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At least 19 recordsLinked to original sources
PubMed2006

Linking HIV and antiretroviral drug resistance surveillance in Peru: a model for a third-generation HIV sentinel surveillance.

BACKGROUND: HIV drug resistance surveillance is limited by recruitment and selection bias and by limited information regarding HIV incidence rates, secondary resistance, and treatment prevalence. METHODS: A second-generation HIV sentinel surveillance among men who have sex with men (MSM), regardless of prior history of HIV screening, serostatus, or treatment, was conducted in Peru in 2002. Recent HIV infection was estimated using sensitive/less sensitive enzyme immunoassay testing. Genotypic resistance testing was performed. RESULTS: HIV prevalence was 13.9% (456 HIV positive of 3280 participants). HIV incidence was estimated to be 5.1 per 100 person-years (95% confidence interval: 3.1-8.3). Among 143 MSM who were aware of their HIV infection before testing, only 20 (14.0%) were receiving antiretrovirals (ARV). Mutations conferring ARV resistance were found in 12 (3.3%) of 359 treatment-naive and 5 (31.3%) of 16 treatment-experienced participants with successful genotyping. One recently infected man from Lima demonstrated 3-class multidrug resistance. The most frequently observed mutations in treatment-naive, chronically infected persons from Lima were M184V (1.7%), D30N (1.3%), L90M (1.3%), and L10I (1.3%). CONCLUSIONS: The prevalence of ARV resistance among treatment-naive MSM in Peru is low, reflecting limited access to treatment before 2004, and contrasts with the history of ARV treatment in developed countries, where high levels of nucleoside reverse transcriptase inhibitor resistance occurred before introduction of highly active antiretroviral therapy. Linking ARV resistance and HIV sentinel surveillance in developing settings is feasible and should be considered in third-generation HIV sentinel surveillance programs.

Adult↗
PubMed2003

Demonstration of declining community prevalence of Chlamydia trachomatis infection using sentinel surveillance.

BACKGROUND: Chlamydia trachomatis infection rates in Alabama increased dramatically from 1996 to 1998, due in part to expanded screening. Detection of prevalent infection through increased testing could mask timely detection of the impact of screening programs on community prevalence. GOAL: The goal of the study was to evaluate the temporal trend in prevalence among women aged 15 to 34 years attending reproductive healthcare clinics in Birmingham, Alabama. STUDY DESIGN: Between 1995 and 1998, systematic screening of the first 60 women presenting each month to each of six participating clinics was performed with urine-based testing for chlamydia. RESULTS: In contrast to the 218% increase in chlamydia prevalence detected through passive surveillance, during the study period surveillance in sentinel sites revealed that first-visit chlamydia prevalence declined from 12.8% to 8.6%. CONCLUSIONS: Sentinel site surveillance served as a valuable adjunct to passive surveillance for determining the true trend of chlamydia prevalence during the hyperendemic phase of a local epidemic.

Adolescent↗
PubMed1993

Sentinel surveillance for HIV-1 among pregnant women in a developing country: 3 years' experience and comparison with a population serosurvey.

