Seroprevalence of antibodies for pertussis and diphtheria among people leaving or entering China: a cross-sectional study.

INTRODUCTION: Despite high population immunity, pertussis remains one of the leading causes of vaccine-preventable deaths worldwide. The aim of this study was to determine the seroprevalence of IgG antibodies to pertussis toxin (PT) and diphtheria among the adult male population leaving or entering China. METHODOLOGY: Blood samples were obtained from 240 Chinese and 207 African healthy adults that were leaving and entering China, respectively. Serum IgG antibodies against PT (anti-PT IgG) and diphtheria were determined. RESULTS: The mean concentration of anti-PT IgG antibodies was 13.82 IU/mL and 18.11 IU/mL for the leaving and entering populations, respectively. None of the studied Chinese leaving China were seropositive for pertussis. Of the 240 subjects leaving China, 209 (87.1%) had anti-diphtheria antibody concentrations of ≥ 0.1 IU/mL and 31 (12.9%) had antibody concentrations between 0.01 and 0.099 IU/mL. Eleven (5.31%) of the studied Africans entering China had anti-PT IgG antibodies higher than 30 IU/mL and thus were considered seropositive for pertussis. Of the 207 Africans entering China, antibody concentrations of ≥ 0.1 IU/mL were found in 164 subjects (79.2%) while 43 (20.8%) had antibody concentrations between 0.01 and 0.099 IU/mL. CONCLUSIONS: Almost all Chinese adult men leaving China and most African men entering China have very low serum antibody levels of pertussis. Furthermore, the antibody level of diphtheria among these two populations was low among adults. A larger population study is needed to determine whether booster vaccinations against pertussis and diphtheria should be considered for adults in China and also for Africans entering China.

Molecular epidemiology of Bordetella pertussis in Greece, 2010-2015.

PURPOSE: To determine the predominant strains of Bordetella pertussis in Greece during 2010-2015. METHODOLOGY: Infants and children (n=1150) (15 days to 14 years) of Greek, Roma and immigrant origin with different vaccination statuses were hospitalized in Athens, Greece with suspected pertussis infection. IS481/IS1001 real-time PCR confirmed Bordetella spp./B. pertussis infection in 300 samples. A subset of samples (n=153) were analysed by multi-locus variable number tandem repeat analysis (MLVA) and (n=25) by sequence-based typing of the toxin promotor region (ptxP) on DNA extracted from clinical specimens.Results/Key findings. A complete MLVA profile was determined in 66 out of 153 samples; the B. pertussis MLVA type 27 (n=55) was the dominant genotype and all tested samples (n=25) expressed the ptxP3 genotype. The vaccine coverage in the Greek population was 90 %; however, the study population expressed complete coverage in 2 out of 264 infants (0-11 months) and in 20 out of 36 children (1-14 years). Roma and immigrant minorities represent 7 % of the Greek population, but make up 50 % of the study population, indicating a low vaccine coverage among these groups. CONCLUSIONS: The B. pertussis MT27 and ptxP3 genotype is dominant in Greek, Roma and immigrant infants and children hospitalized in Greece. Thus, the predominant MLVA genotype in Greece is similar to other countries using acellular vaccines.

Risk Markers for Pertussis Among Infants <4 Months of Age: Understanding the Hispanic Disparity.

OBJECTIVES: Hispanic infants are at greater risk of pertussis compared with other racial/ethnic groups. Studies have shown that the source of Bordetella pertussis infection for most infants is household members. Using a case-control study, we examined risk markers for pertussis among Hispanic and non-Hispanic infants and evaluated whether maternal parity, a proxy for household size, contributes to the ethnic disparity. METHODS: We evaluated infants born in California during 2013-2014; cases were infants reported to California Department of Public Health with pertussis occurring before 4 months of age, and controls were infants who survived to at least 4 months of age without pertussis. Bivariate comparisons and multivariate logistic regression models were used to identify risk markers for pertussis in Hispanic and non-Hispanic infants. RESULTS: Increased maternal parity was associated with greater risk of pertussis, with a clear dose response observed with increasing risk for additional prior births. Teenage mothers were more likely to have infants with pertussis. These were both independent risk factors across all racial/ethnic groups, even when adjusting for important covariates. Preterm birth and Medicaid insurance were also identified as independent risk markers among Hispanic infants only. CONCLUSIONS: Infants of all races/ethnicities with older siblings or born to younger mothers are at increased risk of pertussis. Among Hispanic infants, prematurity and Medicaid insurance were independent risk markers for pertussis. These factors highlight the need to ensure prompt immunization of pregnant women with Tdap at the earliest opportunity starting at 27 weeks gestation.

