What caused the 2012 dengue outbreak in Pucallpa, Peru? A socio-ecological autopsy

Abstract

Dengue is highly endemic in Peru, with increases in transmission particularly since vector re-infestation of the country in the 1980s. Pucallpa, the second largest city in the Peruvian Amazon, experienced a large outbreak in 2012 that caused more than 10,000 cases and 13 deaths. To date, there has been limited research on dengue in the Peruvian Amazon outside of Iquitos, and no published review or critical analysis of the 2012 Pucallpa dengue outbreak. This study describes the incidence, surveillance, and control of dengue in Ucayali to understand the factors that contributed to the 2012 Pucallpa outbreak. We employed a socio-ecological autopsy approach to consider distal and proximal contributing factors, drawing on existing literature and interviews with key personnel involved in dengue control, surveillance and treatment in Ucayali. Spatio-temporal analysis showed that relative risk of dengue was higher in the northern districts of Calleria (RR = 2.18), Manantay (RR = 1.49) and Yarinacocha (RR = 1.25) compared to all other districts between 2004 and 2014. The seasonal occurrence of the 2012 outbreak is consistent with typical seasonal patterns for dengue incidence in the region. Our assessment suggests that the outbreak was proximally triggered by the introduction of a new virus serotype (DENV-2 Asian/America) to the region. Increased travel, rapid urbanization, and inadequate water management facilitated the potential for virus spread and transmission, both within Pucallpa and regionally. These triggers occurred within the context of failures in surveillance and control programming, including underfunded and ad hoc vector control. These findings have implications for future prevention and control of dengue in Ucayali as new diseases such as chikungunya and Zika threaten the region.

Dengue Incidence and Sociodemographic Conditions in Pucallpa, Peruvian Amazon: What Role for Modification of the Dengue–Temperature Relationship?

“…Figure 2 shows seasonal trends in dengue cases. The 2012 dengue outbreak also occurred during the rainy season, as a result of proximal and distal causes discussed in Charette et al 26 The average age of patients with dengue in Pucallpa during the study period was 23.9 years old (95% CI: 23.5-24.1) and 52% of all cases were female patients. The mean average weekly temperature (lagged 4 weeks) was 25.2°C in the dry season compared with 26.2°C in the rainy season.…”

“…25 The 2012 Pucallpa dengue outbreak highlights gaps in our understanding of how climatic and social determinants interact to drive disease epidemics. 26 With the increasing frequency of extreme weather events in the Peruvian Amazon, more research is needed on effective dengue prevention strategies based on an improved understanding of the interaction between social determinants, weather, and dengue incidence. 27,28 We address this gap in the literature by examining how meteorological exposures affected dengue incidence among different subpopulations-compared across different districts, genders, and ages-in Pucallpa, Peru, from 2004 to 2014.…”

Geographical distribution, evaluation of risk of dengue and its relationship with the El Niño Southern Oscillation in an endemic region of Peru between 2004 and 2015

“…Our study identifies a peak of incidence in 2012, consistent with a study in Peru by Charette et al which describe a large outbreak of dengue in 2012 that caused more than 10,000 cases and 13 deaths in Ucayali, a region with borders to the East of the territory included in our study. It was suggested that the outbreak was triggered by the introduction of a new virus serotype (DENV-2 in Asia/America) [22]. Our observation indicates that this important outbreak was developed in the absence of the El Niño.…”

“…Our observation indicates that this important outbreak was developed in the absence of the El Niño. The introduction of a new serotype, increased frequency of travel, rapid urbanization and inadequate water management were determinant factors in the spread and transmission of the virus in that year [1, 22]. This suggests that in years when ENSO is absent there may be a high incidence of dengue virus infection, so the presence of this weather phenomenon alone would not be necessary or sufficient to produce an increase in the incidence of dengue in a determined endemic territory.…”

“…It is known that vector-borne disease are affected by climatic factors through ecological and biological processes that may favor their expansion [25] but apparently this is not enough to achieve a dramatic increase in the incidence of the disease as other factors would be, for example, the introduction of a new serotype in the case of dengue [22]. In addition to the climatic factor, other studies are investigating important co-factors for dengue transmission such as the entry rate of travelers and the mortality rate of dengue mosquitoes [26], in contrast some studies indicate that the average daily temperature, the variation of temperature and other meteorological variables such as rainfall are more important factors in the current distribution and incidence of dengue [8, 27].…”