Page 274 - parasitology for medical and clinical laboratoryprofessionals

254 CHAPTER 12

INTRODUCTION (death). The infestation or infection (those inside the
body) of parasites is normally considered the domain
Skill must be exercised in determining the method for of lesser developed countries and regions of the world.
preparing specimens and identifying parasites that infect However, it has been estimated that in some rural areas
humans, which number into the hundreds. Professional of the United States, intestinal parasites may be found
knowledge and technical skills are both required to provide in large numbers. For instance, some rural medical clin-
the optimum care and diligence necessary to produce a ics with patients who primarily drink well water have
meaningful examination of a specimen for the presence reported extremely high intestinal parasite infections in
of parasites. today’s modern world with advanced medical practices
available in even the most remote locations.
Increasing numbers of people are traveling on a
INTRODUCTION TO DIRECT routine basis to endemic areas of the country and to other
AND INDIRECT IDENTIFICATION countries with regularity. Primary health care practi-
OF PARASITES tioners must become increasingly aware that parasites
not ordinarily found in a geographical area may be found
The first 11 chapters of this book are devoted to the during examination of patients and clinical specimens
history of the development of parasitology as it relates who are being treated for other medical conditions. Clin-
to human civilization and the life cycles and identifying ical laboratory technicians and technologists should
characteristics of most of the parasites that afflict hu- communicate with clinicians when patients have non-
mans. The medical impact of an infection by a parasite or specific clinical symptoms that may be due to parasite
parasites requires that the types of specimens necessary infections, and particularly for those patients who have
for optimizing the chances of recovery of the organisms traveled to other countries. There will no doubt need to
receive sufficient attention. Proper collection, transport be more awareness among both clinical personnel with
and storage of the specimen should precede the proce- patient care responsibility and for those who provide di-
dures for isolation and identification of the parasites, set- agnostic services such as radiography and labs. Education
ting the stage for accurate identification leading to proper and training components relative to the broad spectrum
treatment for the victim of an infection with a parasite or of both vectors and parasites should be stressed as the
parasites. The purpose of this summary of preliminary world shrinks and more medical challenges arise.
information is to provide a background to consider in
beginning the quest for recovery and identification of a
variety of parasites. IMMUNITY AND PREVENTION
As the student has learned from the previous OF PARASITIC INFECTIONS
chapters, the most important step is the recovery of and
identification of the organisms. Prevention is an impor- Many medical conditions that result in an impaired or
tant step, but in some areas of the world, it is virtually altered immune status may result in an infection of a
impossible to avoid or prevent parasitic infections. Only variety of parasites. In some cases, a human is an acci-
a small percentage of parasitosis cases are resolved with- dental host for a parasitic infection and may be entirely
out properly timed and handled specimens and careful unsuitable for the conditions necessary for a parasite to
examination of the samples by educated and trained maintain a population and to reproduce within a host. In
professional personnel. Chapter 12 includes the most these cases the human may be an accidental host but the
basic procedures in the files of parasitology, and when parasites are unable to reproduce and be transmitted to
used in conjunction with the previous chapters, the stu- others. But total lifetime immunity to parasitic infections,
dent should be successful in recovering, preparing, and unlike those for viruses and for some bacteria, is almost
identifying the bulk of parasites that impact the health never the case. In some countries or locales where large
of humans. numbers of the population are infested with a particu-
Worldwide, parasite infections are an important lar parasite, the victims may be asymptomatic, but this
component of human morbidity (illness) and mortality is not the same as being immune. This situation occurs