ABSTRACT
Background: In order to scale up access to HIV counselling and testing in Nigeria; an HIV diagnostic algorithm based on rapid testing was adopted. However; there was the need to further evaluate the testing strategy in order to better assess its performance; because of the potential for false positivity.Objectives: The objective of this study was to compare positive HIV test results obtained from the approved rapid testing algorithm with results from western blot tests performed on samples from the same patient.Methodology: A retrospective review was conducted of HIV screening and confirmatory results for patients seen between 2007 and 2008. Rapid test and western blot results were extracted and compared for concordance. Discordant results were further reviewed using a combination of HIV-1 RNA viral load and CD4+ cell count test results and clinical presentation from medical records. Results: Analysis of 2228 western blot results showed that 98.3% (n = 2191) were positive for HIV-1; 0.4% (n = 8) were positive for HIV-2 and 0.3% (n = 7) were dual infections (positive for both HIV-1 and HIV-2); 0.6% (n = 13) were indeterminate and 0.4% (n = 9) were negative. Further investigation of the 13 indeterminate results showed nine to be HIV-1 positive and four to be HIV-negative; for a total of 13 negative results. The positive predictive value of the HIV counselling and testing algorithm was 99.4%.Conclusion: Using the rapid testing algorithm alone; false positives were detected. Therefore; effective measures such as training and retraining of staff should be prioritised in order to minimise false-positive diagnoses and the associated potential for long-term psychological and financial impact on the patients
Subject(s)
Algorithms , HIV Infections/diagnosis , HIV SeropositivityABSTRACT
This study aimed at characterizing the phenotypic and toxigenic status of circulating strains of cholera during outbreaks in Nigeria, employing molecular typing techniques. Two hundred and one samples of rectal swabs, stool, vomitus, water (from the well, borehole, sachet, stream, and tap) and disinfectants (sodium hypochlorite) were collected from three states in the country. The samples were inoculated on thiosulphate-citrate bile salt-sucrose (TCBS), Cary-Blair transport medium and smeared on glass slides for direct examination. The Vibrio cholerae isolates were serotyped, biotyped, and characterized using PCR of the cytotoxin gene A (ctxA), wbeO1, and wbfO139 gene primer. Of the 201 samples screened, 96 were positive for V. cholerae O1 (48%), with 69 (72%) positive for ctxA gene. The results from this study showed that the circulating strains of cholera in Nigeria were of Ogawa serotype, also observed in other outbreaks in Nigeria (1991, 1992, and 1996). However, the strains were of the Classical biotype and were mainly (72%) ctxA gene-positive. This current investigation has confirmed the production of cholera toxin by the circulating strains, and this could be harnessed for possible cholera vaccine production in Nigeria.
ABSTRACT
Laboratory diagnosis of Chlamydia and vaginitis in sexually active females has been limited by unavailability of a sequential method/rapid technique for simple diagnosis. Six hundred (600) adult females from hotel/brothel; Sexually Transmitted Infections (STIs) Clinic; Obstetrics/Gynaecology Clinic; Family Planning Clinic and Healthy controls were investigated for Chlamydia; Candida; trichomoniasis and bacterial vaginosis (BV). This was done using microscopy: wet mount; stained vaginal secretion and stained smear after culture. Results showed that there were 72infections in the female groups. The brothel and STI group had infection in the range (70-86). Chlamydial infection was highest in the STI group while Candida infection was highest in the healthy (control) females. Bacterial vaginosis was distributed in all groups. As p-value increased; f-value increased indicating constant co-infection of Candida and BV in Chlamydia positive females. Microscopy by direct detection from sample and stained smear after culture were in the range: 56-86. Direct microscopy for BV was 78.5and stained smear after culture; 57.1. Sensitivity and specificity of the techniques showed that detection of Chlamydia was less sensitive by direct microscopy of sample but sensitivity and specificity of stained smear after culture were high. Immunoassay (32.2) was also less sensitive. Sensitivity and specificity of wet mount microscopy for Candida; Trichomoniasis and BV were in the range 62.5 - 80and 62.5-97.8respectively. Wet mount has high sensitivity and specificity for detecting agents of vaginitis and may be useful for routine use and for diagnosis where disease is absent; thus; making identification more cost effective