BACKGROUND: Influenza virus is well known to cause recurrent epidemics almost every winter. However, information regarding the epidemiologic pattern of influenza virus in Korea is limited. In this study, the period of influenza virus isolation each year (1990 ~1998), influenza virus types and subtypes, and clinical features in children with influenza virus infection were evaluated. METHODS: Epidemiology of influenza virus was studied in children with lower respiratory tract infections admitted to the Seoul National University Children's Hospital during the period from 1990 through 1998. Influenza viral infection was diagnosed by viral culture in LLC-MK2 and MDCK cells and/or indirect immunofluorescent staining method of nasal aspirates. Isolated influenza A viruses were subtyped by indirect immunofluorescent staining method using monoclonal antibodies, which react specifically to H1 or H3 antigen. RESULTS: Influenza A virus was identified in 76 cases and influenza B virus in 25 cases. Of 62 strains of subtyped influenza A virus, 7 were H1 subtypes and 54 strains were H3. The occurrence of influenza viral lower respiratory tract infection peaked in infants and children between 6 months and 5 years of age (65%). Pneumonia was the most common manifestation (73.3%) and others were bronchiolitis (14.4%), croup (8.2%), and tracheobronchitis (4.1%). Influenza A virus was isolated every winter season. H1 subtype was detected only during 90~91 and 91~92 seasons, while H3 subtype was detected every season. Influenza B virus was isolated every 2 years, i.e., during 90~91, 92~93, 94~95, and 96~97 seasons. The period of influenza virus isolation and its peak time varied each season. The first recognized influenza activities were 4 times each in November and December, respectively, among the 8 seasons. CONCLUSION: The data show that influenza activity in Seoul, Korea, begins early in winter months and lasts for a long duration. These data may have implications in vaccination policy.
Antibodies, Monoclonal ; Bronchiolitis ; Child ; Croup ; Epidemiology* ; Humans ; Infant ; Influenza A virus ; Influenza B virus ; Influenza, Human* ; Korea* ; Madin Darby Canine Kidney Cells ; Orthomyxoviridae* ; Pneumonia ; Respiratory Tract Infections ; Seasons ; Seoul* ; Vaccination

PURPOSE: To decide diagnostic titer in a single determination of antibody by indirect particle agglutination test and to characterize the occurrence of Mycoplasma pneumoniae during a 9 year-period in Seoul. METHODS: M. pneumoniae pneumonia diagnosed serologically at the Seoul National University Children's Hospital from 1986 to 1995 were reviewed, retrospectively. Antimycoplasma antibody was measured by indirect particle agglutination test. Diagnosis was based on 4 fold-rise or single high titer. Single diagnostic titer was set up by the value greater than the 90th percentile of the titer at one year of the children who initially had 4 fold-rise or > or =160. RESULTS: The geometric mean titer and the 90th percentile at 1 year of the 15 children who initially had antibody titer > or =160 or 4 fold-rise were 122 and 639, respectively, and single diagnostic titer was established as > or =640. A total of 126 childern were included by our diagnostic criteria. Male and female ratio was 1.17:1 and the mean age was 6 years 4 months. Pneumonia by M. pneumonuae occurred every years during the study period showing increased cases every 3 years. In the epidemic years, the cases occurred in late spring, summer and early fall. CONCLUSIONS: It is concluded that the occurrence of Mycoplasma pneumoniae pneumonia in Seoul from 1986 to 1995 was characterized by epidemics every 3 years as well as its endemicity.
Agglutination Tests ; Child ; Diagnosis ; Epidemiology ; Female ; Humans ; Korea* ; Male ; Mycoplasma pneumoniae* ; Mycoplasma* ; Pneumonia* ; Pneumonia, Mycoplasma* ; Retrospective Studies ; Seoul*