OBJECTIVES: To establish unlinked, anonymous sentinel surveillance for HIV-1 among pregnant women attending an antenatal clinic, to determine age-specific seroprevalences, to monitor trends and to compare seroprevalence with that detected by a population serosurvey. To establish the sustainability and costs of surveillance. DESIGN: Sentinel surveillance for HIV through serial collection of unlinked, anonymous seroprevalence data from antenatal care; comparison of sentinel data with those from a population serosurvey; financial and general audit of the sentinel surveillance. SETTING: A community antenatal clinic in a large urban centre, Mwanza Municipality, Tanzania, eastern Africa, between October 1988 and September 1991. PATIENTS: Pregnant women attending for antenatal care. MAIN OUTCOME MEASURE: Age-specific HIV-1 seroprevalences, trends over time, difference from age-specific population seroprevalences, sustainability and costs. RESULTS: Overall HIV-1 seroprevalence was 11.5% (95% confidence interval, 10.5-12.4); differences in age-specific prevalences were not significant. There was no clear evidence of change in seroprevalence over the study period in any age group, although there was some indication of a rise in some age groups in 1988-1989. Sentinel surveillance among pregnant women may have significantly underestimated population HIV-1 seroprevalence for women under the age of 35 years. HIV-1 surveillance proved feasible and sustainable. Additional recurrent costs were US$1.7 per specimen for unlinked anonymous testing and US$0.57 per woman for syphilis screening. CONCLUSIONS: HIV-1 seroprevalence did not change significantly over 3 years, probably implying a substantial incidence of HIV-1 infection. In this setting seroprevalence in pregnant women may have underestimated population seroprevalence in women aged under 35 years. With modest inputs and good organization unlinked anonymous HIV-1 sentinel surveillance of pregnant women can be introduced and sustained in an African setting. This may usefully be carried out in conjunction with syphilis screening.

AIDS Serodiagnosis↗
PubMed2002

Monitoring HIV through sentinel surveillance in Morocco.

HIV sentinel surveillance was performed in five provinces of Morocco in 1993, expanded to 10 provinces in 1996. The activity was done by unlinked anonymous testing procedures. We analysed the data from 1993 to 1999. The groups studied were sexually transmitted infections, clinic attendees, pregnant women and patients with pulmonary tuberculosis. The results show that overall HIV prevalence rate over the whole period in 10 cities was 0.10% (45/44,233). Casablanca had a significantly high rate with 0.39% (10/2567). The patients with pulmonary tuberculosis displayed the highest prevalence with 0.36% (9/2530). These data confirm the assumption that the HIV epidemic is low in Morocco. However, the increase of HIV prevalence lately calls for reinforcing preventive measures to limit its spread.

AIDS Serodiagnosis↗
PubMed1995

Influenza surveillance: experiences from establishing a sentinel surveillance system in Germany.

OBJECTIVES: Before and during peak influenza periods there is increased morbidity from other respiratory tract disorders. Sentinel networks of primary care physicians can be very effective in the early detection of influenza epidemics and the German network, the Arbeitsgemeinschaft Influenza (AGI), began its work in this area in 1992. METHODS: Data are transmitted weekly from the doctor's computer via Btx to a central computer. The numerator is the weekly number of acute respiratory infections (ARI) in five age groups and the denominator is the weekly number of patient consultations. Data on hospitalisation, mortality, and days of sick leave from work or school are also collected. Swabs for influenza specimens are collected in 30 physicians' offices each Monday and sent to three reference centres. FINDINGS: During the last recording period, from week 46 1993 to week 15 1994, 411 physicians' offices participated in the network. For 16 to 22 weeks, more than 60% of the participants transmitted data. During both the 1992-93 and 1993-94 influenza seasons, peaks were observed in the rate of ARI. There was a corresponding increase in sick leave from work and school. Rates for hospitalisation and deaths due to influenza showed no peaks during either season. CONCLUSIONS: Although the German sentinel network for influenza experienced some technical problems in the first year, it was possible to solve these. Reporting rates were very satisfactory in the second year. The network will now be expanded to include 750 physicians in order to receive 600 weekly reports and obtain a solid baseline for an early warning system.

Adolescent↗
PubMed2004

[Relevance of sentinel surveillance systems for the implementation and evaluation of vaccination strategies].

