Parasitic Infection of the Central Nervous System

Challenges associated with the diagnosis and treatment of parasitic encephalitis

“…Other neurological signs previously reported in the literature included cranial nerve deficits, seizures, ataxia (often asymmetrical) and recumbency (Jose-Cunilleras 2010). Horses affected with Halicephalobus-induced encephalomyelitis may also have concurrent renal disease or granulomatous swelling of the skin or head (Furr 2008;Jose-Cunilleras 2010). Based on the findings of an occupying mass lesion on computed tomography (CT) of the head and marked eosinophilic inflammation on CSF analysis, Wilford et al (2013) made a presumptive diagnosis of parasitic encephalitis.…”

“…However, it should be mentioned that an antemortem diagnosis is very difficult to confirm in the absence of accessible granulomatous lesions for biopsies (Hermosilla et al 2011). For instance, nonspecific signs of inflammation are often present on CSF analysis of horses affected with verminous encephalomyelitis while eosinophilia is rarely observed (Furr 2008). In addition, although eosinophilic pleocytosis is strongly suggestive of parasite infection, it has been reported during other conditions such as idiopathic eosinophilic meningoencephalitis in horses, lead poisoning in calves and salt toxicity in swine, as well as other noninfectious and infectious diseases in small animals (Loibl et al 2013;Wilford et al 2013).…”

“…fenbazole 50 mg/kg bwt per os once a day for 3 days) could be beneficial as described by Wilford et al (2013) and others (Lester 1992). It has also been proposed that ivermectin should not be used alone, but rather in combination with fenbazole, because of its questionable ability to cross the blood-brain barrier and its delayed parasitical activity (Furr 2008). Indeed, its has been suggested that anti-parasitic agents which provide a rapid kill should be used to minimise the progression damage (Furr 2008).…”

“…It has also been proposed that ivermectin should not be used alone, but rather in combination with fenbazole, because of its questionable ability to cross the blood-brain barrier and its delayed parasitical activity (Furr 2008). Indeed, its has been suggested that anti-parasitic agents which provide a rapid kill should be used to minimise the progression damage (Furr 2008). However, Wilford et al (2013) reported that the initial treatment with fenbazole may have resulted in an acute worsening of the clinical signs due to a strong inflammation response associated with parasitic death, although a direct cause-effect relationship could not be established.…”

“…Most modern anthelminthics have efficacy against the parasites that cause verminous encephalomyelitis (e.g. Halicephalobus gingivalis , Strongylus vulgaris , Hypoderma, Setaria ), although their ability to achieve effective concentration in the CNS and CSF and to penetrate granulomatous lesions of the CNS is unknown (Furr ). For instance, a high dose of benzimidazole (e.g.…”