Safety and Efficacy of Direct Oral Anticoagulant in Addition to Antiplatelet Therapy After Acute Coronary Syndrome: A Systemic Review and Meta-analysis of 53,869 Patients.

INTRODUCTION: Significant progress has been made in the management of patients with acute coronary syndrome (ACS) during the past few decades. However, the role of direct oral anticoagulants (DOACs) in post-ACS prophylactic therapy remains unknown. This study aims to assess the efficacy and safety of DOACs plus antiplatelet treatment (APT) after ACS. METHODS: A systematic literature search was conducted to identify randomized clinical trials comparing DOACs plus APT with APT alone after ACS. The primary efficacy end points were cardiovascular mortality, myocardial infarction, all-cause mortality, and stroke and systemic embolization (SSE). The primary safety end point was major bleeding. The random-effects model was used to calculate relative risk (RR) and corresponding 95% CIs. RESULTS: Nine trials with a total of 53,869 patients were identified, with 33,011 (61.2%) in the DOACs plus APT group and 20,858 (38.8%) in the APT alone group. The use of DOACs did not decrease the risk of cardiovascular death (RR = 0.87; 95% CI, 0.75-1.01; P = 0.08; I2 = 0%) or myocardial infarction (RR = 0.90; 95% CI, 0.80-1.02; P = 0.10; I2 = 6%). However, the risk of SSE was significantly lower in patients who received DOACs plus APT compared with APT alone (RR = 0.67; 95% CI, 0.50-0.90; P = 0.008). Moreover, all-cause mortality was significantly lower in the DOACs plus APT group (RR = 0.83; 95% CI, 0.71-98; P = 0.03; I2 = 0%). However, the risk of major bleeding was significantly higher in patients treated with DOACs plus APT compared with APT alone (RR = 2.53; 95% CI, 1.96-3.26; P < 0.01; I2 = 0%), as was the risk of nonmajor bleeding (RR = 2.27; 95% CI, 1.51-3.41; P < 0.01). IMPLICATIONS: DOACs plus APT for the prevention of left ventricular thrombus in patients with ACS were associated with a lower risk of SSE and all-cause mortality but increased the risk of major and nonmajor bleeding. The benefits and risks of this approach should be weighed based on a patient's individual clinical characteristics.

Body Mass Index and Outcomes of Transcatheter Aortic Valve Replacement: A Retrospective Observational Study.

The influence of body mass index (BMI) on Transcatheter Aortic Valve Replacement (TAVR) outcomes has been the focus of several previous studies. In this study, we examined the relationship between BMI and various clinical outcomes following TAVR procedures. A comprehensive analysis was conducted using a large cohort of patients who underwent TAVR. In this study, we identified patients who underwent Transcatheter aortic valve replacement (TAVR) in the year 2020. Procedure Classification System (ICD-10-PCS) codes were used to identify TAVR cases. The weighted final study sample included 77319 TAVR hospitalizations. Patients were categorized into 5 groups based on their Body Mass Index (BMI. Our findings revealed that there was no significant difference in in-hospital mortality among different BMI groups when compared to patients with a normal BMI (20 to 24.9). patients with a BMI of 25 or higher demonstrated a statistically significant shorter duration of hospitalization compared to those with a normal BMI. patients with a BMI ranging between 30 and 39.9 exhibited decreased hospitalization costs when compared to patients with a normal BMI. Moreover, our study revealed a decrease in atrial fibrillation, acute heart failure and acute kidney injury complications following TAVR in patients with above-normal BMI. Despite similar in-hospital mortality across BMI groups, having a BMI of 25 or greater is associated with improved immediate outcomes following TAVR. These benefits in overweight and obese patients are consistent with findings described in recent literature. Further studies are warranted to explore the underlying mechanisms and potential implications of these associations, as well as to optimize patient selection and management strategies for TAVR procedures.

The Challenges of Caring for an Adult Child with Schizophrenia in the Family: An Analysis of the Lived Experiences of Older Parents.

