Pertussis resurgence in a highly vaccinated population, Mazandaran, North of Iran 2008-2011: an epidemiological analysis

The role of Bordetella pertussis in the development of multiple sclerosis

Background

Multiple sclerosis (MS) is one of the most common neurological disorders which main cause is not identified yet. Some studies mentioned the possible role of infectious agents such as chlamydia pneumonia, mycoplasma and also, B. pertussis via asymptomatic nasopharyngeal colonization. The current study aimed to investigate and compared the serum level of B. pertussis antibody and the rate of nasopharyngeal colonization by this pathogen in subjects with and without MS.

Methods

In this case-control study, 109 patients with MS and 114 subjects without MS referred to Sina Hospital in Hamadan in 2019 are studied and compared in terms of serum titer of B. pertussis antibody and nasopharyngeal colonization by this bacterium. Colonization was evaluated using culture and real-time PCR techniques. Data were analyzed using SPSS version 16 with a 95% confidence interval.

Results

The serum titer of B. pertussis antibody in case and control groups was 37.8 and 35.1%, respectively (P = 0.74). Culture and real-time PCR techniques revealed no case of nasopharyngeal colonization by B. pertussis.

Conclusion

There was no difference between B. pertussis antibody titer and the rate of nasopharyngeal colonization between both MS patients and the healthy control group. Therefore, it seems that probably B. pertussis has not a role in MS development.

Bordetella pertussis in School-Age Children, Adolescents, and Adults: A Systematic Review of Epidemiology, Burden, and Mortality in the Middle East

Despite modern diphtheria-tetanus-pertussis (DTP) vaccines and high vaccine coverage, a resurgence of pertussis (whooping cough) has been observed globally. In North America and Europe, high vaccine coverage in children has led to a shift in the age-specific peak incidence of infection away from infants and towards older children and adolescents. However, much less is known about the prevalence of pertussis in older children and adults in the Middle East. A systematic search of MEDLINE, EMBASE, and BIOSIS was undertaken to identify studies published between 1 January 1990 and 17 June 2019, with information on pertussis epidemiology, burden of illness, and mortality in school-aged children, adolescents, and adults in the Middle East. Studies identified for inclusion were reviewed narratively because a statistical comparison was not possible because of the mix of methodologies used. The results showed that surveillance data are weak or missing in most Middle Eastern countries, and among 24 epidemiological studies identified, most were from Iran (14), Israel (4), and Turkey (3), with single studies from the United Arab Emirates and Iraq. Despite various surveillance periods, clinical definitions, and antibody cut-off values used across the studies, the reported seroprevalence of pertussis antibodies suggested that adolescents and adults are commonly exposed to pertussis in the community and that vaccine-acquired immunity from childhood wanes. Few countries in the Middle East include a diphtheria-tetanus-acellular pertussis (Tdap) booster for adolescents on the national schedule. Israel was the only country with epidemiological data in a population that received Tdap, and the study showed that after the introduction of the adolescent booster dose, there was decrease in pertussis among children aged 5–14 years. To conclude, results from the Middle East suggest that in common with other regions, pertussis is widely circulating and that it might be shifting towards older age groups.

The burden of laboratory-confirmed pertussis in low- and middle-income countries since the inception of the Expanded Programme on Immunisation (EPI) in 1974: a systematic review and meta-analysis

BACKGROUND

An effective vaccine against Bordetella pertussis was introduced into the Expanded Programme on Immunisation (EPI) by WHO in 1974, leading to a substantial global reduction in pertussis morbidity and mortality. In low- and middle-income countries (LMICs), however, the epidemiology of pertussis remains largely unknown. This impacts negatively on pertussis control strategies in these countries. This study aimed to systematically and comprehensively review published literature on the burden of laboratory-confirmed pertussis in LMICs over the 45 years of EPI.

METHODS

Electronic databases were searched for relevant literature (1974 to December 2018) using common and MeSH terms for pertussis. Studies using PCR, culture or paired serology to confirm Bordetella pertussis and parapertussis in symptomatic individuals were included if they had clearly defined numerators and denominators to determine prevalence and mortality rates.

