Performance of rubella suspect case definition: implications for surveillance

Abstract

OBJECTIVE:To assess the performance of the rubella suspect case definition among patients with rash diseases seen at primary care units. METHODS:From January 1994 to December 2002, patients with acute rash, with or without fever, were seen at two large primary health care units and at a public general hospital in the municipality of Niterói, metropolitan area of Rio de Janeiro, Brazil. Data from clinical and serologic assessment were used to estimate the positive predictive values of the definition of rubella suspect case from the Brazilian Ministry of Health and other combination of signs/symptoms taking serologic status as the reference. Serum samples were tested for anti-rubella virus IgM using commercially available enzyme immunoassays. Positive predictive values and respective 95% confidence intervals were calculated. RESULTS:A total of 1,186 patients with an illness characterized by variable combinations of rash with fever, arthropathy and lymphadenopathy were studied. Patients with rash, regardless of other signs and symptoms, had 8.8% likelihood of being IgM-positive for rubella. The Brazilian suspect case definition (fever and lymphadenopathy in addition to rash) had low predictive value (13.5%). This case definition would correctly identify 42.3% of the IgM-positive cases, and misclassify 26.1% of the IgM-negative cases. CONCLUSIONS:These results support the recommendation to investigate and collect clinical specimens for laboratory diagnosis of all cases of rash, for surveillance purposes. Although this strategy may increase costs, the benefits of interrupting the circulation of rubella virus and preventing the occurrence of congenital rubella syndrome should pay off. KEYWORDS

Oral Fluid Testing during 10 Years of Rubella Elimination, England and Wales

“…Despite some missing clinical information and the absence of information about arthralgia, this finding suggests that the WHO clinical case definition is not sufficiently accurate for surveillance in the postvaccine era. This finding also emphasizes the need to have laboratory confirmation of all clinically diagnosed cases to accurately monitor rubella elimination ( 27 ). …”

A rare case of congenital rubella syndrome

“…From 18 to 24 weeks, the risk of infection is about 25%, with hardly any risk of congenital defects [5]. Though the exact teratogenic mechanism of in utero rubella infection remains unidentifi ed, viral replication in the cells during fetal organogenesis seems to be accountable for CRS [6].…”

Congenital Rubella Syndrome—Case Report

“…Cataracts and microphthalmia occur 60-70%; congenital glaucoma and intracranial calcifications are rare, more so in the neonate [4][5][6][7]. Though the exact teratogenic mechanism of in utero rubella infection remains unidentified, viral replication in the cells during fetal organogenesis seems to be accountable for CRS [8].…”