Diphtheria in the Russian Federation in the 1990s

MA, Tovar-Rosero YY, Oñate AA, O'Ryan M. Two centuries of vaccination: historical and conceptual approach and future perspectives

Over the past two centuries, vaccines have been critical for the prevention of infectious diseases and are considered milestones in the medical and public health history. The World Health Organization estimates that vaccination currently prevents approximately 3.5-5 million deaths annually, attributed to diseases such as diphtheria, tetanus, pertussis, influenza, and measles. Vaccination has been instrumental in eradicating important pathogens, including the smallpox virus and wild poliovirus types 2 and 3. This narrative review offers a detailed journey through the history and advancements in vaccinology, tailored for healthcare workers. It traces pivotal milestones, beginning with the variolation practices in the early 17th century, the development of the first smallpox vaccine, and the continuous evolution and innovation in vaccine development up to the present day. We also briefly review immunological principles underlying vaccination, as well as the main vaccine types, with a special mention of the recently introduced mRNA vaccine technology. Additionally, we discuss the broad benefits of vaccines, including their role in reducing morbidity and mortality, and in fostering socioeconomic development in communities. Finally, we address the issue of vaccine hesitancy and discuss effective strategies to promote vaccine acceptance. Research, collaboration, and the widespread acceptance and use of vaccines are imperative for the continued success of vaccination programs in controlling and ultimately eradicating infectious diseases.

Surveillance of diphtheria in the Netherlands between 2000-2021: cutaneous diphtheria supersedes the respiratory form

BACKGROUND

Diphtheria is a severe respiratory or cutaneous infectious disease, caused by exotoxin producing Corynebacterium diphtheriae, C. ulcerans and C. pseudotuberculosis. Diphtheria is once again prevalent due to breakdown of immunisation programmes, social disruption and unrest.

AIM

This study describes the notified diphtheria cases in the Netherlands between 2000-2021 and isolates that were sent to the National Institute for Public Health and the Environment (RIVM).

METHODS

File investigation was performed including all notified cases and isolates of C. diphtheriae, C. ulcerans and C. pseudotuberculosis that were tested for toxin production using a toxin-PCR and Elek test. An exploratory review was performed to understand transmission in populations with a high vaccination uptake.

RESULTS

Eighteen diphtheria notifications were made with confirmed toxigenic C. diphtheriae (n = 9) or ulcerans (n = 9) between 2000 and 2021. Seventeen (94.4%) presented with a cutaneous infection. All cases with a suspected source abroad (n = 8) concerned infection with C. diphtheriae. In contrast, 9/10 cases infected in the Netherlands were caused by C. ulcerans, a zoonosis. Secondary transmission was not reported. Isolates of C. ulcerans sent to the RIVM produced more often the diphtheria exotoxin (11/31; 35%) than C. diphtheriae (7/89; 7.9%).

CONCLUSION

Both human-to-human transmission of C. diphtheriae and animal-to-human transmission of C. ulcerans rarely occurs in the Netherlands. Cases mainly present with a cutaneous infection. Travel-related cases remain a risk for transmission to populations with low vaccination coverage, highlighting the importance of immunization and diphtheria control measures.

Diphtheria in Pakistan post-COVID-19, a potential public health threat: an update

Diphtheria, a vaccine-preventable disease, remains a concern in Pakistan as cases have risen post-COVID-19 pandemic causing more than 45 deaths in Pakistan in the year 2022. The respiratory variant of the disease is more common and can lead to serious complications, such as myocarditis and respiratory insufficiency. Diphtheria has caused havoc in the past killing millions of people worldwide before the development of its vaccine. Although the diphtheria toxoid vaccine is effective against toxigenic strains, there have been cases of treatment-resistant strains, particularly the non-toxigenic strains of C. diphtheriae. Pakistan's economic and health systems have suffered setbacks, which have been exacerbated by the COVID-19 pandemic. The pandemic has disrupted routine vaccination programs, and recent floods have contributed to an increase in diphtheria cases and rendered millions homeless. Poor immunization services, inadequate training of vaccination teams, and wealth inequality have all contributed to unequal vaccination coverage in Pakistan. The rising cases of diphtheria call for prompt action, including booster shots, updating vaccination records and administering immediate doses of the toxoid to close contacts.

Impact of Routine Childhood Immunization in Reducing Vaccine-Preventable Diseases in the United States

BACKGROUND AND OBJECTIVES

Current routine immunizations for children aged ≤10 years in the United States in 2019 cover 14 vaccine-preventable diseases. We characterize the public-health impact of vaccination by providing updated estimates of disease incidence with and without universally recommended pediatric vaccines.

METHODS

Prevaccine disease incidence was obtained from published data or calculated using annual case estimates from the prevaccine period and United States population estimates during the same period. Vaccine-era incidence was calculated as the average incidence over the most recent 5 years of available surveillance data or obtained from published estimates (if surveillance data were not available). We adjusted for underreporting and calculated the percent reduction in overall and age-specific incidence for each disease. We multiplied prevaccine and vaccine-era incidence rates by 2019 United States population estimates to calculate annual number of cases averted by vaccination.

