Severity of Plasmodium falciparum and non-falciparum malaria in travelers and migrants: a nationwide observational study over two decades in Sweden.
The aim was to assess factors affecting disease severity in imported P. falciparum and non-falciparum malaria.
We reviewed medical records from 2793/3260 (85.7%) of all episodes notified in Sweden between 1995 and 2015 and performed multivariable logistic regression.
Severe malaria according to WHO 2015 criteria was found in P. falciparum (9.4%), P. vivax (7.7%), P. ovale (5.3%), P. malariae (3.3%) and mixed P. falciparum episodes (21.1%). Factors associated with severe P. falciparum malaria were age <5y and >40y, origin in non-endemic country, pregnancy, HIV, region of diagnosis and health care delay. Moreover, oral treatment of P. falciparum episodes with parasitemia ≥2% without severe signs at presentation was associated with progress to severe malaria with selected criteria. In non-falciparum, age >60y, health care delay and endemic origin were identified as risk factors for severe disease. Among patients originating in endemic countries, a higher risk for severe malaria, both P. falciparum and non-falciparum, was observed among newly arrived migrants.
Severe malaria was observed in P. falciparum and non-falciparum episodes. Current WHO criteria for severe malaria may need optimization to better guide the management of malaria of different species in travelers and migrants in non-endemic areas.