PURPOSE: Acute lower respiratory tract infections(LRIs) are an important cause of pediatric morbidity and mortality. Causes of acute LRI in infants and children include bacteria, mycoplasma and respiratory viruses. Understanding of the epidemiology, etiology and clinical features of acute viral LRI is essential to improve the methods of prevention, diagnosis and management of these infections. METHODS: Viral etiologic agents and clinical features of acute viral LRI were studied from November 1990 through April 1994 in apparently healthy children. Nasal aspirates were collected from 334 children, who visited or admitted to Seoul National University Hospital due to acute LRI. Viral agents were detected by virus isolation and/or antigen detection by indirect immunofluorescent staining. Medical records of children with proven viral LRIs were reviewe retrospectively. RESULTS: 1) One or more viral agents were identified in 162 cases(48.45%). 2) The pathogens identified were RSV(54.6%), adenovirus(12.8%), parainfluenza virus type 3(12.1%), influenza A virus(8.5%), parainfluenza virus type 1(5.7%), influenza B virus(1.4%), parainfluenza type 2(1.4%) and mixed(two) viruses(3.5%). 3) Mean age was 15 months and acute viral LRIs occurred mostly in the first two years of life(82%). 4) Clinical patterns of viral LRI were pneumonia(45%), bronchiolitis(32%), croup(13%) and tracheobronchitis(2.1%). 5) Forty-three percents of febrile patients had fever of 39 degrees C or more and 44.5% had fever for 5 days or more. 6) Leukocytosis and increased CRP(more than 3+) were detected in 23% and 16%, respectively. 7) The major radiologic features are parahilar peribronchial infiltration, overaeration and consolidation. CONCLUSIONS: We studied the etiologic agents and clinical features of acute viral LRI in apparently healthy children, the results of which may be helpful to the clinicians and further studies are needed for prevention and treatment of acute viral LRI.
Adenoviridae ; Bacteria ; Child* ; Diagnosis ; Epidemiology ; Fever ; Humans ; Infant ; Influenza, Human ; Leukocytosis ; Medical Records ; Mortality ; Mycoplasma ; Orthomyxoviridae ; Paramyxoviridae Infections ; Respiratory Syncytial Viruses ; Respiratory System* ; Respiratory Tract Infections* ; Retrospective Studies ; Seoul

BACKGROUND: With the improvement of sanitary conditions, epidemiologic features and relative frequency of serogroups of salmonella have changed in developed countries. Also there are increasing reports on occurrence of multidrug-resistant salmonella infections. To investigate such changes in Korean children, we retrospectively evaluated epidemiologic features of salmonellosis and antibiotic resistance pattern. METHODS: Medical records of patients, whose blood or stool culture yielded Salmonella sp. were reviewed. Then serogroup, monthly occurrence, clinical syndromes, and antibiotic resistance were evaluated. RESULTS: During the period from January 1986 to December 1995, 166 cases of salmonellosis had been admitted to the Seoul National University Children's Hospital. Group B salmonella was most frequently isolated (48.8%), followed by non-typhoidal group D, group C, and Salmonella typhi. S. typhi was frequently isolated from blood, in contrast with other serogroups from stool. The isolation of S. typhi has been decreasing, while that of non-typhoidal group D and group B has been increasing in the nineties. Forty-two percent were isolated from July to September. Group B was responsible for 54% of the gastroenteritis cases. Among the cases presenting with fever without a primary focus, S. typhi was isolated from blood in 16 cases and group B from blood or stool in 10 cases. Sixty- eight percent of gastroenteritis occurred in children of 2 years or below in age, while most cases of enteric fever occurred in school-age children. Group D strains including S. typhi were susceptible to most antibiotics, such as ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, ciprofloxacin, and ceftriaxone, but more than half of group B strains were resistant to ampicillin and chloramphenicol. CONCLUSION: The occurrence of typhoid fever has been decreasing markedly, but salmonella gastroenteritis by group B and non-typhoidal group D has been increasing in the nineties. Resistance to the primary antibiotics used for the treatment of salmonellosis was observed in the group B strains.
Ampicillin ; Anti-Bacterial Agents ; Ceftriaxone ; Child* ; Chloramphenicol ; Ciprofloxacin ; Developed Countries ; Drug Resistance, Microbial ; Fever ; Gastroenteritis ; Humans ; Medical Records ; Retrospective Studies ; Salmonella ; Salmonella Infections* ; Salmonella typhi ; Seoul ; Trimethoprim, Sulfamethoxazole Drug Combination ; Typhoid Fever