Seroprevalence of antibodies to repetitive domains of Plasmodium vivax circumsporozoite protein in United Arab Emirates children

The aim of this study was to determine the exposure of child citizens of the United Arab Emirates (UAE) to Plasmodium vivax, and to elucidate if it was related to place of residence or previous international travel to malaria-endemic areas. Blood samples were collected from 1010 primary schoolchildren resident in 7 out of 9 districts of the UAE during October and November 1999. Plasma samples were tested for antibodies against MAP4 (DGQPAGDR)₃P2P30, a multiple antigen peptide containing the repeat amino acid sequences of P. vivax circumsporozoite protein (CSP), conjugated to 2 T-helper epitopes, P2 (QYIKANSKFIGITE) and P30 (FNNFTVSFWLRVPKVSASHLE) from tetanus toxin. For confirmation of P. vivax-specific reactivity, positive samples were further tested against (AGDR)₆, a synthetic peptide containing 6 copies of a protective epitope within the CSP, and against a recombinant CSP, designated as NS1₈₁ V20. Results indicated that 3.3% of the children were seropositive. The seropositivity rates differed significantly in relation to place of residence, whereas travel outside the UAE did not significantly affect the exposure rates to P. vivax.