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  1. What is meant by a parasitic infection?

  2. Why are parasitic infections increasing in incidence in the United States and Europe?

  3. What patient population is particularly at risk of severe and life-threatening parasitic infections?

  4. What does the infectious disease specialist mean by parasitic infection?

Most infectious agents fulfill the definition of a parasite: an organism that grows, feeds, and shelters on or in a different organism and contributes nothing to the host. However, medical science has created the classification “parasite” to include a complex group of nonfungal eukaryotic human pathogens. Unlike fungi, parasites have no cell wall and are often motile. In addition, many parasites require two or more host species to complete their life cycle, and they reproduce both sexually and asexually. The host in which sexual reproduction takes place is called the “definitive host,” and the one in which asexual reproduction occurs is called the “intermediate host.”

Parasitic infections remain a major health problem in developing countries with poor sanitation. It is mandatory that caregivers practicing in these countries have a working knowledge of human parasites. With the marked rise in international travel and increased military deployments to endemic areas, these infections are now also increasingly being diagnosed in the United States, Europe, and other developed countries. The incidence of symptomatic parasitic infections has also increased because of the ever-increasing population of immunocompromised hosts. Organ transplant, cancer chemotherapy, and infection with HIV all lead to depressed cell-mediated and humoral immunity, allowing dormant parasites to reactivate and cause disease. Therefore, caregivers everywhere must be familiar with these diseases. More than ever before, thorough travel and exposure histories are critical steps in accurately diagnosing parasitic infections. An awareness of geography and environmental conditions and a familiarity with the life cycles of various parasites are all required for proper diagnosis and treatment.



Hours can make the difference between life and death. Rapid diagnosis and treatment are critical.



  1. Which form of malaria is the most dangerous, and why?

  2. Which disease does malaria most commonly mimic?

  3. How is malaria diagnosed? Is there a particular time in the course of illness when diagnostic studies should be performed?

  4. Why are many African Americans more resistant to some forms of malaria?

  5. What are the current recommendations for malaria treatment, and what are the factors that dictate the regimen of choice?

  6. When should chemoprophylaxis be started, and how long after completion of a trip to an endemic area should preventive therapy be continued?


The combination of deteriorating political and economic conditions in the countries of sub-Saharan Africa and the development of chloroquine drug resistance in many parts of the world have limited progress in controlling malaria. Climate change and the increased resistance of mosquitoes to insecticides have also slowed ...

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