parasites Flashcards

Question

three characteristics of pathogenic nematodes

Answer 1

Smooth borders, Even shapes with tapered ends, Not pigmented

Answer 2

 GI - Abdominal discomfort, Bloating, diarrhea, perianal itching, Malabsorption  Pulmonary – Pneumonitis, Transient infiltrates – migrate through the lungs, wheeze  Skin • Cutaneous larva migrans  Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it • Hives (both hookworm and Strongyloides)IgE reaction to the worm causes generalize allergic reaction when invading into mucosa  Nutrition/Hematologic - Fatigue due to iron deficiency (hookworm), Vitamin A/Zinc deficiency, & Protein losses

Answer 3

nematode Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it

Answer 4

a vicious cycle  Anemia (esp. hookworm)  Reduced work output, Impaired cognitive ability, and Decreased school attendance  This leads to… poverty – contributes to poor levels of sanitation/education and more helminth infections

Answer 5

SKIN --> LUNGS --> GUT

Answer 6

gut --> liver --> lungs --> gut

Answer 7

igE | pulmonary eosinophilia

Answer 8

most common helminth; largest nematode (up to 40 cm) One female can lay up to 200,000 eggs/day  Worms will crawl out if the host is anaesthetized or has a fever  Life Cycle • Eggs in soil (remain infective for years)  embryonated eggs ingested  larvae hatch and molt in bowel  migrate in the blood to the lungs (PULMONARY EOSINOPHILS – loefflers syndrome) ascend airways to glottis and are swallowed  become adults in GI tract and cause obstruction, malnutrition, infection, can also obstruct biliary/pancreatic ducts  lays up to 200,000 eggs which are pooped out and continue cycle  Clinical Manifestations • Most patients: asymptomatic • GI: abdominal discomfort, Intestinal obstruction, Biliary/pancreatic obstruction (aberrant migration) • Pulmonary: Löeffler’s syndrome (transient pulmonary infiltrates, dyspnea, dry cough, occasional fever, and eosinophilia)  Diagnosis • Will not find eggs until 2-3 months after pulmonary symptoms occur – sputum may have Charcot-Leyden crystals • After 2-3 months, easy to find eggs since females make 200,000/day  Treatment • Pulmonary disease: self-limited • GI disease: single dose therapy of Mebendazole or Albendazole

Answer 9

caused by ascaris nematode | transient pulmonary infiltrates, dyspnea, dry cough, occasional fever, and eosinophilia

Answer 10

Sucks blood  A major cause of anemia worldwide (most prevalent in warm/humid areas)  Infection by one of 2 species: Ancylostoma duodenale and Necator americanus  Most risk: Children, pregnant/lactating women, women who menstruate heavily  Life Cycle • Eggs pooped out and larvae develop in soil  sit on grass  penetrate skin and enter bloodstream  larvae go to heart, lung capillaries, and alveolar spaces  get coughed up and swallowed  mature in the small intestine and can live up to 9 yrs-> eggs pooped and cycle continues

Answer 11

Cutting plates • 0.2-0.4 inches long • 5-10,000 eggs/day • Drinks .03 mL/worm/day  Need 25 worms to lose 1 ml blood/day

Answer 12

Teeth • 0.3-0.5 inches long • 10-30,000 eggs/day • Drinks 0.15 ml/worm/d  5 worms cause 1 ml blood/day loss • Secrete anticoagulants so more blood is lost

Answer 13

Ancylostoma duodenale - a hookworm

Answer 14

* Abd pain, wheezing, dsypnea, dry cough (usually a few days to weeks after infection) * Urticarial rash * * Fatigue due to iron deficiency anemia (chronic) * * If sensitized à papulovesicular dermatitis at entry site “ground itch” * If worms migrate laterally à cutaneous larvae migrans (especially dog and cat hookworms, as late as 2-8 wks after exposure to A. braziliense)

Answer 15

* Hookworm anemia in pregnancy causes: IUGR, Low birth weight/Stunting * Antenatal antihelminthics increase maternal hemoglobin and Infant birth weight/survival