The present study aimed to investigate the lived experiences of older parents regarding the challenges in caring for adult children with schizophrenia. The current study was conducted on 16 parental (mother or father) caregivers of adult children with schizophrenia using a descriptive phenomenological qualitative approach and Colaizzi's seven-step method. This study follows the Qualitative Research Checklist (COREQ). The findings showed that the parent caregivers' experiences could be classified into two main themes: "burden of care" and "Negative attitude and inefficient performance." The former consisted of three sub-themes including "disrupted social and family interactions," "helplessness and inefficient support," and "challenges of the healthcare system," while the latter had two sub-themes including "Negative attitude and inefficient performance of the caregivers" and "Negative attitude and inefficient performance of families and society." Older parents have to tolerate a significant burden of care due to their age and physical conditions. Improving the knowledge of specialists, the government's redoubled efforts in multifaceted support for patients and caregivers, creating an integrated team of specialists, and accepting and improving public attitudes against stigma and obvious discrimination in society as important priorities in improving the condition of caregivers and patients with schizophrenia were considered.

Comparative transcriptome analysis of synthetic and common wheat in response to salt stress.

Salt stress reduces wheat yield. Therefore, improvement for enhanced salt stress tolerance is necessary for stable production. To understand the molecular mechanism of salt tolerance in common wheat and synthetic hexaploid (SH) wheat, RNA sequencing was performed on the roots of three wheat lines salt-tolerant SH wheat, salt-tolerant common wheat, and salt-sensitive common wheat. Differentially expressed genes (DEGs) in response to salt stress were characterized using gene ontology enrichment analysis. Salt tolerance in common wheat has been suggested to be mainly regulated by the activation of transporters. In contrast, salt tolerance in SH wheat is enhanced through up-regulation of the reactive oxygen species signaling pathway, other unknown pathways, and different ERF transcription factors. These results indicate that salt tolerance is differentially controlled between common wheat and SH wheat. Furthermore, QTL analysis was performed using the F2 population derived from SH and salt-sensitive wheat. No statistically significant QTL was detected, suggesting that numerous QTLs with negligible contributions are involved in salt tolerance in SH wheat. We also identified DEGs specific to each line near one probable QTL. These findings show that SH wheat possesses salt tolerance mechanisms lacking in common wheat and may be potential breeding material for salt tolerance.

A mathematical model for SARS-CoV-2 in variable-order fractional derivative.

A new coronavirus mathematical with hospitalization is considered with the consideration of the real cases from March 06, 2021 till the end of April 30, 2021. The essential mathematical results for the model are presented. We show the model stability when R 0 < 1 in the absence of infection. We show that the system is stable locally asymptotically when R 0 < 1 at infection free state. We also show that the system is globally asymptotically stable in the disease absence when R 0 < 1 . Data have been used to fit accurately to the model and found the estimated basic reproduction number to be R 0 = 1.2036 . Some graphical results for the effective parameters are drawn for the disease elimination. In addition, a variable-order model is introduced, and so as to handle the outbreak effectively and efficiently, a genetic algorithm is used to produce high-quality control. Numerical simulations clearly show that decision-makers may develop helpful and practical strategies to manage future waves by implementing optimum policies.

Human Leukocyte Antigen B27 (HLA-B27) in the General Population in the Kingdom of Saudi Arabia.

BACKGROUND: Determining the prevalence of the human leukocyte antigen B27 (HLA-B27) in the general population in the Kingdom of Saudi Arabia. METHODS: This cross-sectional study was performed at King Abdulaziz University in the period May 23, 2019 - August 31, 2019 and included four hundred Saudi healthy blood donor subjects (200 male [50%]). We used blood samples in ethylenediaminetetraacetic acid (EDTA) tubes. The HLA-B27 alleles were detected by the Single Specific Primer-Polymerase Chain Reaction (SSP-PCR) using the HLA-B27 Screen Real Time kit from BioDiagene S.R.L (Palermo, Italy). Data analysis was achieved by the statistical package for social science (IBM SPSS Inc., version 20). RESULTS: Ten (2.5%) were positive for HLA-B27 (6 female [60.00%]). HLA-B27 positivity in blood groups was 3% in O and B, 1.7% in A, nil in AB but almost equal in Rh+ve (2.5 %) and Rh-ve (2.4 %) blood groups, with no significant difference neither between male and female (p = 0.52), nor between blood groups (p = 0.77). CONCLUSIONS: The prevalence of 2.5% for HLA-B27 in the general Saudi population was similar to that of Omair et al. using samples of Saudi cord blood [14]. The positivity in females was 1.5 times higher than in males. No correlation was seen between HLA-B27 and gender and blood groups.

