Page 38 - parasitology for medical and clinical laboratoryprofessionals

18 CHAPTER 2

may be determined. Easily transportable field laboratories categorization by the WHO. Blood loss in heavy infec-
are now available for working in remote locations, where tions and malnutrition associated with heavy infections of-
organisms may be identified microscopically and then pre- ten prompt treatment by a number of health organizations
served for further study. Medical treatment teams from the that operate throughout the world. Parasitic infections of a
military services, private charitable organizations, and other widespread nature tend to rob the population of vital en-
governmental agencies often accompany the surveillance ergy and the will to progress toward a better lifestyle.
teams to provide treatment for residents of the area.
Most areas of the world contain both rural and
metropolitan regions that are available for definitive stud- SIGNS AND SYMPTOMS OF
ies related to outbreaks. This information is important ac- PARASITIC INFECTIONS
ademically as well as for scientific study by agencies such
as the WHO, divisions of the United Nations, and even Signs (what you can see) and symptoms (what the patient
U.S. agencies such as the CDC. Certain climactic condi- feels) are many and varied and are dependent upon the
tions as well as living conditions contribute to creating an type of parasite or parasites with which the victim is in-
environment for transmission of parasites. Rural dwellers fected. People with intestinal parasite infections are usu-
who drink ground water from shallow wells that may have ally undernourished and weak, and may be concurrently
runoff from agricultural sites and animal grazing in the infected with viruses, fungi, or bacteria. The malnour-
area contribute heavily to the transmission of many para- ished state may also lead to certain types of chemical and
sites. A lifestyle involving contamination of food and wa- metal poisoning due to toxins excreted by the organisms.
ter sources, coupled with the lack of availability of health There is no difference in age or gender of those who ex-
care and sanitation devices and services, are involved in perience parasitism, as human intestinal parasites can be
the majority of clusters of parasitic infection. present with any disease, in any person, and at any age.
In order to perform a study in a geographic location, Parasitic infections may show a broad and confusing ar-
it is necessary to obtain permission from the government ray of symptoms, many of which are related to the gastro-
agencies and sometimes on a local level, where the indig- intestinal tract. The most commonly reported complaints
enous population may be suspicious of strangers in their are periods of diarrhea, alternating with periods of con-
midst making observations. Meetings are necessary with stipation. This may be accompanied by bloating and
community members to explain the purpose and manner possibly edema, nausea, loss of appetite, and other signs
in which the study will be conducted. Participation is of an irritated bowel (Figure 2-3). Other symptoms not
voluntary, and participants must be allowed to withdraw related to the intestinal tract may include night sweats,
from the study at any time. Most helminth infections may low tolerance to exercise, intermittent low-grade fevers,
be diagnosed by grossly observing the organism on stool recurrent sore throats, low energy, more “allergic”-type
(fecal) specimens, or by finding the eggs (ova) of the or- reactions, and possibly behavioral changes.
ganisms by performing certain sedimentary procedures, General symptoms and signs will be covered in the
with the use of ethyl acetate, which has largely replaced sections of this book dealing specifically with the iden-
the ether and formalin method, to assess the specimens tification of particular organisms. Symptoms of some of
for eggs. Some specimens must be examined as soon as the various remaining parasites not described previously
possible, as some features of the eggs may be difficult or may generally cause such clinical signs as anemia, irrita-
impossible to visualize after being passed as much as an tion of the gastrointestinal mucosa, and blockage of the
hour earlier. organs as common complaints. Cysts that are embedded
Although parasitic infections do not progress to the in tissues of the body and that resemble cancer may also
proportions by which viral and bacterial infections leading occur with some of these virulent organisms (Figure 2-4).
to epidemics and pandemics are characterized, they are, Dehydration from severe diarrhea or anemia related to
nonetheless, of vital importance. The infestations or infec- parasitic infections also provides important diagnostic
tions are usually limited to small groups and are dependent information to health care teams.
upon the presence of proper conditions for survival and Spirochetes are very tiny bacteria and are spiral-
passing of the parasites. The morbidity of the infestations shaped as a group and include both aerobic and an-
and the mortality as well as the number of worms present aerobic species. Spirochetes exist as both free-living
in the host (intensity level of infestation) is required for and parasitic forms, where they multiply in the blood