RESULTS

Routine immunization reduced the incidence of all targeted diseases, leading to reductions in incidence ranging from 17% (influenza) to 100% (diphtheria, Haemophilus influenzae type b, measles, mumps, polio, and rubella). For the 2019 United States population of 328 million people, these reductions equate to >24 million cases of vaccine-preventable disease averted. Vaccine-era disease incidence estimates remained highest for influenza (13 412 per 100 000) and Streptococcus pneumoniae-related acute otitis media (2756 per 100 000).

CONCLUSIONS

Routine childhood immunization in the United States continues to yield considerable sustained reductions in incidence across all targeted diseases. Efforts to maintain and improve vaccination coverage are necessary to continue experiencing low incidence levels of vaccine-preventable diseases.

Interactions between the Re-Emerging Pathogen Corynebacterium diphtheriae and Host Cells

Corynebacterium diphtheriae, the etiological agent of diphtheria, is a re-emerging pathogen, responsible for several thousand deaths per year. In addition to diphtheria, systemic infections, often by non-toxigenic strains, are increasingly observed. This indicates that besides the well-studied and highly potent diphtheria toxin, various other virulence factors may influence the progression of the infection. This review focuses on the known components of C. diphtheriae responsible for adhesion, invasion, inflammation, and cell death, as well as on the cellular signaling pathways activated upon infection.

Regional poverty and infection disease: early exploratory evidence from the COVID-19 pandemic

This paper examines the role of regional poverty on the COVID-19 pandemic in the USA. It also explores how the effects differ with the concentration of ethnic minorities. We find that poverty is a significant and consistent determinant of higher COVID-19 infections and fatalities. Prevalent poverty areas experienced higher infections due to economic structure that require hypermobility (high mobility and interpersonal interaction)-more physical human to human contact resulting in higher deaths from limited access to health services. These are also regions where minority groups are concentrated. Disproportionate infections and fatalities occurred within the black, Hispanic, and Asian population. Our evidence is robust to state fixed effects that capture local COVID-19 mitigation policies, multi-level hierarchical modeling, spatial autoregressive assessment, and large sets of county-level health, social, and economic factors. This paper contributes to the literature on health and economic disparities and their resulting consequences for infectious diseases.

How Do Economic Fluctuations Affect the Mortality of Infectious Diseases?

This paper uses the mixed frequency vector autoregression model to explore the impact of economic fluctuations on infectious diseases mortality (IDM) from China perspective. We find that quarterly gross domestic product (GDP) fluctuations have a negative impact on the annual IDM, indicating that the mortality of infectious diseases varies counter-cyclically with the business cycle in China. Specifically, IDM usually increases with deterioration in economic conditions, and vice versa. The empirical results are consistent with the hypothesis I derived from the theoretical analysis, which highlights that economic fluctuations can negatively affect the mortality of infectious diseases. The findings can offer revelations for the government to consider the role of economic conditions in controlling the epidemic of infectious diseases. Policymakers should adopt appropriate and effective strategies to mitigate the potential negative effects of macroeconomic downturns on the mortality of infectious diseases. In the context of the COVID-19 pandemic, these analyses further emphasize the importance of promoting economic growth, increasing public health expenditure, and preventing and controlling foreign infectious diseases.

Clinical and Epidemiological Aspects of Diphtheria: A Systematic Review and Pooled Analysis

BACKGROUND

Diphtheria, once a major cause of childhood morbidity and mortality, all but disappeared following introduction of diphtheria vaccine. Recent outbreaks highlight the risk diphtheria poses when civil unrest interrupts vaccination and healthcare access. Lack of interest over the last century resulted in knowledge gaps about diphtheria's epidemiology, transmission, and control.

METHODS

We conducted 9 distinct systematic reviews on PubMed and Scopus (March-May 2018). We pooled and analyzed extracted data to fill in these key knowledge gaps.

RESULTS

We identified 6934 articles, reviewed 781 full texts, and included 266. From this, we estimate that the median incubation period is 1.4 days. On average, untreated cases are colonized for 18.5 days (95% credible interval [CrI], 17.7-19.4 days), and 95% clear Corynebacterium diphtheriae within 48 days (95% CrI, 46-51 days). Asymptomatic carriers cause 76% (95% confidence interval, 59%-87%) fewer cases over the course of infection than symptomatic cases. The basic reproductive number is 1.7-4.3. Receipt of 3 doses of diphtheria toxoid vaccine is 87% (95% CrI, 68%-97%) effective against symptomatic disease and reduces transmission by 60% (95% CrI, 51%-68%). Vaccinated individuals can become colonized and transmit; consequently, vaccination alone can only interrupt transmission in 28% of outbreak settings, making isolation and antibiotics essential. While antibiotics reduce the duration of infection, they must be paired with diphtheria antitoxin to limit morbidity.

CONCLUSIONS

Appropriate tools to confront diphtheria exist; however, accurate understanding of the unique characteristics is crucial and lifesaving treatments must be made widely available. This comprehensive update provides clinical and public health guidance for diphtheria-specific preparedness and response.

