The complicated pathophysiological and immunological changes in the central nervous system of patients with neurocysticercosis produce a variety of signs and symptoms, which complicate the clinical and surgical management of this disease. A complete and objective classification is needed, to improve the medical approach as a whole. We studied 336 patients, in whom we classified neurocysticerosis according to criteria of viability and location of the parasite in the CNS: active form (37.2%) when the cysticercus is alive, transitional form (32.8%) when it is in the degenerative phase, and inactive form (30%) when the parasite is dead. This classification establishes the correlation between the different forms of neurocysticerosis and its clinical manifestations, and can be used for planning therapeutic strategies.Resume: La neurocysticerose : ebauche de classification. Les changements physiopathologiques et immunologiques complexes du systeme nerveux central chez les patients atteints de neurocysticercose donnent lieu a des signes et a des symptomes varies qui compliquent le traitement clinique et chirurgical de cette maladie. Nous avons besoin d'une classification complete et objective de la neurocysticercose afin d'ameliorer l'approche medicale globale. Nous avons etudie 336 patients atteints de neurocysticercose, dont nous avons classifie la maladie selon des criteres de viabilite et de localisation du parasite dans le systeme nerveux central : la forme active (37.2%) quand le cysticerque est vivant, la forme transitionnelle (32.8%) quand le parasite est en phase degenerative et la forme inactive (30%) quand le parasite est mort. Cette classification etablit la correlation entre les differentes formes de neurocysticercose et leurs manifestations cliniques et peut etre utilisee pour planifier des strategies therapeutiques.Can. J. Neurol. Sci. 1994; 21: 43-47 Human cysticercosis, or larval stage of the Taenia solium, is the most common parasitic illness that affects the central nervous system (CNS), especially in countries where the sanitary infrastructure is deficient. In Latin American countries, the frequency of neurocysticercosis (NC) is very high, reaching 3.6% in some regions, 1 and it is becoming increasingly common in developed countries, because of immigration from endemic regions. 2 We find it even in communities which do not eat pork and whose residents have not traveled to a country where T. solium infection is endemic.3 Since NC is a great public health problem, it is important to have a clear understanding of this disease in order to implement the necessary preventive measures.The natural history of the cysticercus in the CNS is, to date, not completely known; however, the CT scan in the last decade, and now the MRI, 4 have been very useful in the study of the biologic evolution of the cysticercosis in the CNS, especially in the brain parenchyma. Many authors have described the CT appearance of parenchymal lesions of NC related to the stage of the larva.5-9 When the larva is alive, the ...
Previous reports of favorable response to treatment of neurocysticercosis with either praziquantel or albendazole are by no means definitive and may be a reflection of the natural history of the condition. The present study, with randomized treatment assignment and including a control group, raises questions as to what extent and in whom treatment with these drugs is effective, and suggests that treatment with antihelminthic agents may be associated with an increased frequency of long-term sequelae.
Biological characteristics of 11 Potato virus S (PVS) isolates from three cultivated potato species (Solanum spp.) growing in five Andean countries and 1 from Scotland differed in virulence depending on isolate and host species. Nine isolates infected Chenopodium quinoa systemically but two others and the Scottish isolate remained restricted to inoculated leaves; therefore, they belonged to biologically defined strains PVSA and PVSO, respectively. When nine wild potato species were inoculated, most developed symptomless systemic infection but Solanum megistacrolobum developed systemic hypersensitive resistance (SHR) with one PVSO and two PVSA isolates. Andean potato cultivars developed mostly asymptomatic primary infection but predominantly symptomatic secondary infection. In both wild and cultivated potato plants, PVSA and PVSO elicited similar foliage symptoms. Following graft inoculation, all except two PVSO isolates were detected in partially PVS-resistant cultivar Saco, while clone Snec 66/139-19 developed SHR with two isolates each of PVSA and PVSO. Myzus persicae transmitted all nine PVSA isolates but none of the three PVSO isolates. All 12 isolates were transmitted by plant-to-plant contact. In infective sap, all isolates had thermal inactivation points of 55 to 60°C. Longevities in vitro were 25 to 40 days with six PVSA isolates but less than 21 days for the three PVSO isolates. Dilution end points were 10−3 for two PVSO isolates but 10−4 to 10−6 with the other isolates. Complete new genome sequences were obtained from seven Andean PVS isolates; seven isolates from Africa, Australia, or Europe; and single isolates from S. muricatum and Arracacia xanthorhiza. These 17 new genomes and 23 from GenBank provided 40 unique sequences; however, 5 from Eurasia were recombinants. Phylogenetic analysis of the 35 nonrecombinants revealed three major lineages, two predominantly South American (SA) and evenly branched and one non-SA with a single long basal branch and many distal subdivisions. Using least squares dating and nucleotide sequences, the two nodes of the basal PVS trifurcation were dated at 1079 and 1055 Common Era (CE), the three midphylogeny nodes of the SA lineages at 1352, 1487, and 1537 CE, and the basal node to the non-SA lineage at 1837 CE. The Potato rough dwarf virus/Potato virus P (PVS/PRDV/PVP) cluster was sister to PVS and diverged 5,000 to 7,000 years ago. The non-SA PVS lineage contained 18 of 19 isolates from S. tuberosum subsp. tuberosum but the two SA lineages contained 6 from S. tuberosum subsp. andigena, 4 from S. phureja, 3 from S. tuberosum subsp. tuberosum, and 1 each from S. muricatum, S. curtilobum, and A. xanthorrhiza. This suggests that a potato-infecting proto-PVS/PRDV/PVP emerged in South America at least 5,000 years ago, became endemic, and diverged into a range of local Solanum spp. and other species, and one early lineage spread worldwide in potato. Preventing establishment of the SA lineages is advised for all countries still without them.
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