An evaluation of West Nile virus in WisconsinEffects of climate on environmental, wildlife, and human health

Johnny UelmenEpidemiology M.S. StudentEntomology M.S.

University of Iowa

My InterestsClimate Change, Infectious Diseases, Insect Vectors, Public Health, GIS, One-HealthIncorporating aspects of Entomology, Epidemiology, GIscience, and Climatology for predictive modeling

guardianlv.competcaregt.comEbola virus, CDC

Presentation Objectives

• Understand importance of interdisciplinary approach/collaborative effort to study infectious diseases and public health

• In order to understand (and eventually mitigate outbreaks):• View past West Nile disease prevalence in avian and wildlife cases

to human cases• Evaluate the potential for arboviral infectious disease transmission

influenced by the effects of climate change• Implement practical changes to reverse harmful anthropogenic

effects of environment, animal, and human health

West Nile Virus (WNv)• *Zoonotic **arbovirus from Flavivirus genus

• Not a “new” disease• First discovered in 1937 from 37 year old woman who fell ill, had

fever of 100.6°F near West Nile region of Northern Uganda

• Arrived in the U.S. in 1999 in New York• Most likely from Isr98 strain isolated from single goose (Israel 1998)1

• As of 2014: 41,762 cases leading to 1765 deaths• 2012: U.S. experienced one of the worst WNv epidemics in which 286 died• However, 70-80% infected people asymptomatic2

• No vaccine

*Zoonotic disease: disease that can be passed between animals and humans**Arbovirus: any group of viruses transmitted by mosquitoes, ticks, or other arthropod (Arthropod-borne virus)

West Nile Virus (WNv)• Preferred host is birds (“amplifying host”)• Many infected species contain high number of inoculum in blood &

tissues- = highly infectious• Birds that survive infection and have blood “cleared” of infection still able

to shed virus particles in tissues/skin for as long as 13 days6

• However, has ability to infect multiple hosts• 28 mammal, alligator, and amphibian species2

Human Symptoms• Common: headache, high fever, neck stiffness

• Serious: disorientation, coma, tremors, seizures, paralysis

Avian Symptoms• Initial: Emaciation, drowsiness, pinching off of

blood feathers • Advanced: clumsiness, unawareness of

surroundings, head tremors, severe tremors, seizures

Disease Transmission

• Incredibly “successful” disease• Ability to infect multiple hosts and vectors is atypical for Flavivirus

genus1,2

• Rapid spread across the U.S. (and the world)

• WNv transmittable via common water sources and close proximity to infected animals3

• But by far, greatest means of transmission is attributed to the

World’s Deadliest AnimalWhat is it???

The MOSQUITO! • Kills more humans than all other animals combined4

• Excellent insect vector• Capable of living 3-4 months (in lab) and 9 months when inactive

newslocker.com

The MOSQUITO! • Kills more humans than all other animals

combined4

• Excellent insect vector• Capable of living 3-4 months (in lab) and 9

months when inactive

• At least 43 mosquito species able to transmit WNv to ~160 bird species capable of amplifying disease in U.S. alone5

• Many of these bird species are migratory

• WNv is the most widespread arbovirus in the world6

• Found on every continent (except Antarctica)Culex species infectionlandscapes.org

During warm weather, life cycle completed in about 2 weeks

WNv in Wisconsin• Culex spp. primary mosquito vector• Capable of feeding on several hosts to satisfy one meal• Time between blood meals as early as 4-5 days7

• Detected in 70 of 72 counties

• Most common bird hosts:

fmel.ifas.ufl.edu

•2004 Southeast Wisconsin mammalian surveillance• Flavivirus antibody prevalence in 70 of

228 medium-sized mammals (31%)• 46 of Flavivirus antibodies were WNv

specific (20%)

uwyo.edu

Public & Environmental Health Link

• One Health: the collaborative effort of multiple disciplines to attain optimal health for people, animal and the environment

• Keystone species overall indicator of environmental health & disease susceptibility• May also serve as an “early warning” system for increased human disease risk8

• For example, WNv Birds cases usually spike in Spring & early Summer Many humans cases occur 1-2 months later in Mid-late Summer

“One Health”

onehealthinitiative.org

• Infectious disease “hotspots”• Example: Ribeiroia infections (on various amphibians)

more common along bird flyways8

• Increases in human populations expansion into new geographic areas increased contact with wild and domestic animals (e.g. Rabies & Salmonella infection opportunities more likely)

A Changing Climate…• Earth’s mean temperature has risen ~0.6°F10

• Since record keeping began in 1850s

• Warmest year on record = 201511

• Why & How?• Largely Anthropogenic forces

• Accumulation of greenhouse gases• Combustion of fossil fuels and other nonrenewable sources• CO2, CH4, NO2 among fastest gases accumulating

• Deforestation and land clearing (cattle grazing)• ~1 billion tons of carbon released per year12

calpactucb.blogspot.com

The Greenhouse Effect

Racing Extinction, Discovery Channel Clip (2 minutes)

