Helminthic Parasites

Diphyllobothrium Latum (fish tapeworm): Pathology

-Asymptomatic -Intestinal disturbances: colic, hunger pains, nausea, vomiting, diarrhea & loss of appetite. Intestinal obstruction. -Neurological manifestations: e.g. headache, insomnia & convulsions. -Anemia

Clonorchis Sinesis: Pathology

-Asymptomatic, only eggs can be found in the feces -Eating raw or under-cooked fish -Hatches in the host small intestine -Infective stage: metacercaria in fish -Infective route: oral consumption -Due to: >Inflammatory reaction in the biliary epithelium >The wall of the bile ducts thickened -Intrahepatic bile ducts expansion, hepatomegaly, necrosis of liver tissue -Continuous severe infection may cause liver cirrhosis = portal hypertension result in upper gastrointestinal bleeding, and Pancreatitis -Associate with hepatic carcinoma -Severe infections: symptoms are similar to viral hepatitis, hepatomegaly, person with heavy worm loads may suffer from biliary angina.

Chronic Schistosomiasis

-Asymptomatic: most people are asymptomatic -Symptomatic: the most common syndrome is abdominal pain with intermittent diarrhea. -Hepatosplenomegaly

Echinococcus Granulosus: Pathology

-Causes hydatid disease: >Larvae invade the circulatory system and travel throughout the body >Form hydatid cysts >Symptoms of hydatid disease follow enlargement of cysts in infected tissue and result from tissue dysfunction >Large numbers of hydatid cysts can be fatal >If cysts rupture, parasite can rupture throughout body. If exposed immediately, can put body into shock. -Prevention: Good hygiene practices and avoiding fecal-oral transmission from infected pets. Limit contact with infected animals (dogs). -Symptoms: Depending where the infection is, the symptoms can differ: head = dizzy etc.

Clonorchis Sinesis: Information

-Chinese liver fluke -Cause "clonochoriasis" -A common trematode in the Far East -3rd most common parasite in the world -Lives in the liver, can be found in bile duct -Requires THREE hosts -Intermediate host: snail and fish -Definitive host: human -Reservoir host: dog, cat, etc. -Residing: hepatic bile duct -Discharge of eggs with feces

Schistosomiasis Prevention

-Control of the source of infection: >Treat the patients and domestic animal at the same time. -Cut off the route of transmission: >Snail control >Sanitary disposal of human excreta -Protect of susceptive people: avoid contact with schistosome-infected water

Schistosoma (blood flukes): Pathology

-Dermatitis may occur at the site where cercariae entered -Infections can become chronic and can be fatal -Prevention: relies on improved sanitation and avoiding contaminated water -Schitosoma japonicum inhabits the blood -The basic pathologic lesion is the egg granuloma in the liver and colon -Acute schitosomiasis: fever, enlargement and tenderness of the liver, eosinophilia, and dysentery -Late stage: giant liver and spleen

Schistosoma (blood flukes): Information

-Dioecious blood flukes -Causative agent of schistosomiasis -Intermediate host: snail -Humans are the principal definitive host -Will see blood in urine. Sign there were snail host, larvae penetration. -Three geographically limited species infect humans >S. mansoni >S. haemotobium >S. japonicum -Cercariae burrow through skin of humans who contact contaminated water -Larvae mature and mate in the circulatory system -Eggs move to the intestines or the urinary bladder and ureters

Trematodes

-Flukes are flat, leaf-shaped worms -Intermediate host: usually a snail -Lack complete digestive systems -Oral and ventral suckers enable attachment to host tissues to obtain nutrients -Geographical distribution is limited because the intermediate host is limited -Grouped according to the site in the body they parasitize Ex. By lung = lung fluke Ex. By liver = liver fluke

Taenia: Information

-Intermediate hosts: cattle, swine -Intermediate hosts become infected by eating contaminated vegetation. -Humans living close to livestock have the highest incidence of infection. -Humans ingest cysticerci in raw or under-cooked meat. -Adults attach to the intestinal epithelium.

Terminal Stage of Schistosomiasis

-Liver cirrhosis is the prominent syndrome of this stage -According to the manifestations , it can be divided into different types: >The type of giant spleen >The type of ascites (accumulation of protein-containing (ascitic) fluid within the abdomen. )

Acute Schistosomiasis

-Mainly occurs during July to September -The history of contact with schistosome-infected water. -Schistosome dermatitis (swimmers itch) -Incubation period: average 1 month -Clinical manifestations begin 4 to 8 weeks of infection, similar to the time from egg to adult worm (40 days) -Fever: intermittent, maintain weeks to months -Allergic reaction: enlargement of lymph nodes and eosinophilia -Digestive syndromes: abdominal pain, diarrhea with pus and blood, constipation or diarrhea -Hepatosplenomegaly

Taenia: Pathology

-Most individuals shed proglottids without experiencing symptoms (asymptomatic) -Blockage of the intestine can occur if the tapeworm is large. -Prevention: Thoroughly cooking or freezing meat is the easiest method

Ectopic Lesion of Schistosomiasis

-Schistosomiasis in lungs: >found in acute schistosomiasis, by egg deposition. Symptoms are light and signs are not clear -Schistosomiasis in brain: >Acute type: encephalomeningitis >Chronic type: focal epilepsy

Schistosoma (blood flukes): Epidemiology

-Source of infection: humans and mammals (especially cattle) infected by schistosome -Must have intermediate host in the environment to infect others -Susceptibility : everyone is susceptive. -Especially peasant and fisherman -Route of transmission: three major factors* are responsible for the occurrence of schistosomiasis

Echinococcus Granulosus: Information

-Tapeworm of canines -Intermediate host: humans are accidental -Canines are infected by eating cysticerci in various herbivore hosts. -Infections occurs by consuming food or water contaminated from dog feces

Three Major Factors for Schistosoma:

1. The method of disposal of human waste 2. The presence of the snail intermediate host 3. The contact with cercaria-infected water

What are the three groups of helminths?

Cestodes-tapeworms aka "flatworms" Trematodes-flukes (looks like a leaf) Nematodes-roundworms (tapered end)

How do we get cestodes in our system?

Eggs passed onto intermediate host (ex. pigs) by ingesting the contaminated food. Eggs will hatch into larvae, penetrating intestinal wall and migrate to other tissues. Humans ingest raw or under-cooked contaminated meat.

Helminths

Macroscopic, multi-cellular, eukaryotic worms. Reproductive systems and life cycles are complex. Intermediate hosts are often needed to support larval stages. Adult worms are either dioecious or monoecious. Dioecious worms have male and female sex organs in separate worms. Monoecious worms have both sex organs. -High amount of eosinophil, probably has some parasitic worm

Cestodes

Most notorious. All tapeworms lack digestive systems. All possess the same general body plan: head, hook, sucker Proglottid - male and female

What are the two types of tapeworms?

Taenia saginata is the beef tapeworm. Taenia solium is the pork tapeworm.