diseases, particularly parasitic infections, play a huge role in the overall world’s health and economy. As travel increases, we anticipate seeing many more people who will be infected with parasites that may not be endemic to the specific area where they live. Continued vector and disease control efforts will remain on the high-priority list, especially when seen within the context of global health. Hopefully, parasitologists, including those who have diagnostic skills, will be available to support these global initiatives.
Acknowledgments
I thank the hundreds of colleagues over the past years who have shared their thoughts and suggestions regarding this fascinating field of diagnostic parasitology. There are too many of you to name—you all know who you are and we all recognize the pitfalls, as well as the fun, in providing diagnostic services in this field of microbiology.
I also thank the many bench techs and microbiologists who have tackled this field over the last 30+ years, including those who attended workshops and seminars; your contributions to the growth and expansion of diagnostic parasitology have been significant. Discussions of questions asked, problems for resolution, and reviews of testing options have been invaluable in shaping our approach to diagnostics in this field. This type of interaction, including the many discussions with the UCLA microbiology staff in the parasitology area, helped all of us keep an open mind when reviewing options and possible new ways to approach the work.
Over the years, our association with many companies has also been extremely valuable in helping understand test development, test trials, and relevance of results to the ultimate user within the diagnostic laboratory. Again, these interactions have helped maintain some balance and perspective on new options and their relevance to improved patient care.
A challenge to all of us who are still actively working in this area of diagnostic microbiology: serve as a mentor to some of the young people entering the field of microbiology. The number of personnel trained in this field continues to decline. Until parasite morphology is no longer required for differentiation and diagnosis, skilled microscopists will remain valuable members of the microbiology team and mandatory for the practice of diagnostic medical parasitology.
I thank Sharon Belkin for the new illustrations; she is always capable of translating my verbal descriptions into clear and accurate depictions of the various organisms. This is a true art, and she brings considerable expertise to the process; pictures are always a tremendous addition to verbal descriptions.
I also thank members of the editorial staff of ASM Press, including Susan Birch, Jeff Holtmeier, and our copy editor, Yvonne Strong; they are outstanding professionals. Susan’s expertise always helps the authors “look good,” and I appreciate her collaboration not only as an editor but also as a friend and colleague.
Above all, my very special thanks go to my husband, John, for his love and support for this and other projects over the years. I could never have taken on these challenges without his help, understanding, and wonderful sense of humor.
SECTION 1 Philosophy and Approach to Diagnostic Parasitology
Why Perform This Type of Testing?
Travel
With the increase in world travel and access to varied populations and geographic areas, we continue to see more “tropical” diseases and infections outside areas of endemicity due to the rapidity with which people and organisms can be transmitted from one place to another. Travel has also become accessible and more affordable for many people throughout the world, including those whose overall health status is in some way compromised. The increased transportation of infectious agents and potential human carriers, particularly via air travel, has been clearly demonstrated during the last few years. It has also been well documented that vectors carrying parasitic organisms can be transported via air travel in baggage and in the unpressurized parts of the plane itself; once released, these infected vectors can then transmit these parasites to humans, even in areas where the infections are not endemic.
Population Movements
In many parts of the world, particularly where conflict is ongoing, there continue to be large population movements. Many of these individuals become a part of refugee migrations to and from areas of endemic parasitic diseases. Often in refugee situations, living conditions are very poor and medical limitations may lead to high levels of parasitic disease and severe illness. Also, migrants may move into countries and geographic areas where serious parasitic infections are generally nonendemic, including Europe and parts of North America. Even if these individuals are uninfected when entering these areas, travel home to visit relatives may result in infections that can be imported when they return.
Control Issues
Control of parasites that cause disease is linked to a number of factors including geographic location, public health infrastructure, political stability, available funding, social and behavioral customs and beliefs, trained laboratory personnel, health care support teams, environmental constraints, degree of understanding of organism life cycles, and opportunities for control and overall commitment. Often control efforts do not cross political or geographic boundaries; unfortunately, vectors and other carriers of infectious agents do not play “by the rules”; as a result, these boundaries become meaningless.
Global Warming
With continued increase in the global temperature, worldwide climate changes are leading to an overall increase in infectious diseases, vector populations, and endemic ranges of both parasites and vectors. Global warming enhances the potential spread of tropical parasitic infections, specifically those due to parasites such as Plasmodium spp., Leishmania spp., and Trypanosoma spp. Examples of vectors whose range is increasing include Anopheles, Aedes, and Culex mosquitoes, hard ticks, and triatomid bugs.
Epidemiologic Considerations
When newer infectious agents and/or diseases are recognized, there is often very little information available regarding the organism life cycle, potential reservoir hosts, and environmental requirements for survival. Priorities may change, and epidemiologic considerations may have been moved lower on the priority list in areas of the world where they were considered important in the past; unfortunately, funding often plays a role in decisions that impact disease control measures.
Compromised Patients
With the tremendous increase in the number of patients whose immune systems are compromised through underlying illness, chemotherapy, transplantation, AIDS, or age, we are much more likely to see increasing numbers of opportunistic infections, including those caused by parasites. Also, we continue to discover and document organisms that were thought to be nonpathogenic but, when found in the compromised host, can cause serious disease. In assessing the possible cause of illness in this patient population, the possibility of parasitic infections must be considered as part of the differential diagnosis.
Approach to Therapy
As