Molecular mechanisms of anticancer activities of polyphyllin VII.

Cancer is the leading cause of mortality in the world. The major therapies for cancer treatment are chemotherapy, surgery, and radiation therapy. All these therapies expensive, toxic and show resistance. The plant-derived compounds are considered safe, cost-effective and target cancer through different pathways. In these pathways include oxidative stress, mitochondrial dependent and independent, STAT3, NF-kB, MAPKs, cell cycle, and autophagy pathways. One of the new plants derived compounds is Polyphyllin VII (PPVII), which target cancer through different molecular mechanisms. In literature, there is a review gap of studies on PPVII; therefore in the current review, we summarized the available studies on PPVII to provide a base for future research.

Small intestinal bacterial overgrowth among patients with celiac disease unresponsive to a gluten free diet.

BACKGROUND/AIMS: Little is known about the relationship between small intestinal bacterial overgrowth (SIBO) and celiac disease (CeD) in patients who are unresponsive to a gluten-free diet (GFD). This study aimed to determine the SIBO prevalence in patients with CeD who are unresponsive to a GFD. MATERIALS AND METHODS: We conducted a case-control study from July 2012 to September 2014. We included 32 patients with CeD who were unresponsive to a GFD and 52 healthy age- and sex-matched controls. Demographic, clinical, and laboratory data were obtained from patients' medical records. Antitissue transglutaminase antibody determined by enzyme-linked immunosorbent assay was recorded, and lactulose hydrogen breath test (LHBT) was used to detect SIBO in all participants. Microbiological analysis, including jejunal aspirates obtained using upper endoscopy, was performed for only 20 patients with CeD. RESULTS: A total of 10 (31%) of 32 patients with CeD and 4 (7.7%) of 52 controls tested positive for LHBT, with a statistically significant difference (p=0.007). Of 20 cultures, 3 (15%) were positive with no statistically significant correlation between the cultures and LHBT (p=0.05). In a subgroup analysis of children who were 18 years old or younger, 7/24 (29.2%) patients with CeD had a positive LHBT compared with 3/32 (9.4%) controls, but this difference was not statistically significant (p=0.08). CONCLUSION: The prevalence of SIBO was 31% in unresponsive patients with CeD according to LHBT and 15% in the quantitative culture of the jejunal aspirate, which is comparable with the published Western literature.

Investigation of Relationship between Family Social Support and the Level of Stigma Perceived by PLWHA in Iran.

This study is aimed to investigate the relationship between family social support and the level of stigma perceived by people living with HIV (PLWHA). The methodology is cross-sectional and the sample population includes 163 individuals (54% males, 46% females) who were randomly selected from the counseling centers for behavioral disorders of Medical Sciences of Tehran University. The average age of the sample was 37.48 ± 10.29 years old and the main cause of HIV infection was the sexual intercourse with spouse/non-spouse. The results of this study indicate that there is a significant and inverse relationship between general social stigma with the duration of HIV infection (r = -0.31, P < .05). There is also a positive and significant relationship between the general family social support and its subscales (information support, seeking support, instrumental support) with the duration of the infectious disease (r = +0.20, P < .05), which means that with increasing duration of the disease, the level of family social support increases. The general social stigma score with the general family social support showed a significant correlation (inverse) (r = -0.43, P < .05). It seems that the design and implementation of appropriate psychosocial interventions to increase family social support and reduce social stigma associated with HIV/AIDS are important in Iranian society and societies that are family-oriented and the family institution continues its protective and supportive functions.

