BackgroundQatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess the proportions of ever and/or current infection in this population.MethodsA cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and polymerase chain reaction (PCR) positivity through PCR testing. Associations with antibody and PCR positivity were identified through regression analyses.ResultsStudy included 2,641 participants, 69.3% of whom were <40 years of age. Anti-SARS-CoV-2 positivity was estimated at 55.3% (95% CI: 53.3-57.3%) and was significantly associated with nationality, geographic location, educational attainment, occupation, presence of symptoms in the two weeks preceding the survey, and previous infection diagnosis. PCR positivity was assessed at 11.3% (95% CI: 9.9-12.8%) and was significantly associated with geographic location, contact with an infected person, and reporting two or more symptoms. Infection positivity (antibody and/or PCR positive) was assessed at 60.6% (95% CI: 9.9-12.8%). The proportion of antibody-positive CMWs that had a prior SARS-CoV-2 diagnosis was 9.3% (95% CI: 7.9-11.0%). Only seven infections were ever severe and one was ever critical—an infection severity rate of 0.5% (95% CI: 0.2-1.0%).ConclusionsSix in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or minimally mild infections.

Cirrhosis is a chronic liver disease. The present work aimed to evaluate the regulatory immune effect of curcumin in hepatic cirrhosis induced by carbon tetrachloride (CCl4) injections in experimental rats’ model. Chronic liver fibrosis was induced in experiment animals by recurrent injections of CCl4 for more than 5 weeks. They were divided into five groups: first group was injected with normal saline, second group with CCl4, third, fourth, and fifth groups were injected with CCl4 (intraperitoneal injection) at dose 3 ml/kg, two times weekly for 6 weeks supplemented with the administration of curcumin with concentrations 250, 200, and 150 mg/kg. Immune response was analyzed to different treatments. Interleukin 10 (IL‐10), pro‐inflammatory cytokines TNF‐α, TGF‐1β, and liver histopathological examinations were conducted. The results showed that estimations of IL‐10 concentrations were significantly increased in curcumin groups compared with CCl4 group, whereas TNF‐α and TGF‐1β levels were significantly decreased comparing with CCl4 group. The histopathological examinations for liver tissues showed that curcumin treated groups have almost retained the normal structure of liver tissues. In conclusion, curcumin inhibited hepatic fibrosis and liver fibrogenesis with regulation of the immune system mechanism against invader chemical toxicity. Practical applications Curcumin is well documented for its medicinal properties, commonly used as a spice. Our work has thus demonstrated its effectiveness as an immunomodulatory agent. Practically, clinical studies have suggested that curcumin displays a diverse and powerful array of pharmacological effects in nearly all of the human body's major organ systems. These are: antidiabetes, anti‐inflammatory, anticancer, antiaging, antioxidant, antibacterial infection, hepatoprotective, neurodegenerative, and cardiovascular effects.

The current work estimated the antitumour efficacy of melatonin (MLT) on the growth of Ehrlich ascites carcinoma cells inoculated intramuscularly into the hind limbs of female BALB/c mice and to compare its effects with those of adriamycin (ADR). After solid tumours developed, the animals were divided into the three following groups: the tumour‐bearing control, MLT‐treated (20 mg/kg body weight) and ADR‐treated (10 mg/kg body weight) groups. The results showed a significant reduction in the tumour masses of the treated animals in comparison with those of the control group. There were a significant decrease in the malondialdehyde level and a significant elevation of the glutathione concentration and the superoxide dismutase and catalase activities in the MLT and ADR groups. The current study indicated the increased expression levels of P53, caspase‐3 and caspase‐9 and the decreased expression levels of the rRNA and Bcl2. The MLT and ADR treatments resulted in histological changes, such as a marked degenerative area, the necrosis of neoplastic cells, the appearance of different forms of apoptotic cells and giant cells with condensed chromatin, and a deeply eosinophilic cytoplasm. The MLT and ADR treatments also significantly decreased the Ki‐67 protein and vascular endothelial growth factor (VEGF) expression levels in the tumour masses. In conclusion, similar to ADR‐treated tumour‐bearing mice, MLT suppressed the growth and proliferation of tumour by inducing apoptosis and by inhibiting tumour vascularization. The current data recommend MLT as a safe natural chemotherapeutic adjuvant to overcome cancer progression after a clinical trial validates these results.

The current study evaluated the immunomodulatory effects of Carica papaya pulp and seeds methanol (MeOH) extracts on mice infected with Listeria monocytogenes. Gas chromatography–mass spectrometry analysis identified 10 active constituents in C. papaya seed MeOH extract and 10 compounds in C. papaya pulp MeOH extract. The experimental animals were divided into negative control (G1) group, positive control (G2) group, pulp extract treated (G3) group, and seed extract treated (G4) group. After infection of animals (G2, G3, and G4), treatments were started for 3 weeks. Estimation of the immunological parameters showed a marked decrease in IgM levels and an increase in IgG levels in the treated groups (G3 and G4) compared with those in G2. The proinflammatory cytokines (IL‐10, IL‐12, IL‐1β, IL‐6, and TGF‐β1) were decreased in the treated groups (G3 and G4) compared with those in G2. Nitric oxide levels were also decreased, and the percentages of phagocytosis increased compared with those of G2. The results demonstrated the immunomodulatory and anti‐inflammatory effects of C. papaya pulp and seeds MeOH extracts. Practical applications Based on the antioxidant and antibacterial activities exhibited by the pulp and seed MeOH extracts investigated in this study, Carica papaya might be considered as a natural source of phytochemicals that could be utilized in novel foods and pharmaceuticals. Further investigation are needed to identify and purify compounds that might be responsible for the observed effects.