In sentinel surveillance a prearranged sample of reporting sources-often healthcare providers-agrees to report all cases of defined conditions. The German "Protection Against Infection Act" (IfSG) provides a mandate to the Robert Koch-Institute (RKI) to establish sentinel surveillance of not notifiable diseases relevant to public health. Sentinel systems with RKI involvement include two networks of private practitioners reporting cases of influenza and measles (within the Working Groups on Influenza and Measles, respectively). In addition a laboratory-based sentinel system reports cases of certain bacterial infections in children. Results from these systems serve as a basis for framing vaccination recommendations and goals as well as for the evaluation, adjustment and promotion of vaccination strategies. The data indicate time trends (e. g. number of cases by season, age and region) and supply specific information (e. g. for determination of risk factors, distribution of pathogens). Methodological problems of sentinel surveys (e. g. selection of appropriate samples, population-based estimates) can be accounted for with appropriate methods of analysis. More effective implementation of sentinel surveillance in Germany could be achieved through better coordination of existing structures. This would make more effective use of limited resources and better enable timely and flexible investigation of conceptual and organisational questions.

Adult↗
PubMed1996

Sentinel surveillance and cross sectional survey on HIV infection prevalence: a comparative study.

Despite widespread use of sentinel surveillance systems in monitoring the magnitude of HIV-1 infection in populations, little is known of how the trends they produce compare with those of the larger populations which they support to represent. The objective of this study, therefore, was to assess how useful sentinel surveillance data on HIV-1 infection might be in estimating the magnitude of HIV-1 infection in the general population. To achieve this, results from a population based study on HIV-1 infection in Bukoba town were compared with those from antenatal mothers and blood donors, all from the same town. The studies were done during the period of 1987-90. The overall HIV-1 prevalence was highest in the general population sample at 24.2% (95% CI 20.6-27.8) followed by that in antenatal mothers at 22.4% (95% CI 20.6-25.2) and lowest in blood donors at 11.9% (95% CI 9.1-15.3). Seroprevalence among antenatal clinic attenders was significantly lower than that of females from the general population sample (p = 0.016). Prevalence among female blood donors did not differ significantly from that of females from the general population sample (p = 0.06). Blood donor males had a lower HIV-1 seroprevalence when compared to that from the general population males (p = 0.038). The age group 25-34 years had the highest prevalence of HIV-1 infection in all the three populations indicating that this group is at the highest risk of HIV infection and that the three populations show a similar trend of age specific prevalence. From these findings, it is noted that female blood donors as a sentinel population represents more closely estimates of HIV-1 seroprevalence of females in the general population than antenatal clinic attenders or male blood donors. Further studies are proposed in different settings in order to come up with guidelines on the methodology of using sentinel surveillance populations in monitoring HIV-1 infection.

Adolescent↗
PubMed1993

Sentinel surveillance for HIV-2 infection in high-risk US populations.

OBJECTIVES: We conducted sentinel surveillance in persons practicing behaviors known to transmit retroviruses to determine the US presence and extent of human immunodeficiency virus type 2 (HIV-2). METHODS: Sentinel surveillance for HIV-2 was conducted by testing 31,533 anonymous blood specimens from patients at sexually transmitted disease clinics, injecting drug users at treatment centers, and clients at HIV counseling and testing sites in 14 US cities where West African immigrants often settle. Specimens were tested by HIV-1 and HIV-2 whole virus and synthetic peptide enzyme immunoassay and confirmed by HIV-1 and HIV-2 Western blots. RESULTS: Nearly 10% of 31,533 sera were positive for HIV-1. Two heterosexual Black male sexually transmitted disease patients were infected with HIV-2. One of the HIV-2 positive specimens did not cross-react on HIV-1 enzyme immunoassay screening. One client had antibodies consistent with malarial infection in West Africa; the other, who had syphilis, did not have antibodies to malaria or to any of 20 arboviruses present in Africa. CONCLUSIONS: Clinics serving clients from HIV-2 endemic areas should test persons practicing risk behaviors for both HIV-1 and HIV-2. Sentinel surveillance for HIV-2 serves as an early warning system for the possible spread of this virus in the United States.

Adult↗
PubMed2000

Incidence of amantadine-resistant influenza A viruses in sentinel surveillance sites and nursing homes in Niigata, Japan.

