Diphtheria in the WHO European Region, 2010 to 2019

Respiratory Diphtheria in a 16-Year-Old Who Developed Multiple Life-Threatening Complications

Diphtheria is a contagious disease with high mortality. Although the global prevalence has been decreasing, the immigration of certain populations with suboptimal vaccination coverage has contributed to its resurgence in developed countries. We report a 16-year-old Afghan male with acute respiratory distress and life-threatening complications, including fulminant myocarditis with cardiac arrhythmias and neurologic complications. This case highlights the significance of optimal vaccination coverage, especially the vaccination status of migrants. This paper serves as a reminder of diphtheria's systemic impact and underscores the need for a multidisciplinary approach to respiratory diphtheria management. Vigilant monitoring, prompt immunoglobulin and antibiotic administration, and supportive care all play pivotal roles in enhancing patient outcomes and reducing mortality risks.

The trend in national childhood immunization program coverage throughout Serbian communities in Kosovo and Metohija from 2003 to 2022: pre-COVID-19 period vs. COVID-19 pandemic

BACKGROUND

The childhood immunization coverage in Serbian communities in Kosovo after the 1999 armed conflict has not been investigated. The study purpose was to evaluate the trend of immunization coverage with vaccines from the national childhood immunization program in Serbian communities in Kosovo and Metohija from 2003 to 2022.

METHODS

Data were retrieved from the annual reports of the Public Health Institute of Kosovska Mitrovica received through notifications from the primary health centers where vaccines are being administered. Data were analyzed using the linear regression and join-point regression models.

RESULTS

In the examined period, a significant decrease in vaccination coverage was observed for the following diseases: diphtheria, tetanus and pertussis (DTP), polio, as well as measles, mumps and rubella vaccines (MMR), then, the first revaccination for DTP and polio, the second revaccination against diphtheria and tetanus for children (DT) and polio, and the third revaccination against diphtheria and tetanus for adults (dT), as well as the second dose of the MMR vaccine. During the COVID-19 pandemic, a significant decrease in coverage was observed for primary vaccination against: DTP, polio and hepatitis B, first and second doses of the MMR vaccine, as well as the first and second revaccination for DTP and polio, and the third revaccination for dT.

CONCLUSION

A decline in coverage with DTP, MMR, polio and hepatitis B vaccines was observed between 2003 and 2022. This was even more pronounced during the COVID-19 pandemic. Further research on individual-level factors contributing to lower vaccination coverage is warranted.

Infection by a multidrug-resistant Corynebacterium diphtheriae strain: prediction of virulence factors, CRISPR-Cas system analysis, and structural implications of mutations conferring rifampin resistance

Cases of diphtheria, even in immunized individuals, are still reported in several parts of the world, including in Brazil. New outbreaks occur in Europe and other continents. In this context, studies on Corynebacterium diphtheriae infections are highly relevant, both for a better understanding of the pathogenesis of the disease and for controlling the circulation of clones and antimicrobial resistance genes. Here we present a case of cutaneous infection by multidrug-resistant Corynebacterium diphtheriae and provide its whole-genome sequencing. Genomic analysis revealed resistance genes, including tet(W), sul1, cmx, rpoB2, rbpA and mutation in rpoB. We performed phylogenetic analyzes and used the BRIG to compare the predicted resistance genes with those found in genomes from other significant isolates, including those associated with some outbreaks. Virulence factors such as spaD, srtBC, spaH, srtDE, surface-anchored pilus proteins (sapD), nonfimbrial adhesins (DIP0733, DIP1281, and DIP1621), embC and mptC (putatively involved in CdiLAM), sigA, dtxR and MdbA (putatively involved) in post-translational modification, were detected. We identified the CRISPR-Cas system in our isolate, which was classified as Type II-U based on the database and contains 15 spacers. This system functions as an adaptive immune mechanism. The strain was attributed to a new sequence type ST-928, and phylogenetic analysis confirmed that it was related to ST-634 of C. diphtheriae strains isolated in French Guiana and Brazil. In addition, since infections are not always reported, studies with the sequence data might be a way to complement and inform C. diphtheriae surveillance.

Balto and Togo during the cold winter of Alaska (1925): the two canine heroes in the fight against diphtheria

In recent years, diphtheria has re-emerged in areas with inadequate vaccination coverage, and Europe has not been spared with several cases among migrants. Diphtheria is a potentially fatal infection caused mainly by toxigenic strains of Corynebacterium diphtheriae. Due to the high mortality rate, especially among young children, the fight against diphtheria is considered one of the first conquests of immunization. In the history of medicine, there is a unique case of an unconventional response to a diphtheria outbreak in which sled dogs were used to overcome the supply difficulties of diphtheria antitoxin. The mass media followed the medical response to the outbreak and raised audience awareness of public health issues. The facts of Nome, Alaska, in 1925 can serve as a catalyst to rethink conventional responses to diphtheria outbreaks in low-income countries today and promote mass media awareness of public health importance.

