Burden of asymptomatic malaria in adult sub-Saharan migrants attending an outpatient clinic in Rome from February 2024 to January 2025
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Background
Sub-Saharan African (SSA) migrants may carry asymptomatic Plasmodium infections after leaving endemic regions, potentially posing public health challenges in host countries. However, data on the prevalence and persistence of infection after migration are currently limited. The objective of this study is to assess the burden of asymptomatic malaria among adult SSA migrants attending an outpatient clinic in Rome.
Methods
Between February 2024 and January 2025, SSA migrants attending the Lazzaro Spallanzani Institute’s mobile population clinic in Rome, Italy were screened for malaria using rapid diagnostic tests (RDTs), loop-mediated isothermal amplification (LAMP), thick smears, and real-time polymerase chain reaction (RT-PCR). Eligibility criteria included age ≥ 16, absence of fever, and origin or transit through malaria-endemic regions. Descriptive statistics were used to summarize epidemiological, clinical, and laboratory data. Continuous variables were expressed as means ± SD or median (IQR), and categorical variables as counts and percentages. A P -value < 0.05 was considered significant.
Results
Among 87 asymptomatic migrants, malaria prevalence was 6%, all in male SSA migrants. One mixed infection was confirmed by microscopy. LAMP detected Plasmodium spp. in 5 cases (6.0%), confirmed by RT-PCR, while RDT identified only 2 (2.3%). Species identified by RT-PCR included P. falciparum , P. malariae , P. ovale , and one mixed infection. The longest time since arrival among positives was 181 days; including detention in Libya, the median interval since departure from endemic areas exceeded 600 days.
Conclusions
Asymptomatic malaria can last for months after arrival and is often missed by RDTs. Incorporating RT-PCR diagnostics into routine screenings can improve early detection, lower local transmission risk, and enhance health outcomes.
