identification of disease vector ticks in virginia presentations/david gaines tick... ·...

Identification of Identification of

Disease Vector Disease Vector

Ticks Ticks

in Virginiain VirginiaDavid N. Gaines, Ph.D.David N. Gaines, Ph.D.

Public Health EntomologistPublic Health Entomologist

VDHVDH--Office of EpidemiologyOffice of Epidemiology

EggsEggs

LarvaeLarvae

NymphsNymphs

Adult Adult

TicksTicks

Tick Life Cycle Tick Life Cycle -- After larvae hatch from eggs,After larvae hatch from eggs, ticks must ticks must

have one blood meal to transition to the next development stage.have one blood meal to transition to the next development stage.

NymphsNymphs

Adult Adult

TicksTicks

Blood Blood

MealMeal

Blood Blood

MealMeal

Blood Blood

MealMeal

There are 15 tick species found in Virginia, There are 15 tick species found in Virginia,

but only three of these species commonly but only three of these species commonly

bite people.bite people.

Lone star tickLone star tick

VeryVery

commoncommon

American dog tickAmerican dog tick

VeryVery

commoncommon

Black legged tick Black legged tick (formerly (formerly

known as the deer tick)known as the deer tick)

Uncommon or locally commonUncommon or locally common

Comparison of Human Biting Tick Species in VirginiaComparison of Human Biting Tick Species in Virginia

American dog tick American dog tick (only (only

adult ticks bite humans)adult ticks bite humans)

Blacklegged tick Blacklegged tick (adults (adults

and nymphs bite)and nymphs bite)1/8 inch

1/8 inch

Lone star tick Lone star tick (adults and (adults and

nymphs bite humans)nymphs bite humans)

1/8 inch

Tick identification is important because each Tick identification is important because each

different tick species carries itdifferent tick species carries it’’s own associated s own associated

tick borne diseases. tick borne diseases.

After a tick bite, identification of the tick will enable After a tick bite, identification of the tick will enable

the victim or a healthcare provider to predict what the victim or a healthcare provider to predict what

tick borne illness might result from the tick bite.tick borne illness might result from the tick bite.

Tick identification allows healthcare providers to target Tick identification allows healthcare providers to target

diagnostic efforts if the tick bite victim becomes ill. diagnostic efforts if the tick bite victim becomes ill.

Tick identification may also prevent needless Tick identification may also prevent needless

antibiotic usage prior to the onset of any illness.antibiotic usage prior to the onset of any illness.

VirginiaVirginia’’s Common Tick Vector Species and s Common Tick Vector Species and

their Associated their Associated Tick Borne DiseasesTick Borne Diseases

American dog tick.American dog tick.

1. Rocky Mountain spotted fever (RSMF)1. Rocky Mountain spotted fever (RSMF)

2. Tularemia2. Tularemia

Lone star tick.Lone star tick.

1. Human 1. Human monocyticmonocytic ehrlichiosisehrlichiosis (HME)(HME)

2. Southern tick associated rash illness 2. Southern tick associated rash illness

(STARI)(STARI)


VirginiaVirginia’’s Tick Vector Species and their s Tick Vector Species and their

Associated Associated Tick Borne DiseasesTick Borne Diseases

Blacklegged tick (a.k.a. deer tick)Blacklegged tick (a.k.a. deer tick)

1. Lyme disease1. Lyme disease

2. Human granulocytic 2. Human granulocytic AnaplasmosisAnaplasmosis (HGA)(HGA)

3. 3. BabesiosisBabesiosis


Tick IdentificationTick Identification

Tick identification is complicated by the fact that a tickTick identification is complicated by the fact that a tick’’s s

appearance varies with itappearance varies with it’’s development stage and sex. s development stage and sex.

Immature [larval and nymphal] ticks may look slightly Immature [larval and nymphal] ticks may look slightly

different than adult ticks of the same species. different than adult ticks of the same species.

Male and female ticks are indistinguishable in their Male and female ticks are indistinguishable in their

immature stages, but are obviously different from each immature stages, but are obviously different from each --

other in their adult stage. other in their adult stage.

