Rubella reinfection

Current epidemiology of rubella and congenital rubella syndrome in Australia: progress towards elimination

This study evaluates the evidence for elimination of rubella and congenital rubella syndrome (CRS) in Australia, drawing on three national serosurveys conducted between 1996 and 2007 and supported by statutory notification and vaccine coverage data. Anti-rubella IgG seropositivity was defined as ≥ 10 IU/ml by EIA. Between 1998 and 2007, rubella notifications fell >100-fold, to an average of 2 cases per million and there were five confirmed cases of CRS, two of which were locally acquired in 2003. Weighted overall seropositivity remained constant among 1-49 year-olds (89.6% in 1999; 88.1% in 2007). Between 2002 and 2009, 95% of children received at least one dose of the measles-mumps-rubella (MMR) vaccine. All three serosurveys provided estimates for R less than 0.5, well below the epidemic threshold of 1. All available data are supportive of Australia being considered for elimination status. Further reductions in incidence of CRS will require continued attention to vaccine coverage in overseas-born women, as well as the maintenance of current high coverage level of two-dose MMR vaccination.

Rubella reinfection; role of neutralising antibodies and cell-mediated immunity

BACKGROUND

Rubella virus may be transmitted to the fetus following rubella reinfection in early pregnancy. The mechanisms responsible for maternal-fetal transmission in women with pre-existing rubella antibodies are, however, unclear.

OBJECTIVES

To evaluate the protective role of rubella specific neutralising antibodies and cell-mediated immunity in rubella reinfection.

STUDY DESIGN

Rubella Nt antibodies were measured in sera obtained from: women who experienced rubella reinfection during pregnancy, volunteers experimentally challenged with rubella vaccine and women attending for routine rubella antibody screening. Cell-mediated immunity was assessed by measuring rubella specific LT responses among women who had experienced rubella reinfection during pregnancy.

RESULTS

Some women experienced rubella reinfection during pregnancy despite the presence of Nt antibodies in sera obtained before contact. Only 2 of 13 (15.3%) volunteers with low levels (< 15 IU/ml) of rubella antibody had detectable Nt antibodies prior to experimental challenge. Despite this, they did not develop rubella viraemia following challenge and virus excretion was detected in only one case, although the majority (11/13, 84.6%) demonstrated a significant rise in antibody titre. Among pregnant women screened as having a low level of rubella antibody antenally, only 37% had detectable Nt antibodies. Among 23 women who experienced rubella reinfection during pregnancy 4 months to 6 years (mean 32 months) previously, 20 (86.9%) had a positive rubella-specific LT response. Only one of 4 cases where rubella virus was transmitted to the fetus failed to produce a a specific LT response.

CONCLUSIONS

This study indicates that rubella reinfection is not associated with a lack of Nt antibodies or persistent impairment of rubella-specific LT responses.

Molecular biology of rubella virus

This chapter summarizes the present medical significance of rubella virus. Rubella virus infection is systemic in nature and the accompanying symptoms are generally benign, the most pronounced being a mild rash of short duration. The most common complication of rubella virus infection is transient joint involvement such as polyarthralgia and arthritis. The primary health impact of rubella virus is that it is a teratogenic agent. The vaccination strategy is aimed at elimination of rubella and includes both universal vaccination of infants at 15 months of age with the trivalent measles, mumps, rubella (MMR) vaccine and specific targeting with the rubella vaccine of seronegative women planning pregnancy and seronegative adults who could come in contact with women of childbearing age, although it is recommended that any individual over the age of 12 months without evidence of natural infection or vaccination be vaccinated. Medically, the current challenge posed by rubella virus is to achieve complete vaccination coverage to prevent resurgences.

Childhood exanthems. Old and new

Exanthems are a common cause of rashes in children. Several recent developments have sparked a renewed interest in this group of diseases, including the identification of parvovirus B19 and human herpesvirus 6 as the causative agents of erythema infectiosum and roseola infantum. The resurgence of measles as a childhood exanthem has caused a re-examination of current immunization practices. The most common and clinically significant exanthems are discussed, with an emphasis on new findings, origins, clinical manifestations, differential diagnosis, and management.

Rubella in the United Kingdom

The first description of rubella in the UK was by an English physician, Dr William Maton, who reported an outbreak of an illness resembling a mild form of scarlatina in a boys' public school in 1815 [1]. Some years later, when observing the spread of a rash-associated illness in a large family, Maton described the characteristic clinical features of rubella, namely a mild prodromal illness followed by a generalized and often tingling rash lasting for a few days and associated with enlarged and tender glands in the occipital and postauricular regions. He also correctly identified the relatively long incubation period of rubella and noted the absence of fever and other signs of constitutional upset. Maton did not suggest an English name for this disease which had been previously described and called Rothëln by German physicians in the late 18th century. The term ‘rubella’ (Latin for ‘little red’) was first used in 1866 by another English physician, Dr Henry Veale, when describing an outbreak of Rothëln in a boys' school in India [2].