Whole Genome Sequencing for Surveillance of Diphtheria in Low Incidence Settings

Corynebacterium diphtheriae (C. diphtheriae) is a relatively rare pathogen in most Western countries. While toxin producing strains can cause pharyngeal diphtheria with potentially fatal outcomes, the more common presentation is wound infections. The diphtheria toxin is encoded on a prophage and can also be carried by Corynebacterium ulcerans and Corynebacterium pseudotuberculosis. Currently, across Europe, infections are mainly diagnosed in travelers and refugees from regions where diphtheria is more endemic, patients from urban areas with poor hygiene, and intravenous drug users. About half of the cases are non-toxin producing isolates. Rapid identification of the bacterial pathogen and toxin production is a critical element of patient and outbreak management. Beside the immediate clinical management of the patient, public health agencies should be informed of toxigenic C. diphtheriae diagnoses as soon as possible. The collection of case-related epidemiological data from the patient is often challenging due to language barriers and social circumstances. However, information on patient contacts, vaccine status and travel/refugee route, where appropriate, is critical, and should be documented. In addition, isolates should be characterized using high resolution typing, in order to identify transmissions and outbreaks. In recent years, whole genome sequencing (WGS) has become the gold standard of high-resolution typing methods, allowing detailed investigations of pathogen transmissions. De-centralized sequencing strategies with redundancy in sequencing capacities, followed by data exchange may be a valuable future option, especially since WGS becomes more available and portable. In this context, the sharing of sequence data, using public available platforms, is essential. A close interaction between microbiology laboratories, treating physicians, refugee centers, social workers, and public health officials is a key element in successful management of suspected outbreaks. Analyzing bacterial isolates at reference centers may further help to provide more specialized microbiological techniques and to standardize information, but this is also more time consuming during an outbreak. Centralized communication strategies between public health agencies and laboratories helps considerably in establishing and coordinating effective surveillance and infection control. We review the current literature on high-resolution typing of C. diphtheriae and share our own experience with the coordination of a Swiss-German outbreak.

Proteomics of diphtheria toxoid vaccines reveals multiple proteins that are immunogenic and may contribute to protection of humans against Corynebacterium diphtheriae

Introduced for mass immunization in the 1920s, vaccines against diphtheria are among the oldest and safest vaccines known. The basic principle of their production is the inactivation of purified diphtheria toxin by formaldehyde cross-linking, which converts the potentially fatal toxin in a completely harmless protein aggregate, which is still immunogenic. Since in addition to diphtheria toxin also other proteins may be secreted by Corynebacterium diphtheriae during cultivation, we assumed that diphtheria toxoid might not be the only component present in the vaccine. To address this question, we established a protocol to reverse formaldehyde cross-linking and carried out mass spectrometric analyses. Different secreted, membrane-associated and cytoplasmic proteins of C. diphtheriae were detected in several vaccine preparations from across the world. Based on these results, bioinformatics and Western blot analyses were applied to characterize if these proteins are immunogenic and may therefore support protection against C. diphtheriae. In frame of this study, we could show that the C. diphtheriae toxoid vaccines induce antibodies against different C. diphtheriae proteins and against diphtheria toxin secreted by Corynebacterium ulcerans, an emerging pathogen which is outnumbering C. diphtheriae as cause of diphtheria-like illness in Western Europe.

Austerity, measles and mandatory vaccination: cross-regional analysis of vaccination in Italy 2000-14

Background

Italy has experienced a resurgence in measles since 2015. Although much emphasis has been placed on the role of individuals opting out of vaccination, here we test the hypothesis that large budget reductions in public health spending were also a contributing factor.

Methods

Multi-variate statistical models were used to assess the relationship between measles, mumps and rubella (MMR) coverage and real public health expenditure per-capita across Italy's 20 regions covering the period 2000-14.

Results

Between 2010 and 2014 Italy's public health expenditure fell by over 2%, although varying among regions. Fixed effects models estimate that each 1% reduction in per-capita public health expenditure was associated with a decrease of 0.5 percentage points (95% CI: 0.36-0.65 percentage points) in MMR coverage, after adjusting for time and regional-specific time trends. The consequences can be illustrated by comparing two regions, Lazio, where public health spending fell by 5% and MMR coverage by over 3 percentage points, and Sardinia, a historically deprived region, where public health spending partly rose and MMR rates remained approximately steady.

Conclusion

Adoption of austerity policies in the Italian health system was found to be significantly associated with declining vaccination rates for MMR. However, the recent introduction of mandatory vaccination for Italian children may help counteract this trend.

Molecular Characterization of Corynebacterium diphtheriae Outbreak Isolates, South Africa, March-June 2015

In 2015, a cluster of respiratory diphtheria cases was reported from KwaZulu-Natal Province in South Africa. By using whole-genome analysis, we characterized 21 Corynebacterium diphtheriae isolates collected from 20 patients and contacts during the outbreak (1 patient was infected with 2 variants of C. diphtheriae). In addition, we included 1 cutaneous isolate, 2 endocarditis isolates, and 2 archived clinical isolates (ca. 1980) for comparison. Two novel lineages were identified, namely, toxigenic sequence type (ST) ST-378 (n = 17) and nontoxigenic ST-395 (n = 3). One archived isolate and the cutaneous isolate were ST-395, suggesting ongoing circulation of this lineage for >30 years. The absence of preexisting molecular sequence data limits drawing conclusions pertaining to the origin of these strains; however, these findings provide baseline genotypic data for future cases and outbreaks. Neither ST has been reported in any other country; this ST appears to be endemic only in South Africa.

