A total of 1429 Saudi children of either sex and under 5 years of age who were admitted to King Khalid University Hospital, Riyadh during a three year period (April 1993-March 1996) with complaints suggestive of acute respiratory tract infections (ARTI) were investigated for viral aetiology of the infection. Viruses could be detected in 522 (37 per cent) cases with respiratory syncytial virus (RSV) the most commonly detected (79 per cent) followed by parainfluenza type 3 (8 per cent). Detection of influenza A, B and adenoviruses accounted for 6 per cent, 3 per cent and 2 per cent respectively. Except for parainfluenza virus type 3 the peak of activity of the respiratory viruses was during the winter months (October-February). Parainfluenza virus type 3 could be detected all year round but epidemics can occur in the hottest months of the year (June-August) when the temperature can exceed 40 degrees C. Association between clinical manifestation, type of causative agent, and age was evaluated in 137 infected Saudi children in the first year of the study (April 1993-March 1994). The majority of our cases presented with bronchiolitis (58 per cent) while only 26 per cent had bronchopneumonia. There was a significant association between bronchiolitis and lower age groups (0-6 months), with RSV as the major causative agent of bronchiolitis cases (88 per cent).

The recombinant-based enzyme immunoassay developed by Ortho Diagnostic System for the detection of antibodies of hepatis C virus (HCV) was used to determine the extent of exposure to HCV in healthy Saudi subjects (500 males; 260 females) without liver disease and with no history of percutaneous exposure to blood and in Saudis who are considered at high risk for contracting the disease: hemophiliacs (28), thalassemics (78), hemodialysis patients with renal failure (65) and patients with sexually transmitted diseases (STD) (220). The results show that HCV is endemic in the Saudi population with an overall frequency of 5.3% in healthy Saudi adults which is at least 5 times higher than what has been reported from Western Europe and the United States. Seropositivity rate in the high-risk groups ranges from 15.9% in patients with STD to 78.6% in hemophiliacs. These data underscore the urgent need for routine anti-HCV screening of blood donations in order to reduce the frequency of postransfusion non-A, non-B hepatitis and its sequelae in the Saudi population.

SUMMARY The radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques were found to be comparable in sensitivity and specificity for detecting cytomegalovirus IgG antibody, and 10 to 100 times more sensitive than complement-fixation (CF), anticomplement immunofluorescence (ACIF) and passive haemagglutination (PHA). In screening tests for antibody, the frequency of false-positive and -negative results was 0 6% for RIA and ELISA, 1-5% for CF, 1 6% for ACIF and 3 6% for PHA. PHA was the least satisfactory test, largely because of technical problems.Cytomegalovirus (CMV) infection is an important cause of congenital brain damage' and is also a major complication of both prolonged immunosuppressive therapy, especially in patients with organ transplants,2 and multi-donor blood transfusions.3 For serological diagnosis of infection, as well as for screening for antibody in patients and in blood donors, the solid-phase indirect radioimmunoassay (RIA)" and enzyme-linked immunosorbent assay (ELISA)7-9 techniques offer distinct improvements in sensitivity over previous methods. Although the principle of both tests, based on the detection of antigen-antibody reactions by means of a labelled anti-antibody, is the same, each possesses its own particular technical advantages and disadvantages, and both require their own expensive equipment for the reading of the results. There is still a lack of data on how they compare in sensitivity and specificity. The present study was undertaken to compare the two methods for the detection of CMV IgG and to evaluate them against the older techniques of complement-fixation (CF), passive haemagglutination (PHA) and anticomplement immunofluorescence (ACIF).Material and methods virus-specific binding index (SBI) of >2 was taken to indicate the presence of virus-specific antibody and S E R A antibody titres were calculated graphically from the These were collected from women attending the ante-reciprocal of the serum dilution having an SBI of 2-0.

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The sensitivity and specificity of direct antibody radioimmunoassay (RIA), M-antibody capture RIA (MACRIA), enzyme-linked immunosorbent assay (ELISA), and the immunofluorescent antibody (IFA) test for the detection of CMV-specific IgM was compared using 40 sera selected from different groups of patients. RIA, MACRIA, and ELISA gave concordant results with thirty-two sera but discordant results with eight sera, of which three were cord sera from congenitally infected babies, three were from immunocompromised patients with recurrent CMV infections, and two were from patients with lymphadenopathy and Paul-Bunnell-positive mononucleosis, respectively. RIA, MACRIA, and ELISA were of similar sensitivity with sera from adult patients, but ELISA was apparently less sensitive than RIA and MACRIA for the detection of CMV IgM in cord serum. By comparison IFA was significantly less sensitive than the other three tests. Rheumatoid factor is reactive in RIA, ELISA, and IFA but can efficiently be removed by absorption with latex-IgG beads or cross-linked human IgG.