Letters to the Editor

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Infant and maternal characteristics for babies who die of HIV/AIDS reflected factors associated with high infant mortality in general, such as low birthweight and short gestation, lower maternal age and education.3 Because most children with perinatally acquired AIDS are born to mothers who are intravenous drug users or the sexual partners of intravenous drug users,4 the characteristics of babies who die of HIV/AIDS more directly reflect characteristics associated with maternal drug use,5'6 rather than characteristics that result from HIV infection. The markedly higher percentage of mothers who were unmarried, especially among black women, and who had received no or late prenatal care emphasizes the challenges that confront efforts to prevent perinatal HIV transmission and to provide services for mothers and infants infected with mV. a Susan Y. Chu., PhD James W. Buhler, MD Martla F. Rogers, MD The authors are with the Division of HIV/ AIDS, Centers for Disease Control, Atlanta, Ga. Direct inquiries to Susan Y. Chu, PhD, Surveillance Branch, Division of HIV/AIDS, Center for Infectious Diseases, Centers for Disease Control, Mailstop E-47, 1600 Clifton Road, NE, Atlanta, GA 30333.

References 1. National Center for Health Statistics. 1985 Linked Birth and Infant Death Data Set. Hyattsville, MD: US Department of Health and Human Services, Public Health Service, 1990. Machine-readable data file. 2. National Center for Health Statistics. Advance report of final mortality statistics,

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1984. Monthly Vital Statistics Report, Vol. 35, No. 6 (Suppl 2). Hyattsville, MD: Public Health Service, September 26, 1986:42-43. DHHS Pub. No. (PHS) 86-1120. 3. Centers for Disease Control. National Infant Mortality Surveillance (NIMS), 1980. MAMWR 1989;38(No. SS-3):1-46. 4. Oxtoby MJ. Perinatally acquired human immunodeficiency virus infection. Pediatr Infect Dis J. 1990;9:609-619. 5. Blanche S, Rouzioux C, Guihard Moscato ML, et al. A prospective study of infants born to women seropositive for human immunodeficiencyvirus type I. NEnglJMed 1989;320:1643-1648. 6. MinkoffHL, McCalla S, Delke I, Stevens R, Selwen M, Feldman J. The relationship of cocaine use to syphilis and human immunodeficiency virus infections among inner city parturient women. Am J Obstet GynecoL 1990;163:521-526.

International Collaboration in a Cluster Investigation In Matamoros, Mexico, a multiagency intemational work group (the Mexican National Institute of Nutrition, the Pan American Health Organization, and the US Centers for Disease Control [CDC]), investigated in 1987 an alleged cluster of children with facial malformations. A link had been suspected between the children's problems and their mothers' possible exposures, during their pregnancies, to polychlorinated biphenyls (PCBs) while they were working at an electronics "maquiladora" (US-Mexican twin assembly plant), where PCB-containing capacitors were used.' The study addressed two questions: (a) had there been expo-

sure to PCBs in these mothers and their children? and (b) did the children constitute a cluster with objectively defined common malformations that should be studied further? Twelve of 20 children were available for study. We interviewed their 11 mothers, asking about their work histories in relation to their pertinent pregnancies, about their symptom histories before and during pregnancy, and about their babies during their newborn periods. We took blood specimens for PCB levels from a study group of 7 children and their 6 mothers and from a comparison group of 5 children and 5 adult volunteers from the school. The blood was shipped frozen to the CDC where PCB determinations were made with gas chromatography. We examined the 12 children for dysmorphologic features (one of us is a geneticistdysmorphologist), using an anomaly checklist that had been tested in a study of congenital PCB exposure in Taiwan.2 Photographs were taken and reviewed by a separate group of dysmorphologists. The maquiladora and company went out of business in 1977; thus it was impossible to retrieve any technical records. Occupational histories suggested maternal exposure to solvents, except for one ofthe mothers who, it turned out, had not worked in the maquiladora. Symptom histories were negative for PCB-associated outcomes, such as chloracne in the mothers and ectodermal dysplastic manifestations in the newborns. Serum PCB levels in the study and comparison group were all under 1 part per billion (ppb), less than

American Journal of Public Health 1077

Letters to the Editor

the mean of 5 to 7 ppb in US populations.3,4 The 12 study children demonstrated various degrees of minor facial anomalies, but no distinctive common features that could define a "case." The results of this study excluded the presence of a cluster of children with a common problem and ruled out significant exposure to PCBs. This was an exercise in what has been tenned reactive epidemiology.5 The focus of such studies is on verifying hazards and health outcomes in responding to community concerns. We assessed both exposure and outcome. Because of our collaboration it was possible to mininmize the bureaucratic problems and carry out the project within a reasonable time frame. Additionally, the concerns of the community could be satisfied. Investigators in developing countries often cannot start on simple projects for lack of resources. Yet there is a great need for such multiagency, bilateral or multilateral studies in these countries in view of the generally higher potential of toxic exposure and disease.6,7 In contrast, researchers in developed countries are often in search of challenging projects, and they must generally contend with low-level environmental exposures, which requires the study of a large number of people and/or for a long time period. Collaborative projects can and should be effective and efficient, can add to the international scientific base, can help develop preventive public health measures, and can assist in transferring technology and in human resources development. These should also be encouraged because they are an important complemental strategy in the World Health Organization's goal of Health for All by the year 2000.8 [ Alvaw Gwza, MD, MPH Oswado Mutchick MD, PhD Jose F. Cordero, MD, MPH Wlbyn W. Burse Alvaro Garza was with the Pan American Health Organization of the World Health Organization in Metepec, Mexico. Osvaldo Mutchinick is with the Instituto Nacional de la Nutricion Salvador Zubiran in Tlalpan, Mexico. Jose F. Cordero and Virlyn W. Burse are with the Centers for Disease Control, US Department of Health and Human Services, Atlanta, Ga. Direct inquiries to Alvaro Garza, MD, MPH, San Francisco Department of Public Health, 101 Grove Street, Room 402, San Francisco, CA 94102.

