Ethics of screening for asymptomatic herpes virus type 2 infection

The ethics of screening people for asymptomatic herpes virus type 2 infection (HSV-2) has recently been a subject of controversy in the British Medical Journal (BMJ). An article on the matter was published in the BMJ1 but its conclusions were subsequently challenged by a response letter, published in the online section of the same journal.2

Having acknowledged that commercial tests for herpes simplex virus are now widely available and some experts have advocated screening, the authors of the article asked whether screening can be ethical when false positive results occur, many infected people are asymptomatic, and no cure is available?

Besides these points, the authors also argued that despite the fact that considerable concern has been expressed that the world is in the grip of an HSV-2 epidemic,3 these claims could be overstated. They pointed to data from the United States, which, despite the fact that it was claimed to be based on two samples representative of the general population, might have selection problems.4,5 Also, they noted the fact that the absolute rise in prevalence from 16.8% to 21.7% is often expressed as a rise of 30%, which sounds unduly alarming. They added that data from low income countries are usually selected from high risk populations and in Europe they suggested that seroprevalence seems to be falling.

In response to the article, Drs Cohen, Barton and Lawson raised a number of points. They stated that whilst the authors had limited their analysis to HSV, it must be noted that asymptomatic individuals are offered screening for other incurable conditions, by tests which are not 100% specific or sensitive, such as HIV and Hepatitis B and C, all of which have far worse clinical outcomes than genital HSV-2 infection.

They also stated the article suggests that the only practical way of identifying individuals with asymptomatic HSV infection is using serological tests. However, PCR (Polymerase Chain Reaction) techniques have been developed and although not yet commercially available, are already employed for research methodology and could become a useful addition to serological diagnosis.

Whilst they agreed with the authors' observation that a common reason for not testing opportunistically is because of adverse psychological outcomes in those who discover they have the infection, they added that there is evidence that being diagnosed with asymptomatic infection increases the awareness among individuals of symptomatic recurrences which were previously unnoticed.6 A further benefit, not explored in the original article, is that screening asymptomatic patients would determine if they are eligible to participate in the current studies investigating prophylactic HSV-2 vaccines. They argued that the potential benefit for the individual who is seronegative and for the public health may be much enhanced if an effective vaccine was available.

The authors of the original article and the response letter did agree that the issue is complex and that individual health care providers need to evaluate the usefulness and cost effectiveness of this test. Ultimately the authors of the response believe that testing asymptomatic individuals can be ethically justified, providing it is appropriately offered to informed individuals with adequate discussion and subsequent management. They added that, "in the end, it is the patients' choice, not ours, as to whether they take the test."

References

1. Krantz I et al. Ethics of screening for asymptomatic herpes virus type 2 infection. BMJ 2004; 329: 618-621.

2. Cohen CE et al. Screening for asymptomatic HSV 2 infection is ethically justified. BMJ.com http://bmj.bmjjournals.com/cgi/eletters/329/7466/618#74673.

3. Corey L, Handsfield HH. Genital herpes and public health. Addressing a global problem. JAMA 2000;283: 791-4.

4. Fleming DT et al. Herpes simplex virus type 2 in the United States, 1976 to 1994. N Engl J Med 1997;337: 1105-11.

5. Johnson RE et al. A seroepidemiologic survey of the prevalence of herpes simplex type 2 infection in the United States. N Engl J Med 1989;321: 7-12.

6. Corey L. The current trend in genital herpes. Progress in prevention. Sex Transm Dis 1994; 21 (S38-44).