Immunogenicity of the hepatitis A vaccine 20 years after infant immunization

To determine the duration of immunity provided by the Hepatitis A vaccination (HepA), we evaluated a cohort of participants in Alaska 20 years after being immunized as infants. At recruitment, participants received two doses of inactivated HepA vaccine on one of three schedules. We conducted hepatitis A antibody (anti-HAV) testing for participants at the 20-year time-point. Seventy-five of the original 183 participants (41%) were available for follow-up. The overall anti-HAV geometric mean concentration was 29.9 mIU/mL (95% CI 22.4 mIU/mL, 39.7 mIU/mL) and 50 participants (68%) remained seropositive (titer ≥ 20 mIU/mL). Using a fractional polynomial model, the predicted percent seropositive at 25 years was 55.3%, 49.8% at 30 years and 45.7% at 35 years, suggesting that the percent sero-positive could drop below 50% earlier than previously expected. Further research is necessary to understand if protection continues after seropositivity diminishes or if a HepA booster dose may become necessary.     

HIV seroincidence among patients at clinics for sexually transmitted diseases in nine cities in the United States

Although the numbers of newly reported diagnoses of AIDS decreased in the 1990s, it is not clear whether they reflect a decreasing number of new HIV infections. Direct measurement of HIV incidence through follow-up cohort studies is difficult and costly. We estimated HIV incidence and trends in incidence among men who have sex with men (MSM) and heterosexual men and women at clinics for sexually transmitted diseases (STDs) by using a recently developed serologic testing algorithm that requires only a single blood specimen. Cross-sectional anonymous serosurveys were conducted at 13 STD clinics in nine cities in the United States from 1991 through 1997. Before anonymous HIV testing, demographic and clinical information was abstracted. Of 129,774 specimens tested, 362 (0.28%) were from persons estimated to be recently infected. Incidence among MSM was 7.1% (95% confidence interval (CI): 4.8-10.3), 14 times higher than that among heterosexuals, which was 0.5% (CI: 0.4- 0.7). Incidence among MSM and heterosexuals remained unchanged during the time studied. Decreasing rates of new AIDS diagnoses in the 1990s do not reflect stable rates of new HIV infections among MSM and heterosexual patients attending these clinics.     

Association between crack cocaine use and high-risk sexual behaviors after HIV diagnosis

OBJECTIVE: To describe the prevalence of crack cocaine use in an HIV-infected population and to examine the association between crack use after HIV diagnosis and high-risk sexual behaviors for heterosexual men, heterosexual women, and men who have sex with men (MSM). METHODS: Analysis of cross-sectional interviews conducted from January 1995 through December 1998 with HIV infected adults in 12 states. RESULTS: Of 10,415 persons with HIV or AIDS, 66.6% never used crack, 10.7% used crack before HIV diagnosis but not after, and 22.7% used crack after diagnosis. High-risk sexual behaviors were more prevalent among those who had ever used crack and were most prevalent among those who used crack after diagnosis. In multivariable analyses, crack use after diagnosis was associated with having multiple sex partners and trading sex for drugs/money in all three groups: heterosexual men, heterosexual women, and MSM. For heterosexual women and MSM, crack use after diagnosis was associated with unprotected sex with a main partner, and among heterosexual men and MSM, with unprotected sex with casual partners. CONCLUSIONS: Crack use after HIV diagnosis was associated with high-risk sexual behaviors. Treatment programs to assist people in quitting crack are needed to help reduce the risk of HIV transmission from this population.     

