CAPT Michael E. Herring, REHS, MPHSenior Environmental Health Scientist

CDC National Center for Environmental Health

Environmental Health Services Branch

Vector-Borne Diseases

National Center for Environmental Health

Division of Emergency and Environmental Health Services

The Critical Role of Environmental Healthin Vector Control and Disease Prevention

Brain Teaser –

What percentage of all diseases known to affect human-kind

throughout history are zoonotic (of animal origin) and often transmitted

by a vector?

60 Percent!

Brain Teaser – 2

What percentage of all new or emerging diseases that threaten

human health today are zoonotic or vector-borne illnesses?

75 Percent!

What animals are responsible for more human illness and death than any other group of mammals?

Rats and Mice

How many human diseases

can be transmitted by

rodents?

61

Based on CDC projections, how many West Nile virus infections have occurred

in the U.S. since the virus was first identified here in 1999?

1.8 Million!!!

What disease vector ranks #1 in pathogen diversity?

Ticks

What type of tick is the likely the most common in the

world?

The Brown Dog TickRhipicephalus sanguineus

VectorTransmitters of disease-causing

organisms that carry a pathogen from one host to

another

Vector-Borne Disease TransmissionBiological

• Most significant mode of transmission- Arthropod ingests a pathogen while taking a blood meal from an infected host - Pathogen multiplies within the arthropod (reservoir)- Pathogen is transmitted to another host when

arthropod takes another blood meal

Mechanical• Vector physically carries pathogens from

one place or host to another, usually on body parts or through the gastrointestinal tract

Vector-Borne Disease Transmission• Transovarian transmission -

Infectious agent is passed vertically to succeeding generations

• Transstadial transmission – infectious agent is passed from one stage of life cycle to another, as nymph to adult

Emergence/Resurgence of Vector-Borne Diseases

• Pesticide resistance• Decreased resources for surveillance,

prevention and control• Deterioration of public health infrastructure• Unprecedented population growth• Uncontrolled urbanization• Changes in agricultural practices• Deforestation• Increased travel

*Encyclopedia of Public Health

What’s going on out there?

Mosquito-Borne Disease

West Nile Virus Total Cases in U.S. 1999-2009

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

10

100

1000

10000

Reported Human Cases ReportedAverage = 2891/yr; range = 21-

9862

Nu

mb

er

of

Cases (

log

scale

)

Year

Reported WNND Cases, United States, 1999-2009*

YearTotal

WNND

1999-

2002

3,088

2003 2,866

2004 1,148

2005 1,309

2006 1,495

2007 1,227

2008 689

2009*

366

Total

12,188

* Reported as of 2/4/2010

12,188 WNND Cases

X 28 WNF/WNND

~341,000 WNF Cases12,188 WNND Cases

x 140 infections/WNND

~ 1.7 Million Infections

WN Fever ~17%

Asymptomatic ~82%

WNV: The “Iceberg” WNND <1%

1 WNND : 28 WNF1 WNND : 140 Total Infections

WN LAC SLE EEE POW WEE 0

200

400

600

800

1000

1200 1108

8919 8 1.5 0.01

Avg

. N

um

ber

of

Cases

Arboviral Nuroinvasive Disease

Annual average Cases 1999-2009 in the USA

119 Cases per year combined

WNV: Long-Term Outcomes• WN Encephalitis and WN Fever

– Persistent disabling neurologic sequelae common

– Tremors, movement disorders, cognitive problems in >50%

– 8 published studies show complaints frequently persist >1 year post infection (Some > 3 years)

– Fatigue, pain, subjective memory / concentration problems

– Higher all-cause mortality rates >1 year post-infection

*# Sejvar et al., J Neuropsychol 2008; ^Greenberg et al., EID 2005;