The The scutumscutum is a hardened plate on the dorsal surface of a is a hardened plate on the dorsal surface of a

ticktick’’s body and is frequently used in tick identification. s body and is frequently used in tick identification.

The The scutumscutum is very useful for distinguishing is very useful for distinguishing American American

dog ticksdog ticks, , lone star tickslone star ticks, and , and blacklegged ticksblacklegged ticks from from

each other.each other.

ScutumScutum used to distinguish tick stage and sexused to distinguish tick stage and sex

Adult maleAdult male ticks ticks

are unable to are unable to

engorge because engorge because

the the scutumscutum will will

not expand.not expand.

1 mm1 mm

Female

Male

Nymph Larva

On On adult maleadult male

ticks, the ticks, the scutumscutum

covers the entire covers the entire

abdomen.abdomen.

The The ScutumScutum covers the front half of the abdomencovers the front half of the abdomen on on larvallarval and and

nymphalnymphal ticks of both sexes, and on ticks of both sexes, and on adult femaleadult female ticks. The ticks. The

part of the abdomen that is behind the part of the abdomen that is behind the scutumscutum can expand like can expand like

a balloon and fill up with blood when the tick is engorged.a balloon and fill up with blood when the tick is engorged.

1 mm1 mm

1 mm1 mm

1 mm1 mm

Use of Use of scutumscutum for tick species identificationfor tick species identification


Blacklegged tickBlacklegged tick


Female

Male

Female

Male

Female Male

ScutumScutum colorationcoloration on male ticks on male ticks

may aid in species may aid in species

identification.identification.

TheThe scutumscutum on female ticks varies on female ticks varies

in shape and color and is very in shape and color and is very

useful for species identification. useful for species identification.

Nymph

Nymph

It is important to be able to identify an It is important to be able to identify an

engorged tick that has fed on a person engorged tick that has fed on a person

because engorgement is often an indication because engorgement is often an indication

that the tick has fed long enough to transmit that the tick has fed long enough to transmit

a disease. a disease.

Minimum tick feeding times required for the transmission Minimum tick feeding times required for the transmission

of several tick borne diseasesof several tick borne diseases..

Rocky Mountain spotted fever Rocky Mountain spotted fever -- 4 4 toto 6 hours6 hours

Human Human monocyticmonocytic EhrlichiosisEhrlichiosis -- 24 24 toto 36 hours36 hours

Human granulocytic Human granulocytic AnaplasmosisAnaplasmosis -- 24 24 toto 36 hours36 hours

Lyme disease Lyme disease -- 36 36 toto 48 hours48 hours

Use of Use of scutumscutum for identification of engorged ticksfor identification of engorged ticks


Female

Coloration Coloration and and shape shape ofof scutumscutum will be the same on unwill be the same on un--engorgedengorged adult adult

female female ticks as on engorged ticks.ticks as on engorged ticks.

Legs Legs will have the same [reddish brown] color as the body.will have the same [reddish brown] color as the body.



TheThe scutumscutum will have the same will have the same semisemi--pentagonalpentagonal shapeshape on unon un--engorged engorged

nymphsnymphs and and adult femaleadult female ticks as on engorged ticks. ticks as on engorged ticks.

LegsLegs will have the same [yellowish will have the same [yellowish -- tan brown] color as the body. tan brown] color as the body.

ScutumScutum will have a posterior will have a posterior yellow spotyellow spot on on adult femaleadult female ticks andticks and will will

be be unun--adornedadorned on on nymphalnymphal ticks. ticks.

Blacklegged tickBlacklegged tick


ScutumScutum will be the same will be the same oval shapeoval shape and and dark brown colordark brown color on unon un--

engorged engorged nymphsnymphs and and adult femaleadult female ticks as on engorged ticks.ticks as on engorged ticks.

LegsLegs will be the same a will be the same a dark brown colordark brown color as the as the scutumscutum. .

