Entomological drivers of uneven malaria transmission in urban lowland areas in Bouaké, Côte d’Ivoire

Dahoui, Milossé M. C.; Adou, Kouassi A.; Coulibaly, Bamoro; Niamien, Koffi L.; Koné, Aboubacar; Cornélie, Sylvie; Zoh, Dounin D.; Assouho, Konan F.; Moiroux, Nicolas; Adja, Akré Maurice; Fournet, Florence

doi:10.1186/s12936-023-04457-x

Cited by 3 publications

(1 citation statement)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ecological environment and Anopheles density variability between neighborhoods could be considerable factors that explain this variation. Bouaké is characterized by the presence of lowlands used for agricultural activities, depending on the neighborhood (44). This agricultural activity has been shown to have a significant impact on vector diversity and density (30) and consequently on malaria transmission (28,29), which is highly heterogeneous across neighborhoods.…”

Section: Discussionmentioning

confidence: 99%

High prevalence of asymptomatic and sub-patentPlasmodium falciparuminfections in Urban Bouaké, Côte d’Ivoire, but nohrp2deletions: Implications for Malaria Control

Sagna,

Gebre,

Vera-Arias

et al. 2023

Preprint

View full text Add to dashboard Cite

AsymptomaticPlasmodium falciparuminfections are common in endemic settings, yet diagnosing these infections remains challenging because they are often below the limit of detection of conventional light microscopy (LM) or rapid diagnostic tests (RDTs). Deletions of thehrp2/3gene, encoding the protein detected by the most sensitive class of RDTs, present a further threat. In this study, the prevalence of asymptomatic and sub-patentP. falciparuminfections was characterized in the rainy season in the city of Bouaké, Central Côte d’Ivoire. A cross-sectional survey was conducted in nine neighborhoods of Bouaké, Côte d’Ivoire, in 2016. Matched LM, RDTs, andvarATS qPCR, were used to determine the prevalence ofP. falciparuminfections and to compare the performance of the different diagnostic methods.P. falciparum hrp2/3deletions were typed by digital PCR. Among 2313 individuals, malaria prevalence was 10.8% by microscopy, 13.0% by RDT, 35.1% by qPCR, and 37.3% (863/2313) when all three methods were combined. 96.4% (832/863) of individuals withP. falciparuminfections did not report a recent fever. 57.1% (493/863) of infections were sub-patent. The prevalence was highly heterogeneous across the neighborhoods, ranging from 15% to 55.2%, and differed among age groups (<5 years: 17.7%, 5-14 years: 42.7%, ≥15 years: 35.9%). Compared tovarATS qPCR, LM and RDT had a low sensitivity of 24.3% and 34.2%, respectively, although both methods were highly specific (>96%). Sub-microscopic malaria infections were more prevalent in ≥15-year-olds (69.9%, 349/499) and in the neighborhood of Dar es Salam (75.9%, 44/58). No hrp2 deletions were observed, and two samples carriedhrp3deletion/wild-type mixed infections. The high prevalence of asymptomatic and sub-patent infections prompts the implementation of strategies targeting these parasite reservoirs to achieve reductions in malaria burden in this high-transmission city of Côte d’Ivoire.

show abstract

Section: Discussionmentioning

confidence: 99%

High prevalence of asymptomatic and sub-patentPlasmodium falciparuminfections in Urban Bouaké, Côte d’Ivoire, but nohrp2deletions: Implications for Malaria Control

Sagna,

Gebre,

Vera-Arias

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

High prevalence of asymptomatic and subpatent Plasmodium falciparum infections but no histidine-rich protein 2 gene deletion in Bouaké, Côte d’Ivoire

