Stream flow composition and sediment yield comparison between partially urbanized and undisturbed coastal watersheds-case study: St. John, US Virgin Islands.

In steep dry-tropical islands, rural and urban development can lead to accelerated soil erosion and the delivery of land-based materials into marine ecosystems. The objective of this paper was to compare stream water composition, clay minerology, and sediment yield between a partially urbanized (Coral Bay) and an undisturbed (Lameshur) coastal watersheds in St. John, US Virgin Islands (USVI). The saturation index of streamflow water samples was calculated using "The Geochemist's Workbench" software and most likely precipitated minerals from observed storm events was then compared with X-ray diffraction on soil clay mineralogy. The spatial distribution on both annual mean (2010) erosion rates and storm event-wise (Hurricane Otto) sediment yield among the two study watersheds were modeled using the revised and modified universal soil loss equations (RUSLE; MUSLE), respectively. Cations concentration in stream flow water samples and sediment yield were higher for the partially urbanized (Coral Bay) compared to the undisturbed (Lameshur) watershed. Our findings suggest that rural/urban development may increase stream water cations concentration and inputs of sediment to downstream ecosystems. Future studies evaluating the effect of management practices such as pavement or other stabilization of dirt roads and their impact on stream water quality and quantity and sediment yield are crucial for the proper sediment management in the study watersheds and potentially in other rural-urbanizing tropical watersheds.

Progress towards elimination of HIV mother-to-child transmission in the Dominican Republic from 1999 to 2011.

In 1999, prevention of mother-to-child transmission (pMTCT) using antiretrovirals was introduced in the Dominican Republic (DR). Highly active antiretroviral therapy (HAART) was introduced for immunosuppressed persons in 2004 and for pMTCT in 2008. To assess progress towards MTCT elimination, data from requisitions for HIV nucleic acid amplification tests for diagnosis of HIV infection in perinatally exposed infants born in the DR from 1999 to 2011 were analyzed. The MTCT rate was 142/1,274 (11.1%) in 1999-2008 and 12/302 (4.0%) in 2009-2011 (P < .001), with a rate of 154/1,576 (9.8%) for both periods combined. This decline was associated with significant increases in the proportions of women who received prenatal HAART (from 12.3% to 67.9%) and infants who received exclusive formula feeding (from 76.3% to 86.1%) and declines in proportions of women who received no prenatal antiretrovirals (from 31.9% to 12.2%) or received only single-dose nevirapine (from 39.5% to 19.5%). In 2007, over 95% of DR pregnant women received prenatal care, HIV testing, and professionally attended delivery. However, only 58% of women in underserved sugarcane plantation communities (2007) and 76% in HIV sentinel surveillance hospitals (2003-2005) received their HIV test results. HIV-MTCT elimination is feasible but persistent lack of access to critical pMTCT measures must be addressed.