RESULTS

Eighty-two studies (49,167 participants) made the inclusion criteria. All six WHO regions were represented with most of the studies published after 2010 and involving mainly upper middle-income countries (n = 63; 77%). PCR was the main diagnostic test after the year 2000. The overall median point prevalence of PCR-confirmed Bordetella pertussis was 11% (interquartile range (IQR), 5-27%), while culture-confirmed was 3% (IQR 1-9%) and paired serology a median of 17% (IQR 3-23%) over the period. On average, culture underestimated prevalence by 85% (RR = 0.15, 95% CI, 0.10-0.22) compared to PCR in the same studies. Risk of pertussis increased with HIV exposure [RR, 1.4 (95% CI, 1.0-2.0)] and infection [RR, 2.4 (95% CI, 1.1-5.1)]. HIV infection and exposure were also related to higher pertussis incidences, higher rates of hospitalisation and pertussis-related deaths. Pertussis mortality and case fatality rates were 0.8% (95% CI, 0.4-1.4%) and 6.5% (95% CI, 4.0-9.5%), respectively. Most deaths occurred in infants less than 6 months of age.

CONCLUSIONS

Despite the widespread use of pertussis vaccines, the prevalence of pertussis remains high in LMIC over the last three decades. There is a need to increase access to PCR-based diagnostic confirmation in order to improve surveillance. Disease control measures in LMICs must take into account the persistent significant infant mortality and increased disease burden associated with HIV infection and exposure.

A systematic review of the burden of pertussis disease in infants and the effectiveness of maternal immunization against pertussis

Introduction Infants too young to be fully immunized are the most vulnerable to severe pertussis disease. To close this susceptibility gap, passive infant immunization through vaccination of pregnant women against pertussis was first introduced in 2011 in the United States and has been extended since then to more than 40 countries. Areas covered We conducted two systematic literature searches to describe the worldwide burden of pertussis disease in infants <6 months of age since 2005, and the effectiveness and impact of maternal pertussis vaccination in preventing infant pertussis since 2011. Expert opinion Pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Virtually all pertussis deaths occurred in this age group. Data from Africa, Eastern Mediterranean, and Asia were limited, but suggest a similar or higher disease burden than in Europe or the Americas. Estimates of effectiveness of second/third trimester pertussis vaccination in preventing pertussis disease in <2-3 months old infants were consistently high (69%-93%) across the observational studies reviewed, conducted in various settings with different designs. Maternal vaccination programs appear to be achieving their goal of reducing the burden of disease in very young infants. Plain language summary What is the context? Pertussis, also known as whooping cough, is a highly contagious disease of the respiratory tract. Infants too young to be fully vaccinated are at the highest risk of severe pertussis disease, hospitalization, and death. Vaccinating pregnant women against pertussis with a Tdap vaccine is recommended in more than 40 countries as a safe and effective strategy to protect infants for the first months of life. What is new? This review summarizes recent literature describing the burden of pertussis disease in infants worldwide prior to the introduction of maternal vaccination programs; pertussis disease incidence rates in infants aged <2-3 months were substantial in all countries with available data, exceeding 1000 cases per 100,000 population during outbreaks. Immunization of pregnant women with a Tdap vaccine can prevent about 70-90% of pertussis disease and up to 90.5% of pertussis hospitalizations in infants under 3 months of age. What is the impact? Limited available data suggest that incidence rates of pertussis disease after the introduction of Tdap maternal immunization have declined in infants. Current knowledge supports the implementation of Tdap maternal immunization programs.

Spatio-temporal analysis of Pertussis using geographic information system among Iranian population during 2012-2018

Background: In spite of existing vaccination programs in many countries, outbreaks of pertussis are still reported. In Iran, the suspected and confirmed cases of pertussis are reported annually. Due to the lack of similar studies, the purpose of the current study was to determine the Spatio-temporal distribution of Pertussis using Geographic Information System (GIS) to identify high-risk areas in Iran during 2012-2018.

Methods: In the current cross-sectional study, registered data in the department of vaccine-preventable diseases in the Iranian ministry of health were used. To assess the temporal trend, the Cochran–Armitage test was used. To show the spatial distribution and to identify hotspot areas, Choropleth map and Getis-Ord Gi statistics were used. All analyses performed by Arc.map10.5, Stata 15 and Excel 2010.

Results: The incidence of suspect pertussis cases had an increasing trend but did not have a linear trend (p=0.06). Most of the cases happened in under 1 year infants (62.66%). The incidence of reported cases in northern areas was higher than in the Southern areas. The Zanjan had the most reported cases during the understudied period with a median of 7.63 reported cases per 100,000. The clustering of infection and hotspots were identified in northern areas of Iran including Qazvin, Qom, Markazi, and Hamadan.

Conclusion: Our results showed that the cumulative incidence of reported cases is increasing. The northern provinces had the highest incidence of Pertussis. Therefore, the causes of this spatio-temporal pattern of pertussis should be determined. Also, supervision on vaccination programs in high-risk areas is recommended.

