dirofilaria immitis kristi bjerke & heather lee. taxonomy class: secernentea subclass: spiruria...
TRANSCRIPT
Taxonomy
CLASS: SECERNENTEA• SUBCLASS: SPIRURIA
– ORDER: SPIRURIDA•SUPERFAMILY: FILARIOIDEA
– FAMILY: ONCHOCERCIDAE » Scientific name - Dirofilaria immitis» Common name - Dog heartworm
Hosts
• Definitive Host: dogs, foxes, wolves, coyotes, cats, ferrets, sea lions
• Intermediate Host: Over 70 species of mosquitoes
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Geographic Distribution
• Worldwide– Most common in mild and warm
climates
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Morphology• Adults are long,
white, thread-like worms– Females 25 to
30cm long– Males 12 to 16
cm long with spirally coiled tail
Morphology
• give live birth and the baby worms are called Microfilariae
• Microfilariae– Sheathless– 218 to 329µm long – have a long pointed tail
Life Cycle• A dog infected by microfilariae is bitten
by a mosquito• If the microfilariae is not picked up by a
mosquito after 2 years, they die of “old age.”
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
•Microfilariae can be transmitted across the placenta.•Puppies will not develop adult heartworms because the microfilariae didn’t go through the intermediate
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Life Cycle• Inside the mosquito, the
microfilariae develop to L2’s and finally to L3’s.
• The L3 is the infective stage for dogs.– Takes a few weeks– Temperature dependant
• Minimum of 57 ºF is required
Life Cycle
• The L3 is deposited in mosquito saliva next to the bite and then migrate into the body.
• The average mosquito can only transmit a maximum of 10 infective larvae at one time
• The L3 larvae then live in the dogs skin where they develop into an L4 stage.
• They then live in the subcutaneous tissues and muscle for 3 months before they finally molt into an adult.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Life Cycle• Adults migrate to the right side of
the heart and into the pulmonary arteries and lungs where they mate and produce microfilariae.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
–The overall maturation and migration process until mating takes approximately 5-7 months–Adult worms can live in the dog for up to 5 years
Pathogenesis of the Heart• Heavy infections(over 25
worms for a 40 lb dog)– worms begin to back up
into the right ventricle • less blood pumped.
• Over 50 worms the ventricle is full and the atrium begins to contain worms.
• Over 100 worms the entire right side of the heart is filled – phenomenon is called
"Caval Syndrome" and most dogs do not survive it.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Canine Symptoms• Cough, exercise intolerance• dyspnea (difficulty breathing)• abnormal lung sounds• hepatomegaly (enlargement of the
liver)• syncope (temporary loss of
consciousness due to poor blood flow to the brain)
• ascites (fluid accumulation in the abdominal cavity)
• abnormal heart sounds• death
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Feline Symptoms• Non-specific generic signs of illness
– Vomiting intermittently– Lethargy– Lack of appetite– Weight loss– Coughing– Asthma-like signs– Gagging– Difficult or rapid breathing
• The early signs (when worms are carried to the pulmonary arteries) are often misdiagnosed as asthma or allergic bronchitis– Actually Heartworm Associated Respiratory Disease
(HARD)
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Heartworm in Cats vs. Dogs
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Diagnosis
• Blood Tests– Filter test to look for microfilariae
• Doesn’t work well for small infections
– Antigen test screens for pieces of adult heartworm skin in the blood
• Only works for female worms• Need at least 3 for it to be detected
– Newer tests test for antibodies
• X-rays– Enlargement of lobes of lungs or right side
of heart
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Treatment
• Adulticide– Melarsomine dihydrochloride
(Immiticide®)• Intramuscular injection into lumbar muscles• Complications include thrombosis (clogging) of
pulmonary arteries due to dead worms
– No current treatment for cats
• Microfilaricide– macrocyclic lactone (ML) anthelminthics,
i.e.,milbemycin oxime, selamectin, moxidectin and ivermectin
– Commonly used in heartworm preventative
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Control/Prevention• Can be given as
– Monthly Tablets– Chewables– Topicals
• Ivermectin– Heartgard, Heartgard Plus, Tri-Heart, Iverheart Plus
• Milbemycin oxime– Interceptor, Sentinel
• Selamectin– Revolution
• Moxidectin– Advantage Multi
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
http://www.heartwormsociety.org/quiz.asp