flew to Lagos this week, authorities will have to trace all passengers and anyone else he may have crossed paths with to avoid the kind of spread other countries in the region have suffered.

Tracing all contacts of infected cases vital for control

The West Africa outbreak, which began in Guinea in February, has already spread to Liberia and Sierra Leone. With more than 1,200 cases and 672 deaths, it is the largest since the Ebola virus was discovered almost 40 years ago.

Sierra Leone has declared a state of public emergency to tackle the outbreak, while Liberia is closing schools and considering quarantining some communities.

“The most important thing is good surveillance of everyone who has been in contact or could have been exposed,” said David Heymann, a professor of infectious disease epidemiology and head of global health security at Britain’s Royal Institute of International Affairs.

The spread of this outbreak from Guinea to Liberia in March shows how tracing even the most routine aspects of peoples’ lives, relationships and reactions will be vital to containing Ebola’s spread.

The original case in that instance is believed by epidemiologists and virus experts to have been a woman who went to a market in Guinea before returning, unwell, to her home village in neighbouring northern Liberia.