Acute lower respiratory infections: a major cause of death in children in Bangladesh

The importance of acute lower respiratory infections (ALRI) as a cause of death in children was estimated using systematically collected demographic data on the population of the Teknaf area of southern Bangladesh. Of 1349 children aged 1-59 months who died between 1 January 1982 and 31 December 1985, ALRI was diagnosed by verbal autopsy in 390 (29%) and was the leading cause of death. ALRI mortality rates were highest in the youngest age groups (136/1000 for those less than or equal to 5 months) and decreased in older children (16/1000 for those 3-4 years old). Half of all fatal ALRI cases occurred in children less than 6 months old. In older children, ALRI-associated deaths tended to occur during the months October to January, while deaths in infants tended to follow the seasonal birth pattern. Significant predisposing factors for fatal ALRI were malnutrition and measles, detected, respectively, in 18% and 8% of children who died from ALRI. This study emphasizes the importance of ALRI as a major cause of death in developing countries and suggests that interventions to reduce childhood mortality are needed and should be targeted to specific age groups at risk.

Serologic diagnosis of Chlamydia trachomatis infections

The serology of various infections often caused by Chlamydia trachomatis including complications such as pelvic inflammatory disease (PID) and infertility was investigated comprehensively among diverse patient groups in a developing country using initially an indirect immunofluorescent antibody test (IFA). Any positives detected were further examined by a micro-immunofluorescence (MIF) method for the presence of type specific anti-chlamydial IgG/IgM antibodies. Conventional cell culture was carried out concurrently to compare culture results with serologic results. Among 416 patients (107 males and 309 females) C. trachomatis D-K antibodies to IgG were identified in 87 (20.9%) and to type specific IgM were identified in 11(2.6%) patients. Cell culture identified C. trachomatis in 60 patients (14.4%). C. trachomatis IgG antibodies were detectable in 6.4% of chlamydia culture negative patients.

Comparison of haemagglutination test, enzyme-linked immunosorbent assay and indirect immunofluorescence antibody test for determination of rubella immune status

Comparative evaluations of immune status for rubella are described for the enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence (IFA) and two standard haemagglutination inhibition tests (HAI kaolin; HAI heparin-MnCl2). In general, a reasonably good correlation was obtained between the level of rubella antibodies measured by the HAI (kaolin) test and by ELISA, but an appreciable proportion (15%) of ELISA positive specimens were encountered among HAI (kaolin) negative sera. All of these HAI negative, ELISA positive sera, except one were found to be positive for rubella antibodies by IFA. Neutralization test performed on this serum positive by ELISA only, confirmed the presence of protective rubella antibodies. Of all the tests evaluated ELISA appeared unequivocally to be the most sensitive test followed closely by IFA. The standard HAI (heparin-MnCl2) was more suitable than the HAI (kaolin), for the determination of immune status. Further, no linear relationship between single rubella virus HAI and ELISA values was observed.

Tonsillitis and respiratory infections of viral aetiology in a developing country

Among 75 clinically diagnosed cases of tonsillitis, 55 (73.3%) were found to be of viral aetiology. Serological and virological investigations identified adenovirus as the main causative agent in children as well as in adults. In only two instances, both in children, was an association with respiratory syncytial virus (RSV) in tonsillitis detected, an extremely rare finding. A cross-sectional sero-epidemiological study of respiratory infections caused by adenovirus, RSV, influenza (A,B) and para-influenza (types 1,2,3) viruses was carried out in 289 Saudi children (newborn to 15 years of age) and 86 adults (healthy male blood donors and pregnant women) using a single serological technique. In children as well as in adults, adenoviruses were the most predominant respiratory pathogens, with no marked variation in age-specific antibody prevalence rates.

Studies on the factors affecting the haemolysin production of Vibrio mimicus isolated from clinical and environmental sources

The in vitro production of haemolysin by Vibrio mimicus, a newly described aetiological agent for human diarrhoea, was determined using sheep erythrocytes. The effects of medium composition and sodium chloride concentration on haemolysin production and its heat stability were investigated. The haemolysin was produced optimally in brain-heart infusion broth and was unaffected by salt concentration up to 1.5%. However, haemolysin production decreased gradually with increasing concentrations of salt above 1.5%, with no production at 5% NaCl. Haemolytic activity was completely lost when culture supernatants were heated at 56 degrees C for 30 min. In general, clinical strains were more haemolytic than environmental strains. The assay system described is simple and rapid, and can be used to study the pathogenic potential of V. mimicus and other noncholera vibrio strains.