Seroepidemiology: an underused tool for designing and monitoring vaccination programmes in low- and middle-income countries

Seroepidemiology, the use of data on the prevalence of bio-markers of infection or vaccination, is a potentially powerful tool to understand the epidemiology of infection before vaccination and to monitor the effectiveness of vaccination programmes. Global and national burden of disease estimates for hepatitis B and rubella are based almost exclusively on serological data. Seroepidemiology has helped in the design of measles, poliomyelitis and rubella elimination programmes, by informing estimates of the required population immunity thresholds for elimination. It contributes to monitoring of these programmes by identifying population immunity gaps and evaluating the effectiveness of vaccination campaigns. Seroepidemiological data have also helped to identify contributing factors to resurgences of diphtheria, Haemophilus Influenzae type B and pertussis. When there is no confounding by antibodies induced by natural infection (as is the case for tetanus and hepatitis B vaccines), seroprevalence data provide a composite picture of vaccination coverage and effectiveness, although they cannot reliably indicate the number of doses of vaccine received. Despite these potential uses, technological, time and cost constraints have limited the widespread application of this tool in low-income countries. The use of venous blood samples makes it difficult to obtain high participation rates in surveys, but the performance of assays based on less invasive samples such as dried blood spots or oral fluid has varied greatly. Waning antibody levels after vaccination may mean that seroprevalence underestimates immunity. This, together with variation in assay sensitivity and specificity and the common need to take account of antibody induced by natural infection, means that relatively sophisticated statistical analysis of data is required. Nonetheless, advances in assays on minimally invasive samples may enhance the feasibility of including serology in large survey programmes in low-income countries. In this paper, we review the potential uses of seroepidemiology to improve vaccination policymaking and programme monitoring and discuss what is needed to broaden the use of this tool in low- and middle-income countries.

Corynebacterium ulcerans cutaneous diphtheria

We describe the case of a patient with cutaneous diphtheria caused by toxigenic Corynebacterium ulcerans who developed a right hand flexor sheath infection and symptoms of sepsis such as fever, tachycardia, and elevated C-reactive protein, after contact with domestic cats and dogs, and a fox. We summarise the epidemiology, clinical presentation, microbiology, diagnosis, therapy, and public health aspects of this disease, with emphasis on improving recognition. In many European countries, C ulcerans has become the organism commonly associated with cutaneous diphtheria, usually seen as an imported tropical disease or resulting from contact with domestic and agricultural animals. Diagnosis relies on bacterial culture and confirmation of toxin production, with management requiring appropriate antimicrobial therapy and prompt administration of antitoxin, if necessary. Early diagnosis is essential for implementation of control measures and clear guidelines are needed to assist clinicians in managing clinical diphtheria. This case was a catalyst to the redrafting of the 2014 national UK interim guidelines for the public health management of diphtheria, released as final guidelines in March, 2015.

The financial crisis and the expected effects on vaccinations in Europe: a literature review

Starting in 2008 several European countries experienced a financial crisis. Historically, diseases whose prevention and treatment depend highly on the continuity of healthcare re-emerge during political and financial crises. Evidence suggests that the current financial crisis has had an impact on the health and welfare of Europeans and that population health status and morbidity as well as mortality patterns may change in the coming years. At the same time decisions about expenditure for health services may impact the ability of public health providers to respond. It is expected that the current crisis will further exacerbate socioeconomic and health inequalities and novel vulnerable groups will emerge in addition to existing ones. We review the available evidence and discuss how the current crisis may have an impact on vaccine-preventable diseases and influence vaccination coverage rates in Europe.

Seroepidemiology of diphtheria and tetanus among children and young adults in Tajikistan: nationwide population-based survey, 2010

BACKGROUND

Tajikistan had a major diphtheria outbreak (≈ 10,000 cases) in the 1990 s, which was controlled after nationwide immunization campaigns with diphtheria-tetanus toxoid in 1995 and 1996. Since 2000, only 52 diphtheria cases have been reported. However, in coverage surveys conducted in 2000 and 2005, diphtheria-tetanus-pertussis vaccine coverage was lower than administratively reported estimates raising concerns about potential immunity gaps. To further assess population immunity to diphtheria in Tajikistan, diphtheria antibody testing was included in a large-scale nationwide serosurvey for vaccine-preventable diseases conducted in connection with a poliomyelitis outbreak in 2010. In addition, the serosurvey provided an opportunity to assess population immunity to tetanus.

METHODS

Residents of all regions of Tajikistan aged 1-24 years were included in the serosurvey implemented during September-October 2010. Participants were selected through stratified cluster sampling. Specimens were tested for diphtheria antibodies using a Vero cell neutralization assay and for tetanus antibodies using an anti-tetanus IgG ELISA. Antibody concentrations ≥ 0.1 IU/mL were considered seropositive.

RESULTS

Overall, 51.4% (95% CI, 47.1%-55.6%) of participants were seropositive for diphtheria and 78.9% (95% CI, 74.7%-82.5%) were seropositive for tetanus. The lowest percentages of seropositivity for both diseases were observed among persons aged 10-19 years: diphtheria seropositivity was 37.1% (95% CI, 31.0%-43.7%) among 10-14 year-olds, and 35.3% (95% CI, 29.9%-41.1%) among 15-19 year-olds; tetanus seropositivity in respective age groups was 65.3% (95% CI, 58.4%-71.6%) and 70.1% (95% CI, 64.5%-75.2%).

