Evaluation of reported cases of pertussis: epidemiological study in a large city in Spain

Epidemiology, prevention and control of pertussis in Spain: New vaccination strategies for lifelong protection

Pertussis is a highly contagious, vaccine-preventable respiratory tract infection, with high morbidity and mortality and a particularly severe effect on newborns and infants under 2 months. The first pertussis vaccines were introduced in the 1940s. Since 1980, however, the incidence of cases has risen despite the extensive vaccination programmes and antibiotic adjuvant treatments available. Transition from the use of whole-cell vaccines to acellular vaccines and the antigenic modifications of Bordetella pertussis have contributed, among other factors, to a reduction in vaccine-acquired immunity and reemergence of the disease. Today, there are still unmet needs not covered by conventional prevention measures and existing antibiotic treatments. This review aims to update the available data, and to discuss which vaccine strategies might contribute to better disease control and prevention.

Epidemiology, prevention and control of pertussis in Spain: New vaccination strategies for lifelong protection

Pertussis is a highly contagious, vaccine-preventable respiratory tract infection, with high morbidity and mortality and a particularly severe effect on newborns and infants under 2 months. The first pertussis vaccines were introduced in the 1940s. Since 1980, however, the incidence of cases has risen despite the extensive vaccination programmes and antibiotic adjuvant treatments available. Transition from the use of whole-cell vaccines to acellular vaccines and the antigenic modifications of Bordetella pertussis have contributed, among other factors, to a reduction in vaccine-acquired immunity and reemergence of the disease. Today, there are still unmet needs not covered by conventional prevention measures and existing antibiotic treatments. This review aims to update the available data, and to discuss which vaccine strategies might contribute to better disease control and prevention.

A multi-country, multi-year, meta-analytic evaluation of the sex differences in age-specific pertussis incidence rates

BACKGROUND

Pertussis is frequently reported to be more common in females than in males. However, the variability of the sources of these observations makes it difficult to estimate the magnitude and consistency of the sex differences by age. To address this question, we used meta-analytic methods to analyze pertussis national incidence rates by sex and age group from nine countries between the years 1990 and 2017.

METHODS

For each age group, we used meta-analytic methods to combine the female to male incidence rate ratios (RRs) by country and year. Meta-regression was performed to assess the relative contributions of age, country and time-period to the variation in the incidence RRs.

RESULTS

The pooled female to male incidence RRs (with 95% CI) for ages 0-1, 1-4, 5-9 and 10-14, were 1.03 (1.01-1.06), 1.16 (1.14-1.17), 1.18 (1.15-1.22), 1.15 (1.11-1.18) respectively. For the ages 15-44, 45-64 and 65+ they were 1.65 (1.58-1.72), 1.59 (1.53-1.66), 1.20 (1.16-1.24), respectively. While there were some differences between the countries, the directions were consistent. When including age, country and time in meta-regression analyses, almost all the variation could be attributed to the differences between the age groups.

CONCLUSIONS

The consistency of the excess pertussis incidence rates in females, particularly in infants and very young children, is unlikely to be due to differences in exposure. Other factors that impact on the immune system, including chromosomal differences and hormones, should be further investigated to explain these sex differences. Future studies should consider sex for better understanding the mechanisms affecting disease incidence, with possible implications for management and vaccine development.

Pertussis outbreak investigation in Janamora district, Amhara Regional State, Ethiopia: a case-control study

Introduction

On April 17/2017 Janamora district, Amhara regional state health officials reported an increasing number of people with a cough. The objectives of this study was to investigate the outbreak, describe risk factors and implement control measures.

Methods

We conducted a community based unmatched 1:1 case-control study April 22-May 10, 2017. We used a probable case definition (≥2 weeks cough with vomiting, apnea, or inspiratory whoop) to identify suspected pertussis cases. Neighbors of cases were considered as controls. We conducted a door-to-door active case search and reviewed medical records, assessed vaccination status by parental interview or vaccination card. We implemented multivariable logistic regression to identify independent factors associated with the outbreak.

