Silvia M. Montano

HIV-1 sexually transmitted infections and sexual behavior trends among men who have sex with men in Lima Peru.

Objective:To assess and estimate trends in HIV, sexually transmitted infections (STIs), and sexual behavior among men who have sex with men (MSM) in Lima, Peru. Design:Second-generation HIV sentinel surveillance surveys conducted in 1996, 1998, 2000, and 2002. Methods:Adult men reporting sex with at least 1 man during the previous year were eligible to participate. Sexual behavior and serum HIV-1 and syphilis antibodies were assessed. HIV seroincidence was estimated by a sensitive/less-sensitive enzyme immunoassay strategy. Rectal and pharyngeal swabs for Neisseria gonorrhoeae culture and a first-void urine sample for urethral leukocytes for presumptive diagnosis of urethritis were obtained. Herpes simplex virus 2 (HSV-2) antibodies were measured in 2002. Results:Although HIV prevalence increased from 18.5% to 22.3% from 1996 through 2002, bacterial prevalence declined significantly for syphilis (16.0% to 12.4%), early syphilis (8.6% to 3.4%), and rectal gonorrhea (5.1% to 0.2%). High HIV seroincidence was estimated, with the lowest (4.8%) incidence in 1998. In 2002, HSV-2 seroprevalence was 51.0%. After adjustment for age, education, and self-reported sexual identity, our data suggest that a yearly increase by 6% in the prevalence of HIV occurred among MSM in Lima, with a corresponding decline in syphilis (by 9%), early syphilis (by 18%), and rectal gonorrhea (by 64%). Condom use during last sexual intercourse increased by 26% each year with the most recent male steady partner and, among non-sex workers, by 11% with the most recent casual partner. Conclusions:HIV continued to spread among MSM in Lima even when a decline in bacterial STIs and increase in condom use were estimated to occur. Intensification of medical and behavior prevention interventions is warranted for MSM in Peru.

Association of herpes simplex virus type 2 infection and syphilis with human immunodeficiency virus infection among men who have sex with men in Peru.

BACKGROUND We evaluated associations between human immunodeficiency virus (HIV) infection, herpes simplex virus type 2 (HSV-2) infection, and syphilis among men who have sex with men (MSM) in Peru. METHODS A surveillance survey of 3280 MSM was conducted; sexual behavior was assessed with a structured computer-assisted self-interview, and serum antibody testing was performed for HIV, HSV-2, and Treponema pallidum. RESULTS HIV, HSV-2, and syphilis seroprevalences of 13.9%, 46.3%, and 13.4% were detected, respectively. HSV-2 seroprevalence was twice as high in HIV-infected subjects (80.5%) than it was in HIV-uninfected subjects (40.8%) (P < .01), and HSV-2 seropositivity (adjusted odds ratio [AOR], 5.66) was found to be strongly associated with HIV infection. In addition, homosexual self-definition (AOR, 3.12), exchange of sex for money (AOR, 1.61), unprotected sex (no condom) (AOR, 2.81), history of sex work (AOR, 1.89), oral receptive sex (AOR, 1.43), and cocaine use before/during sex (AOR, 2.53) within the preceding 6 months, as well as such sexually transmitted infections (STIs) and STI syndromes as proctitis (AOR, 2.80), genital ulcer disease (GUD) (AOR, 2.06), prior syphilis (AOR, 2.64), genital warts (AOR, 1.70), and self-reported STIs within the preceding 6 months (AOR, 1.61), were also found to be significant predictors of HIV infection. CONCLUSIONS We found a strong association between HSV-2 seropositivity and HIV infection. Intervention measures against GUD due to HSV-2 infection and syphilis, such as routine testing, early detection, HSV-2 suppressive treatment, and condom distribution, need to be enhanced as part of STI prevention strategies at a national level to effectively reduce HIV infection among MSM in Peru.

Molecular Epidemiology of HIV Type 1 in Ecuador, Peru, Bolivia, Uruguay, and Argentina.

Surveillance for HIV infection among people at increased risk was conducted in five countries in South America. Seroprevalence studies were conducted in more than 36,000 people in Ecuador, Peru, Boliva, Uruguay, and Argentina, along with genetic analysis of the HIV-1 strains. In all countries, the prevalence of HIV-1 among men who have sex with men (MSM) was high (3-30%), whereas the prevalence among female commercial sex workers (FCSMs) was low (0.3-6%). By envelope heteroduplex mobility assay, subtype B predominated in MSM communities and in FCSWs in Ecuador, Bolivia, and Peru. A new genetic screening assay, the multiregion hybridization assay for subtypes B and F (MHA-bf), was developed to improve large-scale genetic screening in South America. MHA-bf can screen four regions of the genome for subtype B or subtype F, and thus can detect most recombinants. The sensitivity of MHA-bf when applied to a panel of pure subtypes and CRF12_BF was 100%, and 88% of unique recombinants were also detected as recombinant. Using MHA-bf, more than 80% of samples from Ecuador, Peru, and Bolivia were classified as pure subtype B, whereas in Uruguay and Argentina this proportion was only 30 to 40%. BF recombinants were the most prevalent form of HIV-1 in Uruguay and Argentina. Subtype B is the most common subtype in countries lacking injecting drug use (IDU) epidemics, whereas BF recombinants are more common in countries where extensive IDU epidemics have been documented, suggesting the ontogeny of recombinant strains in particular risk groups in South America.

