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  1. Clarisse Njua-Yafi1,
  2. Theresa Nkuo-Akenji2,
  3. Judith Anchang-Kimbi2,
  4. Tobias Apinjoh2,
  5. Regina Mugri2,
  6. Hanesh Chi2,
  7. Rolland Tata2,
  8. Charles Njumkeng2,
  9. Daniel Dodoo3,
  10. Michael Theisen4,
  11. Eric Achidi2
  1. 1University of Yaoundé I, Cameroon
  2. 2University of Buea, Cameroon
  3. 3NMIMR, Ghana
  4. 4SSI, Denmark


Background Malaria and helminthiases overlap extensively in their epidemiological distributions, and co-infections are common. Helminth infection has a profound effect on the immune system such as the induction of immuno-regulatory mechanisms such as potent regulatory T cell responses known to suppress cellular effector mechanisms.

Methods The prevalence of malaria parasitaemia, intestinal helminths, co-infection and anaemia was determined in a cross-sectional study (March 2011) of 372 children aged 6 months to 10 years resident in Mutengene in south-western Cameroon. Plasma total IgG and IgG1–4 subclass antibody levels to P. falciparum apical membrane antigen 1 (AMA1), the N-terminal non-repeat region (GLURP R0) and the C-terminal repeat region of glutamate rich protein (GLURP R2) and merozoite surface protein 3 (MSP3) were measured by standardised ELISA.

Results Prevalence was as follows: malaria parasitaemia (mp) 18%, pyrexia 25.4%, helminths 19.7%, and anaemia 71.5%. Amongst those who were mp-positive, 25.4% were symptomatic (4.5% overall). Almost all helminth infections were the soil-transmitted helminths Ascaris, Trichuris and hookworm (96.4%) with a few cases of Hymenolepis and Enterobius. Haemoglobin concentration (g/dl) correlated positively with age and negatively with mp density (p≤0.001). The mean haemoglobin (g/dl) level of participants co-infected with both parasites (3.4%) was higher compared to participants infected with either Plasmodium (15.8%) or helminths (16.1%) alone (p< 0.01). IgG and IgG1–4 subclass antibody levels to all recombinant antigens correlated positively with age (p< 0.01). Total IgG, IgG1, 2 & 3 levels to all the antigens tested were significantly (except MSP3 IgG2, p=0.08) higher in participants infected with Plasmodium alone, compared to the co-infection, helminths only and no infection groups. Decreased levels of AMA1 IgG associated significantly with co-infection (OR=0.27, 95% CI:0.11–0.68). Increased MSP3 IgG and IgG1–4 levels were significantly associated with children infected with Plasmodium alone compared to children co-infected with both parasites.

Conclusions Infection with intestinal helminths stifles protective anti-plasmodial antibody responses.

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