We surveyed the incidence of amantadine-resistant influenza A viruses both at sentinel surveillance sites and at nursing homes, and verified their types of change by partial nucleotide sequence analysis of the M2 protein. Fifty-five influenza A viruses from 27 sentinel surveillance sites during six influenza seasons from 1993 to 1999, and 26 influenza A viruses from 5 nursing homes from 1996 to 1999 were examined for susceptibility to the drug by virus titration in the presence or absence of amantadine. While amantadine-resistant viruses were not found in sentinel surveillance sites, a high frequency of resistance (8/26, 30.8%) in nursing homes was observed. Resistant viruses can occur quickly and be transmitted when used in an outbreak situation at nursing homes, where amantadine is used either for neurologic indications or for influenza treatment. Eight resistant viruses had a single amino acid change of the M2 protein at residue 30 or 31. In vitro, all 11 sensitive viruses turned resistant after 3 or 5 passages in the presence of 2 microg/ml amantadine, and they showed an amino acid change at residue 27, 30, or 31. The predominant amino acid substitution in the M2 protein of resistant viruses is Ser-31-Asp (a change at 31, serine to asparagine). The results indicate that a monitoring system for amantadine-resistant influenza viruses should be established without delay in Japan.

Amantadine↗
PubMed2002

Evaluation of a sentinel surveillance system for influenza, 1995-2000, Kyoto City, Japan.

We compared a municipal sentinel surveillance system for influenza with the Microbial Isolation Surveillance System (MISS) in Kyoto City, Japan. Sensitivity, specificity, and predictive value positive (PVP) of the Influenza Sentinel Surveillance System (ISSS) compared to the MISS were calculated by influenza season and by month. Sensitivity ranged from 80 to 97%, specificity ranged from 55 to 77%, and PVP ranged from 29 to 52% by season (P < 0.001). On the other hand, sensitivity ranged from 86 to 100%, specificity ranged from 38 to 66%, and PVP ranged from 31 to 50% by month (P < 0.001). Specificity was calculated as 93% in November. The sensitivity of ISSS was found to be sufficient regardless of the magnitude of influenza activity. Specificity varied by season, indicating the difficulty of clinically diagnosing other respiratory illnesses. The PVP remained at less than 50% before and after the influenza seasons and it varied year by year. In general, the ISSS is a good surveillance system for monitoring influenza activity.

Disease Outbreaks↗
PubMed1996

[Evaluation of the Ivory Coast sentinel surveillance system for antimalarial drug sensitivity].

This study was performed to assess the sentinel surveillance system on malaria resistance in Cote d'Ivoire using a new method. Evaluation was based on documentation describing routine products and on activity reports obtained from the surveillance system. A qualitative approach was used to assess system design and quantitative approach to assess its operation. Degree of satisfaction with evaluation criteria was scored on a scale of 1 to 5. Score reproducibility in this study was good. Overall the system was considered as satisfactory. The strong points of the system are relevance, functions, sustainability, and data quality. The weak points are poor planning, overcentralization, and underuse of information. Correction of these weakness will require concentration by all parties at the national level involved in the surveillance system. The evaluation method used was simple, cheap and reproducible and thus could serve as an alternative approach for evaluation of sentinel surveillance systems in areas with scarce resources.

Antimalarials↗
PubMed2003

Empirical modelling of population sampling: lessons for designing sentinel surveillance.

BACKGROUND: In order to consider the practical viability of 1% sentinel area surveillance for health information in resource-poor settings where complete registration is unrealistic, the effects of different sampling procedures on the representativeness of 1% population samples have been investigated. METHODS: Using the 1991 census of England as a basis for modelling, 20 1% samples, each incorporating seven key parameters, were drawn at random from the overall dataset by each of eight different sampling procedures. Each sample was compared with the 'gold standard' of the overall census results, enabling comparisons between the different sampling procedures. RESULTS: Representativeness of the 1% samples varied considerably between parameters and sampling procedures. At one extreme, the proportion of males in the population was distributed such that different sampling methods had little effect. On the other hand, samples of a heterogeneous parameter such as the proportion of non-whites in the population depended greatly on the procedure used. Sampling smaller administrative units tended to be more accurate. However, sampling units using probability proportional to size generally gave less representative samples. Stratifying urban and rural populations in the samples had little effect. Multistage sampling, emulating typical demographic surveillance sites, also generally gave less representative samples. CONCLUSIONS: It is possible to achieve representative data by taking 1% of a national population in a sentinel surveillance approach, but sampling design can have an important influence on the outcome. This modelling supports the concept of 1% sentinel surveillance for health information in poorer settings, where complete data are unavailable.

