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Combined testing for antibodies to rubella non-structural and envelope proteins sentinels infections in two outbreaks
M A Chernesky1, F Smaill, J B Mahony
1McMaster University Regional Virology Laboratory, St. Joseph's Hospital, Hamilton, Ontario, Canada.
Abstract:
Two separate outbreaks of Rubella occurred in Hamilton, Ontario, Canada, 7 yrs apart, with a peak incidence for both in the month of April. A total of 138 cases, 51 in 1978 and 87 in 1985, was observed, the majority being in adolescents and young adults 15-25 years of age. Cases were diagnosed by the presence of Rubella IgM antibody or the combination of a negative passive hemagglutination (Rubacell-Abbott) and a positive enzyme immunoassay (EIA) or hemagglutination inhibition (HI) test on a single serum or by seroconversion for Rubella IgG antibody. Routine screening of sera with the Rubacell test, which measures antibodies to nonstructural rubella proteins together with HI or EIA testing of the negatives, served as a sentinel for rubella infection in the community during both outbreaks. Rubacell antibodies usually appeared 2-3 wk after onset of infections, and when present contained either or both IgG and IgM. Only 8/103 cases had a history of Rubella vaccination. Two of three products of conception yielded rubella virus in cell culture.
Insights
Two Rubella outbreaks in Hamilton, Canada, primarily affected adolescents and young adults. Diagnostic methods included Rubella IgM antibody tests and seroconversion, with few cases reporting vaccination history.
Area of Science:
- Epidemiology
- Virology
- Immunology
Background:
- Rubella (German measles) is a contagious viral infection.
- Outbreaks can disproportionately affect unvaccinated or under-vaccinated populations.
Purpose of the Study:
- To describe the epidemiology and diagnostic approaches of two Rubella outbreaks in Hamilton, Ontario.
- To evaluate the effectiveness of serological testing as a sentinel for community surveillance.
Main Methods:
- Retrospective analysis of 138 Rubella cases from 1978 and 1985 outbreaks.
- Diagnostic criteria included Rubella IgM antibody detection, combined serological testing (passive hemagglutination, EIA, HI), and IgG seroconversion.
- Rubella virus isolation from products of conception.
Main Results:
- Two distinct Rubella outbreaks occurred 7 years apart, peaking in April.
- A total of 138 cases were reported, predominantly in adolescents and young adults (15-25 years).
- Only 8 out of 103 cases had a documented history of Rubella vaccination; Rubella virus was isolated from two products of conception.
Conclusions:
- Rubella outbreaks continue to pose a risk, particularly to adolescents and young adults.
- Combined serological testing, including Rubella IgM and nonstructural protein antibodies, is effective for diagnosis and surveillance.
- Low vaccination rates contributed to the observed outbreaks.