Willi McFarland
University of California, San Francisco
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Featured researches published by Willi McFarland.
PLOS ONE | 2010
Moupali Das; Priscilla Lee Chu; Glenn-Milo Santos; Susan Scheer; Eric Vittinghoff; Willi McFarland; Grant Colfax
Background At the individual level, higher HIV viral load predicts sexual transmission risk. We evaluated San Franciscos community viral load (CVL) as a population level marker of HIV transmission risk. We hypothesized that the decrease in CVL in San Francisco from 2004–2008, corresponding with increased rates of HIV testing, antiretroviral therapy (ART) coverage and effectiveness, and population-level virologic suppression, would be associated with a reduction in new HIV infections. Methodology/Principal Findings We used San Franciscos HIV/AIDS surveillance system to examine the trends in CVL. Mean CVL was calculated as the mean of the most recent viral load of all reported HIV-positive individuals in a particular community. Total CVL was defined as the sum of the most recent viral loads of all HIV-positive individuals in a particular community. We used Poisson models with robust standard errors to assess the relationships between the mean and total CVL and the primary outcome: annual numbers of newly diagnosed HIV cases. Both mean and total CVL decreased from 2004–2008 and were accompanied by decreases in new HIV diagnoses from 798 (2004) to 434 (2008). The mean (p = 0.003) and total CVL (p = 0.002) were significantly associated with new HIV cases from 2004–2008. Conclusions/Significance Reductions in CVL are associated with decreased HIV infections. Results suggest that wide-scale ART could reduce HIV transmission at the population level. Because CVL is temporally upstream of new HIV infections, jurisdictions should consider adding CVL to routine HIV surveillance to track the epidemic, allocate resources, and to evaluate the effectiveness of HIV prevention and treatment efforts.
Journal of Acquired Immune Deficiency Syndromes | 2007
Xiaoyan Ma; Qiyun Zhang; Xiong He; Weidong Sun; Hai Yue; Sanny Chen; H. Fisher Raymond; Yang Li; Min Xu; Hui Du; Willi McFarland
Background:Studies tracking trends in HIV prevalence and risk behavior among men who have sex with men (MSM) in China are rare. We report on 3 consecutive cross-sectional surveys measuring the prevalence of HIV, other infectious diseases, and related risk behavior among MSM in Beijing in 2004, 2005, and 2006. Methods:We applied respondent-driven sampling (RDS) to recruit MSM for a structured face-to-face interview on demographic characteristics and HIV risk-related behavior. Blood specimens were drawn for HIV, syphilis, hepatitis B virus, and hepatitis C virus (HCV) testing. Results:A total of 325 MSM participated in 2004, 427 in 2005, and 540 in 2006. HIV prevalence was 0.4% (95% confidence interval [CI]: 0.1 to 0.8) in 2004, 4.6% (95% CI: 2.2 to 7.6) in 2005, and 5.8% (95% CI: 3.4 to 8.5) in 2006. This apparent rise was accompanied by an increase in syphilis and self-reported history of sexually transmitted diseases (STDs), high prevalence of multiple sex partners, and low consistent condom use. HCV prevalence also increased, from 0.4% (95% CI: 0.1 to 0.8) in 2004 to 5.2% (95% CI: 2.3 to 8.2) in 2006. Conclusions:We detected a possible rising prevalence of HIV and related risk behavior among MSM in Beijing using RDS in each of 3 consecutive years. Practical measures, including MSM-friendly HIV testing, STD services, and health provider education, are urgently needed to stop the further spread of HIV in this population.
