Page 305 - parasitology for medical and clinical laboratoryprofessionals

Laboratory Procedures for Identifying Parasitic Organisms and Their Ova 285

SUMMARY

A number of parasites from human blood must be identifying the causative organisms for the blood and
stained with certain stains in order to identify the caus- tissue parasites.
ative organisms for the blood-borne parasites. Human No current technology comes close to recovering
blood parasites, such as Plasmodium, which causes and identifying the numbers of parasitic infections that
malaria; trypanosomes that cause African sleeping are actually in existence. A dedicated staff that insists on
sickness; and American trypanosomiasis (Chagas’s scrupulously performing the tasks for identifying defini-
disease), as well as babesiosis, comprise most of these. tively the causative organisms for parasitic infections is
Safety practices for those performing the tests, and the best tool for accuracy and efficiency. Antibody stud-
scrupulous attention to detail are required to correctly ies that are available do not distinguish between current
identify these pathogens. Smear findings should only infections or past infections, and the manner of collection
be released by competent technical personnel able to of samples, with the cooperation of the patient, is still not
review, interpret, and evaluate sometimes nebulous completely satisfactory, and many cases of infection are
results. The timing of blood and tissue collection, missed. No doubt newer detection methods, rather than
the manner in which the specimens are prepared and those labor-intensive procedures currently used, will re-
stained, must be followed carefully in order to en- place these methods, and more accurate determinations
hance the chances of successfully finding and correctly of infection may come to reality.

STUDY QUESTIONS

1. What are some methods used for diagnosing para- 9. List the three helminthes.
sitic infections?
10. Compare cysts and trophozoites of intestinal
2. Name three major groups of human parasites. protozoa.
3. In what ways does climate and region affect the 11. What dilutant is most often used for wet mounts?
types of parasites there? 12. Relate the two concentration methods for fecal
4. Name three body sites where parasites may be found. specimens.
5. What are three ways parasites may be transmitted? 13. Why is it necessary to employ Standard Precautions
6. What are the procedures for diagnosing blood and when handling parasite specimens?
tissue parasites? 14. Why is it necessary to calibrate the ocular of the
7. What are the four species of Plasmodium that microscope with a stage micrometer?
humans may contract? 15. Why are thick and thin preparations required for
8. Name the families for tapeworms and roundworms. blood parasites?

REFERENCES

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Application of the polymerase chain reaction to the Diversity Web. Accessed January 20, 2009 at http://
epidemiology of pathogenic and nonpathogenic Enta- animaldiversity.ummz.umich.edu/site/accounts/
moeba histolytica. Am. J. Trop. Med. Hyg. 48:58–70. information/Brugia_malayi.html.
Ali, I. K. M., M. B. Hossain, S. Roy, P. F. Ayeh-Kumi, W. A. Avicenna (Ibn Sina). C1000. Al Canon fi al Tib. See Libri
Petri, Jr., R. Haque, and C. G. Clark. 2003. Entamoeba in re medica omnes qui hactenus ad nos pervenere,
moshkovskii infections in children, Bangladesh. Emerg. p. 1–966, Venetiis.
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