Category Archives: Viruses

I don’t want my child to get shingles!

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A couple days ago I saw a post on Facebook  expressing anger over how the chicken pox vaccine had caused a rise in shingles, and the request for anyone who’s child had chicken pox to let the poster know so she could bring her child over to get infected.  Does this make sense?  Let’s unpack it.

What is shingles?

Shingles or Herpes  Zoster is a painful rash caused by the same virus that causes chicken pox.  The varicella-zoster virus (VZV) is a herpes virus.  One of the characteristics of herpes viruses is that after the initial infection the virus lies latent in the body.  Sometimes it reactivates.  The reactivation of VZV can cause shingles.  In order to get shingles you have to be infected with VZV.

Is there an increase in shingles due to the chicken pox vaccine?

Maybe.  Studies on this are inconclusive.  The vaccine was introduced in 1995.  It may be too soon to tell.  However, an increase in shingles after the introduction of the varicella vaccine had been predicted.  This was hypothesized based on the idea that an effective vaccine program would eliminate much of the wild-type VZV circulating.  It is thought that the “boost” people who had previously had chicken pox received from contact with the circulating virus kept their immune systems primed for a reactivation event. If the latent virus were to reactivate in their body, their immune system would be able to fight it off before any symptoms of shingles manifested.  Based on this hypothesis a shingles vaccine was developed to be given to people over 60, who are at the most risk for shingles.

Can you get shingles from the chicken pox vaccine?

Yes, you can.  The varicella vaccine is a live attenuated virus, which means that it is a virus that has altered to make it less virulent.  It does remain in your body as the wild-type virus does, and it can reactivate and cause shingles.  Current research shows that it reactivates less often than the wild type virus does and causes a milder shingles outbreak, with less chance of complications.  Of course this research only covers the two decades since the vaccine was introduced.  It is currently impossible to know about effects in future.

In light of all of this, does purposefully infecting your child with chicken pox make sense?

Not if what you are trying to avoid in shingles.  Current research shows that you are more likely to develop shingles, and the case is likely to be more severe,  after naturally catching chicken pox than you are from the vaccine.  The only way to make sure you don’t get shingles is to make sure you never encounter the either the wild-type or the vaccine virus.

image from Microsoft Office Clip art

HIV cure?

If you AIDShave Facebook friends that are anything like mine, the other day your newsfeed was full of excitement about this baby in Mississippi being cured of HIV. If this is true, it’s pretty exciting, but we need to keep that excitement in perspective.  Let’s examine what this really means.

Is this really true?

Maybe.   The research has been presented at a scientific meeting.  It has not yet been published in a scientific journal.  This is what we know.  A baby was born to an HIV positive mother, who was not given the usual anti-retroviral treatment that is recommended for HIV-positive pregnant woman to prevent transmission of the virus to the baby.    Two days after birth the babies blood was tested twice and a viral load was found.  Thirty-one hours after birth the baby was put on an anti-HIV drug cocktail.  This is uncommonly early start for such a cocktail.  Blood tests were performed three more time in the following weeks, detecting a viral load.  At 29 days the viral load was undetectable, this is a normal outcome of anti-retroviral therapy.  At 18 months treatment was stopped by the caretaker.  The child was not seen for six months.  When the child was brought back to the doctor, they expected to find that the virus had begun replicating again.  They did not find that.  They did find genetic evidence of the virus, but not that it was replicating.

So what really happened?

They don’t really know.  This is an anomaly.  They did not see the child for six months.  It’s not entirely clear what exactly caused the virus to be knocked out.  Erv, a blogger who knows a whole lot more than I do about HIV has a thought about this:

Babby already had Moms adaptive immune response working for her. And at birth, she was immediately put on antiretrovirals.
Limited genetic diversity in the transmission event + pre-existing anti-HIV antibodies + immediate drug therapy =  They might have gotten the drugs there before the quasispecies was established, thus there were no drug resistant variants present. Antiretrovirals and antibodies from Mom could do their work. Babbys developing immune system had an easier target to catch.

The researcher presenting this case has a slightly different theory:

Persaud, who plans to present her findings in full at a conference session tomorrow, suspects that the early treatment prevented the establishment of a reservoir of long-lived CD4 cells that harbor latent HIV infections; these CD4 cells avoid immune detection and are impervious to antiretroviral drugs because they are not actively producing new viruses. These reservoirs are a central reason why the virus persists even after decades of antiretroviral treatment.

How big a deal is this if it is true?

It’s a fairly big deal, but not earth shattering.  It suggests that if we start treatment so quickly after infection we may be able to catch the virus before it mutates into a drug resistant quasispecies or becomes established in a reservoir in the immune system.  It’s hard to imagine how this could be ethically confirmed by studies.  This was a single case of a pregnant woman who was not known to be HIV positive until she was in labor.  The standard of care is to treat HIV-positive pregnant woman with anti-retrovirals to prevent transmission to the child.  When this standard of care is followed transmission is very rare.  Withholding the treatment from the mother would be unethical.  Researchers would only be able to study this on the few children who do get infected.  Most of the children infected today are infected because the mothers did not receive adequate pre-natal care.  They would be unlikely to be in a position to receive this aggressive treatment after birth as well.

So we haven’t cured HIV then?

No we haven’t.  This might be a pretty exciting development in the already very effective field of anti-retroviral treatment.   HIV is no longer a death sentence.  It is a chronic disease that needs to be closely managed.  What this does suggest is that it may be possible to stop the virus before a full infection is established if treated soon enough after transmission – a kind of “morning after pill” for infection.  That’s pretty exciting, but not helpful to all the people who already have HIV.

image from openclipart.org