Viral Agents in Children Presenting with Signs and Symptoms of Respiratory Infections in the Ashanti-Akyem North District of Ghana
Respiratory Infections (RIs) constitute one of the major causes of morbidity and mortality among the pediatric population of developing countries. When caused by viruses, their manifestations are very difficult to detect on clinical grounds and most importantly by conventional diagnostic methods. Whilst studies on the viral causes of RIs are well documented in developed countries, there exist scanty information on them in most developing countries. The main aim of this study was to optimize and establish molecular diagnostic systems which are able to simultaneously detect several pathogens per clinical sample for respiratory viral infections. The viral aetiology and determinants of respiratory viral infections in children were also evaluated. Three real time multiplex Polymerase Chain Reaction (m-RT-PCR) and five monoplex real-time polymerase chain reactions (RT-PCR) were optimized and established for the detection of twelve respiratory agents during the study. The three m-RT-PCRs included two duplexes for the simultaneous detection of respiratory syncytial virus and human metapneumovirus (RSV/hMPV), influenza A and B (influenza A/B) and a triplex for parainfluenza 1, 2 and 3 (PIV 1-3). The five monoplexes included three assays for Rhinoviruses (RhV), Enteroviruses (ENT), Adenoviruses (AdV) and two for non-viral agents Mycoplasma pneumoniae (MYC) and Chlamydophilia pneumoniae (CHL). Nasopharyngeal swabs were taken from children who presented with at least two signs and symptoms suggestive of respiratory infection to the out patient department of Agogo Presbyterian Hospital in the Asante Akim North district in the Ashanti Region of Ghana between February 2008 and March 2009. Also collected were their sociodemographic, socioeconomic and clinical data. A predictive algorithm for the viral causes of respiratory infection was then developed. A total of 1,191 children were enrolled in the study. The developed assays detected 476 pathogens in 429 (36.5%) children. RSV/hMPV was the most frequently detected pathogen in 154 (13.1%), RhV in 93 (7.9%), PIV 1-3 in 83 (7.1%) and influenza A/B in 68 (5.8%) of the children. Furthermore, AdV and ENT were detected in 40 (3.4%) and 29 (2.4%) respectively whilst MYC was found in 6 (0.5%) of the children. CHL was detected in only 1 (0.1%) child. More than one respiratory agent was detected in 47 (3.9%) of the study participants. Despite the differences in the symptoms presented, most viral agents could not be associated with specific clinical signs or symptoms. The risk for RVIs decreased steadily with increasing age (OR=0.57, 95% CI: 0.49-0.67, p<0.05) with the youngest children (up to 12 months) at highest risk (OR=0.87, 95% CI: 0.69-1.10). This was true for RSV/hMPV, PIV 1-3 and AdV (p<0.05). For influenza A/B, there was an increased risk with increasing age (p<0.05). With an overall male-to-female ratio of 1.2:1, gender (p=0.99), religion (p=0.89) and ethnicity (p=0.56) were not associated with RVIs. High temperature (37.6°C) was also a significant determinant for viral respiratory infections (p<0.05). With the exception of maternal age (p=0.02) and nutrition (p<0.05), none of the maternal factors studied turned out to be predictors of RVIs in the children. Similarly, apart from associations between accessibility to health facilities (p<0.05), none of the socioeconomic factors were determinants of RVIs. While RSV/hMPV and influenza viruses were detectable during the rainfall seasons, PIV, RhV, ENT and AdV were detected sporadically throughout the year. This study has defined the epidemiology of specific respiratory viruses and the clinical presentation of children with signs and symptoms of respiratory infection. With the advent of molecular diagnostic techniques such as multiplex RT-PCR, this study provides valuable information to clinicians and virologists confronted with children suffering from respiratory tract illnesses of viral etiology for possible understanding of the viral causes of these infections.
A Thesis submitted to the Department of Clinical Microbiology, Kwame Nkrumah University of Science and Technology, Kumasi,in partial fulfillment of the requirements for the degree of Doctor of Philosophy, August-2011