CLINICAL-DIAGNOSTIC VALUE OF BORDETELLA PERTUSSIS GENETIC MARKERS IN CONTACT PERSONS IN FAMILIAL FOCI

Abstract

Goal. Evaluation of duration and frequency of Bordetella pertussis DNA detection in contact persons in family foci of whooping-cough.Materials and methods. 116 persons from 59 family foci of pertussis were examined in contact with sick young children. The DNA of B. pertussis bacteria in nasopharyngeal swabs was detected by real-time PCR (PCR-RV) using a test system developed at Gamaleya Research Institute of Epidemiology and Microbiology (Moscow). The bacterial load and the duration of the release of genomic equivalents (GE) of B. pertussis DNA were determined in dynamics at 1, 3 and 6 months. Results. Among the contact persons in family foci, adults accounted for 59,48%, adolescents and schoolchildren – 10,35% and 12,07% respectively. Cough was absent in 35,34% of contact persons, 20,69% had a rare dry cough, 24,14% had a dry compulsive cough and 19,83% had a typical cough. None of the contact family members were diagnosed with whooping cough, although 64.66% of the patients had clinical signs of the disease, mainly its atypical form (44.83%). Among the carriers of B. pertussis adults accounted for 82.92%, among patients with atypical forms of whooping cough – 51.92%. In the study of nasopharyngeal swabs using the PCR-RV method, it was found that 86.10% of the contact persons detected DNA of B. pertussis. After 3 months in 90% of the contacts, the DNA of pertussis causative agent was detected in a minimum amount of 101-102GE/ml in the sample. After 6 months, B. pertussis was sanitized in 50% of the examined patients. 12.5% of the samples identified avirulent forms of the causative agent of pertussis, formed as a result of movement of IS481 in operon bvgAS.The conclusion. In 86.1% of contact persons in family foci for a long time (from 3 to 6 months), detection of genetic markers of the causative agent of pertussis from the nasopharynx was noted, including 35.34% of those examined in the absence of cough. This, along with the reported genetic mutation in operon bvgAS in 12.5% of cases, can characterize the presence of persistence of B. pertussis, explaining its preservation in circulation in the conditions of mass vaccine prevention.

Keywords

• whooping cough
• contact
• children and adults
• real-time pcr
• persistence