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Biomedical subjects

K B Chua

Publications and source records attributed to K B Chua.

50 records · Page 3Linked to original sources
PubMed1999

Identification of enterovirus 71 isolates from an outbreak of hand, foot and mouth disease (HFMD) with fatal cases of encephalomyelitis in Malaysia.

Thirteen enterovirus 71 (EV71) isolates were obtained from both fatal and non-fatal infections of patients seen in Peninsula Malaysia and in Sarawak during an outbreak of hand, foot and mouth disease (HFMD) in Malaysia in 1997, with incidences of fatal brainstem encephalomyelitis. The isolates were identified using immunofluorescence staining, neutralization assays, and partial sequencing of the 5' untranslated regions (UTR). Assessment of the potential genetic relationships of the isolates using the partial 5'UTR sequences suggested clustering of the isolates into at least two main clusters. Isolates from Peninsula Malaysia were found in both clusters whereas Sarawak-derived isolates clustered only in cluster II. Isolates derived from fatal infections, however, occurred in both clusters and no distinctive nucleotide sequences could be attributed to the fatal isolates. Examination of the nucleotide sequences revealed at least 13 nucleotide positions in all the isolates which differ completely from the previously reported EV71 5'UTR sequences. In addition, at least 11 nucleotide position differences within the 5'UTR were noted which differentiated cluster I from cluster II. Predicted secondary RNA structures drawn using the nucleotide sequences also suggested differences between isolates from the two clusters. These findings suggest the presence of at least two potentially virulent EV71 co-circulating in Malaysia during the 1997 HFMD outbreak.

5' Untranslated Regions↗
PubMed1999

Viral aetiology of lower respiratory tract infection in young Malaysian children.

OBJECTIVE: To study the viral aetiology of lower respiratory tract infection (LRTI) in young Malaysian children. METHODOLOGY: A retrospective review was performed of LRTI patients aged less than 24 months who were admitted to the University Malaya Medical Centre between 1982 and 1997. Respiratory viruses in their nasopharyngeal secretion were identified by indirect immunofluorescence, viral culture, or both. RESULTS: A total of 5691 children were included in the study. The mean age was 8.6 +/- 6.6 months and the M:F ratio was 1.6:1. The most common diagnosis was pneumonia (52%) followed by bronchiolitis (45%) and croup (2%). Positive viral isolation rate was 22.0%. Respiratory syncytial virus (RSV) was the commonest virus isolated (84%), followed by parainfluenza virus (8%), influenza virus (6%) and adenovirus (2%). Patients with positive virus isolation were younger (7.8 +/- 6.2 vs 8.7 +/- 6.7 months, P = 0.0001) and were more likely to have bronchiolitis. CONCLUSION: Young Malaysian children admitted with LRTI had a 22% viral isolation rate and RSV was the commonest virus isolated.

Bronchiolitis↗
PubMed1999

Molecular detection of enteroviruses from an outbreak of hand, foot and mouth disease in Malaysia in 1997.

Enterovirus 5'UTR sequences were detected by RT-PCR in 22 out of 47 suspected hand, foot and mouth disease (HFMD) patients during an outbreak of the disease with incidences of fatal brainstem encephalomyelitis in Malaysia in 1997. Genetic and phylogenetic analyses of the isolates 5'UTR sequences suggest the presence of predominantly enteroviruses with high sequence similarities to Echovirus 1 and Coxsackievirus A9 in the Malaysian peninsula. No fatal cases, however, were associated with these isolates. The remaining isolates, including all (4/4) isolates of the fatal cases from the Malaysian peninsula and Sarawak shared very high sequence identity with enterovirus 71MS (EV71). These findings suggest that several enteroviruses were circulating in Malaysia during the outbreak period, with only EV71 causing fatal infections.

Base Sequence↗
PubMed1999

Uvulo-palatoglossal junctional ulcers--an early clinical sign of exanthem subitum due to human herpesvirus 6.

A provisional clinical diagnosis of exanthem subitum was made in six febrile infants seen in the Paediatric Unit of Assunta Hospital, Petaling Jaya, Malaysia with uvulo-palatoglossal junctional ulcers prior to the eruption of maculopapular rash. On follow-up, all six infants developed maculopapular rash with the subsidence of fever at the end of the fourth febrile day. Human herpesvirus 6 was isolated from the peripheral blood mononuclear cells during the acute phase of the illness and HHV 6 specific genome was also detected in these cells by nested polymerase chain reaction. All the six infants showed seroconversion for both specific IgG and IgM to the isolated virus. This study suggests that the presence of uvulo-palatoglossal junctional ulcers could be a useful early clinical sign of exanthem subitum due to human herpesvirus 6.

Exanthema Subitum↗
PubMed1999

The association of uvulo-palatoglossal junctional ulcers with exanthem subitum: a 10-year paediatric outpatient study.

