Parasitology: Overview & Helminths (Wilson) Flashcards
_____ is the standard treatment for all flatworms (both flukes/Trematodes and tapeworms/Cestodes), in which the human host role is definitive
Praziquantel
this subspecies of Schistosoma releases its eggs in the urinary tract causing obstructive uropathy, pyleonephritis, bacteruria, and squamous cell bladder cancer
S. haematobium
Treatment of parasites that invade tissue (eg, Strongyloides and lymphatic filariae such as Onchocerca volvulus) requires this medication, which is well absorbed systemically, albeit toxic.
Ivermectin
Which of the following statements regarding Cestode infections is FALSE?
A. Hymenolepsis nana maintains its entire life cycle in a single host, similar to Strongyloides.
B. Taenia saginata is the only Cestode that does not use a human intermediate host.
C. Echinococcus granulosus is the only Cestode whose definitive host is not exclusively humans.
D. The Taenia species come in two varieties - one that resides in beef (T. solium) and another in pork (T. saginata).
E. Eating meat with cysts results in milder infections with adult tapeworms, whereas eating excreted larvae results in more serious disseminated disease.
D. Backwards! T. solium is a pork tapeworm and T. saginata is the beef tapeworm.
syndrome associated with strongyloides infections, resulting in gram negative sepsis, meningitis, pneumonia, and 86% mortality
hyperinfection syndrome
*occasionally there wil be eosinophilia also
what is the primary difference between the life cycles of Strongyloides and hookworms?
whereas maturation of hookworms requires 2 weeks of growth in the soil, the maturation of Strongyloides can happen either in the soil, on the skin, or internally (particulary in an immunocompromised peron, or one on immunosuppressants).
symptoms of infection with this large intestinal nematode are broken down into 3 phases:
- Pulmonary - Loeffler’s syndrome, marked by eosinophilia and pulmonary infiltrates
- Intestinal
- Complications - intestinal, bile or pancreatic duct obstruction
ascaris lumbricoides
Which of the following statements regarding filarial infections is FALSE?
A. Filariae are diagnosed as adult worms circulating in the blood.
B. Wuchereria bancrofti and Brugia malayi are lymphatic dwelling filariae that both have mosquito vectors.
C. A patient suspected to have a Wuchereria bancrofti or Brugia malayi infection should have blood drawn at night due to these organisms nocturnal periodicity.
D. Lymphatic filariae may cause a variety of syndromes, including tropical pulmonary eosinophilia.
E. Onchocerca volvulus is the 2nd most common cause of infectious blindness worldwide and is transmitted by the black fly.
A. These diseases are diagnosed at the microfilia stage, while immature larvae are circulating in the blood, skin or eye.
Which of the following statements regarding Onchocerca volvulus is FALSE?
A. It is colloquially known as river blindness.
B. Diagnosis is made by the presence of microfiliariae in the skin.
C. Adult worms tend to reside in nodules over bony prominences.
D. Symptoms include severe itching, bumps under the skin, and lymphadenopathy.
E. The safest and most effective treatment includes DEC + Albendazole.
E. DEC is really too toxic for treatment of this condition and may result in massive inflammation in response to sudden widespread death of filariae in the eye, causing blindness. The best treatment is Ivermectin + Abendazole.
All of the following are nemotodes (roundworms) EXCEPT:
A. Wuchereri bancrofti
B. Enterobius vermicularis
C. Trichuris trichiura
D. Ascaris lumbricoides
E. Strongyloides stercoralis
A. Wuchereri bancrofti is a filaria.
this cestode is prevalent in regions where dogs are used to herd livestock, and it uses humans as incidental intermediate hosts; causes the formation of hydatid cysts in the liver that, when rupture, may lead to anaphylaxis
echinococcus granulosus
Which of the following statements regarding T. saginata and T. solium is FALSE?
A. Taenia species are indistinguishable on a stool Ova and parasite exam.
B. T. saginata symptoms include dull abdominal pain that is relieved by food, nausea, diarrhea or constipation with change in appetitie
C. T. saginata is known to disseminate, particularly to the CNS.
D. On biopsy, T. saginata tends to be a longer organism with more proglottid branching.
E. Both T. saginata and T. solium are self-limiting diseases.
C. This is T. solium, which is the most common helminth in the CNS.
Which of the following statements is FALSE?
A. Protozoa are unicellular organisms that multiply in the human host while Helminths are multicellular organisms
B. A definitive host harbors the adult stage of the parasite
C. An intermediate host harbors the asexual stage of the parasite
D. Eosinophilia occurs only during infection with protozoa during tissue migration
E. A reservoir may be an animal host or a physical location, like the soil.
D. Eosionophilia occurs exclusively during an infection with helminths, as they migrate through tissue.
Which 3 nematodes are spread by the fecal-oral route?
Enterobius vermicularis (pinworms), Trichuris trichiura (whipworms), and Ascaris lumbricoides
Usually helminthinc life cycles cannot be completed in a single host and worms die over time - autoinfections by what two organisms are the exception to this?
Strongyloides stercoralis and Hymenolepsis nana
*these organisms are retained long term and cause hyperinfection in infected people who become immunocompromised
