People shouting loudly and angrily against childhood vaccination seem to be either evil or ignorant of what the world was like before vaccines were readily available. And Hanlon’s razor tells us “Never attribute to malice what can be blamed on ignorance”. So, as my civic duty, I am starting a series on vaccine preventatble diseases. First up is rubella, or German measles.
German measles, so called as German physicians first characterised the disease, is caused by the Rubella virus (RUV). RUV infection can cause mild flu-like symptoms, a cough, joint-pain, and a distinct red rash (rubella is Latin for small red dots). However, 20-50% of people infected with RUV can be completely asymptomatic. RUV spreads through aerosols and patients are infectious during about a week before and after the rash. RUV infection is cleared after about 24 days with no long-term effects.
As far as I’ve described it, RUV seems like a, frankly, crap disease. Boring, self-limited, not really deadly to children or adults. But the reason why a vaccine against RUV was developed is due to the darker side to rubella: congenital rubella syndrome.
If a pregnant woman is infected with RUV, it can cross the placenta and infect the developing fetus. Once infected, the fetus cannnot clear it. RUV, through still unknown mechanisms, causes birth defects including: cataracts, heart defects, deafness, nerve damage resulting in mental retardation, and low birth weight. Even if they make it through birth, RUV-infected newborns are more susceptible to diabetes, thyroid dysfunction and brain damage.
This deadly nautre of rubella was first discovered in the 1940’s by Dr. Norman Gregg, who was the senior Ophthalmic Surgeon at the Royal Alexandra Hospital for Children in Sydney at the time. He thought that there were a lot more babies with cataracts than there should be. Looking deeper, he found that these babies also had heart defects and lower weight compared to normal. Looking at the babies’ eyes, he found that the lenses were fully developed, so it probably was not a developmental abnormality. He eventually found a link with the pregnant mothers’ being infected with RUV and the birth defects.
The peak in birth defects were a symptom of the peak in RUV being brought back to Sydney by soldiers returning from the war, after spending long months cooped up with others in fetid conditions. The scientific community slowly gathered pace by first accepting the RUV infection does in fact cause birth defects, development of a vaccine and implementing it in the community. While this was happening, Europe and the US experienced epidemics in 1963–1965. The children born with birth defects attributable to RUV infection during these epidemics numbered around 30 000, a third more than thalidomide had handicapped.
Since this many RUV infections were asymptomatic, but still able to be passed on, the only way mothers could protect their children was to stand by the door with a shotgun and blast at anyone trying to interact with them. This was not a good solution as the pile of rotting corpses would soon attract rats and spread other diseases. Even worse, the earlier you were infected during pregancy, the greater the effects of RUV on your fetus. Thus, the government implemented vaccination for girls only. However, that birth defects, though lower, still hung around. The reason behind this was that the men were still being infected and continually infecting the women. No vaccine is 100% effective and immunity can wane. Finally, universal vaccination was implemented.
This used the concept of herd immunity to stop RUV in its tracks. RUV can’t multiply without hosts and if the people that an infected patient comes in contact with are all immune, that particular infecting strain dies out. Note that a vaccine does not have to be 100% effective, just be effective enough to stifle secondary infections. The Australian vaccination program has proven to be successful, with absolutely no cases of rubella congenital syndrome being reported in 1998-2002 in babies born to Australian-born mothers.
This is a great outcome, but we can’t afford to relax yet. There are still people out there who did not get the vaccination and still act as reservoirs for RUV in the community. If we become complacent, we could see those smoldering infections spread and blaze through our community.
CDC (2001). Control and prevention of rubella: evaluation and management of suspected outbreaks, rubella in pregnant women, and surveillance for congenital rubella syndrome. MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports / Centers for Disease Control, 50 (RR-12), 1-23 PMID: 11475328
Webster WS (1998). Teratogen update: congenital rubella. Teratology, 58 (1), 13-23 PMID: 9699240