Rapid diagnosis of Chlamydia trachomatis infections by a monoclonal antibody direct immunofluorescence test

A direct immunofluorescence test on 387 clinical specimens from diverse patient populations with varying prevalence rates was evaluated for the rapid diagnosis of chlamydial infections using fluorescein-labelled monoclonal antibodies for Chlamydia trachomatis. Comparative testing with the conventional cell culture indicated an overall agreement of 98.5% between the two tests and a sensitivity of 92.6%, specificity of 98.4% for the direct IF test. In high prevalence settings the direct IF could undoubtedly be used as a suitable alternative for the definitive, rapid diagnosis of chlamydial infections. In low prevalence patient populations involving primarily asymptomatic patients, sensitivity of 87.5% and specificity of 97.4% being found indicate the potential usefulness of this rapid performed test but with caution in such settings.

Rapid diagnosis of cholera by coagglutination test using 4-h fecal enrichment cultures

A simple, rapid, and reliable method to detect Vibrio cholerae in fecal specimens would assist in the management of cases of severe diarrhea, especially since most such cases occur in areas with minimal laboratory facilities. A coagglutination test was used to detect V. cholerae antigen in bile-peptone broth incubated with feces. In the technique, Staphylococcus aureus Cowan 1 coated with anti-V. cholerae O1 antiserum was tested with cultures incubated for 4 h. When 165 specimens were tested, the sensitivity, specificity, and accuracy of the test, compared with standard culture methods, were 97, 99, and 98%, respectively. These promising results were better than those of dark-field microscopy using the same specimens, and the test was logistically easy to perform. The coagglutination test using enrichment broth culture of feces is a simple and rapid method which may be used to confirm a diagnosis of cholera.

Tests for streptolysin-O antibodies in health and suspected streptococcal infections in Saudi Arabia

'Upper limits of normal' antistreptolysin-O (ASO) titres were determined in various age groups in Saudi Arabia using the conventional haemolysin and the newer, passive agglutination (Blue-ASO) tests. The upper limit of normal values were found to vary with age, being the highest (166 Todd units or 1:320) among the school age children. Serum samples from 744 patients with various clinical manifestations associated with streptococcal infections such as rheumatic fever, glomerulonephritis, tonsillitis, rheumatoid arthritis and polyarthritis were tested by both methods, with the geometric mean titres (GMT) being determined in each age group. In case of school age children with suspected rheumatic fever, and found positive by the tests, a GMT of 458 Todd units (1:1080) was obtained--much higher than the ASO levels detected in positives with glomerulonephritis or tonsillitis. Apart from its relative simplicity, rapidity and ease of performance, the Blue-ASO test was able to detect positivity in 15% of sera from patients of various age groups with suspected rheumatic fever, polyarthritis and tonsillitis who exhibited insignificant levels of ASO by the haemolysin test.

Routine screening of gynaecological and obstetric patients for Chlamydia trachomatis

Chlamydia trachomatis infection of the cervix uteri was diagnosed in 9% of 221 gynaecological and obstetric patients. Infection occurred more commonly among obstetric (12.6%) than gynaecological patients (5.5%). In obstetric patients chlamydial infection was commoner in those complaining of excessive vaginal discharge or spontaneous premature rupture of the membranes. Chlamydial infection in gynaecological patients occurred in those with previous pelvic infection, menstrual disorders or excessive vaginal discharge. No cases of chlamydial infection were detected among intrauterine device users. The enzyme immunoassay we used is an easy and relatively quick method of diagnosis for genital chlamydial infection.

Serological tests for syphilis in Saudi Arabia

A total of 6684 sera were initially screened for syphilis by the Venereal Disease Research Laboratory (VDRL) test and the Treponema pallidum haemagglutination assay (TPHA). Reactive sera from either or both these tests were tested for confirmation by the fluorescent treponemal antibody-absorbed (FTA-ABS) test. VDRL biological false positive reactors were detected in 0.5% of the total sera examined, with 0.4% and 0.8%, respectively, obtained in pregnant women and blood donors. Eight sera (0.1%) were found to be positive in the TPHA test alone. An overall positivity of 2.7% for syphilis was detected, with a 0.85% positivity in antenatal patients. Infection with T pallidum seemed to be more common in men than in women (1.6:1) and predominated in the age group 20-39 years. Serological testing of sera from 26 mother and infant pairs allowed one case of congenital syphilis to be detected by FTA-ABS (IgM) and identified VDRL biological false positivity in seven infants.

A serological survey of the prevalence of Toxoplasma gondii antibodies in dogs and cats in Saudi Arabia

The prevalence of Antibodies to Toxoplasma gondii in dogs and cats were determined by an indirect haemagglutination (IHA) test. 3% of the dogs' sera and 15.2% of that of the cats showed titres diagnostically significant of toxoplasmosis in humans; their possible role in transmission of toxoplasmosis to humans in Saudi Arabia is discussed.

