Surveillance of acute flaccid paralysis in Hong Kong: 1997 to 2002.

OBJECTIVES: To describe the characteristics of patients reported with acute flaccid paralysis between 1997 and 2002, and to evaluate the performance of the acute flaccid paralysis surveillance system using indicators recommended by the World Health Organization. DESIGN: Retrospective study. SETTING: Department of Health, Hong Kong. PARTICIPANTS: Children aged younger than 15 years who were reported to the Department of Health between 1997 and 2002 with acute flaccid paralysis. RESULTS: Of 120 children with acute flaccid paralysis reported between 1997 and 2002, 42% were younger than 5 years of age. None of the cases were acute poliomyelitis or polio-compatible. A neurological cause was identified in 67.5% of cases, of which the most common was Guillain-Barre syndrome (42%), followed by transverse myelitis (15%). All except one of the performance indicators consistently met World Health Organization requirements and thus demonstrated the effectiveness of the acute flaccid paralysis surveillance programme. The acute flaccid paralysis notification rate consistently exceeded 1.0 per 100 000 population below 15 years of age. The requirement for adequate stool investigation was the single indicator that did not satisfy World Health Organization requirements. This highlighted the importance of maintaining physicians' awareness of acute flaccid paralysis surveillance. CONCLUSION: Hong Kong should remain vigilant for acute flaccid paralysis. The effective surveillance system and its evaluation may serve as a model for surveillance of other infectious diseases.

Consensus statement on iodine deficiency disorders in Hong Kong.

This article reviews the available data on the study of iodine deficiency disorders in Hong Kong and to discuss the approach towards preventing such disorders in Hong Kong. The importance of iodine and iodine deficiency disorders is described, and the available data on the dietary iodine intake and urinary iodine concentration in different populations of Hong Kong are summarised and discussed. Dietary iodine insufficiency among pregnant women in Hong Kong is associated with maternal goitrogenesis and hypothyroxinaemia as well as neonatal hypothyroidism. Borderline iodine deficiency exists in the expectant mothers in Hong Kong. Women of reproductive age, and pregnant and lactating women should be made aware and educated to have an adequate iodine intake, such as iodised salt, as an interim measure. A steering group involving all stakeholders should be formed to advise on the strategy of ensuring adequate iodine intake, including universal iodisation of salt in Hong Kong. Continuous surveillance of iodine status in the Hong Kong population is necessary.

Secular trend in the sexual maturation of southern Chinese girls.

In 1993, a cross-sectional study of sexual maturation of normal Chinese schoolgirls was performed in Hong Kong. The aim of the study was to obtain an up-to-date reference for normal pubertal development in Chinese girls. Breast development was assessed in 3749 girls aged 7-19 y, and pubic hair rating was assessed in 3745 girls. Menstrual status was recorded in 6467 girls over 6 y of age. The median age of onset of puberty as indicated by breast stage II or above was 9.78 (95% CI 9.70-9.85) y. The median age of onset of pubic hair development was 11.64 (95% CI 11.56-11.72) y. The median age of menarche was 12.38 (95% CI 11.98-12.78) years. Percentile values for the age at which each puberty staging appeared were constructed and incorporated into the height-for-age charts. When comparison is made with similar studies done in 1962 and 1979, a significant downward secular trend in sexual maturation is observed (p < 0.01). Except for breast development the downward secular trend in sexual maturation appears to be diminishing and may be coming to a halt in the Chinese girls in Hong Kong. Their median ages of sexual maturation are now among one of the earliest medians recorded in the world population studied.

Clustering of childhood leukaemia in Hong Kong: association with the childhood peak and common acute lymphoblastic leukaemia and with population mixing.

