Evidence of Bordetella pertussis infection in vaccinated 1-year-old Danish children

We measured IgA and IgG antibodies to pertussis toxin (PT) and filamentous hemagglutinin (FHA) in sera from 203 1-year-old children who had received one to three doses of a monocomponent PT toxoid vaccine. Ten children (5%) had IgA antibody to PT indicating recent infection; seven of these children had received three doses of vaccine. PT IgA responders did not have significantly longer coughing episodes than PT IgA non-responders. Since an IgA antibody response occurs in only ∼50% of infected children, the actual infection rate in our cohort is estimated to ∼10%. The apparent high Bordetella pertussis infection rate in Danish infants suggests that the monocomponent PT toxoid vaccine used in Denmark has limited efficacy against B. pertussis infection. A prospective immunization study comparing a multi-component vaccine with the present monocomponent PT toxoid vaccine should be undertaken

The epidemiology of pertussis in Germany: past and present

<p>Abstract</p> <p>Background</p> <p>Current and past pertussis epidemiology in the two parts of Germany is compared in the context of different histories of vaccination recommendations and coverage to better understand patterns of disease transmission.</p> <p>Methods</p> <p>Available regional pertussis surveillance and vaccination coverage data, supplemented by a literature search for published surveys as well as official national hospital and mortality statistics, were analyzed in the context of respective vaccination recommendations from 1964 onwards.</p> <p>Results</p> <p>Routine childhood pertussis vaccination was recommended in the German Democratic Republic (GDR) from 1964 and in former West German states (FWG) from 1969, but withdrawn from 1974–1991 in FWG. Pertussis incidence declined to <1 case/100.000 inhabitants in GDR prior to reunification in 1991, while in FWG, where pertussis was not notifiable after 1961, incidence was estimated at 160–180 cases/100.000 inhabitants in the 1970s-1980s. Despite recommendations for universal childhood immunization in 1991, vaccination coverage decreased in former East German States (FEG) and increased only slowly in FWG. After introduction of acellular pertussis vaccines in 1995, vaccination coverage increased markedly among younger children, but remains low in adolescents, especially in FWG, despite introduction of a booster vaccination for 9–17 year olds in 2000. Reported pertussis incidence increased in FEG to 39.3 cases/100.000 inhabitants in 2007, with the proportion of adults increasing from 20% in 1995 to 68% in 2007. From 2004–2007, incidence was highest among 5–14 year-old children, with a high proportion fully vaccinated according to official recommendations, which did not include a preschool booster until 2006. Hospital discharge statistics revealed a ~2-fold higher pertussis morbidity among infants in FWG than FEG.</p> <p>Conclusion</p> <p>The shift in pertussis morbidity to older age groups observed in FEG is similar to reports from other countries with longstanding vaccination programs and suggests that additional booster vaccination may be necessary beyond adolescence. The high proportion of fully vaccinated cases in older children in FEG suggests waning immunity 5–10 years after primary immunisation in infancy. The higher incidence of pertussis hospitalisations in infants suggests a stronger force of infection in FWG than FEG. Nationwide pertussis reporting is required for better evaluation of transmission patterns and vaccination policy in both parts of Germany.</p

