Surveillance fatigue (fatigatio vigilantiae) during epidemics

Revista-Chilena-de-Infectologia-3-2017

Comunicación Breve Figure 1. Example of surveillance fatigue. The accumulative number of disease cases reported at the initial stage of an ongoing epidemic may reflect the number of cases properly (continuous straight line). As the time continues, the efficacy of case reporting decrease due to, for example, limited staff or laboratory supplies and high number of patients overwhelming health systems (arrow). This can result in incomplete number of cases reported (continuous curve line), not reflecting real number of cases (dashed line). www.sochinf.cl 291 Surveillance fatigue (fatigatio vigilantiae) during epidemics Daniel Romero-Álvarez, A. Townsend Peterson and Luis E. Escobar Fatiga de vigilancia (fatigatio vigilantiae) durante epidemias Se presenta el concepto de “fatiga de vigilancia” (fatigatio vigilantiae) para describir un escenario epidemiológico en el que es evidente el sub-reporte de casos durante epidemias abrumadoras. Revisamos epidemias pasadas y encontramos que la fatiga de vigilancia es un patrón común, por lo tanto, puede ser un concepto útil en la epidemiología moderna. Palabras clave: Epidemias; epidemiología; fatigatio vigilantiae; fatiga de vigilancia. Key words: Epidemics; epidemiology; fatigatio vigilantiae; surveillance fatigue. Introduction The collection, interpretation, and sharing of disease information to health agencies has been termed epidemiological surveillance. Surveillance data can evolve into hypotheses of causation and correlation but also in forecasts on which preventive strategies can be based. For example, at the beginning of the Zika virus epidemic in 2016, initial epidemiological data informed early warning systems1. However, passive and active epidemiological surveillance can be compromised, especially in developing countries2,3. Case description We present the concept of surveillance fatigue4, or fatigatio vigilantiae, defined as incomplete reporting of cases during or after periods of high disease incidence during an outbreak or epidemic. This underreporting will often occur in burgeoning epidemics that overload staff and resources of health institutions. Strikingly, such systemic underreporting may lead to incorrect decisions, affecting effectiveness of public health Hospital General Enrique Garcés, Quito, Ecuador. Unidad de Epidemiología (DRA). University of Kansas, Lawrence, Kansas, USA. Biodiversity Institute (ATP). University of Minnesota, St. Paul, Minnesota, USA. Department of Fisheries, Wildlife and Conservation Biology (LEE). Declaration of interests: The authors declare that there is no conflict of interest. Funding: This manuscript was not supported by any funding. Authors agree with the publication of the present manuscript. Recibido: 5 de agosto de 2016 / Aceptado: 14 de marzo de 2017 Correspondencia a: Luis E. Escobar lescobar@umn.edu interventions5. As an example, the explosive epidemic of Chikungunya in the Americas in 2014 resulted in health systems unable to detect and report all cases per country per week4, with an evident plateau in disease notification especially in countries with weak surveillance systems. Thus, numbers of Chikungunya cases did not reflect the size of the epidemic. Neglecting surveillance fatigue while building epidemiological indexes such as incidence or case fatality risk could mislead the magnitude of the epidemic6. Epidemiological studies at the beginning of an epidemic could correctly reflect numbers of people infected (Figure 1), but posterior limitations in laboratory supplies or personnel can lead to surveillance fatigue. For example, in the pandemic of influenza A H1N1 in 2009, countries with strong surveillance systems faced difficulties to maintain accurate case reporting due to overwhelming epidemic; in this scenario, laboratory diagnosis supplies were consumed before the peak of the epidemic, undermining surveillance7. During the Ebola epidemic in 2014, an underestimation of cases in Liberia was clearly identified and described in reports of the World Health Organization8. Such decrease of incidence was catalogued as ‘unlikely to be genuine’ due to noticeable evidence of underreporting8. During the yellow fever outbreak in Angola in 2016, local case notifications were delayed even with effective local surveillance and international support9. Rev Chilena Infectol 2017; 34 (3): 291-292


Revista-Chilena-de-Infectologia-3-2017
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