>300 Bird Species Killed by WNV Since 1999

American Crow Carolina Wren Gray Catbird Northern Goshawk Scissor-tailed FlycatcherAmerican Goldfinch Cedar Waxwing Gray-cheeked Thrush Northern Harrier Sharp-shinned HawkAmerican Kestrel Chilean Flamingo Great Black-backed Gull Northern Mockingbird Short-eared OwlAmerican Robin Chimney Swift Great Blue Heron Northern Parula Snowy OwlAmerican White Pelican Cockatiel Great Egret Northern Saw-whet Owl Song SparrowBald Eagle Cockatoo Great Horned Owl Northern Waterthrush Steller's JayBaltimore Oriole Common Grackle Great-tailed Grackle Osprey Swainson's HawkBarn Owl Common Ground-Dove Green Heron Ovenbird Swainson's ThrushBarn Swallow Common Loon Guanay Cormorant Pied-billed Grebe Swallow-tailed KiteBarred Owl Common Nighthawk Harris' Hawk Prairie Falcon Traill's FlycatcherBelted Kingfisher Common Raven Hermit Thrush Purple Finch Tufted TitmouseBlack Skimmer Common Yellowthroat Herring Gull Purple Martin Tundra SwanBlack Vulture Cooper's Hawk Hooded Warbler Red-crowned Parrot Turkey VultureBlack-billed Magpie Dickcissel House Finch Red-eyed Vireo Varied TitBlack-capped Chickadee Domestic Chicken House Sparrow Red-headed Woodpecker VeeryBlack-crowned Night Heron Double-crested Cormorant Impeyan Pheasant Red-shouldered Hawk Virginia RailBlackpoll Warbler Downy Woodpecker Kentucky Warbler Red-tailed Hawk Warbling VireoBlack-throated Blue Warbler Eastern Bluebird Killdeer Red-winged Blackbird Western Scrub-JayBlack-whiskered Vireo Eastern Kingbird Laughing Gull Ring-billed Gull White-breasted NuthatchBlue Jay Eastern Phoebe Least Bittern Ring-necked Pheasant White-crowned PigeonBlythe's Tragopan Eastern Screech-Owl Loggerhead Shrike Rock Dove White-winged DoveBoat-tailed Grackle Eastern Towhee Lorikeet species Rose-breasted Grosbeak Wild TurkeyBrewer's Blackbird Emu Macaw Rough-legged Hawk Winter WrenBroad-winged Hawk Eurasian Collared-Dove Mallard Ruby-throated Hummingbird Wood DuckBronze-winged Duck Eurasian Wigeon Merlin Ruddy Duck Wood ThrushBrown Thrasher European Goldfinch Mississippi Kite Ruddy Turnstone Yellow WarblerBrown-headed Cowbird European Starling Mourning Dove Ruffed Grouse Yellow-bellied SapsuckerBudgerigar Evening Grosbeak Mute Swan Rusty Blackbird Yellow-billed CuckooCanada Goose Field Sparrow Nashville Warbler Sandhill Crane Yellow-crowned Night-HeronCanada Warbler Fish Crow Northern Bobwhite Savannah Sparrow Yellow-rumped WarblerCanvasback Fox Sparrow Northern Cardinal Scarlet Ibis Zebra FinchCarolina Chickadee Golden Eagle

Mammals killed by WNV in the USA

• Horse• Squirrel• Dog• Cat• Sheep

• Domestic rabbit• Eastern Chipmunk• Striped Skunk• Bat• Raccoon

Dengue• Dengue is transmitted between people by

Aedes aegypti and Aedes albopictus• More than one-third of the world’s

population living in areas at risk for transmission

• Over 100 million people are infected yearly• No vaccine and no specific treatment.

Dengue• Dengue fever - high fever, severe

headache, severe pain behind the eyes, joint pain, muscle and bone pain (“break-bone fever), rash, and mild bleeding

• Dengue hemorrhagic fever – 2 to 7 days of high fever followed by persistent vomiting, severe abdominal pain and difficulty breathing. Next phase is a 24- to 48-hour period when capillaries become “leaky” leading to pleural effusions. May lead to circulatory system failure and shock, followed by death, if not treated.

