Журнал «Здоровье ребенка» 3 (46) 2013

Introduction. Pertussis is an infectious acute respiratory disease that affects people of all age groups, however, young children are likely to experience the more severe clinical course and extremely frequent complications. Although according to official statistical data of WHO the annual morbidity remains within the limits of several thousands cases worldwide, real morbidity is much higher. Pertussis affects 30-50 million people every year, 90% of them live in developing countries. In Ukraine, despite the fact that 85-90% of children are vaccinated against pertussis annually, infants pertussis is still characterized by high morbidity rates.

Methods, design, participants. The retrospective analysis of the inpatient medical records of children aged 0 – 12 mo. at Lviv Regional Infectious Diseases Hospital has been performed. The data of 33 patients who were undergoing treatment during 2012 y. and 26 children who were under medical care in 1997-2001 y.y. have been analyzed. Since positive results of bacteriological investigation have been obtained only in several cases the selection criteria has included children who had cough lasting for at least 14 days, accompanied by paroxysmal coughs, inspiratory whoop, vomiting after coughing, cyanosis, apnea, without another reason, and also according to modern diagnostic algorithm [2] (appendix 1). One more criterion for our selection was increase in the absolute lymphocytes amount (>9,500×10⁹/l), due to according to modern data, lymphocytosis in a child suspected with pertussis is highs sensitive and is highs specific diagnostic criterion (specificity - 75%, sensitivity – 89%) [3]. The clinical course of infant’s pertussis severity has been estimated according to 0-20 point M.-P. Preziosi and E. Halloran scale [4]. The final analysis has been performed on the basis of 104 variants including epidemiologic data, clinical data, and results of laboratory investigations. The statistical analysis has been made with the use of MS Excel, Statistica 8.

Results, discussion. Dividing children according to the months of hospitalization revealed that despite the fact of year-round hospitalizations with pertussis was observed, the statistically significant increases in morbidity have been noticed twice during years: in January - March and in July - September. Two waves of increase in pertussis morbidity were detected in winter-spring and summer-autumn periods in 2012 y. as well as ten years ago (figure 1).

Children of two groups have not been significant different according to the age at the time of hospitalization, birth weight, child’s weight at the beginning of inpatient treatment and sex. Statistically differences between the onset of first symptoms of pertussis (rhinitis, coughing, fever) and the time of hospitalization have not been found. However, the duration of cough before the admission in children hospitalized with pertussis in 2012 y. was significant longer – 15,17±2,3 days (in comparison with 13,25±3,7 days in 1997-2001 y.y., p<0,05), as well as the duration of spasmodic cough which lasted 6,80±3,33 days (in comparison with 4,69±1,18 days, p <0,05).

In 2012 y. the inpatient treatment of children lasted for 13,57±2,72 days, while average duration of the course of the disease from the beginning of catarrh and the end spasmodic stages was 27,21±5,51 days. The duration of these periods has not considerably changed (table 1). The duration of the disease and inpatient treatment according to statistics have not been significant connected with the age of the child, clinical course severity, complication rate or results of laboratory and instrumental examinations.

Young infants had longer duration of the disease compare with children aged 6-12 months, but these were not statistically differences. In 2012 y., average duration of pertussis from the early catarrh stage till the end of spasmodic cough period was 28,18±2,31 days in infants aged 0-6 months and 25,27±2,88 days in children aged 7-12 mo. Similar peculiarities have been detected in children hospitalized with pertussis in 1997 – 2001y.y. Respectively, average duration of the above-mentioned periods was 30,12±4,20 and 26,81±3,05 days.

Among those hospitalized in 2012 y., 2 children (6%) were vaccinated once or twice and 6 infants (23,7%) were vaccinated among those undergoing treatment in 1997-2001 y.y. The onset of pertussis occurred once or twice in vaccinated infants as well as in the cases of the onset of the disease in a short time following last vaccination (on the average 10,23±3,10 days).

Generally, pertussis in young children of both groups had typical clinical course. At the time of hospitalization fever was detected in 42,3% of patients, but all children with hyperthermia had subfebrile temperature (mean temperature was 37,2±0,16°C in children hospitalized in 2012 y. and 37,6±0,34°C in children treated in 1997-2001y.y.). Duration of hyperthermia did not exceed 3,5 days and lasted on the average 1,56±0,14 days. Higher temperature has been detected in children aged 7-12 mo., in comparison with children aged 0-6 months that has been also approved by the results of correlative analysis – r=0,25, p<0,05 (correlation between the children’s age and temperature).

