Use Of Capture-recapture Methods Research Articles

Airborne imagery does not preclude detectability issues in estimating bird colony size

Aerial images obtained by drones are increasingly used for ecological research such as wildlife monitoring. Yet detectability issues resulting from animal activity or visibility are rarely considered, although these may lead to biased population size and trend estimates. In this study, we investigated detectability in a census of Malagasy pond heron Ardeola idae colonies on the island of Mayotte. We conducted repeated drone flights over breeding colonies in mangrove habitats during two breeding seasons. We then identified individuals and nests in the images and fitted closed capture-recapture models on nest-detection histories. We observed seasonal variation in the relative abundance of individuals, and intra-daily variation in the relative abundance of individuals—especially immature birds—affecting the availability of nests for detection. The detection probability of nests estimated by capture–recapture varied between 0.58 and 0.74 depending on flyover days and decreased 25% from early to late morning. A simulation showed that three flyovers are necessary to detect a 5–6% decline in colonies of 50 to 200 nests. These results indicate that the detectability of nests of forest-canopy breeding species from airborne imagery can vary over space and time; we recommend the use of capture-recapture methods to control for this bias.

Novel Use of Capture-Recapture Methods to Estimate Completeness of Contact Tracing during an Ebola Outbreak, Democratic Republic of the Congo, 2018-2020.

Despite its critical role in containing outbreaks, the efficacy of contact tracing, measured as the sensitivity of case detection, remains an elusive metric. We estimated the sensitivity of contact tracing by applying unilist capture-recapture methods on data from the 2018–2020 outbreak of Ebola virus disease in the Democratic Republic of the Congo. To compute sensitivity, we applied different distributional assumptions to the zero-truncated count data to estimate the number of unobserved case-patients with any contacts and infected contacts. Geometric distributions were the best-fitting models. Our results indicate that contact tracing efforts identified almost all (n = 792, 99%) of case-patients with any contacts but only half (n = 207, 48%) of case-patients with infected contacts, suggesting that contact tracing efforts performed well at identifying contacts during the listing stage but performed poorly during the contact follow-up stage. We discuss extensions to our work and potential applications for the ongoing coronavirus pandemic.

The use of capture-recapture methods to provide better estimates of the burden of norovirus outbreaks from seafood in England, 2004-2011.

Norovirus (NoV) is the greatest cause of infectious intestinal disease in the UK. The burden associated with foodborne outbreaks is underestimated in part because data are dispersed across different organisations. Each looks at outbreaks through a different lens. To estimate the burden of NoV from seafood including shellfish we used a capture-recapture technique using datasets from three different organisations currently involved in collecting information on outbreaks. The number of outbreaks of NoV related to seafood including shellfish in England was estimated for the period of 2004-2011. The combined estimates were more than three times as high (N = 360 using Chao's sample coverage approach) as the individual count from organisation three (N = 115), which captured more outbreaks than the other two organisations. The estimates were calculated for both independence and dependence between the datasets. There was evidence of under-reporting of NoV outbreaks and inconsistency of reporting between organisations, which means that, currently, more than one data source needs to be used to estimate as accurately as possible the total number of NoV outbreaks and associated cases. Furthermore, either the integration of reporting mechanisms or simplifying the process of reporting outbreaks to organisations is essential for understanding and, hence, controlling disease burden.

Capture-Recapture Estimators in Epidemiology with Applications to Pertussis and Pneumococcal Invasive Disease Surveillance.

