Prevalence and detection of Trichomonas vaginalis in HIV-infected pregnant women

BACKGROUND : Trichomonas vaginalis is a sexually transmitted infection associated with increased transmission of HIV and significant adverse birth outcomes; culture and polymerase chain reaction (PCR) are commonly used in diagnosis. METHODS : Consenting HIV-infected pregnant women were recruited from clinics in South Africa and screened for T. vaginalis using PCR. Polymerase chain reaction-positive women provided an additional sample for culture. We compared T. vaginalis detection between PCR and culture, and investigated how PCR cycle threshold (Ct) values differ among culture results. RESULTS : A total of 359 women were enrolled and 76 (20%) tested T. vaginalis PCR positive. Cultures were obtained from 61 of the PCR-positive women, and 38 (62%) were culture positive. The median baseline Ct of the PCR-positive/culture-positive group was 22.6 versus 38.0 among those who were PCR positive/culture negative (P < 0.001). Culture-positive cases had lower Ct values (higher DNA load); a Ct value less than 30 predicted positivity with a sensitivity of 97% and a specificity of 96%. CONCLUSIONS : Culture was positive in roughly half of PCR-positive cases. The culture-negative cases had significantly higher Ct values, indicating a lower concentration of T. vaginalis DNA. A Ct value of 30 provides a reliable threshold for predicting culture positivity. The clinical significance of culture-negative infections detected by PCR is still unclear.The National Institutes of Health (Grant No. 1-R21-HD084274-01A1), the US President's Emergency Plan for AIDS Relief (Cooperative Agreement: AID-674-A-12-00017), and a travel grant from the UCLA Center for World Health.http://journals.lww.com/stdjournal/pages/default.aspx2019-05-01hj2018Medical MicrobiologySchool of Health Systems and Public Health (SHSPH

Equity Dilution: An Alternative Perspective on Mortgage Default

Empirical research on mortgage default in the single-family market has focused on the value of the borrower's put option using house price indices to estimate contemporaneous loan-to-value ratio or the probability of negative equity. But since the borrower possesses the option to increase leverage by taking on additional debt secured by junior liens subsequent to loan origination (a phenomenon termed here equity dilution), even a perfect house price adjustment cannot be expected to accurately measure changes in borrower equity over time. Since junior liens are generally unobservable to senior debt holders, proxies are required in empirical applications. This paper employs an independent estimate of junior lien probability developed from the 1998 Survey of Consumer Finances combined with loan level mortgage performance data to examine the role junior liens play in increasing default risk. Copyright 2004 by the American Real Estate and Urban Economics Association

The Effect of Conforming Loan Status on Mortgage Yield Spreads: A Loan Level Analysis

The magnitude of the effect of government-sponsored enterprise purchases on primary mortgage market rates has been a difficult research question with differing data and competing methodologies producing varying results. Here we present a new approach using loan level data and controlling for credit risk differentials between conforming and nonconforming loans. Our method also addresses econometric problems of endogeneity and sample selection bias. We find that conforming loans have yield spreads about 5.5% lower compared to other loans on a risk-adjusted basis. This is lower than previous estimates appearing in the literature. Copyright 2004 by the American Real Estate and Urban Economics Association