Human Bocavirus in Patients with Encephalitis, Sri Lanka, 2009–2010

Daisuke Mori, Udaya Ranawaka, Kentaro Yamada, Shaman Rajindrajith, Kazushi Miya, Harsha Kumara Kithsiri Perera, Takashi Matsumoto, Malka Dassanayake, Marcelo Takahiro Mitui, Hisashi Mori, Akira Nishizono, Maria Söderlund-Venermo, and Kamruddin Ahmed

Author affiliations: Oita University, Yufu, Japan (D. Mori, K. Yamada, T. Matsumoto, M.T. Mitui, A. Nishizono, K. Ahmed); University of Kelaniya, Ragama, Sri Lanka (U. Ranawaka, S. Rajindrajith, H.K.K. Perera); Colombo North Teaching Hospital, Ragama (M. Dassanayake); University of Toyama, Toyama, Japan (K. Miya, H. Mori); University of Helsinki, Helsinki Finland (M. Söderlund-Venermo)

Abstract

We identified human bocavirus (HBoV) DNA by PCR in cerebrospinal fluid from adults and children with encephalitis in Sri Lanka. HBoV types 1, 2, and 3 were identified among these cases. Phylogenetic analysis of HBoV1 strain sequences found no subclustering with strains previously identified among encephalitis cases in Bangladesh.

Encephalitis is a serious infection causing high rates of illness and, in industrialized countries, has a case-fatality rate of 6.5%–12% (1,2). However, the situation in developing countries is largely unknown. Globally, the causes remain unrecognized in 60%–85% of encephalitis cases (1,2). Recently, human bocavirus (HBoV) has been implicated in causing life-threatening encephalitis in Bangladeshi children (3). In Sri Lanka, information about the causative agents of encephalitis is scarce. The aim of this study was to determine the occurrence of HBoV and other possible pathogens in children and adults with encephalitis admitted to a tertiary care hospital in Sri Lanka.

The Study

The study was conducted at Colombo North Teaching Hospital, Ragama, Sri Lanka, during July 2009–November 2010. A total of 233 patients (110 adolescents/adults > 12 years of age and 123 children) were enrolled. Adolescents and adults were admitted to adult wards. Cerebrospinal fluid (CSF) samples were available from 191 patients. Criteria for enrolment were as follows: any combination of the triad of fever, headache, and vomiting, along with altered level of consciousness, seizures, focal neurologic deficits, altered behavior, and signs of meningeal irritation. Clinical and laboratory information was available for 164 patients. The male:female ratio for adolescents/adults was 1.3:1; ages ranged from 12 to 90 years (mean 42 years); For children, the male:female ratio was 0.7:1; ages ranged from 2 to 144 months (mean 48 months). The ethics committees of the University of Kelaniya and Oita University approved this study.
CSF samples were subjected to macroscopic examination, total and differential leukocyte counts, bacterial culture, Gram staining, and measurement of protein and glucose. Blood was cultured for bacteria and examined for total and differential leukocyte counts, erythrocyte sedimentation rates, and hemoglobin and C-reactive protein levels.
Classical encephalitis-causing pathogens (Table) and diarrheagenic viruses, such as HBoV, rotavirus, astrovirus, norovirus, parechovirus, and human adenovirus (HAdV), were determined in CSF by PCR (Technical Appendix

[PDF - 64 KB - 2 pages]) (3–5). Anti-n-methyl-D-aspartate receptor (NMDAR) encephalitis was diagnosed by on-cell Western analysis (6). For HBoV PCR-positive patients, HBoV types 1–4-specific IgG and IgM responses in CSF samples were measured by enzyme immunoassays (7).