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Biomedical subjects

K T Goh

Publications and source records attributed to K T Goh.

At least 73 records · Page 4Linked to original sources
PubMed1988

Influenza surveillance in Singapore: 1972-86.

Prospective laboratory surveillance of influenza viruses has been carried out since 1973 in Singapore. The results indicate that antigenic shift variants caused epidemics at various times of the year over this period, whereas drift variants were associated with a regular increase in incidence during the second and fourth calendar quarters. Outbreaks due to influenza A virus occurred every year and to influenza B virus at intervals of 16-24 months. Between outbreaks, viruses belonging to either of the two types could be detected during most months, and certain variants appeared several months before the outbreaks they subsequently caused. The factors that contribute to the seasonal pattern are at present unknown.

Adolescent↗
PubMed1987

Epidemiological characteristics of an institutional outbreak of cholera.

An outbreak of cholera caused by Vibrio cholerae 01, biotype El Tor, serotype Inaba, phage type 4, occurred in an institution for the aged in Singapore in August and September 1984. 96 inmates were infected (21 symptomatic and 75 asymptomatic) and 5 died. The index case was a 72-year-old male inmate who continued to assist in food preparation in the kitchen from the time of onset of diarrhoea until he was seriously ill and hospitalized 4 days later. Another kitchen helper was found to have asymptomatic V. cholerae 01 infection. The infection rate for males was significantly higher than that for females (P less than 0.025), associated with the use of unsanitary toilets. The main mode of transmission was through food contaminated by the 2 kitchen helpers who probably accounted for most of the infections, while poor personal hygiene of the inmates helped to sustain person-to-person spread. The outbreak was confined within the institution as the result of the prompt and effective implementation of control measures.

Aged↗
PubMed1987

Serological survey on dengue virus infection in Singapore.

A serological study on dengue infection conducted in Singapore during the period 1982 to 1984 showed that 54.4% of the healthy population between 6 months and over 50 years of age surveyed possessed no haemagglutination-inhibition antibody to dengue type 2 virus. Children below 10 years of age showed the lowest antibody prevalence and were at the greatest risk, with 96.6% susceptible to infection, whereas virtually all adults over 40 showed evidence of prior dengue infection. The geometric mean titre showed a rising trend indicating continuing acquisition of infection in the older age groups. The seropositivity rate of dengue infection of males was twice that of females. Among the 3 major ethnic groups, no significant difference in seropositivity was noted between the Malays and Indians, but the differences between Malays and Chinese and between Indians and Chinese were statistically significant. The study confirmed that the successful implementation of the nation-wide Aedes control programme is reducing endemic dengue virus transmission in the country.

Adolescent↗
PubMed1987

Epidemiological enquiries into a school outbreak of an unusual illness.

A total of 65 students and one female teacher were afflicted with an unusual illness following alleged inhalation of a 'gas' in the school. The main symptoms were dizziness, chills, nausea, headache, difficulty in breathing and faintness. Initial investigations revealed elevated carboxyhaemoglobin levels (greater than 5%) of 16 hospitalized students. However, no sources of carbon monoxide emission could be detected despite extensive environmental investigations. The outbreak was characterized by the following features: most victims were adolescent girls; there was a high proportion of recurrences; the illness was self-limiting with inconsistent clinical and epidemiological findings; its mode of transmission was associated with antecedent visual observation or verbal information, and it died down immediately after confidence had been restored. A diagnosis of mass psychogenic illness was made. The high-risk students were Malay girls who were from the normal class (for slow learners), engaged in part-time employment and easily influenced by what they had heard or seen.

Adolescent↗
PubMed1987

Epidemiology of viral infections in Singapore.

As Singapore is a densely populated island, and also a major air and sea port, the importation and dissemination of viral infections is facilitated. Respiratory viral infections have the highest prevalence rates, influenza and respiratory syncytial virus (RSV) being the most important ones. Seasonal variation occurs with influenza, RSV and parainfluenza virus type 1 infections. The age distribution and clinical picture associated with infections due to the various respiratory viruses are similar to those reported in other countries. Carrier rates for hepatitis B are high, but differ in the three major ethnic groups, vertical transmission from infected mothers being an important mode of transmission. Outbreaks of hepatitis A have been associated with the consumption of inadequately cooked shellfish. Cytomegalovirus and Epstein-Barr virus infections are acquired early in life and herpes simplex, more slowly. Genital herpes is increasing in incidence. Coxsackievirus A24 and enterovirus 70 have caused major epidemics of acute haemorrhagic conjunctivitis at 5-10 year intervals. Outbreaks of hand, foot and mouth disease due to coxsackievirus A16 have also occurred. With the declining incidence of dengue haemorrhagic fever, the percentage of susceptible individuals in children under 10 years, has increased markedly. Epidemics of rubella which occurred during the past decade, together with immunisation, have increased herd immunity to this virus.

