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118 CHAPTER 4

CASE STUDIES (CONTINUED)

6. A recent undocumented immigrant from Guyana, on the northeastern coast of South
America, visits the emergency room of a large hospital in the United States. He has
vague symptoms and the only sign of disease is that of several localized areas that are
inflamed and are manifested by pain and itching. Blood counts show a slight increase
in the level of the percentage of a white blood cell called an eosinophil. Through
an interpreter, the patient has experienced episodes of swelling in the extremities.
What is the most likely cause of these signs and symptoms? Is the infection likely to
occur in the United States?
7. A middle-aged Argentinian spent an extended vacation with relatives in the United
States. While visiting, he developed a series of painful ulcers on his mucous mem-
branes, particularly in the nose and mouth. He was taken to the family physician of
his relatives and upon physical examination was found to have significant lympha-
denopathy. Skin samples from the edges of some of the lesions revealed parasites
when stained with Giemsa stain and examined microscopically. What is the probable
name of this type of infection?

STUDY QUESTIONS

1. What do the terms intercellular and intracellular Gambian or chronic sleeping sickness, and T. brucei
mean? rhodesiense trypanosomes multiply in the blood and
are taken up by tsetse flies when they feed.
2. What are the symptoms of babeosis (sometimes are
extremely mild)? 10. Nematodes are threadlike, parasitic roundworms,
3. Why is the disease called leishmaniasis sometimes usually small, that infect tissue and blood of hu-
mans and other animals.
confused with malaria?
11. Lymphatic, subcutaneous, and body cavity
4. How is Leishmania transmitted?
infections.
5. What are the most common vectors of bacteria and
other organisms in the world? 12. Lymphatic filariasis is caused by infection with the
nematode worms Wuchereria bancrofti, Brugia
6. What are the four species of malaria that infect
malayi, and B. timori, all transmitted by mosqui-
humans?
toes. Microfilaria, particularly from W. bancrofti,
7. What kinds of organisms may be infected by the or- affect the circulation of the extremities, called el-
ganism causing toxoplasmosis? What is the primary ephantiasis, where the lymph system is impacted,
host for toxoplasmosis? causing swelling of the legs, particularly, and also
8. Oocysts are swallowed by a mouse, disseminated the scrotum.
infection follows with resistant stages forming in the 13. Onchocerciasis is the name for the condition, and
brain and the muscle; mouse is eaten by a cat and the Oncohocerca volvulus is the cause.
life cycle reverts to basic sexual pattern; humans also
14. Where was the parasite known as D. medinensis
eat meat infected with oocysts, contracting the disease.
initially seen?
9. In the Americas, T. cruzi is known to be spread
mainly by the reduviid bug, Hemiptera, in Africa,