The purpose of our study was to establish a seasonal model to simulate the oscillation of the number of influenza cases with weather conditions and calendar months in Tokyo, Japan, during the winter season. Surveillance data for influenza in Tokyo was retrieved from the Infectious Agents Surveillance Report, published by the National Institute of Infectious Diseases in Japan. We obtained data for 86 parameters of weather conditions from the Meteorological Agency. The best-fit model was built by multiple regression with stepwise analysis. The reported number of patients with influenza per week was significantly increased with fewer days of maximum temperature ≥10°C per week (T10) and more days of relative humidity <60% per week (S60), adjusted by calendar month, average temperature, and vapor pressure. Annual oscillation of the number of reported influenza cases at the start, peak, and end weeks almost exactly matched the model, although peak levels for each oscillation did not always match. However, this model showed that 81% of the variation among the observed number of influenza cases was explained by a linear relationship with the seasonal parameters utilized. The validity of this model applied to data from 1999 to 2002, showing a 75% correlation. Using this model, if the number of days with both T10 and S60 increased by one per week, the number of influenza cases was simulated to decrease by approximately half. These results suggest that most of the oscillation in the number of influenza cases may be explained using a seasonal model that can simulate the impact of global warming.

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In order to investigate the effects of global warming, we attempted to establish seasonal models to predict fluctuations in rates of herpangina (HA) and hand-foot-mouth disease (HFMD) associated with weather conditions and calendar months in Tokyo, Japan. Surveillance data tracking HA/HFMD incidences in Tokyo was retrieved from the Infectious Agents Surveillance Report, published by the National Institute of Infectious Diseases in Japan. From the Meteorological Agency, we obtained data for 54 weather condition parameters. The annual fluctuations in reported HA cases comprising start, peak, and end weeks almost exactly matched the model, although peak levels for each fluctuation did not always match in HFMD. Furthermore, for the HA model, 88% of the variations among observed HA cases were explained by the linear relationship with the seasonal parameters investigated, which was higher than the 64% observed for the HFMD model. The HA and HFMD models were applied to data from the years 1999 to 2002, and demonstrated correlations of 86% and 64%, respectively. These models predicted that warmer climate conditions would lead to an increased number of HA and HFMD cases. These results suggest that our seasonal models may quantify the dependency of infectious diseases on seasonal parameters and simulate the impact of global warming.

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Methicillin-resistant Staphylococcus aureus (MRSA) continues to be an important nosocomial pathogen. Various hospital-based studies have described the incidence of MRSA and carriage of this organism in health care workers. Recently, even community acquired S. aureus strains have shown resistance to methicillin. This changing epidemiology prompted us to study the nasal carriage of MRSA amongst healthy individuals in a community. A total of 319 nasal swabs were taken from both anterior nares of healthy parents attending a well-baby clinic. Of these, 94 yielded growth of S. aureus (29.4%). Out of these 94 isolates, 17 (18.1%) were found resistant to oxacillin. These strains showed low level resistance only to clindamycin.

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Serum samples from 124 acquired immunodeficiency syndrome (AIDS) hospitalized patients at the Fevers Unit, Korle-Bu Teaching Hospital, Accra, Ghana, were examined by the particle agglutination test for antibodies to human T-lymphotropic virus type 1 (HTLV-1) core proteins. The subjects included 84 males and 40 females, aged 16 to 54 years. Specific antibodies were detected in only 14 out of the 124 sera samples, giving an overall prevalence rate of 11.29%. The incidence was lower in males (5.95%; 5/84) than in females (22.50%; 9/40) (P < 0.05). In both sexes, the age distribution of subjects positive for HTLV- 1 antibodies ranged from 35 to 54 years. The prevalence rate reported herein is too low to suggest an association of HTLV-1 with AIDS, though it may indicate an opportunistic infection of AIDS patients by HTLV-1. Whether HTLV-1 is an underlying disease association or whether HTLV-1 plays some auxiliary role in the acquisition and progression of AIDS remains to be determined.

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Although Listeria monocytogenes infection occurs in sporadic and epidemic forms throughout the world, there are certain countries (especially Asian countries) that have reported only a few cases or failed to report even a single case. During her third visit at 17⁺⁵ weeks of gestation, a 22-year-old primigravida presented with the complaint of an acute painful abdomen, leaking per vaginum and low-grade fever for the 2 preceding days. On ultrasonography, a single live fetus with no amniotic fluid was seen and the pregnancy was therefore terminated. L. monocytogenes was isolated from a high vaginal swab.

