Abstract
BACKGROUND: Leishmaniasis is endemic in many countries worldwide, with a prevalence of 12 million people infected, and an estimated annual incidence of 500 000 visceral leishmaniasis cases. In Europe visceral leishmaniasis is considered endemic mainly in the Mediterranean countries and cases in non-endemic European countries north of the Alps have primarily been reported in returning travellers. The incubation period is typically described between 6 weeks to 6 months. The cases presented highlight the occurrence of longer incubation periods and illustrate the individual variability for progression from infection to disease. CASE PRESENTATION: We report the cases of 18-months-old twin girls living at the German-Swiss border, who developed visceral leishmaniasis 7 and 15 months after travelling to Tuscany. They presented with fever of unknown origin and pancytopenia. Both had splenomegaly and in the first case haemophagocytic lymphohistiocytosis or leukaemia was initially included in the differential diagnosis. Diagnosis of visceral leishmaniasis was confirmed by presence of intracytoplasmic localised leishmania parasites on bone marrow aspirate and/or positive leishmania serology. Both girls responded well to treatment with liposomal amphotericin B. The mother and two older siblings remained uninfected, while the father was diagnosed to be an asymptomatic carrier. CONCLUSION: Visceral leishmaniasis is an important differential diagnosis for fever of unknown origin and pancytopenia in young children living in countries with endemic disease and highlights the importance of obtaining a detailed travel history. Hemophagocytic lymphohistiocytosis and acute leukaemia present with similar symptoms and consequently are important differential diagnoses. Factors determining progression from infection to disease are not fully understood but younger age seems to be an important risk factor. Screening of siblings from affected individuals therefore may be warranted.