Parasitology Part 2 Flashcards

Question

***_Heterophyes heterophyes_***

Answer 1

* **Adult Measures 1-2 mm in length by 0.3-0.4 in width and have a broadly round posterior end** * The surface of the worm is covered with minute spines * Eggs * are indistinguishable from those of Metagonimus yokogawai and resemble those of Clonorchis and Opisthorchis * **Examination of purged adult worms** * Heterophyiasis Symptoms * Little damage to the GI tract mucosa except for a mild inflammatory reaction * Heavy infections worms cause abdominal pain, mucous diarrhea, and ulceration of the intestinal wall * Eggs may provoke pathologic lesions, particularly in the heart and brain * Neurological symptoms due to adult worms or eggs in the brain have been reported * EPI * Acquired through the ingestion of pickled or uncooked/ raw fish * Can infect birds and mammals * China, Egypt, India, Iran, Israel, Japan, Korea, Sudan, Taiwan, the Philippines, Tunisia and Turkey

Answer 2

* **minute intestinal fluke, the smallest human fluke** * Diagnosis on the basis of clinical findings, patient history, or recovery of adult worms after therapy or at autopsy * Metagonimiasis Symptoms * Depend largely on worm burden of the host * Symptoms are diarrhea and colicky abdominal pain * Eggs infiltrate into the intestinal capillaries and lymphatics and are carried to the myocardium, brain spinal cord, and other tissues where emboli or granulomatous reactions may occur * Migration of the eggs to extraintestinal sites (heart, brain) can occur, with resulting symptoms * Metagonimiasis Diagnosis * **Microscopic identification of eggs (26-28 µm by 15 17 µm) in the stool** * Formalin ethyl acetate sedimentation concentration * Metagonimiasis Epidemiology * Far East, as well as Siberia, Manchuria, the Balkan states, Israel, and Spain * Human infections outside endemic areas may result from ingesting pickled fish or sushi made from fish imported from endemic areas * Metagonimiasis Prevention * control intermediate host (snails) by use of molluscidals * education to ensure all people fully cook all fish * implementing sanitary water conditions would reduce the continual reintroduction of eggs to water sources

Answer 3

* **Lung fluke** * Snail then crustacean then human * Cause paragonimiasis or pulmonary distomatosis, acquired through ingestion of raw or undercooked crabs or crayfish, is usually a lung infection * Adults Size * range **8 to 16 mm by 4 to 8 mm.** * The adult worm is a plump, ovoid, reddish * Paragonimus westermani * P. philippinensis * P. africanum * P. kellicotti * P. mexicanus * Adults possess oral and ventral suckers * Paragonimus Egg * **Eggs are yellowish-brown, 80-120 µm long by 45-70 µm wide, thick-shelled, with an operculum** * P. kellicotti has been acquired in the United States, with multiple cases from the Midwest. * Several cases have been associated with ingestion of uncooked crawfish during river raft float trips in Missouri * Paragonimiasis * 2-15 day incubation * Acute (in minority): * Diarrhea/ abdominal pain followed by * Fever, pulmonary symptoms: dyspnea, chest pain and bronchitis * Eosinophilia * Chronic symptoms * Cough, brown sputum * Chronic bronchitis/ bronchiectasis * Cysts, nodules, cavities, pleural effusions * confused with TB * CNS: headaches, seizures, visual disturbances, meningitis, mass lesions * Diagnosis: * O&P stool, sputum * Microscopic demonstration of eggs in sputum or stool on different days as a result of coughed up eggs that are swallowed * Eggs are also occasionally encountered in pleural effusion fluid or biopsy material * Complement fixation antibody test * Sensitive, but nonspecific * Becomes negative 6 12 months after cure * ELISA * 90% sensitive and specific * Takes 4 24 months to become positive after infection, longer to normalize after cure * EPI * Endemic mostly to Asia * Prevalence: China, Korea, Philippines, Japan, Vietnam, Taiwan, and Thailand * Also equatorial Africa, Peru, Equador * 20 million cases worldwide * 293 million at risk * **Acquired via undercooked crustaceans** * Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P. westermani * Treatment * Three doses praziquantel 25 mg/kg (in one day) * High cure rates * Prevention * Never eat raw freshwater crabs or crayfish Cook crabs and crayfish to at least 145 F (~63 C) * Travelers should be advised to avoid traditional meals containing undercooked freshwater crustaceans

