Think globally, act locally: the role of local demographics and vaccination coverage in the dynamic response of measles infection to control

The global reduction of the burden of morbidity and mortality owing to measles has been a major triumph of public health. However, the continued persistence of measles infection probably not only reflects local variation in progress towards vaccination target goals, but may also reflect local variation in dynamic processes of transmission, susceptible replenishment through births and stochastic local extinction. Dynamic models predict that vaccination should increase the mean age of infection and increase inter-annual variability in incidence. Through a comparative approach, we assess national-level patterns in the mean age of infection and measles persistence. We find that while the classic predictions do hold in general, the impact of vaccination on the age distribution of cases and stochastic fadeout are mediated by local birth rate. Thus, broad-scale vaccine coverage goals are unlikely to have the same impact on the interruption of measles transmission in all demographic settings. Indeed, these results suggest that the achievement of further measles reduction or elimination goals is likely to require programmatic and vaccine coverage goals that are tailored to local demographic conditions.

Molecular epidemiology of Bordetella pertussis by pulsed-field gel electrophoresis profile: Cincinnati, 1989-1996

Reported cases of pertussis have increased in the United States, with peaks occurring every few years. Bordetella pertussis isolates collected in Cincinnati from 1989 to 1996 were analyzed with pulsed-field gel electrophoresis (PFGE), to evaluate trends. Among 496 isolates, 30 PFGE profiles were identified; 32% were CYXXI-010, the profile that predominated each year. Eighteen profiles (198 strains) were identified in 1989-1992, 20 profiles (197 strains) were identified during the 1993 epidemic, and 11 profiles (101 strains) were identified in 1994-1996. From 1989 to 1996, among 42 patients, isolates from household members in 17 (89%) of 19 households had concordant PFGE profiles. There was no association between PFGE profile and seasonality, age, and hospitalization or pneumonia in infants <1 year old. The 1993 epidemic was associated primarily with an increased prevalence of PFGE profiles that circulated before and after 1993, which suggests that the epidemic was due to factors other than the emergence of a novel B. pertussis strain.

Measles eradication: is it in our future?

Measles eradication would avert the current annual 1 million deaths and save the $1.5 billion in treatment and prevention costs due to measles in perpetuity. The authors evaluate the biological feasibility of eradicating measles according to 4 criteria: (1) the role of humans in maintaining transmission, (2) the availability of accurate diagnostic tests, (3) the existence of effective vaccines, and (4) the need to demonstrate elimination of measles from a large geographic area. Recent successes in interrupting measles transmission in the United States, most other countries in the Western Hemisphere, and selected countries in other regions provide evidence for the feasibility of global eradication. Potential impediments to eradication include (1) lack of political will in some industrialized countries, (2) transmission among adults, (3) increasing urbanization and population density, (4) the HIV epidemic, (5) waning immunity and the possibility of transmission from subclinical cases, and (6) risk of unsafe injections. Despite these challenges, a compelling case can be made in favor of measles eradication, and the authors believe that it is in our future. The question is when.

Economic evaluation of use of diphtheria, tetanus, and acellular pertussis vaccine or diphtheria, tetanus, and whole-cell pertussis vaccine in the United States, 1997

OBJECTIVE

To compare the economic costs and benefits associated with using either diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) or diphtheria and tetanus toxoids and whole-cell pertussis vaccine (DTwP) in the United States in 1997.

DESIGN

Standard cost-benefit analysis, from both the societal and health care system perspectives, was performed for each combination vaccine as well as for the pertussis components singly.

SETTING

A simulated cohort of 4.1 million children from birth to age 15 years.

MAIN OUTCOME MEASURES

Net costs (savings) and benefit-cost ratios (BCRs)

RESULTS

Without a vaccination program, diphtheria, tetanus, and pertussis disease caused more than 3 million cases and more than 28,000 deaths, at a cost of $23.6 billion. From the societal perspective, net savings because of the use of DTaP and DTwP were $22.510 million and $22.623 million, respectively. The net savings from the acellular pertussis component and the whole-cell pertussis component only were $4.362 million and $4.474 million, respectively. Benefit-cost ratios for DTaP from a societal and health care system perspective were 27:1 and 9:1, respectively. Sensitivity analyses of key variables did not result in appreciable changes in results.

CONCLUSIONS

Compared with no program, vaccination with DTaP or DTwP resulted in substantial savings, regardless of the perspective taken and for all sensitivity analyses conducted. Compared with DTwP, use of DTaP generated a small cost increase that might be offset by the value of other factors, such as increased confidence in pertussis vaccination resulting from reduced adverse events. Arch Pediatr Adolesc Med. 2000;154:797-803

Factors determining prevalence of maternal antibody to measles virus throughout infancy: a review

The effectiveness of vaccination against measles, the leading cause of vaccine-preventable deaths in infants globally, is greatly impacted by the level of maternal antibody to measles virus (or "measles maternal antibody"; MMA) during infancy. Variation in the prevalence of maternal antibody to measles virus between infant populations across countries and sociodemographic strata is poorly understood. We reviewed the literature on the prevalence of MMA, focusing on 3 principal determinants: starting level of maternal antibody, placental transfer of maternal antibody, and rate of decay of maternal antibody after birth. Our review identified placental transfer as an important determinant, with greater efficiency found in studies performed in developed countries. Placental transfer was influenced by gestational age, human immunodeficiency virus infection, and malaria. Antibody levels in mothers varied widely between countries, although predictably according to vaccination status within populations. Rates of antibody decay across studies were similar. Future studies should evaluate the utility of the cord blood level of MMA as a predictor of vaccine efficacy in infancy; inclusion of World Health Organization international reference sera will facilitate comparisons. Greater understanding of the determinants of the prevalence of MMA will help national policy makers determine the appropriate age for measles vaccination.

Clinical characteristics and management of 676 hospitalized diphtheria cases, Kyrgyz Republic, 1995

The Kyrgyz Republic experienced a widespread resurgence of diphtheria during 1994-1998. To describe the clinical characteristics and management of diphtheria patients hospitalized in 1995, a retrospective chart review was conducted. Physician-diagnosed cases of diphtheria were classified according to the system recommended by the World Health Organization and UNICEF. Among 676 patients hospitalized with respiratory diphtheria, 163 (24%) were carriers, 186 (28%) had tonsillar forms, 78 (12%) had combined types or delayed diagnosis, and 201 (30%) had severe forms of diphtheria. The highest age-specific incidence rates occurred among persons 15-34 years old, and 70% of cases were among those >/=15 years of age. Myocarditis occurred among 151 patients (22%), and 19 patients died (case fatality ratio: 3%). Diphtheria antitoxin was administered to 507 patients (75%), and all patients received antibiotics (penicillin or erythromycin). Respiratory diphtheria remains a potentially fatal disease, commonly presenting with a typical membranous pharyngitis. Early diagnosis and treatment of cases with diphtheria antitoxin and antibiotics are the cornerstones of effective treatment.

