An untreated AIDS patient $(CD4^4 count of 180 cells/mm^3)$ from southern California has developed a progressively severe headache and mental confusion, along with ataxia and retinochoroiditis. Focal lesions are present on a computed tomography scan of his brain. No mucocutaneous lesions are found. He has been living under a bridge for the past 2 years. His level of immunoglobulin G (IgG) to the infectious agent is high. What is the most likely explanation for how this current infection started?

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Quizplus · Accepted Answer

The most likely disease in this case is encephalitis with focal lesions. Because the patient has high levels of immunoglobulin G, the current infection is likely a reactivation of an earlier infection; therefore, recent exposures (choices D and E) can be eliminated. Exposure to pigeons suggests cryptococcosis, which is often a reactivational infection. However, in cryptococcosis antibody levels are rarely monitored, and there is no mention of India ink stain or capsular polysaccharide in the cerebrospinal fluid, which are the major diagnostic methods. In addition, based on the patient's symptoms, the infection is more likely to be encephalitis rather than meningitis or meningoencephalitis; also, retinochoroiditis is usually not present in cryptococcosis. The retinochoroiditis and lack of mucocutaneous lesions makes infection with Coccidioides less likely. Reactivation of toxoplasmosis is most likely.

An Untreated AIDS Patient (CD44countof180cells/mm3)(CD4^4 count of 180 cells/mm^3)(CD44countof180cells/mm3) From Southern California Has Developed a Progressively Severe Headache and Southern

An Untreated AIDS Patient $(CD4^4 count of 180 cells/mm^3)$ From Southern California Has Developed a Progressively Severe Headache and Southern