Parasites Flashcards
What is this and how would you treat it?
Colic with an associated painful mass at the root of the mesenery is suspicious for verminous arteritis caused by damage to the cranial mesenteric artery and its branches by Strongylus vulgaris. The strongyle egg shown in the picture confirms the cause in this question. A number of anthelmintics are effective including benzimidazoles, pyrantel and ivermectin.
Praziquantel is effective against tapeworms. Rifampin and metronidazole are antibacterial drugs. Piperonyl butoxide is a pesticide synergist used in insecticide mixtures in horse
How do you treat Onchocerca?
The correct answer is there is no effective treatment against the adults. Treatment with ivermectin is only effective against the microfilariae of Onchocerca. Other drugs are ineffective against the adult helminths.
Blood smear showed signet ringed shaped organisms within erythrocytes. What treatment would you recommend to the owner and what is the prognosis?
ytauxzoon felis is a protozoal organism and transmission to cats is through tick bites. Cats usually show clinical signs 1-3 weeks after infection. Signs can be non specific and include anorexia, lethargy, dyspnea, and icterus. Cats will also commonly have a marked pyrexia. The organism invades the reticuloendothelial cells of the lungs, spleen, liver, lymph nodes, and other organs so cranial organomegaly can often be present. The bone marrow can be affected causing pancytopenias. Thrombocytopenia is likely related to the development of disseminated intravascular coagulation, which can cause spontaneous bleeding. There is no effective therapy and prognosis is poor to grave. Treatment is mainly supportive and involves IV fluids to maintain tissue perfusion and to correct dehydration, blood transfusions to improve the anemia and oxygen carrying capacity of the blood, and heparin therapy for prophylactic treatment of DIC.
Anti-protozoal medications such as imidocarb have been used with varying success. Corticosteroids and antibiotics such as doxycycline, enrofloxacin, and marbofloxacin are commonly used to treat Mycoplasma haemofelis, but they are ineffective against Cytauxzoon. Immune mediated hemolytic anemia, cholangiohepatitis, and FIP should also be considered as differentials.
Dermanyssus gallinae is known as the poultry red mite. They are nocturnal feeders and severe infestations can cause anemia and even death in severely infested animals. Management of Dermanyssus depends on effective treatment of the environment with residual insecticides. Individual animals can be treated with a variety of topical agents but long term management depends on environmental control.
Knemidocoptes mutans is also known as the “scaly leg mite” and affects chickens, pheasants, and pigeons. It causes lesions primarily on the legs and unfeathered parts although irritation can lead to feather picking. The lesions progress to appear thickened and encrusted. The adult females are short legged, round, up to 0.5mm in diameter.
Laminosioptes cysticola is the subcutaneous mite and typically causes 1-3 mm nodular subcutaneous lesions.
Ornithonyssus bursae are the tropical fowl mite and often infect the feathered regions around the vent. They spend the entire life cycle on the host.
Which of the following is a method of control to prevent infection of Metastrongylus lung worms in pigs?
The correct answer is to prevent access to soil containing earthworms. Earthworms are the intermediate host often involved in transmission of Metastrongylus lungworms in pigs. Direct transmission without the intermediate host can occur as well. Clinical signs include coughing and unthriftiness. If a secondary pneumonia occurs, dyspnea and abdominal breathing or “thumps” may occur. Affected pigs that are raised on pastures are often affected with both lungworms as well as ascarids.
Which tick is associated with tick paralysis in the United States?
The correct answer is Dermacentor. Tick paralysis in the U.S. is usually not fatal if the ticks are removed in time. Your major differential will be botulism. In Australia, Ixodes ticks are usually associated with tick paralysis, and the condition is usually fatal there.
A 2-year old rabbit presents for scratching its ears. On physical exam you observe crusts and excoriations in its ears. Microscopic exam of the crusts reveals numerous mites. You prescribe ivermectin to treat which parasite in this rabbit?
Psoroptes cuniculi, the rabbit ear mite, causes severe crusting and inflammation in the external ear canals. Treatment is ivermectin or selamectin. Encephalitozoon cuniculi is a microsporidian parasite of rabbits that causes neurologic and renal disease. Cheyletiella parasitovorax is the rabbit fur mite and causes white flakes that resemble dandruff. Otodectes cynotis is the ear mite of dogs and cats. Treponema paraluis cuniculi is the causative agent of rabbit syphilis.
A 3-month old kitten presents for mucoid diarrhea and anemia. You have recently seen several other puppies and kittens with similar clinical signs that were infected with Strongyloides stercoralis. What is the best way to confirm this diagnosis in this cat?