Epidemic diphtheria in the Kyrgyz Republic, 1994-1998

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.

Risk factors for diphtheria: a prospective case-control study in the Republic of Georgia, 1995-1996

The large-scale resurgence of diphtheria in the former Soviet Union offered a unique opportunity to evaluate risk factors for the transmission of respiratory diphtheria; therefore, a prospective case-control study was done in the republic of Georgia. In total, 218 diphtheria cases (hospitalized between October 1995 and March 1996) and 408 matched controls participated. One hundred cases (45%) were </=14 years of age, and 118 (55%) were >/=15 years of age (range: <1 to 75 years). In the multivariate analyses, the following risk factors were found to be significant: lack of vaccination (matched odds ratio [mOR]=19.2), household exposure to diphtheria (mOR=7.4), exposure to skin lesions (mOR=5.8), history of eczema (mOR=3.4), fever with myalgia prior to illness (mOR=2.6), having tonsils (mOR=4.4), sharing a bed (mOR=1.9), sharing cups and glasses (mOR=2.7), and taking a bath less than once a week (mOR=2.6). These findings emphasize primary prevention through immunizations, secondary prevention following exposure to diphtheria (and to suspicious skin lesions), and adherence to strict standards of personal hygiene.

Epidemic diphtheria in the Republic of Georgia, 1993-1996: risk factors for fatal outcome among hospitalized patients

Epidemic diphtheria reemerged in the republic of Georgia in November 1993. To identify risk factors for fatal outcomes, clinical and epidemiologic data on all hospitalized diphtheria patients were examined. Medical charts of patients from 1993-1995 were reviewed. A total of 659 cases and 68 deaths were identified (case fatality rate [CFR] = 10.3%). Fifty-two percent of all cases and 68% of deaths were in children </=14 years old. The highest CFR occurred among adults 40-49 years of age (CFR=19%) and children 5-9 years of age (CFR=16%). Children who did not have the complete primary vaccination series with diphtheria toxoid and adults 40-49 years of age were the 2 groups at highest risk. Being a rural resident and having a long interval (>3 days) between onset of symptoms to antitoxin treatment were significantly associated with fatal outcomes. Immunization of children and 40- to 49-year-old adults was required to rapidly control the epidemic.

Measles epidemic in Romania, 1996-1998: assessment of vaccine effectiveness by case-control and cohort studies

A measles epidemic occurred in Romania with 32,915 cases and 21 deaths reported between November 1996 and June 1998, despite high vaccination coverage since the early 1980s. Most cases were unvaccinated children aged <2 years and vaccinated school-aged children. A case-control study among preschool children and a cohort study among primary-school children were conducted to estimate effectiveness of Romanian-produced measles vaccine, and to evaluate age at vaccination and waning immunity as risk factors for vaccine failure. Both studies indicated that measles vaccine was highly effective. One dose reduced the risk for measles by 89% (95% confidence interval (CI) 85, 91); two doses reduced the risk by 96% (95% CI 92, 98). Children vaccinated at <1 year of age were not at increased risk for measles compared with children vaccinated at > or =1 year. Waning immunity was not identified as a risk factor since vaccine effectiveness was similar for children vaccinated 6-8, 9-11, and 12-14 years in the past. Because specific groups were not at risk for vaccine failure, an immunization campaign that targets all school-aged children who lack two doses may be an effective strategy for preventing outbreaks. A mass campaign followed by increased first-dose coverage should provide the population immunity required to interrupt indigenous measles virus transmission in Romania.

Changing epidemiology of pertussis in the United States: increasing reported incidence among adolescents and adults, 1990-1996

Since 1990, the reported incidence of pertussis has increased in the United States with peaks occurring every 3-4 years. On the basis of analysis of pertussis cases reported to the Centers for Disease Control and Prevention, the incidence remained stable among children aged younger than 5 years, most of whom were protected by vaccination. In contrast to 1990-1993, during 1994-1996, the average incidence among persons aged 5-9 years, 10-19 years, and 20 years or older increased 40%, 106%, and 93%, respectively. Since 1990, 14 states reported pertussis incidences of > or =2 cases per 100,000 population during at least 4 years between 1990 and 1996; seven of these states also reported that a high proportion of cases occurred in persons aged 10 years or older. Analysis of national data on pertussis did not provide sufficient information to fully elucidate the relative importance of multiple possible explanations for the increase in the incidence of pertussis in adolescents and adults. Improvement in diagnosis and reporting of pertussis in this age group, particularly in some states, is an important factor contributing to the overall increase.

Risk of diphtheria among schoolchildren in the Russian Federation in relation to time since last vaccination

BACKGROUND

Between 1990 and 1996, more than 110,000 cases and 2900 deaths from diphtheria were reported in the Russian Federation. In 1994, because disease rates were high among children aged 7-10 years, the age of administration of the second booster dose of diphtheria vaccine was lowered from 9 years to 6 years, the age of school entry. To assess the impact of this policy change, we did a matched case-control study in three Russian cities.

METHODS

Children aged 6-8 years who had diphtheria between September, 1994, and December, 1996, were each matched with five to seven children acting as controls who were within 3 months of age of the case and were from the same class at school. We did a matched analysis using conditional logistic regression.

FINDINGS

We analysed the immunisation records of 58 cases and 306 controls. All but one case and all controls had received at least three doses of diphtheria-toxoid vaccine. 19 (33%) cases and 144 (47%) controls had received a booster dose of diphtheria toxoid within the previous 2 years. Cases were more likely than were controls to have received only four doses rather than five (odds ratio 2.8 [95% CI 1.2-6.5]) and to have a time since the last dose of diphtheria toxoid of 3-4 years (3.1 [1.1-9.1]) or 5-7 years (15.0 [2.5-89.0]), compared with children for whom it was 2 years or less. On multivariate analysis only a time since the last dose of 5-7 years remained significantly associated with disease (matched odds ratio adjusted for total number of doses 10.9 [1.6-75.1]).

CONCLUSION

A booster dose of diphtheria-toxoid vaccine given to children in the Russian Federation at 6-8 years of age reduced the interval since the last dose of diphtheria toxoid and improved protection against diphtheria.

Epidemiology of epidemic diphtheria in three regions, Russia, 1994-1996

BACKGROUND

A massive diphtheria epidemic which began in the former Soviet Union in 1990 is the first large-scale diphtheria epidemic in developed countries in more than 30 years and has primarily affected adults. In response, health authorities attempted to maximize vaccination for children and conducted an unprecedented campaign to vaccinate adults.

