Later On

A blog written for those whose interests more or less match mine.

And, speaking of bad healthcare, a Spanish anesthetist infected hundreds with hepatitis C

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Interesting how they proved him to be the culprit, as reported in The Scientist by Chris Palmer:

Something was amiss in the Spanish coastal city of Valencia. A dozen cases of hepatitis C, a potentially fatal blood-borne viral infection that causes cirrhosis of the liver, had turned up within a short time span in early 1998. As more cases popped up over the ensuing weeks, one fact linked virtually all the cases: the patients had at one time or another been admitted to one of two local hospitals.

Valencian public health department officials set up a committee of local scientists and epidemiologists to get a handle on the outbreak. One tool the health department planned to use to identify the source of the infections was a genetic analysis that was just starting to be employed in court cases related to HIV transmission. The forensic tool, based on the principles of molecular phylogenetics, could help infer the most recent common ancestor of virus strains from any two people based on the estimated rate of accumulated viral mutations.

Because of his experience in molecular biology, Fernando González-Candelas, an evolutionary geneticist at the University of Valencia, was tapped to head the health department’s phylogenetic testing. As the investigation expanded, the number of possible cases of infection soared into the hundreds. “We had no idea when we were contacted that it was going to be such a big and complicated problem that it turned out to be,” says González-Candelas. Ultimately, 275 people—almost all of them patients at one or both of two hospitals in Valencia—were determined to be victims of the outbreak, which stretched back to 1988.

When the Valencian provincial court learned of the health department’s scientific committee, it asked to use the findings of the phylogenetic analysis as evidence for a criminal case against Juan Maeso, an anesthetist who worked regularly at the two hospitals (and occasionally at others) and who had administered painkillers intravenously to all of the known hepatitis C patients following surgical procedures.

González-Candelas and his team spent the next 2 years comparing 4,000 sequences of the hepatitis C virus (HCV) genome from 322 patients who had contracted HCV during Maeso’s tenure to more than 100 genome sequences from 28 HCV haplotypes that Maeso carried.

But virus genomes evolve rapidly—about one million times faster than the human genome. “There is a race between the virus and the immune system, with one trying to control the other and the other trying to escape,” says González-Candelas.

This means that viral sequences from the source and even a recently infected individual are almost never identical, according to Anne-Mieke Vandamme, an epidemiological virologist at Katholieke Universiteit Leuven in Belgium who was not involved in the research. However, the rate at which mutations accumulate is relatively constant, so recently infected individuals should have viruses with higher sequence similarity to the source than those infected in the distant past. . .

Continue reading.

Written by Leisureguy

19 October 2013 at 10:49 am

Posted in Evolution, Law, Medical, Science

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