Epidemic diphtheria in the Newly Independent States of the Former Soviet Union: implications for diphtheria control in the United States

The evaluation of anti-diphtheria toxoid antibodies in healthy population in Kon Tum, Vietnam: a population-based study

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The risk of diphtheria remains high in Kon Tum given the low seroprevalence.

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One third of community in Kon Tum have no protective antibodies to diphtheria.

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The antibodies from previous childhood vaccination gradually wane over time.

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A booster dose (5-7 years) is recommended for adolescents and adults in Vietnam.

Background

Despite diphtheria immunization are to apply an effective primary immunization in childhood and to maintain immunity throughout life. Cases of diphtheria have been reported in Viet Nam in recent years. The aim of this study was to evaluate the seroprevalence of IgG antibodies to diphtheria toxoid among healthy person population in Kon Tum, Viet Nam.

Methods

Blood samples were obtained from 2225 healthy persons aged 2-98 years collected in 2019 and 2020. Samples were tested for diphtheria toxoid antibodies by commercial Anti-Diphtheria Toxoid IgG Enzyme-Linked Immunosorbent Assay (ELISA).

Results

An antibody level of <0.01 IU/mL (susceptibility) was found in 802 (36.0%) of the 2225 subjects, 136 (6.1%) had antibody levels of 0.01–0.099 IU/mL (basic protection), and 1287 (57.8%) had antibody levels ≥0.1 IU/mL (full protection). The full protection level increased significantly in persons aged above 60 years with antibody levels of 70.6%. No significant difference in seroprotection prevalence was found according to gender, ethnicity, residence, education and occupation. The results also demonstrated that people with vaccination against diphtheria during past 10 years were found to have a high immunity (83.8%) compared to 54.8% (OR: 4.7; 95%CI: 3.8-6.5) and 60.7% (OR: 3.8; 95%CI: 2.6-5.7) in persons with no and unknown vaccination (p <0.0001).

Conclusions

The level of anti-diphtheria toxoid antibodies among children and adults in Kon Tum was low. The high risk of diphtheria outbreaks may occur among individuals lacking basic immunity against diphtheria.

A patient with respiratory toxigenic diphtheria in Greece after more than 30 years

The introduction of treatment and systematic vaccination has significantly reduced diphtheria mortality; however, toxigenic strains continue to circulate worldwide. The emergence of an indigenous diphtheria case with fatal outcome in Greece, after 30 years, raised challenges for laboratory confirmation, clinical and public health management. Toxigenic Corynebacterium diphtheriae was isolated from an incompletely vaccinated 8-year-old boy with underlying conditions. The child passed away due to respiratory distress syndrome, before the administration of diphtheria antitoxin (DAT). All close contacts in family, school and hospital settings were investigated. Pharyngeal swabs were obtained to determine asymptomatic carriage. Chemoprophylaxis was given for 7 days to all close contacts and a booster dose to those incompletely vaccinated. Testing revealed a classmate, belonging to a subpopulation group (Roma), and incompletely vaccinated, as an asymptomatic carrier with an indistinguishable toxigenic strain (same novel multilocus sequence type, designated ST698). This case highlights the role of asymptomatic carriage, as the entry of toxigenic strains into susceptible populations can put individuals and their environment at risk. Maintenance of high-level epidemiological and microbiological surveillance, implementation of systematic vaccination in children and adults with primary and booster doses, availability of a DAT stockpile, and allowing timely administration are the cornerstone to prevent similar incidents in the future.

Global Epidemiology of Diphtheria, 2000-20171

In 2017, a total of 8,819 cases of diphtheria were reported worldwide, the most since 2004. However, recent diphtheria epidemiology has not been well described. We analyzed incidence data and data from the literature to describe diphtheria epidemiology. World Health Organization surveillance data were 81% complete; completeness varied by region, indicating underreporting. As national diphtheria–tetanus–pertussis (DTP) 3 coverage increased, the proportion of case-patients <15 years of age decreased, indicating increased protection of young children. In countries with higher case counts, 66% of case-patients were unvaccinated and 63% were <15 years of age. In countries with sporadic cases, 32% of case-patients were unvaccinated and 66% were >15 years of age, consistent with waning vaccine immunity. Global DTP3 coverage is suboptimal. Attaining high DTP3 coverage and implementing recommended booster doses are necessary to decrease diphtheria incidence. Collection and use of data on subnational and booster dose coverage, enhanced laboratory capacity, and case-based surveillance would improve data quality.