CONCLUSIONS

Population immunity for diphtheria in Tajikistan is low, particularly among 10-19 year-olds. Population immunity to tetanus is generally higher than for diphtheria, but is suboptimal among 10-19 year-olds. These findings highlight the need to improve routine immunization service delivery, and support a one-time supplementary immunization campaign with diphtheria-tetanus toxoid among birth cohorts aged 1-19 years in 2010 (3-21 years in 2012) to close immunity gaps and prevent diphtheria outbreaks.

Diphtheria in Europe: current problems and new challenges

Diphtheria, caused by toxigenic strains of Corynebacterium diphtheriae, is an ancient disease with high incidence and mortality that has always been characterized by epidemic waves of occurrence. Whilst towards the beginning of the 1980s, many European countries were progressing towards the elimination of diphtheria, an epidemic re-emergence of diphtheria in the Russian Federation and the Newly Independent States of the former Soviet Union demonstrated a continuous threat of the disease into the 1990s. At present, the epidemic is under control and only sporadic cases are observed in Europe. However, the circulation of toxigenic strains is still observed in all parts of the world, posing a constant threat to the population with low levels of seroprotection. More recently, Corynebacterium ulcerans has been increasingly isolated as emerging zoonotic agent of diphtheria from companion animals such as cats or dogs, indicating the enduring threat of this thought-to-be controlled disease.

Comparative seroepidemiology of diphtheria in six European countries and Israel

Serological surveys for diphtheria were conducted in six European countries including Czech Republic, Hungary, Ireland, Latvia, Luxembourg, Slovakia and one country outside Europe, Israel. For each country, a nationally representative population sample was collected across the entire age range and was tested for antibodies to diphtheria toxin. Although each national laboratory used its preferred assay, the results were all standardized to those of the in vitro neutralization test and expressed in international units (IU) which allowed comparative analyses to be performed. The results showed that increasing age is related to a gradual increase in seronegative subjects (<0·01 IU/ml of diphtheria antitoxin antibodies). This may reflect waning immunity following childhood vaccination without repeated booster vaccinations in adults. Differences in seronegativity were also found according to gender. In subjects aged 1-19 years, geometric mean titres of antitoxin are clearly related to the different vaccination schedules used in the participating countries. Although clinical disease remains rare, the susceptibility to diphtheria observed in these serosurveys highlights the importance of strengthened surveillance.

Vaccination recommendations for Germany

BACKGROUND

Vaccination is an effective means of preventing infectious diseases. In Germany, the Standing Vaccination Committee at the Robert Koch Institute (Ständige Impfkommission, STIKO) issues recommendations on vaccination to prevent the occurrence and spread of infectious diseases in the nation's population.

METHODS

Selective literature review, including consideration of the current STIKO recommendations.

RESULTS

The annually updated vaccination calendar currently includes recommendations for vaccination against diphtheria, tetanus, pertussis, type b Haemophilus influenzae, hepatitis B, poliomyelitis, and pneumococci, beginning at the age of eight weeks. From the age of twelve months onward, children should be vaccinated against measles, mumps, rubella, varicella, and serogroup C meningococci. In later childhood and adolescence, booster vaccinations are recommended, in addition to the provision of any vaccinations that may have been missed. Girls aged 12 to 17 years should be vaccinated against human papilloma virus. Adults should have their tetanus and diphtheria vaccinations refreshed regularly, and their pertussis vaccination refreshed once; from age 60 onward, they should be vaccinated against pneumococci and influenza.

CONCLUSIONS

The vaccinations recommended by the STIKO are available to all German citizens free of charge and provide effective protection against infectious disease.

The impact of economic crises on communicable disease transmission and control: a systematic review of the evidence

There is concern among public health professionals that the current economic downturn, initiated by the financial crisis that started in 2007, could precipitate the transmission of infectious diseases while also limiting capacity for control. Although studies have reviewed the potential effects of economic downturns on overall health, to our knowledge such an analysis has yet to be done focusing on infectious diseases. We performed a systematic literature review of studies examining changes in infectious disease burden subsequent to periods of crisis. The review identified 230 studies of which 37 met our inclusion criteria. Of these, 30 found evidence of worse infectious disease outcomes during recession, often resulting from higher rates of infectious contact under poorer living circumstances, worsened access to therapy, or poorer retention in treatment. The remaining studies found either reductions in infectious disease or no significant effect. Using the paradigm of the "SIR" (susceptible-infected-recovered) model of infectious disease transmission, we examined the implications of these findings for infectious disease transmission and control. Key susceptible groups include infants and the elderly. We identified certain high-risk groups, including migrants, homeless persons, and prison populations, as particularly vulnerable conduits of epidemics during situations of economic duress. We also observed that the long-term impacts of crises on infectious disease are not inevitable: considerable evidence suggests that the magnitude of effect depends critically on budgetary responses by governments. Like other emergencies and natural disasters, preparedness for financial crises should include consideration of consequences for communicable disease control.

Immunization safety in US print media, 1995-2005

OBJECTIVE

To identify and describe vaccine safety in US newspaper articles.

