Productivity of natural and artificial containers for Aedes polynesiensis and Aedes aegypti in four American Samoan villages.

Six mosquito species were identified in a survey of containers associated with 347 households in four villages in American Samoa. Aedes polynesiensis Marks (Diptera: Culicidae) and Aedes aegypti (L) were the most abundant species, representing 57% and 29% of the mosquitoes identified. Culex quinquefasciatus (Say), Culex annulirostris (Skuse), Aedes oceanicus (Belkin) and Toxorhynchites amboinensis (Doleschall) were also found. Aedes aegypti and Ae. polynesiensis showed distinct differences in their use of containers, preferring large and small containers, respectively. By contrast with previous studies, Ae. polynesiensis utilized domestic and natural containers with equal frequency, whereas Ae. aegypti continued to be found predominantly in domestic containers. Only 15% of containers holding immature mosquitoes included pupae and fewer than 10 Aedes spp. pupae were found in most containers with pupae. An estimated 2289 Ae. polynesiensis and 1640 Ae. aegypti pupae were found in 2258 containers. The presence of both species in the same container did not affect the mean density of either species for larvae or pupae. Glass jars, leaf axils, tree holes and seashells produced few Aedes spp. pupae in any of the study villages. Overall, 75% of Ae. polynesiensis pupae were found in buckets, ice-cream containers and tyres, with <7% being produced in natural containers, whereas 82% of Ae. aegypti pupae were found in 44-gallon (US) drums ( approximately 166L), buckets and tyres. Source reduction efforts targeting these container types may yield significant reductions in both Ae. polynesiensis and Ae. aegypti populations in American Samoa.

Human leptin locus (LEP) alleles and BMI in Samoans.

OBJECTIVES: Because of their location in known candidate gene regions for obesity the associations between six microsatellite markers (D2S2170, D2S144, D2S1268, D2S1788, D2S1348 and a tetranucleotide repeat in the 3' UTR of the LEP locus) and body mass index (BMI) were studied in adult Samoans. DESIGN: The study was designed to detect differences in the proportion of alleles at the six microsatellite markers between two groups of adult Samoans at the extremes of the longitudinal BMI distribution. SUBJECTS AND MEASUREMENTS: The 181 unrelated Samoan participants were 25-55 y of age, reported that all four grandparents were Samoan, resided in American Samoa (AS) or Samoa (S) and were without diagnosed hypertension or type 2 diabetes. Initial statistical analysis was based on chi(2) tests of independence between marker allele frequencies and BMI status at each marker. The association of individual alleles with BMI status was tested by aggregating a marker's allelic data into a two-by-two contingency table and applying a two-tailed version of Fisher's exact test, with a Bonferroni correction to account for the multiple testing implicit in the procedure. RESULTS: There were no significant differences in allele frequencies at any of the markers between AS and S, as expected from our prior population genetic analyses. Only the LEP gene 3'-tetranucelotide repeat was associated (P<0.006) with BMI status. The distribution of the marker alleles at the LEP locus was significantly associated with the BMI groups (P<0.01), due to the low frequency of allele 226 in the high BMI group. The same pattern of association was found in sub-group analyses with low BMI individuals from AS and high BMI individuals from S. CONCLUSION: These findings indicate that the leptin 3'-tetranucleotide repeat is associated with high BMI in adult Samoans, with allele 226 having a low frequency in the high BMI group.

Type 2 diabetes and three calpain-10 gene polymorphisms in Samoans: no evidence of association.

Although genomewide scans have identified several potential chromosomal susceptibility regions in several human populations, finding a causative gene for type 2 diabetes has remained elusive. Others have reported a novel gene, calpain-10 (CAPN10), located in a previously identified region on chromosome 2q37.3, as a putative susceptibility gene for type 2 diabetes. Three single-nucleotide polymorphisms (SNPs) (UCSNP43, UCSNP19, and UCSNP63) were shown to be involved in increased risk of the disease among Mexican Americans. We have tested the association of these three SNPs with type 2 diabetes among the Samoans of Polynesia, who have a very high prevalence of the disease. In the U.S. territory of American Samoa, prevalence is 25% and 15% in men and women, respectively, whereas, in the independent nation of Samoa, prevalence is 3% and 5% in men and women, respectively. In our study sample, which consisted of 172 unrelated affected case subjects and 96 control subjects, we failed to detect any association between case subjects and control subjects in allele frequencies, haplotype frequencies, or haplotype combinations of UCSNP43, -19, and -63. Also, our data showed no evidence of linkage, among 201 affected sib pairs, in the region of chromosome 2 that contains these SNPs. Three plausible scenarios could explain these observations. (1) CAPN10 is a susceptibility gene only in particular ethnic groups; (2) our study lacks power to detect the effects of CAPN10 polymorphisms (but our sample size is comparable to that of earlier reports); or (3) the underlying biological mechanism is too complex and requires further research.