Antenatal influenza and pertussis vaccine uptake among Aboriginal mothers in Western Australia.

BACKGROUND: Antenatal influenza and pertussis vaccination prevent serious disease in mothers and infants. Aboriginal individuals are at increased risk of infection yet little is known about vaccine coverage among Aboriginal mothers. AIMS: To estimate the uptake of influenza and pertussis vaccination among pregnant Aboriginal women in Western Australia and identify barriers and enablers to vaccination. MATERIALS AND METHODS: Four hundred Aboriginal women, aged ≥18 years, who gave birth to a live infant between April and October 2015, were randomly selected and invited to participate in telephone interviews. Of the 387 women who did not decline, 178 had a functioning phone number and 100 completed the survey. Analyses were weighted by maternal residence. RESULTS: During pregnancy the majority of Aboriginal mothers were recommended influenza (66%; unweighted, 65/96 = 68%) and pertussis (65%; unweighted, 62/94 = 66%) vaccines, with 62% (unweighted, 56/94 = 56%) and 63% (unweighted, 60/93 = 65%) receiving the vaccinations, respectively. Almost all vaccinated women (98%) reported wanting to protect their baby as the reason for immunisation. Rural mothers were more likely than metropolitan mothers to have been vaccinated against influenza (odds ratio (OR) 4.1, 95% CI 1.7-10.2) and pertussis (OR 3.1, 95% CI 1.2-7.6). Recommendation by a healthcare provider was strongly associated with vaccine uptake (influenza: OR 15.6, 95% CI 4.9-49.5; pertussis: OR 13.3, 95% CI 4.6-38.0). CONCLUSION: Vaccination uptake among Western Australian Aboriginal mothers is comparable with rates reported for non-Aboriginal populations worldwide. Provider recommendation is the single most important factor associated with vaccination uptake, underlining the importance of integrating vaccination into routine antenatal care.

Investigation of Pertussis Cases in a Texas County, 2008-2012.

OBJECTIVES: Within the past 25 years, there has been a dramatic increase in the incidence of pertussis cases in the United States. As such, this investigation reports on the high-risk groups and describes risk factors of pertussis cases in a large Texas county. METHODS: This study was a cross-sectional analysis of data collected by health department employees using the Texas Department of State Health Service's Pertussis Case Track Record, which is the standard investigation form for collecting vital information on pertussis cases. We extracted and analyzed county-level data for a 5-year period (2008-2012). The study population at risk included all current residents in this county, and cases included all who were clinically diagnosed as having confirmed or probable pertussis cases that were reported to the health department according to the Centers for Disease Control and Prevention case definition. The vaccination status of a case was defined as fully vaccinated, partially vaccinated, or not vaccinated. RESULTS: A total of 198 probable and confirmed pertussis cases were included in this analysis. Most of the cases were infants younger than 1 year old (n = 107). The largest category of cases was not vaccinated and of the rest, 32.8% were partially vaccinated, 17.2% had unknown vaccination status, and 13.1% were fully vaccinated. Only 48 (24.2%) sources of exposure were identified and they included fathers (14.6%), sisters (14.6%), brothers (14.6%), other children (14.6%), and mothers (12.5%). Many sources of exposure (n = 26, 54.1%) were unaware of their vaccination history. Hispanics accounted for 84.5% of cases in the younger than 1 year old group and 88.9% of cases were in the 1 to 2 years old group. With respect to race/ethnicity and vaccination status of the cases, 39.46% of Hispanics, 32% of whites, and 50% of blacks were reported to be unvaccinated. CONCLUSIONS: Increasing pertussis vaccination coverage among children, as well as providing booster shots to adults with special attention on the Hispanic population, may prove to be an effective strategy for health departments.

Knowledge and Acceptability about Adult Pertussis Immunization in Korean Women of Childbearing Age.

