This small nematode lays sticky eggs at night. Eggs are flattened on one side.
Enterobius vermicularis
Gravid female worms migrate to the parianal region of the patient at night and lay eggs.
Enterobius vermicularis
This adult nematode is characterized as having alae (wings) at the side of the head.
Enterobius vermicularis
This very large nematode is acquired by direct hand-to-mouth infection (patient eats it).
Ascaris lumbricoides
The correct method of diagnosis of this nematode is the scotch tape preparation.
Enterobius vermicularis
True/False. Ascaris lumbricoides eggs are swallowed, the eggs hatch and the worms mature and live by eating intestinal contents.
FALSE. Ascaris lumbricoides eggs hatch, the larvae penetrate the intestinal lining, migrate through the lungs while maturing, ascend the bronchial tree and are swallowed. The adults now live in the lumen of the intestine.
This nematode "sews" its anterior end into the intestinal wall.
Trichuris trichiura
This nematode attaches itself to the intestinal villi by biting with semi-lunar cutting plates.
Necator americanus (hookworm)
This nematode attaches itself to the intestinal villi by biting with fang-like teeth.
Ancylostoma duodenale (hookworm)
This nematode has a complicated life cycle that features a free living option and an autoinfective option in addition to its parasitic life cycle.
Strongyloides stercoralis
This nematode infection is often diagnosed by detecting rhabditiform larvae in the stool.
Strongyloides stercoralis
This female nematode is parthenogenic and burrows into the intestinal wall to lay eggs.
Strongyloides stercoralis
This larval nematode is the cause of visceral larval migrans. Name the genus and species.
Toxocara canis or Toxocara cati
This larval form of this nematode is the cause of cutaneous larval migrans or creeping nematodes. Name the genus and species.
Ancylostoma caninum (dog hookworm), or any non-human hookworm. The larvae are "lost" and wander under the skin.
This nematode infection is acquired by eating the raw or poorly cooked flesh of mammals. The larvae encyst in the muscle tissue of the human host. Name possible mammalian sources of this infection and name the genus and species of the parasite.
Trichinella spiralis (can also be acquired by eating poorly cooked pork or bear)
This filarial nematode is acquired by being bitten by mosquitoes.
Wucheria bancrofti
Brugia malayi
This filarial nematode is acquired by being bitten by a fly. Adults migrate across the eyeball.
Loa loa
Name the causative agent of elephantiasis.
Wucheria bancrofti
Brugia malayi
Name the genus and species of the filarial nematode that causes "River Blindness".
Onchocerca volvulus
Schotch tape "touch preps" are used to diagnose infections with this parasite.
Enterobius vermicularis
Eggs of this nematode are characteristically flattened on one side.
Enterobius vermicularis
Females of this species of nematode migrate to the perianal region, the uterus prolapses expelling all her eggs. The adult usually dies.
Enterobius vermicularis
This nematode infection can be spread to others in the elementary school or day care centers.
Enterobius vermicularis
Enterobius vermicularis was named by Linnaeus in 1758. Apparently it has been a recognized problem for a very long time.
Free chicken!
This nematode burrows into the intestinal lining. It can lay fertilized eggs which hatch and rhabditiform larvae are found in the stool.
Strongyloides stercoralis
This nematode can have a free-living life cycle where adults live in the soil.
Strongyloides stercoralis
This nematode has a complex life cycle that features free living adults in soil, direct penetration of human skin and parthenogenic females.
Strongyloides stercoralis
What is the infective stage of Ascaris lumbricoides?
Egg
Which nematode can cause physical obstruction of the intestine?
Ascaris lumbricoides
Which nematodes migrate through the lungs?
Ascaris lumbricoides, hookworm, Strongyloides
What is the infective stage of Enterobius vermicularis?
Egg
What is the genus and species of the causative agent for pinworm?
Enterobius vermicularis
What is the specimen of choice for pinworm detection?
Scotch-tape prep. Clear tape only, not frosted.
Which nematode infection is characterized by intense itching in the perianal area?
Enterobius vermicularis
What is the infective stage of Ancylostoma duodenale?
Filariform larvae
What is the infective stage of Necator americanus?
Filariform larvae
What species of mammal(s) are associated with cutaneous larval migrans (common name)?
Dog and Cat
What is the causative agent of cutaneous larval migrans?
Filariform larvae of non-human hookworms.
Which nematode actively sucks blood from intestinal villi?
Hookworm (Necator americanus, Ancylostoma duodenale)
Anemia would be expected in which nematode infection?
Hookworm
What is the infective stage of Trichuris trichiura?
Egg
What is the genus and species of whipworm?
Trichuris trichiura
Which nematode can cause prolapse of the rectum?
Trichuris trichiura
Name the host of the nematode that encysts in muscle tissue. What is the nematode?
Pig (also bear).
