Laboratory diagnosis of viral hepatitis C: the Sultan Qaboos University Hospital experience

A retrospective study was carried out to assess the performance of hepatitis C diagnostic assays in our laboratory, and to determine the prevalence of hepatitis C among blood donors at the Sultan Qaboos University Hospital. From 1991 to 2001, approximately 55,000 serum samples collected from blood donors and patients were submitted to our laboratory for testing. All sera were screened for antibodies to hepatitis C virus [HCV] by three successive generations of the enzyme-linked immunosorbent assay [ELISA]. Anti-HCV positive sera were further tested by recombinant immunoblot assay [RIBA]. Reverse-transcriptase polymerase chain reaction [RT-PCR] for HCV RNA was carried out on a limited number [241] of ELISA positive samples. Out of 30012 samples from blood donors that were screened for anti-HCV, 272 [0.91%] were positive. Of these, 46.5% were confirmed positive by RIBA. The proportion of patient sera that were confirmed positive varied from 95% among intravenous drug users to 81% in patients with hepatitis to 70% in those with haemoglobinopathies. HCV RNA was detected in 67%, 6%, and 0% of the RIBA positive, indeterminate and negative samples respectively. Based on RIBA, the prevalence of anti-HCV among blood donors in Oman is close to 0.5%. In our experience, RIBA-positivity is predictive of HCV infection in two thirds of subjects, and HCV infection is highly unlikely in those who are RIBA-negative. The experience at SQUH with three types of HCV assays has enabled the laboratory to develop a test algorithm, starting with screening anti-HCV ELISA

Fluctuating antibody response in a cohort of hepatitis C patients

This project was designed to longitudinally study persons who had antibodies to hepatitis C virus [HCV] to characterise the serologic course of infection. The subjects were 149 multitransfused patients [141 with thalassaemia major, 3 with thalassaemia intermedia, and 5 with sickle cell anaemia] who had been regularly followed up for 3 to 7 years. Sequential serum samples obtained semi-annually between January 1994 and January 2001 were tested, prospectively, by second or third generation HCV enzyme-linked immunosorbent assay [ELISA], followed by confirmatory recombinant immunoblot assay [RIBA-2 or RIBA-3]. Of the 149 patients, 90 did not seroconvert to HCV, whereas 59 had detectable antibodies. On the basis of RIBA results in these 59 patients, 24 [41%] had persistent high antibody levels to structural and non structural HCV antigens, 11 [19%] had persistent low antibody levels, 17 [29%] showed fluctuating antibody levels, and in 5 patients [8%] there was a total or a partial disappearance of specific antibodies [seroreversion], mainly anti-core antibodies. Two patients [3%] had antibody responses that did not fit into any of these four categories. In patients with fluctuating antibody levels, there were periods ranging from 6 months to 2 years when anti-HCV antibodies could not be detected. This study shows that the antibody response to HCV in patients who receive frequent blood transfusions is very variable. Individuals who exhibit intermittent seropositivity are a challenge to diagnosis

Prevalence of rotavirus gastroenteritis at a University Teaching Hospital in Oman: a four-year study

The study was undertaken to determine the prevalence of rotavirus infection in children with gastroenteritis, and to correlate this prevalence with demographic and climatic conditions that might influence virus transmission. Stool samples from 991 children with gastroenteritis who were seen at sultan Qaboos University Hospital between Janaury 1996 and December 1999 were tested for rotavirus antigen by a latex agglutination test. Data on patients' age and gender, and the unit within the hospital where the patient was treated, were recorded Monthly temperature and relative humidity data were obtained from reports of the Department of Meteorology of the Directorate of Civil Aviation. Rotavirus antigen was detected in 114 [11.5%] of the children with diarrhea. Ninety percent of rotavirus gastroenteritis cases were under 2 years of age but neonatal rotavirus was not encountered and the youngest patient was 3 months of age. The prevalence of rotavirus infection was significantly higher in hospitalised than non-hospitalised children [12.6% v/s 7.0%, p<0.05] Infection was also more common in males than females [12.5% v/s 10.0%] but this difference was not statistically significant [p<0.25%]. More infections occurred during the cooler months of December, January and February than in the hotter months but there was no correlation with relative humidity. Rotavirus is a significant cause of gastroenteritis in young children seen at Sultan Qaboos University Hospital. Environmental temperature has some influene on virus transmission but not relative humidity