Arthropoda 7 Ticks Mites

7/28/2019 Arthropoda 7 Ticks Mites

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Phylum Arthropoda - Chapter 33

The Phylum Arthropoda is the most successful of all phyla.

It surpasses all other phyla in:

1. ______________________________________________

_________________________________________________

2. _______________________________________________

_________________________________________________


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Phylum Arthropoda

Arthropods are important to parasitologists as:

1. _____________________________________- mites (scabies)

2. _____________________________________ - grain beetles

(Hymenolepis), fleas (Dipylidium), copepods (Diphyllobothrium,Dracunculus)

3. ___________________- mosquitoes (malaria, filarial worms),

blackflies (river blindness), tsetse flies (African trypanosomiasis),

reduviid bugs (Chagas Disease), etc.


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Phylum Arthropoda

Arthropod intermediate hosts and vectors serve to transmit

1.

2.

3.

4


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Characteristics of the Phylum Arthropoda

1. __________________________

2. __________________________- body consists of segments(metameres) fused into functional units

3. ___________________________________ - allow for greatmovement

4. ___________________________________- composed ofchitin; growth involves molting

5. well-developed nervous system, digestive system, &excretory system


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Characteristics of the Phylum Arthropoda

6. ___________________________________ - coelom servesas a hemocoel tocollect blood from the tissues

7. respiratory system developed for gas exchange

8. most arthropods are ________________________ -copulatory appendages present


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Groups of Arthropods

Three major groups of importance to parasitologists:

______________________________ - ectoparasites of fish;

intermediate hosts

______________________________ - ticks and mites

_____________________________- lice, fleas, bugs, and flies


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Ticks - Chapter 40

Taxonomy: Phylum ArthropodaClass Arachnida

Order Acari (=Acarina)

Important as ectoparasites and as vectors of several human

diseases.

Body consists of 2 regions:

1. Capitulum -

______________________________

2. Idiosoma - contains

_________________________


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Capitulum of a Tick

Capitulum consists of:

1. pedipalps - _________________________________________

2. chelicerae - _________________________________________

3. hypostome - ________________________________________

4. mouth - between chelicerae and hypostome

5. basis capituli - ______________________________________


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Capitulum of a Tick

Tick capitulum SEM of tick hyposome showing teeth; this is

why ticks are so hard to pull out!


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Idiosoma of a Tick

Contains all internal organs

Nymphs and adults have 4 pairs oflegs; larvae with 3 pairs of legs.

Dorsally, a _____________________________________ is present

covers entire dorsum in males

covers anterior part only in females

____________________________________invaginations of the posterior

margin - present in some, lacking in others (taxonomic character)


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Characteristics of Ticks

1. ______________________________________

2. __________________________ exposed and with teeth

3. 4 life cycle stages - __________________

__________________ (3 pr. legs)__________________ (4 pr. legs)

__________________ (4 pr. legs)


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Characteristics of Ticks

4. both males and females feed on blood

- copulation occurs on host

- female __________________________and drops

to ground to lay eggs


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2 Families of Ticks

Family Ixodidae - hard ticks

- hard idiosoma

- scutum present dorsally on idiosoma

- capitulum is terminal

Family Argasidae - soft ticks (discuss later)


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Ticks in Wisconsin


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Dermacentor variabil is

Common names: _______________________________________

Preferred host is the_________________ but the tick will feedon almost any large carnivore and humans

Common throughout eastern and central U.S. including Wisconsin


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Morphology ofDermacentor var iabil is

Male - ornate white-mottled scutum covers entire idiosoma

Female - scutum occurs on anterior part of idiosoma

- can reach size of pea when engorged with blood prior to egg-laying

Both sexes have 11 festoons at the posterior end


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Morphology ofDermacentor var iabil is

Unengorged and engorged female


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Life Cycle ofDermacentor var iabi l is

1. Adults prefer to

feed on dogs but willattach and feed on

any large mammalincluding humans.

2. Engorged female

drops off host and

lays 4,000 to 6,500eggs on ground.


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3. Eggs hatch in a

month into small six-legged larvae that

attach and feed on

_________________

_________________

_________________

In a week, they drop

off and molt to the

_________________stage.


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4. The 8-legged nymphs

attach and feed on_____________________

and in another week, dropoff and molt to adults.

