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Original Article
Serodiagnosis of Acute Respiratory Infections in Children in Georgia I. Chkhaidze, N. Manjavidze and K. Nemsadze 1 Tbilisi State Medical University, Department of Pediatrics, 1Michael Guramishvili Pediatric Clinic, Tbilisi, Georgia
ABSTRACT Objective. To investigate the etiology of acute respiratory infections in hospitalized children. Methods. A total of 808 children were studied. Investigation of RSV, Adenovirus, Parainfluenza, Influenza A and B, C.trachomatis, C.pneumoniae, M. pneumonia and Legionella were performed with an ELISA for IgM, IgG and IgA antibodies detection. Results. There were 496 males and 312 females giving a male: female ratio of 1.6:1. Ages range from 1 month to 15 years. The overall detection rate was 57.9%. The most frequently detected were: parainfluenza 12.6%, adenovirus 11.2%, influenza A 7.3%, RSV 6%, M. pneumoniae 5.4%, C.trachomatis 3.5% and mixed-infections 9.2%. Pneumonia was associated most frequently with adenovirus and mixed-infections; wheezing bronchitis - with adenovirus, RSV and M. pneumoniae; bronchitis - with parainfluenza and adenovirus, diseases of upper respiratory tract - with parainfluenza and adenovirus. Peak of the virus activity was during winter (influenza, parainfluenza, adenovirus, RSV) and autumn (parainfluenza, RSV). Conclusion. Viruses are the main causes of ARI in Georgian children. A better understanding of the etiology of ARI in all of the regions of the world may be helpful for timely decision of specific therapy, which can help pediatricians to estimate and manage children with ARI. [Indian J Pediatr 2006; 73 (7) : 569-572] E-mail:
[email protected]
Key words : Acute respiratory infections; Eetiology, Children.
Acute respiratory infections are the leading cause of mortality and morbidity in children. More than 10 million children die each year and in the developing countries 21% (14-24%) of deaths are attributed to pneumonia alone.1 More then 200 viral species are associated with respiratory tract disease in humans and this number is increasing almost each year.2 The etiology of ARI varies according to countries’ economic conditions as well as their geo-regional locations.3 Determination of the ARI etiology is a challenge, because the diagnostic tests of respiratory samples that are non-invasively obtained are insufficiently sensitive to identify the causative agent. 4 In most cases of ARI it is often difficult to identify the infective etiology. The various diagnostic techniques used for identification of the etiologic agents: blood culture, lung puncture, nasopharyngeal aspirates, serological tests, immuno-assays, PCR. Lung puncture is an invasive
procedure associated with significant morbidity; nasopharyngeal aspirates can be used for detection of viruses, but the possibility of concomitant bacterial lower respiratory tract infection (LRTI) cannot be ruled out with confidence; the PCR are costly, still experimental and not available for routine use. Most of the studies from developing countries for the identification of the etiological agents for ARI were directed towards one pathogen either bacteria, viruses or atypical organisms, in either upper or lower respiratory tract. There is paucity of papers that studied all of the etiological agents in patients with the ARI of both, upper and lower respiratory tracts. Below is our report of the experience of the investigation of the etiological agents for the ARI in hospitalized children under 15 who were studied for infection with viruses and atypical pathogens. MATERIALS AND METHODS
Correspondence and Reprint requests : Dr. I. Chkhaidze, 33, Vaja Pshavela Av., Department of Pediatrics, Tbilisi State Medical University, 0177, Tbilisi, Georgia, Fax: (995-32) 940009.