References 1. Beebe M: Mexico. The border industry. Mallory plant is long gone; some say it left grim legacy. Buffalo News. March 11, 1987. A1(col 1), A4(col 1). 2. Rogan WJ, Gladen BC, Hung KL, et aL

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5. 6.

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Congenital poisoning by polychlorinated biphenyls and their contaminants in Taiwan. Science. 1988;241:334-336. Kimbrough RD. Human health effects of polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs). Annu Rev Pharmacol TaoxcoL 1987;27:87-111. Kreiss K. Studies on populations exposed to polychlorinated biphenyls. Environ Health Perspect. 1985; 60:193-199. Anderson, HA. Evolution of environmental epidemiologic risk assessment. Environ. Health Perspect. 1985;62:389-392. Michaels D, Barrera C, Gacharna MG. Economic development and occupational health in Latin America: new directions for public health in less developed countries. Am J Public Health. 1985;75:536-542. Environmental Health Program, Pan American Health Organization, World Health Organization (WHO). Regional Program on Chemical Safety. XXII Pan American Sanitary Conference. Washington, DC: WHO; 1987. Environmental series 7. Pan American Health Organization, World Health Organization (WHO). Health for aUl by the year 2000: strategies. Washington, DC: WHO; 1980. Official Document 173.

Crack Cocaine, Fellatio, and the Transmission of Holmes et al.I have reviewed the data on heterosexually acquired AIDS in the United States. They state, and we agree, that "drug use, exchange of sex for drugs or money, and early onset of sexual activity in adolescents are increasingly associated with heterosexually transmitted infections and are likely to be very important in heterosexual transmission of HIV in inner-city US populations" (p. 858). The relationship between HIV/AIDS and intravenous drug abuse (IVDA) is well established. Now, as the HIV/AIDS pandemic continues, we have begun to see reports of studies of the relationship between non-IVDA (particularly the smoking of crack cocaine) and the transmission of HIV and other sexually transmitted diseases.2-4 These publications indicate a recognition that non-IVDA may be of particular importance in the spread of disease to the general public. The study of sentinel hospitals reported by St. Louis and colleagues5 did not link specific risk factors with HIV serostatus, but it did point out the potential for spread of the infection in many, if not all, sectors of society. In particular, the article stated that "uninfected people of either sex who persist in high-risk sexual activities or drug use in these (high seroprevalence) areas are extremely likely to come into contact with a person infected with HIV-1" (p. 217).

In light of all this, there is a need to examine certain questions related to the sexual behaviors practiced by non-IVDAs. Specifically, we have anecdotal reports that oral sex constitutes a large proportion of the heterosexual activity involving crack users. There is reason to believe that steady crack use renders many men impotent so that vaginal or anal intercourse becomes impossible. Oral sex is practiced but may not lead to orgasm for these men; thus the amount of semen that is transmitted to the active partner is limited. However, it cannot be assumed that oral sex between crack users is safe. We need to know more about how the virus might be transmitted from mouth to penis, for example, whether such transmission occurs in the presence or absence of oral or penile lesions. Poor oral hygiene and burns in the mouth may enhance viral concentration in saliva. Another question raised by oral sex in the absence of erection and/or ejaculation is whether current prevention recommendations are applicable. The widespread distribution of condoms to crack users is recommended by the Fullilove et al.,6 for example. However, successful condom use is not feasible in the absence of an erection. Crack cocaine use poses many challenges. Research must be conducted if we are to understand the relationship between HIV transmission and sexual contact between crack cocaine smokers and other nonintravenous drug abusers, and if we are to develop preventive and interventive techniques that may slow the spread of HIV in these populations. ] Harry W. Haverkos, MD Eizabeth Steel, MSW Harry W. Haverkos and Elizabeth Steel are with the National Institute on Drug Abuse, Rockville, Md. Direct inquiries to Ms. Steel, 5600 Fishers Lane, Room 1OA-38 (Parklawn Building), Rockville, MD 20857.

References 1. Holmes KK, Karon JM, Kreiss J. The increasing frequency of heterosexually acquired AIDS in the United States, 1983-88. Am JPublic Health. 1990;80:858-863. 2. Fuililove MT, Fullilove RE. Intersecting epidemics: black teen crack use and sexually transmitted disease.JAm Med WomAssoc.

1989;44:146-153. 3. Chiasson MA, Stoneburner RL, Hildebrandt DS, Telzak EE, Jaffe HW. Heterosexual Transmission of HIV Associated with the Use of Smokable Freebase Cocaine (Crack). Poster session at the 6th International Conference on AIDS, San Francisco, June 1990. Abstract Vol. 1: p. 272. 4. Rolfs RT, Goldberg M, Sharrar RG. Risk

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