Clinic-based Surveillance Research Articles

Lyme Disease Under-Ascertainment During the COVID-19 Pandemic in the United States: Retrospective Study.

The COVID-19 pandemic resulted in a massive disruption in access to care and thus passive, hospital- and clinic-based surveillance programs. In 2020, the reported cases of Lyme disease were the lowest both across the United States and North Carolina in recent years. During this period, human contact patterns began to shift with higher rates of greenspace utilization and outdoor activities, putting more people into contact with potential vectors and associated vector-borne diseases. Lyme disease reporting relies on passive surveillance systems, which were likely disrupted by changes in health care-seeking behavior during the pandemic. This study aimed to quantify the likely under-ascertainment of cases of Lyme disease during the COVID-19 pandemic in the United States and North Carolina. We fitted publicly available, reported Lyme disease cases for both the United States and North Carolina prior to the year 2020 to predict the number of anticipated Lyme disease cases in the absence of the pandemic using a Bayesian modeling approach. We then compared the ratio of reported cases divided by the predicted cases to quantify the number of likely under-ascertained cases. We then fitted geospatial models to further quantify the spatial distribution of the likely under-ascertained cases and characterize spatial dynamics at local scales. Reported cases of Lyme Disease were lower in 2020 in both the United States and North Carolina than prior years. Our findings suggest that roughly 14,200 cases may have gone undetected given historical trends prior to the pandemic. Furthermore, we estimate that only 40% to 80% of Lyme diseases cases were detected in North Carolina between August 2020 and February 2021, the peak months of the COVID-19 pandemic in both the United States and North Carolina, with prior ascertainment rates returning to normal levels after this period. Our models suggest both strong temporal effects with higher numbers of cases reported in the summer months as well as strong geographic effects. Ascertainment rates of Lyme disease were highly variable during the pandemic period both at national and subnational scales. Our findings suggest that there may have been a substantial number of unreported Lyme disease cases despite an apparent increase in greenspace utilization. The use of counterfactual modeling using spatial and historical trends can provide insight into the likely numbers of missed cases. Variable ascertainment of cases has implications for passive surveillance programs, especially in the trending of disease morbidity and outbreak detection, suggesting that other methods may be appropriate for outbreak detection during disturbances to these passive surveillance systems.

Clinical surveillance systems obscure the true cholera infection burden in an endemic region

Our understanding of cholera transmission and burden largely relies on clinic-based surveillance, which can obscure trends, bias burden estimates and limit the impact of targeted cholera-prevention measures. Serological surveillance provides a complementary approach to monitoring infections, although the link between serologically derived infections and medically attended disease incidence—shaped by immunological, behavioral and clinical factors—remains poorly understood. We unravel this cascade in a cholera-endemic Bangladeshi community by integrating clinic-based surveillance, healthcare-seeking and longitudinal serological data through statistical modeling. Combining the serological trajectories with a reconstructed incidence timeline of symptomatic cholera, we estimated an annual Vibrio cholerae O1 infection incidence rate of 535 per 1,000 population (95% credible interval 514–556), with incidence increasing by age group. Clinic-based surveillance alone underestimated the number of infections and reported cases were not consistently correlated with infection timing. Of the infections, 4 in 3,280 resulted in symptoms, only 1 of which was reported through the surveillance system. These results impart insights into cholera transmission dynamics and burden in the epicenter of the seventh cholera pandemic, where >50% of our study population had an annual V. cholerae O1 infection, and emphasize the potential for a biased view of disease burden and infection risk when depending solely on clinical surveillance data.

Utility of surveillance data for planning for dengue elimination in Yogyakarta, Indonesia: a scenario-tree modelling approach

IntroductionField trials and modelling studies suggest that elimination of dengue transmission may be possible through widespread release of Aedes aegypti mosquitoes infected with the insect bacterium Wolbachia pipientis (wMel strain),...

Gastroenteritis Forecasting Assessing the Use of Web and Electronic Health Record Data With a Linear and a Nonlinear Approach: Comparison Study.