5. Adults occur in grassy

areas where they quest

until a large mammal

comes by.

Adults may live for 2

years.


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Tick crawls to tip ofvegetation near a path and

extends first pair of legs,

hoping to attach to host when

it contacts the tick as it walks

by on the path.

Engorged female releasing eggs on soil

Egg Laying Tick Questing


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Importance ofDermacentor variabi l is

1. Heavy infestations on mammals can cause ____________________

in the host.

2. __________________________________ is caused by female tick

attached to base of skull (on back of neck).

- Toxic secretions produced by the feeding tick cause anascending paralysis - legs are first involved; if paralysis

ascends to respiratory muscles, fatality could occur.

- Numerous cases reported in the 1960's (long hair was in style)

- Complete recovery by removing the tick

3. Principle vector of _____________________________________(will discuss tick diseases later)


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Dermacentor andersoni

Occurs in western U.S.

Biology is similar to that ofD. variabilis - causes same problems

Important as vector of tick-borne typhus in Rocky Mountain states


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I xodes scapularis = I xodes dammini

Most important tick in Wisconsin and

Minnesota.

Called the _____________________

as the preferred host is the

______________________________

But the tick will feed on any large

mammal including dogs, horses, cattle,

pigs, and humans.

Originally called the bear tick, but this

name is incorrect, as common name

should refer to the preferred host


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Distribution ofI xodes scapularis = I xodes dammini


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Morphology ofI xodes scapularis

Adult ticks are much smaller that dog ticks.

Major identifying characteristic is the presence of an__________________________________ in front of the anus. This

can easily been seen under the microscope.

These ticks lack festoons.

Anal groove


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Male - scutum covering idiosoma is uniform brown color.

Female - scutum is small and red to brown in color. The remainder of theidiosoma is reddish to cream colored. Females engorge prior to egg-laying.


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male

female

capitulum


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2 Year Life Cycle ofI xodes scapularis


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Importance ofI xodes scapularis

1. Primary vector of

___________________________________________________

2. Vector of human babesiosis caused by

_____________________________________

3. Vector of Human Granulocytic Ehrlichiosis


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Amblyomma americanum

Common name is ______________________________________

Adults occur on many mammals in southern U.S. - occasionally foundin Wisconsin.


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Morphology: recognized by round idiosoma and elongate capitulum

Female is easily identified by bright silver spot on scutum


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Comparison of females ofAmblyomma andDermacentor- note the

rounder idiosoma onAmblyomma and silver spot on scutum


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Life Cycle: larvae and nymphs generally

occur on _____________

adults on mammals

All stages will bite humans when available

Importance - vector of

_____________________________________

_____________________________________

in Texas and other southern states


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Rhipicephalus sanguineus

Common name__________________________________

- all stages (larvae, nymphs, & adults) arefound on dogs in North America

- found occasionally on Wisconsin dogs(not as common asDermacentor)

Morphology: small brownish tick with

"spurs" on basis capituli and festoons at

posterior margin

Importance - vector of__________________________________

Spur on basis capituli


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Family Argasidae - soft ticks

Soft ticks are characterized by:

1. subterminal capitulum

2. no scutum

3. idiosoma is thick, leathery; often highly irregular.

These ticks feed repeatedly on their hosts but rest away from their hostswhen not feeding. They rest in nests and burrows.


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Argas persicus

Common name ___________________

Parasites on _____________________

Recognized by its flat bodyseen inside view of specimens in dish

Can build up huge populations in a

henhouse causing severe anemia in

chickens. May kill chickens.

Will bite humans if available i.e.vagabond spending night

in abandoned henhouse


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Ornithodorosspp.

Some 90 species feed on a variety of

mammals including humans.

One species occurs in Wisconsin -

Orni thodoros kelleyi- common name is

________________________________

Other species are common in the western

states.

Identified by rough idiosoma.

Bite is highly toxic and painful.


