Plasmodium vivax infections in pregnant women are associated with low birth weight and anemia. Genotyping of P.vivax is useful to study P. vivax in pregnancy, though it is still remains challenging to distinguish between relapse from hypnozoite stage and recrudescence from blood stage following treatment. A genetic investigation of P.vivax in pregnancy on the Thai-Burmese border, comparing the genotype between at follow up with the day of admission for pregnant patients and non pregnant patients was undertaken in this study.
Materials and methods
One hundred and sixteen blood samples infected with P.vivax were isolated from 18 pregnant women with ≥2 episodes obtained from whole blood (12 women had 2 reappearances, 4 and 2 women had 3 and 4 reappearances, respectively) and 18 non-pregnant women with 2 consecutive episodes collected on dried blood spot. All samples were genotyped with eight microsatellite markers. Analyses were performed for genetic diversity, multiplicity of infection (MOI), and comparison of genotypes for individual episodes detected in samples.
Eight microsatellite loci, 6 to 15 alleles were found at each locus. The mean number of alleles per locus was 1.40 and 1.17 (p<0.001) for pregnant and non-pregnant patients, respectively. The overall mean expected heterogygosity (He) was 0.845 in both groups. In pregnant patients, the multiplicity of infection (MOI) was 1.85 while it was 1.44 (p=0.028) in non-pregnant patients.
The greater number of minor alleles in pregnant patients may either the nature of the sample.
Combined genetic data from days of follow and day of admission showed that genotypes were different 57 % (25/44) of those pregnant patients and 58 % (21/36) of non-pregnant patients (p=0.891).
This study confirmed that different P.vivax genotypes were found during follow up when compared to day of admission in both groups.
Supported by grant from under the program "Strategic Scholarships for Frontier Research Network for the Ph.D." Program Thai Doctoral degree from the Office of the Higher Education Commission, Thailand and the Wellcome Trust of Great Britain.