versity, Hamilton, Ont., are fortunate that peer evaluation is a major component of the evaluation process. Students are encouraged by their colleagues to keep their interests and activities varied and balanced. However, such pursuits become more difficult as the clinical component of the educational experience increases. Would it be unreasonable to replace or combine educational teaching sessions with physical activities? I do not believe that the educational experience would be jeopardized by replacing events such as "drug lunches" with opportunities to engage in physical fitness pursuits. In the long run doctors would not only be healthier but also be more credible role models for their patients. As long as medical programs do not recognize the importance of the physical well-being of their students, the physical inactivity of many physicians will continue. Marianne Talman, MSc Clinical clerk McMaster University Hamilton, Ont.

One possible explanation for the lesser physical activity of physicians versus the general population could be related to interpretation of the literature. It is well documented that physical activity reduces blood pressure and the levels of cholesterol and glucose. Such activity also imparts a sense of well-being. However, I am unaware of any single documentation in the literature that physical activity in itself, without consideration of its effects on other risk factors, has clear-cut beneficial primary preventive effects in terms of cardiovascular disease. In other words, if the blood pressure and the levels of cholesterol and glucose are good, what additional effect would physical activity have? Or, if these values are elevated, what effect would physical activity have other than lowering them? Can I 1196

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not control my risk factors equally well, with less time involvement, by means other than physical activity? I still believe that the literature puts the onus on those physicians or scientists who advocate physical activity for the sake of reducing these risk factors to show, through at least one wellcontrolled, prospective study in which blood pressure and levels of cholesterol and glucose have been equalized, that physical activity is of benefit in reducing the risk of cardiovascular disease. Thomas Baitz, MD, FRCPC 1 13-820 McConnell Ave. Cornwall, Ont.

[The authors respond.] We thank Ms. Talman for her observations and the additional insights they offer. We agree wholeheartedly with all that she says, including the notion that providing opportunities for physical activity in medical students' schedules would be worth while. Dr. Baitz raises a number of interesting points, but we are puzzled that he has chosen to focus upon the prevention of coronary heart disease, since this was not the topic of our article. He is correct that physical activity exerts its beneficial effects on health through a variety of metabolic, hemodynamic and physiologic effects, a few of which he has mentioned. We are not aware of any other single intervention with such a wide variety of favourable health influences. Baitz seems to believe that relying upon good genes and good luck for these effects is sufficient. We do not agree that this is a sound strategy for achieving physiologic hygiene. The purpose of our study was to examine the matter of physicians as role models for their patients. We view physical activity as a form of preventive mainte-

nance, a positive step toward the promotion and maintenance of health. The long-term physiologic benefits of exercise can be achieved and maintained with only a modest input of time. Baitz seems to believe the time input to be excessive and would prefer a quicker fix. We believe that the physician who encourages patients to spend as little time as possible at health promotion, either by word or by example, serves them ill. Paul H. Gaertner, MD Intern St. Paul's Hospital Whitmer B. Firor, MD Department of Medicine Lindsay Edouard, MB, MFCM Department of Community Health and Epidemiology University of Saskatchewan Saskatoon, Sask.

HIV infection among Quebec women giving birth to live infants I apologize to Dr. Catherine A. Hankins for suggesting in my

earlier letter (Can Med Assoc J 1991; 145: 198-199) no prior knowledge of the study by Blanche and associates and the HIV [human immunodeficiency virus] Infection in Newborns French Collaborative Study Group. ' I caution her, however, regarding the use of absolute or universal statements.

In her reply (ibid: 199) Hankins suggests that I had not read the discussion in that report. I most certainly did read it. The authors considered the relation of breast-feeding to HIV infection important enough to include it in the abstract of their paper. Indeed, in their discussion they state: "Despite the small number of infants observed this difference is significant and tends to suggest that breast feeding may have a role in the transmission of the virus from mother to infant." The LE 15 NOVEMBRE 1991