PURPOSE: The adult tetanus, reduced diphtheria, and acellular pertussis (Tdap) vaccine has been introduced in order to provide individual protection and reduce the risk of transmitting pertussis to infants. We assessed the knowledge and acceptability of the Tdap vaccine around pregnancy. MATERIALS AND METHODS: This study was a cross-sectional survey of women of childbearing age (20-45 years) who visited obstetrics and gynecologic units of primary, secondary, or tertiary hospitals. They were asked to fill in a questionnaire assessing their knowledge, attitudes, and acceptability of Tdap. RESULTS: The questionnaire was completed by 308 women; 293 (95.1%) had not received information from doctors about Tdap, and 250 (81.2%) did not know about the need for vaccination. A significantly important factor related to subjects' intention to be vaccinated, identified by stepwise multiple logistic regression, was the knowledge (OR 13.5, CI 3.92-46.33) that adult Tdap is effective in preventing pertussis for infants aged 0-6 months. Additionally, 276 (89.6%) considered the recommendation of obstetric doctors as the most influencing factor about Tdap vaccination. CONCLUSION: In Korea, most women of childbearing age seem to be neither recommended nor adequately informed about the vaccination, although our population was not a nationwide representative sample. Information given by healthcare workers may be critical for improving awareness and preventing pertussis.

The pertussis epidemic: informing strategies for prevention of severe disease.

To assess the impact of Bordetella pertussis infections in South Australia during an epidemic and determine vulnerable populations, data from notification reports for pertussis cases occurring between July 2008 and December 2009 were reviewed to determine the distribution of disease according to specific risk factors and examine associations with hospitalizations. Although the majority (66%) of the 6230 notifications for pertussis occurred in adults aged >24 years, the highest notification and hospitalization rate occurred in infants aged <1 year. For these infants, factors associated with hospitalization included being aged <2 months [relative risk (RR) 2·3, 95% confidence interval (CI) 1·60-3·32], Indigenous ethnicity (RR 1·7, 95% CI 1·03-2·83) and receiving fewer than two doses of pertussis vaccine (RR 4·1, 95% CI 1·37-12·11). A combination of strategies aimed at improving direct protection for newborns, vaccination for the elderly, and reducing transmission from close contacts of infants are required for prevention of severe pertussis disease.

Pertussis (whooping cough) epidemiology in Waikato, New Zealand: 2000-2009.

AIM: To describe the epidemiology of pertussis in the Waikato region of New Zealand between 2000 and 2009, and to identify any differences in case characteristics between epidemic and non-epidemic periods. METHOD: Waikato pertussis notification data for the period 1 January 2000 to 31 December 2009 was analysed to identify any trends in the rates and distribution of key variables. Characteristics of case notifications were compared between an identified epidemic and non-epidemic period. RESULTS: Pertussis notification rates in the Waikato region were higher than national rates but followed a similar yearly pattern. Epidemics were identified in the years 2000 and 2004. The age distribution of pertussis cases changed over the decade with an increasing percentage in older age groups. Notification rates were higher in Europeans than Maori and in the least deprived NZDep group compared to the most deprived. In contrast, hospitalisation rates were higher in Maori than Europeans and in the most deprived NZDep groups. No clear differences in case characteristics were identified between an epidemic and non-epidemic period. CONCLUSION: The epidemiology of pertussis in Waikato is similar to that reported elsewhere in New Zealand. Further studies are required to clearly identify whether there are differences in case characteristics between epidemic and non-epidemic periods.

Infant and maternal risk factors for pertussis-related infant mortality in the United States, 1999 to 2004.

