Page 164 - The Vasculitides Volumes 2

140 Patricia K. Coyle

Mucormycosis
Mucormycosis is due to infection by filamentous fungi of the order Mucorales and class

Zygomycetes. They are ubiquitous organisms in bread mold, soil, manure, and decaying
vegetation, and the second commonest invasive mold infection [83, 84]. Rhizopus, Mucer,
and Lichtheimia are the most common genera to cause mucormycosis. Immunocompromised
hosts are at particular risk. Underlying conditions include diabetes mellitus, hematologic
malignancy, trauma, solid cancers, and solid organ transplants.

Sites of infection include lung, skin, gastrointestinal tract, and the rhino-orbito-cerebral
region. Iron is an important component in this infection. These fungi contain spore coat
homolog proteins that are unique, and required for angioinvasion [85]. The result of this
blood vessel invasion is vessel thrombosis and tissue necrosis. The rhino-orbito-cerebral form
may produce suggestive necrotic nasal or sinus eschars. Patients may experience carotid or
basilar artery thrombosis, cavernous sinus thrombosis, or intracerebral hemorrhage [86, 87].

Diagnosis is based on clinical suspicion confirmed by biopsy, scraping, or culture. PCR is
being evaluated. Treatment involves a combination of surgery and systemic therapy [88].
Liposomal amphotericin B is favored therapy however thiazoles and posaconazole antibiotics
have been used in selected individuals.

Parasitic Pathogens

Taenia Solium

Cysticercosis due to infection with the larval stage of the pork cestode tapeworm Taenia
solium is the commonest CNS parasite accounting for 10% of stroke cases in endemic areas
[89], and a major cause of headache and seizures. Lenticular striate lacunar infarcts are more
common than large artery stroke, however TIA and intracranial hemorrhages also occur [4,
90]. Among 28 patients with subarachnoid cysticercosis [91], 15 (53%) had angiographic
evidence of cerebral arteritis, 12 (80%) of whom had a stroke syndrome (P=0.02). Eight of
the 15 patients (53%) with cerebral arteritis had evidence of cerebral infarction on MRI,
whereas only one patient without cerebral arteritis had cerebral infarction (P=0.05). The most
commonly involved vessels were the MCA and posterior cerebral artery (PCA). Small vessels
are preferentially affected, with superficial cortical vessel thrombosis, occlusive endarteritis,
and focal arteritis. Larger circle of Willis vessels are involved when severe arachnoiditis is
present. Diagnosis involves antibody testing and suggestive findings on neuroimaging;
however antigen testing is not routinely used. Anti-helminthic therapies include the
benzimidazole drug albendazole and the anti-helminthic drug praziquante with
corticosteroids.

Plasmodium Falciparum

Plasmodium falciparum is a unicellular parasitic protozoan that infects humans causing
more severe forms of malaria. The disease is typically transmitted by the bite of an infected
female Anopheles mosquito. Inoculated sporozoites infect and multiply in liver cells, then

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