Mapping the global distribution of Strongyloides stercoralis and hookworms by ecological niche modeling.

BACKGROUND: The WHO has established a control strategy for Strongyloides stercoralis in school-aged children as well as targets and to maintain control programs for Ascaris lumbricoides, Trichuris trichiura and hookworms. For an efficient development of control programs, it is necessary to know the target countries around the world, as well as the areas within each country where efforts should be focused. Therefore, maps that provide information on the areas at risk for soil-transmitted helminth (STH) infections on a national and sub-national scale would allow for a better allocation of resources. METHODS: We used the ecological niche models MaxEnt and Kuenm R library to estimate the global distribution of S. stercoralis and hookworms. We used occurrence points of both species extracted from surveys of two literature reviews and from the Global Atlas of Helminth Infection database, together with 14 raster maps of environmental variables. RESULTS: We obtained two raster maps with the presence probability of S. stercoralis and hookworm infections at a global level and then estimated the global population at risk to be 2.6 and 3.4 billion, respectively. The population at risk was also estimated at the country level using estimations for areas as small as 25 km2. A relationship was found between the probability of the presence of S. stercoralis and its prevalence, and a raster map was generated. Annual precipitation, annual temperature, soil carbon content and land cover were the main associated environmental variables. The ecological niches of Strongyloides stercoralis and hookworms had an overlap of 68%. CONCLUSIONS: Here we provide information that can be used for developing more efficient and integrated control strategies for S. stercoralis and hookworm infections. This information can be annexed to the study of other risk factors or even other diseases to assess the health status of a community. GRAPHICAL ABSTARCT.

Antiviral effect of high-dose ivermectin in adults with COVID-19: A proof-of-concept randomized trial.

BACKGROUND: There are limited antiviral options for the treatment of patients with COVID-19. Ivermectin (IVM), a macrocyclic lactone with a wide anti-parasitary spectrum, has shown potent activity against SARS-CoV-2 in vitro. This study aimed at assessing the antiviral effect of IVM on viral load of respiratory secretions and its relationship with drug concentrations in plasma. METHODS: Proof-of-concept, pilot, randomized, controlled, outcome-assessor blinded trial to evaluate antiviral activity of high-dose IVM in 45 COVID-19 hospitalized patients randomized in a 2:1 ratio to standard of care plus oral IVM at 0·6 mg/kg/day for 5 days versus standard of care in 4 hospitals in Argentina. Eligible patients were adults with RT-PCR confirmed SARS-CoV-2 infection within 5 days of symptoms onset. The primary endpoint was the difference in viral load in respiratory secretions between baseline and day-5, by quantitative RT-PCR. Concentrations of IVM in plasma were measured. Study registered at ClinicalTrials.gov: NCT04381884. FINDINGS: 45 participants were recruited (30 to IVM and 15 controls) between May 18 and September 9, 2020. There was no difference in viral load reduction between groups but a significant difference was found in patients with higher median plasma IVM levels (72% IQR 59-77) versus untreated controls (42% IQR 31-73) (p = 0·004). Mean ivermectin plasma concentration levels correlated with viral decay rate (r: 0·47, p = 0·02). Adverse events were similar between groups. No differences in clinical evolution at day-7 and day-30 between groups were observed. INTERPRETATION: A concentration dependent antiviral activity of oral high-dose IVM was identified at a dosing regimen that was well tolerated. Large trials with clinical endpoints are necessary to determine the clinical utility of IVM in COVID-19. FUNDING: This work was supported by grant IP-COVID-19-625, Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación, Argentina and Laboratorio ELEA/Phoenix, Argentina.

Corrigendum to Antiviral effect of high-dose ivermectin in adults with COVID-19: A proof-of-concept randomized trial [EClinicalMedicine 37 (2021) 100,959]".

[This corrects the article DOI: 10.1016/j.eclinm.2021.100959.].

The Strongyloides stercoralis-hookworms association as a path to the estimation of the global burden of strongyloidiasis: A systematic review.

TRIAL REGISTRATION: PROSPERO (registration code CRD42019131127).

Antioxidant enzymes and their modification under oxidative stress conditions

There are many cellular defense strategies against processes mediated by active oxygen species, including scavenger molecules and the enzymes catalase, superoxide dismutase and glutathione peroxidase. The activity of these antioxidant enzymes allows to keep O2- and H2O2 steady state concentrations at low levels, compatible with cell function. In most pathologies considered, modifications in levels of enzymatic activity have been observed in relation to values of control patients. Both increased and decreased levels have been found and in almost all systems the response of the three enzymes has been parallel. Different models of chronic treatment have also been considered. Parallel variations could be noted again regarding the antioxidant activity of these three enzymes. Moreover, there exists a correlation between the increase in the enzymatic activities and the acquired protection by treatment with barbital as reflected by the measured values of spontaneous chemiluminescence. on the other hand, increased levels of chemiluminescence in liver homogenates and diminished enzymatic activities were found in other experimental models. The response to these treatments is not the same in different organs since the rates of production of active oxygen species as well as the antioxidant defense activities are different in each organ. Finally, data of acute models of oxidative stress were compiled. Some of them have shown a biphasic response. At first a decrease in levels of enzymatic activities could be seen in response to the injury. Afterwards, an increase in the activity of the antioxidant enzymes followed as a consequence of an enzymatic induction or activation.