Tick-Borne Disease

Lyme Disease• Caused by the bacterium Borrelia burgdorferi • Transmited to humans through the bite of• infected blacklegged ticks• The deer tick, (Ixodes scapularis) spreads the

disease in the northeastern, mid-Atlantic, and north-central United States, and the western blacklegged tick (Ixodes pacificus) spreads the disease on the Pacific Coast.

• Symptoms - fever, headache, fatigue, and a characteristic skin rash called erythema migrans (70 - 80% of infections)

• If left untreated, infection can spread to joints, the heart, and the nervous system

• #1 reportable vector-borne disease in the U.S. and the #5 most reported disease overall.

Reported Cases of Lyme Disease by Year, United States, 1995-

2009

Reported Cases of Lyme DiseaseUnited States, 2009

Range of Ixodes pacificus(Western black-legged tick)

Rocky MountainSpotted Fever

• Caused by the bacterium Rickettsia rickettsii• Transmitted in the U.S. by the American dog tick

(Dermacentor variabilis, Rocky Mountain wood tick (Dermacentor andersoni), Lone Star tick (Amblyomma americanum) and brown dog tick (Rhipicephalus sanguineus)

• Symptoms - fever, headache, abdominal pain, vomiting, and muscle pain. A rash may develop, but is often absent in the first few days, and in some patients, never develops

• RMSF is a serious illness that can be fatal in the first eight days of symptoms if not treated correctly (doxycycline within 5 days)

Tularemia• Caused by the bacterium Francisella tularensis. • Transmitted to humans by the dog tick

(Dermacentor variabilis), the wood tick (Dermacentor andersoni), and the lone star tick (Amblyomma americanum).

• Deer flies (Chrysops spp.) have been shown to transmit tularemia in the western U.S.

• Highly infectious. A small number (10-50 or so organisms) can cause disease.

• Potential bio-terror weapon. Commonly occurs in nature. People who inhale an infectious aerosol would experience severe respiratory illness, including life-threatening pneumonia and systemic infection.

Tularemia

• Ulceroglandular - Occurs following a tick or deer fly bite or after handing of an infected animal. Skin ulcer appears where the organism entered the body (most common form).

• Glandular - Similar to ulceroglandular but without an ulcer.

• Oculoglandular - Bacteria enter through the eye. Can occur when touching the eyes while butchering an infected animal.

• Oropharyngeal - From eating or drinking contaminated food or water (sore throat, mouth ulcers, tonsillitis, and swelling of lymph glands in the neck.)

• Pneumonic - Most serious form. Symptoms include cough, chest pain, and difficulty breathing. Results from breathing dusts or aerosols containing the organism.

Reported cases of Tularemia, United States 2001-2010

Flea-Borne Disease

Plague• Caused by the bacterium Yersinia pestis.• Usually transmitted by the bite of an

infected rodent flea or by handling an infected animal

• The last U.S. urban plague epidemic occurred in Los Angeles in 1924-25

• Most human cases in the United States occur in two regions: 1) northern New Mexico, northern Arizona, and southern Colorado; and 2) California, southern Oregon, and far western Nevada

Plague• Bubonic plague: enlarged, tender lymph

nodes, fever, chills and prostration (total exhaustion/collapse)

• Septicemic plague: fever, chills, prostration, abdominal pain, shock and bleeding into skin and other organs

• Pneumonic plague: fever, chills, cough and difficulty breathing; rapid shock and death if not treated early

RATS!!!

ECONOMIC IMPORTANCE• Rats in the human environment

cause enormous economic loss- Consume and contaminate vast

quantities of food- Cause fires by gnawing the

insulation from electric wires

• Commensal rodents cost billions of dollars each year in the United States.