Incidence data of childhood leukaemia (CL) in Hong Kong (1984-90) have been analysed for evidence of variation between small areas. All cases (n=261) were classified by morphological cell type, with the majority (n=205) being acute lymphoblastic leukaemia (ALL), and haematological review has permitted immunophenotypic classification for 73% of these. The data have been examined for evidence of spatial clustering within small census areas (TPUs) and for association with population mixing, with attention focused on those subgroups (especially the childhood peak of ALL--taken here to be diagnoses in children from 24 months up to the seventh birthday--and common ALL) which, it has been hypothesized, may be caused by unusual patterns of exposure and response to common infections. For the whole of Hong Kong, there was evidence of spatial clustering of ALL at ages 0-4 years (P = 0.09) and in the childhood peak (P<0.05). When these analyses were restricted to TPUs where extreme population mixing may have occurred, overall incidence was elevated and significant evidence of clustering was found for ALL (P<0.007) at these ages and for the common ALL in the childhood peak (P = 0.032). Replication of the analyses for subsets of leukaemia that were not dominated by the childhood peak of ALL found no evidence of clustering. This is the first investigation of an association between population mixing and childhood leukaemia in Asia and the first to include clustering and to consider particular subsets. The results are supportive of the 'infectious' aetiology hypothesis for subsets of childhood leukaemia, specifically common ALL in the childhood peak.

Resurgence of cholera in Hong Kong.

Cholera is one of the three diseases subject to the International Health Regulations. After a period of over 30 years, the seventh pandemic of cholera, which started in South East Asia in 1961, still shows no sign of a decline. On the contrary, it has increased its severity and invaded many other countries in Africa and Latin America. In the last two years, there has been a recrudescence of the disease in South East Asia and Western Pacific Regions. The discovery of a new strain of Vibrio cholerae 0139 in these regions is causing concern in view of its potential to cause major epidemics and higher mortality. Hong Kong had two intensive outbreaks of cholera in the last two years. The cause of these outbreaks was not clear, but adverse environmental conditions and increasing pollution of coastal waters have been implicated. The spread of cholera knows no geographical boundaries. There is a need for intensified efforts among health authorities in the affected areas to prevent the international spread of the disease.

Secular changes in standing height, sitting height and sexual maturation of Chinese--the Hong Kong Growth Study, 1993.

In 1993 a territory-wide cross-sectional growth survey on 25,000 Chinese children from birth to 18 years was performed in Hong Kong. Compared to the last growth survey in 1963, definite secular changes were observed. There was an increase of final adult standing height of 3.6 cm in boys and 2.7 cm in girls, in which 1.8 cm and 0.5 cm respectively for boys and girls was accounted for by the sitting height. Thus most of the height increase had occurred in the leg length in girls, but in boys only half of it. The height difference was more marked during the pubertal years because secular change had brought about an earlier sexual maturation, including an advancement of median menarcheal age by 0.5 year, coupled with an earlier growth spurt. This paper also provides the first growth standards for Chinese from birth to 18 years, with percentile charts on both standing height and sexual maturation in boys and girls.

Cytogenetics and immunophenotypes of childhood acute lymphoblastic leukemia in Hong Kong.

We present the cytogenetics and immunophenotypes of 55 cases of childhood acute lymphoblastic leukemia in Hong Kong. Although the pattern of immunophenotypes is similar to that of the west, hyperdiploidy is rarely observed locally. Our preliminary analysis also reveals some new translocations.

Defective B-cell and regulatory T-cell function in Wiskott-Aldrich syndrome.

We report two Chinese boys with Wiskott-Aldrich syndrome presenting with gastro-intestinal bleeding, eczema and recurrent infection. They had thrombocytopenia and the mean platelet volume was small. Serum IgG and IgA were elevated and lymphocyte proliferation in response to phytohaemagglutinin, concanavalin A and pokeweed mitogen was defective. Despite documented herpes simplex virus type 1 and cytomegalovirus infection in one patient, he did not mount any humoral response. The generation of antibody-secreting cells in response to pokeweed mitogen was markedly defective in a plaque-forming cell assay. Both patients' regulatory T-cell and B-cell functions were defective in this assay. The genetic defect in Wiskott-Aldrich syndrome therefore affects T-cells, B-cells and platelets.

