Course: BIS 105 Environmental Biology

Unit 3 Learning Module

Case Study - Murder with HIV
Copyright
Adapted from CK-12 Foundation, - Biology I Honors (CA DTI-3) by Douglas Wilkin .

Case Study - Murder with HIV

In January 1995 a nurse by the name of Janice Trahan discovered she was HIV positive after her gynecologist ran blood tests due to indications of a viral infection. Since she is a nurse she is at a higher risk of infection because of her contact with patients and needles. However, she was not aware of any incidents that may have resulted in her infection and did not believe that was how she became infected. She suspected her ex-boyfriend, Richard Schmidt, was the source of her infection even though he was not infected himself.

Richard Schmidt, a doctor, had an affair of ten years with Janice until July 1994 when she broke off the relationship. He does not personally have HIV, so why would Janice suspect him of being the source of her infection? She has a rare condition known as chronic fatigue syndrome. There is no cure for this condition, but one of the frequent treatments to reduce the symptoms is a vitamin B_12 injection that Richard had administered during their relationship. On August 4, Richard called Janice to say he was stopping by to give her another injection.

Janice believed this may have been how she was infected with HIV, but since Richard is not infected how could he infect her? She accused him of obtaining a contaminated blood sample from an HIV infected patient and then injecting her. HIV is not stable outside of the body for more than a few hours so this had to occur within a short time period. Investigators began looking through records of Richard's patients. They discovered a few irregularities. When they went looking for the laboratory log book, the one for the date in question was "missing." After further examination it was found to have been placed with log books from a decade earlier. In addition, a blood withdrawal on August 4th did not have an accession sticker associated with the withdrawal to track the samples being sent for testing, there was just a note it was for Dr. Schmidt. When prosecutors interviewed this patient, Donald McClelland, he testified that it wasn't a scheduled visit, he had been called into the office for a blood withdrawal. In addition, he was infected with HIV that had progressed to AIDS.

Investigators were definitely suspicious of Richard at this point, but most of the evidence was circumstantial. It was months after the injection in question occurred, so there was no chance of finding the contaminated needle. How can they prove beyond a reasonable doubt that he was the source of infection? To do this, they decided to do what is called a phylogenetic analysis. Samples of genetic information are sequenced to see how similar they are to one another. With a rapidly mutating virus like HIV, each person develops their own suite of unique viruses over time because of mistakes that are made when the virus is replicated. However, if the analysis is done soon after infection, there is little time for changes to have occurred and it provides a means of tracing the source of infection.

In the diagram below, called a cladogram, you can see how closely related a few different species are to one another. A node represents the common ancestor of the species to the right. The relatedness of two species is indicated by how far back (leftward) you need to go to reach a common ancestor. In the example below, a sheep and goat are more closely related to each other than either is to a cow.

We can make a similar diagram by comparing genetic sequences of HIV strains from different individuals to see how closely related different strains are. This is what researchers did to determine how similar the strains were from Janice and Donald. The results are shown below.

As you can see, the HIV sample that was most similar to Janice's strain was from the patient, Donald. Researchers also analyzed a second gene (Figure below) and came to similar conclusions.

As a result, in 1998 Richard Schmidt was convicted of second degree attempted murder and received a 50 year sentence without a chance for parole. Since he was 50 years old at the time of conviction, it is likely he will spend the rest of his life in jail. It was also revealed during the trial that Janice had also been infected with hepatitis C, another incurable disease. Again, the lab records were examined and a patient of Richard Schmidt was identified with hepatitis C that had been called into the office on August 2 under the premise that a blood sample was needed for research.

How Does This Relate to Evolution?

Why is this case notable for this unit? Because it was the first time the theory of evolution was used in a court case to convict someone of a crime. Remember the difference in meaning between theory in your everyday use and in science. Scientists are confident enough in the theory of evolution to sentence someone to prison for the rest of his life. It is a biological principle that has literally been tested thousands of times with various experiments that support the idea of how species change over time.

Scientists were able to pinpoint the source of the infection was Donald McClellan due to the rapid evolution of the HIV virus. The HIV virus genetic sequence changes much more rapidly than most other organisms DNA sequences because it lacks many of the error correcting methods most eukaryotic cells possess. This results in changes accumulating much more quickly for HIV than in your own cells. This is also partly why developing medications to aid in treating HIV infections is so difficult, since a medicine that works on a strain today will often only work for a short period of time before it is ineffective. Drug research is an expensive and time consuming endeavor, and it isn't profitable or sensible for pharmaceutical companies to work on getting drugs approved that only remain viable for a few weeks or months.

A similar process also happens with the influenza virus, which is the reason why a new version of the flu vaccine is produced each year. The vaccine you received last year may not be as effective in preventing an infection the following year because of alterations to the genetic code of the virus. Some scientists have facetiously said that all recipients of the flu vaccine should sign an agreement that says they believe in the theory of evolution. Although this isn't likely to occur, it reinforces the idea that a yearly flu vaccine is only necessary because organisms are capable of evolving.