1991 Year Book of Pediatrics,2 abstracting this paper, also draws attention to this association. The demonstration that HIV could be transmitted in breast milk from a previously HIV-negative mother who had been transfused post partum with HIV-positive blood was a brilliant piece of serendipitous research,3 which was later confirmed.4 To suggest that this is the only way in which HIV infection from breast milk may occur is misleading to say the least, particularly since our knowledge of other retroviruses has demonstrated that such is not the case. Because of the important role of breast-feeding in the nutrition of developing countries it is important not to abandon this practice lightly. This, however, is not an argument against HIV testing, particularly in the developed world, where alternative, safe feeding methods are available. It is in the best interests of infants that all pregnant women in Canada be tested for HIV for the reasons I have outlined in previous correspondence, which include an increasing incidence of infection, the infectious nature of the disease and the possibility of prevention. The measures outlined by Angell5 appear to cover the situation adequately. She states: "I believe that, on balance, systematic tracing and notification of the sexual partners of HIV-infected persons and screening of pregnant women, newborns, hospitalized patients, and health care professionals are warranted." To this I can only say Amen! Let us cease procrastinating and get on with the job of epidemic containment.

Dr. Parker cautions me regarding "the use of absolute or universal statements," giving as examples two statements in which, unfortunately, I am misquoted. The first instance is of only minor relevance. I did not state that Parker had not read the discussion in the report by Blanche and colleagues, since I could not make such a claim without questioning him directly. Rather, I borrowed Parker's own terminology when I suggested that he did "not appear to have read the discussion." It is now clear that both of us have read the discussion in question but that we have differing opinions regarding the strength of the evidence presented by the study, evidence that remains to be corroborated in the scientific literature. The second instance in which there appears to be some misunderstanding of my intent is when Parker states that I misleadingly suggest that the only way in which HIV infection from breast milk can occur is when a previously HIV-negative mother has been transfused post partum with HIVJames E. Parker, MB, FRCPC 303-2151 McCallum Rd. positive blood. In my response Abbotsford, BC (Can Med Assoc J 199 1; 144: 955) to a previous letter from Parker References (ibid: 954-955) I indicated that 1. Blanche S, Rouziouxc C, Moscato MLG the only cases of HIV transmiset al and the HIV Infection in New- sion through breast-feeding that

have been documented worldwide have occurred when the mother did not have HIV infection during pregnancy and that it has not been demonstrated that breast-feeding poses an incremental risk to infants who have acquired antibodies transplacentally. This does not mean that further research on this crucial question is not required. On the contrary, obtaining a scientifically valid answer is viewed as a major priority by the Global Programme on AIDS of the World Health Organization' and by researchers, clinicians and public health specialists in both developed and developing countries. The field of scientific endeavour regarding maternofetal transmission of HIV is dynamic and exciting. Recent evidence suggests that the rate of mother-tochild transmission of HIV may be as low as 12.5%,2 and a groundbreaking polymerase chain reaction test for the virus itself in infants has just been developed at the Federal Centre for AIDS, Ottawa.3 Rapid validation of this microtechnique on a larger scale in several countries will open the door to definitive studies elucidating the role of breast-feeding in HIV transmission. It appears unlikely that Parker and I can reach agreement at this time on the issues we have been discussing. As new information becomes available a different light may be cast on the topic of breast-feeding and the risk of HIV transmission and its implications for the discussion regarding the screening of all pregnant women in Canada for HIV infection. In the meantime, I reiterate that HIV testing is available free in Canada for any woman, pregnant or not, who is capable of providing informed consent for the procedure after adequate pretest counselling. With increasing evidence that early intervention may be beneficial for people with HIV infection clinicians should

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2. 3.

4.

5.

borns French Collaborative Study Group: A prospective study of infants born to women seropositive for human immunodeficiency virus type 1. N Engi JMed 1989; 320: 1643-1648 Oski FA, Stockman JA: The Year Book of Pediatrics, Mosby Yr Bk, St Louis, 1991: 70-73 Ziegler JB, Cooper DA, Johnson RD et al: Postnatal transmission of AIDS associated retrovirus from mother to infant. Lancet 1985; 1: 896-898 Lepage P, Van de Perre P, Carael M et al: Postnatal transmission of HIV from mother to child [C]. Lancet 1987; 2: 400 Angell MA: A dual approach to the AIDS epidemic [E]. N Engl J Med 1991; 324: 1498-1500

[Dr. Hankins responds:]

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versity, Hamilton, Ont., are fortunate that peer evaluation is a major component of the evaluation process. Students are encouraged by their colleague...
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