HELMINTH

HELMINTHTRANSMISSIONMORPHOLOGYCLINICAL FINDINGSDIAGNOSISTREATMENTIMAGES

Ascaris lumbricoides

1) Ingests eggs1) Adult attains a length of 20-30 cm.1) Asymptomatic in many individuals.2) Abdominal cramping. 3) Dry cough & fever while larvae are in the lungs.

4) Children may develop malnutrition as worms compete for food.1) Fecal exam for eggs2) Sputum exam may reveal larvae3) Eosinophilia1) Mebendazole: paralyzes worm & prevents it from migrating out of the small intestine to other organs.2) Albendazole (single dose)3) Ivermectin4) Nitazoxanide5) Pyrantel pamoate (safe in pregnancy)

Necator americanus (Hookworm)1) Larvae penetrate through skin1) Adult about 1 cm long.1) Diarrhea, abdominal pain, & weight loss.2) Iron deficiency anemia3) Itching @ site of skin penetration + rash4) Occasional cough with bloody sputum.1) Fecal exam for eggs (examine quickly, as eggs hatch rapidly).

2) Sputum exam may reveal larvae3) Eosinophilia1) Mebendazole2) Pyrantel pamoate3) Albendazole

Strongyloides stercoralis

1) Larvae penetrate thru skin2) Autoinfection1) Adult females 2 mm long.1) V/D, anemia & weight loss.2) Occasional fatal case caused by massive autoinfection (in IC host). 1) Fecal exam for larvae (no eggs!).2) Enterotest: swallow long nylon string later pull out may show larvae.

3) Sputum exam may reveal larvae.

4) Eosinophilia5) Ab & ag serum assay1) Ivermectin2) Albendazole3) Thiabendazole

Trichinella spiralis1) Ingestion of encysted larvae, often found in raw pork.1) Cysts in skeletal muscle.1) Fever, abdominal pain & diarrhea2) Muscle aches, as larvae migrate to skeletal muscle.

3) Severe cases: larvae migrate to ( & brain. 1) Look for microfilariae in blood drawn @ nighttime2) Biopsy3) Serology4) Tropical pulmonary eosinophilia:

1) Hypereosinophilia

2) ed levels of IgE

3) Granulomas within lymph nodes, spleen & lung1) Albendazole2) Mebendazole3) Thiabendazole4) Cook or freeze pork prior to consumption

Trichuris trichiura (Whipworm)

1) Ingest eggs

1) Eggs look like a football with polar bumps on each end. Adults whipshaped (3-5 cm long).1) Diarrhea2) Abdominal pain1) Mebendazole2) Albendazole

Enterobius vermicularis

1) Ingest eggs

1) Adult worms 1 cm long.

1) Severe perianal itching1) Mebendazole2) Pyrantel pamoate3) Albendazole

HELMINTHTRANSMISSIONMORPHOLOGYCLINICAL FINDINGSDIAGNOSISTREATMENTIMAGES

BLOOD AND TISSUE NEMATODES (ROUNDWORMS)

Onchocera volvulus1) Vector = black fly, which breeds in rivers & streams. Since cases cluster nearby, the disease is called river blindness.2) Found in Africa and Central & S. America.3) Reservoir = humans1) Filariae:

1) Threadlike adult roundworms.

2) Give birth to live offspring called microfilariae, which are transmitted via black fly. 1) Skin nodules: contain adult worms.

2) Allergic rxn to microfilarae migrating thru the dermis leads to: Pruritic rash with darkened pigmentation.

Lizard skin: intraepithelial granulomas, resulting in thick, dry, scaly skin.

3) River blindness: microfilaria emirate thru the eye. A marked inflammatory response can occur upon their death, which can lead to blindness. 1) Biopsy of advancing edge of rash1) Ivermectin: kills microfilarial stage only, and prevents them from leaving the uteri of adult worms.2) Doxycycline (kills endosymbiont Wolbachia).3) Alternative: diethylcarbamazine (but er toxicity than ivermectin).

4) Excise adult worms in nodules.

Wucheria bancroftiPacific Islands & Africa

Brugia malayiSE Asia1) Vector = mosquito (transmits microfilariae)1) Filariae:1) Threadlike adult roundworms.2) Give birth to live offspring called microfilariae.1) Filarial fever: febrile episodes associated with headache & swollen lymph nodes.

2) Elephantiasis: following repeat infections, fibrous tissue forms around the dead filariae that accumulate within the lymph nodes. This fibrous tissue plugs up the lymphatic system, resulting in swelling of the legs and genitals. Thick, scaly skin covers the edematous lower extremities, giving the appearance of elephant legs.

3) Tropical pulmonary eosinophilia: hypersensitivity rxn that causes bouts of wheezing & coughing, associated with hypereosinophilia. 1) Serology2) Eosinophilia1) Diethylcarbamazine2) Doxycycine (kills endosymbiont Wolbachia).

Dracunculus medinensis

Guinea worm1) Larvae within African, Middle Eastern, & Indian freshwater copepods (tiny crustaceans) are ingested when drinking freshwater.

2) Larvae pentrate the intestine & mature beneath the skin.1) Filariae;1) Threadlike adult roundworms: the female can grow to 100 cm in size.