Effect of high ambient temperature on the kinetics of the pupillary light reflex in healthy volunteers.

Miotic responses to brief light stimuli were studied in healthy volunteers under two ambient temperature conditions, 22 degrees C and 40 degrees C. The latency and amplitude of the light reflex did not differ between the two conditions, but the recovery time of the reflex was significantly shorter under the 40 degrees C condition than under the 22 degrees C condition. The results are consistent with the hypothesis that exposure to high ambient temperature results in an increased sympathetic drive to the iris dilator muscle but does not influence the parasympathetic light reflex.

Typhoid fever in Hong Kong children.

Experience with typhoid fever in 111 children over a 5-year period was reviewed. There were 66 boys and 45 girls, ranging in age from 1 to 11.5 years. The symptoms of typhoid fever were quite non-specific. Fever was the most common presenting symptom (in 98.3%). Other common presenting features were diarrhoea (25.7%), constipation (22%), vomiting (21.1%), cough (25%), abdominal pain (27.5%), headache (9.2%), epistaxis, meningism and convulsions. Rose spots were detected in 20% of cases, occurring mainly during the first 2 weeks of illness. Significant Widal reactions were present in 84.7% of cases. Blood and stool cultures were positive in 57% and 44% of cases, respectively. Peripheral blood white cell counts were not found to be of great diagnostic value. Chloramphenicol remained the drug of choice in the treatment of typhoid fever. It was more effective than ampicillin or co-trimoxazole. Complications were uncommon, occurring in only two patients. There were two deaths; both were admitted late and in moribund state. Early diagnosis and treatment is vital in typhoid fever and, as the presenting features are non-specific, a high index of suspicion is required.

Acute viral hepatitis: aetiology and evolution.

Over a period of three and a half years, 348 consecutive children with acute hepatitis were studied. There were 205 boys and 143 girls aged from 3 months to 12 years old. The most common type was hepatitis A, of which there were 281 cases, 81% of the total; there were 41 in the under 4 years old age group (63% of that group), 99 in the 5-8 year old age group (87% of that group) and 141 in the 8-12 year old age group (83% of that group). Hepatitis B occurred in 29 (8% of the total), and non-A, non-B hepatitis occurred in 35 (10%). All the children with hepatitis A and all but one with hepatitis B recovered. There were three deaths from fulminant hepatitis, one in the group with hepatitis B and two with non-A, non-B. Clearance of the hepatitis B surface antigen was fast, by six months 26 patients having cleared the antigen and 21 (77%) being positive for hepatitis B surface antibody. One patient became a carrier of hepatitis B surface antigen.

Diagnostic value of the Widal test in childhood typhoid fever.

The usefulness of the Widal test in diagnosing childhood typhoid fever in endemic areas was investigated. The test was done on 150 children with other febrile illnesses and 98 bacteriologically proved cases of typhoid fever. Of the 150 children with nontyphoidal fever, only one had an H agglutinin titer of 1:50. Using an H or O agglutinin titer of 1:50 or more as a criterion for diagnosis, a positive Widal test was found in 88% of typhoid fever cases on the first occasion on which the test was done. If the test was repeated at least 94% of the typhoid cases had a significant result. The Widal test is a useful diagnostic test in children in endemic areas, provided interpretation of the test is made against background information relating to agglutinin levels in normal children in the region.

Pattern of glomerulonephritis in Chinese population: the effect of renal biopsy on the therapeutic decision.

