Seroprevalence of pertussis in China

Abstract

Pertussis remains an important cause of infant death worldwide and is an ongoing public health concern even in countries with high vaccination coverage. A cross-sectional seroepidemiological study was undertaken to estimate true incidence rates and gain further insight into the epidemiology and burden of pertussis in China. During 2011, a total of 1080 blood samples were obtained from healthy individuals between 0 and 86 y of age in Zhengzhou, Central China. Serum IgG antibodies against pertussis toxin (PT) and filamentous hemagglutinin (FHA) were measured quantitatively using ELISA. The results showed that the geometric mean titers of PT and FHA IgG were 6.48 IU/mL (95% CI: 5.70-7.41 IU/mL) and 11.39 IU/mL (95% CI: 10.22-12.87 IU/mL) among subjects less than 4 y of age, indicating that pertussis antibody levels were low despite high vaccination coverage. Of the 850 subjects≥4 y of age, 56 (6.6%) had anti-PT IgG titers above 30 IU/mL, and 11 (1.3%) had antibodies titers above 80 IU/mL. The estimated age-specific incidence of infection with B. pertussis revealed a peak incidence in the 31 to 40 y age group, followed by the 41 to 60 y age group. Taken together, these results indicate that pertussis is common in Chinese subjects in Zhengzhou, especially in adults, suggesting that the disease burden is underestimated in China. Therefore, our study stresses the importance of strengthening the diagnostic capacity and improving surveillance system for delineating current epidemiological profiles of pertussis. Most importantly, it may be advisable to re-evaluate the current Chinese pertussis immunization schedule and implement to booster doses for older children, adolescents and adults.

Brief Report: Seroprevalence of Pertussis Infection in HIV-Infected Adults in the United States

“…We found that 4.3% of subjects not vaccinated with Tdap in the last 6 months had serologic evidence of recent pertussis infection, and that the annual pertussis infection rate among subjects not vaccinated in the last 5 years was 10.5–17.5%. This rate is 1000-fold higher than the annual incidence of reported cases for the general U.S. population in 2014 20 , consistent with other seroprevalence studies that have found pertussis to be vastly underreported 15,18,19 . It is also 10-fold higher than the seroprevalence rate reported from a study among healthy American adolescents and adults in 1997–1999 4 .…”

“…Similarly, an Israeli seroprevalence study of subjects at least three years of age demonstrated peak incidence rates in subjects >60 years old, despite this age group having the lowest incidence of reported pertussis cases 21 . Further, a Chinese seroprevalence study in subjects 4–86 years old revealed peak incidence of pertussis in the 31–40 followed by the 41–60 year old age groups 18 . Studies among U.S. adult and adolescent subjects with cough illness suggest 13–15% of these illnesses can be attributed to pertussis 22,23 .…”

“…Several studies have shown that mean anti-PT IgG levels drop to 9–14 units/ml by 18–36 months after Tdap vaccination 13,16,17 . In addition, other studies have used anti-PT IgG levels ≥30 units/ml to diagnose recent pertussis infections in subjects not vaccinated against pertussis for ≥2.5 years 18,19 .…”

Seroprevalence of Bordetella pertussis antibodies in adults in Hungary: results of an epidemiological cross-sectional study

“…However, others have reported highest seropositivity rates in various younger adult age groups [21, 24] or little variation by age among adults [25]. Similarly, some previous studies have reported a possible link between likely pertussis infection and advancing age [20, 22, 31], but others have reported no such link [25, 34, 35]. Whether these results are indicative of true differences between countries and/or years or whether they are due to a lack of sufficient power to detect such differences is unclear.…”

“…Higher male seropositivity has also been reported in studies from Mexico ( p  = .0007) [24] and Korea ( p  = .023) [23]; but studies from Spain [26], Greece [21], and The Gambia [22] have reported no significant differences in seropositivity between genders. Regarding higher male likelihood of recent infection, this has been reported to be significant in a study from The Netherlands [31], non-significant in a study from Denmark [34], higher but significance not reported in one from The Gambia [22], or no significant gender differences in two studies from China [35, 36]. Overall, it is unclear whether there is a true link between pertussis and gender and, if there is, the cause is unknown.…”