Diphtheria or Streptococcal Pharyngitis: A Case Report Highlighting the Diagnostic Dilemma in the Post-vaccination Era

Diphtheria is an acute, highly infectious, toxigenic, and vaccine-preventable disease that commonly affects children under 12 years of age. The incidences of diphtheria have significantly dropped due to vaccination with diphtheria, pertussis, tetani (DPT). Recently, there is an increasing trend in reports of diphtheria throughout the world and specifically from developing countries. According to a World Health Organization (WHO) report, more than 80% of the global diphtheria cases in the post-vaccination era were from India and Indonesia. This could probably be signaling its re-emergence, which may be attributed to several factors that include incomplete immunization. Pharyngitis caused by group A Streptococcus is most frequently seen in children and can be clinically similar in presentation to diphtheria. We share our experience of managing a case of an eight-year-old child, who was clinically suspected to be suffering from diphtheria.

Improving immunization strategies in patients with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) are susceptible to varieties of opportunistic infections due to immunological changes in the setting of their disease and drug-induced immunosuppression. Even though numerous infections can be prevented by vaccine, vaccination in IBD patients is inadequate. Data showed only 9% were vaccinated against pneumococcal infection and 28% described commonly receiving influenza vaccine. This review article discusses the recent immunizations against influenza virus; pneumococcal infection; human papilloma virus; tetanus, diphtheria and pertussis; measles, mumps and rubella; varicella zoster; and herpes zoster for individuals diagnosed with IBD and those patients with drug-related immunosuppression. In addition, this review discusses concerns about IBD patients planning to travel abroad. Immunization status and screening for opportunistic infection need to be addressed in IBD patients at the time of diagnosis and they should be vaccinated accordingly. Generally, standard vaccination strategies should be pursued in IBD patients, although live vaccines should be avoided while they are not immunocompetent.

Severe diphtheria with neurologic and myocardial involvement in a Swedish patient: a case report

Background

Diphtheria is caused by Corynebacterium diphtheriae. Although waning in incidence diphtheria can cause severe disease as in this rare Swedish case with several complications.

Case presentation

A 55-year old male presented to the emergency room with severe respiratory symptoms and greyish membranes in the airways, which turned positive for C. diphtheriae. He was put on ventilator support and remained hospitalized for three months. During care he developed myocarditis and severe neurological disease and he was also co-infected with tuberculosis. The patient was discharged with a favorable outcome.

Conclusions

Diphtheria should be suspected in patients with life-threatening pneumonia especially if the patient has a history of travelling. Our patient was not treated with diphtheria anti-toxin (DAT) which may have contributed to the severity of the disease.

Durability of Vaccine-Induced Immunity Against Tetanus and Diphtheria Toxins: A Cross-sectional Analysis

BACKGROUND

Many adult immunization schedules recommend that tetanus and diphtheria vaccination be performed every 10 years. In light of current epidemiological trends of disease incidence and rates of vaccine-associated adverse events, the 10-year revaccination schedule has come into question.

METHODS

We performed cross-sectional analysis of serum antibody titers in 546 adult subjects stratified by age or sex. All serological results were converted to international units after calibration with international serum standards.

RESULTS

Approximately 97% of the population was seropositive to tetanus and diphtheria as defined by a protective serum antibody titer of ≥0.01 IU/mL. Mean antibody titers were 3.6 and 0.35 IU/mL against tetanus and diphtheria, respectively. Antibody responses to tetanus declined with an estimated half-life of 14 years (95% confidence interval, 11-17 years), whereas antibody responses to diphtheria were more long-lived and declined with an estimated half-life of 27 years (18-51 years). Mathematical models combining antibody magnitude and duration predict that 95% of the population will remain protected against tetanus and diphtheria for ≥30 years without requiring further booster vaccination.

CONCLUSIONS

These studies demonstrate that durable levels of protective antitoxin immunity exist in the majority of vaccinated individuals. Together, this suggests that it may no longer be necessary to administer booster vaccinations every 10 years and that the current adult vaccination schedule for tetanus and diphtheria should be revisited.

