Exam 1 Review

Parasite is an organism which lives on another animal called its host and parasite is dependent metabolically on it.

True

Parasitism is an association, which enables parasite and host to benefit from each other.

Wrong/False

Definitive (final) host has the sexually mature (adult reproducing) stage of the parasite.

True

Paratenic host harbours the immature ineffective stage to spent on it and cannot get rid of it.

True

Routes of entry of parasites are: natural openings (mouth and external openings of reproductive organs), Skin penetration, transplacental entry, transovarian transmission, and involvement of vectors

True

Effects of parasites on their hosts include absorbing readily digested food material intended for the host

True

Indirect life-cycle involves necessarily one or more intermediate hosts or vector to complete its life cycle.

True

Spirocerca lupi lives mainly in fibrous nodules formed in the walls of the oesophagus and stomach

True and they are sometimes also found in the lymph nodes, lungs, bladder, or arteries

Dogs cannot become infected with Spirocerca lupi by consuming paratenic hosts.

Wrong/Flase

Eggs containing Toxocara larvae are ingested by a young puppy or kitten (under 6 months old) they cannot migrate through the intestine and eventually develop into adults.

Wrong, they migrate and develop into adults

When embryonated eggs of Toxocara spp. are ingested by dogs or cats (6 months or older) the larvae migrate to the lungs, head for the heart through the pulmonary veins and they are distributed throughout the body in the bloodstream to become encysted in various organs while still alive.

True

Toxocara canis larvae cannot reactivate in bitches when they are on heat but only just before giving birth.

Wrong, both times is possible

The larvae that infect puppies prior to birth will develop into adults when the puppies are 10 days old.

True

Larvae ingested from the colostrum or milk will migrate through the puppies’ bloodstream and lungs, before developing into adults in the intestine.

True

There is no in utero passage in queens, but Toxocara cati larvae will infect kittens through their mother’s milk from the second day after birth and for about 10 days thereafter

True

Respiratory disorders, including coughing is seen first, before other clinical signs occur (respiratory disorders correspond to the passage of the larvae from the pulmonary arteries to the alveoli and then the bronchi, before being swallowed and entering the gastrointestinal tract to become adult worms).

True

Females should be dewormed when they are in oestrus to prevent toxocarosis.

True

Any antihelminthic nematicide can be used to destroy adult Toxocara spp. worms, including reactivating or migrating larvae.

Wrong, standard antihelminthic nematicides can be used to destroy adult Toxocara spp. worms, but only dewormers which diffuse into the tissues (e.g., fenbendazole, selamectin, eprinomectin) will stamp out reactivating or migrating larvae

Puppies and kittens should be dewormed against Toxocara spp. at 15 days old (or at 10 days in cases of heavy infection) and then every 15 days until they are weaned.

True

Both T. canis and T. cati are potentially zoonotic, but T. leonina does not present any danger to humans.

True

Ancylostomosis is a helminth infection caused by the penetration or ingestion and migration to the small intestine of Ancylostomatidae nematodes (hookworms).

True

Hookworm larvae may mobilise at birth and infect the young through the mother’s milk.

True

Hookworm infection includes cutaneous signs due to skin penetration of the L3 larvae. These inflamed areas become itchy and the lesions can become infected and develop into pyoderma.

True

Ancylostomosis should be considered in dogs with epistaxis, associated gastrointestinal disorders and weight loss.

True

Ancylostoma worms are relatively sensitive to nematodicides, such as praziquantel.

Praziquantel is not a nematodidide

Hookworms from dogs and cats may infect humans with a complete life cycle (A. ceylanicum) or cutaneous larva migrans after penetration through the skin (A. braziliense, A. caninum, and rarely U. stenocephala)

True

Threadworms are long slender nematodes measuring 10-12 cm in length.

Threadworms are small, slender nematodes measuring 2-9 mm in length

All females Strongyloides are parasitic and they produce eggs without males being present.

Only the parthenogenetic female Strongyloides can do this

In immunocompromized hosts, the eggs laid by the parasitic Strongyloides females may hatch and develop inside the host, producing stage 3 larvae and new generations.

True

Infection with Strongyloides is mainly by ingestion through the mouth is of secondary importance (most stage 3 larvae ingested are destroyed in the stomach).

Infection with Strongyloides is mainly by skin penetration. The infection by ingestion through the mouth is of secondary importance (most stage 3 larvae ingested are destroyed in the stomach)

Prevention of strongyloidosis is based on regular disinfection of breeding facilities and kennels and keeping them clean, as well as treating females before birth of their young.

True

Trichuris : this parasite causes gastritis

No, it causes colitis

After Trichuris eggs, containin glarvae, are ingsted and the larvae are released, complete development takes 10-12 weeks. This development occurs with no systemic migration, the larvae remaining in the wall of the intestine

True

Trichuris eggs do not survive in the soil longer than 2 weeks

Trichuris eggs in the soil can survive for several years, where they are not particularly sensitive to extreme weather conditions (cold, drought) or to ordinary disinfectants

Trichuris worms are usually equally sensitive to antihelminthics with other common nematodes (roundworms and hookworms)

Wrong, they are less sensitive

The presence of tapeworm segments in the perianal region and signs of perianal itching are common causes for consultation.

