Most of the drugs used for trichinellosis treatment showed a limited bioavailability, a high degree of resistance and a weak activity against encapsulated larvae. Therefore, there is an urgent need to develop new agents to improve the bioavailability of these drugs. So, the aim of the present study was to assess the use of chitosan (CH) nanoparticles alone or loaded with full and half dose albendazole (ABZ) to increase albendazole dissolution rate, to enhance its antiparasitic activity during the muscular phases of T. spiralis infection. Fifty male albino mice were used. They were divided into six experimental groups. Two control groups each includes five mice and four infected treated groups each includes ten mice. Chitosan nanoparticles were used orally at a dose of 100mg/kg/day starting from the 31 st -day post infection (dpi) for seven successive days either alone or loaded with full dose or half dose of ABZ. Results revealed a significant improvement in all treated groups with the highest reduction rate (97.3%) of muscle larval counts, improvement of muscular histopathological changes, and degeneration of encysted larvae with minimal pathologic changes of infected skeletal muscles. A significant decrease in inducible nitric oxide synthetize (iNOS) expression in muscle tissues was in mice treated by CH loaded with a full dose of ABZ compared to control group.

Background: COVID-19 is a worldwide pandemic that stroke almost all countries of the world causing thousands of deaths and disabilities and burdened the economy of countries. One of the main criteria of the immune response against COVID-19 is the “immune exhaustion”, due to increased expression of T cell suppressor molecules e.g. programmed death-1 (PD-1), that leads to flaring of viral multiplication and disastrous clinical outcomes. This immune exhaustion is not restricted to COVID-19 but is also a common complication of chronic infections with the widely spreading protozoan, Toxoplasma (T.) gondii. Thus, theoretically, the toxoplasmosis-associated immune exhaustion can worsen that of COVID-19 and consequently increases its severity. However, the studies on this theory are still insufficient. Objective: this work was designed to answer two questions. Does T. gondii co-infection affect the severity of COVID-19 manifestations? Is this action related to T. gondii-induced PD-1 changes? Methodology: Covid-19+ patients with moderate and severe conditions were screened for T. gondii IgG and compared to healthy controls. Serum levels of IL-1β, IL-6, TNFα, IFNγ, IL-1α cytokines were assessed to evaluate COVID-19 severity and prognosis. Lymphocytic expression of PD-1 was assessed by flowcytometry. Results: We recorded a higher incidence of toxoplasmosis among COVID-19 patients especially patients with severe/critical manifestations. T. gondii positive cases exhibited a statistically significant increase in lymphocytic expression of PD-1 that correlated positively with the proinflammatory and bad prognosis cytokines. With fixation of other risk factors for severity, toxoplasmosis still scored a significant value. Conclusion: toxoplasmosis increased the severity of COVID-19. These effects can be related to the Toxoplasmaassociated increased lymphocytic PD-1 expression. So, toxoplasmosis can be considered as an unrecognized independent risk factor for COVID-19 severity.

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