Introduction to Parasites (Habal) Flashcards
Neurocysticercosis - Taenia solium
This parasite is more common in male homosexuals and poorly sanitized environments, is prevalent in the tropics, and is obtained through fecal-oral transmission.
Entamoeba histolytica
The species of Trypanosoma is found in the Americas, mainly central and South, emphasis on South.
T. cruzi
Echinococcus granulosus
This form of Leishmania is the most common. It causes relatively benign self-healing lesions. What is it and how would you treat it?
Cutaneous Leishmaniasis
Sodium stibogluconate
Ascaris lumbricoides
This parasite is common in tropical countries. It causes infection through ingestion or larval penetration of skin. Diagnosis is of larva in stool. Clinical manifestiations include itching, wheezing (pneumonia), diarrhea, weight loss.
Strongyloides strocrailis
Romana’s sign - T. cruzi
This parasite is found world-wide in lakes, streams, etc. Risk factors for infection via fecal-oral transmission include contact with domestic and wild animals, camping, and places such as prisons, day cares, and mental health institutions.
Giardia lamblia
Ring-enhancing lesions on brain caused by Toxoplasma gondii
This type of parasite can reproduce in high numbers, leading to many organisms that can obstruct parts of the body, leading to clinical manifestations.
Roundworms - nematodes
T. bruci - enlarged lymph node (Winterbottom’s sign)
Found in sub-Saharan Africa and transmitted by the Tse Tse fly, this parasite causes local inflammation at the site of infection, including swollen lymph nodes. It can cross the blood brain barrier, resulting in CNS involvement that manifests in symptoms such as somnolence and confusion. What is the available treatment for this?
T. bruci
Suramin
Taenia saginata
Adult worm appears yellow with dark markings and grow anywhere from 3-15 m in length. Scolex has 2 sucking grooves. Crustaceans eat eggs found in fresh water. Humans eat these crustaceans, ingesting the eggs, which then become larvae, and then adults which can then lay eggs. Definitive hosts are humans and dogs. Transmission is ingestion of raw, undercooked fish.
Diphyllobothrium latum - fish tapeworm
This protozoa of the Apicomplexa superphylum is a zoonotic, opportunistic parasite. Its definitive host is the domestic cat; vertebrates are the intermediate host. Immunocompromised individuals are at a greater risk of infection, as is the fetus if the mother acquires the infection during gestation.
Toxoplasma gondii
Life cycle of this parasite always includes at least one intermediate host that is a snail.
Trematodes
45 y/o immigrant from Mexico presents with hydrocephalus, motor spasms, paraplegia, loss of vision. He has a history of chronic meningitis. X-Ray shows many holes in brain. What’s wrong with him?
Neurocysticercosis - caused by Taenia solium
This parasite causes infection from soil contaminated with human feces. The adult worm inhabits the cecum and large intestine. Light infections are asymptomatic while heavy infetions cause tenesmus, malnutrition, and diarrhea. In severe cases, you may encounter rectal prolapse.
Trichuris trichiura - whipworm
This species of helminths has a segmented plane, is hermaphroditic, and has an oral sucker, botridias, and double Rostellar hooks.
Cestodes
This species of helminths has an unsegmented plane, has a digestive tube that ends in the cecum, is hermaphroditic (except for Schistosoma, which are dioecious), and has both oral and ventral suckers.
Trematodes
Strongyloides strocrailis
This parasite, which is transmitted by the Reduviid kissing bug, is found in rural and poor areas of Central and South America. Upon infection, the parasite invades macrophages, creating a chagoma.
T. cruzi
This parasite is transmitted by the sand fly and reproduces inside macrophages.
Leishmania
What are the 6 species of Leishmania?
L. donovani
L. tropica
L. major
L. aethiopica
L. mexicana
L. brazilliensis
Echinococcus granulosus
This is the most common tapeworm in the US. It is the only human tapeworm to complete its cycle in one host; both larval and adult forms can be found in man. It can be directly transmitted through ingestion of eggs that hatch in the duodenum or indirectly transmitted through ingestion of infected arthropods. What is it and how would you treat it?
Hymenolepsis nana
Praziqantel
This is one of the largest and most common nematodes in the world. Infection is from soil contaminated with human feces and often occurs when parasite eggs are ingested in undercooked meat. Females produce about 200,000 eggs daily, causing the massive amount of worms that can grow and cause bodily obstructions.
Ascaris lumbricoides
This parasite only infects humans. Male and female worms inhabit the colon; female worms migrate to perianal region at night to lay eggs. Diagnosis is made using the scotch tape test. What it this and how would you treat it?
Enterobius vermicularis - pinworm
Albendazole
Hand washing
This single-celled protozoa that uses flagella to move uses humans and animals as a reservoir and leaves cysts, which can survive in water up to 3 months, in their feces. Symptoms include watery, foul smelling diarrhea, nausea, and weight loss. It is often associated with areas of chronic conditions and stagnant or slowly-moving water that has been contaminated by animal feces.