Celiac disease in type 1 diabetes mellitus in the Kingdom of Saudi Arabia. Characterization and meta-analysis.

OBJECTIVES: To characterize and meta-analyze the pertinent studies concerning celiac disease (CD) among patients with type 1 diabetes mellitus (T1DM) in the Kingdom of Saudi Arabia. Methods: Data (from the relevant articles) were analyzed using both the Statistical Package for Social Sciences, version 20 (IBM Corp., Armonk, NY, USA) program and the comprehensive meta-analysis (CMA) program. This study was conducted between March and July 2018 at King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia. Written ethical approval was not obtained because this study was a retrospective literature review and analysis. Results: The prevalence of seropositive-CD was 15.88% with high heterogeneity (I2=84.0), while the prevalence of biopsy-proven CD was 12% with high heterogeneity (I2=82.7). Anti-transglutaminase was used in 7 of the 8 studies; alone in 4; with endomysial antibodies in 2; and with antigliadin antibodies (AGA) in one. In the remaining study, antireticulin antibodies was used with AGA. The age of the involved patients ranged from 8 months to 50 years old. Conclusion: The prevalence of biopsy-proven CD among T1DM patients in Kingdom of Saudi Arabia (12.0%) was double the global prevalence (6.0%), and much higher than the normal Saudi population (1.4%). The female-to-male ratio (2:1) of CD patients in T1DM was the same as in the normal population in Kingdom of Saudi Arabia. No significant difference was detected between the reported serologically-proven rates and the reported biopsy-proven rates (p=0.093).

Celiac disease among at-risk individuals in Saudi Arabia.

OBJECTIVES: To perform a meta-analysis for celiac diseases (CD) among at-risk populations in Kingdom of Saudi Arabia (KSA), as well as a comparison with our previously reported meta-analysis in the normal population. METHODS: In March 2018, at King Abdulaziz University,  Jeddah, KSA we commenced a retrospective comprehensive database and journal search for CD among at-risk populations in SA. Data from each of the relevant articles were analyzed using the  Statistical Package for Social Science Version 20 (Armonk, NY: IBM Corp.). and the comprehensive meta-analysis program (CMA). The collected data were part of a retrospective literature review and analysis. Thus, a written ethical approval was not obtained before commencing the study. Results: Sixteen articles were found covering type-1 diabetes mellitus (DM), short stature (SS), and down syndrome (DS). Ages 1-50 years . The prevalence of seropositive-CD was 15.6% with high heterogeneity (I2=80.353), while prevalence of biopsy-proven CD was 10.6% with high heterogeneity (I2=73.359). Another article reported the CD prevalence in the at-risk population as 18.4% for the seroprevalence and  6.9% for the biopsy-proven CD. Anti-transglutaminase (anti-tTG) was used in 12 studies; in the remaining 4 studies (EMA in 2, ARA with AGA in one and no details given in one study). Conclusion: Both the prevalence of biopsy-proven CD (10.6%) and seroprevalence (15.6%) were higher than those we previously reported in the normal population (1.4% and 2.7%). The female-to-male ratio (1.9/1) of CD patients was the same in normal and at-risk populations in SA. Meta-analysis for prevalence of CD in DM, SS, and DS separately in SA is recommended.

Hepatitis C: an Overview of Various Laboratory Assays with their Mode of Diagnostic Cooperation.

BACKGROUND: This review describes in chronological order the different assays for hepatitis C virus (HCV) antibodies, for the core antigen and for the HCV-RNA. METHODS: By ascending chronological order, the enzyme-linked immunosorbent assay (ELISA), rapid diagnostic tests (RDTs), HCV-Ab IgG avidity index (HCV AI), and Cy3-labeled microarray assay have been described for HCV antibodies in addition to ELISA for the total HCV core antigen (Ag). RESULTS: The recombinant immunoblot assay (RIBA) is a confirmatory test for HCV-Ab in blood, which is no longer needed due to the use of the sensitive third and fourth generation ELISA in addition to HCV-RNA detection by the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). ELISA and RIBA measure current and prior exposure to HCV infection, but cannot discriminate between the two. RT-PCR is performed after ELISA for the diagnosis of HCV infection whether acute, chronic, false positive or false negative ELISA. CONCLUSIONS: The cooperation between ELISA and RT-PCR in the diagnosis of HCV infection has been tabulated and discussed. HCV genotyping and subtyping testing is essential in pre-treatment evaluation of the patients for setting valuable treatment strategies and in understanding the epidemiology of the virus.