Answer 4

* **Liver** * Require definitive and intermediate hosts for life cycles * Human is definitive host for * S. mansoni, S. japonicum, S. haematobium, S. mekongi , S. malayensis and S. intercalatum * S. mattheei causes infections in * sheep, cattle and horses; also infects humans and can cause disease * Differ from other trematodes in * **Live in the blood vessels** * **Have nonoperculated eggs** * **Sexes of adults separate** * **Transmission by skin penetration** * **(Bilharzia, Bilharziosis or Snail)** * Afflicts \>200 million worldwide * Significant cause of disease in endemic areas * **Acquired by (intact) skin contact with infected fresh water** * Mostly in tropics, areas of poor sanitation * **Bifurcate Cercaria** * Adult Worms * **Male worms are robust, tuberculate and measure 6 12 mm in length.** * **Females are longer, 7 17 mm in length, and slender** * Schistosoma mansoni Eggs * **114 to 180 µm long by 45-70 µm wide** * Schistosoma mansoni Symptoms * Symptoms are related to stages, previous host exposure worm burden and host response * Include: * Cercarial dermatitis * skin penetration and reaction * Acute schistosomiasis (Katayama fever ) * Associated with heavy primary infections and the initiation of egg production * Similar to serum sickness * High fever, hepatosplenomegaly, lymphadenopahty, eosinophilia and dysentery * Not well understood or common * **Passage of eggs through wall of intestine can produce fever, abdominal pain, liver tenderness, urticaria and general malaise** * **Immune response to antigenic substances released by egg** * ****

Answer 5

* **Urine!** * **110-170 µm long by 40-70 µm wide** * **Conspicuous terminal spine** * **Eggs contain mature miracidium when shed in urine** * Humans only significant reservoir hosts * Naturally infects monkeys, baboons, and chimpanzees * Pathology of S. haematobium schistosomiasis includes: * Hematuria * Scarring * Calcification * Squamous cell carcinoma * Occasional embolic egg * granulomas in brain or spinal cord

Answer 6

* Eggs are similar to S. haematobium in general, shape and in possessing a terminal spine, * **but are usually longer (140 240 µm), often have an equatorial (central) bulge and are shed in stool, not urine**

Answer 7

* Eggs are large and more rounded than other species * **70-100 um long by 50-65 µm wide** * **The spine is smaller and less conspicuous than other species** * Spine may be absent * **Eggs are shed in stool, sometimes urine** * Far East, including China, Indonesia, Japan, and the Philippines * Many reservoir hosts (cats, cattle, dogs goats, horses, sheep, pigs, mice, rats and water buffaloes) are naturally infected * Night soil issues

Answer 8

* Infections occur in the Mekong River basin in Cambodia, Laos, and Thailand * Dogs and rodents harbor the infection * Eggs similar to S. japonicum but **smaller with a range of 50-80 µm by 40-65 µm** * **Lateral Spine!**

Answer 9

* Pruritic, papular rash hrs 1 day after exposure (diff. from swimmer’s itch): cercarial dermatitis * More common in previously exposed * Acute/ toxemic schisto in some: Katayama Fever S. japonicum \> S. mansoni * 2-8 wks after infection (in previously unexposed) * Fever, headache, generalized myalgias, nausea, abdominal pain, hematuria, hepatosplenomegaly, diarrhea, cough, rash * Eosinophilia * Rare with S. haematobium * Rarely: CNS involvement * S. mansoni : transverse myelitis * S. japonicum : cerebral mass lesions

Answer 10

* Sequelae related to worm burden, duration of exposure * Immune reaction to eggs * Adult lifespan averages 3-7 years * Egg production: * 300/day ( S. mansoni ) vs. 3,000/day ( S. japonicum * Mainly in natives of endemic areas(vs. tourists or expats) * Likely contributes to anemia, growth retardation in children in endemic areas * Chronic GI schisto (S. mansoni, S. japonicum * Abd pain, diarrhea/ constipation, hepatic fibrosis (Symmer’s or “pipe stem”), hepatosplenomegaly, portal HTN * Liver failure rare * Chronic urinary schisto ( S. haematobium) * Hematuria, dysuria, strictures * Bladder cancer

Answer 11

* Microscopy (relatively insensitive): * **Increased by concentration techniques ( e.g., Kato Katz smear)** * Eggs appear 6-8 wk after infection * **Stool exam ( S. mansoni/ japonicum)** * **Urine exam ( S. haematobium ) midday sample** * Pathological * Serology * Not positive until at least 4-6 wk after infection * Remains positive indefinitely, even with curative treatment * Cannot differentiate recent from distant infection * Following titers not useful * FAST ELISA screening: * 95-99% specific for all three * Treatment * Praziquantel * Katayama fever: add steroids * Schistosomiasis Prevention * Mass chemotherapy programs * Snail elimination * Heat water to 125 o F for 5 minutes * Allow water to stand for 2 days * Fine mesh filter * Chlorination

Parasitology Part 2 Flashcards

(36 cards)