Assessing the impact of booster vaccination on diphtheria transmission: Mathematical modeling and risk zone mapping

The COVID-19 pandemic caused significant disruptions in the healthcare system, affecting vaccinations and the management of diphtheria cases. As a consequence of these disruptions, numerous countries have experienced a resurgence or an increase in diphtheria cases. West Java province in Indonesia is identified as one of the high-risk areas for diphtheria, experiencing an upward trend in cases from 2021 to 2023. To analyze the situation, we developed an SIR model, which integrated DPT and booster vaccinations to determine the basic reproduction number, an essential parameter for infectious diseases. Through spatial analysis of geo-referenced data, we identified hotspots and explained diffusion in diphtheria case clusters. The calculation of R0 resulted in an R0 = 1.17, indicating the potential for a diphtheria outbreak in West Java. To control the increasing cases, one possible approach is to raise the booster vaccination coverage from the current 64.84% to 75.15%, as suggested by simulation results. Furthermore, the spatial analysis revealed that hot spot clusters were present in the western, central, and southern regions, posing a high risk not only in densely populated areas but also in rural regions. The diffusion pattern of diphtheria clusters displayed an expansion-contagious pattern. Understanding the rising trend of diphtheria cases and their geographic distribution can offer crucial insights for government and health authorities to manage the number of diphtheria cases and make informed decisions regarding the best prevention and intervention strategies.

Imported Toxigenic Corynebacterium Diphtheriae in Refugees with Polymicrobial Skin Infections, Germany, 2022

During August-December 2022, toxigenic Corynebacterium diphtheriae was isolated from 25 refugees with skin infections and 2 refugees with asymptomatic throat colonization at a refugee reception center in Germany. None had systemic toxin-mediated illness. Of erosive/ulcerative skin infections, 96% were polymicrobial. Erosive/ulcerative wounds in refugees should undergo testing to rule out cutaneous diphtheria.

Multiplexed bead-based assay for the simultaneous quantification of human serum IgG antibodies to tetanus, diphtheria, pertussis toxin, filamentous hemagglutinin, and pertactin

Background

Luminex bead-based assays offer multiplexing to test antibodies against multiple antigens simultaneously; however, this requires validation using internationally certified reference standards. Therefore, there is an urgent need to characterize existing reference standards for the standardization of multiplex immunoassays (MIAs). Here, we report the development and validation of an MIA for the simultaneous estimation of levels of human serum immunoglobulin G (IgG) antibodies for pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), diphtheria toxoid (DT), and tetanus toxoid (TT).

Methods

The MIA was assessed using a panel of human serum samples and WHO reference standards. The WHO reference standards were also studied for suitability in the MIA. Purified antigens (PT, FHA, PRN, DT, and TT) were coupled to the spectrally unique magnetic carboxylated microspheres. The method was validated in accordance with the United States Food and Drug Administration (US FDA), European Medicines Agency (EMA), and the International Committee of Harmonization Multidisciplinary (ICH M10) guidelines, and parameters such as precision, accuracy, dilutional linearity, assay range, robustness, and stability were assessed. Method agreements with commercially available IgG enzyme-linked immunosorbent assay (ELISA) assays were also evaluated. In addition, the study assessed the level of correlation between the IgG levels estimated by the MIA and the cell-based neutralizing antibody assays for PT and DT.

Results

We identified that an equimix of WHO international standards (i.e., 06/142, 10/262, and TE-3) afforded the best dynamic range for all the antigens in the MIA. For all five antigens, we observed that the back-fitted recoveries using the four-parameter logistic (4-PL) regression fits ranged between 80% and 120% for all calibration levels, and the percentage coefficient of variation (% CV) was < 20%. In addition, the difference in mean fluorescence intensity (MFI) between the monoplex and multiplex format was < 10% for each antigen, indicating no crosstalk among the beads. The MIA also showed good agreement with conventional and commercially available assays, and a positive correlation (> 0.75) with toxin neutralization assays for PT and DT was observed.

Conclusion

The MIA that was calibrated in accordance with WHO reference standards demonstrated increased sensitivity, reproducibility, and high throughput capabilities, allowing for the design of robust studies that evaluate both natural and vaccine-induced immunity.

Review of scientific evidence to support recommendations of the full-dose DTaP-IPV vaccination in pre-school age children in Italy

INTRODUCTION

Two vaccine formulations are available to prevent diphtheria, tetanus, pertussis, and poliomyelitis: the pediatric full-dose (DTaP-IPV) and the reduced dose formulation (dTap-IPV). Different immunization schedules are internationally recommended for the pre-school booster dose.

AREAS COVERED

International and Italian recommendations, scientific evidence on immunogenicity and safety of DTaP/dTap vaccines to support the full dose as a pre-school booster and Italian vaccination coverage (VC) up to adolescence.

EXPERT OPINION

The WHO recommends a '3+1' schedule with DTaP vaccine for primary immunization, followed by a pre-school booster with DTaP or dTap vaccine. In Italy, a '2+1' schedule, with no booster in the second year, and a pre-school booster dose are recommended with DTPa-IPV vaccines. Studies showed a non-inferior immunogenicity in dTap vaccinees in pre-school age; nevertheless, the antibody titers were usually greater in children vaccinated with DTaP, while lower frequencies of adverse events were recorded in children receiving dTap. Italian VCs for pre-school and adolescent boosters have not been satisfactory, which further reduced during the COVID-19 period. In Italy, the pre-school booster offers the last chance to receive a full dose of DTaP vaccine, thus, representing the most suitable intervention to provide lasting protection in children.