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

Real-time polymerase chain reaction on filter paper spotted samples: a gateway to molecular diagnosis of invasive bacterial diseases for rural areas in low-income countries

BACKGROUND

Bacterial culture is the gold standard for the diagnosis of invasive bacterial diseases (IBDs) but molecular methods are more specific and sensitive. Fresh liquid samples (FLSs) show patent limitations for shipping and storage. We aimed to evaluate the sensitivity and specificity of real-time polymerase chain reaction (PCR) performed on dried sample spots (DSSs) obtained from different biological fluids compared with real-time PCR or culture performed on FLSs.

METHODS

FLSs positive for Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, Bordetella pertussis and/or Pseudomonas aeruginosa were spotted on filter paper. Real-time PCR was performed on both FLSs and DSSs and results were compared. The stability of the DSS results over time was evaluated.

RESULTS

Real-time PCR performed on 114 DSSs showed a specificity of 99.1% and a sensitivity of 91.2% for IBD diagnosis. A positive correlation was found between FLS cycle threshold (Ct) and DSS Ct (r=0.84; r2=0.71) with the Pearson statistical test and Bland-Altman analysis showing that 95% of the specimens were within agreeable limits. Although we observed a trend towards signal reduction over time in the DSSs, there was no statistical evidence of an increase in Ct values. Real-time PCR on DSSs was 2.2 times more sensitive than culture.

CONCLUSIONS

Real-time PCR applied to DSSs may be a useful approach in different situations, such as IBD diagnosis, both for rural areas of low-income countries and family practitioners in various settings.

The data used to build the models: Pertussis morbidity and mortality burden considering various Brazilian data sources

BACKGROUND

Pertussis is associated with significant disease burden in children worldwide. In addition to its cyclical nature, resurgences of pertussis cases, hospitalizations and deaths have been reported by many countries. We describe the dynamics of pertussis in Brazil, a middle-income country that has experienced a resurgence and that provides good quality data to allow building a dynamic transmission disease model.

METHODS

We conducted a descriptive analysis of pertussis burden considering data from the national disease surveillance system, national hospitalization information system and national mortality registry. Study period was 2000-2016. Absolute numbers and rates per 100,000 inhabitants over time, by age sub-groups and geographical regions are presented.

RESULTS

From 2000 to 2016, a total of 37,299 reported pertussis cases, 25,240 hospitalizations, and 601 deaths due to pertussis were reported. Although the outcomes - pertussis cases, hospitalizations, and deaths - come from independent information systems, our results document low disease burden with periodic increases every 3-4 years during the years 2000-2010, followed by a sharp increase which peaked in 2014. In both periods, disease burden is concentrated in young children, while its more serious outcomes - hospitalizations and deaths, are concentrated in infants. Pre-outbreak and outbreak disease burden as well as timing of peak during the outbreak period vary by states and within geographical regions, representing valuable resources of data for modelling purposes.

CONCLUSION

Consistent disease burden patterns were observed over time in Brazil using a variety of data sources. Given the scarcity of good epidemiological data on pertussis available from low- and middle-income countries, our reported data provide valuable information for the assessment of the public health impact and cost-effectiveness modelling studies of newer strategies to prevent and control pertussis. These data were used to build and calibrate a national dynamic transmission model, which was used to evaluate the cost-effectiveness of maternal immunization. Clinical Trial registry name and registration number: Not applicable.

Alarm Thresholds for Pertussis Outbreaks in Iran: National Data Analysis

Objectives

The purpose of the current study was to determine the upper threshold number of cases for which pertussis infection would reach an outbreak level nationally in Iran.

Methods

Data on suspected cases of pertussis from the 25^th February 2012 to the 23^rd March 2018 from the Center for Disease Control and Prevention in Iran was used. The national upper threshold level was estimated using the exponentially weighted moving average (EWMA) method and the Poisson regression method.

Results

In total, 2,577 (33.6%) and 1,714 (22.3%) cases were reported in the Spring and Summer respectively. There were 1,417 (18.5%) and 1,971 (25.6%) cases reported in the Autumn and Winter, respectively. The overall upper threshold using the EWMA and the Poisson regression methods, was estimated as a daily occurrence of 8 (7.55) and 7.50 (4.48–11.06) suspected cases per 10,000,000 people, respectively. The daily seasonal thresholds estimated by the EWMA and the Poisson regression methods were 10, 7, 6, 8 cases and 10, 7, 7, 9 cases for the Spring, Summer, Autumn, and Winter, respectively.

Conclusion

The overall and seasonal estimated thresholds by the 2 methods were similar. Therefore, the estimated thresholds of 6–10 cases in a day, per 10,000,000 people could be used to detect pertussis outbreaks and epidemics by health policymakers.

Pertussis in Latin America and the Hispanic Caribbean: a systematic review

Introduction: Pertussis in Latin America continues to cause periodic epidemics with substantial morbidity particularly among young children. The disease has persisted despite long-standing vaccination programs in the region. Areas covered: We conducted a systematic review to characterize the recent epidemiology of pertussis in Latin America and Hispanic Caribbean. We undertook a holistic approach and attempted to include all available data concerning pertussis that may explain the changing dynamics of the disease. Expert opinion: There are wide disparities in the reported annual incidence rates of pertussis both within and between countries in the region. General trends in pertussis incidence are difficult to ascertain due to the heterogeneity in the epidemiological data. Available data suggests that the disease burden has changed over the years such that now it predominantly affects those <1 year. Coverage with three doses of the pertussis vaccine has been highly variable, and very few countries have consistently achieved ≥90% coverage annually since 2000. There remain inequalities in vaccination coverage in some regions/localities and specific groups, which sustains the risk of pertussis dissemination. The WHO considers that maternal pertussis immunization provides protection to infants too young to be vaccinated; >10 Latin American countries currently recommend vaccination of pregnant women.

Assessing the Importance of Domestic Vaccine Manufacturing Centers: An Overview of Immunization Programs, Vaccine Manufacture, and Distribution

Vaccines have significantly reduced the detrimental effects of numerous human infectious diseases worldwide, helped to reduce drastically child mortality rates and even achieved eradication of major pathogens, such as smallpox. These achievements have been possible due to a dedicated effort for vaccine research and development, as well as an effective transfer of these vaccines to public health care systems globally. Either public or private institutions have committed to developing and manufacturing vaccines for local or international population supply. However, current vaccine manufacturers worldwide might not be able to guarantee sufficient vaccine supplies for all nations when epidemics or pandemics events could take place. Currently, different countries produce their own vaccine supplies under Good Manufacturing Practices, which include the USA, Canada, China, India, some nations in Europe and South America, such as Germany, the Netherlands, Italy, France, Argentina, and Brazil, respectively. Here, we discuss some of the vaccine programs and manufacturing capacities, comparing the current models of vaccine management between industrialized and developing countries. Because local vaccine production undoubtedly provides significant benefits for the respective population, the manufacture capacity of these prophylactic products should be included in every country as a matter of national safety.