Mutated form (G52E) of inactive diphtheria toxin CRM197: molecular simulations clearly display effect of the mutation to NAD binding

Mutated form (G52E) of diphtheria toxin (DT) CRM197 is an inactive and nontoxic enzyme. Here, we provided a molecular insight using comparative molecular dynamics (MD) simulations to clarify the influence of a single point mutation on overall protein and active-site loop. Post-processing MD analysis (i.e. stability, principal component analysis, hydrogen-bond occupancy, etc.) is carried out on both wild and mutated targets to investigate and to better understand the mechanistic differences of structural and dynamical properties on an atomic scale especially at nicotinamide adenine dinucleotide (NAD) binding site when a single mutation (G52E) happens at the DT. In addition, a docking simulation is performed for wild and mutated forms. The docking scoring analysis and docking poses results revealed that mutant form is not able to properly accommodate the NAD molecule.

A review of sentinel laboratory performance: identification and notification of bioterrorism agents

CONTEXT

The anthrax incident of 2001 in the United States prompted the College of American Pathologists (CAP), the Association of Public Health Laboratories, and the Centers for Disease Control and Prevention to develop exercises for Laboratory Response Network (LRN) sentinel laboratories.

OBJECTIVE

To provide an overview of the results of the CAP bioterrorism Laboratory Preparedness Survey (LPS, 2007) and Laboratory Preparedness Exercise (LPX, 2008) and assist LRN sentinel laboratories and public health agencies in planning for bioterrorism events.

DESIGN

Bioterrorism agents and nonbiothreat mimic organisms were provided in 2 mailings per year (2007 and 2008, 20 total challenges). Within each mailing, 2 to 3 agents were category A or category B bioterrorism agents (total of 10 categoric challenges). Some category A/B isolates were modified/vaccine strains. The total number of laboratories participating in these exercises ranged from 1316 to 1381. Isolate characteristics used to identify the organisms were compiled along with the participants' reporting actions. Educational commentary was provided with each exercise.

RESULTS

Acceptable identification responses were as follows: Bacillus anthracis, 90% (2007) and 99.9% (2008); Yersinia pestis, 83.8% (2007) and 87.6% (2008); and Francisella tularensis subsp Holarctica, 86.6% (2007) and 91.6% (2008). The time interval between specimen receipt and notification of results to an LRN reference laboratory decreased from more than 10 days in 2007 to 3 or 4 days in 2008 for some challenges.

CONCLUSIONS

The bioterrorism challenge program (LPS, LPX) provides important comparative data from more than 1300 sentinel laboratories that can be used by individual laboratories to evaluate their identification and LRN reporting performance.

Quo vadis SANEPID? A cross-country analysis of public health reforms in 10 post-Soviet states

BACKGROUND

The public health systems of the post-Soviet states have evolved from the san-epid system, which dominated public health practice throughout the former Soviet Union. Since independence, reforms have taken different directions. This article provides a cross-country comparison of public health reform processes and contents in 10 post-Soviet states.

METHODS

The study is descriptive and comparative, based on a literature review of the major health databases, the Health Systems in Transition (HiT) volumes and grey literature. Search terms included terms on public health, the san-epid services and organizational reforms in one or several post-Soviet states.

RESULTS

Public health reforms have varied greatly: some countries have preserved the san-epid structure, some have built structures in addition to the san-epid system, and others have set up a new public health infrastructure. Traditional "functions" of the former san-epid system, such as vaccination, are still more advanced, while health promotion and intersectoral collaboration are less developed.

CONCLUSION

Critical self-evaluation, implementation of performance measurement and rigorous external research will prove essential in identifying strengths and weaknesses of past reforms and learning for the future.

