Differential Prevalences of Pfmdr1 Polymorphisms in Symptomatic and Asymptomatic Plasmodium falciparum Infections in Lastoursville: A Rural Area in East-Central Gabon

Asymptomatic Malaria Infection and Hidden Parasitic Burden in Gabonese Schoolchildren: Unveiling Silent Co-Infections in Rural and Urban Settings

This study aimed to determine the prevalence of co-infection with malaria and intestinal parasites and assess its association with anemia in school-aged children from rural and urban settlements in Gabon. This cross-sectional study involved afebrile school children recruited at schools between May and June 2021. Blood and stool samples were collected from participants whose parents or legal guardians provided informed consent to participate in the study. Hemoglobin concentration (Hb) was measured using a HemoCue photometer (HemoCue 201, HemoCue, Angelholm, Sweden). Giemsa-stained blood films were examined to detect malaria parasites and any filarial infections, while the merthiolate-iodine concentration (MIC) method was used to identify intestinal parasitic infections (IPI). A total of four hundred and seventy (470) school-aged children were successfully enrolled in this study. The observed prevalence values were as follows: malaria infection at 69.6%, IPIs at 19.1%, filaria at 5.1%, Schistosoma infection at 15.0%, and anemia at 29.0%. Co-infections of malaria with IPIs, filaria, and Schistosoma were present in 12.3%, 4.7%, and 6.6% of the children, respectively. Malaria and filaria infections were associated with residing in Lastourville city (p < 0.05) and were also correlated with age (p < 0.05), whereas IPIs were associated with male gender and living in the city of Lastourville. Anemia was linked to malaria infection (p < 0.05) and was more prevalent among children living in rural areas. The findings of this study indicate that malaria, IPIs, and Schistosoma infections continue to pose a significant public health problem in the study area, even though only malaria infection appeared to be associated with anemia. Nevertheless, these results highlight the need for implementing control measures to reduce the prevalence of malaria, IPIs, filaria, and Schistosoma, particularly in Lastourville.

Epidemiology of malaria in Gabon: A systematic review and meta-analysis from 1980 to 2023

The objective of this were conducted to elucidate spatiotemporal variations in malaria epidemiology in Gabon since 1980. For that, five databases, were used to collect and identify all studies published between 1980 and 2023 on malaria prevalence, antimalarial drug resistance, markers of antimalarial drug resistance and insecticide resistance marker. The findings suggest that Gabon continues to face malaria as an urgent public health problem, with persistently high prevalence rates. Markers of resistance to CQ persist despite its withdrawal, and markers of resistance to SP have emerged with a high frequency, reaching 100 %, while ACTs remain effective. Also, recent studies have identified markers of resistance to the insecticides Kdr-w and Kdr-e at frequencies ranging from 25 % to 100 %. Ace1R mutation was reported with a frequency of 0.4 %. In conclusion, the efficacy of ACTs remains above the threshold recommended by the WHO. Organo-phosphates and carbamates could provide an alternative for vector control.

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

BACKGROUND

The emergence and spread of Plasmodium falciparum parasites resistant to antimalarial drugs constitutes an obstacle to malaria control and elimination. This study aimed to identify the prevalence of polymorphisms in pfk13, pfmdr1, pfdhfr, pfdhps and pfcrt genes in isolates from asymptomatic and symptomatic school-age children in Kinshasa.

METHODS

Nested-PCR followed by sequencing was performed for the detection of pfk13, pfmdr1, pfdhfr, pfdhps and pfcrt polymorphisms.

RESULTS

Two mutations in pfk13, C532S and Q613E were identified in the Democratic Republic of Congo for the first time. The prevalence of the drug-resistance associated mutations pfcrt K76T, pfdhps K540E and pfmdr1 N86Y was low, being 27%, 20% and 9%, respectively.

CONCLUSION

We found a low prevalence of genetic markers associated with chloroquine and sulfadoxine-pyrimethamine resistance in Kinshasa. Furthermore, no mutations previously associated with resistance against artemisinin and is derivatives were observed in the pfK13 gene. These findings support the continued use of ACTs and IPTp-SP. Continuous molecular monitoring of antimalarial resistance markers is recommended.