24. Arthropods (ticks) Flashcards
what is included in the class Arachnida?
- ticks
- mites
- spiders
- scorpions
how many legs do the larvae of Class Arachnida have?
6 legs
how many legs do the nymphal stages of Class Arachnida have?
8 legs
how many legs do the adult stages of Class Arachnida have?
8 legs
what is different about the number of legs in Class Arachnida and those in lice, fleas, bugs and flies?
lice, fleas, bugs and flies only have 6 legs, not 8, in the adult stages as well
do Arachnids have wings?
no, they are wingless
can ticks fly or jump?
no, they can only crawl
where do ticks wait for their hosts?
on the tips of grasses and shrubs, not from trees, at maximum 1m in height
what do ticks select their ambush site based on?
they have the ability to identify paths that are often travelled and they can sense the presence of the host
what is special about the sensory organs of ticks?
they are complex and they can determine trace amounts of gases, such as carbon dioxide left by warm-blooded animals and man
do ticks feed often?
no
what happens when ticks feed?
they acquire disease agents from one host and pass it to another host at a later feeding
do ticks that interact with humans and animals usually cause harm?
relatively few
how do ticks differ from other arthropods?
they lack antennae and the first pair of head appendages are modified to form pincer-like chelicerae
what are the 3 visible components of ticks’ mouthparts?
- palps
- chelicerae
- hypostome
what are the palps?
- they are highly mobile, jointed parts
- they move laterally while the tick is feeding and do not enter the skin of the host
what are the chelicerae?
- they are the two rough parts between the palps
- they are the cutting mandibles
what is the hypostome?
- the feeding tube
- the center rod-shaped structure
what does the hypostome have on it and what purpose do they serve?
- it has many beak-like projections
- this is so that, when it plunges into the host skin while feeding, it prevents easy removal
what does the tick also produce in its salivary glands?
a substance that attaches the feeding tick, and the substance dissolves after feeding is complete
what do ticks feed on?
the blood of their host
what is the function of the salivary secretions during a tick’s feeding?
it prevent blood coagulation so that it can continue feeding
what are the crucial steps of tick removal?
- gently grasp the head of the tick with fine tip tweezers, very close to the skin (to not squeeze its salivary glands, incase it harbours a parasite you will inject it into your blood)
- keep the tick in a sealed container to bring to the doctor
- wash both your hands and the location of the bite in soap and water
- swab the area with alcohol thoroughly
what can happen if the head of the tick breaks off under the skin?
it can result in an infection
how can breaking off of the ticks head be avoided?
do NOT twist upon tick removal
what are the two main groups of ticks?
- Ixodidae
- Argasidae
what are the Ixodidae?
- the hard ticks
- have a hard shield just behind the mouthparts (sometimes incorrectly called the head)
what is an example of the Ixodidae?
dog tick
what are unfed hard ticks shaped like?
flat seed
what are the Argasidae?
- soft ticks
- they do not have the hard shield and they are shaped like a large raisin
what do soft ticks prefer to feed on?
birds or bats
are soft ticks encountered often?
not unless the birds and bats are nesting or roosting in an occupied building
what are the 4 different life stages of hard ticks?
- egg
- larvae
- nymph
- adult
how many legs do the larvae of ticks that emerge from eggs have?
6 legs
when does the larvae molt to the nymphal stage?
after obtaining a blood meal from a vertebrate host
what do nymphs do after feeding?
they molt into the next and final stage, which is the adult
how many legs does the adult have?
8 legs
what happens after the adult hard ticks feed?
the adult female hard ticks lay one batch of thousands of eggs and then die
what is found in the Ixodidae?
hard ticks - they only take one blood meal per life stage except the egg stage
how much time does it take for ixodidae to complete an entire life cycle?
may vary from less than a year in tropical regions to over three years in cold climates,
what happens to ixodidae if hosts are not available?
certain stages may enter diapause until hosts are again available
how long can hard ticks go without feeding?
several months
what are the life cycles that hard ticks may undergo?
one-host, two-host, or three-host life cycles
what is found in the argasidae?
soft ticks
what is different about the soft ticks life cycle?