IntroductionSurveillance networks are often not exhaustive nor completely complementary. In such situations, capture-recapture methods can be used for incidence estimation. The choice of estimator and their robustness with respect to the homogeneity and independence assumptions are however not well documented.MethodsWe investigated the performance of five different capture-recapture estimators in a simulation study. Eight different scenarios were used to detect and combine case-information. The scenarios increasingly violated assumptions of independence of samples and homogeneity of detection probabilities. Belgian datasets on invasive pneumococcal disease (IPD) and pertussis provided motivating examples.ResultsNo estimator was unbiased in all scenarios. Performance of the parametric estimators depended on how much of the dependency and heterogeneity were correctly modelled. Model building was limited by parameter estimability, availability of additional information (e.g. covariates) and the possibilities inherent to the method. In the most complex scenario, methods that allowed for detection probabilities conditional on previous detections estimated the total population size within a 20–30% error-range. Parametric estimators remained stable if individual data sources lost up to 50% of their data. The investigated non-parametric methods were more susceptible to data loss and their performance was linked to the dependence between samples; overestimating in scenarios with little dependence, underestimating in others. Issues with parameter estimability made it impossible to model all suggested relations between samples for the IPD and pertussis datasets. For IPD, the estimates for the Belgian incidence for cases aged 50 years and older ranged from 44 to58/100,000 in 2010. The estimates for pertussis (all ages, Belgium, 2014) ranged from 24.2 to30.8/100,000.ConclusionWe encourage the use of capture-recapture methods, but epidemiologists should preferably include datasets for which the underlying dependency structure is not too complex, a priori investigate this structure, compensate for it within the model and interpret the results with the remaining unmodelled heterogeneity in mind.

Using capture-recapture methods to better ascertain the incidence of fatal child maltreatment

Objectives To (1) test the use of capture-recapture methods to estimate the total number of child maltreatment deaths in a single state using information from death certificates, child welfare reports, child death review teams, and uniform crime reports; and to (2) compare these estimates to the number of maltreatment deaths identified through an in-depth “gold standard” review. Methods Child maltreatment deaths were identified in four existing administrative data sources: (1) death reports in our state vital statistics (DC); (2) child death review team reports (CDR); (3) homicide reports filed by our state police agency as uniform crime report (UCR) supplements for the FBI; and (4) abstracted reports of a minor's death from our state child protective services (CPS) agency. Capture-recapture pair-wise and pooled comparisons were then applied to estimate the numbers of abuse and total maltreatment deaths and were compared to the number of cases identified by independent case review. Results There were a total of 194 child maltreatment deaths in Michigan during 2000–2001 with 66 due to physical abuse. Capture-recapture analysis estimated the mean number of total child maltreatment deaths as 101.02 (95%CI = 92.52, 109.53), with abuse deaths of 64.55 (60.85, 68.25). Most pair-wise and pooled comparisons worked equally well for abuse deaths, but estimates for total child maltreatment deaths were low. Conclusions Capture-recapture methods applied to existing administrative datasets produced accurate estimates of child abuse deaths but were not useful in producing reliable estimates of total child maltreatment deaths due to undercounting neglect-related deaths in all existing administrative data sets. The underlying assumptions for capture-recapture methods were not met for neglect deaths. Local and/or state teams conducting ongoing intensive case review may yet remain the best way to identify the total number of child maltreatment deaths. Practice implications Capture-recapture methods allow for more accurate estimation of the true number of child physical abuse deaths than does using single existing sources of child fatality information, but deaths from causes other than abuse are undercounted. Child maltreatment fatality surveillance requires a systematic process and standard criteria for identifying cases of maltreatment, particularly neglect-related child deaths.

Abstract No. 2 Prevalences of the chronic idiopathic and metabolic photodermatoses in Scotland

