title: Impact of helminth diagnostic test performance on estimation of risk factors and outcomes in HIV-positive adults.
abstract: BACKGROUND
  Traditional methods using microscopy for the detection of helminth infections have limited sensitivity. Polymerase chain reaction (PCR) assays enhance detection of helminths, particularly low burden infections. However, differences in test performance may modify the ability to detect associations between helminth infection, risk factors, and sequelae. We compared these associations using microscopy and PCR.
  
  
  METHODS
  This cross-sectional study was nested within a randomized clinical trial conducted at 3 sites in Kenya. We performed microscopy and real-time multiplex PCR for the stool detection and quantification of Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, and Schistosoma species. We utilized regression to evaluate associations between potential risk factors or outcomes and infection as detected by either method.
  
  
  RESULTS
  Of 153 HIV-positive adults surveyed, 55(36.0%) and 20(13.1%) were positive for one or more helminth species by PCR and microscopy, respectively (p<0.001). PCR-detected infections were associated with farming (Prevalence Ratio 1.57, 95% CI: 1.02, 2.40), communal water source (PR 3.80, 95% CI: 1.01, 14.27), and no primary education (PR 1.54, 95% CI: 1.14, 2.33), whereas microscopy-detected infections were not associated with any risk factors under investigation. Microscopy-detected infections were associated with significantly lower hematocrit and hemoglobin (means of -3.56% and -0.77 g/dl) and a 48% higher risk of anemia (PR 1.48, 95% CI: 1.17, 1.88) compared to uninfected. Such associations were absent for PCR-detected infections unless infection intensity was considered, Infections diagnosed with either method were associated with increased risk of eosinophilia (PCR PR 2.42, 95% CI: 1.02, 5.76; microscopy PR 2.92, 95% CI: 1.29, 6.60).
  
  
  CONCLUSIONS
  Newer diagnostic methods, including PCR, improve the detection of helminth infections. This heightened sensitivity may improve the identification of risk factors for infection while reducing ability to discriminate infections associated with adverse clinical outcomes. Quantitative assays can be used to differentiate infection loads and discriminate infections associated with sequelae.
authors: Department of Epidemiology, University of Washington, Seattle, Washington, United States of America.
authors: Michael B
authors: MB
authors: Arndt
authors: Grace
authors: G
authors: John-Stewart
authors: Barbra A
authors: BA
authors: Richardson
authors: Benson
authors: B
authors: Singa
authors: Lisette
authors: L
authors: van Lieshout
authors: Jaco J
authors: JJ
authors: Verweij
authors: Laura R
authors: LR
authors: Sangaré
authors: Loice W
authors: LW
authors: Mbogo
authors: Jacqueline M
authors: JM
authors: Naulikha
authors: Judd L
authors: JL
authors: Walson
mesh_terms: D000328:Adult; D000818:Animals; D003430:Cross-Sectional Studies; D018509:DNA, Helminth / Q000235:genetics / Q000302:isolation & purification; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006679:HIV Seropositivity / Q000150:complications* / Q000276:immunology / Q000469:parasitology*; D006373:Helminthiasis / Q000150:complications* / Q000175:diagnosis* / Q000276:immunology; D006376:Helminths / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D013045:Species Specificity; D016896:Treatment Outcome
chemical_list: D018509:DNA, Helminth