METHODS

We analyzed diphtheria surveillance data (case report forms and diphtheria vaccine coverage data) from three Russian regions from January 1994 to December 1996 and estimated vaccine effectiveness by the screening method.

RESULTS

We reviewed records from 2243 (97.2%) of 2307 reported cases. The highest cumulative incidence in the period was among children aged 5 to 9 years (106 cases per 100,000 population); adults aged 40-49 years had the highest adult incidence for disease (88 cases per 100,000) and the highest incidence of any age group of clinically severe disease (29 cases per 100,000) and death (5.1 deaths per 100,000). The incidence among women aged 2049 years (82 per 100,000 women) was higher than among men (47 per 100,000, p<0.01). The annual incidence decreased from 25.2 cases per 100,000 population in 1994 to 9.4 cases per 100,000 in 1996. The decrease occurred as adult coverage increased from an estimated 25-30% in December 1992 to 88% in December 1995. Vaccine effectiveness was high among both children and adults.

CONCLUSIONS

The Russian diphtheria epidemic primarily affected adults, especially women; this pattern is likely representative of diphtheria epidemics in immunized populations. Raising childhood immunization coverage and mass adult vaccination was effective in controlling the Russian epidemic. An improved understanding of the current epidemiology of diphtheria will be useful to design public health responses to prevent or control modern epidemics.

Respiratory diphtheria in the United States, 1980 through 1995

OBJECTIVES

The purpose of this study was to describe the epidemiologic, laboratory, and clinical features of respiratory diphtheria cases reported in the United States during 1980 through 1995.

METHODS

Respiratory diphtheria cases reported to the Centers for Disease Control and Prevention were reviewed. Cases were defined as physician-diagnosed cases with signs and symptoms compatible with respiratory diphtheria, including the presence of a pseudomembrane without other apparent cause.

RESULTS

From 1980 through 1994, 41 respiratory diphtheria cases were reported; none were reported in 1995, and no secondary cases were identified. Nine (22%) case patients were 4 years of age or younger, and 28 (68%) were 15 years of age or older. None of the case patients were up to date with diphtheria vaccination; 4 unvaccinated children died. Seventeen (43%) of 40 case patients had positive culture results.

CONCLUSIONS

Available surveillance data suggest that respiratory diphtheria has become a rare disease in the United States. However, importation and circulation of toxigenic strains continue to present a threat and require achieving and maintaining high coverage with diphtheria toxoid-containing vaccines in both children and adults.

Haemophilus influenzae invasive disease in the United States, 1994-1995: near disappearance of a vaccine-preventable childhood disease

We analyzed national Haemophilus influenzae (Hi) surveillance data from 1994 and 1995 to describe the epidemiology of Hi invasive disease among persons of all ages. Serotype data were available for 376 (56%) of 669 reported Hi cases among children aged 4 years or younger; 184 (49%) were H. influenzae type b (Hib). Among children aged 4 or younger, incidence (per 100,000) of all Hi invasive disease was 1.8 in 1994 and 1.6 (p < 0.05) in 1995. Children aged 5 months or younger had the highest average annual incidence rate of Hib invasive disease (2.2 per 100,000); children aged 6 to 11 months had the next highest rate (1.2 per 100,000)(p < 0.05). Of 181 children with Hib invasive disease whose age in months was known, 85 (47%) were too young (aged 5 months or younger) to have completed a primary series with an Hib-containing vaccine. Of the 83 children with known vaccination status who were eligible to receive a primary series (aged 6 months or older), 52 (63%) were undervaccinated, and the remaining 31 (37%) had completed a primary series in which vaccine failed. Among persons aged 5 years or older with Hi invasive disease, the lowest average annual incidence was among those 20 to 39 years of age (0.15 per 100,000), and the highest was among those aged 80 years or older (2.26 per 100,000). Among persons aged 5 years or older, serotype data were available for 1,372 (71%) of the 1,940 Hi invasive disease cases; 159 (28%) of the 568 Hi cases with known serotype were due to Hib.

Postlicensure effectiveness of varicella vaccine during an outbreak in a child care center

CONTEXT

Because lyophilized varicella vaccine must be stored frozen at -15 degrees C or less (> or = 5 degrees F) and administered within 30 minutes after reconstitution, the potential exists for decreased vaccine effectiveness when the vaccine is used under field conditions.

OBJECTIVES

To describe an outbreak of varicella in a child care center and to determine postlicensure effectiveness of varicella vaccine.

DESIGN

Retrospective cohort study.

SETTING

A child care center in DeKalb County, Georgia, in 1996.

PARTICIPANTS

Of the 184 children registered in the child care center, 148 were eligible for the study based on absence of history of varicella before January 1, 1996.

MAIN OUTCOME MEASURES

Data on disease status, severity and impact of disease, and risk factors for varicella and for vaccine failure were obtained from parents and their children's pediatricians. Varicella vaccine effectiveness was calculated among children aged 12 months or older (eligible for vaccination) using the cohort method.

RESULTS

The outbreak started on January 17, 1996, and lasted 15 weeks. Of the 148 eligible children, 81 (55%) developed varicella. Cases among children younger than 12 months (n =7) were more severe than cases among older children. Varicella occurred in 9 (14%) of 66 vaccinated children and 72 (88%) of 82 unvaccinated children. Varicella was less severe and resulted in fewer days of absence from the child care center among vaccinated compared with unvaccinated cases. Varicella vaccine effectiveness against all forms of disease was 86% (95% confidence interval [CI], 73%-92%), and against moderate-to-severe varicella disease it was 100% (95% CI, 96%-100%). Vaccinated children with asthma or other reactive airway diseases were 7.1 times more likely to have varicella than were vaccinated children without reactive airway diseases (95% CI, 2.4-21.3).

CONCLUSIONS

Varicella vaccine administered under routine conditions in physicians' offices was highly effective in preventing varicella in an outbreak characterized by intense exposure. The role of asthma and other reactive airway diseases as risk factors for varicella disease and vaccine failure deserves to be investigated further.

