26.4 Fungal and parasitic diseases of the nervous system  (Page 3/15)

Granulomatous amoebic encephalitis

Acanthamoeba and Balamuthia species are free-living amoebae found in many bodies of fresh water. Human infections by these amoebae are rare. However, they can cause amoebic keratitis in contact lens wearers (see Protozoan and Helminthic Infections of the Eyes ), disseminated infections in immunocompromised patients, and granulomatous amoebic encephalitis (GAE) in severe cases. Compared to PAM, GAE tend to be subacute infections. The microbe is thought to enter through either the nasal sinuses or breaks in the skin. It is disseminated hematogenously and can invade the CNS. There, the infections lead to inflammation, formation of lesions, and development of typical neurological symptoms of encephalitis ( [link] ). GAE is nearly always fatal.

GAE is often not diagnosed until late in the infection. Lesions caused by the infection can be detected using CT or MRI. The live amoebae can be directly detected in CSF or tissue biopsies. Serological tests are available but generally are not necessary to make a correct diagnosis, since the presence of the organism in CSF is definitive. Some antifungal drugs, like fluconazole , have been used to treat acanthamoebal infections. In addition, a combination of miltefosine and voriconazole (an inhibitor of ergosterol biosynthesis) has recently been used to successfully treat GAE. Even with treatment, however, the mortality rate for patients with these infections is high.

Human african trypanosomiasis

Human African trypanosomiasis (also known as African sleeping sickness ) is a serious disease endemic to two distinct regions in sub-Saharan Africa. It is caused by the insect-borne hemoflagellate Trypanosoma brucei . The subspecies Trypanosoma brucei rhodesiense causes East African trypanosomiasis (EAT), and another subspecies, Trypanosoma brucei gambiense causes West African trypanosomiasis (WAT). A few hundred cases of EAT are currently reported each year. US Centers for Disease Control and Prevention, “Parasites – African Trypanosomiasis (also known as Sleeping Sickness), East African Trypanosomiasis FAQs,” 2012. Accessed June 30, 2016. http://www.cdc.gov/parasites/sleepingsickness/gen_info/faqs-east.html. WAT is more commonly reported and tends to be a more chronic disease. Around 7000 to 10,000 new cases of WAT are identified each year. US Centers for Disease Control and Prevention, “Parasites – African Trypanosomiasis (also known as Sleeping Sickness), Epidemiology&Risk Factors,” 2012. Accessed June 30, 2016. http://www.cdc.gov/parasites/sleepingsickness/epi.html.