Trichinella spiralis
What is the causative agent of River Blindness?
Onchocerca volvulus
Name the genus and species of the nematode that can crawl across the eyeball.
Loa loa
Name the genus and species of the nematode that can be acquired by eating poorly cooked pork.
Trichinella spiralis
Name the agent(s) of visceral larval migrans.
Toxocara canis, and T. cati
What is the definitive host of the nematode that causes cutaneous larval migrans?
Most often-domestic dog.
Name a protozoan infection that is associated with the genitourinary tract.
Trichomonas vaginalis
What is the infective stage of Giardia lamblia?
Cyst
Swimming in warm still-water lakes or ponds is associated with which protozoan infection?
Naegleria fowleri
What is the cause of Primary Amoebic Meningoencephalitis (PAM)?
Naegleria fowleri
Name a protozoan that can infect the brain.
Naegleria fowleri
What is the cause of amoebic dysentery?
Entamoeba histolytica
What infection may cause "flask-like" ulceration of the intestinal wall?
Entamoeba histolytica
Name the stage commonly involved in disease transmission of parasitic protozoa.
Cyst
Name the stage of parasitic protozoa that most often causes pathology and symptomatology.
Trophozoite
Charcot-Leyden crystals are associated with which infection?
Entamoeba histolytica
Which parasitic protozoan may be expected to have ingested RBCs?
Entamoeba histolytica
Entamoeba histolytica is most often transmitted by?
Fecal-oral route
Name the genus and species of the protozoan flagellate that is considered to be a sexually transmitted disease?
Trichomonas vaginalis
Which protozoan is a potential hazard to contact lens wearers?
Acanthamoeba
Name three species of trypanosomes, and where they are found in the world.
Trypanosoma brucei rhodesiense (E. Africa, very virulent)
Trypanosoma brucei gambiense (W. Africa)
Trypanosoma cruzi (Central, South America)
What is Winterbottom's sign?
Lymphadenopathy of the posterior cervical nodes that occurs in some patients infected with T. b. rhodesiense or T. v. gambiense.
Why are African typanosome infections called "African Sleeping Sickness"?
They invade the CNS and cause a lethargic, debilitating condition and can lead to coma and death. Victims appear sleepy/lethargic.
T.b rhodesiense invades CNS earlier than T. b. gambiense.
What is the reservoir host of African Sleeping Sickness?
Domestic animals and wild game.
What is the vector of African sleeping sickness?
Flies (genus Glossina, or tsetse flies). Bites from these flies are painful.
What is the vector of American trypanosomiasis?
Kissing bug- reduvid bugs.
Bite of these insects in painless hence the nickname "kissing bug".
What is another name for American trypanosomiasis?
Chaga's disease
T. cruzi is an intracellular parasite. What is its host tissue?
Heart tissue. It has been one of the leading causes of cardiomyopathy.
Describe the method of infection associated with kissing bugs.
The bug will bite painlessly often near the eyes or nose or mouth. When it ingests blood it also defecates. The saliva from the bite induces itching, and the victim rubs the feces into the wound while scratching to relieve the itch.
What is a Chagoma or Romana's sign?
Unilateral palpebral edema (one eyelid swells shut) the eye that received the bite of the kissing bug will become swollen after the bite. This is termed a Chagoma or Romana's sign.
Describe the pathology associated with long term Chaga's disease.
The parasites replicate in many different cell types to include CNS, muscle of hear, and bowel. The destruction of this muscle tissue results in loss of muscle tone and enlargement of the organ (heart, colon, esophagus).
True/False. Chaga's disease is a rare condition in Central and South America.
False. Prevalence rates are around 15 million persons in Central and South America. Simplest control is to use insecticides to eliminate the vectors.
Why don't we see large numbers of cases of Chaga's disease in the United States?
The United States does not have the required vector.
How is Chaga's disease diagnosed?
Simple method is Giemsa stained blood smears or examination of tissue sections for amastigotes. It is simple, but difficult and dependent on having large numbers of parasite present. ELISA methods and now PCR testing is available, but may be expensive or not readily available. Blood banks do NOT screen for the infection except by questionnaire. Can be transmitted by transfusion.
Leishmania present three clinical pictures, cutaneous, visceral, and muco-cutaneous. Each of these are associated with their own genus and species. Name the genus-species associated with each clinical presentation.
Leishmania tropica (cutaneous)
Leishmania braziliensis (mucocutaneous)
Leishmania donovani (visceral)
Name the vector for leishmaniasis.
Sandflies
What is a common name of cutaneous leishmaniasis found in Iraq?
Baghdad Boil
Which cells are parasitized by leishmania?
Cells of the reticulo-endothelial system, macrophages.
True/False. Leishmania infections are easily diagnosed with a simple blood smear.
False. Traditional diagnosis has been Giemsa stained tissue smears, and skin scrapings.