Results

We investigated 60 cases and 60 controls. Most (68.3%) of the cases were under the age of 15. The majority (86.6%) of pertussis suspected cases, and 83.4% controls had not received any pertussis vaccine. The overall attack rate was 0.13% and the case fatality rate was 3.3%. The age-specific attack rate for under-five children was 0.33%. Females were more likely to have pertussis (AOR: 2.91; 95% CI: 1.17-7.22), contact with pertussis suspected person (AOR: 6.29; 95% CI: 2.53-15.62) and living in a relatively poorly ventilated house (AOR: 3.01; 95% CI: 1.17-7.70) were also significant risk factors of pertussis.

Conclusion

Weak supplementary immunization activities might have contributed to the outbreak. Treating household contacts and integration of diagnostic laboratory test of pertussis into the local health system is of paramount importance to detect outbreaks early on.

Airborne bioaerosols and their impact on human health

Bioaerosols consist of aerosols originated biologically such as metabolites, toxins, or fragments of microorganisms that are present ubiquitously in the environment. International interests in bioaerosols have increased rapidly to broaden the pool of knowledge on their identification, quantification, distribution, and health impacts (e.g., infectious and respiratory diseases, allergies, and cancer). However, risk assessment of bioaerosols based on conventional culture methods has been hampered further by several factors such as: (1) the complexity of microorganisms or derivatives to be investigated; (2) the purpose, techniques, and locations of sampling; and (3) the lack of valid quantitative criteria (e.g., exposure standards and dose/effect relationships). Although exposure to some microbes is considered to be beneficial for health, more research is needed to properly assess their potential health hazards including inter-individual susceptibility, interactions with non-biological agents, and many proven/unproven health effects (e.g., atopy and atopic diseases).

Are pertussis cases reported too late for public health interventions? Retrospective analysis of cases in London and South East England, 2010 to 2015

In the United Kingdom, pertussis guidance recommends prophylaxis for household contacts within 21 days of case symptom onset if the household includes a vulnerable contact. The aim of our study was to identify characteristics associated with cases reported late for public health action. We reviewed the epidemiology of cases reported in London and South East England for the period 2010 to 2015. We characterised risk factors associated with late reporting of cases and described public health actions taken on timely reported cases. From 2010 to 2015, 9,163 cases of pertussis were reported to health protection teams. Only 11% of cases were reported within 21 days of onset, limiting opportunities for secondary prevention. Timely reporting was associated with younger age groups, pregnancy, being a healthcare worker and being reported by schools or hospital clinicians. Late reporting was associated with older age groups and general practitioner or laboratory reporting. Delays, such as those due to insidious onset and late presentation to healthcare, may be unavoidable; however, delay in reporting once a patient presents can be reduced since cases can be reported before laboratory confirmation. Thus we recommend working with clinicians and laboratories to determine causes and improve early reporting to public health.

Real-Time Polymerase Chain Reaction-Based Detection of Bordetella pertussis in Mexican Infants and Their Contacts: A 3-Year Multicenter Study

OBJECTIVES

To evaluate the usefulness of real-time polymerase chain reaction (RT-PCR) as a diagnostic method for the detection of Bordetella pertussis in hospitalized patients aged <1 year with a clinical diagnosis of whooping cough, as well as to identify the role of household contacts as a source of infection.

STUDY DESIGN

This was a prospective, multicenter study of infants aged <1 year who were hospitalized with symptoms suggestive of whooping cough. Nasopharyngeal samples were obtained for culture and RT-PCR testing. The clinical and epidemiologic characteristics and outcomes were analyzed. B pertussis detection and symptoms in household contacts of patients diagnosed with pertussis were studied.

RESULTS

A total of 286 patients were included; of these, 67.1% had B pertussis and 4.5% had Bordetella spp. Complications occurred in 20% of patients, and the mortality rate was 6.7%. Of 434 contacts studied, 111 were mothers of study infants, representing the most frequently B pertussis-infected group and the main symptomatic contact.

