Respiratory syncytial virus genotypes circulating in urban Ghana: february to november 2006

Abstract

Introduction: Respiratory syncytial virus (RSV) is the major cause of acute lower respiratory tract  infection (ALRI) in young children. RSV strains have been divided into 2 major antigenic groups (A and B), which are further divided into several genotypes, but very little is known about its circulating genotypes in Ghana. This study characterized RSV genotypes detected in children with ALRI in Accra between  February and November 2006.

Methods: Nasopharyngeal aspirates (NPA) were obtained from children diagnosed with ALRI between  February and November 2006. The NPA were screened for RSV using a nested multiplex reverse  transcriptase polymerase chain reaction (RT-PCR) method for genotyping RSV. Viral RNA was extracted from the NPA using guanidinium isothiocyanate method and purified with an RNAID commercial kit.  Care-givers gave their consent prior to specimen collection. Administered questionnaires captured  information on patient demographic and clinical history.

Results: A total of 53 children were enrolled in the study with a male to female ratio of 3:1. Of the 53 NPA  analyzed, 60.4% (32/53) were positive for RSV. Subsequent genotypic analysis showed that 72% (23/32) of the 60.4% RSV infections were RSV B only and 28% (9/32) were co-infections of both RSV A and B. Children between the ages of 2 - 12 months were the most affected age group per an RSV infection rate of 37.5% (12/32). No significant difference was detected in the recovery rate of ALRI (98.1%) and RSV (96.9%) positive patients from the infection. One patient died resulting in a mortality rate of 3.1%. Bronchopneumonia (20 out of 32 cases) was the major diagnosis on admission. RSV infection was  seasonal dependent, described by 2 peaks in October and April-May.

Conclusion: Both RSV A and RSV B genotypes co-circulated during the study period with RSV B  predominating. RSV may possibly be the main pathogen of lower respiratory tract illness during  epidemics in the wet seasons. Genotyping by the multiplex RT-PCR is one of the first attempts at  molecular diagnosis of RSV infection in Ghana.

Key words: Respiratory syncytial viruses, lower respiratory tract infections, multiplex RT-PCR