[The host-opportunistic protozoa system. The incidence of mixed infections (Pneumocystis and cytomegalovirus) in children living in radionuclide-contaminated areas].

The purpose of our study was to determine the influence of ionized radiation onto the frequency of mixed infections (P. carinii and Cytomegalovirus) in children inhabitants of the settlements affected with radionuclide after Chernobyl accident. Two groups of children were under survey. 1) 103 inhabitants of Novozybkov (Bryansk Province, Russia) and 38 patients under observation in Moscow paediatric hospital from another affected villages (5-15 Ci/km2) were examined serologically by the diagnostic system "Pneumo-test" and "Cytomegatest" (Nyarmedic, Moscow, Russia). Cut-off titers for P. carinii were IgM-1: 200, IgG-1: 20, for CMV IgG-1: 200, 2) Retrospective study of 563 patients with respiratory pathology and 1809 died children after acute pneumonia during 14 years period. Sputum and mucus of the patients taken by laryngoscopy and bronchoscopy were studied for P. carinii by microscopy, the section of lungs--histologically. The sediments of urine and saliva were examined for CMV by microscopy and section of different organs_-histologically. Examinations were performed by one and the same highly qualified pathologist. The results of the study were as follows. 1. Of 563 children examined for both P. carinii and CMV 186 (33%) were positive for P. carinii and 189 (33.7%) for CMV. Both pathogens were found in 46 children (8.2%), mainly among 1-2 and 6-12 month age (8.5 and 14.5%, respectively). Retrospective analysis of 1809 autopsy results shows, that in 73 cases (4%) were found only P. carinii, in 200 (11.1%) only CMV and in 24 (1.3%) two pathogens simultaneously. 2. Of 103 children surveyed serologically P. carinii monoinfection was found in 7 (8.8%), CMV-in 25 (24.3%) and coinfection in 55 (53.4%). Estimated frequency for coinfection (if combination of two infections were to be accidental) should equal 46.8%. In control group consisted of 30 children from clean Moscow region the rate of coinfection was 16.7% and estimated rate 15% (the difference between empiric and estimated rates are statistically significant, t > 4). Thus it is clear that the rate of coinfection of P. carinii and CMV is always high either in clean or in affected by ionized radiation regions. This rate determined by microscopy was higher in patients (8.2%) than in autopsy cases (1.3%) and much higher in children from affected region (53.3%) than in control (16.7%), being determined serologically. Separate interest present geometric mean titers found in the cases of coinfection. The titer for anti-CMV IgG in children from affected regions was rather high (5884 vs. 1246 in control) and on the contrary titers for anti-P. carinii IgM and IgG were lower than in control (512 vs. 1245 and 58 vs. 159 respectively). We are incline to interpret the results of our study as evidence of increased susceptibility to P. carinii and CMV in those children whose immune system was suppressed by premorbid factors or ionized radiation and peculiar symbiotic relationships of P. carinii and CMV resulting in enhancement of their infectiousness.