Seroprevalence of and risk factors for HIV-1 infection among South American men who have sex with men

Objectives: Sex among men constitutes an important route of transmission for HIV type 1 (HIV-1) in Latin America. Seeking better understanding of risk behaviours in this region, we determined the seroprevalence, potential risk factors, and geographic distribution of HIV-1 among groups of men who have sex with men (MSM). Methods: Seroepidemiological, cross sectional studies of 13 847 MSM were conducted in seven countries of South America during the years 1999–2002. Volunteers were recruited in city venues and streets where anonymous questionnaires and blood samples were obtained. HIV-1 infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot (WB) confirmatory tests. Results: HIV-1 seroprevalence varied widely (overall 12.3%, range 11.0%–20.6%). The highest HIV-1 seroprevalence was noted in Bolivia (20.6%) and the lowest in Peru (11.0%). Predictors of HIV-1 infection varied among countries; however, a history of previous sexually transmitted disease (STD) was associated with a consistent increased risk (ORs = 1.9–2.9, AORs = 1.8–2.7). Multiple weekly sexual contacts was found to represent a secondary risk factor in Ecuador, Peru, and Argentina (ORs = 1.6–2.9, AORs = 1.6–3.1), whereas use of drugs such as cocaine was found to increase risk in Bolivia, Uruguay, and Paraguay (ORs = 2.5–6.5, AORs = 2.6–6.1). Conclusion: The results of this study illustrate an elevated HIV-1 seroprevalence among MSM participants from Andean countries. A previous STD history and multiple partners predicted HIV-1 infection in the seven countries of South America. In Southern Cone countries, HIV-1 infection was also associated with use of illegal drugs such as cocaine.

Taenia solium cysticercosis hotspots surrounding tapeworm carriers: Clustering on human seroprevalence but not on seizures

Background Neurocysticercosis accounts for 30%–50% of all late-onset epilepsy in endemic countries. We assessed the clustering patterns of Taenia solium human cysticercosis seropositivity and seizures around tapeworm carriers in seven rural communities in Peru. Methodology The presence of T. solium–specific antibodies was defined as one or more positive bands in the enzyme-linked immunoelectrotransfer blot (EITB). Neurocysticercosis-related seizures cases were diagnosed clinically and had positive neuroimaging or EITB. Principal Findings Eleven tapeworm carriers were identified by stool microscopy. The seroprevalence of human cysticercosis was 24% (196/803). Seroprevalence was 21% >50 m from a carrier and increased to 32% at 1–50 m (p = 0.047), and from that distance seroprevalence had another significant increase to 64% at the homes of carriers (p = 0.004). Seizure prevalence was 3.0% (25/837) but there were no differences between any pair of distance ranges (p = 0.629, Wald test 2 degrees of freedom). Conclusion/Significance We observed a significant human cysticercosis seroprevalence gradient surrounding current tapeworm carriers, although cysticercosis-related seizures did not cluster around carriers. Due to differences in the timing of the two outcomes, seroprevalence may reflect recent T. solium exposure more accurately than seizure frequency.

Seroprevalence of and risk factors for HIV-1 infection among female commercial sex workers in South America

Objective: Assessment of HIV prevalence and associated risk behaviours among female commercial sex workers (FCSW) across major cities in South America. Methods: Seroepidemiological, cross sectional studies of 13 600 FCSW were conducted in nine countries of South America during the years 1999–2002. Participants were recruited in brothels, massage parlours, hotels, and streets where anonymous questionnaires and blood samples were collected. HIV infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot confirmatory tests. Results: The overall HIV seroprevalence was 1.2% (range 0.0%–4.5%). The highest HIV seroprevalences were reported in Argentina (4.5%) and Paraguay (2.6%); no HIV infected FCSW were detected in Venezuela and Chile. Consistent predictors of HIV seropositivity were: (1) a previous history of sexually transmitted infections (STI, AORs = 3.8–8.3), and (2) 10 years or more in commercial sex work (AORs = 2.2–24.8). In addition, multiple (⩾3) sexual contacts (AOR = 5.0), sex with foreigners (AOR = 6.9), use of illegal drugs (AOR = 3.2), and marijuana use (AOR = 8.2) were associated with HIV seropositivity in Southern Cone countries. Conclusions: Consistently low HIV seroprevalences were detected among FCSW in South America, particularly in the Andean region. Predictors of HIV infection across the continent were STI and length of commercial sex work; however, use of illegal drugs, especially marijuana, and sexual contacts with foreigners were also found to be associated risk factors in the Southern Cone region. Interventions for the control of HIV and other STI need to be region and country specific; drug use appears to have an ever increasing role in the spread of HIV among heterosexually active populations.

