High prevalence of syphilis-HIV co-infection at four hospitals of the city of Buenos Aires, Argentina.

A cross-sectional anonymous study of 261 STD (sexually transmitted diseases) outpatients and 288 outpatients from other hospital departments was conducted at four major city hospitals in Buenos Aires. High prevalence of human immunodeficiency virus (HIV) (14.5%) and syphilis (30.2%) was noted. Fifty-two persons were diagnosed with both HIV and syphilis. Of the 87 HIV cases observed, 52 (59.7%) were co-infected with syphilis. Stratified analysis by gender showed that the prevalence of HIV, syphilis and HIV/syphilis co-infection was significantly (p < 0.001) higher in men than women (HIV: 20.1% vs. 4.6%; syphilis: 39.3% vs. 17.4%; co-infection: 13.6% vs. 1.7%). Integrated HIV/STD intervention programs and more effective surveillance are required in Argentina.

[Syphilis and pregnancy. Prenatal control, seroprevalence and false biological positives]. / Sifilis y embarazo. Control prenatal, seroprevalencia y falsos biológicos positivos.

Syphilis may be transmitted vertically, especially if the mother is in an early stage with a high bloodstream treponema concentration, although it may also be transmitted to a lesser degree in late latency, when non-treponemic serology may become negative spontaneously with persistence of treponemic serology. The prenatal control for syphilis is routinely carried out by means of a non-treponemic reaction such as VDRL or rapid plasma reagin (RPR) which, when positive, should be confirmed by treponemic techniques such as fluorescent treponemal antibody absorption (FTA-abs) and/or hemagglutination (MHA-Tp). Prevalence of syphilis should be defined on the basis of positive treponemic reactions. To define the seroprevalence and the validity of these control guidelines, 1,056 pregnant women attending the Hospital de Clínicas for their initial control were evaluated by means of serological treponemic and non-treponemic methods. Serological results disclosed 4 distinct groups. Group 1 (n = 17 or 1.61%) presented both types of reactive tests, while Group II (n = 22 or 2.08%) only presented reactive treponemic tests, and both groups were seroreactive for syphilis. Group III (n = 7 or 0.66%) only showed reactive non-treponemic tests, which were considered biological false-positive (BFP) reactions. Five of them were reactive for antiphospholipid antibodies. Group IV (n = 1,010 or 95.65%) fell to present serological evidence of syphilis. To conclude: 1) global seroprevalence in this population was 3.69%; 2) since 2.08% of pregnant seroreactive mothers had not been detected by routine screening, it would be advisable to perform simultaneous treponemic and non-treponemic techniques for prenatal control. 3) This methodology should identify the BFP tests in the same screening.

[The impact of HIV infection on the incidence of syphilis and gonorrhea at a university hospital (1985-1994)]. / El impacto del HIV sobre la incidencia de sífilis y gonorrea en un Hospital Universitario (1985-1994).

Syphilis and gonorrhea are two sexually transmitted diseases (STD) which still persist in spite of the existence of effective treatment. In this paper the incidence of these two diseases was evaluated between 1985-1994, a decade during which the problem of HIV infection arose. Every patient who attended the STD Program at the Hospital and was suspected of having syphilis and/or gonorrhea was clinically evaluated and was subjected to the following tests: a) search for Neisseria gonorrhoeae (Ng) and penicinilase producers (PPNG) identification, b) search for Treponema pallidum (Tp) by darkfield microscopy, c) serological studies for syphilis. From 1985 to 1991 the average of positive cases for Ng was 14.8% while from 1992 to 1994 it was 4.0% (p < 0.0001) showing a dramatic decrease between 1991 and 1992. PPNG increased from 8.7% in 1985 to 44.6% in 1988 and then slowly decreased down to 26.9% in 1994. From 1985 to 1990 the average of positive darkfield examinations was 20.7% while from 1991 to 1994 it was 12.2% (p < 0.0001). Between 1985 to 1988 syphilis serological studies showed 45.7% positive cases dropping to 34.3% between 1989 and 1994 (p < 0.0001). HIV infection appearance had a wide repercussion throughout the world generating behavioral and sexual habit changes which have probably helped to prevent these two STD. Gonorrhea incidence was also influenced by the appearance of new effective treatments, even against PPNG, such as fluorated quinolones and third generation cephalosporines. The population studied belongs to the most crowded area in Argentina, so that these observations should not be extrapolated to the rest of the country.

Effects of complement depletion in experimental chagas disease: immune lysis of virulent blood forms of Trypanosoma cruzi.

In mice infected with virulent blood (trypomastigote) forms of Trypanosoma cruzi, complement depletion with cobra venom factor caused a marked exacerbation of the disease evidenced by significantly increased parasitemia levels and early mortality as compared with those of untreated infected animals. The effect was greater in mice receiving cobra venom factor on day 7 postinfection, i.e., at the time when the parasites had had time to localize and multiply in the tissues and appeared in the circulation in appreciable numbers. The possibility that complement participates in host defense against T. cruzi infection through a mechanism involving immune lysis was explored in vitro. T. cruzi trypomastigotes were found to undergo immune lysis in sera of patients with chronic Chagas' disease, in sera of immunized mice, and in solutions containing both immune mouse gamma globulin and a source of active complement. This phenomenon failed to take place either in the absence of complement or after complement inactivation by heat or utilizing complement inactivators. The lytic capacity of heated sera was restored by the addition of active complement to the system. During the immune lysis of T. cruzi blood forms, complement was activated in human sera via both the classical and the alternate pathways. In mouse sera, activation followed at least the alternate pathway.