BACKGROUND: Infants aged <12 months have the highest rates of complications and death from pertussis of any age group. Factors that increase the risk of pertussis-related death in infants are not well defined. METHODS: The US Multiple Cause-of-Death and Linked Birth/Infant Death databases were used for 1999 to 2004 to examine pertussis-related infant mortality rates and to obtain anonymous records of infants with pertussis listed as a cause of death and of surviving infants. Infant and maternal characteristics present at the time of birth for infants who died with pertussis were compared with those of surviving infants. RESULTS: During 1999 to 2004, 91 infant deaths were reported with pertussis as a cause of death. All infants were 7 months or younger; 58% were age <2 months. The average annual infant mortality rate attributed to pertussis was 3.8 (95% CI: 3.0-4.6) per 1,000,000 live births, and 13.1 (95% CI: 9.8-17.1) per 1,000,000 live births for infants aged <2 months. Infant pertussis deaths showed an independent association with birth weight <2500 g, female sex, Apgar score <8, and mother with <12 years education. The mortality rate among Hispanic infants aged <2 months was 2.6 times greater than among non-Hispanic infants of similar age. CONCLUSIONS: Ensuring pertussis booster vaccination of adults and adolescents in close contact with an infant is warranted to prevent transmission of pertussis to vulnerable infants, particularly infants too young to be immunized. Special emphasis should be given to women and infant settings in which the risk of infant pertussis death might be increased.

Trends in pertussis among infants in the United States, 1980-1999.

CONTEXT: Reported cases of pertussis among adolescents and adults have increased since the 1980s, despite increasingly high rates of vaccination among infants and children. However, severe pertussis morbidity and mortality occur primarily among infants. OBJECTIVE: To describe the trends and characteristics of reported cases of pertussis among infants younger than 12 months in the United States from 1980 to 1999. DESIGN, SETTING, AND PARTICIPANTS: Cases of pertussis in infants younger than 12 months in the United States reported to the National Notifiable Disease Surveillance System of the Centers for Disease Control and Prevention between 1980 and 1999, and detailed case data from the Supplementary Pertussis Surveillance System. MAIN OUTCOME MEASURES: Incidence and demographic and clinical characteristics of cases. RESULTS: The incidence of reported cases of pertussis among infants increased 49% in the 1990s compared with the incidence in the 1980s (19 798 vs 12 550 cases reported; 51.1 cases vs 34.2 cases per 100 000 infant population, respectively). Increases in the incidence of cases and the number of deaths among infants during the 1990s primarily were among those aged 4 months or younger, contrasting with a stable incidence of cases among infants aged 5 months or older. The proportion of cases confirmed by bacterial culture was higher in the 1990s than in the 1980s (50% and 33%, respectively); the proportion of hospitalized cases was unchanged (67% vs 68%, respectively). Receipt of fewer doses of vaccine was associated with hospitalization, when cases were stratified by age in months. CONCLUSIONS: The incidence of reported cases of pertussis among infants increased in the 1990s compared with the 1980s. The limited age group affected, the increased rate of bacteriologic confirmation, and the unchanged severity of illness suggest that an increase in infant pertussis has occurred apart from any change in reporting. Strategies are needed to prevent the morbidity and mortality from pertussis among infants too young to be fully vaccinated, according to the current recommended schedules of vaccination in the United States.

The 1996 pertussis epidemic in New Zealand: descriptive epidemiology.

AIM: To describe the 1996 pertussis epidemic. METHODS: Hospitalisation, notification and laboratory data were used to describe the 1996 pertussis epidemic and compare it with previous epidemics. RESULTS: The 1996 epidemic spanned 24 months. The crude hospitalisation rate from 1 June 1995 to 31 May 1997, was 10.1 per 100,000 person years, being highest for children aged six weeks to two months (42 to 90 days old inclusive; 1402 per 100,000). The 1996 epidemic involved more hospitalisations than the 1991 and 1986 epidemics, and a greater proportion for children under the age of one year (77%), compared to previous epidemics (60-70%). There were no deaths. Pertussis only became notifiable from 1 June 1996. The crude notification rate for the following twelve months was 19.8 per 100,000 (equivalent hospitalisation rate 6.7 per 100,000); children aged six weeks to two months of age had the highest notification rate (531 per 100,000; equivalent hospitalisation rate 1021 per 100,000). In 1996-97, children aged under 15 months accounted for 21% of notifications, but 82% of hospitalisations. Europeans tended to have higher rates of notifications than non-Europeans, but lower rates of hospitalisation. CONCLUSIONS: New Zealand continues to experience high rates of pertussis as a result of inadequate immunisation coverage. The increase in hospitalisations during the 1996 epidemic may reflect a real increase in the population-based incidence, or other changes (e.g. hospitalisation practice, increase in vulnerable children with poor access to primary care). Improved rates, accuracy and completeness of pertussis notifications will improve the ability of notification data to accurately describe future epidemics and estimate vaccine effectiveness. Further debate is required regarding the aims of pertussis immunisation; accelerating the timing of the first three doses and adding further doses of pertussis vaccine on the national immunisation schedule; and the role of acellular pertussis vaccines. In the meantime, the priority must be increasing on-time immunisation coverage.

