Toxoplasmosis in HIV/AIDS Patients - A Living Legacy

The coccidian Toxoplasma gondii (T. gondii) is a ubiquitous, intracellular, protozoan parasite that causes toxoplasmosis, a cosmopolitan zoonotic disease. Toxoplasma infections are reported in approximately half of the world’s population but most are asymptomatic. T. gondii may serve as one factor that can enhance the immunodeficiency found after HIV-1 infections. Co-infection with other pathogens in humans infected with HIV-1 may enhance the progression of the disease to AIDS (Lin & Bowman, 1992). In concurrence with HIV infection, cerebral toxoplasmosis (CT) occurs primarily due to reactivation of latent Toxoplasma infection and is one of the most frequent opportunistic infections, particularly in patients with full-blown AIDS. CT is the most common clinical presentation of toxoplasmosis (Luft & Remington, 1992), and is one of the most frequent causes of focal intracerebral lesions that complicates AIDS (Nissapatorn et al, 2004). CT is undoubtedly a serious life-threatening disease but it is treatable when there is a timely diagnosis and prompt treatment, and there are no other concurrent co-infections. When HIV-infected patients develop CT this poses many diagnostic and therapeutic challenges for clinicians (Israelski & Remington, 1992), particularly in developing countries where the infrastructure is limited but the number of patients infected with HIV is increasing. This chapter focuses on the clinico-epidemiological aspects of toxoplasmosis in HIV/AIDS patients at the time of transition to treatment with highly active anti-retroviral therapy (HAART). The course of toxoplasmosis in HIV/AIDS patients should be able to provide us with a better understanding of the clinical scenario and future management of this so-called “enigmatic parasite” of the tropics.