Disease surveillance systems capable of producing accurate real-time and short-term forecasts can help public health officials design timely public health interventions to mitigate the effects of disease outbreaks in affected populations. In France, existing clinic-based disease surveillance systems produce gastroenteritis activity information that lags real time by 1 to 3 weeks. This temporal data gap prevents public health officials from having a timely epidemiological characterization of this disease at any point in time and thus leads to the design of interventions that do not take into consideration the most recent changes in dynamics. The goal of this study was to evaluate the feasibility of using internet search query trends and electronic health records to predict acute gastroenteritis (AG) incidence rates in near real time, at the national and regional scales, and for long-term forecasts (up to 10 weeks). We present 2 different approaches (linear and nonlinear) that produce real-time estimates, short-term forecasts, and long-term forecasts of AG activity at 2 different spatial scales in France (national and regional). Both approaches leverage disparate data sources that include disease-related internet search activity, electronic health record data, and historical disease activity. Our results suggest that all data sources contribute to improving gastroenteritis surveillance for long-term forecasts with the prominent predictive power of historical data owing to the strong seasonal dynamics of this disease. The methods we developed could help reduce the impact of the AG peak by making it possible to anticipate increased activity by up to 10 weeks.

Telemedicine with a Cell-Free DNA Based Monitoring Approach Maintains Lung Allograft Function While Reducing Frequency of Invasive Bronchoscopy

Purpose The need to reduce in-person clinic visits during the COVID-19 pandemic necessitated a significant reduction in traditional lung transplant surveillance with bronchoscopy and clinic-based pulmonary function testing (PFT). We hypothesized that a screening strategy that utilized cell free DNA (CareDx: Allosure), a non-invasive marker of molecular allograft injury, to determine the need for for-cause diagnostics would yield equivalent lung function stability as traditional monitoring using surveillance bronchoscopy and clinic performed PFTs in lung transplant recipients. Methods We compared the change in FEV1, the prevalence of donor-specific HLA antibodies (DSA), and frequency of hospitalization over parallel 6-month timespans in 2 cohorts of LTRs assessed during the 1st 3 years of their transplant. The 1st cohort (N=65) was monitored from 3/2019 to 9/2019 by in-clinic PFT, surveillance bronchoscopy, DSA, and the 2nd cohort (N=73) was monitored from 3/2020-9/2020 with telemedicine, home spirometry, surveillance dd-cfDNA, and DSA testing every 1-3 months. In cohort 2, patients with >10% decline in home FEV1, and/or dd-cfDNA>1% underwent for-cause bronchoscopy and/or further diagnostic evaluation. Surveillance PFTs were conducted once between 7/20 and 9/20 in cohort 2 to assess the stability of lung function. For both cohorts, a minimum interval of 150 days and a maximum interval of 200 days was used for analysis of spirometric change. Results There were significantly fewer bronchoscopies/patient (pt) in cohort 2 vs cohort 1 (0.91 vs 1.8, p Conclusion The use of non-invasive cell-free DNA testing with home spirometry screening appears to yield comparable medium-term allograft outcomes, as compared to conventional clinic-based PFTs and surveillance bronchoscopy. Further multi-center studies are warranted to determine if this approach can reduce invasive procedures while maintaining equivalent outcomes in clinically meaningful parameters.

Precision public health through clinic-based syndromic surveillance in communities

