Neurocysticercosis: parasitology, clinical presentation, diagnosis, and recent advances in management.
Cysticercosis, which is the most common parasitic cause of neurological disease in man, consists of infection by the larval stage (Cysticercus cellulosae) [1] of the pig tapeworm Taenia solium. The disease was described in pigs by Aristophanes and Aristotle in the third century BC, but Paranoli is credited with the first human account (involving the corpus callosum) in 1550 [2]. The term cysticercus was first used by Laennec. One of the largest series of cases was documented by Dixon and Lipscomb in British soldiers and their families in India [3]; 92 per cent of 450 affected individuals described had a history of epilepsy. Although accurate information on prevalence rates is rarely available, the disease is known to be endemic in all continents with the exception of Australasia [4]; however, even there cases in immigrants are now being identified. Exceptionally high rates exist in Latin America-from Mexico to Chile. In Mexico City 1.4—3.6 per cent of autopsies in the general population provide evidence of cysticercosis [1]; the disease accounts for approximately 10 per cent of neurological admissions, as well as up to one-third of craniotomies for intracranial space-occupying lesions. Important foci exist in the USSR, China, India, Pakistan, the Philippines and Indonesia [5], and the disease occurs sporadically throughout Africa. Although now rare in northern Europe, it remains a problem in the Iberian peninsula and the Slavic countries. In north America, the disease is overall unusual; however, during the last decade it has become a significant problem in immigrant populations [6]. Cysticercosis is overall unusual in Jews and Muslims because pork consumption in these ethnic groups is generally low; however, this fact does not prevent ingestion of T. solium eggs in contaminated food or water. This, and not uncooked pork ingestion is the cause of human cysticercosis. The highest prevalence rates therefore exist in communities where there is a close contact between man and pigs, pork is eaten raw or undercooked, and most importantly where hygienic standards and practices are low. Affected communities are often rural ones [5]. Faecal contamination of foodstuffs is the usual source of infection; however flies have been shown to play a