- they are not readily distinguishable
- unlike hard ticks, many soft ticks go through multiple nymphal stages, gradually increasing in size until the final molt to the adult stage
what is the first life stage to come out of the egg?
the six legged larva
what does the first, six legged larva do after hatching?
takes a blood meal
up to how many molts can some soft ticks pass through?
up to 7
how often do soft ticks feed?
several times during each life stage
how many eggs do females lay in soft ticks?
multiple small batches between blood meals throughout their lives
how long does it take for a soft tick to complete a life cycle?
generally longer than that of hard ticks, lasting over several years
what is the disease caused by Ambylomma?
- Lyme disease
- Rocky mountain spotted fever (RMSF)
what is the disease caused by Dermacentor?
- RMSF
- colarado tick fever
- lyme disease
- is also an agent of tick paralysis
what is the disease caused by Ixodes?
- lyme disease
- babesiosis
what is the disease caused by Rhipicephalus?
- RMSF
- lyme disease
what is the disease caused by Ornithodoros?
tick-borne relapsing fever
what is the disease caused by Carios?
tick borne relapsing fever
what are the other 2 nicknames for deer tick?
- bear tick
- sheep tick
what are the other common names for black-legged tick (deep tick)?
- Western black legged tick
- European wood tick
- Sheep tick
what are the other scientific names for Ixodes scapularis?
- Ixodes dammini
- Ixodes pacificus
- Ixodes ricinus
what are the diseases transmitted by Ixodes scapularis?
- lyme disease (deer tick)
- babesiosis
what is the dog tick also called? (nickname)
wood tick
what is the common name for dog tick?
American dog tick
what is the scientific name of the dog tick?
Dermacentor cariabilis
what is the disease caused by the dog tick
rocky mountain spotted fever
what is the scientific name of rocky mountain wood tick?
Dermacentor andersoni
what disease is caused by ricky mountain wood tick?
rocky mountain spotted fever
describe lyme disease
an infection caused by the spirochete bacteria Borrelia burgdorferi (North America) and Borrelia afzelii (Europe). It is transmitted by a bite from a black legged (deer) tick
what is the species of ticks assicated with Lyme disease?
Ixodes scapularis
does everyone get the red skin rash characteristic of lyme disease?
no, they might not even know they were bitten
what is used to treat lyme disease?
antibiotics - doxycycline
what happens if lyme disease goes untreated?
it can progress to a more serious disease involving the joints, nerves, and heart
can dogs and cats become infected with the lyme disease bacteria?
yes, but cats are far less commonly infected
are dogs often exposed?
yes they often are exposed but rarely become ill
what is RMSF caused by?
infection with the gram‐negative coccobacillus bacteria Rickettsia rickettsii
what is the most severe tick-borne rickettsial illness in NA?
RMSF
what are the primary vectors of RMSF bacteria?
The American dog tick (Dermacentor variabilis) and
Rocky Mountain wood tick (Dermacentor andersoni)
how does the disease usually begin in RMSF?
with fevers and feeling nauseous about a week after being bitten by a tick, although some people do not remember having had a tick bite
what happens a few days after onset of RMSF?
- people who have Rocky Mountain spotted fever often have a rash, usually on their arms or ankles
- They also may have pain in their joints, stomach pain, and diarrhea
what is the treatment for RMSF?
antibiotic - doxycycline
what is babesiosis?
an infection caused by a malaria‐like protozoan
how does the parasite of babesiosis enter the human?
when an ixodid tick, which is the definitive host of babesia, bites a human host and transfers the parasite while taking its blood meal
what is the causative agent of babesiosis?
- Babesia microti
- Babesia divergens
in what kingdom are the Babesia sp.?
protozoans (kingdom), malaria like parasites
how is human babesiosis or babesia transmitted?
by ticks
where is babesia found?
in NA and Europe
how long before a babesoisis patient shows symptoms?
1-4 weeks
what happens after the incubation period of babesiosis?
a person will show non‐specific disease signs and symptoms such as malaise, fever, headache and chills
what is the causative agent of most European babesiosis cases?
B. divergens
who are the susceptible ones to B. divergens?
splenectomized individuals
what is the treatment of babesiosis?
Most cases of babesiosis resolve without any specific treatment. For ill patients, treatment is usually a two‐drug regimen of quinine and clindamycin
