D. Rebecca Prevots

Field Applicability of a Rapid-Format Anti–Ov-16 Antibody Test for the Assessment of Onchocerciasis Control Measures in Regions of Endemicity

BACKGROUND A previously developed, specific, rapid-format immunochromatographic card test that detects immunoglobulin G4 to the recombinant Onchocerca volvulus antigen Ov-16 was modified to detect antibodies in whole blood. METHODS Ov-16 card test results were assessed in 1511 subjects > or =2 years of age in 7 West African villages with varying histories of onchocerciasis control measures. RESULTS In villages in which control measures had been implemented, anti-Ov-16 antibody prevalence rates ranged from 5.2% to 65.1%. Antibody prevalence rates were close to zero among subjects born after effective control measures had been implemented. In 2 villages without a history of control measures where onchocerciasis was endemic, microfilariae (MF) prevalence rates were 82.8% and 65.1%, and antibody prevalence rates were 73.1% and 62.1%. In these 2 villages, the sensitivity of the Ov-16 card test was 81.1% and 76.5%, the specificity was 100%, and the positive predictive value was 91.8% and 80.5%. MF and antibody prevalence rates were correlated (Spearmans r=0.815; P<.038). CONCLUSIONS The Ov-16 card test is field applicable, exhibits high sensitivity and specificity for O. volvulus infection, and has great potential as a tool for surveillance and for evaluating the success of onchocerciasis control measures.

Outbreak of Paralytic Poliomyelitis in Albania, 1996: High Attack Rate Among Adults and Apparent Interruption of Transmission Following Nationwide Mass Vaccination

After >10 years without detection of any cases of wild virus-associated poliomyelitis, a large outbreak of poliomyelitis occurred in Albania in 1996. A total of 138 paralytic cases occurred, of which 16 (12%) were fatal. The outbreak was due to wild poliovirus type 1, isolated from 69 cases. An attack rate of 10 per 100,000 population was observed among adults aged 19-25 years who were born during a time of declining wild poliovirus circulation and had been vaccinated with two doses of monovalent oral poliovirus vaccines (OPVs) that may have been exposed to ambient temperatures for prolonged periods. Control of the epidemic was achieved by two rounds of mass vaccination with trivalent oral poliovirus vaccine targeted to persons aged 0-50 years. This outbreak underscores the ongoing threat of importation of wild poliovirus into European countries, the importance of delivering potent vaccine through an adequate cold chain, and the effectiveness of national OPV mass vaccination campaigns for outbreak control.

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.

Interruption of Measles Transmission in Brazil, 2000–2001

In 1992, Brazil adopted the goal of measles elimination by the year 2000; however, in 1997, after a 4-year period of good control, there was a resurgence of measles in Brazil. In 1999, to achieve the elimination goal, Brazil implemented the Supplementary Emergency Measles Action plan, with one measles surveillance technician designated to each state. Of 10,007 suspected measles cases reported during 1999, 908 (9.1%) were confirmed, and of them 378 (42%) were confirmed by laboratory analysis. Of 8358 suspected measles cases reported in 2000, 36 (0.4%) were confirmed (30 [83%] by laboratory); 92% of the discarded cases were classified on the basis of laboratory testing. In 2001, only 1 of 5599 suspected measles cases was confirmed, and it was an imported case from Japan. The last outbreak occurred in February 2000, with 15 cases. Current data suggest interruption of indigenous measles transmission in Brazil.

Burden of congenital rubella syndrome after a community-wide rubella outbreak, Rio Branco, Acre, Brazil, 2000 to 2001

Background. During 1999 and 2000 rubella outbreaks were reported in 20 of 27 states in Brazil, many among young adults. We investigated a large rubella outbreak in Rio Branco, Acre, in northwestern Brazil, where rubella vaccination targeting children 1 to 11 years old had been introduced in April 2000. Surveillance for congenital rubella syndrome (CRS) was initiated after the outbreak. Methods. Suspected rubella cases were detected through active and passive surveillance. Confirmed rubella cases were patients with fever, rash and rubella-specific IgM antibodies. Suspected CRS cases were infants born with CRS-compatible defects or born to mothers with a history of rubella during pregnancy. Confirmed cases were infants with CRS-compatible defects and rubella-specific IgM antibodies. Results. From April 1 to December 31, 2000, 391 confirmed rubella cases were reported. The incidence among persons ages 12 to 19 years (3.3 per 1000 population) was increased 3.7-fold relative to children ages 1 to 4 years (95% confidence interval, 2.4 to 5.8). Of 21 infants with suspected CRS cases, 17 (91%) were tested for rubella-specific antibodies, of whom 7 were IgM-positive and 5 had confirmed CRS. The peak incidence of confirmed CRS (4.3 per 1000) was in March 2001, 7 months after the outbreak peak, with an annualized incidence of 0.6 per 1000. Conclusions. Vaccination among school age children was insufficient to prevent a rubella outbreak among young adults that resulted in the occurrence of at least 5 cases of CRS. To prevent further cases of CRS, outbreak vaccination of young adults was conducted in November 2000 and among women ages 12 to 39 years in 2001 as part of a national campaign, with a coverage of 98% statewide.