ObjectiveSentinel physician surveillance in the communities has played an important role in detecting early aberrations in epidemics. The traditional approach is to ask primary care physicians to actively report some diseases such as influenza-like illness (ILI), and hand, foot, and mouth disease (HFMD) to health authorities on a weekly basis. However, this is labor-intensive and time-consuming work. In this study, we try to set up an automatic sentinel surveillance system to detect 23 syndromic groups in the communites.IntroductionIn December 2009, Taiwan’s CDC stopped its sentinel physician surveillance system. Currently, infectious disease surveillance systems in Taiwan rely on not only the national notifiable disease surveillance system but also real-time outbreak and disease surveillance (RODS) from emergency rooms, and the outpatient and hospitalization surveillance system from National Health Insurance data. However, the timeliness of data exchange and the number of monitored syndromic groups are limited. The spatial resolution of monitoring units is also too coarse, at the city level. Those systems can capture the epidemic situation at the nationwide level, but have difficulty reflecting the real epidemic situation in communities in a timely manner. Based on past epidemic experience, daily and small area surveillance can detect early aberrations. In addition, emerging infectious diseases do not have typical symptoms at the early stage of an epidemic. Traditional disease-based reporting systems cannot capture this kind of signal. Therefore, we have set up a clinic-based surveillance system to monitor 23 kinds of syndromic groups. Through longitudinal surveillance and sensitive statistical models, the system can automatically remind medical practitioners of the epidemic situation of different syndromic groups, and will help them remain vigilant to susceptible patients. Local health departments can take action based on aberrations to prevent an epidemic from getting worse and to reduce the severity of the infected cases.MethodsWe collected data on 23 syndromic groups from participating clinics in Taipei City (in northern Taiwan) and Kaohsiung City (in southern Taiwan). The definitions of 21 of those syndromic groups with ICD-10 diagnoses were adopted from the International Society for Disease Surveillance (https://www.surveillancerepository.org/icd-10-cm-master-mapping-reference-table). The definitions of the other two syndromic groups, including dengue-like illness and enterovirus-like illness, were suggested by infectious disease and emergency medicine specialists.An enhanced sentinel surveillance system named “Sentinel plus” was designed for sentinel clinics and community hospitals. The system was designed with an interactive interface and statistical models for aberration detection. The data will be computed for different combinations of syndromic groups, age groups and gender groups. Every day, each participating clinic will automatically upload the data to the provider of the health information system (HIS) and then the data will be transferred to the research team.This study was approved by the committee of the Institutional Review Board (IRB) at Academia Sinica (AS-IRB02-106262, and AS-IRB02-107139). The databases we used were all stripped of identifying information and thus informed consent of participants was not required.ResultsThis system started to recruit the clinics in May 2018. As of August 2018, there are 89 clinics in Kaohsiung City and 33 clinics and seven community hospitals in Taipei City participating in Sentinel plus. The recruiting process is still ongoing. On average, the monitored volumes of outpatient visits in Kaohsiung City and Taipei City are 5,000 and 14,000 per day.Each clinic is provided one list informing them of the relative importance of syndromic groups, the age distribution of each syndromic group and a time-series chart of outpatient rates at their own clinic. In addition, they can also view the village-level risk map, with different alert colors. In this way, medical practitioners can know what’s going on, not only in their own clinics and communities but also in the surrounding communities.The Department of Health (Figure 1) can know the current increasing and decreasing trends of 23 syndromic groups by red and blue color, respectively. The spatial resolution has four levels including city, township, village and clinic. The map and bar chart represent the difference in outpatient rate between yesterday and the average for the past week. The line chart represents the daily outpatient rates for one selected syndromic group in the past seven days. The age distribution of each syndromic group and age-specific outpatient rates in different syndromic groups can be examined.ConclusionsSentinel plus is still at the early stage of development. The timeliness and the accuracy of the system will be evaluated by comparing with some syndromic groups in emergency rooms and the national notifiable disease surveillance system. The system is designed to assist with surveillance of not only infectious diseases but also some chronic diseases such as asthma. Integrating with external environmental data, Sentinel plus can alert public health workers to implement better intervention for the right population.

Clinical respiratory infections and pneumonia during the Hajj pilgrimage: A systematic review.

