Neurocysticercosis: Neurology and neurobiology

Abstract

Neurocysticercosis, the most common parasitic brain disease worldwide, is due to the larvae infestation of Taenia solium. It is an endemic, neglected disease in poor countries with deprived sanitation, and is increasingly being reported in wealthy countries due to migration. Humans are the only definitive host of T. solium, while pigs are the intermediate hosts. Humans may become intermediate host by ingesting food or water contaminated by T. solium eggs.Infection is associated with local and systemic immune-inflammatory responses modulated by the developmental stage of the parasite in the host (vesicular, colloidal. granular-nodular, and calcified stages) and by the central nervous system compartment where the parasites are located. Genetic diversity of cysticerci has been studied and the genome of T. solium is currently being sequenced.The clinical manifestations are heterogeneous and depend mainly on the localization of cysts and immune response to the host. Seizures, headache, focal deficits and cognitive abnormalities are the most frequent manifestations. The prognosis is good; nevertheless, it may lead to long-term neurological sequels such as epilepsy and hydrocephalus.Diagnosis is made mainly by neuroimaging, which is useful in the detection of evolutionary stage, number and localization of cysts. Immunological testing can be helpful; nonetheless, a negative test does not rule out the diagnosis. Treatment is complex and should be individualized, based on location and viability of the parasites. In most cases treatment is only symptomatic. Antihelminthic drugs are effective in approximately one-third of patients with parenchymal viable cysts. The most effective approach to Taeniasis/cysticercosis is prevention. This should be a primary public health focus for poor countries.