Kazutoshi Nakashima

Human H5N2 Avian Influenza Infection in Japan and the Factors Associated with High H5N2-Neutralizing Antibody Titer

Background H5N2 avian influenza virus infection of humans has not been reported thus far. The first H5N2 avian influenza infection of poultry in Japan occurred in Ibaraki. Methods The subjects were workers at 35 chicken farms in Ibaraki Prefecture, where the H5N2 virus or antibody was isolated from chickens. None of the subjects exhibited influenza symptoms. The H5N2-neutralizing antibody titers of the first and second paired sera samples were compared. To investigate the possible factors for this increase, the H5N2-neutralizing antibody titer (1:40 or more) was calculated for the second samples. A logistic regression analysis was performed to examine the association of these factors with H5N2-neutralizing antibody positivity. Results We performed Wilcoxon matched-pairs signed-ranked test on data collected from 257 subjects, and determined that the H5N2 antibody titers of the second paired sera samples were significantly higher than those of the first samples (P < 0.001). The H5N2 antibody titers of paired sera of 13 subjects without a history of seasonal influenza vaccination within the previous 12 months increased 4-fold or more. The percentage of antibody positivity was 32% for subjects with a history of seasonal influenza vaccination (28% of all subjects) and 13% for those without a history of the same. The adjusted odds ratio of H5N2-neutralizing antibody positivity was 4.6 (95% confidence interval: 1.6-13.7) for those aged over 40 and 3.1 (95% confidence interval: 1.6-6.1) for those with a history of seasonal influenza vaccination within the previous 12 months. Conclusion The results suggest that this may have been the first avian influenza H5N2 infection of poultry to affect humans. A history of seasonal influenza vaccination might be associated with H5N2-neutralizing antibody positivity.

Risk factors for severe hand foot and mouth disease.

Background:u2002 Hand foot and mouth disease (HFMD) and herpangina are enteroviral infectious diseases caused mainly by Coxsackie virus A (CA) or enterovirus 71 (EV71). From 2000 to 2002, many complicated cases were reported in Japan, therefore a nationwide questionnaire survey was carried out to assess the situation. The subjects were patients with HFMD or herpangina, or other enterovirus infection from 2000 to 2002, who were either hospitalized over 24u2003h or who died. The response rates were 41.3% in 2000 and 2001 and 31.6% in 2002. The survey period included the year 2000, when HFMD epidemics due to EV71 occurred. To examine risk factors causing complications of enterovirus infection, severe cases of HFMD were focused on.

Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000.

OBJECTIVEnTo identify risk factors for infection and severe illness due to Chlamydia pneumoniae.nnnMETHODSnTo identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study.nnnSETTINGnA nursing home providing long-term and day care services for elderly patients in Japan.Participants. Fifty-nine residents and 41 staff members of a nursing home.nnnRESULTSnThe attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P=.04).nnnCONCLUSIONSnC. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.

Epidemiological and genetic analyses of a diffuse outbreak of hepatitis A in Japan, 2010.

BACKGROUNDnHepatitis A virus (HAV) is still one of the most common causative agents of acute hepatitis in Japan. Although a relatively small number of annual acute hepatitis A cases (approximately 100-150, 0.78-1.17 per million) were recently reported, a larger number of cases (346, 2.71 per million) were reported in 2010.nnnOBJECTIVESnTo investigate the causes of the 2010 HAV resurgence in Japan by using molecular epidemiological and genetic analyses.nnnSTUDY DESIGNnHAV specimens were obtained from 61 cases from 22 different prefectures. These viral specimens were genotyped by PCR amplification and sequencing of the VP1/2A region of HAV genome.nnnRESULTSnPhylogenetic analysis revealed that 61 HAV strains could be divided into three genotypes: IA (44 cases), IB (1 case) and IIIA (16 cases). The IA genotype consisted of two genomic sub-lineages. The sequences of one of the two IA sub-lineages (corresponding to 31 cases) were very similar, 26 of these 31 isolates had 100% identity. The other IA sub-lineage corresponded to strains endemic to Japan. The sequences of Japanese IIIA strains were similar to those of strains that caused a large epidemic in the Republic of Korea from 2007 to 2009.nnnCONCLUSIONSnThe resurgence of HAV in 2010 can be attributed to importation of two newly emerged HAV genotypes.

Surveillance of hand, foot, and mouth disease for a vaccine

262 www.thelancet.com/infection Vol 14 April 2014 importance of long-term and dependable surveillance. Local data are crucial, but they need mechanisms for their accurate collection—a special challenge in less well resourced or organised health services. Everywhere, reliable data are essential to drive public-health policy. Collecting it properly needs to become part of the culture of all health professions and organisations.

Serological survey of avian H5N2-subtype influenza virus infections in human populations

To investigate the distribution of antibodies against H5N2 influenza virus in humans living in Ibaraki prefecture, Japan, 266 single serum samples were collected to perform serological tests. Results were compared to investigate the relationship between positive results and several factors. The number of positive serum neutralization antibody titers (≥40) against avian influenza virus A/H5N2 was significantly greater (Pxa0<xa00.05) among poultry workers, in comparison to a Japanese healthy population. The geometric mean titers of serum neutralization antibody against A/H5N2 were significantly higher (Pxa0<xa00.05) among Ibaraki inhabitants and poultry workers (Pxa0<xa00.0001) when compared to a Japanese healthy population. Seropositivity against A/H5N2 virus was significantly (Pxa0<xa00.05) associated with age (≥50xa0years old) in poultry workers. These results suggest that seropositivity against H5N2 virus in Ibaraki specimens is significantly higher than those of a Japanese healthy population and that the surveillance of avian influenza viruses is very important to evaluate the invasion or emergence of new pandemic influenza viruses from species other than humans.

Ongoing increase in measles cases following importations, Japan, March 2014: times of challenge and opportunity.

WPSAR Vol 5, No 2, 2014 | doi: 10.5365/wpsar.2014.5.2.001 www.wpro.who.int/wpsar 1 a Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan. b Department of Virology 3, National Institute of Infectious Diseases, Tokyo, Japan. Submitted: 1 April 2014; Published: 16 May 2014 doi: 10.5365/wpsar.2014.5.2.001 Ongoing increase in measles cases following importations, Japan, March 2014: times of challenge and opportunity