BackgroundThe Islamic Hajj pilgrimage to Mecca is one of the world's largest annual mass gatherings. Inevitable overcrowding during the pilgrims' stay greatly increases the risk of acquiring and spreading infectious diseases, especially respiratory diseases.MethodThe MEDLINE/PubMed and Scopus databases were searched for all relevant papers published prior to February 2018 that evaluated the prevalence of clinical symptoms of respiratory infections, including pneumonia, among Hajj pilgrims, as well as their influenza and pneumococcal vaccination status.ResultsA total of 61 papers were included in the review. Both cohort- and hospital-based studies provide complementary data, and both are therefore necessary to provide a complete picture of the total burden of respiratory diseases during the Hajj. Respiratory symptoms have been common among Hajj pilgrims over the last 15 years. In cohorts of pilgrims, cough ranged from 1.9% to 91.5%. However, the prevalence rates of the most common symptoms (cough, sore throat, and subjective fever) of influenza-like illness (ILI) varied widely across the included studies. These studies have shown variable results, with overall rates of ILI ranging from 8% to 78.2%. These differences might result from differences in study design, study period, and rates of vaccination against seasonal influenza that ranged from 1.1% to 100% among study participants. Moreover, the definition of ILI was inconsistent across studies. In hospitalized Hajj pilgrims, the prevalence of pneumonia, that remains a major concern in critically ill patients, ranged from 0.2% to 54.8%.ConclusionsLarge multinational follow-up studies are recommended for clinic-based syndromic surveillance, in conjunction with microbiological surveillance. Matched cohorts ensure better comparability across studies. However, study design and data collection procedures should be standardized to facilitate reporting and to achieve comparability between studies. Furthermore, the definition of ILI, and of most common symptoms used to define respiratory infections (e.g., upper respiratory tract infection), need to be precisely defined and consistently used. Future studies need to address potential effect of influenza and pneumococcal vaccine in the context of the Hajj pilgrimage.

Molecular and antigenic characterization of group C orthobunyaviruses isolated in Peru.

Group C orthobunyaviruses (GRCVs) are a complex of viruses in the genus Orthobunyavirus and are associated with human febrile disease in tropical and subtropical areas of South and Central America. While numerous GRCVs have been isolated from mosquitoes, animals, and humans, genetic analysis of these viruses is limited. In this study, we characterized 65 GRCV isolates from febrile patients identified through clinic-based surveillance in the northern and southern Peruvian Amazon. A 500 base pair region of the S segment and 750 base pair regions of the M and L segments were sequenced. Pairwise sequence analysis of the clinical isolates showed nucleotide identities ranging from 68% to 100% and deduced amino acid sequence identities ranging from 72% to 100%. Sequences were compared with reference strains of the following GRCVs: Caraparu virus (CARV), Murutucu virus (MURV), Oriboca virus (ORIV), Marituba virus (MTBV), Itaqui virus (ITQV), Apeu virus (APEUV), and Madrid virus (MADV). Sequence comparison of clinical isolates with the prototype strains based on the S and L segments identified two clades; clade I included isolates with high genetic association with CARV-MADV, and clade II included isolates with high genetic association with MURV, ORIV, APEUV, and MTBV. Genetic relationships based on the M segment were at time inconsistent with those based on the S and L segments. However, clade groupings based on the M segment were highly consistent with relationships based on microneutralization assays. These results advance our understanding of the genetic and serologic relationships of GRCVs circulating in the Peruvian Amazon.

Estimation of community-level influenza-associated illness in a low resource rural setting in India.

ObjectiveTo estimate rates of community-level influenza-like-illness (ILI) and influenza-associated ILI in rural north India.MethodsDuring 2011, we conducted household-based healthcare utilization surveys (HUS) for any acute medical illness (AMI) in preceding 14days among residents of 28villages of Ballabgarh, in north India. Concurrently, we conducted clinic-based surveillance (CBS) in the area for AMI episodes with illness onset ≤3days and collected nasal and throat swabs for influenza virus testing using real-time polymerase chain reaction. Retrospectively, we applied ILI case definition (measured/reported fever and cough) to HUS and CBS data. We attributed 14days of risk-time per person surveyed in HUS and estimated community ILI rate by dividing the number of ILI cases in HUS by total risk-time. We used CBS data on influenza positivity and applied it to HUS-based community ILI rates by age, month, and clinic type, to estimate the community influenza-associated ILI rates.FindingsThe HUS of 69,369 residents during the year generated risk-time of 3945 person-years (p-y) and identified 150 (5%, 95%CI: 4–6) ILI episodes (38 ILI episodes/1,000 p-y; 95% CI 32–44). Among 1,372 ILI cases enrolled from clinics, 126 (9%; 95% CI 8–11) had laboratory-confirmed influenza (A (H3N2) = 72; B = 54). After adjusting for age, month, and clinic type, overall influenza-associated ILI rate was 4.8/1,000 p-y; rates were highest among children <5 years (13; 95% CI: 4–29) and persons≥60 years (11; 95%CI: 2–30).ConclusionWe present a novel way to use HUS and CBS data to generate estimates of community burden of influenza. Although the confidence intervals overlapped considerably, higher point estimates for burden among young children and older adults shows the utility for exploring the value of influenza vaccination among target groups.

