Hepatitis B Virus Infection Among Residents of a Nursing Home for the Elderly: Seroepidemiological Study and Molecular Evolutionary Analysis Fuminaka Sugauchi, Masashi Mizokami*, Etsuro Orito, Tomoyoshi Ohno, Hideaki Kato, Mina Maki, Hiko Suzuki, Kousei Ojika, and Ryuzo Ueda Second Department of Internal Medicine and Blood Transfusion, Nagoya City University Medical School, Nagoya, Japan A seroepidemiological study of HBV infection was carried out to investigate the seropreva- lence of hepatitis B surface antigen (HBsAg) and the transmission routes of hepatitis B virus (HBV) infection among residents of a nursing home for the elderly. HBV serum markers were examined in 119 residents and 71 healthcare workers in the institution, as also in 1330 healthy subjects from the same geographical area, as the control group. HBsAg was detected in 6 (5%), 0 and 20 (1.5%) residents, healthcare workers and healthy subjects, respectively. Four resi- dents (A–D) who had HBV-DNA in the serum were studied by molecular evolutionary analy- sis. The strains derived from residents A, B and D were clustered together within a close range of evolutionary distances. Residents B and D, who were not positive for HBsAg at the time of admission to the institution, subsequently be- came HBsAg-positive asymptomatic carriers. These results suggested intrainstitutional trans- mission of HBV in the nursing home for the el- derly, and confirmed that the source of transmis- sion of HBV to residents B and D was resident A who was positive for HBsAg. Residents in a nursing home for the elderly should be consid- ered as being a high-risk group for HBV infec- tion, and vaccination against HBV of these groups is recommended. J. Med. Virol. 62:456– 462, 2000. © 2000 Wiley-Liss, Inc. KEY WORDS: elderly; phylogenetic tree analysis; HBsAg; transmission INTRODUCTION Long-term residents of semi-closed institutions, such as nursing homes for the elderly are considered to be at increased risk for outbreaks of various infectious dis- eases. Several decades ago, institutions for the elderly living in closed environments were identified as being at increased risk for hepatitis B virus (HBV) infection as a result of frequent contact with blood and body fluids, a direct consequence of nursing care [Braconier and Nordenfelt, 1972; Chiaramonte et al., 1982]. Sev- eral studies have recognized recently the epidemiology of HBV infection in such institutions in Europe and America [Foreani et al., 1992; Simor et al., 1992; Nor- man et al., 1999]. Similar data, however, in long-term care institutions have not been reported in Japan and few studies have reported the infection routes in such institutions by genetic analysis [Kondo et al., 1993]. In this study, a seroepidemiological study of HBV infec- tion is described among residents of a nursing home for the elderly in Japan and elucidate the source of trans- mission of HBV among the residents of the institution using molecular evolutionary analysis based on the pre-S1 to S and the S gene nucleotide sequences of the HBV. MATERIALS AND METHODS Patients In August 1999, 119 residents (29 males and 90 fe- males) living in a nursing for the elderly with continu- ous care accommodation in Nagoya, Japan were stud- ied. Many of the residents suffered from sequelae of cerebral vascular disease, Parkinson disease or senile dementia, and required nursing assistance for daily ac- tivities. Residents of this institution were of advanced age who could not be supported by nursing assistance by their families in their own homes. The institution was built in April 1985. Men and women lived in the same building. The duration of stay at the institution ranged from 1 to 14 years (mean 66.4 months) among the 119 residents. Most of the medical equipment used Grant sponsor: Ministry of Education, Science and Culture of Japan; Grant number: 11691222. The international DNA database accession number of the se- quence reported in this paper is AB042244 through AB042247. *Correspondence to: Masashi Mizokami, Second Department of Medicine/Blood Transfusion, Nagoya City University Medical School, Kawasumi, Mizuho, Nagoya 467-8601, Japan. E-mail: mizokami@med.nagoya-cu.ac.jp Accepted 4 May 2000 Journal of Medical Virology 62:456–462 (2000) © 2000 WILEY-LISS, INC.