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Original Article

Serodiagnosis of Acute Respiratory Infections in Children in Georgia I. C h k h a i d z e , N. M a n j a v i d z e a n d K. N e m s a d z e

I

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 ~ctivity 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 217o (14-24%) of deaths are attributed to p n e u m o n i a alone. 1 More then 200 viral species are a s s o c i a t e d w i t h 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? 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. ~ 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

p r o c e d u r e a s s o c i a t e d w i t h significant m o r b i d i t y ; 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 r e p o r t of the e x p e r i e n c e of the investigation of the etiological agents for the ARI in hospitalized children u n d e r 15 who were studied for infection with viruses and atypical pathogens. MATERIALS AND METHODS

Correspondence and Reprint requests : Dr. L Chkhaidze, 33, Vaja

Pshavela Av., Department of Pediatrics, Tbilisi State Medical Universi~, 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 u p p e r and l o w e r r e s p i r a t o r y tract i n f e c t i o n s 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 I 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 a n d p u l m o n a r y i n f i l t r a t e s on CXR. We excluded children with nosocomial LRTI and those, who were immunocompromised. Acute u p p e r a n d / o r lower respiratory tract infections were defined as an illness with the following signs a n d s y m p t o m s : history of cough, tachypnea, strydor, fever, chest retraction, m o a n i n g , perioral cyanosis, wheezing, and rales. Acute obstructive laryngitis (croup), nasopharyngitis and pharyngitis were c o n s i d e r e d as u p p e r r e s p i r a t o r y tract infections; p n e u m o n i a , bronchitis a n d w h e e z i n g bronchitis as a lower respiratory tract infections. Clinical diagnosis of p n e u m o n i a was m a d e b y p h y s i c a l e x a m i n a t i o n a n d confirmed by chest x-ray and pulse-oximetry. Data w a s r e c o r d e d a n d m a n a g e d on excel s p r e a d sheet. The SPSS 11.0 computer software for windows was used for statistical analyses. 808 children, w h o 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, i n c l u d i n g details of all r e s p i r a t o r y symptoms were taken. The following investigations were performed within 24 hours of admission: full b l o o d count, blood chemistry tests, chest x - r a y a n d p u l s e - o x i m e t r y . A c u t e a n d convalescent serum samples were tested b y ELISA for IgM and IgG antibodies to RSV, adenovirus, influenza A and B, parainfluenza 1-3 virus and cytomegalovirus. Acute infection was d i a g n o s e d 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 p r e v i o u s l y described criteria? The presence of Chlamydiatrachomatis, Chlamydia pneumoniae, Mycoplasma pneumoniae a n d Legionella pneumophilla w e r e d e f i n e d b y a significant antibody response - for Mycoplasma pneumoniae specific IgM _>1:100, or a 4-fold increase in IgG titer in p a i r e d serum simples; for chlamydiae: specific IgA __.1:16, or a 4fold increase in I g G titer. 4 Reagents: h n m u n o L I S A , Orgenics (Israel); ABL ( G e r m a n y ) d e t e c t e d on the Hiperion MRIII (USA) and Labsystem Multiskan M C C / 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 w e r e 496 m a l e s 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 f r o m 1 to 3 a n d 45 in age more than 3 years). On the contrary, the rate of the mixed-infections i n c r e a s e d in a c c o r d a n c e w i t h the age (18, 21, 35 consequently). TABLE1. 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 s h o w n in Fig. 1. It is clear, t h a t the i n c i d e n c e 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 I to 3 years. 100%

--

80,% 6O% 40% 20% 0%

|nt|usnza

P 3rainfluenza

Adenov|rus

RSV

JE3 0-6 rno~s I~ 6- ] 2 m orqths [] 1-3 yeats [] rn ore th~N 3 ysars ]

Fig. 1. Association of viral agents with age of patients At least one pathogen was identified in 468 cases, so the overall detection rate w a s 57.9%. The features of serodiagnoses of these patients are shown in Table 2. The number of virus-positive patients was 301 (37.2%). A m o n g them more frequently detected were: parainfluenza 102 (12.6%), adenovirus 91 (11.2%), influenza A 59 (7.3%), RSV49 (6%). In 93 (11.5%) p a t i e n t s w e r e i d e n t i f i e d a t y p i c a l p a t h o g e n s , a m o n g t h e m Mycoplasma pneumoniae 44 (5.4%), Chlamydia trachomatis 29 (3.5%), Chlamydia pneumoniae 18 (2.2%), and Legionella2 (0.2%). In 74 (9.2%) p a t i e n t s w e r e e s t a b l i s h e d m i x e d infections, a m o n g them in 64 (7.9%) patients viral-viral and in 10 (1.2%) viral-atypical infections. As for o t h e r p a t h o g e n s , it is n o t e w o r t h y the comparatively high rate of detection of CMVinfection (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 TABLE2. Frequency of Single and Paired Sera Evaluation in Children with Acute Respiratory Infections Agent

Criteria

Subj ects n

Viruses

Parainfluenza Adenovirus

Influenza A RSV

Single sample (IgM liter) Paired sample (IgG liter) 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 liter) Single sample (IgA titer) Paired sample (IgG titer) Single sample (IgA liter) Paired sample (IgG titer)

6 38 12 17 2 16

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, l o w e r one at the e n d of a u t u m n (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

Atypical pathogens

Mycoplasma pneumoniae Chlamydia trachomatis Chlamydia pneumoniae

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 s h o w n in Fig. 2. In our study p n e u m o n i a was associated m o s t f r e q u e n t l y w i t h v i r u s e s ( m o s t l y adenovirus) and mixed-infections; wheezing bronchitis was caused by viruses (adenovirus and RSV) and atypical p a t h o g e n s ; b r o n c h i t i s was c o n n e c t e d w i t h v i r u s e s (parc~nfluenza and adenovirus).

