An integrated approach to understanding knowledge, attitudes and practices surrounding dengue in emergent and endemic areas

Transcription

1 An integrated approach to understanding knowledge, attitudes and practices surrounding dengue in emergent and endemic areas Mary Hayden National Center for Atmospheric Research Boulder, Colorado, USA 5 December 2013 ICCS3

2 Collaborators A. Monaghan (PI), and L. Delle-Monache, D. Steinhoff, C. Uejio, P. Bieringer (NCAR) L. Eisen and S. Lozano-Fuentes, K. Kobylinski (Colorado State University) C. Welsh-Rodriguez, C. Ochoa, B. Tapia (University of Veracruz) E. Zielinski-Gutierrez (U.S. CDC) W. Crosson, D. Irwin, S. Estes, M. Estes (NASA/USRA) Veracruz-Puebla, Mexico study funded by NSF (CNH/EEID programs) with follow-on funding from NASA 2

3 Presentation Outline Introduction to dengue Temperature and precipitation in relation to Aedes aegypti Field study results - Ae. aegypti along an elevational transect in Mexico Next steps Adaptation

4 Dengue Fever The spread of disease vectors of dengue is one potential consequence of climate variability and urbanization Dengue Fever and Dengue Hemorrhagic Fever are caused by dengue viruses transmitted by Aedes mosquitoes Annually, 300 million people contract dengue infections worldwide 500,000 people develop severe dengue hemorrhagic fever every year No approved vaccine available Increasing number and severity of cases in the Americas Source: WHO DengueNet 4

5 Emergence of Dengue Environment Ae. aegypti DENV Human

6 Weather, Climate and Ae. aegypti

7 Aedes aegypti and Temperature Immature Development Thermally constrained (as well as by water/organic load); the higher the temperature, the quicker the immatures develop into adults Extrinsic Incubation Period Time needed for a newly infected female mosquito to become infectious Temperature dependent However, probability of transmitting virus also varies with how often the female bites a function of length of gonotrophic cycle Gonotrophic Cycle Time between ingesting a blood meal and oviposition; temperature dependent

8 Length of EIP and Gonotrophic Cycle vs. Temperature Adapted from Focks and Barrera 2006

9 Aedes aegypti and Precipitation Oviposits in artificial containers Containers can be rain-filled (tires; discarded items) or filled manually (potted plant bases; buckets; 55 gallon drums) Manually filled containers provide oviposition sites even in times of drought Even with reliable piped water, people store water

10 Veracruz-Puebla, Mexico

11 Framework for Aedes aegypti Study In-situ observations, Satellites, Models Weather and Climate Ae. aegypti Abundance Pupal & Larval Surveys

12 Main Transect in Study Region

13 Climate Data Collection Install 1-2 HOBO temperature/ humidity sensors in each community. Collect satellite-based rainfall data (CMORPH, TRMM) Supplement data with long-term records from available Mexican weather stations

14 Mosquito Sampling Collect immature mosquitoes and eggs in cities located along an elevation/climate transect from a low elevation at Veracruz (0-40m) to high elevation at Puebla (2150 m). Immature samples collected at 50 or more locations (households/cemeteries) in each of 12 communities during July September Total of ~600 households. In 2012, immatures collected from ~600 households in 4 upper elevation cities. Mosquitoes reared locally and shipped to CSU for identification.

15 Dengue Fever Risk in Mexico The Dengue Mosquito and Climate Diurnal Temperature Range ( o C) Diurnal Temp. Range Elevation Elevation above Sea Level (m) Proportion of Homes with Dengue Mosquito Ae. aegypti (Lozano et al. 2012; Lozano et al Eisen et al. 2013)

16 Cities, climate and Ae. aegypti along the transect in Mexico Mean elevation (m) Mean Tmax July (c) Mean Tmin Jan (c) Mean annual rainfall (mm) Est. proportion premises with Ae. aegypti Est. mean no. pupae per premise Veracruz , Cordoba , Orizaba 1, Rio Blanco 1, Cd. Mendoza 1, Acultzingo 1, Maltrata 1, Puebla 2,

17 Focus Groups, Household Survey Summer 2011, 2012 Sixteen FGs conducted in 4 communities along the transect FG information used for development of household survey undertaken in summer 2012 Water storage practices" Human-mosquito interactions/barriers such as screens" Cultural practices" Perception of dengue risk in community "

18 Core question areas Knowledge Mode of dengue transmission Different sites for oviposition Mosquito prevention strategies Attitudes Severity of dengue Risk of infection Mosquito burden Willingness to pay for control Practices Mosquito reduction Mosquito avoidance Health care seeking behavior

19 Outreach 1. Training high school students to collect mosquito and meteorological data and analyze the relationship between the two. ( participatory epidemiology ). 2. Hands-on training of undergraduate and graduate university students in field data collection protocol. Training Sessions Meteorological Data 3. Training of a postdoctoral researcher in climate-society-health issues. 4. SERVIR workshop held at the Universidad Veracruzana in March 2012 to train faculty/students in remote sensing Collected Aedes Eggs 5. Workshop held at Universidad Veracruzana in May 2013 with all participants

20 Future Directions

21 BIOMOD Results for Puebla (2100 m ASL) OBSERVED ΔTemp=+1 o C ΔRain=0% ΔTemp=+1 o C ΔRain=+15% ΔTemp=+1 o C Δrain=-15% A small temperature increase of 1 o C has the potential to double the number of premises harboring Ae. aegypti during the peak of the rainy season in the high altitude city of Puebla. A change at least this large is likely to occur within the next 50 years. The results are relatively insensitive to rainfall changes because water is already quite abundant during the rainy season. Unrealistically large changes in rainfall would be required to make a difference. We do not have a good sense of how rainfall may change in central Mexico. At lower altitude cities (not shown), we do not see the large projected changes in the % of premises with Ae. aegypti like we do here in Puebla, because these cities already lie well within the middle of the envelope of climatic suitability. So, it s the marginal cities where we are likely to see the largest changes.

22 Toward improving simulations of Ae. aegypti abundance: Modeling Ae. aegypti habitat suitability with WHATCH EM

23 Energy Balance Modeling in Breeding Containers QS = Q + Q Q Q Q Q Q SW LW LW H L C C W Q = Q + Q Q Q Q + Q + Q S SW LW LW H G C C C The heat storage (i.e., change in temperature) in the water container is equal to the balance of energy to/from the container SW: Shortwave radiation LW: Longwave radiation H: Sensible heat L: Latent heat G: Ground heat C: Conduction from container surfaces S: Heat storage Units: Power (W, energy per unit time) Sign convention: - Radiation terms: Positive into container - Other terms: Positive out of container

24 Energy Balance Model Example Field studies on different sized/colored buckets in shade, partial shade and full sun in Boulder, CO, Veracruz, MX and Orizaba, MX. HH collections of pupae and container characterization in summer 2013

25 Why model containers? Water insecurity promotes water storage o Need to target control of containers suitable for mosquito development People store water as an adaptation strategy in response to increased drought o Water harvesting popular in Australia, SW U.S. with unintended consequences -mosquitoes o Need to work with local gov t/distributors to ensure that containers are mosquito-proof and users are educated on proper usage/risks of mosquito-borne disease

26 Next Steps Better characterize weather conditions for the high elevation regions in Mexico Model association between weather variables and mosquito abundance Model impact of projected future change in temperature and rainfall on mosquito abundance Work with stakeholders (Ministries of Health/Civil Protection) to institute or enhance surveillance in areas at the margins of dengue transmission educate population on risk/prevention of dengue " reduce mosquito populations before they become established."

27 Thank you!