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Tick-Borne Diseases

Tick-borne typhus (= Rocky Mountain Spotted Fever)Vectored by Dermacentor variabi l is, D. andersoni, & Amblyomma americanum

Disease occurs primarily along the eastern coast and southcentral U.S. (disease was

first described in Idaho and named there as Rocky Mountain Spotted Fever) - but

since most cases occur in eastern and southcentral U.S., the disease has beenrenamed tick-borne typhus


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Tick-Borne Typhus

Caused by the _______________Rickettsia r ickettsiiDisease - body rash, high

fever, and severe headache.

Treated with

___________________________

Both male and female ticks can

transmit the disease.

Average of 600 cases of tick-borne typhusin the U.S. each year- 20-30 cases are fatal.

Two cases were reported in Wisconsin in

1987.


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Lyme Disease

Lyme disease was first reported in 1969 in grouse hunter from

Medford, Wisconsin.

Disease was not named, however, until 1975 when a largeoutbreak of arthritis occurred in children in Lyme, Connecticut


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Vectors of Lyme Disease

3 species of ticks have been identified as vectors:

Principle vector is I xodes scapularis- vector of cases in

New England states and Wisconsin and Minnesota

I xodes pacif icus(black-legged tick) is vector in Pacificcoast states

Amblyomma americanum and I xodes scapulari sarevectors in Texas and other southern states


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Lyme Disease in U.S.


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Cases of Lyme Disease

We have been averaging _______________cases of Lyme Disease each year

- only _____ cases resulted in fatalities due to heart failure

- average of ____________cases/year in Wisconsin

Number cases of Lyme Disease in U.S.


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Lyme Disease in Wisconsin

Lyme Disease was first

reported in Wisconsinin 1979

Since late 1980s, we

have been averaging

about 400 cases of

Lyme Disease per yearin Wisconsin but

sudden increase in 2006

to 1456 cases


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Causative Agent of Lyme Disease

In 1982, the causative agent of Lyme disease was discovered -

a ___________________________________________ namedBorrel ia burgdorfer i

Named after Willy Burgdorfer who first identified spirochaete in

the deer tick.

Spirochaete appears as

a short helix

Motile

Gram negative

Multiply in the midgut

of the deer tick


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Reservoirs of Lyme Disease

Important reservoir hosts of

Lyme disease are_________________________

_________________________

These hosts do not shown

any symptoms of thedisease.

They serve to infect deer

tick__________________

___________________________ are also reservoirs of Lyme

disease but are not affected by the spirochaete.

O f L Di


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Onset of Lyme Disease

Most cases of Lyme Disease are reported in summer - the

____________________________ are the source of these infections;

____________________________ vector disease in fall.

3 S f P h l f L Di


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3 Stages of Pathology of Lyme Disease

1. First stage occurs 3-30 daysafter tick bite.

In 50% of cases involving

children and in 70% of cases in

adults, a red rash around the

bite occurs - called

______________________________________________________

It commonly reaches a diameter

of 6".

Other symptomsare_______________________:

headache, fever, stiff neck,

nausea, fatigue, and aching

muscles and joints.

3 St f P th l f L Di


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2. Stage 2 occurs weeks to months after

initial exposure.

Bacteria multiply rapidly and invade thecirculatory and nervous systems.

Circulatory disorders - irregular beat,bradycardia

Neurological disorders - facial paralysis

called ____________________________,

weakness in the limbs, and memorydifficulty.

3 fatal cases resulted from cardiac failure.

Transplacental transmission of the

bacteria to fetus during this time can resultin heart defects and other birth defects.

3 St f P th l f L Di


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3. Stage 3 occurs a year after the initial bite.

The most common symptom in stage 3 Lyme disease are intermittantattacks of _______________________________. The knee iscommonly affected.

Neurological disorders such as profound fatigue, impaired

concentration and loss of short-term memory, and personalitychanges can occur.


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Timing of Pathology of Lyme Disease

Di i f L Di


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Diagnosis of Lyme Disease

DIAGNOSIS - identification of clinical symptoms associated with

tick bite.

Immunological tests determine presence of Lyme antibodies:

1. ELISA

2. IFA - Immunofluorescent assay

Problem:

T t t f L Di


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Treatment of Lyme Disease

1. _____________________________________. Studies indicate

that the tick does transmit the bacteria until at least 24 hours afterattachment.

- Tick should be removed with fine forceps to insure complete

removal of the hypostome.

