title: Effect of seasonal variation on adult clinical laboratory parameters in Rwanda, Zambia, and Uganda: implications for HIV biomedical prevention trials.
abstract: OBJECTIVE
  To investigate the effect of seasonal variation on adult clinical laboratory parameters in Rwanda, Zambia, and Uganda and determine its implications for HIV prevention and other clinical trials.
  
  
  METHODS
  Volunteers in a cross-sectional study to establish laboratory reference intervals were asked to return for a seasonal visit after the local season had changed from dry to rainy or vice versa. Volunteers had to be clinically healthy, not pregnant and negative for HIV, Hepatitis B and C, and syphilis infection at both visits. At each visit, blood was taken for measurement of hemoglobin, haematocrit, mean corpuscular volume, red blood cells, platelets, total white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils, basophils, CD4/CD8 T cells, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, direct bilirubin, total bilirubin, total immunoglobulin gamma, total protein, creatinine, total amylase, creatine phosphokinase and lactate dehydrogenase (LDH). Consensus dry season reference intervals were applied to rainy season values (and vice versa) and the proportion of 'out-of-range' values determined. Percentage differences between dry and rainy season parameter mean values were estimated.
  
  
  RESULTS
  In this cohort of 903 volunteers, less than 10.0% of consensus parameter (except LDH) values in one season were "out-of-range" in the other. Twenty-two (22) percent of rainy season LDH values fell outside of the consensus dry season interval with the higher values observed in the rainy season. Variability between consensus seasonal means ranged from 0.0% (total WBC, neutrophils, monocytes, basophils, and direct bilirubin) to 40.0% (eosinophils). Within sites, the largest seasonal variations were observed for monocytes (Masaka, 11.5%), LDH (Lusaka, 21.7%), and basophils (Kigali, 22.2%).
  
  
  CONCLUSIONS
  Seasonality had minimal impact on adult clinical laboratory parameter values in Rwanda, Zambia, and Uganda. Seasonal variation may not be an important factor in the evaluation of adult clinical laboratory parameters in HIV prevention and other clinical trials in these countries.
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Eugene
authors.initials: E
authors.lastname: Ruzagira
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Andrew
authors.initials: A
authors.lastname: Abaasa
authors.affiliation: Projet San Francisco (PSF), Kigali, Rwanda.
authors.forename: Etienne
authors.initials: E
authors.lastname: Karita
authors.affiliation: Zambia-Emory HIV Research Project (ZEHRP), Lusaka, Zambia; Zambia Blood Transfusion Service, Lusaka, Zambia.
authors.forename: Joseph
authors.initials: J
authors.lastname: Mulenga
authors.affiliation: Zambia-Emory HIV Research Project (ZEHRP), Lusaka, Zambia.
authors.forename: William
authors.initials: W
authors.lastname: Kilembe
authors.affiliation: Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America.
authors.forename: Susan
authors.initials: S
authors.lastname: Allen
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Bahemuka
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Agnes N
authors.initials: AN
authors.lastname: Bwanika
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Levin
authors.affiliation: International AIDS Vaccine Initiative, New York, New York, United States of America; Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California, United States of America.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Price
authors.affiliation: Medical Research Council (MRC)/Uganda Virus Research Institute (UVRI) Uganda Research Unit on AIDS, Entebbe, Uganda.
authors.forename: Anatoli
authors.initials: A
authors.lastname: Kamali
mesh_terms: D000293:Adolescent; D000328:Adult; D002980:Climate; D003430:Cross-Sectional Studies; D005260:Female; D006678:HIV / Q000302:isolation & purification; D015658:HIV Infections / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D006403:Hematologic Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012432:Rwanda / Q000453:epidemiology; D012621:Seasons; D014454:Uganda / Q000453:epidemiology; D055815:Young Adult; D015024:Zambia / Q000453:epidemiology