Kokosharov, P.

Kuzmov, K.

English

Varna Medical University Press: Journals

~ U Jbbih forC tcI \ti / ь\ Z f fCONCERNING THE SEASON-FACTOR IN PERTUSSIS/ 4 K. Kuzmov, p. Kokosharov4Thp problem of seasonal factors in whooping cough needs further elucida­tion, Tanev andSJiterev (10) establish ajarger widespreading of the affections during the warm months of the year, owning to the increased contact between children. Bratovanoy^ Targov and Yankov (1) point out that the seasonal factor in whooping cough is rejected as a contributing cause by Samet and Londar (cited by Guslitz — 4).Gromashevski (3) attachesjrrrportance to coughing and unorganized, out­door familial contacts (intercourse) between\hildren during the warm sea­sons of the year. Guslitz (4) assumes that the seasonal pertussis curves are similar in different countries, regardless of geographic and climate condi­tions.The discordant opinions motivated the authors to undertake an investi­gation on the problem of the seasonal factor in whooping cough and the probable contributory cause.t Method and materialThe seasonal pertussis morbidity rate is established on a nation-wide ocale and separately for the European-Continental and Continental-Medi­terranean climatic regions as well as according to sex, organized and not organized children, aged up to 6  years; the city of Varna is included in the study, covering the period 1960—1964.The-morbidity rate is determined on the basis of data furnished by re­cording journals of infectious diseases, standard form № 60, Epidemiological Institute — Varna. The remaining data are obtained from the statistical de­partment—District People’s Council, Hydro-metereological Service — Varna and Central Statistical Direction.One hundred epidemiologic investigations are carried out on pertussis patients, aiming anamnestic detection of catarrhal phenomena involving the upper airways during the incubation period i. e. up to ten days after their probable contact with subjects affected with whooping cough.A comparative study is made of the curves of the average number sunny days per month and the seasonal aspects of whooping cough for the city fo Varna, for the period 1960—1964.174 K. Kuemov, Р. Kokosharov 2Fig. 1. The seasonal factors of whooping cough morbidity in Bulgaria, in the Europe­an-Continental and Continental-Mediterranean climatic regions and for the city of Varna, covering the period 1960—1964, expressed in percentiles— . — . — . Bulgaria— X — X — X the  ci ty  of  Varna---------------------- European-Continental c l im atic  region----------------------Continental-Mediterranean climatic  regionDiscussionIt is obvious from diagram I that the seasonal curves on a nationwide scale and for the city of Varna in particular, covering the period 1960— 1964, show a sharp rise beginning from May, reach a peak in July with a steep fall beginning from September. The lowest morbidity is recorded du­ring the period September — April, i. e. during the 8  cooler months of the year, for the period studied, less than one half of the total number of affec-3 Concerning the Season-Factor in Pertussis 175Fig. 2. The seasonal factors of whooping cough among organised and unorganized chil* dren up to 6 years of age in the city of Varna for the period 1960—1964, inpercentiles— . — . — . organized children up to 6 years of age  unorganized children  up to  6 years of age— — — — school-childrentions are registered on a nation-wide scale — 11919, whilst during the four warmer months — 12876. The data obtained for the city of Varna are simi­lar — 647, resp. 927. Comparing the seasonal curves of the two climatic re­gions in the country, it has been established that in addition to the charac­teristic maximum upsurge during July, a minor one is also noted during February for the Continental-Mediterranean region (+). The seasonal sex curves are almost parallel.176 K. Kusmov, Р. Kokosharov 5/ X X X / XII 1 II III IV V VI MU Mill— 6.8 6.2 31 41 5.3 3,5 5.3 5.7 9.2 154 20,2 13.0- r - V m Щ 77.2 11.0 12,8 13.3 4.5 3.4 3.6 15 2.0— 9.5 4.3 1.8 IjS 2.9 2,9 4.3 6.0 6.0 6.7 /3,4 13.8Fig. 3. The seasonal factors in whooping cougli and upper airways’ acute catarrhs compared to the average number sunny days per month in Varna over the period L_ _ 1960—1964 in percentiles---------------- —  whooping cough— — — — — acute catarrhs of the  upper airways— — sunny daysDiagram II demonstrates that the seasonal curves among organized and not organized children, aged up to 6  years inclusive, differ in their ascending arms, with the curve of the latter showing an earlier rise; both seasonal cur­ves are with equal modal values and virtually coincident descending arms. The school-age seasonal curve, that is children aged 7—17 years, is increased sooner, reaching its maximal value in June.How could all these facts be explained? In attempting elucidation of the seasonal aspects of whooping cough, it is imperative to proceed from the characteristic biology of the pertussis bacterium. It is an aerobe (7, 10), biochemically “ inactive” (7, 10), grows slowly on nutrient media [in 2—6 Concerning 'the Season-Factor in Pertussis 1774 days (10), in 3—4 days (2, 5, 7), in 2—5 days (8 )] only provided antibio­tics are added for preventing the inhibitory action of the surrounding mi­croflora (mainly bacteria, as the vira, being intracellular parasites, rould hardly be reporduced in the nutrient media employed). In addition, whooping cough bacteria are propagated on the superficial mucosa of the respiratory tract (9, 10). The latter finding warrants the assumption that whooping cough bacteria could" hardly compete the activied conditioned pathogenic or pathogenic bacterial microflora along the mucosa of the respiratory tract, even in instances of viral etiology of the upper airways’ affections, on account of the circumstance that the viral infectious process is invariably accompanied by catarrhal phenomena of the respiratory tract, brought about by the supplementary action of the conditioned pathogenic bacterial flora. The biologic antagonism pointed out, is in all likelihood, the cause contributing for the widespreading of the whooping cough disease mainly during the warm months of the year, when the mucosa of the respiratory tract is in a state of physiological balance.The comparative study of the seasonal dynamics of upper airways’ acute catarrhs and whooping cough (see diagr. 