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LEARNING OBJECTIVES

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LEARNING OBJECTIVES

Upon completion of the chapter, the reader will be able to:

  1. Identify the primary reasons why some parasitic diseases may be more prevalent in the US population.

  2. Describe the treatment algorithm for giardiasis and amebiasis.

  3. List one effective therapy for nematodes and select the drugs of choice for strongyloidiasis and tapeworms.

  4. List three major reasons why travelers are infected with malaria.

  5. Describe the presenting signs and symptoms of malaria.

  6. List some specific toxicities of mefloquine.

  7. Identify the monitoring parameters for quinidine gluconate in severe malaria.

  8. Define the major complications of falciparum malaria.

  9. Discuss the cardiovascular complications of chronic South American trypanosomiasis.

  10. Describe the steps to take to eradicate lice infestation and scabies.

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INTRODUCTION

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The increased desire of large segments of the US population to travel to Asia, Africa, and other parts of the world can expose them to parasitic infections that are endemic in those areas. The influx of refugees and new immigrant populations from Asia and other parts of the world have brought new parasitic infections to our shores. Migrant farm workers, the large and growing Central and South American immigrant population, and the presence of immunosuppressed populations (eg, those with the AIDS and transplant patients) represent significant sources of parasitic infections in the United States.1,2,3,4,5

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Terms that are frequently used when discussing parasitic diseases are as follows.6 Symbiosis means “living together,” when two species are dependent on each other for food and protection. The term commensalism, implies a mutual association in which both organisms may benefit, or at least one benefits but does no harm to the other. In contrast, parasitism, although resembling symbiosis in that it is also an intimate relationship between two species does not represent a mutually beneficial association. One species (the host) does not benefit from the relationship, and in fact the relationship may be detrimental to its survival.

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Parasites have made metabolic and other defensive adaptations over time to increase their ability to survive host defenses and have allowed them to utilize the host’s biochemical systems to synthesize necessary cellular components. Beef and pork tapeworms (cestodes) possess highly developed reproductive systems that allow them to transfer easily to new hosts. Because of the lack of digestive systems, cestodes are completely host-dependent for all nutrients. Cestodes (tapeworms) (Taenia saginata and Taenia solium) use specialized suckers that enable them to obtain blood and vital nutrients from their host. Entamoeba histolytica, once it has gained access to the human colon or large intestine is able to invade and utilize its specialized proteolytic enzyme to erode the GI mucosa. E. histolytica is also able to survive in adverse conditions by walling itself off and forming cysts; this protects the parasite from environmental conditions until it is ready to infect the next host.

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Although acquired immunity ...

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