Epidemic diphtheria in Belarus, 1992-1997. (41/988)

In 1990, epidemic diphtheria reemerged in Russia and spread to Belarus in 1992, when 66 cases were reported. Diphtheria cases doubled each year in 1993 and 1994 and peaked in 1995, when 322 cases were reported. Intensified routine immunization of young children and mass vaccination of older children and selected groups of adults were conducted in 1995 and were followed by mass vaccination campaigns targeting all adults in 1996. By the end of 1996, full immunization of >95% of children and coverage of>87% of adults with >/=1 dose resulted in a rapid decline in diphtheria cases. In 1998, only 36 cases of diphtheria were reported. More than 70% of the 965 cases and 26 fatalities reported during 1990-1998 occurred among persons >14 years of age. High levels of immunity among the entire population are needed for rapid control of diphtheria epidemics in the vaccine era.  (+info)

Epidemiology and control of diphtheria in the Republic of Moldova, 1946-1996. (42/988)

In 1994-1996, the Republic of Moldova was stricken with an epidemic of diphtheria after >30 years of routine diphtheria immunization and the near absence of the disease for nearly 20 years. The intensity of the epidemic gradually grew, reaching a peak in 1994-1995. The epidemiology of diphtheria in Moldova during this period is described along with laboratory findings and control measures. Pharyngeal diphtheria was the predominant clinical form of the disease (97% of cases), and it most often developed in a localized form (70%), with 20% in the toxic form. The clinical diagnosis of diphtheria was bacteriologically confirmed in 91% of cases: Of the cases tested for biotype, 91.3% were gravis, 8.5% were mitis, and 0. 2% were intermedius. Of 494 toxigenic isolates from cases and carriers at the beginning of the epidemic, 47% were nonphagotypeable strains, and 25.7% were phagotype VI strains. Aggressive population-based diphtheria control measures, a mass immunization campaign, rapid case identification, antibiotic prophylaxis and supplemental immunization of close contacts in clusters of infection, and high coverage with routine immunization rapidly controlled the epidemic within Moldova.  (+info)

Diphtheria in Lithuania, 1986-1996. (43/988)

Diphtheria reappeared in Lithuania in 1986 and rose to epidemic levels by 1992. Between 1991 and 1996, 110 cases of diphtheria were registered, with an incidence of 0.03-1.15/100,000 population. Most cases (84%) and all 17 deaths occurred among persons >/=15 years, most of whom had never been vaccinated. Persons 40-49 years old had the highest average annual age-specific morbidity (1.70/100,000) and mortality (0.53/100,000) rates. Low levels of immunity among individuals 40-49 years old and migration to epidemic areas in Russia and Belarus contributed to the epidemic's occurrence. Between 1991 and 1995, toxigenic Corynebacterium diphtheriae strains were isolated from 84 of all registered patients (76%), and nontoxigenic strains were isolated from 13 (12%). By 1996, two mass vaccination campaigns, which provided one dose of vaccine to individuals 25-30 years old and three doses of vaccine to persons 31-60 years old, helped reduce the number of cases. The first campaign achieved 69% coverage; the second achieved 48% coverage.  (+info)

Epidemic investigation of diphtheria in the Republic of Armenia, 1990-1996. (44/988)

While incidence rates of diphtheria steadily declined in Armenia after World War II, reemergence of the disease in 1990 brought about changes in public health practices and identified resource needs. The Armenian Ministry of Health (MOH) routinely collected diphtheria case reports, as a reportable health outcome. Diphtheria incidence rates increased from 0.02/100,000 in 1993 to 1/100,000 (36 cases) in 1994. The distribution of cases showed that the greatest number of illnesses and deaths occurred among persons 5-14 years old, yet incidence rates among persons 1-4 and 5-14 years old were similar (4. 4 cases/ and 4.3 cases/100,000, respectively). During 1990-1996, 9 (75%) of 12 cases who died and 18 (21%) of 84 cases who survived had not been vaccinated. The diphtheria epidemic in Armenia was an important, serious, and signal public health event. The Armenian MOH responded by revising immunization practices (1994), improving epidemic control measures (1995), and soliciting international resources (1992-1996).  (+info)

Epidemic diphtheria in the Kyrgyz Republic, 1994-1998. (45/988)