Burden of Influenza-like Illness Among Military Personnel Receiving Advanced Training at Ft. Sam Houston, TX

BackgroundInfluenza-like illness (ILI) places a significant burden on operational readiness in the U.S. military, particularly in trainees who live and work in congregated settings. ILI incidence rates for the trainees are based on passive surveillance of those presenting to medical clinics. Such clinic-based surveillance may under-estimate the true ILI burden because trainees with ILI may not seek health care due to mild symptoms or fear of missing training. We aimed to estimate the hidden ILI burden among trainees and behaviors related to healthcare seeking for ILI.MethodsA 1-page voluntary, anonymous ILI survey was administered during the end of program sessions for military medical trainees at Fort Sam Houston (JBSA-FSH), TX. The survey was started in January 2017 and is ongoing.ResultsBetween January and April 2017, 724 surveys were returned: respondents were aged 17–42 years (median 20 yo), 299 (41%) were female, and 442 (62%) white. The trainees maintained a healthy and active life style: 94% exercised at least 3 times a week; 79% never smoked and only 3% were obese. Overall, 68% trainees reported ILI symptoms during training: the proportion decreased from 75% in January to 46% in April (P-for-trend <0.01). History of travel and self-reported contact to people with ILI were associated with reporting having ILI. Of those reporting ILI, only 36% sought health care, and the proportion did not change over the four month period. Females were more likely to seek health care if they developed ILI: 43% of females vs. 31% of males (P = 0.02). While the majority of trainees washed their hands or used hand sanitizer at least 4 times a day, only 60% of trainees washed their hands after covering their mouth/nose for a sneeze, which may facilitate ILI circulation in the population.ConclusionAmong young and healthy medical trainees at JBSA-FSH, ILI was reported frequently during winter and decreased in spring. Trainees often did not seek health care for mild symptoms. The high prevalence of self-reported ILI among trainees despite their healthy life styles and good daily hand hygiene warrants further study. A better understanding of the impact of self-reported ILI on performance and of factors associated with health-care seeking are needed.Disclosures All authors: No reported disclosures.

Ambulatory Pediatric Surveillance of Hand, Foot and Mouth Disease as Signal of an Outbreak of Coxsackievirus A6 Infections, France, 2014-2015.

The clinical impact of enteroviruses associated with hand, foot and mouth disease (HFMD) is unknown outside Asia, and the prevalence of enterovirus A71 (EV-A71) in particular might be underestimated. To investigate the prevalence of enterovirus serotypes and the clinical presentations associated with HFMD in France, we conducted prospective ambulatory clinic-based surveillance of children during April 2014-March 2015. Throat or buccal swabs were collected from children with HFMD and tested for the enterovirus genome. Physical examinations were recorded on a standardized form. An enterovirus infection was detected in 523 (79.3%) of 659 children tested. Two epidemic waves occurred, dominated by coxsackievirus (CV) A6, which was detected in 53.9% of enterovirus-infected children. CV-A6 was more frequently related to atypical HFMD manifestations (eruptions extended to limbs and face). Early awareness and documentation of HFMD outbreaks can be achieved by syndromic surveillance of HFMD by ambulatory pediatricians and rapid enterovirus testing and genotyping.

