T
here are
numerous studies looking at the etiology of bronchiolitis in the West but
few from the tropics(1-4), with only one study from India(5).
We conducted this trial in a Delhi hospital between
January 1 and December 31, 2007 and enrolled 245 infants (1 month to 1
year) with evidence of bronchiolitis (characterized by tachypnea;
respiratory rate more than 60 per minute between 1-2 months of age and
more than 50 per minute beyond 2 months age; with wheezing or fine
crackles) following a written informed consent from parents.
Nasopharyngeal aspirates, nasopharyngeal swabs and throat swabs were
obtained from them and evaluated at the National Institute of Communicable
Diseases (NICD), Delhi. Specimens were processed for viral culture, ELISA
and PCR. The study was approved by the hospital research committee.
Viral identification rate was 46.12%. Respiratory
syncytial virus (RSV) was isolated in 72 (29.38%) cases, adenovirus in 19
(7.75%), influenza virus in 3 (1.22%) (Type A: 1 and Type B: 2),
parainfluenza virus in 9 (3.67 %) (type 1: 7 cases and type 3 : 2 cases),
rhinovirus in 6 (5.31%) and metapneumo-virus in 1 (0.88%). Mixed
infections were documented in 6.6% of cases.
RSV was most commonly isolated in November. The
incidence peaked in the early part of winter, similar to the pattern seen
in the West.
We tried to correlate the clinical profile of cases
with the virus isolated. We found fever, fever with crepitation, and fever
with crepitation and rhonchi, significantly more associated with RSV
compared to infants without RSV (P value 0.015, 0.024 and 0.016,
respectively). Unlike(6), El Radhi, et al. we did not find an
association of fever with more severe illness.
Although a higher severity of illness and fatality
rates in bronchiolitis with adenovirus(7) and rhinovirus(8) have been
reported previously, we found no statistical association between the virus
identified and severity of illness (defined as a Downe’s respiratory
distress score of 4 or more, for purposes of this study).
Antiviral treatment with ribavirin is not prescribed in
the West, except in the most serious cases. In the present study, RSV was
not isolated in 70% cases and its isolation was not associated with more
severe disease. This argues against routine use of ribavirin in
bronchiolitis. More studies need to be done from other parts of the
country to look for regional differences in incidence and etiology.
References
1. Weber MW, Mulholland EK, Greenwood BM.
Respiratory syncytial virus infection in tropical and developing
countries.Trop Med Int Health 1998; 3: 268-280.
2. Weber MW, Dackour R, Usen S, et al. The
clinical spectrum of respiratory syncytial virus disease in The Gambia.
Pediatr Infect Dis J 1998; 17: 224-230.
3. Loscertales MP, Roca A, Ventura PJ, et al.
Epidemiology and clinical presentation of respiratory syncytial virus
infection in a rural area of southern Mozambique. Pediatr Infect Dis J
2002; 21: 148-155.
4. Doraisingham S, Ling AE. Patterns of viral
respiratory tract infections in Singapore. Ann Acad Med Singapore 1986;
15: 9-14.
5. Cherian T, Simoes EA, Steinhoff MC, Chitra K, John
M, Raghupathy P, et al. Bronchiolitis in tropical South India. Am J
Dis Child 1990; 144: 1026-1030.
6. El Radhi AS, Barry W, Patel S. Association of fever
and severe clinical course in bronchiolitis. Arch Dis Child 1999; 81:
231-234.
7. Straliotto SM, Siqueira MM, Machado V, Maia TMR.
Respiratory viruses in the paediatric intensive care unit: Prevalence and
clinical aspects. Mem Inst Oswaldo Cruz 2004; 99: 883-887.
8. Papadopoulous NG, Moustaki M, Tsolia M, Bossios A,
Astra E, Prezerakou A, et al. Association of rhinovirus infection
with increased disease severity in acute bronchiolitis. Am J Respir Crit
Care Med 2002; 165: 1285-1289.