Parasitic and Fungal Disorders and Neurosarcoidosis

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50 Parasitic and Fungal Disorders and Neurosarcoidosis

Parasitic infections of the nervous system range from acute syndromes such as diffuse cerebritis in cerebral malaria to more chronic mass lesions causing seizure disorders such as neurocysticercosis. This chapter will focus on the most common parasites causing central nervous system infections.

Cerebral Malaria

Clinical Vignette

A 45-year-old previously healthy, Indian male, working as an engineer in the United States returned from India in August after a 6-week stay visiting with his parents. One week after his return, he presented to the emergency ward with 4 days of fever to 102° F, headache, and diarrhea. His facies was flushed; he had mild confusion, severe lethargy, a moderately stiff neck, and a temperature of 39.4° C (103° F). A lumbar puncture demonstrated a normal cerebrospinal fluid (CSF). His peripheral WBC was 12,000/mm3, with a hemoglobin of 10 g and a platelet count of 40,000/mm3. His blood glucose level was 56 mg/dL. A peripheral blood smear demonstrated multiple intraerythrocytic ring forms consistent with the trophozoites of Plasmodium falciparum with a parasite count of 3%.

The patient was treated with intravenous artesunate, obtained from the Centers for Disease Control and Prevention (CDC), and doxycycline. He became afebrile, alert, and oriented after 3 days of intravenous therapy. His oral treatment regimen was completed after 7 days of doxycycline.

Comment: Malaria remains a major cause of morbidity and mortality in the developing world and the most important treatable cause of acute parasitic infection in travelers returning to their Westernized homelands. In the United States, 1564 imported cases were reported during 2006; 39% were attributable to P. falciparum. Immigrants who have recently visited with friends and relatives in their countries of origin often do not take antimalarial prophylaxis and are at higher risk of acquiring malaria.

Malaria continues to have a global presence, primarily affecting individuals living in South and Central America, Africa, and Asia (Fig. 50-1). Close to a half billion individuals are affected annually with up to a million deaths each year. Previously endemic in the United States, public health measures have greatly decreased its incidence here. However, at least a thousand cases are reported annually here and are primarily related to P. falciparum affecting travelers to endemic geographic areas.

Therapy

Increased drug resistance has led to combination therapy for malaria. The treatment of cerebral malaria consists of either intravenous quinidine or artesunate accompanied by doxycycline (Fig. 50-2). Intravenous quinidine has to be administered in an ICU setting with electrocardiographic monitoring, as it may lead to severe arrhythmias. Exchange transfusion should be strongly considered for persons with a parasite density of more than 5–10% or even with a lower level of parasitemia if the cerebral malaria is severe or other complications of the malaria occur, including non–volume overload pulmonary edema, or renal complications.

African Trypanosomiasis (Sleeping Sickness)

Clinical Vignette

A 38-year-old West African woman, who migrated from her native country 4 months ago, was evaluated in an emergency department for a few weeks of bizarre behavior. In the preceding months, she noted modest weight loss and progressive failure to thrive. She was referred to an inpatient psychiatric service, where she became more lethargic. Her physical examination revealed a low-grade fever with a suspicion of hepatomegaly but was otherwise normal.

Laboratory tests demonstrated a white cell count of 6400/mm, hemoglobin 10 g, and normal platelets. Her liver function tests revealed a mild transaminitis. A careful exam of her peripheral blood smear showed a trypomastigote. HIV antibody was negative. The patient’s basic CSF parameters were normal. However, both her indirect fluorescent antibody (IFA) and enzyme-linked immunosorbent assay (ELISA) to Trypanosoma gambiense in her CSF were positive. Treatment was started with melarsoprol but was stopped because of progressive encephalopathy. The patient’s family signed her out of the hospital against medical advice and she was lost to follow-up.

Comment: With the world becoming “smaller,” previously “exotic” infectious diseases may now be seen anywhere, including economically highly developed countries. Cultural issues also arise, as well illustrated here, where the family made a decision not to allow attempts at a second line of therapy such as intravenous eflornithine when the first medication trial was not successful.