Sagna,

Gebre,

Vera-Arias

et al. 2024

Sci Rep

View full text Add to dashboard Cite

This study aimed to estimate the prevalence of asymptomatic and subpatent P. falciparum infections in the city of Bouaké, Central Côte d’Ivoire, to compare the performance of three tests, and to investigate potential P. falciparum histidine-rich protein 2 ( pfhrp2 ) gene deletions. A cross-sectional survey was conducted in nine neighborhoods in Bouaké in 2016. Matched light microscopy (LM), rapid diagnostic test (RDT), and quantitative PCR (qPCR) data were used to determine the prevalence of P. falciparum infection and compare the performance of the three diagnostic tests. Pfhrp2 / 3 deletions were genotyped by digital PCR. Among 2313 individuals, 97.2% were asymptomatic and 2.8% were symptomatic. P. falciparum prevalence among symptomatic individuals was 25.8%, 30.3%, and 40.9% by LM, RDT, and var ATS qPCR, respectively, and among asymptomatic individuals, it was 10.3%, 12.5%, and 34.9%. Asymptomatic infections comprised 96.4% of all malaria infections, with 58.2% detectable only by var ATS qPCR. Although the prevalence of asymptomatic P. falciparum infections was higher in school-age children (5–14 years: 42.0%) compared to < 5 years (17.3%) and ≥ 15 years (35.9%), subpatent infections were more likely in ≥ 15 years (70.4%) than in < 5 years (39.7%) and school-age children (41.2%). LM and RDTs were reliable only at parasite densities > 10,000 parasites/µL. Individuals who were positive according to all three tests had significantly greater parasite density (856.8 parasites/µL; 95% CI 707.3–1,038) than did those who were positive by var ATS qPCR only (13.7 parasites/µL; 95% CI 11.4–16.3) (p < 0.0001). No pfhrp2 deletions were observed. The high prevalence of asymptomatic and subpatent infections highlights the need for targeted strategies to reduce malaria in urban Côte d’Ivoire.

show abstract

Insecticide resistance in Malaria vectors: Implications for control strategies in northern health districts of Cote d’Ivoire

BÉKÉ,

Edi,

Gbalegba

et al. 2024

Preprint

View full text Add to dashboard Cite

Background: Long-lasting insecticidal nets (LLINs) are the primary method used by the National Malaria Control Program (NMCP) to combat malaria. However, malaria vector resistance poses a serious threat to the success of vector control measures. The objective of this study was to analyze the current state of malaria vector resistance to commonly used insecticides in northern sentinel sites of Cote d’Ivoire. Methods: Anopheles larvae were sampled in Bouna, Korhogo, and Odienné. Adult females aged 2-5 days were subjected to various susceptibility tests according to the protocol recommended by the World Health Organization (WHO). Metabolic resistance was demonstrated by pre-exposure of mosquitoes to Piperonyl butoxide (PBO). Other insecticides such as Chlorfenapyr and Clothianidin were tested in anticipation of Indoor Residual Spraying (IRS) as a complementary vector control method in these areas. Anopheles gambiae s.l. complex subspecies were identified by polymerase chain reaction (PCR). Results: Resistance to pyrethroids, the fundamental chemical for treating LLINs, was strongly confirmed in the sentinel sites. Synergist tests demonstrated an increase in the mortality rate and restored susceptibility of malaria vectors after pre-exposure to Piperonyl butoxide (PBO). Identification of resistance mechanisms showed the presence of kdr-West and Ace-1 genes. Among these genes, kdr-West was found to be the most prevalent in the Anopheles gambiae population of Bouna (96%), Korhogo (98%), and Odienne (100%). Mosquitoes exhibited sensitivity to chlorfenapyr at a dose of 100 µg/bottle and 200 µg/bottle. However, mosquitoes showed resistance to clothianidin in each site, except for Odienné, where vectors were susceptible to this insecticide. Conclusions: The resistance of malaria vectors to commonly used insecticides is strongly confirmed in the savanna zone of northern Côte d'Ivoire. Resistance markers in this region are heterogeneous and the intensity of resistance could vary according to the ecological context of the sites. Chlorfenapyr emerges as a promising option for IRS programs, given its efficacy and absence of resistance observed in this study. Surveillance of insecticide resistance need to be continued to guide the selection of appropriate control measures.

show abstract

Entomological drivers of uneven malaria transmission in urban lowland areas in Bouaké, Côte d’Ivoire

Cited by 3 publications

References 42 publications

High prevalence of asymptomatic and sub-patentPlasmodium falciparuminfections in Urban Bouaké, Côte d’Ivoire, but nohrp2deletions: Implications for Malaria Control

High prevalence of asymptomatic and sub-patentPlasmodium falciparuminfections in Urban Bouaké, Côte d’Ivoire, but nohrp2deletions: Implications for Malaria Control

High prevalence of asymptomatic and subpatent Plasmodium falciparum infections but no histidine-rich protein 2 gene deletion in Bouaké, Côte d’Ivoire

Insecticide resistance in Malaria vectors: Implications for control strategies in northern health districts of Cote d’Ivoire

Contact Info

Product

Resources

About