• Rationale for Surveillance
• Recommended Case Definitions
• Recommended Surveillance Measures
• Recommended Minimum Data Elements
• Principal Use of Data for Decision-Making
• Main Surveillance Indicators

Rationale for Surveillance

Rubella virus continues to circulate freely in most countries of the region. After a complete investigation, many suspected measles cases are ultimately found to be rubella. Moreover, cases of the Congenital Rubella Syndrome (CRS) have been found in all countries of the Region that have established CRS surveillance systems. This suggests that CRS is a major public health problem in all countries of the Americas

Rubella surveillance should be integrated with measles surveillance. The purpose of rubella surveillance is to detect circulation of rubella virus, not to detect every case of rubella. A separate rubella surveillance system is not needed. All sera from suspected rubella cases which test negative for rubella IgM antibodies should be tested for measles IgM antibodies and vice versa.

Recommended case definitions

Rubella control/elimination programs should use the following standardized case definitions, revised from PAHO's Measles Eradication Field Guide, 1999, and the WHO Recommended Surveillance Standards from the 2nd. Ed., June 1999, revised by the PAHO's Communicable Diseases Program.

• Suspected rubella case: any patient in whom a health care provider suspects the possibility of rubella.
  
  In suspected a rubella case, a serum sample should be collected from the patient upon initial contact with the health provider. This sample must be collected within 30 days of rash onset to be considered adequate.
• Laboratory-confirmed case: a suspected rubella case that after complete investigation is:
1. Confirmed as rubella using commercially available enzyme immunoassays (EIA) for measles or for rubella IgM antibodies, and/or
2. Confirmed by isolation rubella virus and/or
3. Epidemiologically linked to another laboratory-confirmed case (the epidemiological link is established if any contact between the suspected case and the laboratory-confirmed case has occurred anytime during the month prior to rash onset).
• Clinically-confirmed case: a suspected rubella case that is not completely investigated for any reason. This could include: patients that died before the investigation was complete, patients lost to follow-up, or patients without adequate specimens submitted for laboratory analysis.
• Discarded: a suspected rubella case that has been completely investigated, including an adequate blood specimen, which lacks serologic evidence of infection, has no virus isolated, and does not have epidemiological link to a laboratory-confirmed case. If laboratory results indicate another viral infection compatible with the clinical symptoms, such as dengue, the case should be discarded as well.

Recommended Surveillance Measures

• Blood samples from all rubella suspected cases that are IgM negative for rubella should be tested for measles within 24 hours.
• In the case of laboratory-confirmed rubella (or dengue) outbreaks, the total number of samples that are negative for either rubella (or dengue) might be overwhelming. In such a case, the surveillance team, in conjunction with the laboratory, should decide which samples to test for measles.

• The reporting system must cover health facilities, private practitioners, hospitals and laboratories and have at least one reporting source for every geopolitical unit;
• Written material should be provided to all health personnel describing their responsibilities and how to report cases, collect samples and send them for laboratory confirmation;
• Investigation of all suspected cases should take place within 48 hours of rash onset. It should include:
• Filling the case report form,
• Investigation of contacts of the suspected case to determine if other cases have occurred,
• Taking blood samples and samples for viral isolation (usually urine) from all sporadic cases and from 5-10 cases from each outbreak.
• Weekly reporting of data, even in the absence of cases, is critical;
• Timely feedback to all participants of the surveillance system, keeping them informed of where and when cases are occurring, is essential;
• The reporting system must be monitored monthly using the surveillance indicators;
• Cooperation from the private medical community by reporting suspected cases to the system is essential for all surveillance efforts.

Recommended Minimum Data Elements

Case-based data (to be linked using the unique identifier to specimen-based data for analysis): (I) unique identifier; (II) geographical area (district and province); (III) name; date of birth (IV); (V) date of rash onset; (VI) date of notification; (VII) date of case investigation; (VIII) date of specimen collection; (IX) date when specimens were sent to the laboratory; (X) number of doses of measles-containing vaccine received; (XI) date of last doses of measles-containing vaccine; (XII) if source of infection was identified; (XIII) results of serology; (XIV) results of viral isolation; (XV) final classification; (XVI) name of investigator.

Specimen-based data (to be linked to case-based data for analysis): (I) unique identifier (MESS number when available); (II) specimen number; (III) date of rash onset; (IV) date of blood (or urine, nasopharyngeal secretion) specimen collection; (V) date specimen sent to laboratory; (VI) date specimen received in laboratory (VII) results of serology; (VIII) results of viral isolation.

Principal Uses of Data for Decision Making

• Track rubella virus circulation (in an eradication process, one case must be considered as an outbreak);
• Detect and investigate outbreaks to ensure proper case management and determine reasons for its occurrence;
• Monitor routine coverage for immunizations in all municipalities and focus efforts in high-risk municipalities (those where vaccination coverage is lower than 95%) for planning mopping up and other immunization activities;
• Identify when next follow-up campaign is due;
• Monitor performance of surveillance using standard indicators and strengthen surveillance in low performing areas.

Main Surveillance Indicators

• % of reporting sites that report each week;
• % of reported suspected cases investigated within 48 hours of rash onset;
• % of suspected cases with complete report form;
• % of suspected cases with blood specimen collected within 30 days of rash onset (nonetheless, when outbreaks occur, cases epidemiologically linked to laboratory-confirmed case are confirmed without needing blood specimens);
• % of blood specimens for which results were received within 7 days of receipt of the sample by the laboratory.