Tropical Medicine and Infectious Disease (Jul 2023)

High Prevalence of Polyclonal <i>Plasmodium falciparum</i> Infections and Association with Poor IgG Antibody Responses in a Hyper-Endemic Area in Cameroon

  • Marie Florence A Bite Biabi,
  • Balotin Fogang,
  • Estelle Essangui,
  • Franklin Maloba,
  • Christiane Donkeu,
  • Rodrigue Keumoe,
  • Glwadys Cheteug,
  • Nina Magoudjou,
  • Celine Slam,
  • Sylvie Kemleu,
  • Noella Efange,
  • Ronald Perraut,
  • Sandrine Eveline Nsango,
  • Carole Else Eboumbou Moukoko,
  • Jean Paul Assam Assam,
  • François-Xavier Etoa,
  • Tracey Lamb,
  • Lawrence Ayong

DOI
https://doi.org/10.3390/tropicalmed8080390
Journal volume & issue
Vol. 8, no. 8
p. 390

Abstract

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Malaria remains a major public health problem worldwide, with eradication efforts thwarted by drug and insecticide resistance and the lack of a broadly effective malaria vaccine. In continuously exposed communities, polyclonal infections are thought to reduce the risk of severe disease and promote the establishment of asymptomatic infections. We sought to investigate the relationship between the complexity of P. falciparum infection and underlying host adaptive immune responses in an area with a high prevalence of asymptomatic parasitaemia in Cameroon. A cross-sectional study of 353 individuals aged 2 to 86 years (median age = 16 years) was conducted in five villages in the Centre Region of Cameroon. Plasmodium falciparum infection was detected by multiplex nested PCR in 316 samples, of which 278 were successfully genotyped. Of these, 60.1% (167/278) were polyclonal infections, the majority (80.2%) of which were from asymptomatic carriers. Host-parasite factors associated with polyclonal infection in the study population included peripheral blood parasite density, participant age and village of residence. The number of parasite clones per infected sample increased significantly with parasite density (r = 0.3912, p p P. falciparum antigens (MSP-1p19, MSP-3 and EBA175) and two soluble antigen extracts (merozoite and mixed stage antigens). Surprisingly, we observed no association between the frequency of polyclonal infection and susceptibility to clinical disease as assessed by the recent occurrence of malarial symptoms or duration since the previous fever episode. Overall, the data indicate that in areas with the high perennial transmission of P. falciparum, parasite polyclonality is dependent on underlying host antibody responses, with the majority of polyclonal infections occurring in persons with low levels of protective anti-plasmodial antibodies.

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