Adolescent↗
PubMed1987

Acute hepatitis A in Singapore: importance of shellfish ingestion in a non-epidemic period.

A case-control study based on 28 serologically confirmed cases of hepatitis A and 42 home contacts with no recent or past evidence of hepatitis A virus (HAV) infection was conducted to determine the importance of shellfish exposure in the transmission of HAV during a non-epidemic period in Singapore. It was found that consumption of partially-cooked cockles (Anadara granosa) was significantly associated with the illness (p less than 0.001). No other types of locally available shellfish including oysters, mussels and clams were incriminated. The public should be constantly reminded to refrain from consuming raw and inadequately cooked bivalve molluscs all the time, and not just during epidemics.

Acute Disease↗
PubMed1987

Immune status of the population to poliovirus infection in Singapore.

A seroepidemiological survey conducted after two decades of mass immunization against poliomyelitis in Singapore showed a high level of herd immunity in the population to all three types of human poliovirus. Neutralizing antibodies to poliovirus 1, 2 and 3 were detected in 93.9-96.7% of the population between 6 months and over 40 years old. Adults above 30 years of age had a relatively high level of susceptibility to poliovirus infection, with 10.2-12% in the over-30-year age group possessing no neutralizing antibody against poliovirus 1, 14.3% in the 40+ age group against poliovirus 2, and 14% in the 30-39-year age group against poliovirus 3. The geometric mean titres showed a general decline among the older age groups. There were no statistically significant differences in the immune status by sex and by ethnic groups (Chinese, Malays and Indians). The importance of maintaining a high coverage of immunization, monitoring the herd immunity of the population to identify high-risk groups, and advising adults travelling to the endemic areas to be immunized against poliomyelitis was stressed.

Adolescent↗
PubMed1987

Water resource development and prevention of malaria.

The construction of dams across the mouths of major tidal rivers in the development of the Kranji Reservoir, Western Catchments Scheme and the Sungei Seletar Reservoir in Singapore created suitable environmental conditions for the propagation of anopheline brackish-water breeders. The employment of foreign contract workers from malarious areas for the projects further increased the potential risk of malaria transmission. However, constant vigilance and environmental management aimed at the permanent elimination of vector breeding habitats, supplemented with chemical control and anti-parasite measures successfully prevented the reintroduction of malaria in these highly receptive and vulnerable areas.

Animals↗
PubMed1987

Epidemiological aspects of an outbreak of dengue fever/dengue haemorrhagic fever in Singapore.

A nation-wide outbreak of 260 cases of DF/DHF with 1 death occurred in Singapore from Apr-Sept 1986. The outbreak originated from 3 separate foci of transmission at the western, south-eastern and north-eastern parts of the island and then spread to other dengue receptive urban and suburban areas. The morbidity rate was highest in young male Chinese adults between 15 and 24 years of age. The outbreak was rapidly brought under control through destruction of adult Aedes mosquitoes, surveys and source reduction of larval breeding habitats, health education and to a certain extent law enforcement. The Aedes population was high in the main foci of transmission although the overall house index was only 1.1. Other factors which could have precipitated the outbreak included waning herd immunity of the human population and continuous introduction of dengue virus into the country.

Aedes↗
PubMed1987

Surveillance of food poisoning and other food-borne diseases in Singapore.

The more important food-borne diseases in Singapore are food poisoning, enteric fever, cholera and hepatitis A. Bacterial food poisoning caused by Staphylococcus aureus, Salmonella and Vibrio parahaemolyticus is prevalent, but chemical poisoning due to ingestion of toxic plants and animals is uncommon. Enteric fevers have been brought under control. An increasing proportion of the cases reported in recent years were imported from Southeast Asia and the Indian subcontinent. Cholera continues to be introduced into the country with sporadic cases reported from time to time. Hepatitis A remains an important food-borne disease involving predominantly the adolescents and young adults. Consumption of raw and partially-cooked cockles has been associated with both sporadic transmission and periodic outbreaks of hepatitis A. Prevention and control strategies implemented include surveillance and outbreak investigation, food control and legislation, health education and maintenance of a high standard of environmental sanitation.

Cholera↗
PubMed1987

A flea-borne outbreak of dermatitis.

