Flashcards in Spirurids Deck (35):
___ are tissue parasites transmitted by bloodsucking insects, microfilaria accumulate either in blood or connective tissue.
What is the intermediate host of D. immitis?
(only form of transmission)
What is the primary definitive host of D. immitis?
What percentage of mosquitos may be D. immitis positive?
What percentage of mosquitos may be D. immitis positive near a positive animal?
Where can D. immitis be found within the body?
Based on the eggs released, what are the D. immitis females?
Where does the larva change from L1 into L3?
In malpighian tubules of the mosquito
How long does it takes these to go from a microfilaria to an infectious L3 inside the misquito during transmission season?
After becoming L3s in the misquito, to where do they migrate within the body?
Explain the process of the mosquito bite and the larva entering the host.
L3 exit labrum when mosquito feeds and enter the bite wound. L3 --> L4 takes 3-4 days. L4 --> L5 takes 45-65 days. Immature adults (L5) migrate within muscle cells to blood vessels. From there they enter pulmonary arteries. L5 --> Adulte = 6-9 months (prepatent period)
How long does it take the the L3 to develop into L4 in the host?
What does the heartworm test detect?
Antigen produced by ADULT females
What can the ELISA antigen test be used for?
What are 3 cases where an animal would come up with a FALSE NEGATIVE?
1. All male infection
2. Infection with low # of females
3. Infection with immature females
What are some causes of an occult heatworm infection?
1. Infection with only females
2. Use of HW preventatives that kill the microfilaria
3. Maturing adult females present
4. Immune-mediated clearance of microfilaria
What is the GOAL of HW treatment?
Eliminate all life cycle stages of HW with minimal post treatment complications
How might you eliminate adults?
2. Surgical removal
Which life stage do you eliminate first?
Follow up with adults
What are the 3 things you should assess prior to treating HW adults?
1. Activity level
2. Physical exam, chest radiographs, blood work
3. Worm burden
What do macrocyclic lactones treat?
What does melarsomine treat?
1. L3s and L4s
2. Adults only
How do you treat a HW positive dog before treating with melarsamine?
Killing the Wohlbachia bacteria helps in treatment
Treat with doxycycline + IVM
If you get rid of Wolbachia, what is lost in the embyro?
Asymmetry - will not develop properly
What restriction do Melarsomine treatment dogs require?
Explain the Melarsomine treatment.
2 doses 30 days later 24 hours apart
At what point should an antigen test be negative after treatment?
6 months later
How often do you perform an antigen test?
Start puppies on prophylaxis no later than ___ weeks old.
In older puppies (
1. 6 months
2. 1st dose
Differ the HW disease in cats from that in the dog.
1. Cats more resistant
2. Fewer L3 mature to adults
3. Mature more slowly
4. Shorter adult life span
5. Fewer adult worms in the heart (antigen test will not work as well)
6. Less worms required for disease
What does the antibody test confirmed?
An infection has occurred
Why does the antigen test have a high incidence of false negatives?
Fewer worms present
Does the AHS recommend giving a feline the adulticide melarsamine? Why or why not?
NO - this is potentially toxic to the cat and will NOT increase survival
What is the prevention protocol for feline HW?
Monthly oral or topical macrolides