Genomic epidemiology of Iranian Bordetella pertussis: 50 years after the implementation of whole cell vaccine

Pertussis caused by Bordetella pertussis, remains a public health problem worldwide, despite high vaccine coverage in infants and children in many countries. Iran has been using whole cell vaccine for the last 50 years with more than 95% vaccination rate since 1988 and has experienced pertussis resurgence in recent years. Here, we sequenced 55 B. pertussis isolates mostly collected from three provinces with the highest number of pertussis cases in Iran, including Tehran, Mazandaran, and Eastern-Azarbayjan from the period of 2008-2016. Most isolates carried ptxP3/prn2 alleles (42/55, 76%), the same genotype as isolates circulating in acellular vaccine-administrating countries. The second most frequent genotype was ptxP3/prn9 (8/55, 14%). Only three isolates (5%) were ptxP1. Phylogenetic analysis showed that Iranian ptxP3 isolates can be divided into eight clades (Clades 1-8) with no temporal association. Most of the isolates from Tehran grouped together as one distinctive clade (Clade 8) with six unique single nucleotide polymorphisms (SNPs). In addition, the prn9 isolates were grouped together as Clade 5 with 12 clade-supporting SNPs. No pertactin deficient isolates were found among the 55 Iranian isolates. Our findings suggest that there is an ongoing adaptation and evolution of B. pertussis regardless of the types of vaccine used.

Comparison of anti-pertussis toxin ELISA and agglutination assays to assess immune responses to pertussis

BACKGROUND

The goal of our study was to compare the following two methods of assessment of pertussis post-vaccination immunity: bacterial agglutination test and pertussis toxin enzyme-linked immunosorbent assay (ELISA).

METHODS

The study was carried out in Perm Region, Russia. We measured pertussis immunity using two serological methods: ELISA of IgG to pertussis toxin (PT) and the agglutination test (AT) among 135 children, in the age range from 2 months to 17 years old. The immunization schedule included four doses of DTwP: at 3, 4.5 and 6 months of age and a booster at 18 months. All participants were divided into six age groups.

RESULTS

The percentage of samples with IgG level less than the detection limit in vaccinated children was 52.2%. The total seropositivity rate (the percent of children with agglutinin titres ≥1:160) in vaccinated children was 47.8%. Only a weak association was observed between agglutinin and anti-PT IgG titres (R = .3). Neither the primary nor the booster vaccination with DTwP influenced the IgG levels in children. Agglutinin titres significantly increased after vaccination and declined 5 years after the booster dose. Significant growth of IgG concentration was observed in 11-year-olds, indicating the presence of B. pertussis circulation in the childhood population.

CONCLUSIONS

Based on the obtained results and the results of other authors, we summarize that anti-PT ELISA should be carefully used to assess the population immunity to pertussis. Currently, there is neither a serological test that accurately determines the protection against pertussis nor a distinctive criterion of protection that can be applied in seroepidemiological studies.

Clinical and laboratory features of pertussis in hospitalized infants with confirmed versus probable pertussis cases

BACKGROUND

The clinical presentations of pertussis infection have considerable variation. Many infections and illnesses can cause prolonged repetitive paroxysmal cough that could be confused with Bordetella pertussis infection.

AIM

This retrospective study was designed to compare the clinico-laboratory findings between two groups of hospitalized infants with confirmed, and those who have clinical pertussis disease; to identify the possible additional diagnostic clues "for the diagnosis of confirmed pertussis disease".

SUBJECTS AND METHODS

The study population consisted of infants ≤12 months of age with clinical diagnosis of pertussis that fulfilled the World Health Organization definition for pertussis or those diagnosed by physicians. Clinico-laboratory findings were compared between two groups of patients (confirmed vs. clinical cases).

RESULTS

From a total of 118 infants admitted with a clinical diagnosis of pertussis, 16% (19/118) were confirmed by laboratory to have confirmed pertussis. Twelve of 19 (63%) and 71.99% of confirmed and clinical cases were younger than 6 months of age, respectively. For most patients, the duration of symptoms before hospitalization was <14 days. There were no significant differences between two groups of patients for paroxysmal cough and facial discoloration. However, whoop and apnea were more common among confirmed pertussis cases: P = 0.01, and P = 0.02, respectively. Leukocytosis (≥16,000/ml) (P = 0.01) and lymphocytosis (≥11,000) (P = 0.02) were reported significantly more frequently in confirmed pertussis cases.

CONCLUSION

Given the unavailability of a highly sensitive diagnostic test, in every afebrile patient with paroxysmal cough lasting for ≥7 days associated with whoop and/or apnea, particularly if accompanied by leukocytosis/lymphocytosis, pertussis disease should be considered. In this situation, prompt administration of empiric treatment for cases, and providing control measures to prevent infection transmission to contacts are recommended.