The Kyrgyz Republic experienced a widespread diphtheria epidemic during 1994-1998. National diphtheria surveillance and vaccination coverage information were used to describe the course of the epidemic. The epidemic began in August 1994, reached a peak in 1995 with 704 cases (incidence rate: 15.4/100,000 population) and 30 deaths, and declined to an incidence rate of 4.0/100,000 during the first 8 months of 1998. Age-specific incidence was highest in 1995 among persons 15-19 and 20-29 years old. Three rounds of mass vaccination with tetanus and diphtheria toxoids for adult use (Td) were conducted; reported coverage was 69% in 1995 and >95% in 1996 and 1997. Reported routine vaccination coverage with three doses of diphtheria toxoid by age 12 months increased from 62% in 1989 to 98% in 1997. Mass vaccination of the adult population with Td and improvements in childhood vaccination coverage played a major role in controlling the epidemic.  (+info)

Diphtheria epidemic in the Republic of Uzbekistan, 1993-1996. (46/988)

The Republic of Uzbekistan, like the other Newly Independent States in the 1990s, experienced epidemic diphtheria during the 1990s. The outbreak in Uzbekistan began in 1993 in southern regions that bordered areas of Tajikistan that were experiencing a very intense diphtheria epidemic. However, the Uzbek epidemic rapidly spread and threatened to involve the entire country. From 1993-1996, 1169 cases of diphtheria were reported, compared with 58 in 1990-1992. Unvaccinated or only partially vaccinated cases were more likely to have clinically severe forms of diphtheria than those who were fully vaccinated. Strong epidemiologic links with the Tajik diphtheria epidemic and the predominance of mitis biotype strains of Corynebacterium diphtheriae in Uzbekistan make it likely that the Uzbek outbreak arose independently of the predominantly biotype gravis epidemic that began in Russia. The epidemic appeared to be due to low population immunity and the large-scale reintroduction of toxigenic strains of C. diphtheriae. Several mass vaccination campaigns and general enhancement of routine immunization procedures led to control of the epidemic in 1996.  (+info)

Ukraine, 1992: first assessment of diphtheria vaccine effectiveness during the recent resurgence of diphtheria in the Former Soviet Union. (47/988)

A case-control study in Ukraine provided the first data on the field effectiveness of Russian-produced vaccine during the 1990 diphtheria resurgence in the former Soviet Union. For each of 262 diphtheria cases <15 years of age who were reported from January through October 1992, 2 controls, matched by age and clinic, were selected. The effectiveness of three doses of diphtheria vaccine was 98.2% (95% confidence interval: 90.3-99.9). Among controls, 84% had received three or more vaccinations by 2 years of age. These results suggest that the following five hypothesized causes of the outbreak appeared unlikely: appearance of a new "mutant" diphtheria strain, low potency of the Russian-produced diphtheria vaccine, inadequate cold chain, poor host immunogenicity due to radiation exposure from Chernobyl, and low routine childhood vaccination coverage. It is concluded that initial priority for scarce resources for controlling this outbreak should be placed on vaccination of persons susceptible to diphtheria (e.g., adults) rather than revaccination of children.  (+info)

Immunogenicity of tetanus-diphtheria toxoids (Td) among Ukrainian adults: implications for diphtheria control in the Newly Independent States of the Former Soviet Union. (48/988)

After 30 years of control, epidemic diphtheria returned to the Soviet Union in 1990. To develop control strategies, the immunogenicity of the tetanus and diphtheria toxoids (Td) vaccine was assessed. Workers who were 18-67 years old received two Td immunizations separated by 30 days. A neutralization assay determined diphtheria antitoxin (DAT) on enrollment and on days 7, 30, 60, and 425. On enrollment, 43.0% of 488 workers had DAT <0.1 IU/mL. After one dose, 88.5% had DAT >/=0.1 IU/mL, after two doses, 92.2% had >/=0.1 IU/mL and >90% of participants <30 or >/=50 years of age attained >/=1.0 IU/mL; however, only 78.4% of those who were 30-39 years old and 51.8% of those who were 40-49 years old achieved >/=1.0 IU/mL after two doses. To control the epidemic in Ukraine, one Td dose should be administered to virtually the entire population (persons 30-49 years old require three doses of Td for optimal individual protection and to maximize population immunity).  (+info)