Rickettsioses in Swedish travellers, 1997-2001.

From laboratory records, information was collected on all 77 cases of rickettsioses diagnosed in Sweden during 1997 - 2001, 14 of which were diagnosed as belonging to the typhus group and 63 to the spotted fever group. Signs of hepatic involvement occurred more frequently in the typhus group. Denominators for the number of journeys to different parts of the world were retrieved from a commercial Swedish tourist database. The estimated risk of rickettsioses in destinations outside Europe varied from 1 case in 140 000 travellers to south-east Asia to 1 in 1600 travellers to southern Africa. The risk of infection in southern Africa increased over the 5 y period and is now 4 - 5 times higher than the risk of acquiring malaria in the same region. Rickettsiosis is an important differential diagnosis to consider in the febrile traveller, especially from South Africa. It should be remembered that the serological response may be considerably delayed and in patients with a negative first serology, serological testing should be repeated. Where there is a strong suspicion of rickettsiosis treatment may have to be started without a confirmed diagnosis.