Climate Change and Health• Most notable environmental risk is heat stress

• 1999-2009 there were 658 deaths/year13

• Vulnerable populations most affected (elderly especially)14

• Ironically, industrialized nations emit the most greenhouse gases, yet experience the least burden

truevaluemetrics.org

Oxfam

theworldreporter.com

CO2 emissions per capitaCO2 emissions by country

Climate Change and Health

truevaluemetrics.org

Oxfam

theworldreporter.com

CO2 emissions 1850-2011CO2 emissions by country

carbonmap.org

• Most notable environmental risk is heat stress• 1999-2009 there were 658 deaths/year13

• Vulnerable populations most affected (elderly especially)14

• Ironically, industrialized nations emit the most greenhouse gases, yet experience the least burden

Climate Change and Health

truevaluemetrics.org Oxfam

CO2 emissions by country

• Most notable environmental risk is heat stress• 1999-2009 there were 658 deaths/year13

• Vulnerable populations most affected (elderly especially)14

• Ironically, industrialized nations emit the most greenhouse gases, yet experience the least burden

Climate Change and Health• Climate change will most likely increase extreme weather events,

including droughts and periods of extreme heat

• In turn, wildfire risks will increase contributing to harmful particulates and decreasing air quality13

• However, climate change has profound effects on infectious diseases:

Waterborne Infectious Diseases• Drought and water scarcity Poor Sanitation

Practices (using same water source for bathing, irrigation, drinking)

• Excess Rainfall and flooding Increase in childhood GI illnesses13 (Cholera,

Campylobacter, Giardia, noroviruses, and Cryptosporidium)

Vectorborne Infectious Diseases• Increasing temperatures Increased

opportunities for insect range expansions (increased disease epidemics in previously un-

introduced regions)

• Drought and water scarcity Increase prevalence of arboviral infectious diseases (especially

encephalitides), as birds and other potential hosts are forced to congregate with higher proportions of infected mosquitos at fewer water sources15

MethodologyAll Wisconsin Data:

• Avian Cases• USGS NWHC

• 2462 serology tested Avian cases• At least 55 confirmed positive• ~150 (and counting) “sero-positive”

• Currently working on protocols establishing classification of “case” based on antibody titer levels

• Mammalian (non-equine) & Avian Cases• Wisconsin DNR

• At least 56 confirmed cases• Thousands serology tested that need to be sorted

• Wisconsin DOH

• Equine Cases• Wisconsin State Veterinary Diagnostic Lab

• 15 cases in last 10 years• Awaiting older cases from State Veterinarian’s office

Methodology• Confirmed human and wildlife cases are primary endpoints• Value in obtaining suspected (not necessarily tested for; based on behavior; etc.)

and low “sero-positive” cases for comprehensive surveillance & analyses purposes

West Nile Human Cases by State 1999-2014State 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Total

Wisconsin 0 0 0 52 17 12 17 21 13 8 1 2 3 57 21 6 230Total 62 21 66 4156 9862 2539 3000 4269 3630 1356 720 1021 712 5674 2469 2205 41762

Equine cases in Wisconsin (2003) (ArboNet provided)

MethodologyGeospatial Analysis

• Spatial patterns of diseases and public health can allows us to detect degree of associations among risk factors pertaining to where and why a particular event occurs

• A crucial step in understanding and predicting particular diseases• Leads to control measures and preventative measures

• Tobler’s First Law of Geography: “Everything is related to everything else, but near things are more related than far things”

Pennsylvania’s West Nile Virus Control Program

www.westnile.state.pa.us/surv_2006.htm

MethodologyGeospatial & Statistical Analyses

Geospatial analyses:• Average nearest neighbor: to detect if

clustering if present• Two-step clustering method: use of

continuous and categorical variables• Clusters cases by measuring log-

likelihood distance among them• “Hot Spot Analysis”

• Empirical Bayesian Kriging Method• Prediction with inverse distance interpolation

Statistical analyses:• Geospatial logical regression

co.henrico.va.us

Using ArcGIS to overlay & assess spatial components of disease Layers:

• Human & wildlife cases (confirmed, probable/suspect, sero-positive)• Drought index (by month)• Temperature index (by month)• Known and probable bird flyways and migratory routes through Wisconsin• Human population density

Examples of GIS layers(from project evaluating Malaria in Uganda)

Examples of GIS layers(from project evaluating Malaria in Uganda)

Examples of GIS layers(from project evaluating Malaria in Uganda)

• Empirical Bayesian Kriging (EBK)• Probabilistic Interpolation of Data

• Quantifies predictors from uncertainty of interpolated values

• EBK is advantageous model for prediction because it creates a spectrum of simulated semivariograms from which the observed process could be generated• Differs from classical Kriging models

that use only one model

What’s the Silver Bullet?