60%

:

~

48%

"" :

~

~

''

~ .......

~

20% 0%

~ P n~umonia

Wheez ing bronchitis

I N V m J s El ,aCy'plc, al p a l a o g e n

- - - -

Bronchitis

N Mlxed4rtectlon]

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 m a n i f e s t e d as an encephalitis. As for u p p e r 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 b e g i n n i n g of w i n t e r (December) with clearly expressed peak in last 2 months of w i n t e r (January-February) and is minimal d u r i n g 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

808 children of the age up to 15 years, hospitalised for the treatment of acute u p p e r and lower respiratory tract infections, were studied prospectively to evaluate the etiology and clinical outcomes of the disease. There are few r e p o r t s from d e v e l o p i n g countries concerning the etiological agents in the form of viral and atypical organisms in the same cohort of patients) It is also important, that the subjects of these studies are either specific age groups or parts of the respiratory system: u p p e r 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 ~2%6 to 94%) This rate d e p e n d s on m a n y factors, such as p r o c e d u r a l and l a b o r a t o r y differences, s e v e r i t y of disease, k i n d of investigated materials, number of presumed pathogens, the stage of illnesses, etc. The rate of d e t e c t i o n of pathogens in our study is almost the same as in m a n y other papers/, 8,9 The most of viral pathogens were detected in the age up to 3 years, as it had been reported earlier in m a n y papers.B, 10 In the overwhelming majority of studies the most frequently detected pathogen in children with ARI is RSV.~I, 12,13In 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, 14adenovirus 15 and influenza. BThis unexpected low rate of R S V in our study can be explained by the age of the patients: most papers investigated children under I 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 c o m m o n 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, is' 19 In our 571

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I. Chkhaidze, K. Nemsadze and N. Manjavidze opinion the possibility of adenoviral encephalitis should be t a k e n i n t o c o n s i d e r a t i o n in c a s e of e n c e p h a l i t i s i n children. The higher number of mixed-infections was e s t a b l i s h e d in c h i l d r e n m o r e t h a n 3 y e a r s of age. The r e a s o n m i g h t be h i g h e r p o s s i b i l i t y of contact w i t h o t h e r c h i l d r e n in d a y - c a r e c e n t r e s a n d o t h e r facilities. As for a t y p i c a l p a t h o g e n s , it w a s i n t e r e s t i n g , t h a t t h e rate of these agents w a s h i g h e r in patients u n d e r I y e a r a n d over 3 y e a r s of a g e . T h e m a i n a g e n t i n i n f a n t s w a s C. trachomatis t h a t c a u s e d m a i n l y the A f e b r i l e P n e u m o n i a Syndrome. In older age g r o u p the m a i n atypical p a t h o g e n w a s M.pneumoniae. In the w h o l e , M.pneomoniae w a s the m o s t frequent agent a m o n g atypical pathogens, f o l l o w e d b y C. trachomatis a n d C.pneumoniae. The s a m e correlation w a s s h o w n in o t h e r p a p e r s , 4, 7 t h o u g h in one r e p o r t w a s established the p r e v a l e n c e of C.pneumoniae} ~ In o u r s t u d y the rate of detection of parainfluenza a n d R S V d e c r e a s e d a c c o r d i n g to the age, the rate of influenza w a s h i g h e r in c h i l d r e n o v e r I y e a r a n d the l o w e s t in the a g e g r o u p u p to 6 m o n t h s . A d e n o v i r u s o c c u r r e d p r e d o m i n a n t l y in the age f r o m 1 to 3 year. The rates of detection of the viral agents v a r y in the literature, b u t t h e y u n d e r l i n e t h e i m p o r t a n c e of a g e in v i r a l A R I J 3, x4 O u r r e p o r t also d e s c r i b e d the seasonal variations of the m a i n r e s p i r a t o r y tract p a t h o g e n s . It h a d b e e n s h o w n in m a n y r e p o r t s that s e a s o n a l d i s t r i b u t i o n s of r e s p i r a t o r y agents depends on the country's geographical location and climate conditions. The climate in G e o r g i a is s u b t r o p i c a l t e m p e r a t e , so o u r d a t a are a l m o s t similar to p a p e r s f r o m c o u n t r i e s w i t h t h e s a m e w e a t h e r c o n d i t i o n s , 6 b u t is different f r o m the r e p o r t s of the countries w i t h hotter or colder climates, a3,17 I n c o n c l u s i o n , v i r a l a g e n t s a r e t h e m a i n c a u s e s of a d m i s s i o n in G e o r g i a n c h i l d r e n w i t h u p p e r a n d l o w e r r e s p i r a t o r y tract infections. A better u n d e r s t a n d i n g of the e t i o l o g y of a c u t e r e s p i r a t o r y i n f e c t i o n s in all off t h e regions of the w o r l d m a y be helpful for t i m e l y decision of specific t h e r a p y , both, a n t i v i r a l a n d antibacterial, w h i c h can h e l p p e d i a t r i c i a n s to e s t i m a t e a n d m a n a g e c h i l d r e n w i t h 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.

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Indian Journal of Pediatrics, Volume 73--July, 2006