Infant Pertussis and Household Transmission in Korea

Kwon, Hyo Jin; Yum, Sook Kyung; Choi, Ui Yoon; Lee, Soo Young; Kim, Jong Hyun; Kang, Jin Han

Although paroxysmal cough manifested for more than 1 week in all cases, whooping cough was present in only 3 cases (14.3%). There were 4 cases (19.0%) of pneumonic infiltration, 3 cases (14.3%) of hyperinflation on radiologic examinations. Four patients with abnormal chest radiographic finding were not immunized with DTaP vaccination, and remaining 3 patients were received with 1 dose of DTaP vaccination. All patients except 2 cases were examined by multiplex PCR for respiratory virus identification. Two patients had concomitant infections of rhinovirus and respiratory syncytial virus, respectively, and severity was not increased in these patients. Absolute lymphocytosis was noted in 12 patients (57.1%). Of note, absolute lymphocytosis was found more commonly in patients (8/9, 88.9%, average age: 45.8 days) who did not receive DTaP vaccination than patients (4/12, 33.3%, average age: 88.0 days) who did receive DTaP vaccination (P = 0.024, Table 2 ). The mean length of hospital stay among all patients was 11.7 days. However, the mean length of hospitalization for patients without DTaP vaccination was 15.4 ± 6.6 days, which was significantly longer than the 8.8 ± 3.8 days of patients with DTaP vaccination (P = 0.009, Table 2 ). Two patients were admitted to the intensive care unit (ICU); both of them did not receive DTaP vaccination, and one of these patients treated with a mechanical ventilator. There were no deaths due to pertussis during the study period (Table 1) . On the result of diagnostic methods, PCR had the highest sensitivity showing positivity for all 21 cases (100%), however, confirmed cases with culture were 9 (42.9%) which showed the lowest sensitivity. Although RT-PCR and serological test were not performed in all patients, high sensitivity was observed in all patients done with these tests.