Isolation, Identification, and Determination of the Virulence of the Causal Agents of Corm Rot of Saffron (Crocus sativus L.) in Valle de Uco, Argentina.

Saffron (Crocus sativus L.) presents an attractive opportunity for diversifying production and adding value, particularly for small-scale growers and family-based agriculture. However, the agamic propagation of the crop through corms raises concerns regarding disease dispersion. During the summers of 2013 and 2015, symptoms of corm rot were observed in saffron crops in La Consulta, Valle de Uco, Argentina. These symptoms manifested in the form of wilting plants and red-coloured areas on the surface of the corms, in some cases affecting deeper regions. This study aimed to isolate and identify the causal agent responsible for saffron corm rot while also comparing the virulence of four strains isolated on saffron plants. Consistent isolation of Fusarium spp. colonies from affected corms confirmed its association with the disease. The obtained isolates were inoculated into healthy corms, and the reproduction of symptoms was confirmed, as well as subsequent pathogen re-isolation. Morphological and molecular characterisation of the strains was performed using rDNA gene sequencing. Furthermore, disease progression was assessed with fitting epidemiological models to empirical data, which served as estimators of fungal strain aggressiveness. The results conclusively identified Fusarium oxysporum Schltdl. as the causal agent of corm rot, and variations in virulence were observed among the strains on the host plant. After basic molecular and pathological studies, it is postulated that the fungal strains possibly belong to the forma specialis gladioli, but further studies are necessary to confirm that. The present study provides findings that highlight the importance of early detection and the preservation of pathogen-free fields to sustain saffron cultivation. These findings may constitute the initial step for future projects aimed at understanding the epidemiology of the disease better, determining the species/races of the pathogen, and developing effective management strategies.

Incidence of Guillain-Barré syndrome in an Uruguayan population. A prospective cohort study.

Guillain-Barre syndrome (GBS) is an acute autoimmune peripheral inflammatory neuropathy and the most frequent cause of non-poliovirus acute flaccid paralysis worldwide. Background annual GBS incidence rates (IRs) in Latin America (LA) varies from 0.40 to 2.12/100000 persons per year. We performed a prospective population-based epidemiological study to determine the incidence and clinical profile of GBS in the most densely populated regions in Uruguay. The incidence of GBS in the population living in Montevideo and Canelones was studied in the period between June 01, 2018 and May 31, 2020. Patients older than 16 years of age diagnosed with GBS were prospectively enrolled. The mean global annual IR in the Uruguayan population was 1.7/100000 persons (95% CI 1.25-2.25). The highest rate was observed in the 65 to 74 age group among men (5.25/100000 per year) and in the 55 to 64 age group among women (2/100.000 per year). The mean age was 53.9 ± 19.5, years, without difference by sex (53.5 women, 54.5 men). The in-hospital mortality rate was 5.8%. A total of 51 patients were diagnosed with GBS: 42 (82%) had typical GBS, 5 (10%) Miller-Fisher syndrome (MFS), 3 (7%) a bilateral facial nerve palsy, 1 patient had a GBS-MFS overlap (2.3%). This is the first population-based GBS incidence study in LA using a prospective design. Our IR can be a useful tool in establishing the background rate to examine future disease trends caused by the introduction of new viruses or vaccines in Uruguay.