Indian Journal of Pediatrics, Volume 73—July, 2006
A prospective trial was designed to evaluate the etiology of upper and lower respiratory tract infections in hospitalized children. The study protocol was approved 569
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I. Chkhaidze, K. Nemsadze and N. Manjavidze by Ethics Committee of M.Guramishvili Pediatric Clinic. The study was explained to the parents and they signed the informed consent form. The inclusion criteria were: age from 1 month to 15 years; community acquired upper or/and lower RTI; presence of cough with/without fever which lasted for less than 2 weeks; tachypnea or chest retraction and pulmonary infiltrates on CXR. We excluded children with nosocomial LRTI and those, who were immunocompromised. Acute upper and/or lower respiratory tract infections were defined as an illness with the following signs and symptoms: history of cough, tachypnea, strydor, fever, chest retraction, moaning, perioral cyanosis, wheezing, and rales. Acute obstructive laryngitis (croup), nasopharyngitis and pharyngitis were considered as upper respiratory tract infections; pneumonia, bronchitis and wheezing bronchitis as a lower respiratory tract infections. Clinical diagnosis of pneumonia was made by physical examination and confirmed by chest x-ray and pulse-oximetry. Data was recorded and managed on excel spread sheet. The SPSS 11.0 computer software for windows was used for statistical analyses. 808 children, who were admitted at M.Guramishvili Paediatric Clinic from the period 1997-2003, were enrolled in the study. At the first study visit, a full history was taken from the parents. A full clinical examination was performed for all children, and birth weight, feeding history, full medical history, including details of all respiratory symptoms were taken. The following investigations were performed within 24 hours of admission: full blood count, blood chemistry tests, chest x-ray and pulse-oximetry. Acute and convalescent serum samples were tested by ELISA for IgM and IgG antibodies to RSV, adenovirus, influenza A and B, parainfluenza 1-3 virus and cytomegalovirus. Acute infection was diagnosed if the child had a significant antibody response to one of the viruses in blood sera (an IgM-specific antibody titre ≥1:100 or a fourfold increase in IgG antibody in paired sera), according to previously described criteria.5 The presence of Chlamydia trachomatis, Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophilla were defined by a significant antibody response - for Mycoplasma pneumoniae specific IgM ≥1:100, or a 4-fold increase in IgG titer in paired serum simples; for chlamydiae: specific IgA ≥1:16, or a 4 fold increase in IgG titer. 4 Reagents: ImmunoLISA, Orgenics (Israel); ABL (Germany) detected on the Hiperion MRIII (USA) and Labsystem Multiskan MCC/ 340 (Finland). A positive infection was defined either in a single test or in paired sera taken 2-3 weeks apart. RESULTS A total of 808 children fulfilling the inclusion criteria were investigated. There were 496 males and 312 females giving a male: female ratio of 1.6:1. Ages range from 1 570
month to 15 years, with the majority of patients (18.5%) being in the 1-3 years age group. The rate of the ARI in the first six months was almost the same in comparison with the second six months of life. The age distribution of respiratory tract infections is shown on a Table 1. It is seen that the rate of respiratory viruses decreased in older age groups (142 in age up to 1 year, 114 in age from 1 to 3 and 45 in age more than 3 years). On the contrary, the rate of the mixed-infections increased in accordance with the age (18, 21, 35 consequently). TABLE 1. Main Infective Agents According to Age Infective agents 0-6 month Virus Atypical path. Mixed-infection Total
62 14 12 87
Age of patients 6-12 1-3 month year 80 11 6 97
114 15 21 150
More than 3 year 45 53 36 134
The age distribution of the ARI caused by viral agents is shown in Fig. 1. It is clear, that the incidence of parainfluenza and RSV decreased according to the age, the rate of influenza is lowest in the age group up to 6 months, and adenovirus is occurring predominantly in the age from 1 to 3 years.
Fig. 1. Association of viral agents with age of patients
At least one pathogen was identified in 468 cases, so the overall detection rate was 57.9%. The features of serodiagnoses of these patients are shown in Table 2. The number of virus-positive patients was 301 (37.2%). Among them more frequently detected were: parainfluenza 102 (12.6%), adenovirus 91 (11.2%), influenza A 59 (7.3%), RSV 49 (6%). In 93 (11.5%) patients were identified atypical pathogens, among them Mycoplasma pneumoniae 44 (5.4%), Chlamydia trachomatis 29 (3.5%), Chlamydia pneumoniae 18 (2.2%), and Legionella 2 (0.2%). In 74 (9.2%) patients were established mixedinfections, among them in 64 (7.9%) patients viral-viral and in 10 (1.2%) viral-atypical infections. As for other pathogens, it is noteworthy the comparatively high rate of detection of CMV infection (10 cases, 1.2%). Indian Journal of Pediatrics, Volume 73—July, 2006
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Serodiagnosis of Acute Respiratory Infections in Children in Georgia TABLE 2. Frequency of Single and Paired Sera Evaluation in Children with Acute Respiratory Infections Agent
Criteria
Viruses Parainfluenza Adenovirus Influenza A RSV Atypical pathogens Mycoplasma pneumoniae Chlamydia trachomatis Chlamydia pneumoniae
Subjects n
Single sample (IgM titer) Paired sample (IgG titer) Single sample (IgM titer) Paired sample (IgG titer) Single sample (IgM titer) Paired sample (IgG titer) Single sample (IgM titer) Paired sample (IgG titer)
81 21 44 47 52 7 35 14
Single sample (IgM titer) Paired sample (IgG titer) Single sample (IgA titer) Paired sample (IgG titer) Single sample (IgA titer) Paired sample (IgG titer)
6 38 12 17 2 16
Association of pathogens and clinical syndromes. The distribution of the main groups of pathogens in children with different respiratory syndromes of lower respiratory tract is shown in Fig. 2. In our study pneumonia was associated most frequently with viruses (mostly adenovirus) and mixed-infections; wheezing bronchitis was caused by viruses (adenovirus and RSV) and atypical pathogens; bronchitis was connected with viruses (parainfluenza and adenovirus).
