Date Published: August 02, 2017
Publisher: The American Society of Tropical Medicine and Hygiene
Author(s): Claude Flamand, Camille Fritzell, Pauline Obale, Philippe Quenel, Jocelyn Raude.
Human behaviors are increasingly recognized to play a key role in the spread of infectious diseases. Although a set of social and cognitive determinants has been consistently found to affect the adoption of health protective behaviors aiming to control and prevent a variety of infections, little is currently known about the ecological drivers of these behaviors in epidemic settings. In this article, we took advantage of the outbreak of chikungunya, a reemerging mosquito-borne disease, that occurred in French Guiana in 2014–15 to test empirically the assumption proposed by Zielinski-Gutierrez and Hayden that the proximity of the disease and perceptions of the natural environment may considerably shape public response to an emerging health threat. To achieve this, a cross-sectional survey was conducted among high school students of the region (N = 1462) at an early stage of the epidemic. Surprisingly, spatial analysis of the collected data leads to counterintuitive results as the participants who lived in the most affected area expressed less concern about the disease and practiced preventive behaviors less frequently than did other participants. These paradoxical results may be attributed to the possible activation of risk denial processes which have previously been observed in the risk perception literature, and described by several social and psychological defensiveness theories.
Emerging and reemerging mosquito-borne diseases such as dengue fever, chikungunya, and zika represent a growing public health threat to tropical countries, especially American and Caribbean countries where a great number of large scale epidemics have been documented in recent years.1,2 In French Guiana, where the dengue virus has been responsible for several outbreaks over as many decades,3–5 a few locally acquired cases of chikungunya were reported in February 2014.6 Indeed, six biologically confirmed cases and 12 suspected cases were detected in Kourou municipality within a 200-m radius between February 19 and 27, confirming the first localized chain of chikungunya transmission in the American continent. The introduction and emergence of this new virus quickly triggered the implementation of various public health interventions including vector control, and awareness and prevention campaigns conducted by local health authorities. In the month following this first warning, the epidemiologic situation gradually evolved, as the number of clusters increased across the region.7 This led the public health authorities to implement the same control vector plan as for dengue fever.
In total, 1,462 students took part in the study, including 225 participants (19.3% [95% CI 17.1, 21.8]) from the municipality of Kourou, where the first geographic clusters of cases of chikungunya were observed. No parental refusal was reported to the investigators. On the basis of the data collected among high school students of French Guiana, symptomatic chikungunya prevalence rates were estimated at 0.8% (95% CI [0.4, 1.6]) in May 2014. No cases of chikungunya were reported in the city of Kourou among the students living in this high-risk geographical area. However, 69 students (4.5%) were absent during the survey period, though there was no significant difference in absenteeism among the three groups. By contrast, it should be noted that a personal history of dengue fever infection was reported by 45.6% (95% CI [40.1, 51.2]) of the Kourou participants, which was comparable to that of students living in the other areas (44.3% [95% CI (40.5, 48.2)]), since geographical difference was not significant.
Though behavioral changes in response to threatening events in modern societies were largely ignored for decades in the epidemiological literature, they have recently become the focus of a range of research studies. Interestingly, health and social behaviors are now increasingly recognized as playing a fundamental role in the emergence, spreading, and persistence of infectious diseases in the world.46,47 This is particularly true in the field of vector-borne diseases, for which active participation of communities and alteration of human behaviors at a local level have long been thought to be critical in the implementation of effective and sustainable programs of vector control aiming to reduce the risk of infection with mosquito-borne viruses.9–11 However, it should be acknowledged that much is still unknown about the determinants and drivers of health protective behaviors in epidemic settings. Indeed, the most important findings about health behaviors and their determinants are currently drawn from empirical studies conducted in the domain of chronic or degenerative diseases, such as cancers, diabetes, or cardiovascular diseases. To date, there has been little attempt to measure the cognitive and behavioral responses to a vector-borne disease immediately after its emergence in a naïve population. Therefore, we cannot exclude that there may exist substantial differences between the nature and drivers of health behaviors engaged in nonstressed environments, as compared with those activated in stressed environments.48
A number of possible limitations to our results should be reported. First, self-reports of preventive behaviors in surveys are known to have an uncertain relationship to the behaviors participants actually perform in their everyday life. Notably, self-reported behaviors in the health and safety domain are often subject to some biases attributable to the courtesy or social desirability effects. Nevertheless, there is no reason for assuming that this bias should be bigger in a low-risk area than in a high-risk area. Second, it is possible that some uninvestigated third factors, for example, a lower density of mosquito in Kourou, was responsible for the geographic differences observed in both beliefs and behaviors related to mosquito-borne diseases.54 Third, the survey was conducted among high school students who may have an understanding, attitudes, and perceptions that differ from those of the household members responsible for implementing control measures associated with vector-borne diseases. However, this target group, which was readily accessible and available, may represent a significant proxy for the household decision-makers. Furthermore, it was of interest to explore a young generation, which may be more easily involved in community-based vector source reduction campaigns. Last but not least, we cannot rule out the possibility that students absent during the survey period had been infected by CHIKV chikungunya. This may have led to an underestimation of the reported CHIKV chikungunya prevalence among students. Nevertheless, the overall epidemiologic situation, as reported by the public health authorities at the time of the survey, was characterized by a moderate autochthonous transmission and only 4.5% of the students registered in the surveyed classrooms were absent. Furthermore, we did not observe any significant differences in absenteeism between the various municipalities, which indicates that the interpretation of the results in terms of risk proximity is therefore unlikely to be a limitation.
To conclude, exposure and proximity to risk induced by an outbreak of vector-borne diseases was found to lead to additional knowledge in the exposed population, but not necessarily to the acknowledgment that the risk of infection can be avoided or reduced. When groups of people are confronted with an emerging health threat, they may neglect the warning from the public health authorities to maintain a positive image of their community and health environment, notably by minimizing perceived control of and exposure to the risk of contracting the illness. This motivational process leads them to leave their former habits and lifestyles unchanged and, as a consequence, to increase their risk of infection from vector-borne diseases. Therefore, the psychological processes activated during outbreaks may impede to a large extent programs developed by public health institutions to control and prevent the propagation of vector-borne diseases in epidemic settings. Interestingly, this propensity to deny or neglect health risks is relatively well-documented at an individual level. In terms of practical implications, it seems advisable to offer at the community level a monitoring of health protective actions carried out at regular intervals to make the gap between the actual and the recommended behaviors more visible. In the past years, this strategy has been relatively successful to promote physical activity and healthier diet.55,56 Moreover, as social comparisons are known to support behavior change,57 feedback from such investigations could be communicated to the various communities of the regions concerned by an outbreak to show them some of the inconsistencies. In this way, it is expected that such a feedback loop would provide groups of people with an ongoing understanding of their own protective behavior and whether it matches and is appropriate to the environmental need, thereby allowing them to adapt preventive behaviors in a dynamic way, within a constantly evolving epidemiological environment.