persons present no risk to nonsexual household contacts (9). The present case undoubtedly represents infection acquired in West Africa since illness began before the patient's arrival in the United States. The patient has had no known activities that would have exposed others in this country to HIV-2.

Because of the reports of HIV-2 infection in West Africa and Europe, CDC and the Food and Drug Administration (FDA) initiated surveillance for HIV-2 in the United States in January 1987. To date, CDC, FDA, and collaborating investigators have screened 22,699 serum samples with anti-HIV-2 EIA (10). Of these specimens, 14,196 (63%) were from individuals whose activities placed them at increased risk for HIV-1 infection and who would, therefore, potentially be at risk for HIV-2 infection. The remaining 8,503 were from asymptomatic blood donors randomly selected from three areas of the United States, two of which have reported large numbers of AIDS patients. Overall, 35 (0.2%) of the serum samples were reactive by anti-HIV EIA using HIV-2 antigens but not by anti-HIV EIA using HIV-1 antigens. However, none of these EIAs could be confirmed when tested by HIV-2-specific Western blot. An additional 70 (0.3%) of the samples were reactive by Western blot with gag, pol, and env antigens of both HIV-1 and HIV-2. All of the dually reactive specimens were from individuals whose activities placed them at increased risk for HIV-1 infection. None were from the randomly selected blood donors. Sera from these dually reactive subjects were studied for the presence of type-specific neutralizing antibody to HIV-1 or HIV-2, antibody to synthetic peptides specific for HIV-1 or HIV-2 (Genetic Systems Corporation, Seattle, Washington [research test kit]), or HIV-1 and HIV-2 DNA by DNA amplification (1). Sixty of the subjects were shown to be infected with HIV-1 but not HIV-2. Ten are still under investigation.

It is reassuring that HIV-2-specific tests on sera from 22,699 persons, including 8,503 randomly selected U.S. blood donors, failed to reveal HIV-2 infection. However, the occasional presence of this virus in the United States, as in Europe, should be anticipated. The anti-HIV-1 EIA tests currently used for screening all U.S. blood donors are estimated to detect 42% to 92% of HIV-2 infections (4,11). Surveillance for HIV-2 in the United States is being continued to monitor the frequency of infection. Because the modes of transmission of HIV-1 and HIV-2 are similar, preventive measures for these related viruses are the same (12).

References

1. Ou C-Y, Kwok S, Mitchell SW, et al. DNA amplification for direct detection of HIV-1 in DNA of peripheral blood mononuclear cells. Science 1988;239:295-7.

2. Clavel F, Guétard D, Brun-Vézinet F, et al. Isolation of a new human retrovirus from West African patients with AIDS. Science 1986;233:343-6.

3. Brun-Vézinet F, Rey MA, Katlama C, et al. Lymphadenopathy-associated virus type 2 in AIDS and AIDS-related complex: clinical and virological features in four patients. Lancet 1987;1:128-32.

4. Clavel F, Mansinho K, Chamaret S, et al. Human immunodeficiency virus type 2 infection associated with AIDS in West Africa. N Engl J Med 1987;316:1180-5.

5. Brun-Vézinet F, Rey MA, Dazza MC, et al. LAV-2/HIV-2 infection: clinical, epidemiological and virological features [Abstract no. THP.33]. In: Abstracts of the third international conference on acquired immunodeficiency syndrome (AIDS). Washington, DC: US Department of Health and Human Services, Public Health Service, World Health Organization, 1987:169. 6. Antunes F, Odete Santos Ferreira M, Lourenco MH, Costa C, Pedro M. HIV infections in rural areas of West Africa (Guinea Bissau) [Abstract no. THP.88]. In: Abstracts of the third international conference on acquired immunodeficiency syndrome (AIDS). Washington, DC: US Department of Health and Human Services, Public Health Service, World Health Organization, 1987:178.

7. Katlama C, Harzic M, Kourouma K, Dazza MC, Brun-Vézinet F. Seroepidemiological study of HIV1 and HIV2 infection in Guinea-Conakry [Abstract no. THP.75]. In: Abstracts of the third international conference on acquired immunodeficiency syndrome (AIDS). Washington, DC: US Department of Health and Human Services, Public Health Service, World Health Organization, 1987:176.

8. Clavel F. HIV-2, the West African AIDS virus. AIDS 1987; 1:135-40.

9. Friedland GH, Saltzman BR, Rogers MF, et al. Lack of transmission of HTLV-III/LAV infection to household contacts of patients with AIDS or AIDS-related complex with oral candidiasis. N Engl J Med 1986; 314:344-9.

