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9 - PARASITOLOGY
- from PART II - LESS COMMON INFECTIONS
- Edited by John C. Hall, University of Missouri, Kansas City
- Brian J. Hall
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- Book:
- Skin Infections
- Published online:
- 08 January 2010
- Print publication:
- 06 April 2009, pp 117-132
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- Chapter
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Summary
This chapter will cover most of the organisms that directly or indirectly compromise tissues through human infection. Although in developed countries they are considered exotic diseases just to be diagnosed in travelers, many of them represent a major health problem for developing countries around the world.
HISTORY
Parasites have accompanied mankind since antiquity. Dracunculiasis is described in the Ebers papyrus from 1500 BC, and references to this disease are clearly identified in the Bible. The ancient symbol of medicine, the staff of Asklepios, is believed by some scholars to also represent the treatment of dracunculaisis which involves slowly extracting the worm by winding it around a stick. This treatment is still in use to this day. Tenias were described by the ancient Greeks and are cited by Aristotle in his History of Animals.
Protozoa have ancient history in human disease annals. Evidence of Trypanosoma cruzi DNA has been found in mummies from Peru and northern Chile dating from 2000 BC to AD 1400. Old world cutaneous leishmaniasis is described on tablets in the library of King Ashurbanipal from the 7th century BC. The famous Arab physician Avicenna already described oriental sore in the 10th century as Balkh sore. New world leishmaniasis, as mucocutaneous disease, is clearly represented in ancient Peruvian pottery from the 5th century. The separation of Old World and New World Leishmanisis was a contribution of Gaspar Vianna, who in 1911 created a new species, Leishmania braziliensis.
TECHNIQUES IN DIAGNOSING DERMATOLOGIC MANIFESTATIONS OF INFECTIOUS DISEASES
- Edited by John C. Hall, University of Missouri, Kansas City
- Brian J. Hall
-
- Book:
- Skin Infections
- Published online:
- 08 January 2010
- Print publication:
- 06 April 2009, pp 2-7
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- Chapter
- Export citation
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Summary
GETTING THE SAMPLE
A vital step toward making the right diagnosis when dealing with infectious diseases is ordering the appropriate test. That implies having a certain idea of the range of possible organisms involved and directing your workup toward ruling in or out a specific agent. Of course, there will be cases where a more blind approach is in order and a large range of diagnostic possibilities should be considered. In those situations, smears and cultures for bacterial, mycobacterial, and fungal microorganisms are indicated. Also viral diseases should be considered in specific situations, such as febrile patients with disseminated maculopapular or vesicular rashes. However, just for practical purposes, it is better to take a syndromic approach, considering a range of possibilities regarding the etiology of the lesions and then, selecting the appropriate test. Let us take an example such as a patient with a sporotrichoid pattern of lesions. If the diagnosis to confirm is sporotrichosis, a fungal culture will be very sensitive and very specific. Pyogenic bacteria such as Staphylococcal aureus can also produce such a pattern. In these cases, a Gram stain and routine culture will be helpful. But, if the patient likes fishing, swimming, or diving besides gardening an atypical mycobacterial infection (M. marinum) also has to be listed in the differential. In such cases, a biopsy, acid-fast stain, and mycobacterial culture should also be considered, although recognizing this is a difficult diagnosis to make because of the low sensitivity of each individual test.