Incidence of HIV Among Injection Drug Users Entering Drug Treatment Programs in Four US Cities

We estimated seroincidence of human immunodeficiency virus (HIV) and prevalence of risk behaviors among injection drug users (IDUs) who accepted voluntary HIV testing on entry to drug treatment. Record-based incidence studies were conducted in 12 drug treatment programs in New York City (n = 890); Newark, New Jersey (n = 521); Seattle, Washington (n = 1,256); and Los Angeles, California (n = 733). Records of confidential HIV tests were abstracted for information on demographics, drug use, and HIV test results. More detailed data on risk behaviors were obtained by a standardized questionnaire. Although overall incidence rates were relatively low in this population (<1/100 person-years), there was a high prevalence of risk behaviors. Needle sharing was reported by more than one-third of the participants in each of the cities. HIV seroincidence rates were up to three-fold higher among younger ID Us. We found that HIV continued to be transmitted among ID Us who had received both drug treatment and HIV counseling and testing. HIV/AIDS (acquired immunodeficiency syndrome) prevention education should continue to be an important component of drug treatment.

Poliovirus vaccines. Progress toward global poliomyelitis eradication and changing routine immunization recommendations in the United States.

Poliomyelitis prevention in the United States has relied virtually exclusively on OPV during the past 30 years. Starting in 1997, a major change in the poliomyelitis vaccination policy occurred, facilitated by substantial progress toward worldwide poliomyelitis eradication. A sequential schedule of IPV followed by OPV became the preferred means to prevent poliomyelitis, although an all-OPV and an all-IPV schedule were considered acceptable alternatives. In 1999, two doses of IPV were recommended to start the primary series, followed by two doses of either poliovirus vaccine. As of January 2000, an all-IPV schedule is currently being implemented in the United States for routine childhood vaccination. Several unusual features are associated with the major public health policy change from an all-OPV to a sequential schedule, including (1) the process of involving a neutral party (i.e., the IOM); (2) the perceived concerns expressed before the change in policy with regard to provider and parent compliance, which could affect the hard-earned gains in raising immunization coverage rates; (3) the ethical issues surrounding the change (e.g., societal versus individual protection) and the influence that a single case of VAPP may have on national policy; (4) the relative lack of importance of cost-effectiveness data; and (5) the weight of progress in the global polio eradication initiative spurring the change in the United States and, increasingly, in other industrialized countries. The IOM assisted in the evaluation of the national poliomyelitis vaccination policy in 1977 and again in 1988. The 1988 review recommended that a sequential IPV-OPV schedule be considered at such time that a combination vaccine becomes available. Also, the IOM raised several important questions. Extensive research to address the questions raised by the IOM had been conducted so that, in 1996, more data were available for the decision-making process. The primary reasons for the change in vaccination policy were (1) the continued occurrence of VAPP in the absence of indigenously acquired wildtype poliovirus-associated paralytic disease, (2) the reduced risk for importation and spread of wild-type poliovirus caused by the progress of the global polio eradication initiative, (3) evidence from vaccine trials that combined IPV-OPV schedules are safe and immunogenic, and (4) maintenance of high levels of population immunity to poliovirus. The global effect of a national change in poliomyelitis vaccination policy was also considered in this policy-making process. Some members of the public health and medical communities raised objections that an increased reliance on IPV in the United States could lead other countries, especially developing countries, to inappropriately abandon OPV and increase reliance on IPV for routine vaccination. Experience from the global smallpox eradication campaign indicated that this scenario was unlikely. The United States ceased vaccinating against smallpox in 1971, 6 years before smallpox was eliminated from the world, without jeopardizing the global smallpox campaign. Subsequently, the effect on the global eradication initiative has been negligible. This article illustrates the potential discrepancy between expressed theoretic concerns about the number of injections and the actual practice once vaccination policy recommendations become the standard of care and that appropriate training and education can overcome these initial concerns. The authors found that compliance with the recommended use of IPV for the first and second doses as part of the sequential schedule was high, independent of socioeconomic status and ethnicity. The need for additional injections did not present a barrier to completion of the recommended childhood immunization schedule. (ABSTRACT TRUNCATED)

Impact of the Sequential Poliovirus Immunization Schedule: A Demonstration Project

OBJECTIVE Researchers for this project evaluated compliance with the sequential poliovirus immunization schedule that uses inactivated poliovirus vaccine (IPV) for the first 2 doses of the polio immunization series, and assessed immunization coverage rates before and after implementation of this schedule at 6 public health clinics serving 1 county in Georgia. DESIGN Immunization histories for 3 birth cohorts of infants were compared: (1) the baseline cohort, born January 1 through June 30, 1995; (2) the evaluation cohort, born January 1 through June 30, 1997, after implementation of the schedule change; and (3) the dose-3 cohort, born August 1 through November 30, 1996 (i.e., old enough to be eligible for a third dose of poliovirus vaccine following implementation of the sequential schedule). RESULTS Following implementation of the new poliovirus immunization recommendations, 94% (534 of 567) of infants who received their first dose of poliovirus vaccine by age 3 months received IPV. Among these infants, 99.6% (532 of 534) were also up to date (UTD) for first doses of diphtheria and tetanus toxoids and acellular pertussis vaccine (DTP1/DTaP1), 99.6% (532 of 534) were UTD for first doses of hemophilus influenza type b (Hib 1), and 98.6% (527 of 534) had received at least one dose of Hepatitis B. Among infants visiting the clinics for their first or second dose of poliovirus vaccine, DTaP/DTP, and/or Hib, 76% received 3 or 4 simultaneous injections. In the dose-3 cohort, 78% (145 of 185) of infants who received a third dose of poliovirus vaccine had received 2 doses of IPV and 1 dose of oral poliovirus vaccine. CONCLUSIONS Compliance with the recommended use of IPV for the first 2 poliovirus immunization doses as part of the sequential schedule was very high in this low-income and ethnically diverse population. Furthermore, the need for additional injections did not impede the delivery of recommended childhood immunizations.