We have attempted to estimate the prevalence of the idiopathic photodermatoses (except the usually seasonal polymorphic light eruption and juvenile spring eruption) and the cutaneous porphyrias in Scotland. Knowledge of the prevalence of these conditions may be useful (i) for planning care for our population, and (ii) because knowledge of prevalences in our population, compared with other populations, might help us to determine factors likely to be important in causing these disorders. The Photobiology Unit holds a database of patients assessed between 1978 and now. For this study the database was searched in January 2003. We have estimated population prevalences based on the assumptions (i) that we have investigated all patients with these conditions who live in appropriate catchment areas, (ii) that the population of these areas is as recorded in the 2001 Census, and (iii) that our local database accurately lists patients who are still alive and in our area. We estimated prevalences (per 100 000) as follows: chronic actinic dermatitis 16·5 (binomial ‘exact’ 95% confidence interval 13·7–19·7), porphyria cutanea tarda 7·6 (3·8–13·5), idiopathic solar urticaria 3·9 (2·6–5·6), actinic prurigo 3·3 (2·1–4·8), erythropoietic protoporphyria 2·3 (1·3–3·7), variegate porphyria 0·54 (0·15–1·4), hydroa vacciniforme 0·47 (0·03–0·71) and erythropoietic porphyria 0·04 (0·0048–0·14). Ideally, prevalences of these conditions should be determined by a population survey, or the use of capture-recapture methods. However, neither of these approaches is practical for these rare conditions for which there are not multiple comprehensive diagnostic databases. Our approach, despite all its flaws, gives better estimates than have until now been available for prevalences of most of these conditions. Acknowledgment and Disclaimer: Orfagen (France) provided funding for this study. This study has not been previously published but has been presented at a meeting of the Scottish Dermatological Society.

Hidden diabetes in the UK: use of capture-recapture methods to estimate total prevalence of diabetes mellitus in an urban population

An early requirement of the UK's Diabetes National Service Framework is enumeration of the total affected population. Existing estimates tend to be based on incomplete lists. In a study conducted over one year in North Liverpool, we compared crude prevalence rates for type 1 and type 2 diabetes with estimates obtained by capture-recapture (CR) analysis of multiple incomplete patient lists, to assess the extent of unascertained but diagnosed cases. Patient databases were constructed from six sources-a hospital diabetes centre; general practitioner registers; hospital admissions with a diagnosis of diabetes; a hospital diabetic retinal clinic; a research list of patients with diabetes admitted with stroke; and a local children's hospital. Log linear modelling was used to estimate missing cases, hence total prevalence. The crude prevalence of diabetes was 1.5% (95% confidence interval [CI] 1.41, 1.52), compared with a CR-adjusted rate of 3.1% (CI 3.03, 3.19). Age-banded CR-adjusted prevalence was always higher in males than in females and the difference became more pronounced with increasing age. Among males, CR-adjusted prevalence rose from 0.4% at age 10-19 years to 18.3% at 80+ years; in females the corresponding figures were 0.4% and 9.3%. The gap between crude and CR-estimated prevalence points to a rate of 'hidden diabetes' that has substantial implications for future diabetes care.

Re-Evaluation of Adult Survival of Black-Headed Gulls (Larus ridibundus) in Presence of Recapture Heterogeneity

An adequate knowledge of the growth rate of a population often is needed in conservation biology and population management. In long-lived species, annual adult survival is the demographic parameter that has the strongest influence on population growth rate. Adult survival often is estimated by capture-recapture methods under the restrictive assump- tion that all individuals in a given group have the same survival and recapture probabilities. Violation of this assumption, i.e. heterogeneity among individuals, tends to bias survival es- timates. In particular, heterogeneous capture probabilities independent of survival probabil- ities tend to negatively bias survival estimates. However, a cautious use of capture-recapture methods allows recognition of the problem and an accurate estimation of survival. We esti- mated adult survival in a population of Black-headed Gulls (Larus ridibundus) breeding in cen- tral France based on resightings of banded birds. The estimated survival was lower in the year after the first resighting than afterwards. We did not find any substantial biological explanation for this result (in particular, it was difficult to connect it with the existence of prospecting individuals). However, heterogeneity in the resighting probability, which is very likely in this population, could explain why apparent survival seemed lower in the year immediately after the first resighting. The higher value of the survival estimate (0.90) when capture-rate hetero-

Increasing use of heroine and cocaine in Switzerland since 1990: use of a generalized Poisson distribution in the collected data

Estimates of the prevalence of deviant behaviour, which are based on the usual survey methods are by far too low. Therefore, the use of capture-recapture methods or of the truncated Poisson distribution is to be preferred, provided appropriate data are available. Here an extended Poisson approach was applied in order to estimate the number of users of hard illegal drugs (heroin, cocaine) in Switzerland for each year from 1990 to 1993. These estimates indicate an increase by about 50% during the period 1990-1993.