Others of Importance

Question 1

ECHINOCOCCUS GRANULOSUS

(TAPEWORM)

Answer 1

• only 3-4 segments(proglottids)
• scolex buried deep in an intestinal crypt (find through mucosal scraping)
• Final Host: CANIDS (dog, fox)
• PPP: 6-7 wks
• 1 gravid (fertilied section) shed per adult per week
• Intermediate host: OTHER MAMMALS- metacestode only found in these animals, hydatid cyst: produce 100,000 protoscolices/ml

Question 2

ECHINOCOCCUS MULTILOCULARIS

(fox tape worm)

Answer 2

• more proglottids!! (about 5)
• sac-like uterus (200-300 eggs)
• DIRECT HOST: foxes
• Intermediate host: RODENTS (voles)
• Invasive metacestode: alveolar cyst (infiltrates liver like a tumor)
• NOT IN UK YET
• urban foxes

Question 3

TOXOCARA CANIS

(nematode in puppies!!- Dog Roundworm)

Answer 3

• Hosts – dogs, foxes, other canidae
• Adults- cream, fleshy, up to 18cm long, live in the s. intestine
• Eggs – dark, pitted surface, round, 80μm
• hepato tracheal route: s. intestine–> hepatic portal system–> liver–> heart (venous return)–> Lungs –> coughed up for second infection!!
• OR: IN UTERO (see egg excretion at 2-3 weeks of age)
• older dogs: don’t infect a second time, go back to somatic tissues where they are distributed and enter a waiting phase--> granulomas. WAIT FOR PREGNANCY- distracts host IS will cuticle sloughing. most go to prenatal infection (90%), rest to transmammary infection
• wait in paratenic host to be eaten: FOXES in urban areas
• Infection is by ingestion of L3

Question 4

ANGIOSTRONGYLUS VASORUM

(french lungworm)

Answer 4

• Final Hosts: Dogs and Foxes
• Intermediate: MOLLUSKS
• not zoonotic
• PPP: 6-10 weeks
• adults: found in pulmonary arteries on right side of heart
• eggs: go to pulmonary arteries and get trapped in lung capillaries–> L1 hatch out–> alveoli causing small damage–> trachea to be swallowed–> passed in faeces–> slug infected (grow into L3)- then host gets by eating molusk or frog (paratenic host)–> mesenteric lymphnodes–> L5–> Liver–> R. Ventricle of pulmonary artery (adults)
• Foxes are a big final host pop atm (resevoir for dogs)

Question 5

DIROFILARIA IMMITIS

(Canine Heartworm)

Answer 5

• WARM HUMID CLIMATE
• Issue in SO. Europe!! could come up north!!
• LONG PPP
• signs: exercise intolerance, chronic heart failure or collase
• Not Eggs: MICROFILARIAE- can find in circulating blood (if not: only immature worms present or one sex)
• Intermediate host: MOSQUITO- L3 stage transmitted by mosquito. In mosquito: mf–> L3 (needs to be 14C at least)
• L3 enter via puncture on skin from mosquito feeding
• larvae will molt and reach pulmonary arteries in 4 mo. –> diffuse eosinophilic reaction in lung then back up to heart to produce microfilariae
• VERY PATHOGENIC IN CATS
• zoonotic: human is a paratenic host

Question 6

LEISHMANIA

Answer 6

• zoonotic!
• Leishmania spp. are intra-cellular, protozoan parasites of macrophages- Closely related to trypanosomes
• transmitted by blood sucking sandflies!
• amastigote form is found in vertebrate macrophages–> sucked up by sandlfy–> promastigote form
• most dogs are asymptomatic
• SANDFLY NEEDS TO BE PRESENT IN AREAS if to be endemic