METHODS

Articles (1147) from 44 states and Washington, DC, between January 1, 1995, and July 15, 2005, were identified by using the search terms "immunize or vaccine" and "adverse events or safety or exemption or danger or risk or damage or injury or side effect" and were coded by using a standardized data-collection instrument.

RESULTS

The mean number of vaccine-safety articles per state was 26. Six (not mutually exclusive) topics were identified: vaccine-safety concerns (46%); vaccine policy (44%); vaccines are safe (20%); immunizations are required (10%); immunizations are not required (8%); and state/school exemption (8%). Three spikes in the number of newspaper articles about vaccine-safety issues were observed: in 1999 regarding rotavirus vaccine and in 2002 and 2003 regarding smallpox vaccine. Excluding articles that referred to rotavirus and smallpox vaccines, 37% of the articles had a negative take-home message.

CONCLUSION

Ongoing monitoring of news on vaccine safety may help the content and framing of vaccine-safety messages.

Reforming sanitary-epidemiological service in Central and Eastern Europe and the former Soviet Union: an exploratory study

BACKGROUND

Public health services in the Soviet Union and its satellite states in Central and Eastern Europe were delivered through centrally planned and managed networks of sanitary-epidemiological (san-epid) facilities. Many countries sought to reform this service following the political transition in the 1990s. In this paper we describe the major themes within these reforms.

METHODS

A review of literature was conducted. A conceptual framework was developed to guide the review, which focused on the two traditional core public health functions of the san-epid system: communicable disease surveillance, prevention and control and environmental health. The review included twenty-two former communist countries in the former Soviet Union (fSU) and in Central and Eastern Europe (CEE).

RESULTS

The countries studied fall into two broad groups. Reforms were more extensive in the CEE countries than in the fSU. The CEE countries have moved away from the former centrally managed san-epid system, adopting a variety of models of decentralization. The reformed systems remain mainly funded centrally level, but in some countries there are contributions by local government. In almost all countries, epidemiological surveillance and environmental monitoring remained together under a single organizational umbrella but in a few responsibilities for environmental health have been divided among different ministries.

CONCLUSIONS

Progress in reform of public health services has varied considerably. There is considerable scope to learn from the differing experiences but also a need for rigorous evaluation of how public health functions are provided.

Vaccination in the elderly: an immunological perspective

Successful vaccination of the elderly against important infectious pathogens that cause high morbidity and mortality represents a growing public health priority. Building on the theme of aging and immunosenescence, we review mechanisms of human immunosenescence and the immune response to currently licensed vaccines. We discuss the difficulties in identifying the risk factors that, in addition to aging, cause immunosenescence and address the relative paucity of vaccine studies in the elderly. We conclude that vaccine responses are blunted in the elderly compared with that of healthy young adults. However, it is also clear that our understanding of the mechanisms underlying immunosenescence is limited and much remains to be learned to improve the effectiveness of next generation vaccines.

The seroprevalence of diphtheria among adults in Izmir-Turkey

A serological survey to determine the immunity to diphtheria in the adult population in Izmir-Turkey was conducted according to the recommendations of the World Health Organization. A total of 339 blood samples were collected from subjects aged between 20 and 81, and diphtheria antitoxin levels were measured by the enzyme linked immunosorbent assay method. Titers below 0.1 IU/ml were considered to show insufficient immunity. Of the studied population, 56.3% had showed insufficient immunity against diphtheria. Diphtheria protection rates showed a gradual age-related decrease. The lowest immunity rate was observed in 40-49-year age group (30.6%) (p<0.05). There was no significant difference in the rate of immunity between subjects in terms of sex, levels of education, urban-rural region (p>0.05). These results emphasize the need for booster immunization of adults. The present vaccination policy should include re-vaccinations of the adult population every 10 years in order to provide a complete protection of the population.

Diphtheria

Diphtheria is a contagious upper respiratory illness that was a major cause of childhood mortality in the prevaccine era. In the early twentieth century, an effective toxoid vaccine was developed. Implementation of childhood vaccination virtually eliminated diphtheria from developed countries after the Second World War and implementation of the Expanded Program on Immunization in developing countries led to rapid declines in diphtheria globally in the 1980s. However, in the 1990s, a massive epidemic of diphtheria spread throughout the countries of the former Soviet Union. Unlike the prevaccine era, most cases of severe disease and deaths were reported among adults. Multiple factors contributed to the epidemic, including increased susceptibility among both adults and children; suboptimal socioeconomic conditions; high population movement; and delay in implementing appropriate control measures. Mass immunization was the key element in the epidemic control strategy developed and implemented in a well-coordinated response by an international public health coalition. This strategy focused on rapidly raising population immunity of both adults and children; the immunization of more than 140,000,000 adults and adolescents and millions of children successfully controlled the epidemic. While improved coverage of children in developing countries with diphtheria toxoid has led to progressive decreases in diphtheria; eradication is unlikely in the foreseeable future and gaps in immunity among adult population exist or are developing in many other countries. Routine childhood immunization with diphtheria toxoid is the key to controlling diphtheria while the role of routine adult reimmunization is less established; mass immunization will remain an important control measure for widespread diphtheria outbreaks.

