Lessons Learned from Establishing and Evaluating Indicators of the Quality of Measles Surveillance in the United States, 1996–1998

How adequate is measles surveillance in the United States? Investigations of measles-like illness, 2010-2017

Given the availability of an effective and safe vaccine, the World Health Organization (WHO) declared that global measles eradication is achievable, and measles elimination goals have since been established as interim steps toward eradication. As part of a strategy to maintain elimination, the Pan American Health Organization (PAHO) and WHO stipulate a minimum annual reporting rate of discarded non-measles cases of ≥2 per 100,000 population, in order to ensure sensitive surveillance and adequate investigative effort. With its effective vaccination program, the United States in 2000 was among the first countries to verify elimination, although subsequently, it has not routinely reported discarded rates. We estimated MLI investigation rates among insured individuals during 2010-2017, using data from the MarketScan® databases. We defined "MLI investigations" as measles serologic testing within 5 days following diagnostic codes for measles-compatible symptoms and conditions. We provide a rationale for pre-specifying three subgroups for analysis: children aged ≤15 years; males aged 16-22 years excluding data from summer months; and males aged ≥23 years. MLI investigation rates ranged from 6.6─26.4 per 100,000, remaining stable over time except during the 2015 measles outbreaks when rates increased, particularly among young children. In addition to high vaccine uptake, measles elimination requires ongoing vigilance by clinicians and high-quality, case-based surveillance. Estimated rates of MLI investigations in this U.S. population suggesting that the quality of measles surveillance is sufficiently sensitive to detect endemic measles circulation if it were to be occurring.

SERVAL: a new framework for the evaluation of animal health surveillance

Animal health surveillance programmes may change in response to altering requirements or perceived weaknesses but are seldom subjected to any formal evaluation to ensure that they provide valuable information in an efficient manner. The literature on the evaluation of animal health surveillance systems is sparse, and those that are published may be unstructured and therefore incomplete. To address this gap, we have developed SERVAL, a SuRveillance EVALuation framework, which is novel and aims to be generic and therefore suitable for the evaluation of any animal health surveillance system. The inclusion of socio-economic criteria ensures that economic evaluation is an integral part of this framework. SERVAL was developed with input from a technical workshop of international experts followed by a consultation process involving providers and users of surveillance and evaluation data. It has been applied to a range of case studies encompassing different surveillance and evaluation objectives. Here, we describe the development, structure and application of the SERVAL framework. We discuss users' experiences in applying SERVAL to evaluate animal health surveillance systems in Great Britain.

Evaluation of animal and public health surveillance systems: a systematic review

Disease surveillance programmes ought to be evaluated regularly to ensure they provide valuable information in an efficient manner. Evaluation of human and animal health surveillance programmes around the world is currently not standardized and therefore inconsistent. The aim of this systematic review was to review surveillance system attributes and the methods used for their assessment, together with the strengths and weaknesses of existing frameworks for evaluating surveillance in animal health, public health and allied disciplines. Information from 99 articles describing the evaluation of 101 surveillance systems was examined. A wide range of approaches for assessing 23 different system attributes was identified although most evaluations addressed only one or two attributes and comprehensive evaluations were uncommon. Surveillance objectives were often not stated in the articles reviewed and so the reasons for choosing certain attributes for assessment were not always apparent. This has the potential to introduce misleading results in surveillance evaluation. Due to the wide range of system attributes that may be assessed, methods should be explored which collapse these down into a small number of grouped characteristics by focusing on the relationships between attributes and their links to the objectives of the surveillance system and the evaluation. A generic and comprehensive evaluation framework could then be developed consisting of a limited number of common attributes together with several sets of secondary attributes which could be selected depending on the disease or range of diseases under surveillance and the purpose of the surveillance. Economic evaluation should be an integral part of the surveillance evaluation process. This would provide a significant benefit to decision-makers who often need to make choices based on limited or diminishing resources.