2) Adult female pokes a loop of her body thru the skin, exposing her uterus.

3) When her uterus is exposed to water, 1000s of microfilariae are released. 1) Allergic symptoms occur during the release of microfilariae: N/V, hives & breathlessness.1) Demonstration of eggs in stool or urine samples2) Eosinophilia3) Ultrasound of the liver will dx liver disease1) Drive a small stick under the part of the worms body that is looped out of the skin. The stick is slowly twisted each day to pull out the 100 cm Dracunculus.

Cutaneous larva migrans (commonly Ancyclostoma braziliense dog hookworm)1) Occurs in SE US1) Larvae of dog & cat tapeworms.1) Creeping eruption: larvae of dog & cat hookworms penetrate the skin & migrate beneath the epidermis (a few cm per day). A raised, red, itchy rash moves with the advancing larvae. 1) Fecal exam for eggs or gravid proglottids.2) CT scan or biopsy of brain or muscle may reveal calcified cysticeri3) Eosinophilia occurs with cysticercosis1) Ivermectin2) Albendazole

Visceral larva migrans (MCly Toxocara canis dog roundworm)1) Ingestion of eggs1) Larva of dog roundworms, which CAN NOT mature in human. Toxocariasis;1) Migration of larvae thru the body results in fever, diarrhea, wheezing, hepatitis, & visua loss (from chorioretinitis).1) Fecal exam for eggs or gravid proglottids1) Albendazole2) Mebendazole

HELMINTHTRANSMISSIONMORPHOLOGYCLINICAL FINDINGSDIAGNOSISTREATMENTIMAGES

PLATYHELMINTHS (FLATWORMS)

Schitosomes

Schistosoma japonicum

Schistosoma mansoni

Schistosoma haematobium

1) Penetrate thru exposed skin.2) Since the eggs must reach freshwater to hatch, schistosomes cannot multiply in humans.3) Intermediate host = fresh water snail. Trematodes:

1) Eggs2) Mature larvae (called cercariae)3) Male & female adults

Schistosomiasis:

1) Pruritic skin rash @ site of penetration.

2) Acute schistosomiasis (Katayama fever): Intense transient itching Weeks later: fever, hives, headache, weight loss, cough (lasts about 3 wks). 3) Complications caused by immune rxn against eggs released by adults hanging out in the veins surrounding the intestine or bladder:

1) Liver: fibrosis of portal venous system leads to portal HTN.

2) Lung: fibrosis of pulmonary arterioles can lead to pulmonary HTN.

3) Intestine: deposits of eggs lead to inflammatory polyps.1) CT scan or ultrasound reveals cysts in the liver or lung.2) Serology1) Praziquantel: results in immediate exacerbation of symptoms, followed later by improvement.

2) Control: disposal of human fecal waste & destruction of intermediate host (snail).

Taenia solium (Pork Tapeworm)

1) Ingest undercooked pork containing larvae stage.

2) Ingestion of eggs: results in cysticercosis.Cestodes:

1) Scolex: head with hooks.2) Gravid ploglottids: contain eggs & uterus has < 15 pairs of lateral branches.

3) Cysticercus: round, fluid-filled bladder with the larval form within.

4) Adult can grow to 2-8 m. 1) Intestinal infection is usually asymptomatic.2) Cysticercosis: eggs hatch within the small intestine, and larvae travel to muscle, CNS &/or the eye, where they eventually form calcified cysts that are inflammatory.1) Blindness2) Neurologic manifestations: seizures, focal neurologic deficits, hydrocephalus blockage of CSF drainage. 1) Praziquantel & albendazole2) 2nd choice for all tapeworms: niclosamide

Taenia saginatum (Beef tapeworm)1) Ingest undercooked beef containing larvae stage.1) Scolex: head with suckers (but NO hooks).2) Gravid ploglottids: contain eggs & uterus has more than 15 pairs of lateral branches.

3) Can grow to 10 m in length1) Usually asymptomatic2) Occasionally develop abdominal discomfort, weight loss & diarrhea.1) Praziquantel

Diphyllobothrium latum (Fish Tapeworm)1) Ingest larvae in raw freshwater fish.2) Copepods (crustacean) ingests larvae which is then ingested by fish.

3) Grow into adult tapeworms1) Can grow to 45 m in length.1) Nonspecific abdominal symptoms2) Vitamin B12 deficiency leading to anemia.1) Praziquantel

Hymenolepsis nana (Dwarf Tapeworm)1) Ingest fertilized eggs2) Auto-infection1) Adults: 15-50 mm.2) Eggs are infectious.1) Usually asymptomatic2) Occasional abdominal discomfort, N/V.

1) Praziquantel

Echinococcus (Hydatid Disease)1) Ingestion of fertilized eggs1) Hydatid cysts: form most often in the liver & lung. The cysts enlarge over 1-20 yrs, producing symptoms by mass effect. These cysts can calcify.

Liver: abdominal pain 1) Surgical removal of cysts: extreme caution leakage of cystic fluid can induce a severe anaphylactic rxn. 2) PAIR- Percuatneous, Aspiration, Infusion of scolicidal agent, and Reaspiration.

3) Albendazole or Mebendazole are used adjunctively.