Effectiveness of the pertussis vaccination program as determined by use of the screening method: United States, 1992-1994

The screening method was used to evaluate the effectiveness of the pertussis vaccination program in the United States during 1992-1994. The formula VE = 1 - [PCV/(1 - PCV)][(1 - PPV)/PPV] was used (VE = vaccine effectiveness; PCV = proportion of cases vaccinated; PPV = proportion of population vaccinated). Data from the national Supplementary Pertussis Surveillance System and the National Health Interview Survey were used to determine PCV and PPV, respectively. Among children aged 7-18 months, VE for 3 doses of pertussis vaccine was 79% (95% confidence interval, 74%-83%) for preventing culture-confirmed pertussis. Between the ages of 19 and 47 months, VE for > or = 4 doses was 90% (95% confidence interval, 88%-92%). VE estimates appeared lower in epidemic (1993) than non-epidemic years (1992, 1994). VE estimates determined using the screening method were consistent with the previous estimates from the United States. This method will continue to be useful for assessing the effectiveness of the pertussis vaccination program in the United States, where acellular pertussis vaccines are recommended for infants.

Poliomyelitis prevention in the United States: new recommendations for routine childhood vaccination place greater reliance on inactivated poliovirus vaccine

Until worldwide eradication of poliomyelitis is achieved, vaccination with poliovirus vaccines is the only means for providing population and individual immunity to polioviruses. The ACIP, AAP, and AAFP support the global poliomyelitis eradication initiative, and have recommended a transition policy that will increase use of IPV and decrease use of OPV during the next 3 to 5 years.

Tetanus surveillance--United States, 1991-1994

PROBLEM/CONDITION

Despite the widespread availability of a safe and effective vaccine against tetanus, 201 cases of the disease were reported during 1991-1994. Of patients with known illness outcome, the case-fatality rate was 25%.

REPORTING PERIOD COVERED

1991-1994.

DESCRIPTION OF SYSTEM

Physician-diagnosed cases of tetanus are reported to local and state health departments, the latter of which reports these cases on a weekly basis to CDC's National Notifiable Disease Surveillance System. Since 1965, state health departments also have submitted supplemental clinical and epidemiologic information to CDC's National Immunization Program.

RESULTS

During 1991-1994, 201 cases of tetanus were reported from 40 states, for an average annual incidence of 0.02 cases per 100,000 population. Of the 188 patients for whom age was known, 101 (54%) were aged > or = 60 years and 10 (5%) were aged < 20 years. No cases of neonatal tetanus were reported. Among adults, the risk for tetanus increased with age; the risk for persons aged > or = 80 years was more than 10 times greater than the risk for persons aged 20-29 years. All deaths occurred among persons aged > or = 30 years. The case-fatality rate (overall: 25%) increased with age, from 11% in persons aged 30-49 years to 54% in persons aged > or = 80 years. Only 12% of all patients were reported to have received a primary series of tetanus toxoid before onset of illness. For 77% of patients, tetanus occurred after an acute injury was sustained. Of patients who obtained medical care for their injury, only 43% received tetanus toxoid as part of wound prophylaxis.

INTERPRETATION

The epidemiology of reported tetanus in the United States during 1991-1994 was similar to that during the 1980s. Tetanus continued to be a severe disease primarily of older adults who were unvaccinated or inadequately vaccinated. Most tetanus cases occurred after an acute injury was sustained, emphasizing the need for appropriate wound management.

ACTIONS TAKEN

In addition to decennial booster doses of tetanus-diphtheria toxoid during adult life, the Advisory Committee on Immunization Practices (ACIP) recommends vaccination visits for adolescents at age 11-12 years and for adults at age 50 years to enable health-care providers to review vaccination histories and administer any needed vaccine. Full implementation of the ACIP recommendations should virtually eliminate the remaining tetanus burden in the United States.

Sequential and combined use of inactivated and oral poliovirus vaccines: Dolj District, Romania, 1992-1994

To determine the feasibility of a vaccination strategy that would reduce the risk of vaccine-associated paralysis while retaining a barrier against the spread of wild poliovirus, a 2-year project was undertaken using enhanced-potency inactivated poliovirus vaccine (IPV) administered at 2 and 3 months of age followed by doses of both IPV and oral poliovirus vaccine (OPV) administered at 4 and 9 months of age. Vaccination coverage by 12 months of age with three or more doses of IPV and two doses of OPV among 16,566 infants eligible for vaccination was > 95% and > 80%, respectively. Among 51 children from whom blood samples were obtained 45 days after their third dose of IPV and first dose of OPV, 100% had serum neutralizing antibodies (reciprocal titer > or = 10) to all three poliovirus types. No cases of paralytic poliomyelitis due to either wild or vaccine-related strains were reported. The project demonstrated the feasibility, safety, and high immunogenicity of sequential use of IPV followed by OPV in Romania.

Exudative pharyngitis possibly due to Corynebacterium pseudodiphtheriticum, a new challenge in the differential diagnosis of diphtheria

Corynebacterium pseudodiphtheriticum has rarely been reported to cause disease in humans, despite its common presence in the flora of the upper respiratory tract. We report here a case of exudative pharyngitis with pseudomembrane possibly caused by C. pseudodiphtheriticum in a 4-year-old girl. The case initially triggered clinical and laboratory suspicion of diphtheria. Because C. pseudodiphtheriticum can be easily confused with Corynebacterium diphtheriae in Gram stain, clarification of its role in the pathogenesis of exudative pharyngitis in otherwise healthy persons is of public health importance. Simple and rapid screening tests to differentiate C. pseudodiphtheriticum from C. diphtheriae should be performed to prevent unnecessary concern in the community and unnecessary outbreak control measures.

Large outbreak of pertussis among young children in Chicago, 1993: investigation of potential contributing factors and estimation of vaccine effectiveness

BACKGROUND

An outbreak of pertussis from July, 1993, to April, 1994, in Chicago was investigated to identify potential contributing factors.

METHODS

Surveillance was enhanced to identify cases. Information from a vaccination coverage survey was used to define a retrospective cohort to estimate vaccine effectiveness of three or more doses of pertussis vaccine.

RESULTS

The median age of 218 reported cases was 8 months, 46% had Hispanic surnames and cases were clustered geographically. Vaccination status was known for 173 of 191 (91%) children younger than 6 years of age. Of these 173, 90 (52%) were younger than 7 months, and 35 (20%) children at least 7 months of age had received fewer than 3 doses of pertussis vaccine. Pertussis vaccine effectiveness was 76% (95% confidence interval, 29 to 92).

CONCLUSIONS

The limited ability of the current pertussis vaccination schedule to protect young infants accounted for 52% of cases, primary vaccine failure accounted for 28% of cases and failure to vaccinate children on time accounted for 20% of cases in young children. Low vaccine effectiveness did not appear to be a contributing factor.