10. Schochetman G, Schable CA, Goldstein LC, Epstein J, Zuck TF. Screening of U.S. populations for the presence of LAV-II [Abstract no. THP.52]. In: Abstracts of the third international conference on acquired immunodeficiency syndrome (AIDS). Washington, DC: US Department of Health and Human Services, Public Health Service, World Health Organization, 1987:172.

11. Denis F, Leonard G, Mounier M, et al. Efficacy of five enzyme immunoassays for antibody to HIV in detecting antibody to HTLV-IV. Lancet 1987; 1:324-5.

12. Public Health Service. Surgeon General's report on acquired immune deficiency syndrome. Washington, DC: US Department of Health and Human Services, Public Health Service, 1986.

Current Trends

Continuing Increase in Infectious Syphilis United States

Through the first 46 weeks of 1987, 31,323 cases of infectious (primary and secondary) syphilis were reported to CDC through the MMWR Morbidity Surveillance System. This total exceeds the number of cases reported for the same period in 1986 by 32%. The projected annual incidence of infectious syphilis for 1987 is 14.7/100,000, which would be the highest rate since 1950. While 56% of all cases and 83% of the increase were reported from Florida, New York City (NYC), and California, 25 of the other 49 reporting areas also had increases. Nine areas had absolute increases of over 100 cases; in two of these areas, the relative increases were over 100% (Table 1). With the exception of Oregon and Connecticut, areas with high incidence rates experienced the greatest increases. Texas, with a 22% decrease in reported cases, and Louisiana, with a 9% decrease, were notable exceptions to the overall pattern of increase.

Fourteen areas reporting increases and five reporting decreases during the first 8 months of 1987 were asked to provide data on patients' race, sex, and sexual preference for further analysis. Overall, the areas providing this supplementary information contain 51% of the U.S. population and 79% of the syphilis cases reported through the first 46 weeks of 1987.

In the 14 areas reporting increases (13 states and NYC), relative increases were greatest for females and heterosexual males of all racial/ethnic backgrounds (Table 2). The greatest absolute increases occurred among blacks. The increase for males occurred among heterosexual males, and the decrease among homosexual/ bisexual males occurred primarily among white males (1). Exceptions to this overall

pattern occurred in Connecticut and Georgia. In Connecticut, the relative and absolute increases were greatest among white heterosexual males. In Georgia, increases occurred only among white and black males, and a substantial portion of the increase appeared to be among homosexual/bisexual males.

In the five states reporting decreases, the only exception to the overall pattern of decrease occurred among white females. The number of reported cases increased by 51% (20 cases) in this group.

The pattern of increase differed among reporting areas. In some areas, such as Philadelphia and Los Angeles, the increase appears to have plateaued in the middle of 1987. However, in other areas, such as NYC, Florida, and Oregon, the increase continued to climb. In still others, such as Pennsylvania (excluding Philadelphia), the increase began during this period.

Reported by: RG Sharrar, MD, M Goldberg, Philadelphia Dept of Public Health. Participating City and State Health Depts and STD Control Programs. Div of Sexually Transmitted Diseases, Center for Prevention Svcs, CDC.

Editorial note: These increases in infectious syphilis not only reverse the downward trend of the past 4 years, they also suggest an important shift in the epidemiology of the disease in the United States. As infectious syphilis has decreased among homosexual and bisexual males, largely because of changes in sexual behavior due to AIDS, a sizeable increase has occurred among heterosexuals. A similar shift was documented earlier in two small outbreaks (2,3).

While the cause of this increase is unknown, several hypotheses have been proposed. First, anecdotal reports from persons interviewing syphilis patients and their sexual partners indicate that prostitution in which nonintravenous drugs (especially "crack" cocaine) are exchanged for sex may be partially responsible for outbreaks of syphilis as well as other sexually transmitted diseases. A review of TABLE 1. Reporting areas with the largest absolute increases in infectious syphilis – United States, weeks 1-46, 1987

*Per 100,000; based on 1985 Bureau of the Census projections.

Syphilis - Continued

records of interviews in Philadelphia showed that the proportion of patients associated with both prostitution and drug use increased significantly between 1985 and 1987 (4).

Second, some investigators have suggested that routine use of spectinomycin (which does not appear to cure incubating syphilis [5,6]) in areas where a sizeable proportion of gonorrhea infections are caused by B-lactamase-producing organisms may explain the increase in infectious syphilis.* Events in NYC, Florida, and Los Angeles are compatible with this theory; however, for several other areas with sizeable increases in reported syphilis, spectinomycin was not in common use before the increases began. While this mechanism may play a role in some areas, it alone cannot account for the nationwide increase.