A retrospective analysis of 190 consecutive renal biopsies was undertaken to assess the pattern of glomerulonephritis in Chinese, and the role of renal biopsy in paediatric nephrology. Minimal change nephropathy, IgA nephropathy and membranous nephropathy comprised 41%, 16% and 13% of primary glomerular diseases, respectively. Minimal change nephropathy accounted for only 61% of patients with idiopathic nephrotic syndrome. In 76 patients the provisional clinicopathological diagnosis was shown to be incorrect or uncertain, and correct diagnosis was made solely on histological examination. In 47 cases a substantial change in therapy occurred on the basis of biopsy results. These data suggest that the practice of renal biopsy in paediatric nephrology performed appropriately in carefully selected patients is a useful procedure.

A prospective study on the intrauterine growth of Hong Kong Chinese babies.

A prospective study on the birth weight, crown-heel length and head circumference of 8,445 singleton Chinese newborn infants born between 27 and 42 weeks of gestation was conducted in three major regional maternity units in Hong Kong over a 3 1/2-year period. The data were used to construct centile charts for the intrauterine growth of each physical measurement. By careful gestational assessment of the infants, primary exclusion of pregnancies complicated by abnormal fetal or maternal conditions that might have affected fetal growth together with infants of doubtful maturity, these curves depict more accurately the prenatal growth of Chinese infants than those previously published in studies on similar populations of infants. Chinese infants, as shown by the findings of the present study, are similar in their mean weight to Japanese infants and American infants in Denver but are lighter than British and Australian infants, as well as American infants born at sea level.

Loperamide associated necrotising enterocolitis.

Two cases of necrotising enterocolitis (NEC) occurring in infants beyond the neonatal period were reported. They did not have any predisposing factors to NEC but both had paralytic ileus after loperamide therapy for their mild diarrhoea prior to the onset of NEC. The possible role of loperamide in the pathogenesis of NEC was discussed.

Characteristics and distribution of beta thalassemia haplotypes in South China.

Eleven restriction site polymorphisms in the beta-globin gene cluster were determined in 48 Chinese with homozygous beta-thalassemia and their parents. Seven haplotypes were identified as associated with the beta thal chromosome and 25 with the beta A chromosome. The distribution of the various beta thal haplotypes in different regions of South China was mapped and discussed in relation to prenatal diagnosis and migration of the Chinese people.

Myasthenia gravis in Chinese children.

A clinical study of 50 Southern Chinese myasthenic children observed for periods of two to 18 years (six years on average) revealed manifestations different from those of caucasian patients. Onset was early, at an average of 4.8 years. 82 per cent had ocular myasthenia. Ophthalmoplegia followed ptosis between three months and 10 years later. Additional facial and isolated limb-muscle fatigability developed in only 6 per cent within three months to 3 1/2 years. Only 12 per cent developed generalized myasthenia. Although extension from ocular to the generalized form did not occur later than 20 months after onset, a deterioration in ocular symptoms, without extension into generalized myasthenia, occurred in nine of 18 children during adolescence. Ptosis and generalized myasthenia responded better to anticholinesterase and/or prednisone. Ophthalmoplegia was difficult to treat. The natural clinical course was benign. Spontaneous remission occurred in 62 per cent of cases, but 54.8 per cent of these relapsed, all confined to ocular muscles. Although there was no familial occurrence of myasthenia gravis, an association was found between myasthenia and thyroid disorders in some patients and their relatives. The association with HLA BW46 antigen was striking. Acetylcholine receptor antibodies were absent in the majority, but mildly elevated titres were found in three of five patients whose ocular symptoms deteriorated during adolescence, without extension into generalized myasthenia.

BamH I polymorphism in the Chinese: its potential usefulness in prenatal diagnosis of beta thalassaemia.

The prevalence of the BamH I site 3' to the beta globin gene in Chinese people was determined in 123 normal subjects, 40 patients with heterozygous beta thalassaemia, and 25 patients with homozygous beta thalassaemia. The site was present in 71.1% and absent in 28.9% of the chromosomes carrying normal beta genes. All 25 patients with beta thalassaemia major had the site. This BamH I polymorphism may be used for prenatal diagnosis in about 29% of the pregnancies at risk.