A comparison of two pertussis epidemics in Auckland.

AIM: To determine if the addition of the 6 week dose of pertussis vaccine in 1984 was associated with any change in the hospitalisation rate for children with pertussis and the higher hospitalisation rates for Maori and Pacific Islander children with pertussis. DESIGN: Population based study of pertussis hospitalisations using a retrospective chart review of hospitalisation data for children during the 1991 epidemic, which was compared to previously published data from the 1982 epidemic. SETTING: Princess Mary and Middlemore hospitals, Auckland. SUBJECTS: Children aged 0-14 years resident in metropolitan Auckland and hospitalised in Auckland during 1982 or 1991 with pertussis. MEASUREMENTS: Hospitalisation rates were calculated as number of children with a discharge diagnosis of pertussis per 1000 children aged 0-14 years based on 1981 and 1991 census data. 1982 data were converted to person-years as published report was for an 8 month period. Hospitalisation rates were compared as a relative risk (RR) of hospitalisation in 1991 versus 1982. RESULTS: There were 84 cases during 8 months in 1982 and 66 cases in 1991. Rates of hospitalisation by ethnic group; in 1982 were 0.24 Other/European (OE), 1.98 Maori (M), 1.37 Pacific Islander (PI); and in 1991 were 0.22 OE, 0.51 M, 0.40 PI. Compared to 1982 the relative risk of hospitalisation in 1991 adjusted for ethnicity was 0.43 (CI 0.33, 0.58, p < 0.0001). Compared to 1982 there was a significant reduction in the hospitalisation rate in 1991 for M (RR = 0.26, CI 0.16, 0.43, p < 0.0001); and PI children (RR = 0.29, CI 0.16, 0.54, p < 0.0001); but not for OE children (RR = 0.91, 95% CI 0.57, 1.46, p = 0.70). CONCLUSIONS: There was a significant reduction in the rate of hospitalisation for pertussis in 1991 compared to 1982. This reduction in hospitalisation rate was due to a reduction in rates for Maori and Pacific Islander children.

Effect of gender, race, and parental education on immunogenicity and reported reactogenicity of acellular and whole-cell pertussis vaccines.

OBJECTIVE: To determine whether gender, race (black or white), or level of parental education influenced serologic responses or reporting of clinical reactions after immunization with acellular (DTaP) or whole-cell (DTP) pertussis vaccine with diphtheria and tetanus toxoids combined. METHODS: Healthy infants were prospectively randomized to receive one of 13 DTaP, Lederle DTP, or another DTP. Parents recorded the occurrence of adverse reactions for 2 weeks after each inoculation. Sera obtained before the first immunization and 1 month after the third immunization were analyzed for antibody to pertussis toxin, filamentous hemagglutinin, fimbriae, and pertactin (PRN). Chinese hamster ovary cell pertussis toxin neutralization assays were performed, and levels of agglutinating antibodies determined. RESULTS: Prevaccination antibody levels did not differ by race, gender, or parental education. Postimmunization geometric mean titers (GMTs) were strongly and consistently associated with race. For both DTaP and DTP and for every included antigen, postimmunization GMTs were about twice as high for black as for white infants. Among DTaP recipients, these differences were significant for pertussis toxin, Chinese hamster ovary cell pertussis toxin neutralization assay, filamentous hemagglutinin, PRN, and agglutinins; among the much smaller sample of WCL recipients, the differences achieved or approached statistical significance for agglutinins, PRN, and fimbriae. These findings were confirmed by regression analyses that controlled for gender, parental education, study site, and preimmunization antibody level. Reported reactions were not correlated with parental education level and showed no material correlation with gender. Black infants were reported to have had more pain than white infants after receiving WCL and DTaP and were reported to be more fussy after receiving WCL. CONCLUSIONS: The consistently higher postimmunization GMTs among black infants seems to be a real finding for which we have no explanation; the infants did not significantly differ by race in vaccine assignment, preimmunization antibody levels, age at immunization, or interval from immunization to phlebotomy. These observations should be confirmed and further evaluated in future pertussis vaccine trials. Reported differences by race in pain and fussiness after receiving WCL might reflect chance, differences by race in the occurrence of reactions, or differences by race in the reporting of reactions.