Answer 16

• Mebendazole x3 or Albendazole once

Answer 17

whip worm  4cm long nematode; both intracellular and extracellular  Hair-like part contains the head(goes into epithelium); Wider posterior section has reproductive organs(protrudes into GI lumen)  Eggs take 2-4 weeks in soil to become infective;2-3 months to mature in humans  Make 0-20,000 eggs/day -- Eggs have bipolar plugs.  Fecal oral lifecycle • Eggs are ingested, larvae hatch and migrate to caecum where they mature • Large # worms can cause colitis mimicking IBD-- abdominal pain and diarrhea  Symptoms à • Usually asymptomatic • In heavy infections (because adults live primarily in cecum): o Loose and frequent stools with mucus, Tenesmus (the feeling one has to constantly defecate), blood o In heavily infected children: rectal prolapse  Treatment: ivermectin, mebendazole, or albendazole (1-3 days depending on severity)

Answer 18

 Has both free living and parasitic forms  Causes autoinfection/problems in immunosuppressed  Infection can last decades  Symptomatic: Diarrhea, abdominal pain, nausea, vomiting  LARVAE are shed in stool (not eggs) • RABDITIFORM LARVAE ARE EXCRETED IN STOOL  can either become free living adults, auto infect or become filariform larvae • Free living produce eggs, rabditiform hatch and become infective filarform larvae  penetrate skin • Autoinfection: rabditiform larvae in large intestine become filariform larve, penetrate intestinal mucosa or perianal skin and follow infective cycle • Cycle  filariform larvae enter circulatory system, go to lungs/alveolar spaces  coughed and swallowed into small intestine to become adults  adult female deposits eggs in intestinal mucosa  hatch and migrate to lumen as rabditiform larvae  excreted or autoinfection

Answer 19

• Immunocompromised state • Large burden of parasites • GI: Nausea, vomiting, abd. pain, diarrhea, many erosions due to millions of larvae in intestinal mucosa • Pulmonary: diffuse infiltrates, wheezing, dyspnea, cough with hemorrhage, pneumonitis, and edema • Neurologic: gram negative polymicrobial meningitis • Systemic: fever, hypotension àgram negative sepsis  Clinical clues – abdominal discomfort, wheezing, eosinophilia  Diagnosis • Stool o/p isn’t good due to : low worm burden, low/irregular egg production, and uneven distribution • So…multiple stools on multiple days (time from infection to shedding of larvae is 3-5 weeks) • Examination for larvae on duodenal aspirate via endoscopy  Treatment  Ivermectin, Albendazole, or Thiabendazole

Answer 20

o Paracapillaries (Capillaria) philippinens –

Answer 21

 Like Strongyloides, can autoinfect  Symptoms: • Often initially asymptomatic  watery diarrhea, abdominal pain, and often death • Over time develop: Borborygmus, Abdominal pain, Watery diarrhea  If not treated over weeks to months get large electrolyte losses and dehydration which can lead to death  Pathogenesis: • Eat infected raw fish • Larvae released into intestine  Grow to adults which burrow in mucosa • Female worms lay eggs (oviparous); Some female worms are larviparous  into stool • Some larvae burrow into the intestinal lining and develop into adults • Over time the worm burden increases (from a few to thousands) and symptoms progress  Diagnosis: stool o/p (eggs similar to Trichuris)  Treatment: 10 d course albendazole + supportive Rx (IVF, replete electrolytes, etc.)

Answer 22

o Pinworm (Enterobius vermicularis)

Answer 23

common in TEMPERATE areas  Kids>adults; causes peri-anal ITCHING  Humans are the only host --> fecal/oral transmission  Diagnosis  early am, before showering or defecating, ”Scotch tape test” tape side down on slide • Stool O/Ps not very helpful  Treatment = Mebendazole, pyrantel pamoate, or ivermectin • Treat all members of households and repeat in two weeks to prevent reinfection • Careful trimming of fingernails, handwashing, washing of bedclothes to rid house of eggs

Answer 24

o In areas where helminth infections are common, usually people are infected with MULTIPLE helminth species

Answer 25

o Consider in cases of unexplained abdominal pain, nutritional deficiencies, rash, or eosinophilia in immigrant or traveler.

Answer 26

stool O&P (OVA & PARASITE) x 3 , plus Strongyloides serology o Would empirically treat immigrants (and long-term travelers) with ivermectin prior to immunosuppression to prevent possibility of Strongyloides hyperinfetion.