1.3. STAT TESTING IN PARASITOLOGY

STAT REFERS TO COLLECTION, PROCESSING, TESTING, AND REPORTING

REQUEST FOR BLOOD FILM EXAMINATION

Although malaria is no longer endemic within the United States, it is considered to be life-threatening, and laboratory requests for blood smear examination and organism identification should be treated as "STAT" requests. Patients with malaria may appear for diagnostic blood work when least expected. Laboratory personnel should be aware of the "STAT" nature of such requests and the importance of obtaining some specific patient history information. The typical textbook presentation of the blood smears may not be seen by the technologist. It becomes very important that the smears be examined at length and under oil immersion. The most important thing to remember is that even though a low parasitemia may be present on the blood smears, the patient may still be faced with a serious, life-threatening disease. Many travelers who present to the emergency room are considered “immunologically naïve” and have never been exposed to malaria before; therefore they may be symptomatic with a VERY LOW PARASITEMIA. Request for ALL POTENTIAL BLOOD PARASITES SHOULD BE HANDLED AS STATS.

REQUEST FOR EXAMINATION OF SPECIMENS FOR FREE-LIVING AMEBAE

Amebic meningoencephalitis caused by N. fowleri is an acute, suppurative infection of the brain and meninges. With extremely rare exceptions, the disease is rapidly fatal in humans. The period between contact with the organism and onset of clinical symptoms such as fever, headache, and rhinitis may vary from 2 to 3 days to as long as 7 to 15 days. Primary amebic meningoencephalitis (PAM) can resemble acute purulent bacterial meningitis, and these conditions may be difficult to differentiate, particularly in the early stages. The CSF may have a predominantly polymorphonuclear leukocytosis, increased protein, and decreased glucose concentration like that seen with bacterial meningitis. Unfortunately, if the CSF Gram stain is interpreted incorrectly (identification of bacteria as a false positive), the resulting antibacterial therapy has no impact on the amebae and the patient will usually die within several days.

Clinical and laboratory data usually cannot be used to differentiate pyogenic meningitis from PAM, so the diagnosis may have to be reached by a process of elimination. A high index of suspicion is often mandatory for early diagnosis. Although most cases are associated with exposure to contaminated water through swimming or bathing, this is not always the case. The rapidly fatal course of 3 to 6 days after the beginning of symptoms (with an incubation period of 1 day to 2 weeks) requires early diagnosis and immediate chemotherapy if the patient is to survive.

Requests for examination of specimens for the other free-living amebae (Acanthamoeba, Sappinia, Balamuthia) should also be considered STAT requests.