True/False. Cattle and sheep are the reservoir hosts of Leishmaniasis.
False. Dogs and rodents are important reservoir hosts of Leishmania.
What is the name of the flagellated stage of the leishmania parasite that is injected when the vector takes a blood meal?
The promastigote (mastix meaning whip...flagella in this case). This form is without flagella thus the name amastigote- without whip or flagella.
If a soldier presents with a skin lesion that is difficult to heal, and the soldier has a travel history that includes a recent deployment to Iraq, what parasitic disease might you add to your differential diagnosis?
Cutaneous leishmaniasis
What would be the specimen of choice for diagnosis of cutaneous leishmaniasis?
Skin scrapings.
This species of malaria is lethal and has developed drug resistance, making it more of a problem for man.
Plasmodium falciparum
This species of malaria parasitizes RBCs and makes them "sticky". The RBCs containing mature parasites adhere to the walls of capillaries and mature parasites are difficult to detect in a peripheral blood smear. Often only ring forms and gametocytes are present.
Plasmodium falciparum
This malarial parasite has a characteristic fever periodicity that produces a fever spike every 3 days (72 hours). This periodicity has led to a common clinical name. Name the genus and species as well as this clinical description of the fever cycle.
Plasmodium malariae, quartan malaria
Name the genus and species of the malaria that is sometimes described as benign tertian malaria.
Plasmodium vivax
Name the genus and species of malaria that is sometimes described as malignant tertian malaria.
Plasmodium falciparum
This species of malaria can infect liver cells and "hide" there, providing opportunities for a "relapse".
Plasmodium vivax
This species of malaria produces a sausage-shaped gametocyte that is diagnostic when seen in a blood smear.
Plasmodium falciparum
This form of the malarial parasite is ingested by the mosquito in a blood meal.
Gametocyte
This form of the parasite is injected by the mosquito while taking a blood meal.
Sporozoite
A definitive host is the host in which the sexual stage of reproduction takes place. What is the definitive host of malaria?
Mosquito
The intermediate host of a parasite is the host where the asexual stages of the parasites live. What is the intermediate host of malaria?
Humans
What type of reproduction do malaria parasites use to multiply in the liver?
Asexual reproduction (schizogony)- one cell divides to make two, etc. Progeny are called schizonts (from schizo) meaning split, these are "splitters".
How are soldiers protected against malaria?
Prophylactic doses of anti-malarial drugs can be given, use of insect repellent, mosquito netting while sleeping. Immunization is not effective.
What is the insect vector of malaria? What is the sex of the appropriate vector?
Mosquito, female
Malaria infected cells rupture and release the many progeny of the parasite- what is the name of the stage released from the red cell?
Merozoites
There are microgametocytes and macrogametocytes of malarial parasites. What is the difference in these two?
Macrogametocytes are analagous to the female
Microgametocytes are analagous to male.
The union of a microgamete and a macrogamete produces an ookinete.
Describe a typical patient presentation for a person infected with malaria.
Recent travel history (outside USA)
Complaint of high fever (maybe chills)
Headache
Myalgia
Arthralgia
Vomiting
Diarrhea
Splenomegaly
True/False. Never have to consider malaria in the USA since malaria is not endemic in the US.
False. Plasmodium vivax can infect liver cells and the patient might "relapse" upon return to the USA from an endemic area. Be watchful of anyone with a travel history to a malarious area, especially if they did NOT take prophylactic drugs.
Plasmodium falciparum is more dangerous than the other species of malaria. Why is that?
Plasmodium falciparum will infect all red cells, regardless of age, where other species are more selective. It is also sometimes drug resistant, and the infection can progress to death if not treated.
What is the normal definitive host for Toxoplasma gondii?
Cat
Toxoplasmosis is usually acquired by...?
Ingestion of oocysts from feces or poorly cooked flesh.
Congenital Toxoplasmosis infection is most like viral infection with...?
Rubella
Name the host of a sporozoan that causes congenital infections.
Cats
Cryptosporidium parvum is transmitted by...?
Fecal-oral route
Which protozoan "hides" in R-E cells and macrophages?
Leishmania spp.
Kala-azar (black fever in Hindu) is associated with which causative agent?
Leishmania donovani
Name a sporozoan that can cause congenital infections.
Toxoplasma gondii
Name the agent for muco-cutaneous leishmaniasis.
Leishmania braziliensis
Do you know another name for visceral leishmaniasis?
Kala-azar, black death
Name the vector for leishmaniasis.
Sandfly
Name the definitive host for malaria.
Mosquito
What is the vector for malaria?
Mosquito
Name the genus and species for quartan malaria.
Plasmodium malariae
Name the genus and species for benign tertian malaria.
Plasmodium vivax
Name the genus and species for malignant tertian malaria.
Plasmodium falciparum
Toxoplasmosis is especially harmful to what population group?
