Detection of poliovirus, hepatitis A virus and rotavirus from sewage and water samples.

A modified adsorption-elution technique for concentration of enteric viruses from sewage and water samples was developed. The viruses in water were concentrated by negatively charged membrane filtration, eluted with 2.9% tryptose phosphate broth containing 6% glycine pH 9.0, and reconcentrated using centrifugation by a speedVac concentrator. The presence of poliovirus, hepatitis A virus (HAV) RNA, and rotavirus antigen was determined by cell culture isolation, nested polymerase chain reaction (nested PCR), and enzyme-linked immunosorbent assay (ELISA), respectively. A total of 100 sewage and water samples were collected from various sources in congested communities in Bangkok, concentrated and examined for those enteric viruses. Of 20 surface water samples from canals which located near sewage drains, 15% were positive for HAV RNA by nested PCR. Of 48 domestic sewage samples from man-holes of underground sewers, 8% were positive for rotavirus antigen by ELISA. Even though the samples were concentrated 256-2,000 fold, poliovirus was not found by isolation in cell culture.

Prevalence of type specific Epstein-Barr virus in the genital tract of genital herpes suspected patients.

A total of 62 clinical specimens from the genital tract of patients who were suspected of contracting genital herpes were investigated for HSV infection by the virus isolation method, and also investigated for the co-infection with EBV infection by detecting EBV DNA using nested PCR. HSV infection was diagnosed in 30 (48.4%) of the study cases, and so was EBV. EBV DNA was present in 17 (56.7%) of the 30 HSV positive samples. No correlation was found between the co-existence of these two viruses together. EBV DNA was detected in genital specimens of cervical, vaginal, urethral, and anal swabs. Ninety per cent of EBV belonged to type 1, and the remainder belonged to type 2 and mixed types. The role of EBV in genital tract infection needs to be further investigated.

Comparison between virus isolation method, Papanicolaou stain, immunoperoxidase stain and polymerase chain reaction in the diagnosis of genital herpes.

Papanicolaou (Pap) stain, immunoperoxidase (IP) stain and polymerase chain reaction (PCR) were evaluated against the virus isolation method for their sensitivity and specificity in the diagnosis of herpes simplex virus (HSV) infection in 96 women who were suspected of genital herpes. The result showed that the sensitivity of PCR, IP and Pap stain was 100, 92.0 and 62.7%, respectively, while the specificity was 76.2, 66.7 and 81.0%, respectively. PCR was even more sensitive than the virus isolation technique. As Pap stain is the technique routinely performed for diagnosing genital herpes in most of the hospitals in Thailand, its low sensitivity should be taken into consideration. Based on the investigation by all four techniques together, HSV infection was diagnosed in 91.6% of the cases suspected of genital herpes which reflected higher precision of the clinical diagnosis over Pap stain.

Prevalence of herpes simplex virus infection in patients suspected of genital herpes; and virus typing by type specific fluorescent monoclonal antibodies.

During the period between April 1994 and February 1996, a total of 154 female patients who attended the Clinic of Female Sexually Transmitted Diseases, Siriraj Hospital with clinical symptoms suspected of genital herpes were investigated for herpes simplex virus (HSV) infection by the virus isolation method in Vero cell cultures. Swabs from external genital lesions and the cervix from each patient were collected separately and used as the clinical specimens for isolation of HSV. The virus isolates were identified by indirect immunofluorescence (IIF) staining of the infected cell cultures using polyclonal HSV-2 specific antiserum which was reactive to common HSV antigens for both types of viruses. Typing of HSV was performed by direct IF using monoclonal antibody specific to HSV-1 or HSV-2. HSV was isolated from 78.6 per cent (121 of 154) of the cases studied; and among the infected cases, there were 47.9 per cent (58 of 121) in whom the infection involved both external genital lesions and cervixes, and 50.4 per cent (61) in whom the infection was limited to external genital lesions only. There were 2 cases (1.7%) in whom HSV was isolated from cervixes but not external genital lesions. Seventy-five HSV isolates were further subjected to typing. The present study showed that HSV-1 was accounted for 18.7 per cent (14 isolates), while HSV-2 took the remaining part of 81.3 per cent (61 isolates). The data demonstrated an increase in the prevalence of HSV-1 in genital herpes in our people.

Acute hemorrhagic conjunctivitis outbreak in Thailand, 1992.

The 260 cases of acute hemorrhagic conjunctivitis seen at Siriraj Hospital during October to December, 1992 were studied. Evidence of coxsackie virus A24 variant (CA24v) infections was demonstrated in 76.8% of 95 cases. The isolation rates from conjunctival swabs and throat swabs were 68.2% and 32.8%, respectively. A four-fold rising titer of neutralizing antibody was shown in 59.5% of 42 cases. The disease was characterized by a short incubation period, sudden onset, a mild and self-limited course within 5 days without ocular sequelae. Lacrimation, swelling lida, itching, foreign body sensation and periorbital pain were common features with bilateral involvement in the majority of cases. Approximately 48% of eyes had a mucopurulent discharge. Preauricular lymphadenopathy, keratitis and subconjunctival hemorrhage were observed in 16.2%, 12.6%, and 10.1% of affected eyes, respectively. Respiratory disturbances accompanied the eye signs in some cases. Only one case developed neurological complications: facial palsy was observed for three months without recovery.

Incidence of Mycoplasma pneumoniae, Chlamydia trachomatis, and viral infections in pneumonia cases under six months of age, Bangkok, Thailand.

The incidence of infections by Mycoplasma pneumoniae, Chlamydia trachomatis and respiratory viruses was investigated in 76 pneumonic patients aged under 6 months who attended Ramathibodi and Siriraj Hospitals in Bangkok during two study periods. M. pneumoniae infection was not found in any case from either hospital by serological diagnosis. By the isolation method, C. trachomatis infection was found in 7(16.7%) of 42 patients from Ramathibodi Hospital and 5(21.7%) of 23 patients from Siriraj Hospital with the average male:female ratio of 2.6:1; and 91.7% of the infected cases were under 3 months old. Laboratory diagnosis of respiratory virus infection was performed by indirect immunofluorescence (IIF), isolation, and by antibody detection. Data from Ramathibodi Hospital showed that 11 (24.4%), 4 (8.9%), 3 (6.7%) of the 45 patients were infected by respiratory syncytial virus (RSV), adenoviruses, parainfluenza virus type 3, and some other viruses, respectively; infection rates of 10 (32.3%), 4 (12.9%), 1 (3.2%) and 1 (3.2%) by those viruses respectively, were observed in the 31 patients from Siriraj Hospital.