Nepalese origin of cholera epidemic in Haiti.

Cholera appeared in Haiti in October 2010 for the first time in recorded history. The causative agent was quickly identified by the Haitian National Public Health Laboratory and the United States Centers for Disease Control and Prevention as Vibrio cholerae serogroup O1, serotype Ogawa, biotype El Tor. Since then, >500 000 government-acknowledged cholera cases and >7000 deaths have occurred, the largest cholera epidemic in the world, with the real death toll probably much higher. Questions of origin have been widely debated with some attributing the onset of the epidemic to climatic factors and others to human transmission. None of the evidence on origin supports climatic factors. Instead, recent epidemiological and molecular-genetic evidence point to the United Nations peacekeeping troops from Nepal as the source of cholera to Haiti, following their troop rotation in early October 2010. Such findings have important policy implications for shaping future international relief efforts.

A street intercept survey to assess HIV-testing attitudes and behaviors.

Nationally, it has been estimated that 44% of adults in the United States have been tested for HIV, with substantial individual and community-level variations in HIV-testing attitudes and behaviors. HIV-testing behaviors and intentions and attitudes toward HIV testing, particularly toward home tests, were assessed among 385 adults recruited in a street intercept survey from a gay-identified agency, a substance-abuse treatment program, and inner-city community venues (a shopping mall and community center). Across these Los Angeles sites, the proportion of persons reported being tested for HIV in their lifetime (77%) was higher than the national estimate. Gay-identified agency (88%) and substance-abuse treatment program participants (99%) were more likely to have been tested than were the community participants (67%). Participants from a gay-identified agency were more likely to have had an anonymous test (51%) than were those from a substance-abuse treatment program (25%) or community sites (24%). Attitudes toward HIV testing, including mail-in home-test kits and instant home tests, were very positive. Most participants were willing to pay about $20 for a home-test kit. Participants from the community sites (82%) and the substance-abuse treatment program participants (87%) endorsed notification of HIV status to health departments and sexual partners more than did participants from the gay identified agency (48%). The street intercept survey appears to be a quick and feasible method to assess HIV testing in urban areas.

Small-community-based surveys.

Rapid, small surveys are routinely done in much of the developing world but are less common in the United States. We present as an example a rapid survey of immunization status and other factors in a predominantly Hispanic region in Los Angeles. The survey united county employees, students, and community volunteers, first to enumerate the eligible population and then to conduct in-person interviews. Sampling was done in two stages in a downtown region of Los Angeles. Over the course of two weekends and during clean-up the following week, volunteers and others enumerated 718 eligible children in 30 clusters (i.e. groups of blocks). At the second stage, also in two weekends with midweek clean-up, we selected by simple random sample 10 children per cluster. The parents or legal guardians of 270 children were interviewed about vaccination issues, including home presence of an immunization card. Nearly one fourth of the respondents did not have a home telephone number and thus would have been underrepresented in a telephone survey. Information from such rapid surveys is important for local program planning and evaluation.

Immunization coverage among predominantly Hispanic children, aged 2-3 years, in central Los Angeles.

PURPOSE: To assess the immunization status of young children in a predominantly Hispanic region in and around downtown Los Angeles, and factors associated with complete immunization by age 24 months. METHODS: The information was gathered in a two-stage cluster survey with probability proportionate to estimated size (PPS) sampling of 30 clusters at the first stage, and simple random sampling of a constant number of children at the second stage. Vaccination coverage was determined by a review of the home immunization (HI) card, or of clinic records. RESULTS: Of the 270 sampled children, 91.5% were Hispanic and 6.7% were Black. Home telephone numbers were not available in 24.8% of the homes, and 34.1% reported having no health insurance. Vaccination coverage was over 90% for the first three doses of Diphtheria, tetanus toxoids and pertussis/ diphtheria, tetanus toxoids and acellular pertussis vaccine (DTP/DTaP)/Diphtheria and tetanus toxoids vaccine (DT), first two doses of poliovirus (Polio) vaccine, first dose of measles, mumps and rubella (MMR) vaccine, and first two doses of hepatitis B (Hep B) vaccine. Yet, by age 24 months, only 72.2% of the children had received the combined series of 4:3:1 (i.e., four DTP/DTaP/DT, three Polio, one MMR). This was further reduced to 64.4% for the combined series of 4:3:1:3:3 (i.e., four DTP/DTaP/ DT, three Polio, one MMR, three Haemophilus influenzae type b (Hib), three Hep B). Factors associated with completed on-time vaccination were having an HI card available during the interview and being enrolled in Supplemental Nutrition Program for Women, Infants and Children (WIC). CONCLUSIONS: While vaccination levels for individual antigens were found to be high, more emphasis needs to be placed on getting preschool children vaccinated on-time according to the Recommended Childhood Immunization Schedule.