实时荧光定量RT-PCR监测恒河猴体内人/猴免疫缺陷病毒载量在传代过程中的变化

目的为分析中国SHIV/猕猴AIDS模型的病毒载量变化趋势,建立一种实时、灵敏、特异的针对人/猴免疫缺陷病毒的定量检测方法。方法体外转录制备RNA标准品,利用TaqManEZRT-PCR试剂盒的反应体系和针对SHIVgag保守区91个碱基的TaqMan探针和引物,建立一步法实时荧光定量RT-PCR。提取126份来自SHIV-CN97001感染恒河猴血浆病毒RNA并定量检测。结果利用梯度稀释的RNA标准品对反应体系进行优化,标准曲线下限达到2×102拷贝/ml,相关性(r>0.99)及重复性(CV=4.14%)均能达到测定要求。病毒载量的检测结果表明SHIV-CN97001在猴体内传代过程中病毒载量有先升后降的趋势,病毒载量通常在接种病毒或感染猴的全血后第14天达到高峰。血浆载量可达到105~106拷贝/ml。结论成功地建立了一步法定量SHIVRNA的实时荧光定量RT-PCR,为SHIV/恒河猴AIDS模型的建立与应用提供了灵敏的病毒载量检测方法。SHIV-CN97001的体内繁殖能力在猴体内传代过程中有所增强。     

HIV testing within at-risk populations in the United States and the reasons for seeking or avoiding HIV testing

OBJECTIVES: We determined proportions of high-risk persons tested for HIV, the reasons for testing and not testing, and attitudes and perceptions regarding HIV testing, information that is critical for planning prevention programs. METHODS: Cross-sectional interview study of persons at high risk for HIV infection (men who have sex with men [MSM]; injection drug users [IDUs]; and heterosexual persons recruited from gay bars, street outreach, and sexually transmitted disease clinics) among six states participating in the HIV Testing Survey (HITS) in 1995 to 1996 (HITS-I) and 1998 to 1999 (HITS-II). RESULTS: Overall testing rates were lower in the HITS-I (1226/1599 [77%]) than in the HITS-II (1375/1711 [80%]) (p =.01). Persons <25 years old tested less frequently than those >or=25 years old (HITS-I: 71% vs. 78%, respectively, p=.007; HITS-II: 63% vs. 85%, respectively, p<.001). The main reasons for testing and not testing were the same in both surveys, but the proportions of reasons for not testing differed (e.g., "unlikely exposed to HIV" [HITS-I (17%) vs. HITS-II (30%), p<.0001], "afraid of finding out HIV-positive" [HITS-I (27%) vs. HITS-II (18%), p<.0001]). Attitudes regarding HIV testing differed among tested and untested respondents, especially among MSM. CONCLUSIONS: HIV testing rates were higher in the HITS-II, but testing rates decreased among the youngest respondents. Denial of HIV risk factors and fear of being HIV-positive were the principal reasons for not being tested. Availability of new HIV therapies may have contributed to decreased fear of finding out that one is HIV infected as a reason to avoid testing. The increased proportion of persons at risk who did not test because they believed they were unlikely to have been exposed highlights the need for prevention efforts to address risk perceptions.     

中国首批美沙酮维持治疗门诊病人入组情况及治疗维持率

目的：了解中国首批美沙酮维持治疗门诊病人数量变化情况并计算其治疗维持率。方法：使用美沙酮维持治疗管理系统软件收集中国首批8个美沙酮维持治疗门诊数据,并进行数据整理与分析。结果：除浙江舟山门诊、广西南宁门诊和贵州织金门诊以外,其余5个门诊的在诊病人数均在6个月以内超过100人。首批8个门诊6个月及12个月的平均维持率分别为63%和48%,其中个旧门诊6个月及12个月的治疗维持率均列8个门诊之首,分别为84%和65%。结论：中国首批8家美沙酮维持治疗试点门诊运转平稳,但仍需要提高病人治疗维持率。     

中国恒河猴(Macaca mulatta)外周血CD4+CD25+T淋巴细胞的研究

目的:研究中国恒河猴外周血中CD4 CD25 T淋巴细胞亚群及其分布频率。方法:利用流式细胞术对50只中国恒河猴外周血CD4 CD25 T淋巴细胞进行了分析。结果:发现所有被检测的恒河猴个体中均存在明显的CD4 CD25 T淋巴细胞亚群;CD4 CD25 T淋巴细胞大约占CD4 T淋巴细胞的9.1%(变化范围为2.6%～18.1%);其中CD4 CD25highT淋巴细胞约占2.5%(0.3%～5.5%)。对不同年龄和性别个体中CD4 CD25 T淋巴细胞频率的初步分析未发现统计学上有年龄或性别差异。结论:中国恒河猴可用于与CD4 CD25 T细胞相关的人类疾病的研究中。