A 10-year follow-up of children having exanthem subitum (ES) seen in an outpatient paediatric clinic, Kuala Lumpur, Malaysia shows that uvulo-palatoglossal junctional (UPJ) ulcer is a reliable early clinical sign of ES. During this period, 1,977 children (1,086 males, 891 females) had adequate follow-up from the age of 3 months to 24 months old. 897 children (478 males, 419 females) were noted to have UPJ ulcers. Of these 897 children, 855 (459 males, 396 females) presented with the classical clinical features of ES of maculopapular rash following 3 to 4 days of fever. The positive predictive value and the negative predictive value of UPJ ulcers in the clinical diagnosis of ES are 95.3% and 100% respectively. Among the 855 children with clinical features of ES, a provisional diagnosis of ES could be made in 781 children during the pre-eruptive phase by the presence of the UPJ ulcers. The other 74 children already had the rash at the time of consultation at the clinic. The peak age of occurrence of ES was 6 months old with 98.2% of the total cases of ES seen between the age of 4 and 12 months. There was no significant gender difference in the incidence of ES nor any seasonal variation. Mild to moderate diarrhoea was the other commonly associated clinical feature which usually presented from the third febrile day onwards.

Age Distribution↗
PubMed1999

Colonization and transmission of Ureaplasma urealyticum and Mycoplasma hominis from mothers to full and preterm babies by normal vaginal delivery.

A prospective study was carried out among pregnant women and their newborn babies in the University Hospital, Kuala Lumpur from January 1996 to June 1997. The maternal cervical colonization rates of Ureaplasma urealyticum (UU) and Mycoplasma hominis (MH) were found to be 57.5% and 15.8% respectively while the isolation rates from nasopharyngeal secretions of the newborns were 50.8% for UU and 6.6% for MH. The overall transmission rates were 88.4% for UU and 42.1% for MH. There was no significant difference in the transmission rates of either organism from mothers to their respective newborn babies by the maturity of pregnancy. In preterm babies, the nasopharyngeal isolation rates of UU and MH were not influenced by the babies' gestational age and birth weight nor by the maternal history of abortion or parity. However, there was a tendency for UU to persist in the nasopharyngeal secretion of preterm babies especially those of birth weight below 2 kg. None of the babies contaminated with mycoplasmas at birth developed respiratory symptoms during six to eight weeks of follow-up.

Cervix Uteri↗
PubMed1998

Fatal enterovirus 71 encephalomyelitis.

During an outbreak of hand-foot-mouth disease caused by enterovirus 71 (EV-71) in 1997, 4 children presented with sudden cardiopulmonary collapse and minimal neurologic features. All children received cardiopulmonary resuscitation but died within a few hours of admission. Postmortem studies showed infection by EV-71 with extensive damage to the medulla and pons. We postulate an etiologic link between EV-71 and brainstem encephalomyelitis as the cause of pulmonary edema and death.

Child, Preschool↗
PubMed1998

Isolation and identification of human herpesvirus 7 from an infant with exanthem subitum.

Exanthem subitum (ES) is a common childhood exanthematous disease. In a recent study of ES due to human herpesvirus 6 (HHV 6), we isolated human herpesvirus 7 (HHV 7) from the peripheral blood mononuclear cells (PBMC) of a seven month-old infant with typical symptoms of ES. The identity of the virus was confirmed by indirect immunofluorescence using HHV 7 specific monoclonal antibody and by amplification of the HHV 7 specific genomic sequences using the polymerase chain reaction (PCR). Paired serum samples from the infant showed serological conversion to the isolated virus. The clinical manifestations of ES in this infant appeared to be milder than the classical ES due to HHV 6.

Antibodies, Monoclonal↗
PubMed1998

Ureaplasma urealyticum and Mycoplasma hominis isolation from cervical secretions of pregnant women and nasopharyngeal secretions of their babies at delivery.

BACKGROUND: A prospective study was carried out at the University Hospital, Kuala Lumpur to determine the cervical carriage rate of Ureaplasma urealyticum and Mycoplasma hominis among healthy pregnant women at delivery and the incidence of nasopharyngeal colonisation among their infants. PATIENTS: Sixty mother and baby pairs were examined. RESULTS: Cervical colonisation among the mothers was found to be 56.7% for U.urealyticum and 17.7% for M.hominis. The transmission rate to their infants was 88.2% and 30% for U.urealyticum and M.hominis respectively. CONCLUSION: There was no statistically significant difference in the maternal colonisation rates according to ethnic group, parity and past history of abortion. All U.urealyticum isolates in our study were sensitive to erythromycin but about one-third were resistant to tetracycline and ciprofloxacin and 26.5% were resistant to minocycline.

Chi-Square Distribution↗
PubMed1997

The incidence of human herpesvirus 6 infection in children with febrile convulsion admitted to the University Hospital, Kuala Lumpur.