Violence as a Barrier for HIV Prevention among Female Sex Workers in Argentina

Background Violence against female sex workers (FSWs) has been increasingly reported as an important determinant of HIV infection risk. This study explores the frequency of different violent experiences (sexual abuse, rejection, beating and imprisonment) among FSWs in Argentina and its association with condom use and HIV and T. pallidum prevalence. Methods A convenience sample of 1255 FSWs was included in a cross-sectional study conducted between October 2006 and November 2009. Results Sexual abuse was reported by 24.1% (219/907) of women. A total of 34.7% (42/1234) reported rejection experiences, 21.9% (267/1215) reported having been beaten and 45.4% (561/1236) stated having been arrested because of their sex work activity. There was a higher frequency of inconsistent condom use with clients among FSWs who had experienced sexual abuse, rejection, and police detention. A higher frequency of HIV and T. pallidum infection was detected among FSWs who reported having been arrested by the police. Conclusion The study shows for the first time the frequency of different violent situations among FSWs in Argentina. The association between violence against sex workers, condom use and STI prevalence demonstrated here calls for measures to reduce stigma and violence against FSWs. Such violent experiences may increase vulnerability to STI through coerced unprotected sex.

Buenos Aires cohort of men who have sex with men: prevalence, incidence, risk factors, and molecular genotyping of HIV type 1.

The prevalence, incidence, risk factors, and molecular genotyping of HIV-1 infection among men who have sex with men (MSM) were assessed through a prospective cohort study. The study was conducted in Buenos Aires from February 2003 to December 2004. Sociodemographic, sexual risk behavior data, and blood samples for HIV testing were collected at baseline and at 6 and 12 months. Cox regression analysis was applied to determine risk factors associated with HIV seroconversion. HIV-positive samples were analyzed by partial (pro/RT) and full-length genome sequencing. Of 811 HIV-negative participants evaluated at baseline, 327 volunteers that fulfilled the inclusion criteria were enrolled. Retention rates at 6 and 12 months were 97.2% and 91.5%, respectively. Twelve MSM seroconverted for HIV infection [incidence rate = 3.9 (95% CI = 2.0-6.7) per 100 person-years]. HIV seroconversion was associated with a greater number of different sexual contacts in the preceding 6 months (> or =10, hazard ratio = 3.3, 95% CI: 1.1-10.4). By partial pro/RT genotyping analysis, 83% HIV-positive samples were subtype B and 17% samples were BF recombinants, most of these being unique recombinant forms. This study describes for the first time the recruitment and follow-up of a cohort of MSM in Argentina. Retention rates and HIV incidence rate were high. These data should be considered as a promising potential population for HIV vaccine trials.

Circulating recombinant form CRF02_AG in South America.

With the objective of monitoring the distribution of HIV-1 subtypes and circulating recombinant forms (CRFs)in South America, population-based surveillance studies were performed in seven countries. Peripheral blood mononuclear cell, filter paper, fresh blood, and cocultivation samples were collected from HIV-positive patients from Colombia, Ecuador, Peru, Bolivia, Chile, Argentina, and Uruguay, during a 7-year period(1995-2001). DNA was prepared and HIV envelope subtypes were determined by heteroduplex mobility as-say and DNA sequencing from 1289 HIV-positive samples. While subtypes B and F were the most commonly observed subtypes, two CRF02_AG strains were detected, in Ecuador. This is the first report of the existence of this CRF in South America.

Epilepsy and neurocysticercosis: an incidence study in a Peruvian rural population.

Background: Epilepsy is a serious neurological disorder and neurocysticercosis (NCC), the central nervous system infection by the larvae of Taenia solium, is the main cause of acquired epilepsy in developing countries. NCC is becoming more frequent in industrialized countries due to immigration from endemic areas. Previously reported epilepsy incidences range from 30 to 50/100,000 people in industrialized countries and 90 to 122/100,000 people in developing countries. Objectives: To determine the incidence of epilepsy in a cysticercosis endemic area of Peru.Methods: A screening survey for possible seizure cases was repeated biannually in this cohort for a period of 5 years (1999–2004) using a previously validated questionnaire. All positive respondents throughout the study were examined by a trained neurologist in the field to confirm the seizure. If confirmed, they were offered treatment, serological testing, neuroimaging (CT scans and MRI) and clinical follow-up. Results: The cohort study comprised 817 individuals. The overall epilepsy incidence rate was 162.3/100,000 person-years, and for epileptic seizures, 216.6/100,000 person-years. Out of the 8 individuals who had epileptic seizures, 4 had markers for NCC (neuroimaging and/or serology). Conclusion: The incidence of epilepsy in this area endemic for cysticercosis is one of the highest reported worldwide.