Chapter 9 Parasitic Disease Review Questions

Identify the three large groups of metazoal parasites.

-Roundworms -Tapeworms -Flukes

A small parasite that causes a skin rash:

Animal Schistosome

Large roundworm that lives in the intestinal tract of humans and that is acquired from ingestion of worm eggs.

Ascaris

Which parasite causes fever, cough, and pulmonary inflammation?

Ascaris Larvae

Which parasite causes itching of pubic skin?

Crab louse

Sexually transmitted parasite that causes an intense itching of the pubic skin.

Crab louse (Phthirus pubis)

Parasitic infestation is often considered to be insignificant in the US. Cite examples of protozoal parasitic disease that have caused significant public health problem in the US.

Cryptosporidiosis, caused by a parasite called Cryptosporidium parvum, which parasitizes the intestinal tract and can cause severe diarrhea. Cryptosporidosis became well-known when nearly half a million people in Milwaukee Wisconsin developed the disease in 1993. Many large outbreaks have occurred subsequent to this in the US. Toxoplasma gondii is a smaller intracellular parasite that infects a large number of birds and animals as well as humans. Many cats are infected with the parasite and excrete an infectious form of the organism in their stools. The importance of toxoplasmosis is related to its effect on the fetus. If a susceptible (nonimmune) woman acquires a toxoplasma infection during pregnancy, the parasite may be transmitted to the fetus. Infection of the fetus causes severe injury to fetal tissues and often leads to congenital malformations.

Which parasite causes Diarrhea from swimming in chlorinated swimming pool?

Cryptosporidium

Which parasite causes sever life-threatening diarrhea in an immunocompromised person?

Cryptosporidium

A small parasite that forms highly resistant cysts that may contaminate municipal water supplies, lakes and rivers, and swimming pools; ingestion of the cysts causes cramps and diarrhea:

Cryptosporidium parvum

An intestinal infection caused by a pathogenic amoeba:

Entamoeba histolytica

What is the source of most parasitic disease in the US?

From a public health point of view the source is either immigrants or travelers from areas of the world where such diseases are common. However, whipworm infection from contaminated soil or pinworm infections are still quite common-particularly the latter.

What parasitic diseases are acquired from unclean water sources?

Giradiasis, cryptosporidosis, amebiasis, and some flukes can all be acquired from unclean water.

An intestinal infection caused by a small pear-shaped parasite that causes intestinal cramps and diarrhea:

Girardia lamblia

An essential part of taking a patient's history is to question recent travel outside the US. Why is this information of particular relevance in cases of suspected parasitic disease?

Many parasitic diseases are most common in areas with poor public health, overcrowded living conditions, and lack of sanitation. Travel to such areas outside of the US (possible in US) may result in infection of travelers with parasitic diseases otherwise uncommon in the US.

Small (1 cm long) roundworm that inhabits the colon of infected children and periodically migrates out of the anus at night to deposit eggs on the perianal skin.

Pinworm

How do people become infected with pinworms? How do they acquire Ascaris infection?

Pinworm infection is usually the result of spread from person to person by the ingestion of eggs from contaminated bedding or other objects. Ascaris infection results from contact with fecally contaminated soil or by transfer of eggs from such soil onto food items.

Which parasite causes perianal itching awakening a child at night?

Pinworms

A protozoal disease transmitted by mosquitoes:

Plasmodium species

Fluke infestation that causes an itchy skin rash, as a result of swimming in a lake containing the infectious form of the parasite.

Schistosome

Which parasite causes swimmers itch?

Schistosomes

Which parasite causes chills and fever?

Species of the Plasmodium genus

Long ribbon-like worm that lives in the intestinal tract and that is acquired by eating the flesh of infected animals or fish.

Tapeworm

Several roundworms (nematode) parasites still frequently occur in the US, particularly in children. What are some simple precautions that can be taken to prevent infestation?

The infectious form of many nematode parasites is often found in the soil-having been shed in feces. Avoiding contact with soil (such as by not going barefoot and washing hands) will help to prevent infestation with man parasites.

How is malaria transmitted?

The parasite is transmitted to humans by the bite of the Anopheles mosquito. The initial source of the parasite is a blood meal taken by an anopheles mosquito, from an infected person.

What are some of the more important protozoal infections?

The protozoal infection malaria is likely the most important worldwide. Other include amebiasis, Chagas disease, Leishmaniasis, and several others.

What are the more important worm infestations? What are their manifestations?

The roundworm Ascaris and other intestinal roundworms such as the pinworm Enterobius, the whipworm Trichuris, the threadworm Strongyloides, a number of tapeworms and flukes are all of importance. With the exception of tapeworms (which often do not result in detectable disease) symptoms depend on the organ system parasitized. For example, Schistomsomes (flukes) may result in the deposition of eggs within the bladder and uterus. The extreme inflammation produced is a major risk factor for bladder cancer in some Asiatic countries.

Parasite that infests many birds and animals and that can be transmitted to humans by ingestion of incompletely cooked meat (such as hamburgers) or by contact with infected cats that excrete an infectious form of the parasite in their feces.

Toxoplasma

Which parasite causes injury to the fetus of a pregnant woman?

Toxoplasma

A parasitic infection that may be acquired by contact with cats:

Toxoplasma gondii

A parasitic infection that may be transmitted from a recently infected pregnant woman to her fetus:

Toxoplasma gondii

Small roundworm that forms cysts in the muscles of infected animals and may cause a serious systemic illness in persons who ingest the cysts contained in incompletely cooked meat.

Trichinella

What is trichinosis? How is it transmitted?

Trichinosis (now trichinellosis) is caused by parasitization with a small roundworm Trichinella spiralis. Although people formerly become infected by eating improperly cooked pork, now the source is undercooked wild game. Initial symptoms (within days of ingestion) relate to gastrointestinal distress. With time muscle pain and, less commonly, heart problems may occur as a result of invasion of muscle tissue.

Which parasite causes profuse vaginal discharge?

Trichomonas

A sexually transmitted infection caused by a small motile parasite that does not form cysts:

Trichomonas vaginalis