Severity of Plasmodium falciparum and Non-falciparum Malaria in Travelers and Migrants: A Nationwide Observational Study Over 2 Decades in Sweden

Abstract

Background The aim was to assess factors affecting disease severity in imported P. falciparum and non-falciparum malaria. Methods We reviewed medical records from 2793/3260 (85.7%) of all episodes notified in Sweden between 1995 and 2015 and performed multivariable logistic regression. Results 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 <5 years and >40 years, origin in nonendemic 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 >60 years, 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. Conclusions 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 nonendemic areas.

Plasmodium vivax severe imported malaria in two migrants in France

“…The current World Health Organization criteria for severe forms of malaria include hyperbilirubinaemia with a threshold > 50 mmol/L [13,14]. We agree with other authors that hyperbilirubinaemia, when isolated, does not seem to be a suitable criterion for imported severe malaria [11]. At his third visit, as patient 2 developed a severe episode, the bilirubinaemia was slightly above the threshold (52 mmol/L).…”

“…According to the current literature, imported malaria episodes due to other species than P. falciparum usually do not evolve towards the death of travellers [11,16], but in some instances they may have led to serious complications and important residual damages [17]. As their condition deteriorated, both patients presented here were rapidly admitted in ICU where they received appropriate treatments.…”

“…Both patients suffered from septic shock, which is a criterion frequently reported for P. vivax severe malaria [7,11,12]. Patient 2 showed a marked hyperbilirubinaemia (102 mmol/L) on his first visit as a clinically uncomplicated malaria episode was diagnosed.…”

Influx of diverse, drug resistant and transmissible Plasmodium falciparum into a malaria-free setting in Gulf Cooperation (GCC) countries.

“…Asymptomatic infection can often develop into clinical malaria after as long as 8 years of settlement in a malaria-free country [34]. Unlike P. falciparum, P. vivax includes persistent liver stages (hypnozoites) that permit dormant infection, and can lead to a relapse within a 9-year period [35]. Therefore, asymptomatic migrants with malaria parasites can maintain a long-lasting reservoir for secondary local transmission in receptive malaria-free areas,…”

Plasmodium vivax severe imported malaria in two migrants in France

“…P. vivax is increasingly recognized as responsible for severe malaria in endemic areas and also in imported malaria [8,9]. In a recent retrospective study conducted in Sweden, Wangdahl et al…”