Diphtheria boosters for adults: Balancing risks

Combined tetanus-diphtheria vaccines are now the only means of protecting adults from tetanus or diphtheria. When advising on the benefits and risk of vaccinating for one disease, clinicians now have to consider the other vaccine component, and questions have arisen about where the balance of risk lies for different patients. Five doses of diphtheria-toxoid containing vaccine are probably sufficient protection for individuals who remain in low-incidence countries such as those in most of Western Europe. Adults who remain in the UK are extremely unlikely to be exposed to diphtheria and this needs to be taken into account when assessing the balance of risk where individuals have received fewer than five doses of diphtheria toxoid but five or more doses of tetanus toxoid. In contrast to diphtheria, if someone has received fewer than five doses of tetanus toxoid but is up to date for diphtheria toxoid, the balance of lifelong risk is probably in favour of giving tetanus toxoid irrespective of the individual's diphtheria status. For travellers to diphtheria endemic countries boosters are recommended if more than 10 years has elapsed since the last dose. For individuals who have already received five or more doses of tetanus vaccine in the past, receiving further boosters of tetanus in combination with diphtheria toxoid is unlikely to cause any significant reactions. The only absolute contraindication to such boosters is a previously documented anaphylactic reaction to either diphtheria or tetanus toxoid. Individuals who have a history of such a reaction should be well advised regarding probable risk of infection, symptoms of the disease and the need to seek early treatment.

Bacteriophage-based vectors for site-specific insertion of DNA in the chromosome of Corynebacteria

In Corynebacterium diphtheriae, diphtheria toxin is encoded by the tox gene of some temperate corynephages such as beta. beta-like corynephages are capable of inserting into the C. diphtheriae chromosome at two specific sites, attB1 and attB2. Transcription of the phage-encoded tox gene, and many chromosomally encoded genes, is regulated by the DtxR protein in response to Fe(2+) levels. Characterizing DtxR-dependent gene regulation is pivotal in understanding diphtheria pathogenesis and mechanisms of iron-dependent gene expression; although this has been hampered by a lack of molecular genetic tools in C. diphtheriae and related Coryneform species. To expand the systems for genetic manipulation of C. diphtheriae, we constructed plasmid vectors capable of integrating into the chromosome. These plasmids contain the beta-encoded attP site and the DIP0182 integrase gene of C. diphtheriae NCTC13129. When these vectors were delivered to the cytoplasm of non-lysogenic C. diphtheriae, they integrated into either the attB1 or attB2 sites with comparable frequency. Lysogens were also transformed with these vectors, by virtue of the second attB site. An integrated vector carrying an intact dtxR gene complemented the mutant phenotypes of a C. diphtheriae DeltadtxR strain. Additionally, strains of beta-susceptible C. ulcerans, and C. glutamicum, a species non-permissive for beta, were each transformed with these vectors. This work significantly extends the tools available for targeted transformation of both pathogenic and non-pathogenic Corynebacterium species.

Susceptibility to diphtheria in adults: prevalence and relationship to gender and social variables

Recent outbreaks of diphtheria have drawn attention to the re-emergence of this disease. This study investigated susceptibility to diphtheria in north-east Germany and its relationship to gender and social factors. A study population of 4275 individuals recruited for the population-based Study of Health in Pomerania (SHIP) was available for analysis. IgG antibodies against diphtheria toxin were determined by ELISA and were used to define susceptibility to diphtheria (i.e., IgG titres < 0.1 IU/mL). The prevalence of susceptibility to diphtheria was 32.4%. Multivariate analysis revealed 45% increased odds of women being susceptible to diphtheria. Women who had not received diphtheria toxoid vaccination during the previous 10 years had four-fold increased odds of being susceptible to diphtheria toxin compared with unvaccinated men. None of the social factors investigated was associated with susceptibility status. It was concluded that a high proportion of middle-aged adults was susceptible to diphtheria. Women lacked seroprotection more often than men, which might be explained, in part, by gender-specific immune responses following vaccination. There is a need for information campaigns to improve public awareness of these problems.

Immunizations for international travel

Many infections encountered by international travelers can be prevented by adherence to personal protective measures and appropriate vaccinations. This review outlined the incidence and importance of the major vaccine-preventable infectious diseases encountered by U.S. travelers, as well as the indications, contraindications, and side effects of available vaccines. Official proof of yellow fever vaccine often is required for entry into some countries. Based on endemic or epidemic infections at destinations, planned activities, and age and medical history of international travelers, other vaccines may be recommended. Many clinicians will be familiar with some of the infections and vaccines that may be used in travelers; other vaccines may be encountered infrequently and associated with significant risk of adverse effects. Since vaccines do not provide complete protection and some travel-related infections do not have vaccines available yet (e.g., malaria and dengue fever), physicians need to be vigilant concerning febrile illness in returning travelers.