Giardia lamblia
Using a string test, you identify in your patient a parasite that is known for its pear-shaped trophozoite with 2 prominent nuclei, a ventral sucking disk, and 4 pairs of flagella. Its cyst, which is the infective stage, has 4 nuclei and is passed through the stool. What is this parasite, and what treatment would you choose?
Giardia lamblia
Metronidazole
This parasite causes infection via ingestion of raw or undercooked pork. It has a scolex with 4 suckers and a circle of hooklets. Humans can serve as definitive or intermediate hosts.
Pork tapeworm - Taenia solium
Also, what is the distinguishing feature of this organism?
Trypanosoma (Trypomastigote)
Kinetoplast - DNA inside the mitochondria
This parasite is found in dogs (definitive host) and sheep; hunters and sheppards are most at risk. It has a scolex with 3 proglottids, a rostulum, 4 suckers, and 2 rows of hooks. It is one of the smallest tapeworms, and it sheds proglottids in feces.
Echinococcus granulosus - dog tapeworm
Infection by this parasite is associated with ingestion of cysts in undercooked pork or bear meat. Diagnosis is made via encysted larva in striated muscle. Clinical manifestations include gastroenteritis, fever, muscle pain, periorbital edema, and eosinophilia.
Trichinella spiralis
This parasite, caused by fecal-oral or food and waterborne transmission, causes chronic, self-limiting non-bloody diarrhea in immunocompetent individuals, but may last as long as 4 months in HIV patients or cause focal neurological deficits, retinochoroiditis, or pnumonia in the immunodeficient patient. Affected newborns may have hydrocephalus, hepatosplenomegaly, jaundice, fever, anemia, and/or pneumonia.
Toxoplasma gondii
This form of Leishmania cuases simple skin lesions that metastzsize to mucosae, especially in the nose and mouth regions. What is it and how would you treat it?
Mucocutaneous Leishmaniasis
Sodium stibogluconate
Trypanosoma cruzi
The organism in which the parasite develops is called the?
Intermediate host
This parasite causes infection due to ingestion of raw saltwater seafood. Symptoms include gastroenteritis, eosinophilia, and presence of occult blood in stool.
Anisakis
The non-motile, membrane-protected form of protozoa that is in the infective stage is called the?
Cyst
Entamoeba histolytica trophozoite
Patient presents with hydatid cysts in the liver that you’re worried may travel to the brain. Patient is mostly asymptomatic, but knowing what this organism could be you worry about leakage or rupture of these cysts that could result in anaphylactic reaction (fever, hypotension). What is this parasite?
Echinococcus granulosus
Pathogenesis of this parasite is as follows:
Ingestion of food/water contaminated with eggs - eggs hatch in small intestine - released juvenile larvae penetrate intestinal wall and get into portal circulation - larvae are carried to liver, heart, then lungs - larvae migrate through lungs to trachea - larvae are coughed up then swallowed back down to the intestine - larvae mature, mate, and complete cycle.
Ascaris lumbricoides
Describe what you might find in the cells of Entamoeba histolytica.
Trophozoites - single nucleus, ingested RBCs
Cyst - 4 nuclei (in stool)
This parasite is common in Africa and Central America. It is transmitted by the Black Fly. Clinical manifestations include subcutaneous inflammation and pruritus. If microfiliearage migrate to the eyes, they can cause “River Blindness.” What is this and what would you treat it with?
Onchocerca volvulus
Ivermectin
What are 2 filarila nematodes we discussed? What are they notorious for doing?
Wuchereria bancrofti & Onchocerca volvulus
Invade lymph, causing blockage of lymphatics
Ancyclostoma
The oocytes of this parasite are shed by its definititve host, the domestic cat. Exposure to cat feces, such as when cleaning the litter box, can lead to infection, which can be extremly harmful if caught by a pregnant woman as this parasite can cross the placenta.
Toxoplasma gondii
This species of Leishmania causes “Kala-Azar” fever - skin, lymph, bone marrow, spleen, and liver involvement. It causes a generalized infection of the reticuloendothelial system, hepatosplenomegaly, and has a high mortality. Which species is it and how would you treat it?
Visceral leishmaniasis
Sodium stibogluconate
The living carrier that transports the parasite from infected to non-infected host is called the?
Vector
This gastrointestinal protozoa is associated with diarrhea in the immunocompromised and fecal-oral transmission. Extremely low exposure to its oocytes via a source such as contaminated water supply will cause mild, self-limiting enterocolitis in the immunocompetent patient and extreme diarrhea and dehydration in the immunocompromised, particularly in AIDS patients. What treatment would you suggest?
Cryptosporidium parvum
There is no effective therapy; often lethal in AIDS patients
Patient presents with dilated cardiomyopathy, but no other acute symptoms. What parasite could be responsible for this? What fungus? What would you treat the parasite with?
T. cruzi
Coxsackie B
Nifurtimox
Female Anopheles mosquito transmits larva of this parasite most commonly in the tropics. Clinical manifestations include filarisasis and elephantiasis.
Wuchereria bancrofti
The metabolically active, usually motile stage of protozoa is called the?