The 1993 epidemic of pertussis in Cincinnati. Resurgence of disease in a highly immunized population of children.

BACKGROUND: In 1993 there was a resurgence of pertussis in the United States. Altogether, 6335 cases were reported, the most in 26 years. METHODS: Using active microbiologic surveillance, we investigated the epidemic of pertussis in Greater Cincinnati in 1993. The population of 1.7 million in this area is served by a single children's hospital and pertussis laboratory. We prospectively followed patients given a new diagnosis of pertussis in July through September 1993 to determine the characteristics of the epidemic. RESULTS: From 1979 to 1992, there was a cumulative total of 542 cases of pertussis. In 1993, 352 cases were diagnosed, an increase of 259 percent over the 1992 total. Sixty-three percent of the cases had positive cultures for Bordetella pertussis, 18 percent were positive on direct fluorescent-antibody testing only, and 19 percent were diagnosed clinically. The outbreak began in the suburbs during the summer and spread through Greater Cincinnati. Of 255 total cases diagnosed in July through September (195 excess cases over the maximal base-line level of 20 per month in the previous 14 years), 75 percent were in white patients and 67 percent of the patients had private insurance or paid for care out of pocket. In 1993, as compared with 1979 through 1992, there was a shift in incidence from younger infants to older children; the percentages of cases according to age group were as follows: 0 to 6 months, 53 percent from 1979 through 1992 and 35 percent in 1993 (P < 0.001); 7 months to 5 years, 33 percent and 43 percent (P < 0.002); 6 to 12 years, 5 percent and 11 percent (P < 0.001); and more than 12 years, 5 percent and 11 percent (P < 0.003). Immunization records revealed that 74 percent (75 of 101) of the children with pertussis who were 19 months to 12 years old had received four or five doses of the combined diphtheria-pertussis-tetanus (DPT) vaccine, and that 82 percent (103 of 126) of those 7 to 71 months old had received at least three doses of DPT vaccine. The whole-cell vaccines used came from both of the major manufacturers (Connaught Laboratories and Lederle Laboratories). Disease was not severe, but 80 of the 255 children (31 percent) given diagnoses during the three epidemic months were hospitalized. There were no deaths. CONCLUSIONS: Since the 1993 pertussis epidemic in Cincinnati occurred primarily among children who had been appropriately immunized, it is clear that the whole-cell pertussis vaccine failed to give full protection against the disease.

The 1985 national immunisation survey: diphtheria, tetanus, and pertussis (whooping cough)

In April 1985 a national immunisation survey was conducted in which sera were collected from almost 3000 randomly selected children throughout New Zealand. The sera collected were from about 1000 new school entrants (mean age 5 years), 1000 standard 3 students (mean age 10 years), and 1000 form 4 students (mean age 15 years). The sera were tested for diphtheria and tetanus immunity and antibody to pertussis by enzyme-linked immunosorbent assay (ELISA) tests. The percentage of those immune to diphtheria decreased with age from 73.1% in the 5 year olds to 53.7% in the 15 year olds. The percentage of those immune to tetanus decreased with age from 66.9% in the 5 year olds to 54.6% in the 10 year olds but then increased to 64.0% in the 15 year olds. While more than 71.0% of the 10 and 15 year olds had measurable antibody to pertussis, only a low 54.4% of the 5 year olds did. The proportion immune to diphtheria and tetanus in both Maoris and Europeans was approximately similar in all three age groups. More Maoris (78.9%) than Europeans (66.1%) had antibody to pertussis. When the data had been standardised for age and ethnic group the percentage with antibody to pertussis and immunity to diphtheria was highest in the southern region, while for tetanus immunity the percentage immune was highest in the northern and southern regions. We conclude that a sizeable pool of new school entrants (mean age 5 years) without antibody to pertussis is accumulating at a time when pertussis still persists.(ABSTRACT TRUNCATED AT 250 WORDS)