Exam 3: Lect 2 Flashcards
Roundworm: Nematode
Ascaris lumbricoides: Location
- World wide distribution
- Most common human helinthic infection
- Highest tropical and subtropical
- Areas of inadequate sanitation
- Rural areas of SE-USA
Roundworm: Nematode
Ascaris lumbricoides: Symptoms
- Acute Ascaris intestinal obstructiion is a leading cause of a “surgical abdomen” in children
- Low adult worm burden can be asymptomatic
- High burden:
- Abdominal pain, obstruction
- Hepatobilary Ascariasis (HPA): adult worms block bilary tract, hepatic abscess, appendictis, blockage, secondary infections, death
- Migratory Phase of infection (lung):
- Can cause;
- Cough (produce worms), dyspnea, hemoptysis
- Loeffler’s syndrome - eosinophilic pneumonitis, resembles asthma
- Malnutrition and “failure to thrive” due to food absorption by the worm
Roundworm: Nematode
Ascaris lumbricoides: Treatments
- Migaratory (parenteral) phase of the infection is transitory, seldom diagnosed, and not typically treated
- Single dose therapy effective
- Heavy worm burden resulting in pneumonia like sydrome is treated with corticosteroids
- Surgical intervention if intestinal or biliary obstruction as necrosis of intestinal tissue will occur
- Adult worms removed endoscopically if needed
Roundworm: Nematode
Enterobius vermicularis (Pinworm): Location
- Worldwide
- Frequent in school or preschool children
- Crowded conditions
- More common in temperate than tropical countries
- Most common helminthic infection USA
- Direct life cycle spread by fecal oral route
Roundworm: Nematode
Enterobius vermicularis (Pinworm): Ova
- Collect early morning tape prep from perianal region
- 30 um by 50 um
- Thin, smooth, transparent shell
- Oval and asymmetrical - flattened side
- Contains developed larva
- Stool samples are not helpful
Roundworm: Nematode
Enterobius vermicularis (Pinworm): Adult worm
- Female 13 mm length 0.5 mm width, appear as small pieces of thread
- Thin flexible outer covering, fin-like expansion at anterior end, long pointed tail
Roundworm: Nematode
Enterobius vermicularis (Pinworm): Treatment
- US - pyrantel pamoate (over the counter option)
- Drugs cidal for eggs or devolpong larvae therefore:
- Retreatment 2 weeks after the original therapy destroys worms that have hatched from eggs ingested after the first treatment
- Eggs survive 2 to 3 weeks on clothing and bedding, occurs for limited period of time and one retreatment is required
Roundworms: Enterobius vermicularis (pinworm)
Pyrantel Pamoate, and Diethylcarbamazine
Sythetic drugs that bind to neurotransimitter recopteors, causing complete muscular contraction of helmiths
Roundworm: Nematode
Trichuris trichiura (Whipworm): Location
- Worldwide
- Increased numbers in areas with tropical weather and poor sanitation practices, and among children
- Trichuriasis - southern United States
- 3rd most common round worm of humans
Roundworm: Nematode
Trichuris trichiura (Whipworm): Symptom
- Secrete a pore forming protein that may play a role in anemia and diarrhea
- Adult worms do not feed directly on blood or other host tissues
- Frequently asymptomatic (low burden)
- Clinical disease mainly children:
- Bloody diarrhea, chronic colitis
- Tenesmus - straining to deficate -> long term leads to prolapse
- Heavy burden; chronic malnutrition, anemia, gastrointestinal problems, possible growth retardation/ failure to thrive
Roundworm: Nematode
Trichuris trichiura (Whipworm): Ova
- Barrel shaped, thick shelled, polar “plugs” at each end
- Unembryonated when passed in stool
Roundworm: Nematode
Trichuris trichiura (Whipworm): Adult worm
- Males: coiled posterior
- Females: straight posterior
- Both have a long whip-like anterior
- Adults reside in the large intestine, cecum, and appendix of the host
Roundworm: Nematode
Trichuris trichiura (Whipworm): Treatment
- Mebendazole with inferior alternative Albendazole
- Important to avoid in first trimester of pregnancy due to teratogenic (developmental defects) concerns with benzimidazoles
- Deworming campaigns childern under 6 months of age are also often not treated
Class: Benimidazole
- Inhibit microtubule formation and glucose uptake
- Albendazole
- Mebendazole
- Thiabendazole
- Triclabendazole
Hookworm: Nematode
Ancylostoma duodenale +
Necator americanus: Location
- 2nd most common human helminthic infection
- Both N. americanus and A. duodenale are found in Africa, Asia and the Americas
- Necator americanus predominates in teh Americas and Australia, while only A. duodenale is found in the Middle East, North Africa and Southern Europe
- Can Not differentiate species by ova examination
- Lifecycles are identical
- Adult worms are rarely found in stool samples