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

BACKGROUND: Pertussis (whooping cough) is well known to be underreported, particularly among adults, who can act as an infectious reservoir, potentially putting susceptible newborns at risk of serious illness. The purpose of this study was to estimate the seroprevalence of pertussis in adults in Hungary. METHODS: This epidemiological, cross-sectional study was conducted in adults in five general practitioners' practices in Hungary. Serum anti-pertussis toxin immunoglobulin G (anti-PT IgG) antibody levels were analyzed using enzyme-linked immunosorbent assay. Sera were classified following manufacturer's instructions as: strongly indicative of current/recent infection (>/=1.5 optical density [OD] units); indicative of current/recent infection (>/=1.0 OD units); seropositive (>0.3 OD units); or seronegative (/=60 years (odds ratio [OR], 1.97; 95% confidence interval [CI], 1.39-2.80; p = .0002) or 18-29 years (OR, 1.67; 95% CI, 1.13-2.46; p = .0094) vs. 45-59 years; former smoker (OR, 1.46; 95% CI, 1.08-1.97; p = .014) or current smoker (OR, 1.38; 95% CI, 1.01-1.89; p = .045) vs. never smoker; and male (OR, 1.30; 95% CI, 1.01-1.68; p = .041) vs. female. Also, between increased rates of probable current/recent infection and current smoker (OR, 7.50; 95% CI, 2.32-24.31; p = .0008) or former smoker (OR, 4.07; 95% CI, 1.21-13.64; p = .023) vs. never smoker. CONCLUSIONS: Approximately 85% of the adults studied were seronegative and therefore susceptible to pertussis infection. Approximately 1% had anti-PT IgG levels indicative of current/recent pertussis infection, which could potentially be transmitted to susceptible young infants. Vaccination of adults is a key way to indirectly protect infants. TRIAL REGISTRATION: Clinical Trials.gov NCT02014519 . Prospectively registered 12 December 2013

Immune Boosting Explains Regime-Shifts in Prevaccine-Era Pertussis Dynamics

Understanding the biological mechanisms underlying episodic outbreaks of infectious diseases is one of mathematical epidemiology’s major goals. Historic records are an invaluable source of information in this enterprise. Pertussis (whooping cough) is a re-emerging infection whose intermittent bouts of large multiannual epidemics interspersed between periods of smaller-amplitude cycles remain an enigma. It has been suggested that recent increases in pertussis incidence and shifts in the age-distribution of cases may be due to diminished natural immune boosting. Here we show that a model that incorporates this mechanism can account for a unique set of pre-vaccine-era data from Copenhagen. Under this model, immune boosting induces transient bursts of large amplitude outbreaks. In the face of mass vaccination, the boosting model predicts larger and more frequent outbreaks than do models with permanent or passively-waning immunity. Our results emphasize the importance of understanding the mechanisms responsible for maintaining immune memory fo

Estimating the Duration of Pertussis Immunity Using Epidemiological Signatures

Case notifications of pertussis have shown an increase in a number of countries with high rates of routine pediatric immunization. This has led to significant public health concerns over a possible pertussis re-emergence. A leading proposed explanation for the observed increase in incidence is the loss of immunity to pertussis, which is known to occur after both natural infection and vaccination. Little is known, however, about the typical duration of immunity and its epidemiological implications. Here, we analyze a simple mathematical model, exploring specifically the inter-epidemic period and fade-out frequency. These predictions are then contrasted with detailed incidence data for England and Wales. We find model output to be most sensitive to assumptions concerning naturally acquired immunity, which allows us to estimate the average duration of immunity. Our results support a period of natural immunity that is, on average, long-lasting (at least 30 years) but inherently variable

What to do and what not to do in serological diagnosis of pertussis: recommendations from EU reference laboratories

International audience-specific antibodies can be detected by enzyme-linked immunosorbent assays (ELISAs) or multiplex immunoassays. Assays use purified or mixed antigens, and only pertussis toxin (PT) is specific for . The interpretation of results can be based on dual-sample or single-sample serology using one or two cut-offs. The EU Pertstrain group recommends that: (i) ELISAs and multiplex immunoassays should use purified non-detoxified PT as an antigen, that they should have a broad linear range and that they should express results quantitatively in International Units per millilitre (IU/ml); (ii) a single or dual diagnostic cut-off for single-serum serology using IgG-anti-PT between 50 and 120 IU/ml should be used, and diagnostic serology cannot be validly interpreted for one year after vaccination with acellular pertussis (aP) vaccines; (iii) IgA-anti-PT should only be used with indeterminate IgG-anti-PT levels or when a second sample cannot be obtained. This group discourages using: (i) other antigens in routine diagnostics, as they are not specific; (ii) micro-agglutination, due to its lack of sensitivity; (iii) immunoblots for pertussis serodiagnosis, as results cannot be quantified; (iv) other methods, such as complement fixation or indirect immunofluorescence, due to their low sensitivity and/or specificity