The effect of Edmonston-Zagreb and Schwarz measles vaccines on immune response in infants

The effects of measles immunization on immune responses in infants and the roles of vaccine strain and age of immunization are not known. Eighty-eight children were immunized at 6 or 9 months of age with the Edmonston-Zagreb (EZ) or Schwarz (SW6, SW9) strain of measles vaccine. Children were studied before and 2 weeks and 3 months after immunization. Seroconversion was similar, but geometric mean neutralizing titers at 3 months differed by vaccine group: SW9, 1367 mIU/mL; SW6, 982; and EZ, 303 (P = .003). Mitogen-induced lymphoproliferation was decreased at 2 weeks in the SW9 group and at 3 months in all groups and was negatively correlated with measles antibody level at 3 months (r = -.387, P = .003). CD8 T cells, soluble CD8, neopterin, and beta2-microglobulin were increased at 2 weeks in the SW9 group, and soluble CD8 and beta2-microglobulin remained elevated at 3 months. Therefore, measles immunization resulted in suppression of lymphoproliferation, which was most evident in infants with the highest antibody responses and most immune activation.

Pertussis deaths: report of 23 cases in the United States, 1992 and 1993

OBJECTIVE

To characterize pertussis deaths and to identify possible risk factors and prevention strategies.

METHODS

A retrospective review of all deaths attributed to pertussis with disease onset during 1992 and 1993 reported to the Centers for Disease Control and Prevention. Hospital discharge summaries and autopsy reports were reviewed, and additional clinical information was provided by physicians involved in the care of the children.

RESULTS

During 1992 and 1993, 23 deaths attributed to pertussis were reported to the Centers for Disease Control and Prevention. Cultures for Bordetella pertussis were positive in 18 (90%) of the 20 cases in which it was performed. Twenty (87%) of the 23 children who died were young than 1 year of age, and 18 (78%) of the children had received no doses orf pertussis vaccine. Among 20 children for whom gestational ages were known, 12 (60%) were born at36 weeks' gestation or earlier; in contrast, 10.7% of live births in the United States in 1992 were at 36 weeks' gestation or earlier. The median age of mothers whose children had fatal pertussis was 20 (range, 14 to 37) years in the 15 cases in which ages were known, compared with the national median age of 26.3 years in 1992. Pneumonia was a complication in all but 1 (96%) of the cases. Seizures occurred in 4 cases (17%), and acute encephalopathy occurred in 3 cases (13%).

CONCLUSIONS

Pertussis continues to cause serious illness and death in the United States, particularly among infants who are not vaccinated. Preterm delivery and young maternal age may place infants at increased risk of death because of pertussis. Under the current pertussis vaccination schedule, three fourths of the infants who died were too young to have received three doses of pertussis vaccine, the minimum number of doses considered necessary for adequate protection against clinical pertussis. Additional strategies, to prevent deaths caused by pertussis in young infants, such as starting infant vaccination at an earlier age and booster doses to adolescents and adults, need to be evaluated.

Changes within T cell receptor V beta subsets in infants following measles vaccination

Measles produces immune suppression which contributes to an increased susceptibility to other infections. Recently, high titered measles vaccines have been linked to increased long-term mortality among some female recipients. Because the mechanisms by which wild-type or attenuated live-vaccine strains of measles virus alter subsequent immune responses are not fully understood, this prompted an examination of the changes within the peripheral blood T cell receptor V beta repertoire following measles immunization. Twenty-four 6- and 9-month-old infants were studied at 2 weeks and 3 months following immunization by semiquantitative reverse transcription-polymerase chain reaction. There was a significant increase in V beta 2 expression (P less than 0.05), and a decrease in the V beta 4 subset (P less than 0.03) 2 weeks following vaccination with subsequent return to baselines at 3 months in vaccine recipients who seroconverted. These data suggest that measles virus may affect immune responses in part by altering the T cell receptor repertoire.

Risk factors for pertussis in young infants during an outbreak in Chicago in 1993

Because young infants are at highest risk for severe pertussis and death and are also too young to have received the minimal protective series of three doses of diphtheria-tetanus-pertussis (DTP) vaccine, we conducted a matched case-control study to assess risk factors for pertussis among young infants during a pertussis outbreak in Chicago in 1993. We enrolled 39 cases < 7 months of age from a single teaching hospital and 96 controls, individually matched for age, from the well-child clinic at the same hospital. Demographic characteristics, immunization status, and opportunities for disease exposure were analyzed by means of conditional logistic regression. Cases and controls were similarly up to date with their DTP vaccinations (87% and 89%, respectively). Infants of adolescent mothers (matched odds ratio [OR], 6.4; 95% confidence interval [CI], 1.3-41.4) and infants of mothers who suffered > or = 7 days of cough during the child's incubation period (matched OR, 12.0; 95% CI, 1.4 to infinity) were significantly more likely to have pertussis. Young mothers and mothers with a cough lasting > or = 7 days may be an important source of pertussis infection for their young infants.

Vaccine-associated paralytic poliomyelitis in the United States: no evidence of elevated risk after simultaneous intramuscular injections of vaccine

During the past 30 years, Romania reported rates of vaccine-associated paralytic poliomyelitis (VAPP) approximately 10-fold higher than in the United States. The elevated VAPP risk was largely caused by multiple intramuscular (im) injections with antibiotics given within 30 days of onset of paralysis. Because it is not known whether im injections contribute to the VAPP risk in the United States, we examined VAPP cases reported since 1980. We reviewed injection histories of VAPP cases reported to the Centers for Disease Control and Prevention from 1980 to 1993: with vaccines for 1980 to 1987; and for all substances for 1988 to 1993. Rates of VAPP by number of im injections with vaccines were calculated from 1988 to 1993 with estimated vaccine coverage data from the National Health Interview Survey. From 1980 to 1993 a total of 119 cases of poliomyelitis were reported to the Centers for Disease Control and Prevention. Of these, 87 (73%) were vaccine-associated and immunologically normal: 41 were oral polio vaccine (OPV) recipient cases; 40 were OPV contact cases; and 6 were community-acquired cases. A history of im injections in the 45 days before onset of paralysis was obtained from 28 (72%) of 39 recipient cases reported from 1980 to 1993 for which dates of paralysis onset could be determined and from 1 (8%) of 13 contact cases reported from 1988 to 1993. With one exception all substances administered intramuscularly were routine childhood vaccines. No clustering of im injections in the "high risk" windows, 0 to 3 and 8 to 21 days before onset of paralysis, was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Concurrent outbreaks of pertussis and Mycoplasma pneumoniae infection: clinical and epidemiological characteristics of illnesses manifested by cough

Concurrent outbreaks of illnesses that were manifested by cough and that were suspected to be due to Bordetella pertussis and Mycoplasma pneumoniae infection were investigated in a midwestern town in Illinois. Three studies were conducted: questionnaires on the clinical and epidemiological characteristics of illness were administered to patients; serological tests were performed to confirm the presence of each pathogen and to develop case definitions for each illness; and case definitions were applied to responses to a mail-in questionnaire for estimating the magnitude of both outbreaks. In 135 cases of suspected pertussis and 42 cases of suspected mycoplasmal infection, subjects had a cough for > or = 14 days (the pertussis outbreak case definition). Among 20 laboratory-confirmed cases, a cough for > or = 14 days had a specificity of 20% for pertussis, and a cough for > or = 28 days plus whoop and/or vomiting had a specificity of 90% for pertussis. Six hundred-seventeen pertussis cases per 100,000 population and 1,179 cases of M. pneumoniae infection per 100,000 population occurred. In this setting, the standard outbreak case definition for pertussis lacked adequate specificity to distinguish pertussis from mycoplasmal infection. The magnitude of each outbreak was greater than the number of reported cases suggested.