HIV surveillance in Rwanda: readiness assessment to transition from antenatal care-based to prevention of mother-to-child transmission program-based HIV surveillance

In 2013, the World Health Organization (WHO) recommended that for efficiency and ethical considerations, transitioning from antenatal clinic-based surveillance to prevention of mother-to-child transmission (PMTCT)-based routine data should be investigated. An assessment of the readiness for this transition was carried out in Rwanda in 2011 and 2013. This assessment applied the WHO recommended method. Individual HIV rapid testing at site was compared to antenatal surveillance results at all existing 30 sites, involving 13 292 women. In addition, PMTCT HIV testing quality assurance and PMTCT routine data quality were assessed at 27 out of the 30 sites. All sentinel sites provided PMTCT services and had a high uptake of HIV testing (more than 90%). At all sites, PMTCT data were recorded in longitudinal and standardized antenatal clinic registers. Twenty-six out of 27 sites had HIV result completeness above 90%. A positive percentage agreement of 97.5% and negative percentage agreement of 99.9% were observed between routine PMTCT and sero-surveillance HIV test results. Of 27 sites, 25 scored more than 80% in all phases of HIV testing quality assurance. According to WHO standards, Rwanda antenatal care HIV sero-surveillance is ready to transition to PMTCT-based sero-surveillance.

Rickettsial Disease in the Peruvian Amazon Basin

Using a large, passive, clinic-based surveillance program in Iquitos, Peru, we characterized the prevalence of rickettsial infections among undifferentiated febrile cases and obtained evidence of pathogen transmission in potential domestic reservoir contacts and their ectoparasites. Blood specimens from humans and animals were assayed for spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) by ELISA and/or PCR; ectoparasites were screened by PCR. Logistic regression was used to determine associations between patient history, demographic characteristics of participants and symptoms, clinical findings and outcome of rickettsial infection. Of the 2,054 enrolled participants, almost 2% showed evidence of seroconversion or a 4-fold rise in antibody titers specific for rickettsiae between acute and convalescent blood samples. Of 190 fleas (Ctenocephalides felis) and 60 ticks (Rhipicephalus sanguineus) tested, 185 (97.4%) and 3 (5%), respectively, were positive for Rickettsia spp. Candidatus Rickettsia asemboensis was identified in 100% and 33% of the fleas and ticks tested, respectively. Collectively, our serologic data indicates that human pathogenic SFGR are present in the Peruvian Amazon and pose a significant risk of infection to individuals exposed to wild, domestic and peri-domestic animals and their ectoparasites.

Evaluation of Kenya's readiness to transition from sentinel surveillance to routine HIV testing for antenatal clinic-based HIV surveillance.

BackgroundSentinel surveillance for HIV among women attending antenatal clinics using unlinked anonymous testing is a cornerstone of HIV surveillance in sub-Saharan Africa. Increased use of routine antenatal HIV testing allows consideration of using these programmatic data rather than sentinel surveillance data for HIV surveillance.MethodsTo gauge Kenya’s readiness to discontinue sentinel surveillance, we evaluated whether recommended World Health Organization standards were fulfilled by conducting data and administrative reviews of antenatal clinics that offered both routine testing and sentinel surveillance in 2010.ResultsThe proportion of tests that were HIV-positive among women aged 15–49 years was 6.2 % (95 % confidence interval [CI] 4.6–7.7 %] in sentinel surveillance and 6.5 % (95 % CI 5.1–8.0 %) in routine testing. The agreement of HIV test results between sentinel surveillance and routine testing was 98.0 %, but 24.1 % of specimens that tested positive in sentinel surveillance were recorded as negative in routine testing. Data completeness was moderate, with HIV test results recorded for 87.8 % of women who received routine testing.ConclusionsAdditional preparation is required before routine antenatal HIV testing data can supplant sentinel surveillance in Kenya. As the quality of program data has markedly improved since 2010 a repeat evaluation of the use of routine antenatal HIV testing data in lieu of ANC sentinel surveillance is recommended.

Population Density, Poor Sanitation, and Enteric Infections in Nueva Santa Rosa, Guatemala.

Poor sanitation could pose greater risk for enteric pathogen transmission at higher human population densities because of greater potential for pathogens to infect new hosts through environmentally mediated and person-to-person transmission. We hypothesized that incidence and prevalence of diarrhea, enteric protozoans, and soil-transmitted helminth infections would be higher in high-population-density areas compared with low-population-density areas, and that poor sanitation would pose greater risk for these enteric infections at high density compared with low density. We tested our hypotheses using 6 years of clinic-based diarrhea surveillance (2007–2013) including 4,360 geolocated diarrhea cases tested for 13 pathogens and a 2010 cross-sectional survey that measured environmental exposures from 204 households (920 people) and tested 701 stool specimens for enteric parasites. We found that population density was not a key determinant of enteric infection nor a strong effect modifier of risk posed by poor household sanitation in this setting.

