Muireann Brennan

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.

Evidence for Transmission of Pertussis in Schools, Massachusetts, 1996: Epidemiologic Data Supported by Pulsed-Field Gel Electrophoresis Studies

In 1996, 18 of 20 pertussis outbreaks reported in Massachusetts occurred in schools. Pertussis surveillance data were reviewed and a retrospective cohort study was conducted in a high school that experienced an outbreak. Bordetella pertussis isolates from 9 school cases and from 58 cases statewide were examined by use of pulsed-field gel electrophoresis (PFGE). Statewide incidence rates were highest among children aged <1 year, 10-14 years, and 15-19 years (106, 117, and 104 cases per 100,000, respectively). Among 34 confirmed and 20 probable cases at the school, 61% had cough onset within 8 weeks of school opening. Five different PFGE types were identified among the 58 B. pertussis isolates from throughout the state. All 9 isolates from the affected high school were the same PFGE type. School-aged children may play an important role in pertussis epidemics. Consideration should be given to use of acellular pertussis vaccines among school-aged children.

Pertussis outbreak in an elementary school with high vaccination coverage.

BACKGROUND An outbreak of pertussis in a US elementary school with high vaccination coverage was investigated to evaluate vaccine effectiveness and to identify potential contributing factors. METHODS Survey and cohort study of all 215 students of an elementary school (including 36 case patients) and 16 secondary cases among contacts. RESULTS Fifty-two pertussis cases were identified (attack rate among students, 17%). Receipt of <3 doses of pertussis-containing-vaccine compared with receipt of complete vaccination series was a significant risk factor for pertussis [relative risk, 5.1; 95% confidence interval (CI), 3 to 8.6]. The effectiveness of the complete vaccination series was 80% (95% CI 66 to 88). No evidence of waning immunity among students was found. The following contributing factors for the outbreak were identified: multiple introductions of pertussis from the community; delays in identification and treatment of early cases; and high contact rates among students. Antimicrobial treatment initiated >14 days after cough onset was associated with increased risk of further transmission of pertussis (relative risk, 10.1; 95% CI 1.5 to 70.3) compared with treatment within 14 days of onset. CONCLUSIONS This investigation demonstrated the potential for pertussis outbreaks to occur in well-vaccinated elementary school populations. Aggressive efforts to identify cases and contacts and timely antimicrobial treatment can limit spread of pertussis in similar settings. High vaccination coverage should be maintained, because vaccination significantly reduces the risk of the disease throughout the elementary school years, and to ensure timely diagnosis and treatment health care providers should maintain a high index of suspicion for pertussis among elementary school age children.

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.

Vaccine-preventable diseases in humanitarian emergencies among refugee and internally-displaced populations

Humanitarian emergencies may result in breakdown of regular health services including routine vaccination programs. Displaced populations including refugees and internally displaced persons are particularly susceptible to outbreaks of communicable diseases such as vaccine-preventable diseases (VPDs). Common VPDs encountered in humanitarian emergencies include measles, polio, and depending on geographical location, meningococcal meningitis, yellow fever, hepatitis A, and cholera. We conducted a review of 50 published articles from 2000 to 2015 concerning VPDs in humanitarian emergencies. This article provides an update on the available literature regarding vaccinations among this highly vulnerable population and describes the unique challenges of VPDs during humanitarian emergencies. Humanitarian emergencies place affected populations at risk for elevated morbidity and mortality from VPDs due to creation or exacerbation of factors associated with disease transmission such as mass population movements, overcrowding, malnutrition, and poor water and sanitation conditions. Vaccination is one of the most basic and critical health interventions for protecting vulnerable populations during emergencies. Growing insecurity, as seen in the increasing number of targeted attacks on health workers in recent years, as well as destruction of cold chain and infrastructure for transportation of supplies, are creating new challenges in provision of life saving vaccines in conflict settings. Population displacement can also threaten global VPD eradication and elimination efforts. While highly effective vaccines and guidelines to combat VPDs are available, the trend of increasing number of humanitarian emergencies globally poses new and emerging challenges in providing vaccination among displaced populations.

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 20–49 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.