Intramuscular injections within 30 days of immunization with oral poliovirus vaccine--a risk factor for vaccine-associated paralytic poliomyelitis

BACKGROUND

In Romania the rate of vaccine-associated paralytic poliomyelitis is for unexplained reasons 5 to 17 times higher than in other countries. Long ago it was noted that intramuscular injections administered during the incubation period of wild-type poliovirus infection increased the risk of paralytic disease (a phenomenon known as "provocation" poliomyelitis). We conducted a case-control study to explore the association between intramuscular injections and vaccine-associated poliomyelitis in Romania.

METHODS

The patients were 31 young children in whom vaccine-associated paralytic poliomyelitis developed from 1988 through 1992. Eighteen were vaccine recipients, and 13 had acquired the disease by contact with vaccine recipients. Each of these children was matched with up to five controls according to health center, age, and in the case of vaccine recipients, history of receipt of the live attenuated oral poliovirus vaccine. Data were abstracted from medical records that documented the injections administered in the 30 days before the onset of paralysis.

RESULTS

Of the 31 children with vaccine-associated disease, 27 (87 percent) had received one or more intramuscular injections within 30 days before the onset of paralysis, as compared with 77 of the 151 controls (51 percent) (matched odds ratio, 31.2; 95 percent confidence interval, 4.0 to 244.2). Nearly all the intramuscular injections were of antibiotics, and the association was strongest for the patients who received 10 or more injections (matched odds ratio for > or = 10 injections as compared with no injections, 182.1; 95 percent confidence interval, 15.2 to 2186.4). The risk of paralytic disease was strongly associated with injections given after the oral polio virus vaccine, but not with injections given before or at the same time as the vaccine (matched odds ratio, 56.7; 95 percent confidence interval, 8.9 to infinity). The attributable risk in the population for intramuscular injections given in the 30 days before the onset of paralysis was 86 percent (95 percent confidence interval, 66 to 95 percent); that is, we estimate that 86 percent of the cases of vaccine-associated paralytic poliomyelitis in this population might have been prevented by the elimination of intramuscular injections within 30 days after exposure to oral poliovirus vaccine.

CONCLUSIONS

Provocation paralysis, previously described only for wild-type poliovirus infection, may rarely occur in a child who receives multiple intramuscular injections shortly after exposure to oral poliovirus vaccine, either as a vaccine recipient or through contact with a recent recipient. This phenomenon may explain the high rate of vaccine-associated paralytic poliomyelitis in Romania, where the use of intramuscular injections of antibiotics in infants with febrile illness is common.

Risk of vaccine-associated paralytic poliomyelitis in Latin America, 1989-91

A major factor influencing the success of poliomyelitis eradication in the Americas was the reliance on mass immunization campaigns with oral poliovirus vaccine (OPV). As global poliomyelitis eradication activities accelerate and campaign vaccine delivery strategies are applied elsewhere, it is critical to determine whether the risk of vaccine-associated paralytic poliomyelitis (VAPP) is altered when routine delivery strategies are supplemented with mass immunization campaigns. We analysed all 6043 cases of acute flaccid paralysis (AFP) reported in Latin America over the period 1989-91 in order to estimate the risk of VAPP. The overall risk was estimated to be one case per 1.5-2.2 million doses of OPV administered, compared with one case per 1.4 million doses administered in England and Wales (1985-91) and with one case per 2.5 million net doses distributed in the USA (1980-89). These data suggest that to eradicate poliomyelitis globally, strategies that rely on mass immunization campaigns to supplement routine delivery services, as recommended by WHO, do not appear to alter significantly the risk of VAPP.

Paralytic poliomyelitis in Romania, 1984-1992. Evidence for a high risk of vaccine-associated disease and reintroduction of wild-virus infection

Although poliomyelitis due to wild-virus infection has virtually disappeared from Romania, with no cases having been documented between 1984 and 1989, vaccine-associated paralytic poliomyelitis has been reported at very high rates for over two decades. In November 1990, to decrease the risk of vaccine-associated paralytic poliomyelitis, oral poliovirus vaccine produced in Romania was replaced by imported oral vaccine made by a Western European manufacturer. To better quantify the risk of vaccine-associated paralytic poliomyelitis and the impact of the change in vaccine manufacturer, the authors reviewed clinical, epidemiologic, and laboratory data on poliomyelitis cases that occurred in Romania from 1984 to 1992. Poliovirus isolates were characterized at the US Centers for Disease Control and Prevention. During the period 1984-1992, 132 confirmed cases of paralytic poliomyelitis were reported in Romania, of which 13 were classified as wild-virus-associated, 93 as vaccine-associated, and 26 as "of unknown origin." Wild type 1 poliovirus was isolated during 1990-1992 from nine of 13 (69%) cases in an outbreak that occurred primarily among undervaccinated gypsy children. Vaccine-associated cases were epidemiologically and virologically distinct from wild-virus cases. Of the 93 vaccine-associated cases, 45 children were recipients and 48 were contacts. The overall risk of vaccine-associated paralytic poliomyelitis in Romania (1 case per 183,000 doses of oral poliovirus vaccine distributed) was 14-fold higher than the risk in the United States. The risks of recipient vaccine-associated paralytic poliomyelitis related to the first dose of oral vaccine were similar for Romanian and imported vaccine (1 case per 95,000 doses and 1 case per 65,000 doses, respectively), as were the total risks of vaccine-associated paralytic poliomyelitis. These findings definitively demonstrate a substantially elevated risk of vaccine-associated paralytic poliomyelitis in Romania which was not affected by a change in oral poliovirus vaccine manufacturer.