Aids and Behavior | 2008
Carl Kendall; Ligia Regina Franco Sansigolo Kerr; Rogério Costa Gondim; Guilherme Loureiro Werneck; Raimunda Hermelinda Maia Macena; Marta Kerr Pontes; Lisa G. Johnston; Keith Sabin; Willi McFarland
Obtaining samples of populations at risk for HIV challenges surveillance, prevention planning, and evaluation. Methods used include snowball sampling, time location sampling (TLS), and respondent-driven sampling (RDS). Few studies have made side-by-side comparisons to assess their relative advantages. We compared snowball, TLS, and RDS surveys of men who have sex with men (MSM) in Forteleza, Brazil, with a focus on the socio-economic status (SES) and risk behaviors of the samples to each other, to known AIDS cases and to the general population. RDS produced a sample with wider inclusion of lower SES than snowball sampling or TLS—a finding of health significance given the majority of AIDS cases reported among MSM in the state were low SES. RDS also achieved the sample size faster and at lower cost. For reasons of inclusion and cost-efficiency, RDS is the sampling methodology of choice for HIV surveillance of MSM in Fortaleza.
Aids and Behavior | 2009
H. Fisher Raymond; Willi McFarland
We conducted a cross-sectional survey of MSM using a time-location-sampling design in San Francisco during 2007–2008. The investigation focused on the selection of sexual partners, partner preferences, perceptions of HIV risk, and social mixing with respect to race/ethnicity. The sample of 1,142 MSM was 56% White, 22% Latino, 14% Asian, and 9% Black and reported on 3,532 sexual partnerships. Black MSM had a significant, three-fold higher level of same race sexual partnering than would be expected by chance alone (i.e., in the absence of selective forces with respect to race among partners). Black MSM were reported as the least preferred as sexual partners, believed at higher risk for HIV, counted less often among friends, were considered hardest to meet, and perceived as less welcome at the common venues that cater to gay men in San Francisco by other MSM. Our findings support the hypothesis that the sexual networks of Black MSM, constrained by the preferences and attitudes of non-Blacks and the social environment, are pushed to be more highly interconnected than other groups with the potential consequence of more rapid spread of HIV and a higher sustained prevalence of infection. The racial disparity in HIV observed for more than a decade will not disappear until the challenges posed by a legacy of racism towards Blacks in the US are addressed.
AIDS | 2005
Sally Blower; Erin N. Bodine; James G. Kahn; Willi McFarland
The U.S. Government has pledged to spend
Journal of Acquired Immune Deficiency Syndromes | 2001
Andrea A. Kim; Charlotte K. Kent; Willi McFarland; Jeffrey D. Klausner
15 billion in Africa and the Caribbean on AIDS. A central focus of this plan is to provide antiretroviral treatment (ART) to millions. Here, we evaluate whether the plan to rollout ART in Africa is likely to generate an epidemic of drug-resistant strains of HIV. We review what has occurred as a result of high usage of ART in developed countries in terms of changes in risky behavior, and the emergence and transmission of drug-resistant HIV. We also review how mathematical models have been used to predict the evolution of drug-resistant HIV epidemics. We then show how models can be used to predict the likely impact of the ART rollout on the evolution of drug-resistant HIV in Africa. At currently planned levels of treatment coverage, we predict that (over the next decade) in Africa: (i) the impact of ART on reducing HIV transmission (and prevalence) is likely to be undetectable (unless accompanied by substantial changes in behavior), (ii) the transmission rate of drug-resistant HIV will be below the WHO surveillance threshold of 5%, and (ii) the majority of cases of drug-resistant HIV that will occur will be due to acquired (and not transmitted) resistance. For the next decade, large-scale surveillance for detecting transmitted resistance in Africa is unnecessary. Instead, we recommend that patients should be closely monitored for acquired resistance, and sentinel surveillance (in a few urban centers) should be used to monitor transmitted resistance.
PLOS Medicine | 2006
Sheri D. Weiser; Karen Leiter; Michele Heisler; Willi McFarland; Fiona Percy-de Korte; Sonya DeMonner; Sheila Tlou; Nthabiseng Phaladze; Vincent Iacopino; David R. Bangsberg
&NA; This study evaluated differences in sexual behavior and risk for sexually transmitted diseases (STDs) among men who have sex with men (MSM) who met their partners on‐line and those who did not. A self‐administered questionnaire on sexual behavior was offered to a convenience sample of patients seeking public STD services. Thirty‐two percent of MSM patients reported meeting a sexual partner over the Internet in the past year. MSM with on‐line partners were younger, more likely to report sex with an HIV‐positive person in the last year, and more likely to report casual partners in the last year compared with MSM with only off‐line partners. HIV‐negative MSM with on‐line partners were more likely than HIV‐negative MSM with only off‐line partners to have received money or drugs for sex in the past year and to report sex with an HIV‐positive partner in the past year. Although meeting partners on the Internet was common and associated with increased risk for STDs in MSM, it also presents new untapped opportunities for on‐line health promotion and disease prevention.