Censuses↗
PubMed1999

[Sentinel surveillance of diarrhea in Ksar-Hellal (Tunisia)].

BACKGROUND: In order to simplify the national data collection related to diarrhea, a sentinel surveillance system was implemented in the Ksar-Hellal district (Tunisia). POPULATION AND METHODS: This system was based on 461 cases of diarrhea collected from health centers and hospitals between June 1994 and December 1995. RESULTS: The collected information confirmed the previous data provided by the national system: frequency of diarrhea in health centers (4.14%), occurrence of the disease especially in the summer period, rate of hospitalization (10%) and low proportion of severe dehydration. The system also gave some new information related to the proportion of persistent diarrhea (7.1%), the low frequency of malnutrition (11%) and the etiology. CONCLUSION: The sentinel surveillance system validates information previously provided by the National Surveillance System. It also gave new information not obtained by the classical surveillance system.

Acute Disease↗
PubMed1998

Studying dynamics of the HIV epidemic: population-based data compared with sentinel surveillance in Zambia.

OBJECTIVES: To establish population-based HIV survey data in selected populations, and to assess the validity of extrapolation from HIV sentinel surveillance amongst antenatal clinic attenders (ANC) to the general population. METHODS: In a population survey, adults aged > or = 15 years were selected by stratified random cluster sampling (n = 4195). The survey was carried out in catchment populations of clinics used for national HIV surveillance. The methodology allows detailed comparisons of HIV infection patterns to be made in two areas (urban and rural). Whereas the sentinel surveillance used serum-based HIV testing, the population survey used saliva (93.5% consented to provide a saliva sample). RESULTS: Surveillance of ANC tended to underestimate the overall HIV prevalence of the general population, but differences were not statistically significant. In the urban area, the adjusted overall HIV prevalence rate of ANC (aged 15-39 years) was 24.4% [95% confidence interval (CI), 20.9-28.0] compared with 26.0% (95% CI, 23.4-28.6) in the general population. The respective rural estimates were 12.5% (95% CI, 9.3-15.6) versus 16.4% (95% CI, 12.1-20.6). Age-specific prevalence rates showed ANC to overestimate infection in teenagers (aged 15-19 years), whereas in the reverse direction of those aged > or = 30 years. Teenagers analysed by single year of age revealed both ANC and women in the general population with about the same steep increase in prevalence by age, but the former at consistently higher rates. Extrapolations might be biased substantially due to the higher pregnancy rates amongst uninfected individuals. CONCLUSIONS: ANC-based data might draw a rather distorted picture of current dynamics of the HIV epidemic. Even though representing an obvious oversimplification, extrapolations of overall prevalence rates may correlate with that of the general population.

AIDS Serodiagnosis↗
PubMed2005

Trends of HIV-1 seroincidence among HIV-1 sentinel surveillance groups in Cambodia, 1999-2002.

