Migration-associated malaria from Africa in southern Spain

Epidemiological characteristics and molecular identification of Plasmodium species among cases of imported malaria in Kuwait during the COVID-19 pandemic

Cases of imported malaria are reported each year in several malaria non-endemic countries, including Kuwait. PCR testing is the ideal method for identification of the infecting Plasmodium spp. The present study documented the epidemiologic characteristics of molecularly confirmed cases of imported malaria in Kuwait during the first year of COVID-19 pandemic. During the period from February 2020 to February 2021, 100 travelers with suspected malaria who had come from malaria-endemic countries of Africa (n = 60) and Asia (n = 40) were examined. Malaria diagnosis was made by microscopy of blood-stained smears and confirmed by a multiplex real-time PCR assay. Samples with discordant species identification results were sequenced. A total of 27 cases (27%) [P. falciparum, 14; P. vivax, 11; P. ovale, 1; mixed P. falciparum and P. malariae, 1] were detected, of whom 12 came to Kuwait for the first time and 15 were returning after visiting their home countries. Most of the returning travelers (12 out of 15 cases, 80%) had not received malaria chemoprophylaxis. Most cases of falciparum malaria (13/15) were Africans while most of the vivax cases (9/11) were Asians. Malaria was more common among subjects entering Kuwait for the first time (OR = 4.025, CI 1.07,15.1) and illiterates (OR = 13.8, CI 1.8,101.4). In conclusion, imported malaria caused mainly by P. falciparum and P. vivax was an ongoing problem during the COVID-19 pandemic. Travel history and education level were significant predictors of malaria among suspected cases.

Molecular detection of sub-microscopic infections and Plasmodium falciparum histidine-rich protein-2 and 3 gene deletions in pre-elimination settings of South Africa

South Africa's efforts toward eliminating malaria have positioned the country in the pre-elimination stage. Imported and sub-microscopic cases still contribute to the persistence of malaria in regions of low transmission as identified in this study where diagnostics is built largely on the use of Rapid Diagnostic Test (RDT). However, the presence of Pfhrp2/3 gene deletion is known to interfere with the accuracy of diagnosis with the use of RDT. Malaria elimination and detection of Pfhrp2/3 gene deletion in the pre-elimination setting requires accurate molecular surveillance. With the core objective of this study being the determination of the presence sub-microscopic malaria cases and deleted Pfhrp2/3 gene markers, a total of 354 samples were collected from five districts of KwaZulu Natal, South Africa. These samples were prepared for molecular analysis using primers and PCR conditions specific for amplification of 18S rRNA and msp-1gene. Positive amplicons were analysed for the presence of Pfhrp2/3 and flanking genes, along with Sanger sequencing and phylogenetic studies. Out of 354 samples collected 339 were tested negative with PfHRP2 based RDTs. Of these Pfhrp2 and Pfhrp3 gene deletions were confirmed in 94.7% (18/19) and 100% (19/19) respectively. High migration rate (75%) among the study participants was noted and phylogenetic analysis of sequenced isolates showed close evolutionary relatedness with India, United Kingdom, Iran, and Myanmar and China isolates. Molecular-based test is recommended as an essential surveillance tool for malaria management programs as the target focuses on elimination.

Malaria among members of the U.S. Armed Forces, 2023

MSMR publishes annual updates on the incidence of malaria among U.S. service members. Malaria infection remains a potential health threat to U.S. service members located in or near endemic areas due to duty assignment, participation in contingency operations, or personal travel. In 2023, a total of 39 active and reserve component service members were diagnosed with or reported to have malaria, an 8.3% increase from the 36 cases identified in 2022. Over half of the malaria cases in 2023 were caused by Plasmodium falciparum (53.8%; n=21) followed by unspecified types of malaria (35.9%; n=14) and P vivax and other Plasmodia (5.1%; n=2 each ). Malaria cases were diagnosed or reported from 22 different medical facilities: 18 in the U.S., 2 in Germany, 1 in Africa, 1 in South Korea. Of the 33 cases with known locations of diagnoses, 6 (18.2%) were reported from or diagnosed outside the U.S.

Estimation of parasitaemia in imported falciparum malaria using the results of a combined rapid diagnostic test. No big help from haematological parameters

BACKGROUND

Microscopy continues to be the mainstay for the evaluation of parasitaemia in malaria but requires laboratory support and microbiological experience. Other fast and simple methods are necessary.

METHODS

A retrospective observational study of imported malaria treated from July-2007 to December-2020 was carried out to evaluate the association between the degree of parasitaemia and both rapid diagnostic tests (RDT) reactivity patterns and haematological parameters. Plasmodium falciparum monoinfections diagnosed by peripheral blood smear and/or polymerase chain reaction (PCR),which also had a positive RDT result in the same blood sample, were included in the study.

RESULTS

A total of 273 patients were included. Most of them were male (n = 256; 93.8%) and visiting friends and relatives (VFR) travellers (n = 252; 92.3%). Patients with plasmodial lactate dehydrogenase (pLDH) or aldolase and histidine-rich protein 2 (HRP-2) co-reactivity (Pan/Pf pattern) had a parasitaemia range between 0 and 37% while those with just HRP-2 reactivity (P. falciparum pattern) had ranges between 0 and 1%. Not a single case of P. falciparum pattern was found for parasitaemia ranges greater than 1%, showing a negative predictive value of 100% for high parasitaemia. All the correlations between haematological parameters and parasitaemia resulted to be weak, with a maximum rho coefficient of -0.35 for lymphocytes and platelets, and of 0.40 for neutrophils-to-lymphocytes count ratio. Multivariate predictive models were constructed reflecting a poor predictive capacity.

CONCLUSIONS

The reactivity pattern of RDT allows a rapid semi-quantitative assessment of P. falciparum parasitaemia in travellers with imported malaria, discriminating patients with lower parasite loads. Haematological parameters were not able to estimate parasitaemia with sufficient precision.

Screening of imported malaria infection in asymptomatic migrants from Sub-Saharan Africa: A retrospective analysis of a 2010-2019 cohort

BACKGROUND

Up to 40% of cases of imported malaria in Europe are diagnosed in recently arrived migrants, who generally exhibit asymptomatic or mild symptoms and show low parasitaemia (submicroscopic). The study describes the prevalence of malaria infection among asymptomatic Sub-Saharan African migrants (ASSAM) and compares asymptomatic malaria-infected (AMI) vs non-malaria infected patients.

METHODS

An observational, comparative, retrospective study was carried out in ASSAM who underwent a medical examination, between 2010 and 2019 at the National Reference Unit for Tropical Diseases (NRU-Trop) in Madrid, Spain. Medical examination and systematic screening protocol for infectious diseases, including screening for malaria infection by Polymerase Chain Reaction (PCR) was performed.

RESULTS

During the study period, 632 out of 1061 ASSAM were screened for malaria, median age: 24 years (IQR:1-5); median time from arrival to diagnosis: 2 months (IQR:1-5). P. falciparum was the most frequent species: 61 patients (67.8%). Compared to non-malaria infected, AMI subjects had: higher rate of co-infection with S. stercoralis (41.1%VS 22.9%;p < 0.001) and filariae (8.9% VS 2.4%;p = 0.006), lower erythrocyte corpuscular volume (83.6 VS 84.4;p = 0.008) and lower levels of cholesterol (151.0 VS 167.3;p < 0.001).

CONCLUSIONS

We observed a high prevalence of AMI among ASSAM. This highlights the need to consider routing screening of migrants from endemic areas and to study if such screening could avoid the potential morbidities associated with chronic infection, reduce morbi-mortality of acute malaria and the risk of transmission in host communities.