Rubella

Okay, now to switch over to rubella. This is something that we really shouldn’t need to talk about today. Rubella should be gone, and yet there are a number of young adults who weren’t vaccinated and who have been protected by herd immunity and who are susceptible, particularly adults who travel who are serologically susceptible can still get rubella. The last major outbreak in California was nine years ago, but it is still a risk, a small risk. The risk period with rubella and the timing of maternal infection is greatest in the first eight weeks of pregnancy, in fact even if infection occurs a few weeks before onset of pregnancy. Here we have 16% from 13-20 weeks, but these abnormalities in general are not so clear cut, and the main risk really is in the first 12 weeks, or at most, 16 weeks. The risk after 20 weeks is zero. The main manifestations by percent occurrence is in utero death, in utero growth retardation and deafness are the most common manifestations. Cataracts in roughly one-third, retinopathy which is not particularly debilitating in about one-third, retardation in 10-20%, and frequently this is over-diagnosed because deafness and lack of development because of deafness is confused. Acute meningoencephalitis, other manifestations that you see here associated with acute infection. This is a baby, a very classic baby which used to be called “blueberry muffin” syndrome with extensive involvement and the outcome for these babies with disseminated disease and hepatosplenomegaly and frequently pneumonia was poor. This is a baby with congenital glaucoma. This baby actually has a cataract but also has microphthalmia. Radiolucency that you see here is a manifestation of rubella and of course also of congenital syphilis.

The diagnosis of congenital rubella; the best method actually is culture, but you need to alert the lab as to what you are looking for because you need special testing in the laboratory to isolate rubella. Rubella is an easy virus to isolate and it should be done on newborns, because there are a lot of pitfalls in serology. A lot of false positives and false negatives. IgM-specific rubella antibody has less false positives than CMV, but about 10-20% of babies with congenital rubella have immune deficiency as a manifestation of their disease, so they may have negative antibody studies and yet have florid infection. Then lastly, persistence of IgG antibodies in a child who looks otherwise well; the transplacental antibodies should fall two-fold every month. So if the titer is not dropping then you have evidence of a congenital infection.

Now we will go to hepatitis B. The major transmission risk factors for infection in the infant are listed here. First of all, presence of E antigen. The mother is surface antigen positive and also E antigen positive. In those circumstances there is an 80-95% transmission rate to the fetus. Asians have a higher attack rate than non-Asians. Acute hepatitis B in the third trimester has a higher rate. Then the transmission can be directly correlated with the number of surface antigen particles in the mother’s blood. There are five possible manifestations with congenital or neonatally acquired hepatitis B from the mother. The first is; asymptomatic transient antigenemia followed by recovery and antibody. This is the minority; only about 10%. Asymptomatic but persistent antigenemia, and this is unfortunately all too common. Hepatitis with clearing of antigen, and this is actually quite rare. And hepatitis which becomes chronic persistent or chronic active. These two really shouldn’t be separated because persistent antigenemia leads to bad outcome eventually. Then fulminant hepatitis with death. All of you know this, and we’ve been very successful, all pregnant women should be screened for active hepatitis B surface antigen and exposed in any situation where the mother is positive, in fact any situation where she is likely to be positive, the baby should be treated with HBIG within 12 hours of birth and then receive vaccine at birth, then one month and six months later. The recent sort of phobia relating to thimerosal, some people might overlook this and this is the first priority. If there is any likelihood of hepatitis B there shouldn’t be any concern about thimerosal in the vaccine and the baby should be vaccinated.

One Response to Rubella

  1. […] to 1:10,000 births. The manifestations; the list looks sort of like that that I showed you for rubella. The findings that you see here. The outcomes are retardation in 85% of diagnosed cases, […]

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