CONCLUSION

The use of RT-PCR permits improved detection and diagnosis of pertussis and a better understanding of the epidemiology of sources of infection. The complications and mortality rate of pertussis continue to be high. Household contacts are confirmed as a frequent source of infection of B pertussis in young children.

Epidemiology of pertussis in two Ibero-American countries with different vaccination policies: lessons derived from different surveillance systems

Background

Pertussis is a re-emerging disease worldwide despite its high vaccination coverage. European and Latin-American countries have used different surveillance and vaccination policies against pertussis. We compared the epidemiology of this disease in two Ibero-American countries with different vaccination and surveillance policies.

Methods

We compared the epidemiology of pertussis in Spain and the Dominican Republic (DR). We present a 10-year observational study of reported pertussis based on suspected and/or probable cases of pertussis identified by the national mandatory reporting system in both countries between 2005 and 2014. Both countries have a similar case definition for pertussis surveillance, although Spain applies laboratory testing, and uses real time PCR and/or culture for case confirmation while in DR only probable and/or suspected cases are reported. We analyzed incidence, hospitalization, case-fatality rates, mortality and vaccination coverage.

Results

The average annual incidence in children aged <1 year was 3.40/100,000 population in Spain and 12.15/100,000 in DR (p = 0.01). While the incidence in DR was generally higher than in Spain, in 2011 it was six times higher in Spain than in DR. The highest infant mortality in Spain was 0.017/100,000 in 2011, and the highest in DR was 0.08/100,000 in 2014 (p = 0.01). The proportion of hospitalized cases per year among children <1 year varied between 22.0% and 93.7% in Spain, and between 1.1% and 29.4% in DR (p = 0.0002), while mortality varied from 0 to 0.017 and 0 to 0.08 per 100,000 population in Spain and DR, respectively (p = 0.001). Vaccination coverage was 96.5% in Spain and 82.2% in DR (p = 0.001).

Conclusions

Pertussis is a public health problem in both countries. Surveillance, prevention and control measures should be improved, especially in DR. Current vaccination programs are not sufficient for preventing continued pertussis transmission, even in Spain which has high vaccination coverage.

Underdetection and underreporting of pertussis in children attended in primary health care centers: Do surveillance systems require improvement?

BACKGROUND

Pertussis is an underestimated disease. Several European countries have developed models to account for underreporting of pertussis. The aim of this study was to estimate pertussis underdetection and underreporting in pediatric patients attending primary health care centers (PHCCs).

METHODS

We reviewed clinical records of PHCCs in Barcelona in 2012. Factors associated with underdetection and underreporting were analyzed by logistic regression. Adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

We included 3,505 children aged < 7 years (mean age, 34  ±  20.7 months; range, 0-82 months) presenting with cough; 9.3% (326 out of 3,505) of patients also had ≥ 1 symptoms related to pertussis accompanied by cough for a duration ≥ 2 weeks. Of the 326 children receiving clinical criteria, only 31 (9.5%) were laboratory-confirmed and 6 (1.8%) were detected but not reported. There were 295 (90.5%) undetected suspected pertussis cases. Age ≥ 18 months (aOR, 8.51; 95% CI, 1.82-39.86), cyanosis (aOR, 6.71; 95% CI, 1.43-31.39), request for chest radiograph (aOR, 0.26; 95% CI, 0.07-0.99), and request for other laboratory tests (aOR, 5.39; 95% CI, 2.19-13.27) were associated with underdetection. Paroxysmal cough (aOR, 5.77; 95% CI, 1.05-31.76) and request for other laboratory tests (aOR, 2.91; 95% CI, 1.11-7.62) were associated with underreporting.

CONCLUSIONS

Both underdetection and underreporting complicate the understanding of pertussis epidemiology. Correct assessment of pertussis symptoms and notification of cases must be improved to control pertussis.