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 (> or = 40) against avian influenza virus A/H5N2 was significantly greater (P < 0.05) among poultry workers, in comparison to a Japanese healthy population. The geometric mean titers of serum neutralization antibody against A/H5N2 were significantly higher (P < 0.05) among Ibaraki inhabitants and poultry workers (P < 0.0001) when compared to a Japanese healthy population. Seropositivity against A/H5N2 virus was significantly (P < 0.05) associated with age (> or = 50 years 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.

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.

Caregiver burden for impaired elderly Japanese with prevalent stroke and dementia under long-term care insurance system.

BACKGROUND: Limited data are available on caregiver burden for stroke and dementia patients. We examined the associations of prevalent stroke and dementia with family caregiver burden in Japanese general populations. METHODS: A total of 916 Japanese home caregivers, whose family members were covered by long-term care insurance, responded to the caregiver burden questionnaire. The questionnaire included the caregiver's age, sex and employment status, the patient-caregiver relationship, the patient's history of stroke, symptoms of dementia, care levels under long-term care insurance and the Zarit Caregiver Burden Interview. RESULTS: The mean total score from the Zarit Caregiver Burden Interview was 12% higher in patients with stroke than in those without (p = 0.02) and 40% higher in those with dementia than in those without (p < 0.001). Compared with nonstroke patients without dementia, the mean total score was 21% higher in stroke patients without dementia (p = 0.01), 49% higher in nonstroke patients with dementia (p < 0.001) and 55% higher in stroke patients with dementia (p < 0.001). After adjustment for the caregiver's age, sex and employment status, the patient-caregiver relationship, and the patient's care level and community, the higher scores remained statistically significant for nonstroke patients with dementia and for stroke patients with dementia but not for stroke patients without dementia. CONCLUSIONS: Prevalent stroke and, more strongly, dementia were associated with increased family caregiver burden. Among patients with dementia, the presence of stroke did not enhance caregiver burden further.