Bordetella pertussis Strains, China | CDC EID

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Volume 16, Number 11–November 2010
Research
Effect of Vaccination on Bordetella pertussis Strains, China

Liu Zhang,1 Yinghua Xu,1 Jianhong Zhao, Teemu Kallonen, Shenghui Cui, Yunqiang Xu, Qiming Hou, Fengxiang Li, Junzhi Wang, Qiushui He, and Shumin Zhang Comments to Author
Author affiliations: National Institute for the Control of Pharmaceutical and Biological Products, Beijing, People's Republic of China (L. Zhang, Y. Xu, S. Cui, Q. Hou, F. Li, J. Wang, S. Zhang); Hebei Medical University, Shijiazhuang, PRC (J. Zhao); The Second Hospital of Shijiazhuang City, Shijiazhuang (Y. Xu); National Institute for Health and Welfare, Turku, Finland (T. Kallonen, Q. He); and University of Turku, Turku (T. Kallonen)

Suggested citation for this article

Abstract
Whole-cell pertussis vaccine was introduced in China in the early 1960s. We used standard typing methods to compare 96 Bordetella pertussis isolates collected before and after introduction of vaccination, during 1953–2005. The following vaccine-type alleles of the pertussis toxin (ptx) gene were characteristic for all prevaccination strains: ptxA2, ptxA3, and ptxA4. The shift to ptxA1 occurred since 1963. All isolates collected since 1983 contained ptxA1. Pertactin (prn) allele 1, prn1, was predominant, although prn2 and prn3 have been detected since 2000. Serotypes fimbriae (Fim) 2 and Fim2,3 were found in all isolates collected before 1986. During 1997–2005, Fim3 became prevalent. Although changes in electrophoresis profiles over time were observed, the predominant profiles during 1997–2005 resembled those during the prevaccine era and those found in Europe before the 1990s. B. pertussis strains in China may differ from those in countries that have a long history of high vaccine coverage.

Whooping cough (pertussis) is an acute respiratory infectious disease caused by the bacterium Bordetella pertussis. After the whole-cell pertussis (Pw) vaccines were introduced in many countries during 1940–1960, illness and death rates from pertussis have decreased dramatically (1,2). However, pertussis remains a leading cause of vaccine-preventable deaths worldwide (1). A resurgence of pertussis has been observed in developed countries despite high vaccination coverage (3–9).

In the People's Republic of China, vaccination against pertussis was started in the early 1960s, when 3 doses of Pw vaccine combined with diphtheria and tetanus toxoids were given at 3, 4, and 5 months of age. In 1982, a booster dose at 18 months of age was added (10,11). Pw vaccines are free of charge in China. Since 1995, acellular pertussis (Pa) vaccines containing purified pertussis toxin (Ptx) and filamentous hemagglutinin have been also introduced. However, because Pa vaccines are offered at the patient's expense, use of these vaccines has been minimal, especially in some resource-limited areas. Although since 2007 Pa vaccines have been included in the national expanded program on immunization, Pa and Pw vaccines are still used in most provinces because of limited availability and cost of Pa vaccines. Although the reported vaccination coverage for the primary 3 doses increased with time, before the 1980s it was low. From 1983 through 2008, coverage ranged from 58% to 99% (median 93%) (Figure 1) (12).

In China, pertussis is a reportable infectious disease, and the number of reported cases has been decreasing (Figure 1). Since the 1990s, incidence has been <1 case/100,000 population (12). In China, pertussis is clinically diagnosed by physicians; laboratory methods such as culture, PCR, and serologic analysis are not used for diagnosis of pertussis. Therefore, the reported low incidence may be related to the diagnostic criteria used, suggesting substantial underreporting. Pertussis remains endemic to China (10–12), and a local outbreak was reported in April 1997. In many countries, divergence in major antigens Ptx, pertactin (Prn), fimbriae (Fim) 2, Fim3, and tracheal colonization factor (TcfA) between the vaccine strains and circulating isolates has been reported (3,4,7,9,13–16). Furthermore, marked changes in B. pertussis strains have been found in these countries after introduction of vaccination. To learn more about the B. pertussis strains circulating in China, we used standardized typing methods to analyze and compare B. pertussis isolates collected before and after the introduction of vaccination (17). full-text: Bordetella pertussis Strains, China | CDC EID

Suggested Citation for this Article

Zhang L, Xu Y, Zhao J, Kallonen T, Cui S, Xu Y, et al. Effect of vaccination on Bordetella pertussis strains, China. Emerg Infect Dis [serial on the Internet]. 2010 Nov [date cited]. http://www.cdc.gov/EID/content/16/11/1695.htm

DOI: 10.3201/eid1611.100401

1These authors contributed equally to this article.