True

The life cycle of Dipylidium caninum includes as intermediate host the flea.

The lifecycle is dixenous, i.e., it includes as intermediate hosts the flea (most common) and the louse

Flea larvae actively ingest several types of debris in their environment, including hairs, skin debria, and also faeces or Dipylidium proglottids, so the flea larvae can ingest the oviferous capsules in the gravid terminal segments.

True

The metacestode larvae of Dipylidium must be ingested in a flea by the dog or cat during grooming in order to develop to adult cestode

True

Licking of the perianal region can cause Dipylidium eggs to be deposited on the animal’s fur.

True

Clinical diagnosis of Dipylidium infection is impossible, except when proglottids are visible

True

Praziquantel (5 mg/kg bw) is effective against Dipylidium infection.

True

Mesocestoides life cycle requires two intermediate hosts. The first is an arthropod, which harbours the cysticercoid larvae. The second is an insectivorous vertebrate, which harbours an elongated larva called tetrathyridium.

True

Carnivores become infected by ingesting the faeces of the second intermediate hosts which harbour the tetrathyridium.

By ingesting the whole second intermediate host that harbors the tetrathyridium

Clinical diagnosis is possible. No need of X-ray or ultrasound scans to diagnose ascites. No need for abdominocentesis to confirm diagnosis.

Clinical diagnosis is not possible. Ascites may be diagnosed by X-ray or ultrasound scan, and then confirmed on abdominocentesis, when the numerous white grains will be seen

The hydatid cysts can grow in various tissues and organs, usually the liver and lungs of the intermediate hosts (usually ruminants).

True

After ingestion of infected organs, the adult cestode (Echinococcus granulosus) will develop in the intestine of Canidae (E.g. dogs, wolves, coyotes).

True

Echinococcus granulosus develops into the adult stage also in the cat, which therefore plays an important role in the epidemiology of hydatid disease.

Wrong/Flase

Cats can be infected with Echinococcus multilocularis, which very commonly sheds oviferous segments.

Wrong, this happens very rarely

Echinococcus granulosus is a small cestode, 3-6 mm long, and consists of 4 to 5 segments, only the final segment being oviferous.

True

The definitive hosts of Echinococcus multilocularis are red and Arctic fox, wolf, racoon, jackal, coyote, etc. The intermediate hosts are rodents (mainly voles) primates, etc.

Correct

Hydatid echinococcosis is found worldwide and is highly enzootic in important sheep-farming regions and developing countries.

Correct

Mechanisms of infection in intermediate hosts include ingestion of food or water contaminated with any worm segments or eggs

Mechanisms of infection in intermediate hosts include ingestion of food or water contaminated with oviferous segments or eggs

Possible contamination of humans if eggs are present on the dog’s coat.

True

Hydatidosis in animals is usually asymptomatic. It results in the formation of hydatid cysts consisting of larvae surrounded by the inflammation caused by host’s adventitial tissue response.

Correct

Prevention in the intermediate host includes i) inspection of carcasses and destruction of infested offal and ii) prevention of illegal slaughter of ruminants or pigs

Correct

Cryptosporidium: These parasites become established in the brush border of the enterocyte without penetrating the cytoplasm.

True

Cryptosporidium oocytes consist of two types: 1) Thin-walled oocysts which can shed their sporozoites in situ to start a new cycle and 2) Thick-walled oocysts, which are shed into the environment in the faeces.

Correct, both types of oocysts are produced

Cryptosporidiosis due to C. parvum is a disease which mainly affects young animals in their first weeks of life and to a lesser degree, older animals with compromised immune systems.

Correct

Cryptosporidium oocysts are sensitive to desiccation, heat (destroyed in 30 minutes at 65°C) and cold (destroyed in 24 hours at -18°C).

They are sensitive to desiccation, heat and cold

Cryptosporidiosis is often asymptomatic in dogs and cats. Persistent or intermittent diarrhoea is seen in clinical cases (often in puppies and kittens), causing weight loss, emaciation and a change in the general condition of the animal.

True

Isospora spp. appear in different forms, including free forms in the intestinal lumen.

Correct

Isospora oocysts shed into the external environment must undergo sporulation in order to become ineffective.

True

Sporulated Isospora oocysts consist of a smooth wall enclosing two sporocysts, each containing four sporozoites.

Correct

Isospora oocysts are very resistant and can survive in the environment for 1 to 2 years, but they are sensitive to desiccation, heat (destroyed in 30 minutes at 60°C and 7 days at 25°C) ultraviolet light and cols (destroyed in 3 months at 0°C).

Correct

Toltrazuril and diclazuril are both drugs given orally to treat Isospora infection in dogs.

