Parasitic Central Nervous System Infections in Immunocompromised Hosts: Malaria, Microsporidiosis, Leishmaniasis, and African Trypanosomiasis

Abstract

Immunosuppression associated with HIV infection or following transplantation increases susceptibility to central nervous system (CNS) infections. Because of increasing international travel, parasites that were previously limited to tropical regions pose an increasing infectious threat to populations at risk for acquiring opportunistic infection, especially people with HIV infection or individuals who have received a solid organ or bone marrow transplant. Although long-term immunosuppression caused by medications such as prednisone likely also increases the risk for acquiring infection and for developing CNS manifestations, little published information is available to support this hypothesis. In an earlier article published in Clinical Infectious Diseases, we described the neurologic manifestations of some of the more common parasitic CNS infections. This review will discuss the presentation, diagnosis, and treatment of the following additional parasitic CNS infections: malaria, microsporidiosis, leishmaniasis, and African trypanosomiasis.As detailed in our previous article [1], the risk of acquiring fungal, viral, bacterial or parasitic infection is increased in patients receiving immunosuppressive therapy after transplantation and in people with advanced HIV infection. CNS infection occurs in 5%-10% of transplant recipients and up to 19% of patients with AIDS [2]. Patients with advanced HIV infection (CD4 + cell count, <200 cells/mm 3 ) and patients who require high levels of immunosuppression because of graft rejection or graft-versus-host disease are at greater risk than others of developing opportunistic CNS infections. Although parasitic CNS infection can occur in any host, some infections are more common among patients undergoing specific types of transplantation (table 1). The clinical and radiographic manifestations of parasitic CNS infection are often similar in immunocompromised and immunocompetent hosts, but certain infections may blunt or enhance these manifestations in immunosuppressed hosts [3,4]. Although neurologic symptoms vary somewhat by infecting parasite, they are mainly determined by the location(s) of the infection within the CNS (table 2).Evaluation of the immunosuppressed host presenting with neurologic symptoms or signs of infection should be guided by (1) the degree of immunosuppression, type of transplant received,

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