Browsing by Autor "Rajal, V B"

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Acanthamoeba in the eye, can the parasite hide even more? Latest developments on the disease.
(2018) Juárez, M M; Tártara, L I; Cid, A G; Real, J P; Bermúdez, J M; Rajal, V B; Palma, S D
Acanthamoeba spp. is a free living protozoan in the environment, but can cause serious diseases. Acanthamoeba keratitis (AK), a severe and painful eye infection, must be treated as soon as possible to prevent ulceration of the cornea, loss of visual acuity, and eventually blindness or enucleation. Although the disease affects principally contact lens (CLs) wearers, it is recognized nowadays as a cause of keratitis also in non-CLs wearers. Although the number of infections caused by these amoebae is low, AK is an emerging disease presenting an extended number of cases each year worldwide mostly due to the increasing use of CLs, but also to better diagnostic methods and awareness. There are two principal causes that lead to severe outcomes: misdiagnosis or late diagnosis of the causal agent, and lack of a fully effective therapy due to the existence of a highly resistant cyst stage of Acanthamoeba. Recent studies have reported different genotypes that have not been previously associated with this disease. In addition, Acanthamoeba can act as a reservoir for phylogenetically diverse microorganisms. In this regard, recently giant viruses called Pandoravirus have been found within genotypes producing keratitis. What potential risk this poses is not yet known. This review focuses on an overview of the present status and future prospects of this re-emerging pathology, including features of the parasite, epidemiology, clinical aspects, diagnosis, and treatment.
Infectivity and nucleic acid persistence of P22 and PP7 virus surrogates in synthetic water matrices under different environmental conditions.
(2026) Corimayo, S N; Maidana Kulesza, M N; Gutiérrez-Cacciabue, D; Rajal, V B; Poma, H R
The persistence of waterborne virus persistence in surface waters may pose a risk to human health. To assess their persistence and mitigate exposure risks in aquatic environments is essential to understand how they (or their surrogates) interact with suspended sediments under different environmental conditions. These sediment particles can adsorb viral particles, influencing their transport, sedimentation, and persistence in aquatic environments. This study evaluated the decay of two virus surrogates, P22 (DNA phage) and PP7 (RNA phage), for enteric DNA and RNA viruses, respectively, in water environments. The phages decay was analyzed using synthetic water matrices with two sediment concentrations (0.5, and 5 g/L), two temperatures (12 and 25 °C), and two electrical conductivities (130 and 1300 μS/cm). Kinetic parameters were calculated using a first-order decay model to estimate phage persistence. Both plaque assays and real-time PCR (qPCR) revealed longer phage persistence at 12 °C than at 25 °C. High sediment concentrations accelerated the decay of both infectious phages and nucleic acids, particularly at 25 °C. High electrical conductivity (1300 μS/cm) exerted a protective effect on PP7 at 25 °C, preserving infectivity and RNA integrity, while it had no impact on P22 persistence. P22 DNA persisted longer than infectious P22, whereas PP7 RNA exhibited similar behavior to infectious PP7. Manual resuspension of sediments resulted in only minor recovery of phages. The results suggest that both sediment and water chemistry must be considered when monitoring enteric viruses in aquatic environments. Additionally, qPCR-based approaches may be useful for studying RNA viruses, especially for viruses that are difficult or impossible to culture, providing complementary information on viral genome stability. However, for DNA viruses, combining culture-based and molecular assays is recommended to better understand decay patterns of both infectious particles and viral genomes. These findings, although limited to virus surrogates in synthetic water matrices, have important implications for designing monitoring strategies to control waterborne viral transmission.
Unraveling the causes of Salmonella paratyphi B endemicity in Salta: A clinical-environmental perspective.
(2026) Maidana Kulesza, M N; Rajal, V B; Sanguino Jorquera, D G; Romero, V L; Aparicio González, M; Leonardi, S; Campos, E E; Bracamonte, M E; Reynaga, N L; Zago, M P; Poma, H R
Salmonella Paratyphi B (SPB) has become endemic in the city of Salta, Argentina, with a staggering burden of bloodstream infections requiring hospitalization. This study unravels the underlying drivers of this endemicity through an integrated clinical-environmental approach. A novel duplex qPCR system was developed to accurately distinguish SPB from other Salmonella serotypes, enabling precise diagnosis and treatment. Clinical analysis revealed SPB in 98 % of positive blood cultures, confirming its strong association with severe infections. Contrary to initial hypotheses, the public drinking water network -supported by deep wells and systematic chlorination-showed negligible microbial contamination, ruling it out as the primary transmission route. Instead, environmental investigations uncovered widespread SPB in untreated wastewater, river water used for crop irrigation, and in leafy vegetables sold in local markets. SPB was detected in 40 % of lettuce, arugula, and celery samples during the rainy season, with contamination levels exceeding international safety standards by several orders of magnitude. This widespread presence of SPB in fresh produce, coupled with its uniform detection across city districts regardless of socioeconomic level, points to a foodborne route of transmission through contaminated vegetables. Based on these findings, we propose a strategic intervention plan that includes public education, routine screening for chronic carriers, strengthened monitoring of irrigation water, improved vegetable quality control, and upgrades to wastewater treatment infrastructure. This study highlights the importance of targeted, multidisciplinary approaches to address human-restricted pathogens and provides a roadmap for interrupting SPB transmission in endemic urban contexts.