0

100

200

300

400

500

600

700

800

900

1000

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

Year

Nu

mb

er

of

Case

s

Lyme disease

RMSF*

Ehrlichiosis

The most common tickThe most common tick--borne diseases seen in Virginia borne diseases seen in Virginia

over the last 18 years include: Lyme disease, Rocky over the last 18 years include: Lyme disease, Rocky

Mountain spotted fever (RMSF*), and Mountain spotted fever (RMSF*), and EhrlichiosisEhrlichiosis

Although Lyme endemic regions initially occurred in limited Although Lyme endemic regions initially occurred in limited

areas of the northeastern and north central U.S., these zoneareas of the northeastern and north central U.S., these zoness

of of endemicityendemicity have expanded.have expanded.

No RiskNo Risk

Low RiskLow Risk

Medium RiskMedium Risk

High RiskHigh Risk

LegendLegend

VirginiaVirginia

American Lyme Disease American Lyme Disease

Foundation (ALDFFoundation (ALDF)) Virginia is on the Virginia is on the

front line of this front line of this

expanding zone of expanding zone of

Lyme disease Lyme disease

endemicityendemicity..

And Lyme disease has become And Lyme disease has become

increasingly common in the increasingly common in the

states that have become states that have become

endemic .endemic .

Lyme Disease Cases in Maryland 1990 - 2007*

Graph by S.B. Wee, Maryland Department of Health & Mental Hygiene

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

*C

on

firm

ed

Lym

e D

ise

ase C

as

es

0

500

1000

1500

2000

2500

Lyme Disease Cases in Lyme Disease Cases in

Virginia 1990 Virginia 1990 -- 20072007*

Annual Rates of Confirmed Lyme Disease Cases per 100,000 Population

0

2

4

6

8

10

12

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

Year

Lym

e D

isease c

ases p

er

100,0

00

Po

pu

lati

on

Lyme disease in Virginia during a 19 year period Lyme disease in Virginia during a 19 year period

since the inception of case surveillance in 1989since the inception of case surveillance in 1989

2001 to 20062001 to 2006

Mean number of human Lyme disease cases per Mean number of human Lyme disease cases per

100,000 population for the period shown.100,000 population for the period shown.

0.1 to 4.9 5 to 9.9 10 to 24.9 25 to 49.9 50 to 99.9 100+

Confirmed cases per 100,000 population

20072007

Seasonal Occurrence of Lyme Disease in Virginia from 1990 to 2006

Mean Monthly Cases in the Period from 1990 to 2006

0

20

40

60

80

100

Month

Nu

mb

er

of

Co

nfi

rme

d L

ym

e C

as

es

19901991199219931994199519961997199819992000200120022003200420052006

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Month

Mo

nth

ly M

ea

n N

um

be

r o

f

Lym

e D

ise

ase

Ca

se

s

0

5

10

15

20

25

30

35

40

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Activity Period

for Nymphal Stage

Blacklegged Ticks

NYMPHAL TICK ABUNDANCENYMPHAL TICK ABUNDANCE

0

20

40

60

80

100

120

140

160

180

200

Ja

n.

Fe

b.

Ma

r.

Ap

r.

Ma

y

Ju

n.

Ju

l.

Au

g.

Se

p.

Oct.

No

v.

De

c.

Month

Nu

mb

er

of

Co

nfi

rme

d C

as

es Cases with Recorded

Onset Dates

Cases with Event

Dates Only

Seasonal pattern of VirginiaSeasonal pattern of Virginia’’s 959 Lyme disease cases s 959 Lyme disease cases

confirmed during the 2007 reporting year*. confirmed during the 2007 reporting year*.

** As of April 2008, a total of 945 cases were confirmed in 2007As of April 2008, a total of 945 cases were confirmed in 2007

VirginiaVirginia’’s 959 confirmed Lyme disease cases in 2007 s 959 confirmed Lyme disease cases in 2007

by sex and age group.by sex and age group.