- Internal destruction to computers and other sensitive equipment

- Structural damage to homes and businesses

Human Health Impact

RODENT-BORNE DISEASES

• Rats and mice spread diseases in two distinct ways.– Directly - by contamination of food, water and

air with their urine and feces– Indirectly – by way of rodent fleas, ticks and

mites Direct Indirect

• Rat bite fever Plague• Salmonellosis Murine typhus• Leptospirosis Scrub typhus• Hantavirus Tularemia

Bed Bugs• Resurgence of a pest health

departments have not dealt with in over 50 years.

Why are they back?Greater international and domestic travelLack of knowledge regarding control of bed bugs due to their prolonged absenceIncreased resistance to available pesticidesThe continuing decline or elimination of effective vector/pest control programs at state and local public health agencies.

Photo courtesy of Dr. Harold Harlan, Armed Forces Pest Management Board Image Library (http://www.afpmb.org)

2011 NPMA Bed Bug Survey2010 2011

College dorms 35 54Hotels/motels 67 80Nursing homes 25 46Office buildings 18 38Schools /day care centers 10 36Hospitals 12 31Transportation (train/bus/taxi) 9 18Movie theaters 5 17

• Survey respondents also report finding bed bugs in retail stores, laundromats, libraries, restaurants and airplanes.

State Public Health Vector Control Conference:

Workforce and Disease Priorities NeedsAssessment Summary

2007

State Public Health Vector Control Conference:

Workforce and Disease Priorities NeedsAssessment Summary

********************************************Seventy-four percent of SPHVCC

survey respondents reported they didnot have a sufficient number of

public health workers to effectivelystaff their vector control units.

*******************************************

State Public Health Vector Control Conference:

Workforce and Disease Priorities Needs

Assessment Summary• 66% of respondents said they lacked capacity for field-based surveillance and control teams• 41% lacked medical entomologists• 41% lacked specialists in public health promotion and education• 38% lacked tick control and disease specialists• 25% lacked epidemiological surveillance capacity

State Public Health Vector Control Conference:

Workforce and Disease Priorities NeedsAssessment Summary

***************************************Eighty percent (80%) of respondents said that their agencies had undertaken no activity in

regards to preparing for climate change and its effect on vector-borne diseases.

********************************************(Note: The remaining 20% stated their agencies had

undertaken “limited” activities.)

So what is CDC doing to confront these challenges?

CDC Activities Collaboration (e.g. Federal Bed Bug

Work Group, Public Health Pesticide Consortium)

Education/information dissemination Environmental health workforce

development/training Resource for basic entomology,

pesticide resistance and IPM 

Integrated Pest Management

Integrated Pest Management (IPM) is the coordinated use of pest and environmental information with available pest control methods to prevent unacceptable levels of pest damage by the most economical means and with the least possible hazard to people, property, and the environment.

Biology and Control of Vectors and Public Health Pests: The Importance of IPM

Biology and Control of Vectors and Public Health Pests

• Training focal areas – – Integrated Pest Management (IPM)– Vectorborne Diseases– Rodent Control– Mosquito Control– Tick Control– Bed Bug Control and Interactive Inspection– Bio-terror Agents– Pesticides/”Green” Pest Control– Housing and Lodging Pests– Food Service Pests (including “kitchen crawls”)– School IPM– Global Climate Change

• Biology and Control of Insects and Rodents

• Biology and Control of Vectors and Public Health Pests: IPM

• Environmental Health Training in Emergency Response (EHTER)

• Environmental Health Performance Standards

www.nehacert.orgCDC Sponsored Programs

Environmental Public Health Online Courses (EPHOC)

http://www.southcentralpartnership.org/ephoc

- General Environmental Health - Radiation Protection- Statutes and Regulations - Occupational Safety and Health- Food Protection - Air Quality/Environmental Noise- Potable Water - Housing Safety and Sanitation- Wastewater - Institutions and Licensed- Solid and Hazardous Waste Establishments- Hazardous Materials - Swimming Pools and -Zoonoses, Vectors and Pests Recreational Facilities-- Disaster Sanitation

Training/Reference Material

www.cdc.gov/nceh/ehs/default.htm