The correct answer is Baermann fecal technique. Strongyloides stercoralis mainly causes a mucoid diarrhea and possibly anemia in puppies and kittens. It passed in the feces in the L1 larvae form. The best technique for recovering larvae is the Baermann technique. Fecal flotations are good for eggs that float. Fecal sedimentation is good for eggs that sink, such as most fluke eggs. A direct fecal smear can find any type of egg or larva passed in feces but does not concentrate the sample to improve the yield in finding the eggs or larvae.
What is this and how do you treat? Pigs
The findings at slaughter are consistent with an infection of Ascaris suum. This is the roundworm of pigs. These worms can cause intestinal obstruction in large infestations. They can also migrate into the bile ducts and liver, causing the fibrotic liver lesions described in this case.
Antemortem diagnosis is made by fecal flotation and clinical signs. Treatment options are wide and include ivermectin, fenbendazole, pyrantel, levamisole and other ascaracides.
Endemically infected farms should employ on-going medication programs with routine benzimidazoles or ivermectins. Medication is aimed at prevention of mature intestinal infections by medicating finisher pigs at monthly intervals. In outdoor pig systems, careful attention must be paid to stock management, with field rotations, light stocking densities and regular anthelmintic treatment. Clearing sites of ascarid eggs is not practical unless floor surfaces can be flame treated. Ascaris suum eggs have thick coats and are highly stable and infectious in outdoor environments for several years.
Praziquantel is used to treat tapeworm infections but is not effective against roundworms.
A 3-month old kitten presents for mucoid diarrhea and anemia. You have recently seen several other puppies and kittens with similar clinical signs that were infected with Strongyloides stercoralis. What is the best way to confirm this diagnosis in this cat?
The correct answer is Baermann fecal technique. Strongyloides stercoralis mainly causes a mucoid diarrhea and possibly anemia in puppies and kittens. It passed in the feces in the L1 larvae form. The best technique for recovering larvae is the Baermann technique. Fecal flotations are good for eggs that float. Fecal sedimentation is good for eggs that sink, such as most fluke eggs. A direct fecal smear can find any type of egg or larva passed in feces but does not concentrate the sample to improve the yield in finding the eggs or larvae.
Infection of foals with the parasite whose egg is shown in the image below can be prevented by which of the following? The microscopic image was taken at 40X; the egg is approximately 50 um.
This image shows a Strongyloides westeri egg. Strongyloides pass from the host in the larvated form and are recognizable as an oval-shaped, thin-shelled embryonated egg.
Larvae of Strongyloides westeri are transmitted to foals in the mare’s milk. Adult horses rarely have patent infections except when larvae harbored in their tissues migrate into a mare’s milk after parturition. The worms are found in the small intestine and may cause diarrhea in young horses. Ivermectin or oxibendazole are effective in treatment of S. westeri.
Cobbleston or Moroccan leather in the abomasum
his is a description of type II ostertagiasis. The other parasites listed could be differentials with the exception of Dictyocaulus which is a lungworm. The main reason that Ostertagia is the best answer is the description of the abomasum. The cobblestone appearance which is also sometimes described as having a Moroccon leather appearance is essentially pathognomonic for Ostertagia. This occurs because Ostertagia larva undergo hypobiosis (larval inhibition) and lay dormant in the early fourth larval stage within the glands of the abomasum, forming the nodules. They resume development and emerge seasonally leading to severe signs.
On a cat’s annual exam, the owner complains about a chronic cough. You perform a routine fecal flotation and see double operculated eggs with asymmetric terminal plugs. What are these?
The correct answer is Capillaria aerophila eggs. Capillaria ova look similar to Trichuris eggs but are smaller and have asymmetric terminal plugs. Most cases of Capillaria are asymptomatic but chronic cough may be seen. Paragonimus is found by fecal floatation and have a single operculum. Aelurostrongylus larvae are recovered by Baermann.
What is the most common mode of transmission for thelazia?
face flies
Moniezia eggs are rectangular (as shown) or triangular. Moniezia is an anoplocephalid tapeworm found in young cattle. Their life-cycle involves oribatid mites which live in the soil and are ingested by the host. Moniezia are generally considered non-pathogenic but may cause intestinal stasis.
This is an image of Isospora suis, the cause of coccidiosis in pigs.
There are several anti-coccidial agents that can be considered in pigs although efficacy may vary. Ponazuril is an antiprotozoal drug approved for equine protozoal myeloencephalitis (EPM) that is active against the developmental stages of coccidia. Sulfamethazine, amprolium, and decoquinate are other anti-coccidial drugs. These agents reduce parasite burdens and shedding, but are frequently not completely effective at eradicating the parasite.
Nematodirus eggs have a characteristic elliptical appearance with sharply curved poles and 2-8 blastomeres surrounded by a wide fluid-filled cavity. Diagnosis can be difficult during the prepatent period when there may be little egg shedding.
Nematodirus season frequently coincides with coccidiosis season in the spring.
