Giardiasis, Helminths, Hookworms, Tapeworms, and More PDF

· Giardiasis o Causative agent § Giardia Lablia, a flagellate protozoan § AKA giardia intestinalis and giardia duodenalis o Risk factors § Travel to endemic areas § Recreation or wilderness travel (backpacker’s diarrhea): common in lakes,...

· Giardiasis o Causative agent § Giardia Lablia, a flagellate protozoan § AKA giardia intestinalis and giardia duodenalis o Risk factors § Travel to endemic areas § Recreation or wilderness travel (backpacker’s diarrhea): common in lakes, etc. o Local outbreaks § Contaminated drinking water § Daycare centers o Signs/Symptoms § 50% will have none § When present, symptoms could include: · ABD cramps, bloating, flatulence · Steatorrhea, frothy, greasy foul smelly diarrhea · Occasionally malabsorption and weight loss · Diarrhea can become chronic o Diagnosis § Stool antigen test (preferred) § Stool microscopy o Treatment § Oral rehydration § Tinidazole is preferred if > 3 years old § Nitazonaxide if 1-2 years old § Metronidazole if < 12 months old · Helminths o These worms are highly prevalent and, depending on the species, may exist as free-living organisms or as parasites of plant or animal hosts o Most of these infections are restricted to nonhuman hosts, and only rarely do these zoonotic helminths accidentally cause human infections · Hookworms o Causative agents § Ancylostoma duodenale § Necator americanus o Transmission § Human fecal contamination of soil o Pathophys § Larvae penetrate the skin (usually the feet) and migrate to the pulmonary capillaries. They are carried to the mouth via the mucociliary escalator and swallowed. They mature inside the small intestines, where they attach to the intestinal lumen to feed on blood o Clinical manifestations § Phase 1 itching on site of entry (generally feet)  § Phase 2 transient pneumonitis (mild dry cough, wheezing, low grade fever) · Loeffler’s syndrome also possible § Phase 3 GI symptoms – N/D, epigastric pain, abd peristalsis § Phase 4 anemia and hypoalbuminemia on labs o Diagnosis § Stool microscopy (Kato-Katz technique) § Abnormal labs · Eosinophilia · Increased IgE · Iron deficiency anemia · Positive Guaic o Treatment § Albendazole is the preferred treatment § Mebendazole is 2nd line § Iron supplementation may be necessary if the patient has iron deficiency anemia · Tapeworms o The 4 major tapeworms that cause noninvasive infections in humas are: § Taenia saginata – the beef worm § Taenia solium – the pork worm § Diphyllobothrium latum – the fish worm § Hymenolepis nana – the dwarf worm o Beef tapeworm § Taenia saginata § Risk factors · Undercooked beef § Symptoms/signs · Most carriers are asymptomatic · May sense movement of the worm through the anus or pass them in stool o Pork tapeworm § Taenia solium § Risk Factors · Undercooked pork · Tropical/resource limited countries § Symptoms/signs · Most carries are asymptomatic · Possible abd pain or diarrhea · Neurocysticercosis o Caused by ingesting T.solium eggs o In the intestines, the egg releases an oncosphere that can cross the gut wall and enter the blood  o Larvae can encyst in different human tissues including the skin, muscle, kidney, heart, liver and brain. The lesions this causes are called cysticerci o Cysticerci in the brain cause inflammation and scarring, often leading to seizures · Diagnosis and treatment of cestode infections o Diagnosis § T. saginata (beef) · Stool microscopy § T. salium (pork) · Stool microscopy · Antibody tests/MRI if neurocysticercosis suspected o Treatment § T. saginata (beef) · Praziquantel § T. salium (pork) · Albendazole or praziquantel · Consider treatment with anticonvulsants if having seizures · Ascariasis o Giant roundworm infection o Causative agent § Ascaris lumbricoides o Clinical findings § Small worm load: usually asymptomatic § Large worm load: vague abd symptoms § High worm load: intestinal obstruction, pancreatic or bile duct obstruction o Pneumonitis § Early stage larvae migrating through the lungs may induce an inflammatory response § Symptoms bronchial spasms, mucus production o Loeffler’s syndrome § Fever, cough, wheezing, dyspnea, lung infiltrates, eosinophilia, elevated IgE antibodies o Diagnosis § Stool ova § Parasites exam § Can be made clinically on the basis of worms emerging from the mouth, nose or anus o Treatment § Albendazole or mebendazole · Enterobiasis (pinworms) o Causative agent § Enterobius vermicularis o Epidemiology § Maximum prevalence in school aged children  o Life cycle § Eggs hatch in the duodenum and larvae migrate to the cecum § Females mature in about a month and remain viable for about another month § During this time they migrate through the anus to deposit large numbers of eggs on the perianal skin o Symptoms § Most individuals with pinworm infection are asymptomatic § The most common symptom is perianal pruritus, particularly at night, due to the presence of the female worms or deposited eggs o Diagnosis § Made by finding adult worms or eggs on the perianal skin § Cellophane tape test or pinworm paddle test § Common test is to apply clear cellophane tape to the perianal skin, ideally in the early morning, followed by microscopic examination for eggs o Treatment § Albendazole or mebendazole § Pyrantel if pregnant § Other family members with infection should be treated concurrently, and treatment of all close contacts may be appropriate when rates of reinfections are high in family, school, or institutional settings · Trichinosis (trichinellosis) o Causative agent § Trichinella spiralis § Other trichinella species o Transmission § Raw or undercooked meat, commonly pork o When infected raw meat is ingested, trichinella larvae are freed from cyst walls by gastric acid and pass into the small intestine o The larvae then invade intestinal epithelial cells, develop into adults, and the adults release infective larvae. These parasite travel to skeletal muscle via the bloodstream. They invade muscle cells, enlarge, and form cysts o Clinical manifestations § GI phase abd pain, N/V/D § Muscle phase myalgias, fever, swelling of the eyelids, hemorrhages of the retina and conjunctiva, subungual splinter hemorrhages, myocarditis, encephalitis, meningitis, and PNA are possible o Diagnosis § Anit-trichinella antibodies § ELISA/Western blot