Correct

Giardiosis is a flagellate protozoan infection of the small intestine, characterized by the development of enteritis with chronic diarrhoea, often appearing steatorrhoeic.

Correct

Giardiosis occurs worldwide; it is readily spread because the parasitic reservoir consists of a great number of asymptomatic carriers.

Correct

Giardiosis is an infection shared by animals and humans, although the genotype (known as “assemblages” for G. duodenalis) adapted to each species is quite distinct

Correct

Giardia trophozoite stage is rarely seen, except on examination of fresh faeces.

Correct

Asymptomatic animal carriers are sources of the parasite and infection takes place when cysts are ingested.

Correct

The acute form of giardiasis is characterized by watery diarrhoea, colic and bloating, and a change in the overall condition of the animal.

Correct

The chronic form is characterized by pasty, foul-smelling diarrhoea and steatorrhoea which causes faeces to be yellowish and fatty.

True

Giardiosis is probably the most common intestinal protozoan disease in carnivores but its prevalence is underestimated due to the limited number of faecal examinations carried out in veterinary clinics.

Correct

Feline Tritrichomonas blagburni infection is characterized by waxing and waning diarrhoea that often contains fresh blood or mucus. In most cases, the general condition of the cats remains good.

TrueMo

Dirofilaria immitis is characterized by the development of heart failure with the gradual onset of other cardiorespiratory signs.

Correct

Male Dirofilaria immitis are 12-20 cm long with a diameter of 1mm and the posterior end is spiral-shaped. Females can be up to 30 cm long and the same diameter. Both are of a whitish colour.

Correct

The intermediate host if Dirofilaria immitis, a female mosquito (Aedes, Culex, Anopheles), ingests the microfilariae during a blood meal

True

The prepatent period is very long, about 6 months, sometimes longer.

True

Microfilariae of Dirofilaria immitis can be transmitted from a female dog to her puppies via the placenta, or between dogs by transfusion. Microfilariae will continue to circulate in blood but will not develop further.

True

Only Dirofilaria immitis L3 transmitted by mosquito vectors will develop into adult filariae.

Correct

Other biting arthropods (fleas, lice, ticks) are never involved in the transmission of Dirofilaria immitis, but they may be vectors of other filariae (Acanthocheilonema genus).

Correct

Stage 3 of heartworm disease corresponds to severe clinical signs. The animal presents with tachycardia and dyspnoea as well as coughing at rest, ascites, chronic renal insufficiency, and often exhibits cyanosis of the mucous membranes.

Yes, possible

Unlike radiography, echocardiography enables cardiopulmonary dirofilariosis to be diagnosed by visualizing the adult filariae.

Yes, true

Some dogs are described as being amicrofilaremic because they do not have microfilariae. There are various reasons for this including infection by male filariae onyl or by old filariae, treatment with avermectins or milbemycins or their destruction by the immune system.

Correct

Currently available rapid filarial antigen tests detect circulating blood proteins secreted by Dirofilaria immitis adult females.

Correct

Chemoprophylaxis against heartworm diseases is based on the use of macrocyclic lactones

Correct

The life cycle of Angiostrongylus vasorum i sdirect

Wrong, it is dixenous

In the canine definitive host, adult Angiostrongylus vasorum worms live in the branches of the pulmonary arteries and arterioles, where they cause arteritis and disrupt pulmonary perfusion.

Correct

Dogs are infected with Angtostrongylus vasorum by eating the mollusc, but not the L3 released by a dead gastropod, which cannot survive in the external environment.

Wrong, L3 can survive a period at the environment

Dogs are infected with Angiostrongylus vasorum by eating a paratenic host.

True

Angiostrongylus vasorum L3 larvae have been shown to be excreted in the slime of gastropods and these are often found around carnivore eating areas. Food could therefore be contaminated in this way.

Correct

Since Angiostrongylus vasorum are fairly prolific, the sensitivity of coproscopy is adequate, but faeces should be collected for 3 consecutive days as excretion is intermittent.

True

Angiostrongylus vasorum larvae can be demonstrated in bronchoalveolar lavage fluid.

Correct

Aelurostrongylus abstrusus worms are haematophagous.

Correct

Aelurostrongylus abstrusus are found in small nodules in the lungs as a result of inflammatory infiltration.

Correct

Aelurostrongylus abstrusus L1 larvae actively penetrate their intermediate hosts (molluscs: snails or slugs), where they develop into the third, ineffective stage (L3) in approximately 3-5 weeks.

Correct

The cat becomes infected with Aelurostrongylus abstrusus by eating snails and paratenic hosts.

Correct

The cat becomes infected with Aelurostrongylus abstrusus by eating L3 larvae released after the death of snails, intermediate host, or larvae released in the mucus of living gastropods.

Correct

Educating local populations not to distribute raw offal to carnivores is not considered a prevention step against hydatidosis-echinococcosis.

Wrong, it is an important step