Christel Host

George Washington University, Washington, Washington, D.C., United States

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Publications (2)3.47 Total impact

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    ABSTRACT: Diarrhea is the second leading cause of mortality in children under-5 worldwide. Many of these deaths can be prevented by oral rehydration therapy (ORT), improved water/sanitation, and rotavirus vaccine. In Mexico, diarrhea deaths in children under-5 have decreased dramatically over the past 3 decades as the country transitioned from lower to upper middle class economy. We set out to map the mortality reduction achieved with various public health interventions, using Mexico vital statistics, 1979-2009. Diarrheal mortality rates decreased 40-fold over the 3 decades. A distinct seasonal pattern of dramatic summer seasonality occurred in the first decade (consistent with bacterial diarrhea), but by early 1990s these summer peaks disappeared, revealing modest winter peaks consistent with rotavirus seasonality. The annual diarrheal mortality reduction temporally associated with ORT introduction in 1984, water/sanitation improvements during 1989-1999, and rotavirus vaccine introduced in 2007 was 58.8/100,000, 30.5/100,000, and 6/100,000, respectively. The rotavirus vaccine introduction in 2007, while halving the residual winter diarrhea mortality, contributed only modestly to the absolute gains in diarrheal reduction. Had the vaccine been introduced around 1980 we compute it could maximally have reduced ~18% of the large diarrhea burden at the time. We conclude that developing and lower middle class countries considering introducing the rotavirus vaccine should weigh the costs of the program against costs of introducing more universal diarrhea reduction strategies that address both summer and winter diarrhea.
    140st APHA Annual Meeting and Exposition 2012; 10/2012
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    ABSTRACT: In resource-limited settings (RLS) dried blood spots (DBS) are collected on infants and transported through provincial laboratories to a central facility where HIV-1 DNA PCR testing is performed using specialized equipment. Implementing a simpler approach not requiring such equipment or skilled personnel could allow the more numerous provincial laboratories to offer testing, improving turn-around-time to identify and treat infected infants sooner. Assess performances of a manual DNA extraction method and helicase-dependent amplification (HDA) assay for detecting HIV-1 DNA from DBS. 60 HIV-1 infected adults were enrolled, blood samples taken and DBS made. DBS extracts were assessed for DNA concentration and beta globin amplification using PCR and melt-curve analysis. These same extracts were then tested for HIV-1 DNA using HDA and compared to results generated by PCR and pyrosequencing. Finally, HDA limit of detection (LOD) studies were performed using DBS extracts prepared with known numbers of 8E5 cells. The manual extraction protocol consistently yielded high concentrations of amplifiable DNA from DBS. LOD assessment demonstrated HDA detected ∼470 copies/ml of HIV-1 DNA extracts in 4/4 replicates. No statistical difference was found using the McNemar's test when comparing HDA to PCR for detecting HIV-1 DNA from DBS. Using just a magnet, heat block and pipettes, the manual extraction protocol and HDA assay detected HIV-1 DNA from DBS at levels that would be useful for early infant diagnosis. Next steps will include assessing HDA for non-B HIV-1 subtypes recognition and comparison to Roche HIV-1 DNA v1.5 PCR assay.
    Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 01/2012; 54(1):11-4. DOI:10.1016/j.jcv.2012.01.004 · 3.47 Impact Factor