From October 1996 to March 1997, 31 children with febrile convulsions were admitted to the University Hospital, Kuala Lumpur. Human Herpesvirus 6 (HHV 6) was virologically and/or serologically confirmed to be the cause of the febrile episode in 5 of these children (16.1%). Age, sex and other associated clinical features (diarrhoea, cough, running nose and type of seizure) were not useful in differentiating cases of febrile convulsion due to HHV 6 from those of other aetiology. However, uvulo-palatoglossal junctional ulcers were noted in children in whom the cause of the seizure could be attributed to HHV 6 but not in the remaining cases in the study group. HHV 6 DNA was detected in peripheral blood mononuclear cells from all patients with febrile convulsions attributed to HHV6, and in patients shown serologically to have already been exposed to the virus by nested polymerase chain reaction amplification. Only genotype HHV 6B was detected from patients with seizure due to HHV 6 but both genotype 6A and 6B were detected in the remaining cases studied.

Child, Preschool↗
PubMed1997

Quantification of left ventricular function with thallium-201 and technetium-99m-sestamibi myocardial gated SPECT.

UNLABELLED: Myocardial gated SPECT with 99mTc-sestamibi has been used to quantify left ventricular function. The purpose of this study was to determine if myocardial gated SPECT with 201Tl was possible and reliable to quantify left ventricular function. METHODS: One hundred and four patients referred for a myocardial perfusion study were included. Myocardial gated SPECT acquisition was performed 15 min after the intravenous injection of 111 MBq (3mCi) 201Tl and at 1 hr postinjection of 925 MBq (25 mCi) 99mTc-sestamibi. A commercially available automated myocardial gated SPECT processing software was used. Parameters evaluated were left ventricular ejection fractions (LVEF), end-diastolic volumes (EDV), end-systolic volumes (ESV) and stroke volumes (SV). RESULTS: The correlation between gated SPECT with 201Tl and gated SPECT with 99mTc-sestamibi was: r = 0.93 for LVEF, 0.92 for EDV, 0.96 for ESV and 0.68 for SV. CONCLUSION: Myocardial gated SPECT quantification of left ventricular function with 201Tl was possible and as reliable as gated SPECT with 99mTc-sestamibi. There was excellent correlation between gated SPECT with 201Tl and gated SPECT with 99mTc-sestamibi. In addition to assessment of myocardial perfusion, myocardial function and viability can be quantified in a single gated 201Tl study.

Coronary Disease↗
PubMed1996

Seroepidemiology of human herpesvirus 6 in a population seen in the University Hospital, Kuala Lumpur, Malaysia.

Sera from healthy donors and patients stored over a period of 2 years, aged 1 to 83 years, were examined for reactivity to human herpes virus 6 (HHV-6) by the standard indirect immunofluorescence assay (IFA). Of the 600 serum specimens screened, 502 showed positive reactivity to HHV-6. This gives an overall seropositive rate of 83.7%. There is no significant difference in the overall positive rate between the ethnic groups (Chinese, Malays, Indians) (chi 2 = 0.35 df = 2 p > 0.05). However, there is significant difference in the positive rates at the extreme age groups of 1 year as well as 61 years and above. From birth up to below 1 year of age, the seroprevalence rate was 82%. At one year of age the positive rate decreased to 66% before gradually rising so that the percentage seropositivity of 6 to 10 years old becomes similar to that in older children and adults (11 to 40 years). The positive rate then starts to decline after 40 years of age. Using a standardized scoring system, the corresponding antibody titer was found to be high in the very young population and starts to decline after the age of 15 years. This suggests that in our population group, primary infection occurs mainly in the pediatric age group. It also accounts for the low positive rate in the age group of 61 years and above, as by then the titer had fallen to the level below the detection limits of the assay system.

Adolescent↗
PubMedDate not supplied

Hospitalization of childhood rotavirus infection from Kuala Lumpur, Malaysia.

AIM: To determine the epidemiology of rotavirus gastroenteritis in children admitted to an urban hospital in a developing country from South-East Asia. METHODS: Retrospective review of cases of acute gastroenteritis admitted to the children's ward of the University of Malaya Medical Centre, Kuala Lumpur, Malaysia, between 1996 and 1999. RESULTS: During the study period, 333 cases (24%) of 1362 stool samples, obtained from children admitted with acute diarrhoea, were positive for rotavirus. Acute gastroenteritis constituted 8.2%, and rotavirus infection 1.6% of all the paediatric admissions each year. Of the 271 cases analysed, 72% of the affected population were less than 2 years of age. Peak incidence of admissions was between January to March, and September to October. Dehydration was common (92%) but electrolyte disturbances, lactose intolerance (5.2%), prolonged diarrhoea (2.6%) and cow's milk protein intolerance was uncommon. No deaths were recorded. CONCLUSIONS: Rotavirus infection was a common cause of childhood diarrhoea that required hospital admission in an urban setting in Malaysia.

Acute Disease↗