Compliance with childhood immunizations in Kern County, California.

A rapid survey was conducted to describe the immunization status of the 0- to 2-year-old population in selected communities of Kern County, California, and identify reasons for noncompliance with immunization recommendations. Households were selected by two-stage cluster sampling. Among 860 children, 38% had received immunizations on schedule, while 44% had not received the recommended doses for their age. Compliance with the immunization schedule worsened dramatically after the first year of life. Among 2 year olds, the proportion that had the recommended number of vaccine doses was 81% for MMR, 82% for polio, 65% for DTP, and 47% for Hib. Parents' main reasons for noncompliance included child's illness, procrastination, and limited access to information and services. The low levels of compliance reflect lack of active follow-up in preventive health care across socioeconomic levels. The results show the importance of aiming immunization messages at parents and physicians of 12- to 18-month-old children. The rapid survey approach offers public health agencies an efficient means of assessing community health problems and targeting programs according to need.

Stability of saliva for measuring HIV in the tropics.

If HIV is to be detected among pregnant women in remote regions of the tropics, HIV antibodies need to remain stable until specimens arrive at the laboratory. Our objective was to assess the stability of HIV antibodies in saliva held for up to 1 month at ambient temperature in Yangon, Myanmar. We gathered 10 saliva specimens from each of 102 HIV-infected persons with the Omni-Sal collection device (Saliva Diagnostic Systems, Inc.), and for each subject, divided the saliva into 15 portions. During 33 days, the 102 saliva specimens, kept at ambient temperature, were tested every 2-3 days for HIV antibodies (total 1530 assays) with the GACELISA (Murex Diagnostics Ltd), a highly sensitive test designed for use with saliva. We observed no reduction in test performance over 33 days, indicating that the antimicrobial and antiproteolytic transport medium in the Omni-Sal device can preserve HIV antibodies without refrigeration for up to a month before saliva specimens reach the laboratory.

Local evaluation of a rapid HIV assay for use in developing countries.

We present a research scheme for evaluating inexpensive HIV rapid tests in a developing country setting and assess the field validity of the Sero Strip HIV 1/2 rapid test. The research design features the random allocation of 100 true HIV-positive and 100 true HIV-negative serum specimens to 4 groups, followed by blind testing for HIV status. After one short training session, laboratory technicians at 4 township hospitals (25-35 beds) located 20-50 km from Yangon, Myanmar were sent 800 sera labelled with only an identification number and divided into four groups of 200 specimens each, half being HIV-positive and half HIV-negative. Testing was done in the field with the Sero-Strip HIV 1/2. Determination of the test's validity was based on 399 true HIV positive and 401 true HIV negative sera. All true positives were correctly identified, as were all but two of the true negatives. The sensitivity (% of true positives that test positive) was 100%, and the specificity (% of true negatives that test negative) was 99.5%. The research was completed by in-country scientists who are best suited to evaluate the validity of HIV tests conducted in local environments.

Failure to learn human immunodeficiency virus test results in Los Angeles public sexually transmitted disease clinics.