Fig. 2. Distribution of main pathogens of LRTI
It is interesting to note that in two cases adenovirus caused severe ARI with the involvement of the central nervous system that was clinically manifested as an encephalitis. As for upper respiratory tract infection, croup in 78.8% cases was caused by parainfluenza virus. Other diseases of upper respiratory tract (nasopharyngitis and pharyngitis) were caused by parainfluenza (17.7%) and adenovirus (6.1%). Seasonal patterns. In Georgia the four seasons are generally recognised as spring (from March to May), summer (from June to August), autumn (from September to November) and winter (from December to February). The results show that the frequency of the cases caused by influenza virus increases in the beginning of winter (December) with clearly expressed peak in last 2 months of winter (January-February) and is minimal during summer and early autumn. parainfluenza infection was characterized by 2 peaks: the first, more expressed at the Indian Journal of Pediatrics, Volume 73—July, 2006
end of autumn and the beginning of winter (November, December, January) and the second, less expressed at the beginning of spring (March, April). Seasonal rhythms of adenovirus infection also has 2 peaks: the first one, more expressed, was observed in spring (March, April) and the second, lower one at the end of autumn (October, November). The assessment of seasonal rhythms of RSV infection emphasized elevation of frequency in autumn and winter with highly expressed peak in November. DISCUSSION 808 children of the age up to 15 years, hospitalised for the treatment of acute upper and lower respiratory tract infections, were studied prospectively to evaluate the etiology and clinical outcomes of the disease. There are few reports from developing countries concerning the etiological agents in the form of viral and atypical organisms in the same cohort of patients.3 It is also important, that the subjects of these studies are either specific age groups or parts of the respiratory system: upper or lower. We have investigated the etiology of upper and lower respiratory tract infections in the wide range of age groups of children with a focus on possible pathogens: viruses and atypical agents. Specific etiological agents were established in 57.9% cases. The rate of identification of etiological agents in children with ARI varies from 22%6 to 94%. 3 This rate depends on many factors, such as procedural and laboratory differences, severity of disease, kind of investigated materials, number of presumed pathogens, the stage of illnesses, etc. The rate of detection of pathogens in our study is almost the same as in many other papers.7, 8, 9 The most of viral pathogens were detected in the age up to 3 years, as it had been reported earlier in many papers.6, 10 In the overwhelming majority of studies the most frequently detected pathogen in children with ARI is RSV.11, 12, 13 In our study, RSV was the predominant viral pathogen only in children aged from 6 to 12 months. More frequent causes of ARI in the whole group of patients were parainfluenza, adenovirus and influenza A. There are few reports which didn’t show the predominance of the RSV: with the prevalence of parainfluenza,14 adenovirus15 and influenza.6 This unexpected low rate of RSV in our study can be explained by the age of the patients: most papers investigated children under 1 or 3 years (in which the rate of RSV is the highest); in our study we examined older children as well. Besides, the geo-regional features of respiratory pathogens should be taken into account. Our result showed that the adenovirus was the second most common viral pathogen, followed by influenza A virus. Similar prevalence was found in other studies,16, 17 though the most frequently detected pathogens in these papers were RSV. As for adenoviral encephalitis, the same finding was shown in other reports as well, 18, 19 In our 571
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I. Chkhaidze, K. Nemsadze and N. Manjavidze opinion the possibility of adenoviral encephalitis should be taken into consideration in case of encephalitis in children. The higher number of mixed-infections was established in children more than 3 years of age. The reason might be higher possibility of contact with other children in day-care centres and other facilities. As for atypical pathogens, it was interesting, that the rate of these agents was higher in patients under 1 year and over 3 years of age. The main agent in infants was C. trachomatis that caused mainly the Afebrile Pneumonia Syndrome. In older age group the main atypical pathogen was M.pneumoniae. In the whole, M.pneomoniae was the most frequent agent among atypical pathogens, followed by C. trachomatis and C.pneumoniae. The same correlation was shown in other papers,4, 7 though in one report was established the prevalence of C.pneumoniae.20 In our study the rate of detection of parainfluenza and RSV decreased according to the age, the rate of influenza was higher in children over 1 year and the lowest in the age group up to 6 months. Adenovirus occurred predominantly in the age from 1 to 3 year. The rates of detection of the viral agents vary in the literature, but they underline the importance of age in viral ARI.13, 14 Our report also described the seasonal variations of the main respiratory tract pathogens. It had been shown in many reports that seasonal distributions of respiratory agents depends on the country's geographical location and climate conditions. The climate in Georgia is subtropical, temperate, so our data are almost similar to papers from countries with the same weather conditions, 6 but is different from the reports of the countries with hotter or colder climates.13, 17 In conclusion, viral agents are the main causes of admission in Georgian children with upper and lower respiratory tract infections. A better understanding of the etiology of acute respiratory infections in all off the regions of the world may be helpful for timely decision of specific therapy, both, antiviral and antibacterial, which can help pediatricians to estimate and manage children with ARI. Acknowledgements We would like to thank the patients and their physicians for their participation in this study. We also acknowledge the excellent technical assistance provided by Prof. N. Sikharulidze.
