Identification of polymorphisms in genes associated with drug resistance in Plasmodium falciparum isolates from school-age children in Kinshasa, Democratic Republic of Congo

Abstract Background. Loss of efficacy of malaria diagnostic tests may lead to untreated or mistreated cases, compromising case management and control. There is an increasing reliance on rapid diagnostic tests (RDTs), with the most widely used of these targeting the Plasmodium falciparum histidine-rich protein 2 gene. There are numerous reports of the deletion of this gene in P. falciparum parasites in some populations, rendering them undetectable by PfHRP2 RDTs. We aimed to identify P. falciparum parasites lacking the P. falciparum histidine rich protein 2 and 3 genes isolated from asymptomatic and symptomatic school-age children in Kinshasa, Democratic Republic of Congo. Methods. We assessed the performance of PfHRP2-based RDTs in comparison to microscopy and PCR. PCR was then used to identify parasite isolates lacking pfhrp2/3 genes. Results. Of 462 DNA samples analysed, deletions of the pfhrp2 and pfhrp3 genes were found in only three (2%) samples and one (1%) sample in the RDT positive subgroup, respectively. No parasites lacking the pfhrp2/3 genes were found in the RDT negative subgroup. Conclusion. Plasmodium falciparum histidine-rich protein 2/3 gene deletions are uncommon in the surveyed population, and do not result in diagnostic failure. We encourage the use of rigorous PCR methods to identify pfhrp2/3 gene deletions in order to minimize the overestimation of their prevalence.

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Malaria Parasite Species Composition of Plasmodium Infections Among Asymptomatic and Symptomatic School-Age Children in Rural and Urban Areas of Kinshasa, Democratic Republic of Congo

10.21203/rs.3.rs-389568/v1 ◽

2021 ◽

Author(s):

Sabin S. Nundu ◽

Richard Culleton ◽

Shirley V. Simpson ◽

Hiroaki Arima ◽

Jean-Jacques Muyembe ◽

...

Keyword(s):

Urban Area ◽

Rural Area ◽

Malaria Parasite ◽

Parasite Species ◽

Democratic Republic ◽

Democratic Republic Of Congo ◽

School Age Children ◽

Asymptomatic Malaria ◽

School Age ◽

Republic Of Congo

Abstract Background. Malaria remains a major public health concern in Democratic Republic of Congo (DRC), and school-age children are relatively neglected in malaria prevalence surveys and may constitute a significant reservoir of transmission. This study aimed to understand the burden of malaria infections in school-age children in Kinshasa/DRC.Methods. 634 (427 asymptomatic and 207 symptomatic) blood samples were collected from a cross-sectional survey of school-age children aged 6 to 14 years both without and with malaria symptoms. Nested-PCR was performed for malaria parasite species typing. Results. The overall prevalence of Plasmodium spp., Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale was 62.3, 58.1, 19.9 and 10.8% among asymptomatic whereas it was 94.4, 93.2, 12.6 and 15.9% in symptomatic children, respectively. All Plasmodium species infections were significantly more prevalent in the rural area compared to the urban area in asymptomatic infections (p<0.001). Living in a rural as opposed to an urban area was associated with a five-fold greater risk of asymptomatic malaria parasite carriage (p<0.001). Amongst asymptomatic malaria parasite carriers, 43% of children in the rural area were co-infected with two or more species with P. falciparum + P. malariae the most common (24%) whereas in the urban setting, fewer children carried co-infections (16%) with P. falciparum + P. malariae again the most common (9%). A fifth of rural-dwelling symptomatic children were co-infected with two or more species with P. falciparum + P. ovale the most common (14%), while a quarter of symptomatic children in the urban area carried multiple species, with co-infections of P. falciparum + P. malariae the most common (11%). Conclusion. School-age children are at significant risk from both asymptomatic and symptomatic malaria parasite infections. Continuous systematic screening and treatment of school-age children in high-transmission settings across the country may reinforce malaria intervention measures.

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Malaria parasite species composition of Plasmodium infections among asymptomatic and symptomatic school-age children in rural and urban areas of Kinshasa, Democratic Republic of Congo

Malaria Journal ◽

10.1186/s12936-021-03919-4 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Sabin S. Nundu ◽

Richard Culleton ◽

Shirley V. Simpson ◽

Hiroaki Arima ◽

Jean-Jacques Muyembe ◽

...

Keyword(s):

Urban Area ◽

Urban Areas ◽

Malaria Parasite ◽

Democratic Republic ◽

Democratic Republic Of Congo ◽

School Age Children ◽

Asymptomatic Malaria ◽

School Age ◽

Republic Of Congo ◽

Symptomatic Malaria

Abstract Background Malaria remains a major public health concern in the Democratic Republic of Congo (DRC), and school-age children are relatively neglected in malaria prevalence surveys and may constitute a significant reservoir of transmission. This study aimed to understand the burden of malaria infections in school-age children in Kinshasa/DRC. Methods A total of 634 (427 asymptomatic and 207 symptomatic) blood samples collected from school-age children aged 6 to 14 years were analysed by microscopy, RDT and Nested-PCR. Results The overall prevalence of Plasmodium spp. by microscopy, RDT and PCR was 33%, 42% and 62% among asymptomatic children and 59%, 64% and 95% in symptomatic children, respectively. The prevalence of Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale spp. by PCR was 58%, 20% and 11% among asymptomatic and 93%, 13% and 16% in symptomatic children, respectively. Among P. ovale spp., P. ovale curtisi, P. ovale wallikeri and mixed P. ovale curtisi + P. ovale wallikeri accounted for 75%, 24% and 1% of infections, respectively. All Plasmodium species infections were significantly more prevalent in the rural area compared to the urban area in asymptomatic infections (p < 0.001). Living in a rural as opposed to an urban area was associated with a five-fold greater risk of asymptomatic malaria parasite carriage (p < 0.001). Amongst asymptomatic malaria parasite carriers, 43% and 16% of children harboured mixed Plasmodium with P. falciparum infections in the rural and the urban areas, respectively, whereas in symptomatic malaria infections, it was 22% and 26%, respectively. Few children carried single infections of P. malariae (2.2%) and P. ovale spp. (1.9%). Conclusion School-age children are at significant risk from both asymptomatic and symptomatic malaria infections. Continuous systematic screening and treatment of school-age children in high-transmission settings is needed.

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