Incomplete Protection against Dengue Virus Type 2 Re-infection in Peru.

BackgroundNearly half of the world’s population is at risk for dengue, yet no licensed vaccine or anti-viral drug is currently available. Dengue is caused by any of four dengue virus serotypes (DENV-1 through DENV-4), and infection by a DENV serotype is assumed to provide life-long protection against re-infection by that serotype. We investigated the validity of this fundamental assumption during a large dengue epidemic caused by DENV-2 in Iquitos, Peru, in 2010–2011, 15 years after the first outbreak of DENV-2 in the region.Methodology/Principal FindingsWe estimated the age-dependent prevalence of serotype-specific DENV antibodies from longitudinal cohort studies conducted between 1993 and 2010. During the 2010–2011 epidemic, active dengue cases were identified through active community- and clinic-based febrile surveillance studies, and acute inapparent DENV infections were identified through contact tracing studies. Based on the age-specific prevalence of DENV-2 neutralizing antibodies, the age distribution of DENV-2 cases was markedly older than expected. Homologous protection was estimated at 35.1% (95% confidence interval: 0%–65.2%). At the individual level, pre-existing DENV-2 antibodies were associated with an incomplete reduction in the frequency of symptoms. Among dengue cases, 43% (26/66) exhibited elevated DENV-2 neutralizing antibody titers for years prior to infection, compared with 76% (13/17) of inapparent infections (age-adjusted odds ratio: 4.2; 95% confidence interval: 1.1–17.7).Conclusions/SignificanceOur data indicate that protection from homologous DENV re-infection may be incomplete in some circumstances, which provides context for the limited vaccine efficacy against DENV-2 in recent trials. Further studies are warranted to confirm this phenomenon and to evaluate the potential role of incomplete homologous protection in DENV transmission dynamics.

Examining clinic-based and public health approaches to ascertainment of HIV care status.

Clinic-based tracing efforts and public health surveillance data can provide different information about HIV care status for the same patients. The relative yield and how best to use these sources to identify and reengage out-of-care patients is unknown. At a large public HIV clinic in San Francisco, we selected a 10% random sample of active patients who were at least 210 days "late" for an HIV primary care visit as of April 1, 2013, for clinic-based outreach. Patients were considered out of care if they did not have an HIV primary care visit in the 210 days before April 1, 2013. We then matched the sample with the San Francisco Department of Public Health HIV surveillance registry. Patients with a CD4 or viral load result in the 210-day period were classified as in care. We compared results from both sources and estimated the cumulative incidence of disengagement from care for the full cohort of clinic patients. Of 940 patients lost to follow-up, 95 were sampled. Clinic tracing found 60 (63%) in care, 23 (24%) not located, 9 (10%) out of care, 2 (2%) incarcerated, and 1 (1%) had died. Of 42 individuals surveillance classified as out of care, tracing found 22 (52%) were in care. Of 52 patients found to be in care by surveillance, 12 (23%) were out of care by clinic tracing or unable to be located. The naive estimate of the cumulative incidence of disengagement from care at 3 years for the active clinic cohort was 41.1% [95% confidence interval (CI): 37.6 to 44.5]. The use of surveillance data reduced this estimate to 12.7% (95% CI: 18.2 to 25.4), and when further corrected using tracing outcomes, the estimate dropped to only 6.4% (95% CI: 3.4 to 9.4). Clinic-based tracing and surveillance data together provide a better understanding of care status than either method alone. Using surveillance data to inform clinic-based outreach efforts may be an effective strategy, although tracing efforts are most likely to be successful if conducted in real time.

