The more abundant of the two haplotypes

in the non-repeat regions of P. falciparum csp was associated with identical NANP repeats at the amino acid level in all 85 sequences from the South that showed this haplotype. The only difference among the repeat regions seen in these 85 sequences was a single synonymous point mutation seen in just one sequence. In the South of Thailand (Yala and Narathiwat Provinces), where there has been an approximately two decade-long reduction in the number of reported cases of both P. falciparum and P. vivax as a result of a concerted anti-malaria campaign, our results showed that there is also reduced nucleotide sequence BMS 354825 diversity at antigen-encoding loci. Haplotype diversities in non-repeat regions were dramatically lower in the South than in the NW of Thailand (Tak Province), significantly lower than expected if the former represented

a random sample of the latter. In the South, all antigen-encoding loci showed only a small number of haplotypes in non-repeat regions. Most strikingly, at msp2 of P. falciparum, only a single haplotype was found in 83 sequences sampled from the South, whereas there were 40 haplotypes in 195 sequences selleck chemicals llc sampled from the same locus in the NW. Several lines of evidence suggest that reduced sequence diversity in the South compared to the NW is due to population bottlenecks in the parasites caused by control measures. Fossariinae First, epidemiological data showed a decline in numbers of cases of both P. falciparum and P. vivax that began a decade earlier and thus has persisted longer in the South than in the NW. Second, the numbers of cases per year for P. falciparum and P. vivax were highly correlated in the South, suggesting that populations of both parasites were responding to the same environmental factors. Moreover, epidemiological studies have previously

noted the relatively slow progress of anti-malaria measures in the NW, which have been attributed largely to population movement across border with Myanmar, exacerbated by unstable political situations [21] and [32]. Since insecticides have played a major role in the malaria control measures in Thailand [21], a population bottleneck in their vectors has likely been the major factor in causing population bottlenecks in P. falciparum and P. vivax. Our evidence that genetic diversity in the NW has not been reduced is consistent with the epidemiological data and thus supports the conclusion that parasite genetic diversity can be impacted by control measures. Data on the numbers of malaria cases showed evidence that the anti-malaria campaign had begun to have a major impact in the NW after about 2004, representing about a decade and a half time lag relative to the South. Thus, the South had experienced a bottleneck for over a decade longer than the NW.