PARASITIC DISEASES OF GIT Assistant Professor Dr. Syed Yousaf Kazmi

OBJECTIVES Major Parasites that cause GIT disease, their epidemiology, etiology, life cycle and pathogenesis Mechanism of transmission. Enlist clinical conditions Discuss the laboratory diagnosis of these infections

INTRODUCTION TO BASIC PARASITOLOGY Parasites are Eukaryotes Two major groups Protozoa (unicellular) Metozoa/Helminth (Multicellular)- worms Trophozoite -trophē=nourishment, zōon=animal (active feeding stage of a protozoal parasite) Cyst/ oocyst -inactive and infective form Protozoa-motility via pseudopods, flagella, cilia etc

INTRODUCTION TO BASIC PARASITOLOGY Helminths-worms Definitive host-which harbor sexual phase of parasite Intermediate host-which harbor asexual phase of parasite

LIST OF MAJOR PARASITES OF GIT PROTOZOA HELMINTHS Entamoeba histolytica Hookworms(Ankylostoma duodenale, Necator americanis) Giardia lamblia Ascaris lumbricoides Cryptosporidium parvum Strongyloides stercoralis Tinea saginata, Tinea solium Hymenolepsis nana Trichuris trichiura Diphylobothrium latum

Entamoeba histolytica Worldwide-common infection Trophozoites attach large gut Flask shape ulcers Mucus, epith cells, pus cells, amoeba pass in stool Acute-Extreme abd tenderness, dysentery, dehydration, incapacitation Subacute-Diarrhea, abd cramps, vomiting, desire to defecate, weight loss, general malaise Asymptomatic cyst passers E histolytica/dispar trophozoites E histolytic/dispar cyst

E histolytica-LIFE CYCLE & EPIDEMIOLOGY Feco-oral route Poor sanitation & hygiene Cyst ingested-contaminated water, veg, fruits, flies

Giardia lamblia Common pathogen of duodenum & jejunum Trophozoite heart shaped sucking disc-attachment to villi Does not invade, but attachment cause irritation, inflammation of duodenum/ jejunum Crypt hypertrophy, villous atrophy/ flattening, epith cell damage Giardia lamblia trophozoite Giardia lamblia cyst

Giardia lamblia-Pathogenesis Asymptomatic- if light infection Acute/ chronic diarrhea- in heavy infection Stool bulky, watery, semisolid, greasy, foul smelling- Mal-absorption Fatigue, weakness, weight loss, abd cramps, distention, flatulence-long period Symptoms intermittent in many cases Nutritional def e.g. iron def, folate def etc

Giardia lamblia- Pathogenesis Ingestion of cyst contaminated water, food Direct fecal oral route Cysts can survive for 3 months Drinking stream water during camping

Cryptosporidium parvum Protozoa of small intestine Immuno-compromised e.g. HIV inf- serious life threatening diarrhea Pathogen of rodents, monkeys, cattle, etc. Unrecognized cause of self limiting diarrhea in healthy Oocyst infective form Contaminated food/ water source of infection High vol stool like cholera Oocysts of C parvum modified ZN stain

Cryptosporidium parvum-Pathogenesis Oocysts- excystation of sporozoites-infect epith cells-released-infect other epith cells Whole life cycle within host Incubation period 1-12 d Diarrhea-large volume stool Cholera like pic in HIV, severe dehydration, shock and death Self limiting diarrhea in healthy Life cycle of C parvum

Ascaris lumbricoides Large worm, ♂&♀ Ingestion of eggs Larva hatch, heart lung cycle, reenters intestine-mature into adults Eggs passed in stool Eggs infective after 1 month till many months Very common world wide Poor sanitation & hygiene

Ascaris lumbricoides-Pathogenesis Pathogenesis is due to larval migration in lung-irritation, mucus production, wheeze (Loeffler’s syndrome) Adults-mechanical obstruction of gut, appendicitis, pancreatitis, Abdominal pain, vomiting, Anemia

HOOKWORM INFECTION Ankylostoma duodenale, Necator americanus Small 10 mm, ♂&♀ Female release up to 10,000 eggs/day Larva hatch in day or two, survive for several weeks in moist environment Penetrate intact skin of barefoot person, enter blood and undergoes heart lung cycle like Ascaris Adult reach intestine and attach to small intestine mucosa

HOOKWORM INFECTION-PATHOGENESIS Adult worm attach intestinal villi-buccal teeth Secrete anticoagulant and feed on blood Few hundred worms –blood loss and anemia Abdominal discomfort, diarrheoa, Ground itch Adult hookworm Ground itch

Strongyloides stercoralis Adult ♀ 2mm- parthenogenic Eggs passed in feces, larva develop into either infective or free living form Infective larva penetrate skin, heart lung cycle like Ascaris Adult form reach intestine In immuno-compromised-serious fulminant hyper-infection Severe diarrhea, abd pain, GI bleeding, nausea, vomiting Wheezing, hemoptysis, cough Chronic infection-many years Adult Strongyloides stercoralis with larva

Strongyloides stercoralis

TAENIA SAGINATA & TAENIA SOLIUM-Beef & Pork Tapeworm Humans eat "measly beef" or "measly pork" containing the bladder-like larvae called cysticerci- inf of T saginata and T solium, respectively Cysticerci develop in to adult-intestine May reach many meters Few problems, most asymptomatic Diarrhea and abdominal pain Egg-filled terminal segments break off-pass out with human feces-infective for cattle/pigs

Enterobius vermicularis Female pinworms about 10 mm in length Worldwide, mostly children perianal pruritus, especially at night female worms migrate down from the colon at night & lays egg-severe itch Scratching the anal region promotes transmission eggs are highly infectious within hours of being laid (hand-to-mouth transmission Irritability and fatigue from loss of sleep Ova of Enterobius vermicularis

Diphyllobothrium latum Fish tapeworm Enormous size, sometimes exceeding 10 m in length Eat improperly cooked or raw fish that is infected with the infective larvae known as plerocercoids Worm > 1 million eggs per day released Vague abdominal discomfort and loss of appetite Unusual capacity to absorb vitamin B12-deficiency leading to anemia

Hymenolepsis nana Dwarf tapeworm of humans Worldwide & one of the most common tapeworm infections in humans Direct human to human cycle Autoinfection common Massive infections, mostly in children Abdominal discomfort Most infections are asymptomatic Hymenolepsis nana ovum

LAB DIAGNOSIS OF PARASITIC INFESTATION OF GIT STOOL MICROSCOPY Most important and very cheap method of diagnosing parasitic infestation of GIT Naked eye examination-worm in stool e.g. Ascaris lumbricoides, Taenia saginata/solium etc. Blood, mucus in dysentery Wet film examination-motile trophozoites and cysts of Giardia lamblia, Entamoeba histolytica, RBCs, WBCs, ovum of hookworm, Ascaris , Taenia spp, etc Iodine stained examination-better visualization of cysts of Giardia, Entamoeba Modified ZN stain- Oocysts of Cryptosporidium

Tapeworm Hookworm ovum Taenia ovum E histolytica/dispar trophozoite Ascaris ovum Giradia lamblia trophozoite

LAB DIAGNOSIS OF PARASITIC INFESTATION OF GIT Upper GI Endoscopy Biopsy examination for Giardia, Cryptosporidium “Scotch tape” test for Enterobius vermicularis ovum Serological Tests ELISA for Giardia lamblia, Entamoeba histolytica etc. antigen detection