The epidemiology and aetiology of diarrhoeal disease in infancy in southern Vietnam: a birth cohort study

Previous studies indicate a high burden of diarrhoeal disease in Vietnamese children, however longitudinal community-based data on burden and aetiology are limited. The findings from a large, prospective cohort study of diarrhoeal disease in infants in southern Vietnam are presented herein. Infants were enrolled at birth in urban Ho Chi Minh City and a semi-rural district in southern Vietnam, and followed for 12 months (n=6706). Diarrhoeal illness episodes were identified through clinic-based passive surveillance, hospital admissions, and self-reports. The minimum incidence of diarrhoeal illness in the first year of life was 271/1000 infant-years of observation for the whole cohort. Rotavirus was the most commonly detected pathogen (50% of positive samples), followed by norovirus (24%), Campylobacter (20%), Salmonella (18%), and Shigella (16%). Repeat infections were identified in 9% of infants infected with rotavirus, norovirus, Shigella, or Campylobacter, and 13% of those with Salmonella infections. The minimum incidence of diarrhoeal disease in infants in both urban and semi-rural settings in southern Vietnam was quantified prospectively. A large proportion of laboratory-diagnosed disease was caused by rotavirus and norovirus. These data highlight the unmet need for a rotavirus vaccine in Vietnam and provide evidence of the previously unrecognized burden of norovirus in infants.

Sexually Transmitted Infection Trends Among Gay or Bisexual Men From a Clinic-Based Sentinel Surveillance System in British Columbia, Canada

We described trends for sexually transmitted infections (STI) among gay/bisexual men in British Columbia, Canada, using a sentinel site surveillance approach. Using data from an electronic charting system, we included gay/bisexual men who visited high-volume STI clinics from 2000 to 2013. Diagnosis rates and incidence density were calculated for chlamydia, gonorrhea, syphilis, HIV, hepatitis C, genital herpes, and genital warts. Incidence density was estimated among repeat testers who converted from a negative to positive test result. We also conducted Poisson regression analysis to determine factors that were associated with increased incidence rates. A total of 47,170 visits were identified for gay/bisexual men during our time frame. The median age was 34 years (interquartile range, 27-43 years), and most clients were seen in Vancouver. Although trends for most STI were stable, diagnoses of gonorrhea and syphilis have risen steadily in recent years. Coinfection with HIV was associated with higher gonorrhea and syphilis rates in the Poisson regression model. In addition, visiting a Vancouver clinic and younger age were associated with increased incidence. Our clinic-based sentinel surveillance system found increasing trends for gonorrhea and syphilis among gay/bisexual men but not for other STI in British Columbia. Further investigation is required to explore the syndemic effects of syphilis, gonorrhea, and HIV. This new platform will be a valuable tool for ongoing monitoring of STI and targeting prevention efforts.

Long-term and seasonal dynamics of dengue in Iquitos, Peru.

IntroductionLong-term disease surveillance data provide a basis for studying drivers of pathogen transmission dynamics. Dengue is a mosquito-borne disease caused by four distinct, but related, viruses (DENV-1-4) that potentially affect over half the world's population. Dengue incidence varies seasonally and on longer time scales, presumably driven by the interaction of climate and host susceptibility. Precise understanding of dengue dynamics is constrained, however, by the relative paucity of laboratory-confirmed longitudinal data.MethodsWe studied 10 years (2000–2010) of laboratory-confirmed, clinic-based surveillance data collected in Iquitos, Peru. We characterized inter and intra-annual patterns of dengue dynamics on a weekly time scale using wavelet analysis. We explored the relationships of case counts to climatic variables with cross-correlation maps on annual and trimester bases.FindingsTransmission was dominated by single serotypes, first DENV-3 (2001–2007) then DENV-4 (2008–2010). After 2003, incidence fluctuated inter-annually with outbreaks usually occurring between October and April. We detected a strong positive autocorrelation in case counts at a lag of ∼70 weeks, indicating a shift in the timing of peak incidence year-to-year. All climatic variables showed modest seasonality and correlated weakly with the number of reported dengue cases across a range of time lags. Cases were reduced after citywide insecticide fumigation if conducted early in the transmission season.ConclusionsDengue case counts peaked seasonally despite limited intra-annual variation in climate conditions. Contrary to expectations for this mosquito-borne disease, no climatic variable considered exhibited a strong relationship with transmission. Vector control operations did, however, appear to have a significant impact on transmission some years. Our results indicate that a complicated interplay of factors underlie DENV transmission in contexts such as Iquitos.