Respiratory syncytial virus associated illness in high-risk children and national characterisation of the circulating virus genotype in South Africa.
BACKGROUND
There is limited information about respiratory syncytial virus (RSV) in high-risk children from developing countries or on the genotype characterisation of the circulating virus.


OBJECTIVE
To define the proportion of children with RSV associated lower respiratory tract infections (LRTI) that had risk factors for severe disease and to genotype the circulating RSV strains across the country.


METHODS
A prospective study was performed in four distinct regions. During April 2000-December 2000 (period 1), all children, with LRTI or without underlying high risk factors for severe RSV disease were enrolled. During January to September 2001 (period 2), only children with LRTI with underlying high risk factors were enrolled. Nasopharyngeal aspirates were evaluated for RSV infection using an ELISA test. RSV isolates were also subtyped and genotyped.


RESULTS
Fifty three (24%) of 220 children enrolled during period 1 had risk factors for severe RSV disease; in addition to which a further 38 high-risk children were enrolled during 2001. RSV was isolated from 16 (30%) of 53 and 37 (22%) of 167 high-risk and non-high risk children, respectively, P=0.31. High-risk children were more likely to require intensive unit care (25 vs. 2.7%, P=0.02) and were also more likely to be hospitalised for a longer duration (median 7 vs. 5 days, P=0.06) than non high-risk infants. Overall (periods 1 and 2), RSV was isolated from 34 (37.4%) of the 91 high-risk infants enrolled. Among high-risk children, those from whom RSV was isolated were more likely to require hospitalisation (73.5 vs. 54.4%, P=0.07) and admission to an intensive care unit (14.7 vs. 1.8%, P=0.03) than those from whom RSV was not isolated. Of 40 isolates subtyped during period one, 92.5% were subtype A. Further, 27 (83.3%) of 30 subtype A isolates genotyped during period 1 clustered with GA2.


CONCLUSIONS
RSV is an important cause of LRTI among high-risk infants in a developing country such as South Africa. For the season in question, the genotype that was dominant in Johannesburg was isolated throughout the country, suggesting that successful genotypes may have the ability to spread nationwide.
Madhi
Shabir A
SA
Paediaric Infectious Diseases Research Unit, Wits Health Consortium, Chris Hani-Baragwanath Hospital, PO Box 1038, SAIMR-Room 11, Bertsham, 2013, South Africa. shabirm@mail.saimr.witx.ac.za
Venter
Marietjie
M
Alexandra
Richard
R
Lewis
Humphrey
H
Kara
Yatish
Y
Karshagen
William F
WF
Greef
Michael
M
Lassen
Cheryl
C
D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017720:Molecular Epidemiology; D010802:Phylogeny; D011446:Prospective Studies; D012367:RNA, Viral / Q000235:genetics; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology*; D012136:Respiratory Syncytial Viruses / Q000235:genetics* / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D012307:Risk Factors; D012621:Seasons; D013019:South Africa / Q000453:epidemiology
D012367:RNA, Viral