Injuries and deaths caused by unexploded ordnance in afghanistan: review of surveillance data, 1997-2002

In 2000-2, Afghanistan had the highest number of casualties due to landmines and unexploded ordnance in the world.1 Increasing international awareness of the public health threat posed by landmines is the legacy of the International Campaign to Ban Landmines. More attention must be paid to the growing and equally deadly threat posed by unexploded ordnance. We reviewed the surveillance database on injuries due to unexploded ordnance and landmines maintained by the United Nations Mine Action Center for Afghanistan. About 70% of records in the database came from the clinic based surveillance system operated by the International Committee of the Red Cross, which, in 2002, included 390 health facilities.2 Other data were collected through mine clearance teams, education programmes to minimise the risks posed by mines, and programmes to help victims. We excluded duplicate entries by comparing the demographics, time, and location of injury of the victim. We used JMP …

Implementation of a Mass Measles Campaignin Central Afghanistan, December 2001to 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.

How Many Doses of Diphtheria Toxoid Are Required for Protection in Adults? Results of a Case-Control Study among 40- to 49-Year-Old Adults in the Russian Federation

During the Russian diphtheria epidemic of the 1990s, adults had an unexpectedly high rate of disease. A retrospective, matched case-control study was done to measure the effectiveness of one, two, or three or more doses of diphtheria toxoid against diphtheria among 40- to 49-year-old Russians. Thirty-nine diphtheria case-patients and 117 controls were studied. Previous vaccinations were included if one dose was received within the previous 10 years. Five cases (13%) and 33 controls (28%) had received three or more doses of vaccine. The matched odds ratio was 0.3 (95% confidence interval, 0.1-0.9) for three or more doses compared with no doses, which was a vaccine effectiveness of 70% (95% confidence interval, 10-90). A trend existed toward milder disease with increasing doses (chi2 test for trend, P=.02). The results suggest that Russian adults, who were unlikely to have acquired immunity to diphtheria through immunization or natural infection, required at least three doses of diphtheria toxoid for reliable protection against disease.

The lasting legacy of war: epidemiology of injuries from landmines and unexploded ordnance in Afghanistan, 2002-2006

INTRODUCTION Due to several decades of armed conflict and civil unrest, Afghanistan is one of the countries most affected by landmines and unexploded ordnance worldwide. OBJECTIVE The study was performed to assess the magnitude of injuries due to landmines and unexploded ordnance in Afghanistan during 2002-2006 and to describe epidemiological patterns and potential risk factors for these events. METHODS Surveillance data including 5,471 injuries caused by landmines and unexploded ordnance in Afghanistan during 2002-2006 were analyzed. The International Committee of the Red Cross collects data on such injuries from 490 reporting health facilities and volunteers throughout the country. These surveillance data were used to describe injury trends, victim demographics, injury types, risk behaviors, and explosive types related to landmine and unexploded ordnance accidents. RESULTS The largest number of injuries (1,706) occurred in 2002. The number declined sharply to 1,049 injuries in 2003, and remained relatively stable with slight decline thereafter. Overall, 92% of victims were civilians, 91% were males, and 47% were children <18 years of age. The case-fatality ratio was 17%. Approximately 50% of all injuries were caused by unexploded ordnance and 42% by landmines. Among children, 65% of injuries were caused by unexploded ordnance and only 27% by landmines, whereas in adults, most injuries (56%) were caused by landmines. The most common risk behaviors among children were tending animals, playing, and tampering with explosive devices. In adults, most common risk behaviors were traveling, performing activities of economic necessity, and tampering with explosives. Twenty-eight percent of the surviving victims who received mine awareness training and 2% of those who did not receive such training reported that the area where event occurred was marked. CONCLUSIONS The large number of injuries and high proportion of child victims suggest that clearance and risk education activities fall short of achieving their goals, and must be substantially improved or expanded. Especially concerning is the high proportion of injuries caused by unexploded ordnance, and the high number of injuries sustained while tampering with explosive devices. Because unexploded ordnance is more visible than are landmines, and ordnance-contaminated areas are cheaper to clear than are minefields, these injuries are highly preventable and should be a priority for clearance and risk education efforts.