0

20

40

60

80

100

120

Co

nfi

rmed

Lym

e D

ise

ase C

ase

s

Sex Unknown

Female [52.2%]

Male [47.6%]

Age Group

1-5

6-10

11-1

516

-20

21-2

526

-30

31-3

536

-40

41-4

546

-50

51-5

556

-60

61-6

566

-70

71-7

576

-80

81-8

586

-90

Unkn

ow

n

Geographic incidence of human Lyme disease cases Geographic incidence of human Lyme disease cases

in Virginia in 2008.in Virginia in 2008.

••To date, for the 2008 season in Virginia,To date, for the 2008 season in Virginia, a total of 882 human Lyme disease cases are a total of 882 human Lyme disease cases are notifiablenotifiable to CDCto CDC

(840 confirmed, 42 probable). Coordinates for home(840 confirmed, 42 probable). Coordinates for home residence or city/town of residence were availableresidence or city/town of residence were available

for 850 of these confirmed and probable Lyme cases.for 850 of these confirmed and probable Lyme cases.

Confirmed and Probable cases notifiable

to the CDC (850 total*)

Cases not yet confirmed or notifiable in

Virginia’s NEDSS database (88 total)

Prevention of Tick Borne DiseasesPrevention of Tick Borne Diseases

Wear repellents (DEET or Wear repellents (DEET or PermethrinPermethrin) on clothing ) on clothing

and shoes. and shoes.

Avoidance of Tick Habitats and Ticks Avoidance of Tick Habitats and Ticks

Thoroughly check yourself (clothing and body) after Thoroughly check yourself (clothing and body) after

spending time in tick habitats; use a full length mirror spending time in tick habitats; use a full length mirror

if possible.if possible.

Avoid prolonged periods in tick habitats (Avoid prolonged periods in tick habitats (humid forest humid forest

environments with dense undergrowth and/or heavy environments with dense undergrowth and/or heavy

leaf litterleaf litter; ; tall weeds along forest marginstall weeds along forest margins, , tree linestree lines, ,

forest trailsforest trails and and small forest clearingssmall forest clearings). ).

Wear light colored clothing and tuck pants legs under Wear light colored clothing and tuck pants legs under

socks.socks.

Wash and disinfect tick bite site. Wash and disinfect tick bite site.


Tick Removal Tick Removal

The transmission of tick borne diseases may require The transmission of tick borne diseases may require

hours or days of feeding time, so prompt tick removal hours or days of feeding time, so prompt tick removal

greatly reduces the chance of disease transmission.. greatly reduces the chance of disease transmission..

Carefully remove tick using tweezers. Carefully remove tick using tweezers.

Save tick in vial of alcohol for future identification. Save tick in vial of alcohol for future identification.

If you subsequently become ill, tick identification If you subsequently become ill, tick identification

might provide a clue as to the nature of your illnessmight provide a clue as to the nature of your illness. .


Tick Removal Tick Removal

Tick removal must be done carefully Tick removal must be done carefully

to prevent tick from regurgitating to prevent tick from regurgitating

into the wound or loosing tick mouth into the wound or loosing tick mouth

parts in your skin. parts in your skin.

Use pointed tweezers to grasp the Use pointed tweezers to grasp the

tick by the head; do not squeeze tick by the head; do not squeeze

its body. its body.

Pull slowly and steadily until the Pull slowly and steadily until the

tick releases; do not jerk or twist tick releases; do not jerk or twist

the tick. the tick.

AcknowledgementsAcknowledgements: :

2. VDH 2. VDH –– Division of Surveillance and Investigation Division of Surveillance and Investigation

Personnel (Les Branch, Personnel (Les Branch, AzizulAzizul Islam, Chris Novak).Islam, Chris Novak).

3. VDH 3. VDH –– Regional and District Epidemiologists.Regional and District Epidemiologists.

4. All local VDH and health department personnel involved 4. All local VDH and health department personnel involved

in reportable disease surveillance.in reportable disease surveillance.

1. Jennifer Halpaus 1. Jennifer Halpaus –– VDH Division of Environmental VDH Division of Environmental

EpidemiologyEpidemiology

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