This study reports trends in HIV-1 incidence in Cambodia among different target groups in the HIV-1 Sentinel Surveillance Program in 1999, 2000, and 2002, using the newly developed IgG capture BED-enzyme (HIV subtypes B, E and D) immunoassay (BED-CEIA). HIV-1-positive specimens (n=3599) from 4 sentinel groups in the HIV-1 Sentinel Surveillance Program from 1999 to 2002-brothel-based commercial sex workers (CSWs), indirect commercial sex workers (IDSWs), police, and women attending antenatal clinics (ANCs)-were tested using the BED-CEIA. Annualized incidence rates were calculated for each group and each geographic region. Between 1999 and 2002, incidence rates declined among CSWs from 13.9% to 6.45%, among IDSWs from 5.92% to 2.87%, and among police from 1.58% to 0.26%. In the ANC group, the incidence remained stable, 0.64% in 1999, 1.11% in 2000, and 0.59% in 2002. However, there was an increasing trend among ANCs in rural areas, from 0.12 to 0.89%. In conclusion, HIV-1 incidence among CSWs, IDSWs, and police has declined between 1999 and 2002; however, the incidence has not declined in the ANC group.

Adolescent↗
PubMed2006

Using sentinel surveillance to monitor effectiveness of influenza vaccine is feasible: a pilot study in Denmark.

The influenza vaccine for the season 2003/04 did not contain the circulating A(H3N2)/Fujian virus strain. Vaccine effectiveness (VE) estimates were needed but unavailable. We explored whether or not laboratory based influenza surveillance can be used to estimate VE. We carried out a case-control study nested within Danish sentinel surveillance. A case was defined as a person aged 25 or above with A(H3N2)/Fujian/411/02 influenza. Four controls per case, matched on age groups and time, were selected from clients of sentinel practitioners (SP) who reported cases. SPs collected the following data in structured one-page questionnaires: vaccination status, chronic illness and previous pneumococcal vaccination. We sent postal survey questionnaires to participating SPs to assess acceptability and simplicity of data collection. Twenty four cases were identified. Data from 19 case-control sets were analysed. One control was excluded because information on vaccination status was missing. Two of the 19 cases and 11 of 75 controls had been vaccinated against influenza. The VE adjusted for chronic illness was 33% (95% CI 0%-88%) and 37% (95% CI 0%-89%) when excluding 5 controls with influenza-like illness. Twenty two SPs returned survey questionnaires. Fifteen of 17 SPs reported that it was easy to find controls. SPs collected data through interviews and clinical notes, spending 1 to 5 minutes per case and 5 to 15 minutes for all four controls. Nineteen of 22 SPs considered the amount of time they spent on the study to be acceptable, 17 said that they would like to participate again, and none ruled out further participation. Monitoring VE within sentinel surveillance systems is feasible. The small numbers in our study limit interpretation of VE. Expansion to a European multicountry study could overcome this limitation and provide VE estimates earlier in the season, for different age groups and emerging virus strains, including new and pandemic subtypes.

Adult↗
PubMed2003

Annual incidence rate of infectious diseases estimated from sentinel surveillance data in Japan.

BACKGROUND: The estimation of incidence rates of infectious diseases based on the sentinel surveillance data is rather rare. We attempted to estimate these in 2000 in Japan by the surveillance data, and to evaluate their biases. METHODS: We used the incidences of influenza-like illness and 12 pediatric diseases in each of the sentinel medical institutions in Japan based on surveillance data in 2000. The incidence in all medical institutions was estimated under the assumption that the sentinel medical institutions were randomly selected. The possible bias of this estimate was evaluated in comparison with the hypothetical true incidence obtained as the total incidence in all medical institutions estimated by a regression model using the numbers of all disease outpatients per day from the National Survey of Medical Care Institutions of Japan. RESULTS: The estimated annual incidence rate was 75.6 (95% confidence interval: 72.3-78.7) per 1,000 population in influenza-like illness, and ranged from 1.1 (95% confidence interval: 1.0-1.2) to 285.2 (95% confidence interval: 270.2-300.3) per 1,000 population aged 0-19 years among 12 pediatric diseases. The ratio of the estimated incidence to the hypothetical true one was 1.06-1.26 among influenza-like illness and the 12 pediatric diseases. CONCLUSIONS: The incidence rates of influenza-like illness and pediatric diseases in 2000 in Japan were estimated from sentinel surveillance data. The rates obtained provide some useful but not always accurate information. Thus, further research is necessary.

Adolescent↗