Implementation of a mass measles campaign in central Afghanistan, December 2001 to May 2002.

In Afghanistan health services have been disrupted by 23 years of conflict and 1 of 4 children die before age 5 years. Measles accounts for an estimated 35,000 deaths annually. Surveillance data show a high proportion of measles cases (38%) among those >/=5 years old. In areas with complex emergencies, measles vaccination is recommended for those aged 6 months to 12-15 years. From December 2001 to May 2002, Afghan authorities and national and international organizations targeted 1,748,829 children aged 6 months to 12 years in five provinces in central Afghanistan for measles vaccinations. Two provinces reported coverage of >90% and two >80%. Coverage in Kabul city was 62%. A subsequent cluster survey in the city found 91% coverage (95% confidence interval [CI], 0.85-0.91) among children 6-59 months and 88% (95% CI, 0.87-0.95) among those 5-12 years old. Thus, this campaign achieved acceptable coverage despite considerable obstacles.

Persistence of a distinct Corynebacterium diphtheriae clonal group within two communities in the United States and Canada where diphtheria is endemic.

Molecular characterization of 53 U.S. and Canadian Corynebacterium diphtheriae isolates by multilocus enzyme electrophoresis, ribotyping, and random amplified polymorphic DNA showed that strains with distinct molecular subtypes have persisted in the United States and Canada for at least 25 years. These strains are endemic rather than imported from countries with current endemic or epidemic diphtheria.

Epidemiology of diphtheria in South Dakota.

Respiratory diphtheria was one of the most common causes of death among children in the pre-vaccine era. Since the introduction of diphtheria toxoid vaccine in 1920s, and its widespread use by the late 1940s, diphtheria became increasingly rare in the United States. However, through the 1970s diphtheria remained endemic in some states, with reported incidence rates > 1.0 per million population in six states (Alaska, Arizona, Montana, New Mexico, South Dakota, and Washington). Starting in 1980, less than five cases have been reported each year in the United States. The majority of culture-confirmed cases have been associated with importation from other countries. Toxigenic Corynebacterium diphtheriae, the organism causing diphtheria, was thought to have become rare or even have disappeared from previously endemic areas such as South Dakota. However, during four months in 1996, 11 persons (one index case, six patients and four household contacts) in an American Indian community in South Dakota were found to be infected by C. diphtheriae; six of these isolates were toxigenic. The findings in this report indicate that despite 20 years without reported respiratory diphtheria cases, toxigenic C. diphtheriae is still present in South Dakota. The continuous circulation of toxigenic strains of C. diphtheriae emphasizes the need for health care providers throughout South Dakota to promote timely vaccination against diphtheria among persons of all ages and ethnic groups, to be aware of the clinical signs and symptoms of diphtheria so that cases can be promptly diagnosed and treated, and further public health measures can be taken to contain this serious disease.

Epidemic diphtheria in Ukraine, 1991-1997.

In 1991, Ukraine experienced a return of epidemic diphtheria after decades of control that had resulted in <40 sporadic cases reported every year. Increased incidence was first recorded in Kiev, Lviv, and Odessa. By 1993, the epidemic had spread to >50% of the oblasts (provinces) in the country, and by 1995, all regions were affected. In 1995, at the peak of the epidemic, >5,000 cases and >200 deaths were reported. As in Russia, >80% of these cases were diagnosed in persons 16-59 years old. In 1993, the government of Ukraine initiated a program of increased immunization among children and at-risk adults, and by 1995, a mass immunization strategy was adopted in an effort to arrest the epidemic, which was increasing exponentially. In 1996, the number of cases started to decrease, and data from 1998 indicate that the downward trend has continued. It is likely that the diphtheria epidemic in Ukraine started among children, who had been left vulnerable due to inadequate childhood immunizations, and then quickly spread to inadequately protected adults.

Evaluation of a single dose of diphtheria-tetanus toxoids among adults in Odessa, Ukraine, 1995: immunogenicity and adverse reactions.

Epidemic diphtheria spread to Ukraine in 1991, where it peaked in 1995 with >5,000 reported cases. To refine epidemic control strategies, immunogenicity of a tetanus-diphtheria toxoids vaccine (Td) containing 2 limits of flocculation (Lf) diphtheria toxoid was evaluated. During a mass vaccination campaign, adults at a clinic in Odessa received one dose of Td. At enrollment, 57.2% of 341 study participants had levels of diphtheria antitoxin (DAT) >/=0.1 IU/mL. Thirty and 180 days after receiving one dose of Td, 91.5% and 84.5% of the participants, respectively, had DAT levels >/=0.1 IU/mL. However, among 40- to 49-year-old participants, only 78.8% and 73.8% had DAT levels >/=0.1 IU/mL at 30 and 180 days, respectively. This study suggests that one dose of 2 Lf diphtheria toxoid is highly effective in raising DAT to protective levels in most adults; however, the study also shows that certain age groups, particularly persons 40-49 and, to a lesser degree, 30-39 years old may require additional doses or a complete three-dose primary vaccination series for optimal protection against diphtheria.

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

The re-emergence of diphtheria in the Newly Independent States of the former Soviet Union in the 1990s raised global awareness of the potential for resurgent disease in countries with long-standing immunization programs. In the United States, the large population of susceptible adults and the possibility of a reintroduction of toxigenic strains of diphtheria create a setting in which diphtheria could spread. In addition, at least one focus of continued circulation of endemic toxigenic Corynebacterium diphtheriae has been identified. Few physicians now have expertise in the diagnosis and treatment of persons with diphtheria, and laboratory capacity is lacking throughout the country. These concerns highlight the importance of maintaining high levels of age-appropriate diphtheria toxoid vaccination, surveillance, accessible and reliable laboratory testing, and training of health care providers. Although the risk of resurgence of diphtheria in the United States is low, public health authorities must ensure that the capacity to recognize, diagnose, and control diphtheria is maintained.

Use of molecular subtyping to document long-term persistence of Corynebacterium diphtheriae in South Dakota.

Enhanced surveillance of patients with upper respiratory symptoms in a Northern Plains community revealed that approximately 4% of them were infected by toxigenic Corynebacterium diphtheriae of both mitis and gravis biotypes, showing that the organism is still circulating in the United States. Toxigenic C. diphtheriae was isolated from five members of four households. Four molecular subtyping methods-ribotyping, multilocus enzyme electrophoresis (MEE), random amplified polymorphic DNA (RAPD), and single-strand conformation polymorphism-were used to molecularly characterize these strains and compare them to 17 archival South Dakota strains dating back to 1973 through 1983 and to 5 isolates collected from residents of diverse regions of the United States. Ribotyping and RAPD clearly demonstrated the household transmission of isolates and provided precise information on the circulation of several distinct strains within three households. By MEE, most recent and archival South Dakota strains were identified as closely related and clustered within the newly identified ET (electrophoretic type) 215 complex. Furthermore, three recent South Dakota isolates and eight archival South Dakota isolates were indistinguishable by both ribotyping and RAPD. All of these molecular methods showed that recent South Dakota isolates and archival South Dakota isolates were more closely related to each other than to the C. diphtheriae strains isolated in other parts of the United States or worldwide. The data also supported the improbability of importation of C. diphtheriae into this area and rather strongly suggest the long-term persistence of the organism in this region.