Deutsche Welle: According to the Robert-Koch-Institute for infectious diseases, the number of tuberculosis (TB) cases in Germany has gone up, recently - from 4,533 in 2014 to 5,865 last year. Can this increase be attributed to the refugee influx?

Dr. Karl Schenkel: The refugees are contributing to this. We have taken in a large number of refugees, and right now, we are detecting a linear increase in infections. But that's something we did expect - we are not surprised by this.

How can one detect tuberculosis among refugees?

Here in Germany, we used to conduct regular screenings for tuberculosis. Then they were abolished, because as the numbers of infections were going down, it was not considered necessary screen everyone anymore. Now, we have partly reinstituted regular screenings - which are mandated under German federal law.

The law stipulates that people who are put up in mass accommodation, such as refugee camps, must be free of infectious diseases, including TB. All adults and teenagers over the age of 15 years will have their lungs x-rayed. Pregnant women are, of course, an exception.

Is the risk of transmission higher among refugees?

The key to fighting TB is its early detection. This means that people have to be x-rayed as soon as they arrive in Germany. If TB is found, these patients will have to be isolated in special clinics.

This is the only way to break the chain of infection and to ensure that other people in the camps people are not be infected. The risk of infection among refugees in mass accomodation is fairly high because there are many people in close quarters. The more people living in poor conditions - and often with bad nutrition - the higher the risk that TB will be passed on from one person to the next.

Is there a danger that in the future we will see considerably higher numbers of TB than a few years ago?

Well, we know that TB is mainly transmitted within communities, such as in a household or family. Tuberculosis is not as infectious as, for example, viral infections like measles, chicken pox or ebola. Transmission is - in principle - possible when travelling on a crowded bus with someone who has TB. But it is much more likely that a person gets infected by living in the same household with an infected person over the course of hours, days or weeks.

Which of the countries of origin have the highest numbers of TB cases?

One has to look at each country separately: There are a lot of TB cases in Afghanistan. In Syria there are fewer. However, one has to note, that the most recent figures of the World Health Organisation (WHO) are from before the war.

And then one has to consider the conditions during the refugees' flight. On the Balkan route people are living in crowded camps and facilities. Of course, the danger of infection rises considerably over the course of weeks and months. Children are much more vulnerable than adults.

All of this means that we can expect a further rise in cases and we have to step up our efforts in strengthening the public health services.

Gudrun Heise conducted the interview

Dr. Karl Schenkel is pneumologist and works as an adviser to patients at the German Central Committee for the Fight against Tuberculosis (DZK). The DZK was founded in 1895 in Berlin, to counter the spread of what was then a deadly and widespread epidemic.