• NOT “direct” application of insecticides after outbreak has begun10

• Economically not feasible and environmentally harmful (long term)• Natural biological control programs

• Conservation of natural predators and keystone species• Ex: *Passerines (primary hosts) vs. Non-Passerine (non-competent hosts) birds in

“dilution effect”• Successful implementation directly linked to reduced risk of human WNv

transmission16

• Need to plan and implement environmentally conscious development projects to rebuild and maintain balanced ecosystems

We’re shooting ourselves in the foot!Many environmental issues are mediated through anthropogenic forces

*Passerines are a order of birds (containing more than half all bird species) known as “perching birds” with unique arrangements of their toes (3 forward and 1 back)

What’s the Silver Bullet?

• Excellent websites informing and promoting preventative measures• Fight the Bite (http://fightthebite.info/)

• Active surveillance websites• ArboNet – National Arboviral surveillance system managed by CDC

http://www.cdc.gov/westnile/resourcepages/survResources.html• Disease Maps from USGS http://diseasemaps.usgs.gov/index.html

• Up-to-date dynamic map viewer of many arboviral diseases

Collaboration & Communication = Prevention

*Passerines are a order of birds (containing more than half all bird species) known as “perching birds” with unique arrangements of their toes (3 forward and 1 back)

Limitations Of My Data• Limited to Wisconsin• Less cases (confirmed and suspected, overall)• Geographic precision limited to county level (privacy & confidentiality)• Limited time frame (2001-current)

• Reliable active surveillance data (wildlife) limited (2001-2008)• Passive surveillance since• Confounded with increasing human distributions (& less reported in

rural areas)

• Seropositive Positive• Recently recovered could provide false positives• Weak or moderate infections may have low inoculum levels deemed

non-infectious

• Collaboration is great, but data collection & use can be difficult!• Contributions and methods of data vary across agency• “Clearance” to show data

Future Directions• The BIGGER picture = Global Health = One Health• Evaluating ongoing diseases in across large, targeted regions of the world• Implement environmental algorithms for evaluation in respective geographic locations

• Current & past outbreaks• ZIKA!• Malaria• Dengue• Lyme Disease

• Evaluate and predict the susceptibility of current/future outbreaks in vulnerable populations

• For Ph.D. (Environment & Resources, Nelson Institute), incorporating global health components• Pursuing collaboration in Thailand (Summer 2016) & East Africa (???)

Acknowledgments• My advisors:• Dr. Charles Brokopp, Director

State Laboratory of Hygiene• Dr. Jonathan Patz, Director

Global Health Institute

• Wisconsin Department of Health• Zip Johnson

• Wisconsin Department of Natural Resources• Nancy Businga

• USGS National Wildlife Health Center (NWHC)• Barb Bodenstein• Kim Miller• Emily Lankau• Jenny Chipault• LeAnn White• Karen Cunningham

• Wisconsin Veterinary Diagnostic Laboratory• Keith Poulsen

References1. McLean, R.G. 2002. West Nile Virus: A Threat to North American Avian Species. Transactions of the sixty-seventh North American

Wildlife and Natural Resources Conference 1: 62-74.

2. CDC 2015, http://www.cdc.gov/westnile/symptoms/index.html

3. USGS 2000

4. Hughes, T., Irwin, P., Hofmeister, E., and Paskewitz, S.M. 2010. Occurrence of Avian Plasmodium and West Nile Virus in Culex species in Wisconsin. Journal of the American Mosquito Control Association 26: 24-31.

5. Dusek, R.J., McLean, R.G., Kramer, L.D., Ubico, S.R., Dupuis II, A.P., Ebel, G.D., and Guptill, S.C. 2009. Prevalence of West Nile Virus in Migratory Birds during Spring and Fall Migration. American Journal of Tropical Medicine Hygiene 81: 1151-1158.

6. Marra P.P., Griffing, S., Caffrey, C., Marm Kilpatrick, A., McLean, R., Brand, C., Saito, E., Dupuis, A.P., Kramer, L, and Novak, R. 2004. West Nile Virus and Wildlife. American Institute of Biological Sciences 54: 393-402.

7. Haines, A. & Patz, J.A. 2004. Health Effects of Climate Change. Journal of the American Medical Association 291: 99-103.

8. Venton, D. 2015. News Feature: Many species, one health. PNAS 112: 1647-1649. www.pnas.org/cgi/doi/10.1073/pnas.1423578112.

9. Guptill, S.C., Julian, K.G., Campbell, G.L., Price, S.D., and Marfin, A.A. 2003. Early-season avian deaths from West Nile Virus as warnings of human infection. Emerging Infectious Diseases 9: 483-484.

10. EPA 2014

11. Carlton, J. West Nile Virus Hits California – Drought Triggers Skyrocketing Number of Cases – 238 in Humans – So Far This Year. The Wall Street Journal: New York, N.Y. p.A3. September 11, 2014.

12. CDC 2012

13. Patz, J.A., Frumkin, H., Holloway, T., Vimont, D.J., and Haines, A. 2014. Climate Change Challenges and Opportunities for Global Health. Journal of the American Journal Society 312: 1565-1580.

14. Handmer et al. 2012

15. NOAA 2015

16. Shuman, E.K. 2010. Global Climate Change and Infectious Disease. The New England Journal of Medicine 362: 1061-1063.

17. Ezenwa et al. 2000