Antidiphtheria antibody responses in patients and carriers of Corynebacterium diphtheriae in the Arkhangelsk region of Russia

Diphtheria is under control in industrialized countries. However, single cases and outbreaks still occur and the disease is not completely understood. Forty-three individuals suspected of having diphtheria who were referred to the Infectious Disease Hospital of Arkhangelsk from December 1994 to March 1995 were included in this study. Fifteen patients were diagnosed as having diphtheria and received equine hyperimmune antidiphtheria toxin antiserum, and 28 were diagnosed as carriers, 12 with nondiphtherial tonsillitis or pharyngitis and 16 without symptoms. Serum samples were obtained on admission and during the course of the disease or during follow-up of carrier status. Samples were analyzed for antibodies against diphtheria toxin with both an in vitro neutralization test (NT) and a human-specific enzyme immunoassay. All of the cases but one were confirmed by a positive culture. Twelve patients had pharyngeal diphtheria, and three had combined laryngeal and pharyngeal disease. Half of the patients had life-threatening disease, and one died. On admission, the median antibody titers measured with the NT were 0.085 IU/ml for the patients, 5.12 IU/ml for the symptomatic carriers, and 10.24 IU/ml for the healthy carriers. All of the diphtheria patients but one and nine of the carriers (six symptomatic and three healthy) had increased antibody levels during the first 7 to 10 days after admission. No obvious correlation was revealed between the antibody level or its kinetics and the course of the disease. Antibody levels on admission of >1 IU/ml were associated with a low risk of diphtheria.

Seroprotection against diphtheria and tetanus among Russian and Norwegian teenagers

Russian children between 7 and 10 years of age have been shown to have significantly higher seroprotection against diphtheria compared to Norwegian children. That was due to a reinforcing dose given on entering school to Russian but not to Norwegian children. The next booster was given at the age of 11-12 years in both countries. We have compared diphtheria and tetanus antitoxin levels among 13- to 14- and 15- to 16-year-old teenagers to see if the difference was maintained among the older age group. Serum samples obtained from 106 Russian and 117 Norwegian teenagers were tested by enzyme immunoassay. The Russian and Norwegian adolescents exhibited adequate rates of protection against diphtheria with similar geometric mean antitoxin concentrations of 1.26 and 1.15 IU/ml, respectively, at 13-14 years, and 0.33 and 0.29 IU/ml at 15-16 years. Differences within the age groups were not significant. However, at 13-14 years the Norwegians were much better protected 2 years after a reinforcing dose of tetanus toxoid than the Russians who had not been boosted for 7 years. At the age of 15-16 the difference diminished and became statistically not significant.

Expression of diphtheria toxin inStreptococcus mutansand induction of toxin-neutralizing antisera

The nontoxic full-length diphtheria toxin (DTX), fragment A (DTA), and fragment B (DTB) were each genetically fused to the major surface protein antigen P1 (SpaP) of Streptococcus mutans. Repeated attempts to express the recombinant DTX and DTB in the live oral vaccine candidate Streptococcus gordonii were unsuccessful, whereas DTA could be readily expressed in this bacterium. However, the recombinant DTX, DTB, and DTA could be expressed in the related oral bacterium S. mutans. Western blotting and enzyme-linked immunosorbant assay (ELISA) using anti-DTX and anti-P1 antibodies demonstrated the expression of the three fusion proteins in S. mutans. Mouse antisera raised against the recombinant S. mutans recognized the native DTX in Western immunoblotting. The antibodies raised against S. mutans expressing the recombinant DTX and DTA neutralized the cytotoxicity of the native toxin in a Vero cell assay, but the neutralization titers were relatively low. The potential of using S. gordonii as a live vaccine against diphtheria faces major challenges in the expression of DTX in this organism and in the induction of high-titer toxin-neutralizing antibodies.Key words: diphtheria toxin, Streptococcus mutans, Streptococcus gordonii.

From Pasteur to genomics: progress and challenges in infectious diseases

Over the past decade, microbiology and infectious disease research have undergone the most profound revolution since the times of Pasteur. Genomic sequencing has revealed the much-awaited blueprint of most pathogens. Screening blood for the nucleic acids of infectious agents has blunted the spread of pathogens by transfusion, the field of antiviral therapeutics has exploded and technologies for the development of novel and safer vaccines have become available. The quantum jump in our ability to detect, prevent and treat infectious diseases resulting from improved technologies and genomics was moderated during this period by the greatest emergence of new infectious agents ever recorded and a worrisome increase in resistance to existing therapies. Dozens of new infectious diseases are expected to emerge in the coming decades. Controlling these diseases will require a better understanding of the worldwide threat and economic burden of infectious diseases and a global agenda.

Short-term booster effect of diphtheria toxoid in initially long-term protected individuals

The main objective of this study was to investigate the booster antibody response in individuals with initially high levels of diphtheria antitoxin. Sixty individuals eligible for the routine booster by the age of 18 years each received a single dose of 5 Lf of diphtheria toxoid in diphtheria-tetanus vaccine. A double antigen ELISA was used for the assessment of the antibody levels. Chaotropic disruption in paired ELISA was used to test antibody avidity. The ratio between initial and maximum antibody concentrations after 1 month was >10 times higher and after 6 months still four times higher in those with initial antibody levels <1 IU/ml. In individuals with initial antibody levels >/=1 IU/ml a two-fold decrease was observed after 6 months compared to the initial levels. Thus, vaccination of individuals with initial long-term protection against diphtheria (antibody levels >/=1 IU/ml) is unnecessary and should be avoided.

