CARTAS AL EDITOR
To the editor: Respiratory infections (RI) and acute diarrhoea (AD) are the main causes of morbidity and mortality among Mexican children. A retrospective analysis of rotavirus (RV) epidemics in Merida, Mexico from 2003 to 2008 indicates that 31.5% of children with diarrhoea also present respiratory symptoms. We hypothesized that the co-occurrence (mixed clinical symptoms) of RI and AD may also be a result of mixed diarrheal and respiratory viral infections in children. To address this possibility we evaluated the presence of different respiratory viruses in children diagnosed with acute diarrhoea in two slums with poor housing and health conditions in Merida.
This prospective study involved a total of 127 children under 5 years of age with AD who received medical attention at the "Units of Social Insertion" (USIs) from July 2003 to June 2004. The selected USIs are health units serving people in the city who do not have social security. Faecal samples were collected to detect RV infection and a throat swab was collected from all children to detect influenza and/or other respiratory viruses. Clinical and epidemiological data were collected from all patients. Faecal samples were processed for rotavirus (RV) using polyacrylamide gel electrophoresis (PAGE).1 Throat swabs were processed for respiratory viruses, including influenza A M gene and respiratory syncityal virus (RSV) with nested RT-PCR, as previously described.2
RV was identified in 61 of the samples (48%) included in the study, of which 37 children (61%) showed at least one respiratory symptom. The most commonly referred symptoms were cough and nasal congestion (35% and 34%, respectively), followed by rhinorrea (33%). Respiratory viruses were detected in 9% of samples (10 influenza A, one RSV), including five mixed infections with RV and influenza A. The clinical features of patients positive for influenza were diarrhoea (10/10), fever (5/10), rhinorrea (6/10), nasal congestion (6/10), cough (5/10) and general malaise (5/10). Samples positive for respiratory viruses were detected in July and December 2003 (influenza A), and January-March 2004 (influenza A and RSV), coinciding with seasonal patterns of influenza circulation in Yucatan.3
Our findings suggest that respiratory viruses are present in children presenting mixed diarrheal and respiratory clinical symptoms, sometimes having mixed viral infections, as we have shown. Since other viruses (such as rhinoviruses or metapneumovirus) were not evaluated, the possibility of co-infection cannot be totally ruled out. Nevertheless, the recent influenza A H1N1 epidemic also showed that mixed diarrheal and respiratory clinical symptoms may occur in some cases;4 the accurate diagnosis of respiratory and/or diarrhoeal viruses should be considered.
Declaration of conflicts of interest: The authors declare that they have no conflict of interests.
1. Puerto FI, Polanco-Marin G, González-Losa MR, Zavala JE, Ortega G. Role of rotavirus and enteric adenovirus in acute paediatric diarrhoea at an urban hospital in Mexico. Trans R Soc Trop Med Hyg 1989; 83:396-398.
2. Ayora-Talavera G, Dorantes- Mezquita NE. Human Metapneumovirus in children with influenza-like illness in Yucatan, Mexico. Am J Trop Med Hyg 2007; 76:182-183.
3. Ayora-Talavera G, Góngora-Biachi RA, López-Martínez I, Moguel-Rodríguez W, Pérez-Carrillo H, Vázquez-Zapata V, et al. Detection of human influenza virus in Yucatán, México. Rev Invest Clin 2002; 54:410-414.
4. Charisma D, Endang RS, Matthew RK, Magdarina A, Erlin L, Timothy MU, et al. Influenza virus infection among pediatric patients reporting diarrhea and influenza-like illness. BMC Infectious Diseases 2010; 10:3.
Jesús Gilberto Gómez-Carballo, BSc,
María del Refugio González-Losa, PhD,
Marylin Puerto-Solís, MD,
Luis Manzano-Cabrera, BSc,
Javier Cámara-Mejía, BSc,
Guadalupe Ayora-Talavera, PhD.
Laboratorio de Virología. Centro de Investigaciones Regionales Dr. Hideyo Noguchi. Universidad Autónoma de Yucatán. Mérida, Yucatán, México.