3) readily outlines their inverse dependence. This practically mirror pattern of the two seasonal curves con­firms the role played by the antagonism between the pertkssis bacteria and the microflora, responsible for the acute catarrhs of the upper respiratory tract.Against the background of 100 epidemiologic investigatipns, performed on patients with whooping cough, it was established, from the past history, that in 78 of the total, catarrhal phenomena within the upper airways were absent for a period ranging from 8  to 1 0  days after the supposed contact with the contagion source, i. e. they were in the incubation period. Owing to the fact that the mucosa of the infected with pertussis bacteria was in a state of physiological balance and the biologic antagonism could not be manifested, the contaminated were affected.Of particular interest for the seasonal factor is likewise the pathogenesis of the disease, respectively of the coughing, as the latter provides for the propagation of the pertussis bacteria at a greater distance, thereby contri­buting for the possibility of contamination, occurring in the open air, during summertime children games.The phase during which the stimuli remain within the surrounding me­dium is furthermore favoured by the water evaporation from the bacteria in higher temperatures of the air and by the production of “nucleoli“, likewise remaining for longer time in the air (10). All this leads to the activation of the mechanism of transmission of the contamination in outdoor condi­tions, especially during the comparatively warm months of the spring; the acute intensification of sun radiation during the summer creates unfavourable conditions for the accomplishment of the phase during which the stimuli remain in the external environment (see diagram 3).Immunization likewise exerts influence upon the seasonal factor. The latter is adequately manifested with a modal value during July concerning the period 1956 — 1959 for the city of Varna. However, following the mass application of anti-pertussis immunization (for the period 1960—1964), a comparatively more uniform distribution of the affection was established except for the strongly pronounced seasonal upsurge in 1962, which was12 Scr ipta scientifica niedica178 K. Kusmov, К. Kokocharov 6the result of a cyclic manifestation. The cause for its occurrence should be sought for in the untimely and incomplete immupe treatment of all indi­viduals liable to immunization (see tible 1 ) and possibly, in the low effec­tiveness of the anti-whooping cough vaccine.Tabl e  1Table 1 illustrates the subjects liable to immunization against whooping cough and immunized quarterly in Varna, covering the period 1963— 1964Year Quarters Liable to immunization Subjected to immuniza­tion1 513 1651962 II 519 603III 524 745IV 552 5991 493 2061963 11III493572417896IV 552 6111964 1 604 250II 555 828InferencesThe seasonal factor in whooping cough might be explained with the cha­racteristic biology of the morbid condition stimulus, its pathogenesis, natu­ral-climatic aspect and concomitant acute catarrhs of the upper respiratory tract, dependent on the intercourse activity of the children and the extent of their immune protection.R E F E R  E N C E S1. Б р а т о в  анов,  Д. ,  Ж- Т а р г о в ,  К. Ян к о в .  Ръководство за практическа ра­бота по епидемиология. Хр. Г. Данов, Пловдив, 1965, 109—111.2. В е р б е в ,  П. Частна епидемиология. Мед. и физк., С., 1957, 289—302.3. Г р о м а ш е в с к и, Л. В. Общая зпидемиология. Медицина. М., 1965, 166—170.4. Г у с л н ц ,  Механизм передачи инфекции. Под ред. Л. В. Г р о м а  ш е в с к о г оМедгиз, М., 1962, 338—351.5. З а  ха рова,  М. С. Коклюш. Рук. по микробиология, клиннке и зпид. инфекц.болезнен, т. VI, Медицина, М., 1964, 350—352.6. К у з м о в ,  К., П. К о к о ш а  ров.  Год. науч. трудове ВМ И —Варна, т V, 1966,св. I, 175—185.This report was presented to the II Scientific Meeting of the Higher Medica- Institute — Varna, held 24 through 26 November, 1966.( +  ) The Continental — Mediterranean climatic region is characterized by com­paratively warm autumns and cooler springs.7 Concerning the Season-Factor in Pertussis 1797. Микробиология важи. инфек. болез. челов. Под ред. Б.Я.  Зльберта, Беларусс,Минск, 1965 , 364—382.8. Пя т к и н ,  К- Д. Микробиология. Медицина, М., 1965, 297—300.9. С к л я р о в а ,  Н. Н. Коклюш. Зпидем. Под ред. Г. Я. З м е е в а .  Медгиз,Ленингр. отдел., 1957, 334—350.10. Т а н е в ,  Ив. ,  П. Ще ре в. Коклюш. Мед. и физк., С. 1960, 9—11, 18,24, 27. О СЕЗОННОСТИ ПРИ КОКЛЮШЕК. Кузмов и П. КокошаровР Е З Ю М ЕИзучена сезонность за период 1960—1964 г. Установлено наличие лет- ней сезонности с модой сезонной кривой в июле месяце. На месяцн V— VIII приходится более половини заболеваний изученного периода.Сезонность объясняется биологическими особенностями коклюшной бактерии, патогенезом заболевания, повишенной активностью общения детей и степенью солнечной радиации.За период 1960—1964 г., из-за массового применения противококлюш- ной иммунизации, в сравнении с периодом 1956—1959 г. устанавливается почти равномерное распределение заболеваний, в течение всего года.Цикличность в периоде 1960—1964 г. сохраняется и она обусловливает моду суммарной сезонной кривой в м. VII для рассматриваемого периода.

CONCERNING THE SEASON-FACTOR IN PERTUSSIS

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CONCERNING THE SEASON-FACTOR IN PERTUSSIS

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