In April 1986, an outbreak of pruritic rash occurred among workers in a warehouse in Jurong and affected 18 out of the 46 workers within one week. The rash was papular and distributed mainly over the thighs, abdomen and the upper limbs. Epidemiological investigations were carried out to determine the cause of the outbreak and the mode of transmission. As the warehouse was colonised by a local species of wild birds (Mynahs) and badly littered with bird-droppings during the outbreak period, samples of bird excreta and feathers were sent for identification of tick, mite, flea and other ectoparasites. The aetiology of the outbreak was confirmed when a flea caught from the body of one of the affected workers was identified as Ceratophyllus gallinae (Schrank), a bird-flea. Furthermore, when the bird-droppings were cleaned up and the premises fogged with insecticide and made bird-proof, no further case of dermatitis was reported. This is the first documented report of a bird-flea causing an outbreak of dermatitis in Singapore.

Adult↗
PubMed1987

Antitoxic immunity of the population against diphtheria in Singapore.

A serological study to evaluate the efficacy of the diphtheria immunisation programme in Singapore based on sera collected from 425 healthy persons between 6 months and 40+ years of age showed that 94.6% of the population surveyed possessed protective neutralising antitoxin (greater than or equal to 0.01 IU/ml). No sex or ethnic difference was noted. The most suspectible age-group was adults above 40 years of age in which 14.3% had no protective antitoxic immunity against diphtheria (less than 0.01 IU/ml). The geometric mean titre was generally high with sharp anamnestic type of secondary response elicited by periodic boosters administered. The survey confirmed the efficacy of the childhood immunisation programme which extended from 3 months to 15+ years of age, in maintaining a high level of herd immunity of the population right into adulthood. Further extension of the programme to include routine revaccination of adults was not considered necessary.

Adolescent↗
PubMed1986

Evaluation of a low dose of hepatitis B vaccine given within a childhood immunisation programme in Singapore.

The feasibility of introducing low dose (5 micrograms) hepatitis B (HB) virus vaccination at birth and again 1 and 2 months later as part of an existing primary immunisation programme of childhood, was assessed in 662 healthy newborn Singapore children. The vaccine (B-Hepavac, Menck, Sharp and Dohme) was given to three neonatal groups: those born to HB surface antigen (sAg)-negative mothers, HBsAg-positive/HBeAg-positive mothers and HBsAg-positive/HBeAg-negative mothers. A dose of 5 micrograms was compared in a randomised study with the more usual 10 micrograms dose given at the same intervals. Neonates born to HBsAg-positive/HBeAg-positive mothers were also given hepatitis B immunoglobulin (HBIg) at birth. The 5 microgram dose of vaccine was as immunogenic as the 10 microgram dose in all three groups of children studied. At 1 year, anti-HBsAg seroconversion among infants of antigen-negative mothers was 95.8% for the 5 microgram dose and 91.9% for the 10 microgram dose. Suppression of anti-HBsAg formation was not seen even when maternal anti-HBsAg was present or HBIg given. Among infants born to HBsAg-positive/HBeAg-positive mothers, passive plus active immunisation was 100% protective at doses of 5 micrograms and 10 micrograms vaccine in the newborns who were HBsAg-negative at 24 h. Seroconversion after both the 5 and 10 microgram doses of vaccine was reduced, however, to 88% in each group of infants who were already HBsAg-positive at 24 h of age. Overall, passive plus active immunisation as well as HB vaccine alone (5 micrograms dose), given within the existing but expanded primary immunisation programme of childhood, was effective in preventing infection and the chronic carrier state in newborns exposed to risk of HB virus infection during infancy.

Carrier State↗
PubMed1986

Social and economic aspects of malaria in Singapore.

Singapore is both receptive and vulnerable to the introduction of malaria because of its location in a malarious zone. The social and economic factors that determined the incidence of malaria included rapid urban and industrial developments which created suitable environmental conditions for the breeding of Anopheles vectors, influx of foreign workers from the endemic countries and increased travel to the malarious areas. The public health significance of the interactions of these factors was exemplified by the occurrence of periodic localized outbreaks. The problem of introduction of drug-resistant falciparum malaria by travellers into the country was another matter of concern. However, the health authorities were fully committed in bringing these problems under control, with political support as well as regional and international collaboration. The result of these efforts was realised in 1982 when Singapore was certified malaria-free by the WHO. The strategies implemented included epidemiological and vector surveillance, health education and environmental health supervision of all major development projects in receptive areas.

Disease Outbreaks↗