REFERENCES 1. Black RE, Morris SS, Bryce J. Where and why are 10 million children dying every year? Lancet 2003; 361: 2226-2234.
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2. Mackie PL. The classification of viruses infecting the respiratory tract. Pediatr Respir Rev 2003; 4: 84-90. 3. Kabra SK, Lodha R, Broor S et al. Etiology of acute respiratory tract infection. Indian J Pediatr 2003; 70: 33-36. 4. Principi N, Esposito S, Blasi F, Allegra L. Role of Mycoplasma pneumoniae and Chlamydia pneumoniae in children with community acquired lower respiratory tract infections. Clin Inf Dis 2001; 32 : 1281-1289. 5. Heiskanen-Kosma T, Korppi M, Jokinen C et al. Etiology of childhood pneumonia: serologic results of a prospective, population-based study. Pediatr Infect Dis J 1998; 17 : 986-991 6. Ahn KM, Chung SH, Chung EH, Koh YJ et al. Clinical characteristics of acute viral lower respiratory tract infections in hospitalized children in Seoul, 1996-1998. J Korean Sci 1999; 14: 405-411. 7. Yin CC, Huah LW, Lin JT et al. Lower respiratory tract infection in hospitalized children. Respirology 2003; 8: 83-89. 8. Tecu C, Gherghina I, Constantinescu C et al. Viral etiology of acute respiratory infections in infants and young children. Roum Arch Microbiol Immunol 1996; 55: 333-339. 9. Torzillo P, Dixon J, Manning K et al. Etiology of acute respiratory tract infection in Central Australian Aboriginal children. Pediatr Infect Dis 1999; 18: 714-721. 10. Weigl JA, Puppe W, Grondahl B et al. Epidemiological investigation of nine respiratory pathogens in hospitalized children in Germany using multiplex reserve-transcriptase polymerase chain reaction. Eur J Clin Microbiol Infect Dis 2000; 19 : 336-343. 11. Zamberi S, Zulkifli I, Ilina I. Respiratory viruses detected in hospitalized pediatric patients with respiratory infections. Med J Malaysia 2003; 58 : 681-687. 12. Ekalaksananan T, Pientong C, Kongyingyoes B et al. Etiology of acute respiratory tract infection in children at Srinagarind Hospital, Khon Kaen, Thailand. Southeast Asian J Trop Med Public Health 2001; 32: 513-519. 13. Sonoda S, Gotoh Y, Bann F, Nakayama N. Acute lower respiratory infections in hospitalized children over a 6 year period in Tokyo. Pediatr Int 1999; 41 : 519-524. 14. Tumova B, Heinz F, Syrucek L et al. Occurrence and etiology of acute respiratory diseases: result of long-term surveillance programme. Acta Virol 1989; 33: 50-62. 15. Huang JJ, Huang MY, Dai ZK et al. Study on the children of Kaohsiung with acute viral infection of lower respiratory tract by direct immunofluorescent assay. Gaoxiong Yi Xue Ke Xue Za Zhi 1994; 10: 486-491. 16. Savy V, Baumeister E, Bori F et al. Etiological and clinical evaluation of respiratory infections in children. Medicina (B Aires) 1996; 56 : 213-217. 17. Starliotto SM, Siqueira MM, Muller RL et al. Viral etiology of ARI among children in Porto Alegre, RS, Brazil. Rev Soc Bras Med Trop 2002; 35: 283-291. 18. Chuang YY, Chui CH, Wong KS et al. Severe adenovirus infection in children. J Microbiol Immunol Infect 2003; 36: 37-40. 19. Sakata H, Taketazu G, Nagaya K. Outbreak of severe infection due to adenovirus type 7 in a paediatric ward in Japan. J Hosp Infect 1998; 39: 207-211. 20. Kayfusuz S, Koksai I, Aydin K et al. Investigation of Atypical bacteria and virus antigens in respiratory tract infections by use of an immunofluorescence method. Jpn J Infect Dis 2004; 57: 33-36.
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