AIDS | 2005
Kate Buchacz; Willi McFarland; Timothy A. Kellogg; Lisa Loeb; Scott D. Holmberg; James W. Dilley; Jeffrey D. Klausner
Background In Botswana, an estimated 24% of adults ages 15–49 years are infected with HIV. While alcohol use is strongly associated with HIV infection in Africa, few population-based studies have characterized the association of alcohol use with specific high-risk sexual behaviors. Methods and Findings We conducted a cross-sectional, population-based study of 1,268 adults from five districts in Botswana using a stratified two-stage probability sample design. Multivariate logistic regression was used to assess correlates of heavy alcohol consumption (>14 drinks/week for women, and >21 drinks/week for men) as a dependent variable. We also assessed gender-specific associations between alcohol use as a primary independent variable (categorized as none, moderate, problem and heavy drinking) and several risky sex outcomes including: (a) having unprotected sex with a nonmonogamous partner; (b) having multiple sexual partners; and (c) paying for or selling sex in exchange for money or other resources. Criteria for heavy drinking were met by 31% of men and 17% of women. Adjusted correlates of heavy alcohol use included male gender, intergenerational relationships (age gap ≥10 y), higher education, and living with a sexual partner. Among men, heavy alcohol use was associated with higher odds of all risky sex outcomes examined, including unprotected sex (AOR = 3.48; 95% confidence interval [CI], 1.65 to 7.32), multiple partners (AOR = 3.08; 95% CI, 1.95 to 4.87), and paying for sex (AOR = 3.65; 95% CI, 2.58 to 12.37). Similarly, among women, heavy alcohol consumption was associated with higher odds of unprotected sex (AOR = 3.28; 95% CI, 1.71 to 6.28), multiple partners (AOR = 3.05; 95% CI, 1.83 to 5.07), and selling sex (AOR = 8.50; 95% CI, 3.41 to 21.18). A dose-response relationship was seen between alcohol use and risky sexual behaviors, with moderate drinkers at lower risk than both problem and heavy drinkers. Conclusions Alcohol use is associated with multiple risks for HIV transmission among both men and women. The findings of this study underscore the need to integrate alcohol abuse and HIV prevention efforts in Botswana and elsewhere.
AIDS | 2007
Mark Berry; H. Fisher Raymond; Willi McFarland
We examined the association between amphetamine use and HIV incidence for 2991 men who have sex with men (MSM) who tested anonymously for HIV in San Francisco. HIV incidence among 290 amphetamine users was 6.3% per year (95% CI 1.9–10.6%), compared with 2.1% per year (95% CI 1.3–2.9%) among 2701 non-users (RR 3.0, 95% CI 1.4–6.5). HIV prevention programmes in San Francisco should include efforts to reduce amphetamine use and associated high-risk sexual behaviors.
Sexually Transmitted Diseases | 2006
David D. Celentano; Linda A. Valleroy; Frangiscos Sifakis; Duncan A. MacKellar; John B. Hylton; Hanne Thiede; Willi McFarland; Douglas Shehan; Susan Stoyanoff; Marlene LaLota; Beryl A. Koblin; Mitchell H. Katz; Lucia V. Torian
In a community-based survey in San Francisco, black men who have sex with men (MSM) had higher rates of same-race/ethnicity sexual partnerships and partners 10 or more years older compared with other MSM. Differences in sexual networks may explain why black MSM have higher HIV prevalence than other MSM despite lower levels of risk behavior.