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Chlamydia pneumoniae is a common pathogen that causes upper and lower respiratory tract infections and is difficult to isolate from clinical specimens. Recently, we succeeded in isolating the first C. pneumoniae strain in Korea. This study characterizes the morphology, infectivity, and drug sensitivity of the Korean strain, designated LKK-1. Electron microscopy was performed for thin sections, and the infectivity over time was tested by counting the inclusion-forming units every 12 h. The minimum inhibitory concentrations of doxycycline, erythromycin, clarithromycin, ciprofloxacin, and levofloxacin were determined following the standard Japanese method. The elementary bodies of LKK-1 were round, like those in Japanese strain KKpn-1, whereas those of TW-183 have wavy cell membranes and are pear-shaped. The infectivity curve and drug sensitivities of LKK-1 were nearly the same as those of KKpn-1. In conclusion, LKK-1, the first strain from Korea, is similar to the Japanese strain KKpn-1 in terms of morphology, growth, and drug sensitivities, and shows a distinct difference in morphology compared with TW-183. Further studies are needed to elucidate the morphological differences between round strains and classical pear-shaped strains of C. pneumoniae.

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Blood culture isolates of Salmonella enterica serovar Typhi showing high degrees of resistance to ampicillin, chloramphenicol, cotrimoxazole and tetracycline (ACCoT-resistance) transferred their full resistance phenotype to antibiotic-sensitive S. enterica serovar Typhi strains through the primary recipient Escherichia coli C600. Transfer frequencies were 0.80 × 10^-5 and 0.80 × 10^-6, respectively, in the primary and secondary transfer experiments. The Escherichia coli isolates from urinary tract infection cases showing high minimum inhibitory concentration values (μg/ml) to A (2,000-5,000), C (2,000-5,000), Co (250-1,200), and T (500-2,000) also transferred ACCoT-resistance to the antibiotic-sensitive S. enterica serovar Typhi and then to E. coli C600 with transfer frequencies 0.61 × 10^-6 and 0.98 × 10^-5, respectively. Curing experiments revealed the loss of ACCoT-resistance from the original and the transconjugant S. enterica serovar Typhi strains. Results suggest that R-factor from other enteric bacteria is acquired by S. enterica serovar Typhi, and that it (R-factor) is unstable in nature.

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We experienced a case of congenital rubella syndrome (CRS) due to infection after maternal antibody conversion with vaccine. The mother was immunized with rubella vaccine at 14 years of age, and was confirmed as having rubella-specific hemagglutination inhibition (HI) antibody at the 1:16 level both at ages 26 and 30 during preceding pregnancies. At the second week of the third gestation, her second child developed rubella. She did not suffer any symptoms, but was found to have rubella HI antibody at the 1:512 level at 9 weeks of gestation. She delivered a male baby weighing 2,545 g at 38 weeks of gestation. He had congenital pneumonia, patent ductus arteriosus, bilateral cataracts, sensorineural deafness, and periventricular calcification of the brain. The rubella-specific antibody was 1:512 by HI and 10.1 by IgM enzyme-linked immunosorbent assay. According to these observations, he was diagnosed as having CRS. The rubella virus genome was detected in the fluids of the vitreous body using RT-nested PCR. This case emphasizes the importance of double-dose immunization (once in infants and once in young adults) in order to obtain an adequate level of antibody with duration sufficient to ensure the prevention of CRS.

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In this study we lyophilized three types of live attenuated polioviruses (Sabin vaccine strains) and evaluated the lyophilized vaccine viruses’ heat stability. The virus titers were measured after heating at 37°C and 45°C and then compared with the titers of conventional liquid vaccine viruses similarly treated. The results showed that lyophilization, while slightly reducing vaccine virus titers, had a far greater sparing effect on subsequent heat inactivation of lyophilized vaccine viruses, thus demonstrating its validity for the improvement of the vaccine.

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We encountered a 12-year-old girl, who had contracted food-borne botulism, and subsequently suffered from obstinate constipation for more than half a year. Even on hospital day 122, Clostridium botulinum and its toxin were detected in her stool specimens. The potency of the toxin of the blood serum sampled before treatment was 20 mouse minimum lethal dose per ml. The toxin in the blood had a molecular size equivalent to that of type A botulinum neurotoxin. On hospital day 250, the patient’s serum detoxified type A neurotoxin. We confirmed that the patient had food-borne botulism caused by C. botulinum type Ab, followed by intestinal colonization-type botulism.

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