Enhanced surveillance for measles in low-incidence territories of the Russian Federation: defining a rate for suspected case investigation

The rate of case investigation for measles-like illness (MLI) is an important indicator for the quality of measles surveillance in countries targeting measles elimination. However, a benchmark rate is still being discussed. We assessed different rates of investigation in 11 territories of the Russian Federation with low reported measles incidence during the previous 4-7 years. Each territory maintained their existing surveillance activities and also undertook additional surveillance activities for MLI over a 3-year period. The annual routine rate of investigation varied from 0·06 to 1·8/100,000 population; the overall rate of investigation, including enhanced surveillance, varied from 1·4 to 7·2/100,000. Forty-nine (30·8%) of 159 measles cases detected were identified through enhanced surveillance. Based on the results of this study, the Russian Federation concluded that a rate of routine investigation of 2/100,000 provided the best balance between available resources and sensitivity for detection of measles cases.

Adequacy of surveillance to detect endemic rubella transmission in the United States

BACKGROUND

Reported rubella cases in the United States are at the lowest numbers since the introduction of vaccine, suggesting that endemic transmission may have been interrupted. It is necessary to validate that the observed absence of rubella is due to the disappearance of disease rather than a failure of rubella surveillance.

METHODS

Adequate rubella surveillance to detect ongoing transmission is characterized by evidence that rubella investigations are being conducted, detection of importations, and lack of spread from confirmed cases. We reviewed rubella surveillance data and activities from 5 sources: (1) data reported to the national surveillance system; (2) a survey of health departments and public health laboratories, including questions regarding any links between measles and rubella surveillance; (3) enhanced rubella surveillance activities in California and in New York City; (4) sentinel surveillance along the US-Mexico border; and (5) case detection in 8 large health maintenance organizations (HMOs).

RESULTS

During 2002-2004, 35 cases of rubella were reported to the national system, including 12 (34%) imported cases. The 39 programs that responded to our survey reported conducting 1482 investigations for rubella; according to another national survey, 1921 investigations were conducted for measles. Forty-one laboratories responded to our survey and reported conducting 6428 tests for acute rubella. No previously undetected (or unreported) cases of rubella or congenital rubella syndrome were identified by our survey or reviews of surveillance in California, New York, and along the US-Mexico border, and no additional cases were detected in the HMO database.

CONCLUSIONS

No previously unrecognized spread cases or outbreaks of rubella were detected. Surveillance in the United States is sufficiently sensitive to identify indigenous cases of rubella, if they were occurring, supporting the contention that rubella has been eliminated from the United States.

Completeness of Measles Case Reporting: Review of Estimates for the United States

Measles surveillance is complex: the patient must seek health care, the diagnosis must be recognized by the physician, and the case must be reported to health departments. The portion of total (incident) measles cases that is reported to health departments is termed "completeness of reporting." Few studies describe this measure of the quality of surveillance in the United States; these studies use different methods, but they are all limited because the actual number of measles cases needed to derive completeness of reporting could not be determined. Estimates of completeness of reporting from the 1980s and 1990s vary widely, from 3% to 58%. One study suggests that 85% of patients with measles sought health care, the proportion of compatible illnesses for which measles was considered varied from 13% to 75%, and the proportion of suspected cases that were reported varied from 22% to 67%. Few cases were laboratory-confirmed, but all were reported. Surveillance in the United States is responsive, and its sensitivity likely increases when measles is circulating. Continued efforts to reinforce the clinical recognition and reporting of measles cases are warranted.

Syndromic Surveillance for Measleslike Illnesses in a Managed Care Setting

Surveillance for measles must be enhanced to support the objective of measles elimination in the United States. Many conditions produce febrile rash illnesses that are clinically similar to measles; investigations of measleslike illnesses (MLIs) should occur regardless of the incidence of measles. Few data exist regarding the incidence of MLI in the United States, and it is unknown how providers evaluate patients with such conditions. We searched databases at a large managed care organization to obtain complete ascertainment of MLI during 1994-1998. Among 6000000 patient encounters, 68 records were identified that met the study case definition. The incidence of MLI was 4.5 cases/100000 persons/year. Measles diagnoses were considered by physicians for 9 patients (13.2%); 2 were laboratory-tested and reported to the state health department and the other 7 were given alternative diagnoses. It was not possible to determine for the remaining MLI patients whether measles was ruled out on clinical grounds or whether the possibility was not considered. Provider education regarding evaluation and reporting of measles is warranted. Databases at health care plans can be used to address public health issues and to establish syndromic surveillance for communicable diseases.