Prevalence and subtype of hepatitis B surface antigen (HBsAg) in the Saudi population

Prevalence of HBsAg was studied in 5467 Saudi Arabians (2588 males, 2879 females) of various age groups from the Riyadh area, Central Province. Prevalence was found to be almost the same (6.3%-6.7%) in children less than 3 years of age in both sexes and reached its peak in the 10-14 years old for males (7.8%) and in the 3-9 years old for females (5.3%). The overall prevalence rate in males (5.2%) was significantly higher than that in Saudi females (3.7%); p less than 0.025. The predominant subtype in the Saudi population is ay (91%). Prevalence of HBsAg in 2140 Saudi blood donors was compared with that in 580 Filipino, 677 West European and 286 Yemeni blood donors. Prevalence was highest among Filippino males (12.1%) and lowest among West Europeans (0.4%). Prevalence among male Saudi blood donors was close to that among Yemeni blood donors (4.9%). In all three groups prevalence of HBsAg was higher in males than in females.

Treatment of a fatal transplantable erythroleukemia by procedures that lower endogenous erythropoietin

The in vitro growth of primary erythroleukemia cells has been examined in the presence and absence of the hormone erythropoietin (EPO). Although these leukemic cells had previously been considered to be hormone-independent, addition of EPO was found to be essential for maximum growth in culture. Erythroid colonies that grew in the presence of EPO were leukemogenic when returned to mice. Influence of EPO on the in vivo growth of leukemic cells was indicated by our findings that administration of the hormone caused a more severe leukemia and rapid death, and transfusion of red blood cells, which lowers endogenous EPO, led to decreased spleen size and increased survival of leukemic mice. We suggest from our results that hormone-associated therapy might be efficacious in the treatment of this and, perhaps, other leukemias.

Serological diagnosis of Mycoplasma pneumoniae infections

A total of 193 serum samples from patients with clinical presentations suggestive of mycoplasma pneumoniae infections were investigated by complement fixation test (CFT) and indirect haemagglutination test (IHA); these included 40 (paired) sera of 20 acute and convalescing patients. A possible correlation between the clinical findings and serologic detection of antibody to M. pneumoniae in comparison to a healthy group of the same age was studied. Comparative testing showed that a rise in antibody titre to M. pneumoniae was detected earlier by the IHA test and the clinical findings correlated reasonably well with an increased antibody titre. The IHA test in view of ts simplicity, rapidity as well as easy of performance and relative sensitivity in the early detection of antibody to M. pneumoniae is a useful adjunct to the well established CF test for the routine serodiagnosis of M. pneumoniae infections.

Serodiagnosis of human hydatid disease in Riyadh, Saudi Arabia

The Indirect Haemagglutination (IHA) test was used routinely for the diagnosis of hydatid disease in patients at the King Abdul Aziz and King Khalid University Hospitals, Riyadh, Saudi Arabia. Among 52 patients with suspected human hydatid disease, 30 positive cases were detected by means of serodiagnosis. As a control group, the level of hydatid IHA antibodies were determined in blood donors and in patients with no history of human hydatid disease. The serological results obtained in this control group showed that 70% had no hydatid IHA antibodies whereas 25% had antibody titres of 1:4 to 1:8, which are of no clinical significance.

Ear, nose and throat diseases in Saudi Arabia. Microbiology and clinical observations

Clinical specimens from 243 patients attending the ENT clinics at King Abdul Aziz University Hospital, Riyadh, Saudi Arabia were investigated for the pathogens attributing to otitis media and tonsillitis. In children as well as in adults with otitis media, the main bacterial causative organisms were Staph, aureus and Ps. aeruginosa; Asp. flavus was detected in 1% and 4% of adult and children cases of otitis media. In tonsillitis H. influenzae, Strept. pneumoniae, Staph. aureus, Strept. gr. A were isolated in only 18% of the children and Strept. pneumoniae, Strept. gr A in 16% of adults. A possible involvement of viruses in tonsillitis is indicated.

Vertical transmission of hepatitis B surface antigen in Saudi Arabia

The prevalence of hepatitis B surface antigen (HBsAg) was studied in 3020 pregnant Saudi women. All the sera of 119 (3.9%) HBsAg-positive asymptomatic carrier mothers were titrated for HBsAg and investigated for hepatitis Be antigen (e-Ag) and its antibody (anti-e-Ag). Only 13 (10.9%) of the carrier mothers were e-Ag-positive compared with 89 (74.8%) who had anti-e-Ag. There was a positive correlation between the titres of HBsAg and the presence of e-Ag. Studies on 49 mother-child pairs revealed that vertical transmission occurred from six of seven carrier mothers (85.7%) who were e-Ag positive compared with two of 32 mothers (6.25%) who were e-Ag negative but had anti-e-Ag. On the basis of these results, the low prevalence of e-Ag in asymptomatic Saudi mothers contrasts markedly with the situation in asymptomatic carrier mothers from the Orient, but its presence, as shown by other studies, is a good predictor of vertical transmission.