Trophozoit
The host in which the mature or sexually mature parasite lives is called the?
Definitive host
Although most patients are asymptomatic, you may see abdominal dicomfort and cramping, as well as diarrhea and constipation cycles. Patients may also present with B12 deficiencies due to decreased uptake, which may then result in megaloblastic anemia. What parasite is this and how would you treat it?
Diphyllobothrium latum
Praziquantel, avoid undercooked fish, freezing fish
Life cycle of this parasite:
Human ingests fish infected by metacercaria - these excyst and develop into adults - adult gives eggs that when shed in human can form mericidia - these are taken up by a snail - leave snail as cercariae are free-swimming in water - finds sheep and encysts to form metacercaria (infective when ingested) - human ingests sheep, gets sick
Fasciola hepatica - sheep liver fluke
Enterobius vermicularis
Patient presents with flask-shaped ulcer, watery stools containing mucus and blood, and complaint of gradual onset of abdominal pain. You’re concerned that this ulcer may be deep enough to hit the blood supply of the intestinal wall, which would would allow the organism to disseminate into other organs and, potentially, the CSF. What does he have? What will you treat him with?
Entamoeba histolytica
Metronidazole
Taenia solium
Patient presents with megacolon and megaesophagus. No acute symptoms currently What parasite can cause this to occur?
T. cruzi
Entaboeba histolytica, Giardia lamblia, Cryptosporidium parvum, Trichomonas vaginalis, Microsporidia, Apicomplexa, Trypanosoma, Leishmania are all examples of what kind of protozoa?
Intestinal and tissue
This parasite’s trophozoites coat the distal villi, leading to malabsorption of food. Patients who are IgA deficient are predisposed to symptomatic infection.
Giardia lamblia
These types of parasites have a characteristic leaf-like appearance, ventral sucker, and oral opening. All are associated with free-swimming.
Trematodes - flukes
Entamoeba mature cyst
Life cycle of this parasite:
Human ingests fish infected by metacercaria - these excyst and develop into adults - adult gives eggs that when shed in human can form mericidia - these are taken up by a snail - leave snail as cercariae are free-swimming in water - finds fish and encysts to form metacercaria (infective when ingested) - human ingests fish, gets sick
Clonocrichis sinensis - Chinese liver fluke
Trypanosoma bruci
What do Taenia solium have that makes them particularly dangerous?
Cysticerosis stage - embryos can travel throughout body and then form a cyst. Symptoms will depend on where that cyst ends up. If it makes it to the brain, you’ll get neurocysticercosis - this is bad!
Name the phylum with the following characteristics: unicellular, aerobic, heterotrophic, present in areas with large water supply, asexual reproduction (via budding, schizogony, sexual means), and presence of cyst under adverse conditions.
Protozoa
Characteristics of this type of cestode include scolex (head), segmented body (proglottids), suckers, monocieous, and eosionphilia (increase IL-5).
Tapeworms
This parasite has larva that can penetrate skin. It attaches to the GI mucosa, causing blood and fluid loss. Clinically, it can manifest as microcytic hypochromic iron deficiency anemia, pot belly, finger clubbing, and pica. How would you treat it?
Ancyclostoma duodenale - hookworm
Albendazole
This parasite is most encountered in Asia, but has been found in other places around the world. Egg has a characteristic operculum. Adults are encapsulated in a granuloma, which can lead to what appear to be clinical manifestations of TB. Ruptured cysts produce cough and chest pain.
Paragonimus westermani
This parasite is found world-wide. It has a scolex with 4 suckers, but no hooks. Infection occurs by ingestion of cystceri in undercooked beef. Humans act as the host. What parasite is this and how would you treat it?
Beef tapeworm - Taenia saginata
Praziquantel, Albendazole
Life cycle:
Unembryonated eggs in water - embryonated eggs - miracidia hatch and penetrate snail - sporocytes, rediae, cerccariae - cercariae invade the crustacean and encyst into metacercariae - humans ingest inadequately cooked or pickled crustaceans containing metacercariae - excyst in duodenum - adults in cystic cavities in lungs lay eggs which are excreted in sputum; alternately eggs are swallowed and passed with stool
Paragonimus westermani
Ascaris lumbricoides
This species of helminths is cylindrical, has a body cavity, has a digestive tube that ends in the anus, is doecious, and has lips, teeth, filariform extremities, and dentary plates.
Nematodes
This species of Trypanosoma is found in Africa.
S. bruci
Entamoeba histolytica trophozoite
Patient presents with hemorrhagic/eosinophilic pneumonia, intestinal rupture, asthma, and urticaria. What parasite has infected the patient and how would you treat it?
Ascaris lumbricoides
Albendazole
This parasite is common world-wide, especially in warm, humid climates. It is characterized by a curved anterior end and a mouth containing large plates that can cut through intestinal wall.
Ancyclostoma
This parasite is a pathogenic amoeba that leads to invasive amoebiasis. Psuedopods allow it to move, and the contaminated water causes diarrhea in infected persons.
Entamoeba histolytica