Almost all patients had tachypnea (90,9% - 92,3%), but more expressed breathlessness was observed in children hospitalized in 1997-2001 y.y. (average respiratory rate was 42,8±12,9 per min.), in comparison with children undergoing treatment in 2012 y. (mean respiratory rate – 36,6±8,9 per min.). Children undergoing treatment in different year periods have not been characterized by significant differences in frequency of inspiratory whoop, apnea, vomiting after coughing, duration of apnea, duration of coughing with inspiratory whoop. Rales (moist, small-bubbling) have been detected in 66,7% of children undergoing treatment in 2012 y. and in 96,3% of those hospitalized in 1997-2001 y.y. (p<0,05) Rales lasted significant longer time in the second group – on the average 6,6±1,42 days (p<0,05) (table 2,3).

The severity of pertussis has been determined according to M.-P. Preziosi, E. Halloran scale [4], at the admission in both groups pertussis severity scores was not different. It has been evaluated in 9,39±2,95 points and 8,81±2,60 points, respectively. The worsening of patient’s condition at the inpatient department, mainly related with increased frequency of typical paroxysms with/ without whoops, appearance of face swelling, episodes of apnea, conjunctival injection, bronchitis or bronchopneumonia development of the was the common for both groups. On the 5^th day of inpatient treatment the pertussis severity was estimated in 11,21±2,92 points and 11,12±2,74 points. According to the CBC results, leukocytosis has been observed in 31 children (93,9%) hospitalized in 2012 y. Hyperleukocytosis (the amount of leukocytes exceeded 30,000x10⁹/l) has been observed in 3 children (91%) and the average level of peripheral blood leukocytes was 20,9±4.87x10⁹/l (table 4).

In the period during 1997-2001 y.y., 25 children (95,1%) had leukocytosis, 5 infants (19,3%) - hyperleukocytosis, but mean leukocyte count in this sub-group was significant higher – 24,20±3,90x10⁹/l (in comparison with 14,00±2,85x10⁹/l in 1997-2001 y.y. (p<0,05). It should be mentioned that hypochromic anemia was more frequent in children undergoing treatment in 1997-2001 y.y., the significant lower level of hemoglobin was detected in these children (96,83±17,52 g/l (p<0,05).

At the course of the disease result of repeated blood analysis (on the average made in interval in 7,5 days) showed that in most patients leucocytes and lymphocytes absolute amount was intensively decreasing (except for the difference of lymphocytes counts in children hospitalized in 1997-2001 y.y). These differences have been statistically significant (p<0,05) (table 5).

Conclusions. Thus, according retrospective medical records analysis of children aged 1-12 months, hospitalized with pertussis, with the interval of 10 years it has been established that pertussis-related morbidity of children of young age is increasing, distinct connection of the disease onset with the season has been found. Longer disease duration the at the pre-hospital stage, less severe breathlessness, less frequency and less duration of changes in lungs and lower leucocytes levels in peripheral blood have been attributed to the differences in the clinical course of pertussis in infants in 2012 y. in comparison with 1997-2001 y.y. We have distinguished some reasons, which obviously caused these and other differences in the clinical course of pertussis in children of young age. Firstly – it is change of the dominating cerotype B. pertussis agent for the other one. According to T.A. Romanenko, I.P. Kolesnikova data [1], several facts of changes in serotype have been established during the last decades, namely: in 1993 y. there was a change of dominating serotype from 1.2.3 to 1.0.3, in 2003-2004 y.y. – from 1.0.3 to 1.0.0, in 1999-2000 y.y. – from 1.2.3 to 1.0.3, 2003-2004 y.y. – from 1.0.3 to 1.2.3, and in 2004-2005 y.y. – from 1.2.3 to 1.0.3. Secondly – the other type of vaccines for regularly vaccination used. Thus, in Ukraine acellular vaccine has been registered and used since 2004 y. which has replaced whole cell vaccine. Thirdly – it is introduction of modern treatment regimens with using other antibiotics – modern erythromycin drugs, new non-opioid antitussive medications on the basis of butamirate citrate (Sinecod).