Background By 27 June 2020, almost half a million people had died due to COVID-19 infections. The susceptibility and severity of infection vary significantly across nations. The contribution of chronic viral and parasitic infections to immune homeostasis remains a concern. By investigating the role of interferon (IFN)-γ, we conducted this study to understand the connection between the decrease in numbers and severity of COVID-19 cases within parasitic endemic regions. Our research included 375 patients referred to hospitals for diagnosis of COVID-19 infection. Patients were subjected to full investigations, in particular severe acute respiratory syndrome coronavirus-2 nucleic acid and Toxoplasma IgM and IgG antibody detection, stool examination, and quantitative IFN-γ measurement. Results The majority of the studied cases had chest manifestation either alone (54.7%) or in association with gastrointestinal (GIT) manifestations (19.7%), whereas 25.6% had GIT symptoms. We reported parasitic infections in 72.8% of mild COVID-19 cases and 20.7% of severe cases. Toxoplasma gondii, Cryptosporidium, Blastocyst, and Giardia were the most common parasitic infections among the COVID-19 cases studied. Conclusion The remarkable adaptation of human immune response to COVID-19 infection by parasitic infections with high levels of IFN-γ was observed in moderate cases compared with low levels in extreme cases. The potential therapeutic efforts aimed at the role of parasitic infection in immune system modulation are needed if this hypothesis is confirmed.

Hepatic affection by granulomatous inflammation in schistosomiasis suggested that a potential anti-pathology vaccine could be generated based on limiting the presence of hazardous hepatocytes induced apoptosis and caused reduction of granulomas number and size . So, this work is concerned with experimental assessment of the efficacy of different antigens (SEA, SWAP and combined SEA and SWAP) on murine liver after challenge by infection, histopathological, histochemical and molecular investigations were performed on sixty male laboratory bred Swiss Albino mice. A schedule of vaccination and challenge infection was followed and performed on 6 mice groups (each of ten); control normal (G1), control infected (G2), adjuvant received then infected (G3), SEA + adj. received then infected (G4), SWAP + adj. received then infected (G5) and SEA + SWAP + adj. received then infected (G6).Animals were euthanized 10 weeks post infection.Vaccination efficacy was assessed by histopathological, histochemical and molecular studies on murine hepatic tissues.Results showed that:The combined (SEA + SWAP) antigens were better in reducing the number and diameter of the hepatic granulomas, with more protection of the hepatocytes DNA, in addition to more decrease of hepatocytes induced apoptosis and fragmentation as demonstrated by molecular assay.

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Trichinellosis is a zoonotic disease that endangers human health and can lead to death. Restricted absorption and poor results of conventional therapies demand new effective natural remedies to treat both enteral and parenteral trichinellosis. This study assessed the antiparasitic and anti-inflammatory effects of Citrus limon and Capsicum frutescens on murine trichinellosis and compared them with those of albendazole and prednisolone, which are conventionally used to treat trichinellosis. Overall, 50 Swiss albino male mice were divided into five groups, with ten mice in each group: negative control, positive control, albendazole combined with prednisolone, C. limon, and C. frutescens. Mice were sacrificed 7 and 35 days after infection, for intestinal and muscular phase analyses. Drug efficacies were parasitologically, biochemically, histopathologically and ultrastructurally assessed. Our results demonstrated the efficacy of C. frutescens and C. limon extracts as antiparasitic agents, showing a substantial decrease in adult and larval counts. Moreover, both extracts had the ability to decrease serum tumour necrosis factor-α levels during the intestinal and muscular phases. In addition to the improved histopathological changes in the small intestine and muscles, the destructive effects on adults and larvae were ultrastructurally evident on transmission electron microscopy. In conclusion, C. frutescens and C. limon extracts are promising remedies for the treatment of experimental trichinellosis, particularly, the C. frutescens extract.

Background: Trichinella spiralis causes trichinosis through ingestion of pork contaminated by its infective larvae, resulting in intestinal and muscular phases of infection in the same host. Stem cells (SCs) treat some diseases due to their capacity for trans-differentiation and immunomodulation. Objective: To assess the therapeutic impact of mesenchymal stem cells (MSCs) during intestinal and muscular stages in T. spiralis-experimentally infected mice; used alone as monotherapy or combined with mebendazole (MBZ). Material and Methods: Forty albino mice were used to obtain bone marrow MSCs. Another 100 albino mice were divided into 2 groups 50 mice each simulating intestinal (a) and muscular (b) phases. Each group was further subdivided into 5 subgroups, 10 mice each as follows: G1a and G1b: negative non infected control; G2a and G2b: positive infected control; G3a and G3b: infected and MBZ treated; G4a and G4b: infected and MSCs tested; and G5a and G5b: infected and combined MBZ and MSCs therapy tested. Mice of intestinal phase were sacrificed on 7 th day post-infection (PI) while mice of muscular phase were sacrificed on 49 th day PI. Assessment was done by parasitological assessment (the number of adult worms in the intestine in groups (a) and the number of encysted larvae in the diaphragm in groups (b); histopathological and histochemical assessment of all groups using hematoxylin and eosin (H&E) and Feulgen stains of different mice tissues and ultrastructural assessment using transmission electron microscope (TEM). Results: The combined therapy was potent; it showed the highest significant reduction in the number of intestinal worms and encysted muscular larvae with preservation of the different tissues elements as investigated by different stains and TEM. Conclusion:MSCs can be used as additive/synergistic therapy in the treatment of trichinosis.

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