Completeness of reporting for paralytic poliomyelitis, United States, 1980 through 1991. Implications for estimating the risk of vaccine-associated disease

BACKGROUND

Although the risk of vaccine-associated paralytic poliomyelitis (VAPP) has remained relatively constant during the past 30 years, estimates of VAPP depend largely on the completeness of reporting to the existing passive surveillance system. The National Vaccine Injury Compensation Program constitutes an alternative system for reporting VAPP, and data available from this system permitted us to evaluate the completeness of the national poliomyelitis surveillance system.

METHODS

We compared cases of paralytic poliomyelitis reported to the national surveillance system (maintained by the Centers for Disease Control and Prevention, Atlanta, Ga) with cases recommended for compensation by the National Vaccine Injury Compensation Program, Rockville, Md, and we calculated the observed completeness of reporting to the national system for 1980 through 1991. A capture-recapture method was also used to estimate completeness of reporting, ie, to account for cases potentially missed by both systems. In addition, we reviewed the epidemiology and updated the risk of VAPP based on the most current information on cases of VAPP.

RESULTS

From 1980 through 1991, 105 cases of paralytic poliomyelitis were identified by the Centers for Disease Control and Prevention and National Vaccine Injury Compensation Program systems, 98 (93%) of which were VAPP (average, 8.2 cases per year). The observed completeness of reporting to the Centers for Disease Control and Prevention was 94%, and the estimated completeness of reporting (capture-recapture method) was 81%. The overall risk of VAPP was one case per 2.5 million doses of oral poliovirus vaccine distributed. In the sensitivity analysis, the risk estimates of VAPP remained relatively stable throughout a wide range of assumptions regarding underreporting and specificity of the case definition for paralytic poliomyelitis.

CONCLUSION

The risk of VAPP remains virtually unchanged from previous estimates despite the inclusion of previously unidentified VAPP cases. Despite the potential for both underreporting and misclassification of cases, our risk estimates were relatively insensitive to either of these biases. Since both of these biases were in opposite directions, and both probably occurred with low frequency, the risk estimates provided in this report appear valid and approximate the "true" risk of VAPP in the United States.

Reporting efficiency during a measles outbreak in New York City, 1991

OBJECTIVES

During an epidemic of measles among preschool children in New York City, an investigation was conducted in 12 city hospitals to estimate reporting efficiency of measles to the New York City Department of Health.

METHODS

Measles cases were identified by review of hospital emergency room and infection control logs and health department surveillance records. The Chandra Sekar Deming method was used (1) to estimate the total number of measles cases in persons less than 19 years old who presented to the 12 hospitals from January through March 1991 and (2) to estimate reporting efficiency. Information on mechanisms for reporting measles cases was collected from hospital infection control coordinators.

RESULTS

The Chandra Sekar Deming method estimated that 1487 persons with measles presented to the 12 hospitals during the study period. The overall reporting efficiency was 45% (range = 19% to 83%). All 12 hospitals had passive surveillance for measles; 2 also had an active component. These 2 hospitals had the first and third highest measles reporting efficiencies.

CONCLUSIONS

The reporting efficiency of measles cases by New York City hospitals to the health department was low, indicating that the magnitude of the outbreak was substantially greater than suggested by the number of reported cases.

Pertussis in Missouri: evaluation of nasopharyngeal culture, direct fluorescent antibody testing, and clinical case definitions in the diagnosis of pertussis

No diagnostic test for pertussis in routine use in the United States has both high sensitivity and high specificity. During a statewide increase in the incidence of pertussis in Missouri, we studied the clinical features of 153 patients with suspected pertussis in the Greater St. Louis area from whom a specimen for pertussis culture had been taken between 15 May and 19 September 1989. In this cross-sectional study, nasopharyngeal cultures were more likely to be positive for persons whose specimens were collected < 21 days after cough onset (adjusted rate ratio [RRa] and 95% confidence interval = 3.4; 1.5-8.0) and who were not receiving erythromycin/sulfamethoxazole prior to the culture [RRa = 5.8; 0.8-40.6], who had received fewer than three prior doses of pertussis vaccine [RRa = 1.8; 0.8-4.2], and whose specimen was in transit to the laboratory for < 4 days [RRa = 2.0; 0.8-5.5]. Among children < 5 years of age, spasmodic cough plus a lymphocytosis of > 10,000/mm3 was the acute symptom complex associated with the highest predictive value for a positive culture result (67%). Cough for > or = 14 days plus whoop was sensitive (81%) and specific (58%) for identifying children with culture-confirmed pertussis. Direct fluorescent antibody staining performed well as a screening test for pertussis but requires substantial commitment of personnel and resources. In the absence of a positive culture result, clinical case definitions should be used for decision making (e.g., initiation of antimicrobial therapy and routine case reporting).

Fatal respiratory disease due to Corynebacterium diphtheriae: case report and review of guidelines for management, investigation, and control

Dramatic reductions in the incidence of diphtheria and high levels of childhood vaccination in recent decades have led the United States to establish the goal of diphtheria elimination among persons < or = 25 years of age by the year 2000. In 1990, an unimmunized 25-month-old child died of respiratory diphtheria in Dade County, Florida, before treatment with diphtheria antitoxin could be instituted. Twenty-three asymptomatic household contacts and other close contacts of the child were identified, cultured for Corynebacterium diphtheriae, given antimicrobial prophylaxis, and vaccinated with diphtheria toxoid when indicated. Three contacts (13%) had pharyngeal cultures positive for toxigenic C. diphtheriae of the same type as that causing infection in the deceased child, but no additional cases developed. Although the source of infection was not determined, three other close contacts had recently been to Haiti, where diphtheria is endemic. A serological survey of 396 children < 5 years of age who received care at a medical center in Dade County revealed that 22% lacked protective immunity to diphtheria. Attainment of the goal of diphtheria elimination among persons < or = 25 years of age--and ultimately among all persons--will depend on the maintenance of a high level of clinical awareness of the disease, the prompt institution of preventive measures among close contacts of patients with sporadic cases, and improved vaccination levels among infants, children, and adults.

