RESUMO
Objective:To evaluate the auxiliary diagnosis value of bacterial culture, polymerase chain reaction (PCR) and serum anti-pertussis toxin immunoglobulin G (AntiPT-IgG) level detection in suspected pertussis.Methods:A total of 110 suspected cases of pertussis treated in the Department of Pediatrics of Wuhu No.1 People′s Hospital from June 2018 to May 2019 were recruited for the study.The nasopharyngeal swabs of all cases were collected for Bordetella pertussis culture and specific nucleic acid PCR detection.Serum samples of 78 cases were collected for the detection of AntiPT-IgG level by enzyme linked immunosorbent assays.Results:The positive rates of bacterial culture group and PCR group were 21.8% and 30.0%, respectively, with no statistically significant difference ( χ2=1.198, P>0.05). The culture positive rate of cases with the duration of cough<2 weeks was 32.1%, which was signi-ficantly higher than that of cases with the duration of cough about 2-4 weeks (14.3%) or >4 weeks (9.1%) ( χ2=6.522, P<0.05). The PCR positive rate of cases with the duration of cough <2 weeks was 39.6%, which was also significantly higher than that of cases with the duration of cough about 2-4 weeks (25.7%) or > 4 weeks (13.6%) ( χ2=6.126, P<0.05). The mean value for serum AntiPT-IgG level of 78 cases was (75.727±78.454) IU/mL, the median AntiPT-IgG levels of cases with the duration of cough<2 weeks and about 2-4 weeks were 5.909 IU/mL and 20.948 IU/mL, respectively, and the positive rates were 14.7% and 38.1%, respectively.The AntiPT-IgG level of cases with the duration of cough> 4 weeks and that at convalescent stage were (79.281±68.254) IU/mL and (107.242±75.750) IU/mL, and the positive rates were 39.1% and 57.1%, respectively. Conclusions:In the vaccine era, the results of pathogenic and serological tests should be combined to assist the clinical diagnosis of pertussis.The positive rate of bacterial culture and specific nucleic acid pathogen detection in children with cough duration less than 2 weeks is high, and the serological diagnosis is more effective after the duration of cough is over 4 weeks.
RESUMO
There are a variety of factors contributing to pertussis resurgence, which is related to short duration of immunity provided by the vaccine, the difference of vaccination strategies, the change of epidemiological characteristics, antibiotic resistance, the variation of bordetella pertussis, the improvement of diagnostic criteria and the advancement of the monitoring system.There has been a decrease in the number of cases of natural infection since the vaccination, leading to a change in the prevalence of pertussis currently.The decline in population group immunity causes a decrease of serum antibody titer transmitted from the mother to the newborn.As a result, unvaccinated infants have poor immunity against pertussis in the early stage, and infants under 1 year old are prone to severe pertussis.Children and adolescents are also susceptible to pertussis owing to the short-term efficacy of the vaccine.They often present with chronic cough after infection.Adults infected with pertussis are unheeded because of atypical symptoms or occult infection, and they would infect young babies.To improve the diagnosis and treatment of pertussis, it is necessary to meliorate the laboratory diagnosis, study bacterial variation and drug resistance, strengthen disease surveillance, seek more optimized immunization strategies and develop new vaccines.In this paper, the causes of pertussis resurgence were reviewed, in order to provide reference for prevention and control of pertussis in China.