BACKGROUND: Early human immunodeficiency virus (HIV) defection is essential for initiating treatment and partner-notification activities. Sexually transmitted disease (STD) clinic attendees are at high risk for infection and should be made aware of their HIV status. GOAL: To determine the characteristics associated with not receiving an HIV test result in an STD clinic setting. STUDY DESIGN: Confidential HIV testing was offered to 6,705 persons attending four public STD clinics in Los Angeles who submitted blood for syphilis serology and were tested for HIV antibody in an unlinked HIV serosurvey. Human immunodeficiency virus test results and return status were anonymously linked to other risk information. RESULTS: Only one-third of attendees were tested and given their results. Those testing HIV positive in the anonymous survey and those requesting HIV testing were most likely to receive a test result (i.e., 41% and 49%, respectively). Those solely requesting an STD examination, repeat testers, and African-Americans were least likely to receive a result (i.e., 32%, 30%, and 26%, respectively). CONCLUSIONS: Most STD clinic patients fail to receive an HIV test result. Other strategies, such as rapid HIV testing, are needed to increase participation and receipt of HIV test results in this high-risk population.

Secondary HIV prevention.

AIDS: Primary HIV prevention, preventing HIV exposure among uninfected persons, has been the focus of much attention. However, secondary HIV prevention, preventing HIV transmission from infected people to their uninfected contacts, has not received as much interest or attention from HIV researchers, clinicians, and policymakers. The concept of secondary HIV prevention, as distinguished from primary prevention, is clarified, and the current and future strategies to further secondary HIV prevention efforts are explored. Secondary prevention strategies can be incorporated into comprehensive programs and result in shifts in attitudes and behaviors. This could reduce the size of the epidemic, while also benefiting the individual and his or her close relationships.^ieng

Minimum attack rate for measuring measles vaccine efficacy.

BACKGROUND: For evaluating measles vaccine efficacy (VE) in the field, some investigators have suggested that an overall attack rate level of 5% or more in a randomly mixing population is sufficient to provide equal exposure to the viral agent in both vaccinated and unvaccinated groups. It is not clear, however, if this assumption is valid given the effect of herd immunity. METHODS: We created a computer simulation model based on the stochastic extension of the Reed-Frost model and tested for variation in bias in VE estimation due to herd immunity, based on runs of 200 trials. RESULTS: At higher levels of attack rate, the degree of herd immunity decreases, as does the percentage of trials with bias in VE estimation. The two main factors that affect the level of attack rate are the probability of adequate contact and the number of susceptibles. At a given level of attack rate, the number of susceptibles is positively associated with the percentage of biased trials in VE estimation. Since vaccination reduces the number of susceptibles, we also observe that when controlling for attack rate, higher vaccination coverage results in lower bias in VE estimation. CONCLUSION: The results show that the assumption of no bias when the attack rate is 5% or more becomes increasingly true when a large percentage of a randomly mixing population is immune.

Saliva-based HIV-antibody testing in Thailand.

OBJECTIVE: To determine whether saliva could serve as an alternative to serum for HIV-antibody testing in an ongoing sentinel surveillance program in Thailand. METHODS: Serum and saliva specimens were collected from 1955 individuals in four of the 73 sentinel sites of the national surveillance program in Thailand. Intravenous drug users, female prostitutes, and men attending sexually transmitted disease clinics were included as participants. All specimens were collected and tested anonymously. Saliva was gathered with the Omni-Sal collection device and analyzed for the presence of HIV antibodies using the immunoglobulin G antibody-capture enzyme-linked immunosorbent assay (GACELISA) laboratory test, specially designed for low concentration body fluids. Our gold standard was serum, collected and analyzed independently from the saliva specimens, using an ELISA test for screening and Western blot for confirmation. Linkage between serum and saliva was blind to the laboratory. A set of HIV-positive and HIV-negative quality assurance samples for both serum and saliva were also analyzed blind. RESULTS: Findings are presented as observed in the field, and as quality assurance samples after the correction of various field and laboratory errors. The sensitivity of the GACELISA with saliva was 98.0% in the field (298 HIV-positive specimens), 100% after correction of errors (300 HIV-positive specimens), and 100% among the quality assurance samples (95 HIV-positive specimens). The specificity of the GACELISA was 99.4% in the field (1653 HIV-negative specimens), 99.6% after correction of errors (1654 HIV-negative specimens), and 100% among the quality assurance samples (96 HIV-negative specimens). CONCLUSION: Our findings support other published studies that also featured the GACELISA. We conclude that saliva is comparable to serum for assessing HIV antibodies in individuals for surveillance and screening purposes.