T t t f L Di


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Treatment of Lyme Disease

2. Treatment with ___________________________________-

tetracycline, amoxicillin, azithromycin, and doxycycline are used totreat early Lyme disease

Cefuroxime (Ceftrin)is used to treat late Lyme disease.

Penicillin and erythromycin have been

shown to be ineffective.

Antibiotics are given orally during stage 1;

must be given intravenously in stages 2

and 3 to be effective.

Pre ention of L me Disease


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Prevention of Lyme Disease

1. Conduct tick checks after spending time

outdoors.

2. Tuck pants into socks to keep them offskin.

3. Use tick repellent (one with

___________________________

sprayed on clothing).

4. Insect repellents with DEET can be

used but are not as effective as

permethrin.

LYMErix vaccine


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LYMErix vaccine

LYMErix vaccine was used as a preventative in 1999, but wasmarginally effective and caused several side effects.

It has been withdrawn by its manufacturer and is no longer

available.

Triggers autoimmune arthritis in many. Class action law suit has

been filed against the manufacturer.

Lyme Disease in Domestic Animals


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Lyme Disease in Domestic Animals

Lyme Disease has also been shown to cause problems in dogs,

cattle, horses and cats, and is of veterinary importance.

Common symptoms in domestic animals is lameness, loss ofappetite and weight loss, and kidney disease.


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Human Babesiosis

Disease is caused by protozoan_________________________________

Vector is the deer tickI xodes scapularis

in Wisconsin and Minnesota

Remember that the parasite

normally occurs in meadow voles

but is transmitted from the vole to a

human via the deer tick bite

Causes _______________________

- life-threatening to

immunocompromised people

Human Granulocytic Ehrlichiosis


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Human Granulocytic Ehrlichiosis

Caused by the bacterium

_______________________________

Vectored by I xodes scapulari sin

Minnesota and Wisconsin

Ehrlichia invades human

______________________________

- white blood cells are destroyed and

infected persons show low wbc count

- fever, chills, headaches, muscle

aches common

60-80 cases reported in the Midwest each year - a few deaths have occurred

Diagnosed by IFA antibody test

Treatment with ___________________________________________________


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Mites

General Characteristics of Mites:

1. __________________________________(0.5 to 2 mm)

2. Bodies appear "hairy" due to presence of_____________________________________________

3. ____________________________ is hidden and unarmed

(no teeth).

4. Life cycle involves a single host; all life cycle stages are

found on this host:

egg 6-legged larva 8-legged nymph adult


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Sarcoptes scabiei

Common name: __________________________________

Causative agent of_______________________________(alsocalled the 7-year itch, or sarcoptic mange)

Cosmopolitan in distribution. Recent cases have been

identified in Eau Claire.


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Sarcoptes scabieiin Eau Claire


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Sarcoptes scabiei

small male large female


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Sarcoptes scabiei

Itch mites occur on human skin.

- Females tunnel within the

_________________________________

of the epidermisproducing tortuous

tunnels containing eggs, hatched larvae,and excrement.

- Larvae, nymphs, and males occur on the

____________________________

and do not burrow

Sarcoptes scabiei


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Sarcoptes scabiei

Burrowing female causes intense itching and a red rash appears.

Transmission is by direct physical contact between persons.

Acaricide drugs are effective in treating the infestation.


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Demodex foll iculorum

Common name:

____________________________Elongate mites with short, stubbylegs.

Live in ______________________

____________________________- most common on the face.

High prevalence in persons withacne and in older persons.

Mites generally do not cause anyproblems - mild skin eruptions mayoccur in some individuals.

Demodex canis


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Demodex canis

Common name: _______________________________

Causes ____________________________, a severe, often fatal rash in puppies.

Trombicula


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Common name:

_____________________________

The ______________________ of

several species ofTrombicula will bitemany mammals including humans.

Distribution in U.S. is primarily insoutheastern states

Morphology of larva: 3 pair legs;elongate legs; hairy body


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Trombicula

Chiggers in southeast Asia serve as vectors of

__________________________________, a rickettsialdisease caused byRickettsia tsutsugamushi.

Disease produces an extensive red rash.

Can be fatal if not treated with ________________________

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Arthropoda 7 Ticks Mites

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