CSI: Virology

The best mysteries are ones where the reader, if they are following along carefully, can figure out the answer to the problem as the lead characters do.

If you read science blogs and love evolution, then you know exactly where this is headed:

Molecular evolution in court: analysis of a large hepatitis C virus outbreak from an evolving source.

Lets say you are an epidemiologist, and youve noticed something peculiar-- numerous individuals have turned up with Hepatitis C infections. Well, people get HepC all the time, thats not noteworthy. BUT... there were a *lot* of people getting sick. Not just a few-- almost 200. That is an outbreak. And all of these individuals would be classified as 'low risk' to acquiring HepC... but they all had one thing in common.

They all got sick after minor surgeries at the same clinic.

!!!

What does this mean???

Well, we are nerds, so a great way to attack this mystery with that one starting point is nerdery: Statistics. Take all the patients at this clinic for the past few years-- 66,000 people. Was there any association between, say, the procedure done, the equipment used, the rooms used, etc, and HepC diagnosis?

The epidemiologists examined the association of over 66,000 people who had undergone surgery in the two hospitals with the usual risk factors for infection in surgical procedures: surgeon, surgery room, type of surgery, anesthesiologist, type of anesthesia, etc. The only significant factor (adjustedOR = 28.5, 95% CI = 9.83-82.59) was this anesthetist (Vanaclocha and Martínez, pers. comm.) Furthermore, of the initial 197 cases considered to be included in the outbreak, 184 had been anesthetized by him.

BAM!  A suspect identified with MATH!

But could you convict someone with math alone? Was there some way to get hard, real evidence that this anesthetist, somehow, infected a *LOT* of people with HepC?

Heck yeah there is-- More nerdery: Evolution

Viruses change over time. We know the usual rates at which individual viruses, like HepC mutate. Weve also got computer programs (more math!) written to compare lots and lots of DNA sequences to one another and generate a visual representation of how similar those sequences are. aka, phylogenetic trees.

If sequences are closely related (as in they were all infected by the same parent viruses), they will cluster with one another in a phylogenetic tree. If they were infected from another source, they will show up as a distant branch. The same idea has been used to convict people of intentionally infecting others with HIV here in the US.

We also have computer programs (MOAR MATH!!!) written to compare sequences to a potential parent sequence, to estimate how long a person was infected. The same kind of programs were used to prove the Tripoli 6 could not have infected those children in Libya with HIV.

So what did evolution tell us about this HepC outbreak? How did the patients HepC sequences compare to that of the suspect?

The analysis was used to discriminate who of the potential victims had been actually infected by the common source, to provide an individual assessment of the likelihood of this assignment, and to obtain an estimate of the date of infection for each patient. These results helped the court to convict the anesthetist of professional malpractice leading to the infection of 275 of his patients.

Turns out the source of the outbreak was the anesthetist. Turns out the statistics werent lying ;) He was stealing pain meds from patients by injecting himself with the drugs first, then injecting the rest into the patient, exposing the patients to his HepC infected blood.

Mystery solved with forensic virology, evolution, and math.

Im sure Creationist lawyers like, oh, Ill throw him a bone and mention his name-- Casey Luskin-- will be on a plane to Spain tomorrow to free this poor innocent man. What with evolution being a lie and such, the more likely explanation is that the Christian god specially created the HepC virus in each one of those patients individually. The only reason they look alike is because the same God made them all.

... That will go over well in court... right?