Third, a decrease in the resources available for syphilis control programs has been suggested as a contributing factor. Twenty reporting areas provided data on the number of staff available for syphilis control during 1985 and 1986. Ten of these areas

*Parenteral penicillin regimens used to treat gonorrhea have been shown to cure incubating syphilis acquired at the same time as gonorrhea infection (7).

*Arizona, Baltimore, Connecticut, North Carolina, Oregon, and Philadelphia.

TABLE 2. Cases of infectious syphilis from 14 reporting areas,* by race, sex, and sexual preference - United States, January-August, 1987

*Arizona, California, Connecticut, Florida, Georgia, Maryland, Massachusetts, Mississippi, North Carolina, Oregon, Pennsylvania, South Carolina, Tennessee, and New York City. Data for California (other than Los Angeles and San Francisco) are for the first 6 months only. *Males naming at least one male sexual partner were classified as "homosexual/bisexual"; those not naming any were classified as "heterosexual." Overall, 87% of males were interviewed in 1986 and 85%, in 1987. Over 80% of males were interviewed in all reporting areas except New York City, where 55% were interviewed in 1986 and 45%, in 1987.

Syphilis Continued

reported increases in the number of persons interviewing patients with early syphilis between 1985 and 1986; four reported no change; and six reported decreases. Areas reporting increases in total syphilis morbidity were somewhat more likely to report a decrease in the number of interviewers; however, the association was not statistically significant.

The increases in infectious syphilis among females and heterosexuals are disturbing for three reasons. First, an increase in the number of females with syphilis will likely be followed by increased morbidity and mortality from congenital syphilis. Second, the marked increase among inner-city, heterosexual minority groups suggests that high-risk sexual activity is increasing in these groups despite the risk of HIV infection, which is already elevated because of the high prevalence of intravenous drug abuse. Third, studies in Africa and in the United States suggest that genital ulcer diseases such as primary syphilis increase the risk of HIV transmission (8,9). References

1. Landrum S, Beck-Sague C, Kraus S. Racial trends in syphilis among men with same-sex partners in Atlanta, Georgia. Am J Public Health 1988;78:66-7.

2. Centers for Disease Control. Early syphilis - Broward County, Florida. MMWR 1987;36:221-3. 3. Lee CB, Brunham RC, Sherman E, Harding GKM. Epidemiology of an outbreak of infectious syphilis in Manitoba. Am J Epidemiol 1987;125:277-83.

4. Rolfs RT, Goldberg M, Sharrar RG. Outbreak of early syphilis in Philadelphia. Presented at the 115th annual meeting of the American Public Health Association and related organizations, New Orleans, Louisiana, October 18-22, 1987.

5. Petzoldt D. Effect of spectinomycin on T. pallidum in incubating experimental syphilis. Br J Vener Dis 1975;51:305-6.

6. Rein MF. Biopharmacology of syphilotherapy. J Am Vener Dis Assoc 1976;3:109-27.

7. Schroeter AL, Turner RH, Lucas JB, Brown WJ. Therapy for incubating syphilis: effectiveness of gonorrhea treatment. JAMA 1971;218:711-3.

8. Quinn TC, Glasser D, Matuszak DL, et al. Screening for human immunodeficiency virus (HIV) infection in patients attending sexually transmitted diseases clinics: risk factors and correlates of infection. Presented at the International Society for STD Research, Atlanta, Georgia, August 2-5, 1987.

9. Cameron DW, Plummer FA, Simonsen JN, et al. Female to male heterosexual transmission of HIV infection in Nairobi. Presented at the International Society for STD Research, Atlanta, Georgia, August 2-5, 1987.

Current Trends

Antigenic Variation of Recent Influenza A(H3N2) Viruses

Analysis of recent influenza A(H3N2) viruses indicates antigenic drift from the previously prevalent strains A/Mississippi/1/85 and A/Leningrad/360/86. One reference variant virus strain, A/Victoria/7/87, was first isolated in Australia in April of this year. A second reference variant, A/Sichuan/2/87, was first isolated in China, also in April. In hemagglutination inhibition tests with antiserum from infected ferrets, antibody to A/Victoria/7/87 reacts poorly with other strains, even though the virus itself is inhibited well by antiserum to A/Mississippi/1/85 (Table 1). Antiserum to A/Sichuan/2/87 reacts at lower titers with viruses such as A/Mississippi/1/85 and A/Leningrad/360/86, which circulated earlier, than it does with A/Sichuan/2/87 anti