Diphtheria remains a threat to health in the developing world: an overview

Changes in the epidemiology of diphtheria are occurring worldwide. A large proportion of adults in many industrialized and developing countries are now susceptible to diphtheria. Vaccine-induced immunity wanes over time unless periodic booster is given or exposure to toxigenic Corynebacterium diphtheriae occurs. Immunity gap in adults coupled with large numbers of susceptible children creates the potential for new extensive epidemics. Epidemic emergencies may not be long in coming in countries experiencing rapid industrialization or undergoing sociopolitical instability where many of the factors thought to be important in producing epidemic such as mass population movements and difficult hygienic and economic conditions are present. The continuous circulation of toxigenic C. diphtheriae emphasizes the need to be aware of epidemiological features, clinical signs, and symptoms of diphtheria in vaccine era so that cases can be promptly diagnosed and treated, and further public health measures can be taken to contain this serious disease. This overview focused on worldwide data obtained from diphtheria with particular emphasis to main factors leading to recent epidemics, new clinical forms of C. diphtheriae infections, expression of virulence factors, other than toxin production, control strategies, and laboratory diagnosis procedures.

The meaning of microbial exposure, infection, colonisation, and disease in clinical practice

The basic lexicon of infectious diseases includes the terms exposure, infection, colonisation, and disease, which are used to describe the clinical states in which the presence of a microbe in a host is suspected or discovered. Therefore, the lexicon is used to articulate an implied association between a host and a microbe. However, since it is often difficult to use the available clinical and diagnostic tools to discriminate the different ways in which microbes can exist in a host, the lexicon is often used in an ambiguous and imprecise manner. Another factor contributing to imprecise use of the lexicon is that microbial factors are often held responsible for disease pathogenesis. This relegates the part that the host plays in microbial pathogenesis to an exception, which leads to the need for qualification and modification of the terminology of infectious diseases. Recently, we proposed the "damage-response framework" to incorporate the contributions of both the host and the microbe in microbial pathogenesis in a synthesis whereby host damage was used as the common denominator to describe the outcome of the host-microbe relation. In this article, we illustrate how the application of the damage-response framework to clinical infectious diseases can clarify and make more precise the terminology used to convey the outcome of microbial infection in clinical practice.

Molecular characterization of Corynebacterium diphtheriae isolates, Russia, 1957-1987

In the 1990s, the Newly Independent and Baltic States of the former Soviet Union experienced the largest diphtheria outbreak since the 1960s; it was caused by Corynebacterium diphtheriae strains of a unique clonal group. To address its origin, we studied 47 clinical isolates from Russia and demonstrated that this clonal group was an integral part of the endemic reservoir that existed in Russia at least 5 years before the epidemic began.

The dangerous needles in the haystack of sore throats

The two reports of patients with sore throat published this month (p. 435, 436) highlight life-threatening aspects of that condition. Such rare but clinically highly significant entities remain buried among the far more common sore throats usually associated with the cold and wet British winter; but just because they are rare manifestations of a common disease leaves no room for complacency when assessing the patient with pharyngitis.

Successful control of epidemic diphtheria in the states of the Former Union of Soviet Socialist Republics: lessons learned

Epidemic diphtheria reemerged in the Russian Federation in 1990 and spread to all Newly Independent States (NIS) and Baltic States by the end of 1994. Factors contributing to the epidemic included increased susceptibility of both children and adults, socioeconomic instability, population movement, deteriorating health infrastructure, initial shortages of vaccine, and delays in implementing control measures. In 1995, aggressive control strategies were implemented, and since then, all affected countries have reported decreases of diphtheria; however, continued efforts by national health authorities and international assistance are still needed. The legacy of this epidemic includes a reexamination of the global diphtheria control strategy, new laboratory techniques for diphtheria diagnosis and analysis, and a model for future public health emergencies in the successful collaboration of multiple international partners. The reemergence of diphtheria warns of an immediate threat of other epidemics in the NIS and Baltic States and a longer-term potential for the reemergence of vaccine-preventable diseases elsewhere. Continued investment in improved vaccines, control strategies, training, and laboratory techniques is needed.

Epidemic diphtheria in the 1990s: Azerbaijan

The diphtheria epidemic in the former Soviet Union reached Azerbaijan in 1991, when 66 cases of diphtheria were reported, a number that compared with 4 cases in 1990. From 1990-1996, 2182 cases of diphtheria and 286 diphtheria fatalities (case fatality rate: 13.1%) were reported in Azerbaijan, primarily among persons 5-39 years of age. Almost 45% of cases and 61% of deaths occurred among children 5-14 years of age. The high burden of severe disease among children and young adults suggested a different pattern of preexisting immunity against diphtheria in the Azerbaijani population than was observed in the concurrent diphtheria epidemic in Russia. Because resources were limited in Azerbaijan, mass immunization of the population was carried out in stages, focusing initially on school-aged children. Mass immunization campaigns targeting children were moderately successful in stabilizing the epidemic; mass immunization campaigns targeting both adults and children were eventually needed to fully stop the epidemic.