Imported submicroscopic malaria in Madrid

Abstract

BackgroundSubmicroscopic malaria (SMM) can be defined as low-density infections of Plasmodium that are unlikely to be detected by conventional microscopy. Such submicroscopic infections only occasionally cause acute disease, but they are capable of infecting mosquitoes and contributing to transmission. This entity is frequent in endemic countries; however, little is known about imported SMM.The goals of this study were two-fold: a) to know the frequency of imported SMM, and b) to describe epidemiological, laboratorial and clinical features of imported SMM.MethodsA retrospective study based on review of medical records was performed. The study population consisted of patients older than 15 years attended at the Tropical Medicine Unit of Hospital Carlos III, between January 1, 2002 and December 31, 2007. Routinely detection techniques for Plasmodium included Field staining and microscopic examination through thick and thin blood smear. A semi-nested multiplex malaria PCR was used to diagnose or to confirm cases with low parasitaemia.ResultsSMM was diagnosed in 104 cases, representing 35.5% of all malaria cases. Mean age (IC95%) was 40.38 years (37.41-43.34), and sex distribution was similar. Most cases were in immigrants, but some cases were found in travellers. Equatorial Guinea was the main country where infection was acquired (81.7%). Symptoms were present only in 28.8% of all SMM cases, mainly asthenia (73.3% of symptomatic patients), fever (60%) and arthromialgias (53.3%). The associated laboratory abnormalities were anaemia (27.9%), leukopaenia (15.4%) and thrombopaenia (15.4%). Co-morbidity was described in 75 cases (72.1%).ConclusionsResults from this study suggest that imported SMM should be considered in some patients attended at Tropical Medicine Units. Although it is usually asymptomatic, it may be responsible of fever, or laboratory abnormalities in patients coming from endemic areas. The possibility of transmission in SMM has been previously described in endemic zones, and presence of vector in Europe has also been reported. Implementation of molecular tests in all asymptomatic individuals coming from endemic area is not economically feasible. So re-emergence of malaria (Plasmodium vivax) in Europe may be speculated.

Clinical significance of molecular methods in the diagnosis of imported malaria in returning travelers in Serbia

“…Malaria was predominantly imported from Africa, as in other European countries. 4,5,[11][12][13] However, in contrast to these previous reports, 11,13 for 86.7% of patients in the present study, this was not the first attack, in comparison to, for example, only 17.8% in Slovenia, and a vast majority of patients did not take any prophylaxis. Moreover, nearly a third of the patients had started antimalarial treatment before presentation.…”

“…The dominant mode of importing malaria in Serbia has always been by Serbian workers hired at construction sites in malaria endemic areas, 6,7 where many stay for more than 6 months; in contrast, in Western Europe malaria mostly occurs in immigrants and tourists. 5,12 SMM was registered in 6.7% of patients, all of whom had started treatment before presentation at the hospital. A study in Madrid showed 35.5% cases of SMM, which was attributed to immunity in a large proportion of immigrants from endemic regions.…”

“…A study in Madrid showed 35.5% cases of SMM, which was attributed to immunity in a large proportion of immigrants from endemic regions. 5 The dominant species in this study was P. falciparum. Although this species commonly causes higher parasitemia, parasitemia was generally low in our series on account of the high proportion of patients who had already started treatment before diagnosis.…”

“…This has been overcome by molecular methods, which are constantly being improved for increased sensitivity and specificity. [2][3][4][5] The World Health Organization (WHO) officially declared Serbia (then within Yugoslavia) malaria-free in 1974; only imported cases have occurred ever since. From 1975From to 1988 to 57 cases of imported malaria were reported per year.…”

LAMP kit for diagnosis of non-falciparum malaria in Plasmodium ovale infected patients

“…On the other hand, the growth in international travel and migration has increased the incidence of imported malaria cases in developed countries. In Spain, submicroscopic malaria is common in sub-Saharan migrants (up to 35.5% in one series [6]) and Plasmodium ovale infection may represent up to 8% of imported malaria cases, as shown in some published series of mainly West African patients [7]. Therefore, sensitive molecular tools are needed both for malaria control programmes and for detecting with certainty malaria imported cases in patients returning from P. ovale endemic areas.…”