Pertussis surveillance--United States, 1989-1991

The licensure of whole-cell pertussis vaccine combined with diphtheria and tetanus toxoids as DTP in the 1940s--and its widespread use in infants and children--led to a dramatic decline in the incidence of reported pertussis. In the prevaccine era, the average annual incidence and mortality for reported pertussis were 150 cases and six deaths per 100,000 population, respectively. From 1989 to 1991, pertussis cases were reported by state and local health departments to CDC through two distinct national surveillance systems: the National Notifiable Diseases Surveillance System (NNDSS) and the Supplementary Pertussis Surveillance System (SPSS). During the period 1989-1991, 11,446 pertussis cases were reported to the NNDSS (4,157 in 1989; 4,570 in 1990; and 2,719 in 1991), for an unadjusted annual incidence of 1.7, 1.8, and 1.1 cases per 100,000 population in 1989, 1990, and 1991, respectively. For the period 1989-1991, case reports were received through the SPSS on 9,480 (83%) of the 11,446 patients reported to the NNDSS. Age-specific incidence and hospitalization rates were highest among children < 1 year of age and declined with increasing age. Long-term trends suggest an increase in the reported incidence of pertussis in the United States since 1976. The peak in reported pertussis cases in 1990 represents the highest annual incidence of pertussis since 1970. However, the incidence of pertussis declined 41% from 1990 through 1991. Whether the long-term increase in reported pertussis is a true increase in incidence is unclear; the observed increase may be a function of improved surveillance.(ABSTRACT TRUNCATED AT 250 WORDS)

Tetanus surveillance--United States, 1989-1990

During the period 1989-1990, 117 cases of tetanus were reported from 34 states, for an average annual incidence of 0.02/100,000 population. Fifty-eight percent of patients were > or = 60 years of age, while seven (6%) were < 20 years of age, including one case of neonatal tetanus. Among adults, the risk of tetanus in those > 80 years of age was more than 10 times the risk in persons ages 20-29 years. The case-fatality rate increased with age, from 17% in persons 40-49 years of age to 50% in those > or = 80 years of age. Only 11% of patients reported having received a primary series of tetanus toxoid before disease onset, while 31% lacked a history of tetanus vaccination. Tetanus occurred following an acute injury in 78% of patients. Of patients who sought medical care, only 58% received tetanus toxoid as part of wound prophylaxis. Tetanus remains a severe disease that primarily affects unvaccinated or inadequately vaccinated older adults. Increased efforts are needed to reduce the risk of tetanus among the elderly. Health-care providers should take every opportunity to review the vaccination status of their patients and provide tetanus vaccine when indicated.

Childhood tuberculosis and tuberculous meningitis: high incidence rates in the Western Cape of South Africa

In recent years higher incidence rates of tuberculosis (TB) have been reported from the Western Cape than from other health regions of South Africa. In contrast to the various pulmonary forms of tuberculosis, tuberculous meningitis (TBM) always requires hospital admission, and can thus be used as an indicator of the extent of the infection in a community, as well as providing a measure of the effectiveness of primary and secondary preventive measures. In the present study an attempt was made to identify all cases of tuberculous meningitis aged 14 years and younger which occurred in the region, by checking notifications and the records of all hospitals, and verifying diagnosis against set criteria. Rates for the entire period were calculated according to updated census data. There was a total of 689 confirmed cases, of which only 55% had been notified. Of the 238 cases confirmed in the 3-years period, 1985-1987, 25.2% were under 1 year, 51.7% under 2 years, and 79.8% under 5 years of age. Age-specific incidence per 100,000 children were respectively 31.5 (0-1 years), 17.1 (1-4 years), 4.8 (5-9 years), and 0.7 (10-14 years). Rates in rural areas were far higher than in metropolitan regions. Utilizing tuberculin test data and total notifications, the following risks could be calculated for 'Coloured' children (of mixed race) aged 0-4 years: 2-3% annual risk of infection; 15.7% risk of TB in infected population; 0.5% risk of TBM in infected population; 0.9% risk of TB in children aged 5-14 years; 0.01% risk of TBM in children aged 5-14 years.

Epidemiology of poliomyelitis in the United States one decade after the last reported case of indigenous wild virus-associated disease

Poliomyelitis caused by wild poliovirus has been virtually nonexistent in the United States since 1980, and vaccine-associated paralytic poliomyelitis (VAPP) has emerged as the predominant form of the disease. We reviewed national surveillance data on poliomyelitis for 1960-1989 to assess the changing risks of wild-virus, vaccine-associated, and imported paralytic disease; we also sought to characterize the epidemiology of poliomyelitis for the period 1980-1989. The risk of VAPP has remained exceedingly low but stable since the mid-1960s, with approximately 1 case occurring per 2.5 million doses of oral poliovirus vaccine (OPV) distributed during 1980-1989. Since 1980 no indigenous cases of wild-virus disease, 80 cases of VAPP, and five cases of imported disease have been reported in the United States. Three distinct groups are at risk of vaccine-associated disease: recipients of OPV (usually infants receiving their first dose), persons in contact with OPV recipients (mostly unvaccinated or inadequately vaccinated adults), and immunologically abnormal individuals. Overall, 93% of cases in OPV recipients and 76% of vaccine-associated cases have been related to administration of the first or second dose of OPV. Our findings suggest that adoption of a sequential vaccination schedule (inactivated poliovirus vaccine followed by OPV) would be effective in decreasing the risk of VAPP while retaining the proven public health benefits of OPV.

Effect of stress on birth weight in two Johannesburg populations

The effect of stress on birth weight was assessed in mothers delivering at Johannesburg (predominantly white) and Baragwanath (exclusively black) Hospitals. The Social Readjustment Rating Scale of Holmes and Rahe was used to assign maternal stress scores established during an interview conducted within 36 hours of delivery. Only mothers without medical problems who had delivered liveborn infants were included. Maternal age, obstetric history, smoking history and stresses present during the 12 months preceding delivery were recorded. Of 535 Johannesburg and 662 Baragwanath mothers studied, 48% and 55% respectively reported significant stresses. Analysis of the two groups revealed that for the Johannesburg mothers, smoking, cumulative stress score and previous preterm birth were important determinants of birth weight. Of the stress factors studied, marital separation and death of a spouse were significantly associated with a lower birth weight. For Baragwanath mothers the major determinants of low birth weight were maternal age, loss of income through being dismissed from work, or having to leave school as a consequence of the pregnancy.

Utilisation of outpatient services at Red Cross War Memorial Children's Hospital, Cape Town

The demand for outpatient services continues to grow at Red Cross War Memorial Children's Hospital (RCCH). To determine current utilisation patterns, we conducted a 2-week survey in the outpatient department (OPD). In addition, we reviewed the RCCH Annual Reports for the period 1961-1988. Annual outpatient attendances have increased from around 42,000 in 1957 to their highest level ever; nearly 350,000 in 1988. This steady rise in outpatient attendance was stemmed during the 1970s by the expansion of health services in the greater Cape Town area, in particular the introduction of day hospitals. In general, blacks are utilising the OPD as a primary community hospital for the treatment of infectious and environmentally induced diseases. In contrast, the white outpatient profile is more characteristic of a tertiary referral centre, with a higher proportion of specialist clinic attendances. The utilisation patterns for coloured children are intermediate. Analysis of the residential address of patients and their presenting diagnoses indicates an urgent demand for primary health care services in the most recently settled and poorest suburbs of Cape Town, many of which are remote from the hospital.