The Role of Sexual Behaviors in the Relapse Process in Iranian Methamphetamine Users: A Qualitative Study.

BACKGROUND: The awareness of sexual experiences could be an effective factor in preventing high-risk sexual behavior pertaining to relapse during the recovery period of substances. This research explored the role of sexual behaviors among Iranian methamphetamine (MA) users in relapse process. METHODS: The study was conducted with a qualitative approach using content analysis method. 28 participants were selected through purposeful and theoretical sampling. Data were collected based on face-to-face, in-depth, semi-structured interviews based on open-ended questions. Interviews continued until the data saturation had occurred. All interviews were examined in four stages of codes, sub-categories, categories and themes according to the content analysis of explanations and descriptions of sexual behaviors. FINDINGS: Two main themes were emerged from the analysis of interviews, including extreme pleasure seeking (including the main categories of sexual tunnel vision and sexual totalitarianism) and comprehended threat (including the main categories of internal conflict and external disorganization) as well as 10 subcategories. CONCLUSION: The results indicated that sexual behaviors played an important role in relapse process among Iranian MA users and needed to be considered and managed properly in the planning of prevention, treatment, and rehabilitation.

Anti-mutated citrullinated vimentin antibody and rheumatoid factor (prevalence and association) in rheumatoid arthritis patients; Saudi and non-Saudi.

UNLABELLED: background: The aims of this study were to assess the prevalence of anti-mutated citrullinated vimentin (MCV) antibodies and rheumatoid factor (RF) and to evaluate their association in rheumatoid arthritis patients, both Saudi and non-Saudi. METHODS: Retrospectively, we studied 280 rheumatoid arthritis patients, at King Abdulaziz University Hospital. The antibodies were measured by enzyme linked immunosorbent assay and rheumatoid factor by nephelometry. RESULTS: The 280 patients included 196 Saudis and 84 non-Saudis, 88% females and 12% males, and the mean age was 45.3 years (SD = 14.3). Prevalence of rheumatoid factor was 141/280 (50%) divided as 93/196 (47.5%) Saudis and 48/84 (57%) non-Saudis, with no significant differences (p > 0.05). Prevalence of mutated citrullinated vimentin antibodies was 165/280 (58.2%) divided as 121/196 (61.7%) Saudis and 44/84 (52.4%) non-Saudis, with no significant differences (p > 0.05). Among RF -ve patients, considerable numbers were anti-MCV +ve, and vice versa. Also, among the anti-MCV -ve patients, considerable numbers were RF +ve, and vice versa. In all cohorts and in Saudi and non Saudi patients, anti-MCV positivity was significantly associated with RF positivity (odds ratio (OR) 3.15; 95% CI 1.9, 5.19/p = 0.000); ESR and CRP were high with significant correlation (p < 0.005) with each other, with RF positivity but not with anti-MC positivity. Anti-MC positivity showed no significant correlation with age and gender. CONCLUSIONS: In this cohort of patients, anti-MCV antibodies are a useful diagnostic tool for RA, but its combination with RF is essential. Both markers are significantly associated. Larger scale studies are recommended. Correlation of anti-MCV with treatment and with disease activity still has to be published.

Pattern of drugs use and association with anti-mutated citrullinated vimentin antibody in rheumatoid arthritis.

OBJECTIVES: To demonstrate the pattern of disease-modifying antirheumatic drugs (DMARDs) use in Saudi and non-Saudi rheumatoid arthritis (RA) patients, and to evaluate the association of DMARDs use with anti-mutated citrullinated vimentin (anti-MCV) positivity and other factors. METHODS: Retrospectively, for a period of 7 years (2007-2014), we studied 205 RA patients, at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia. All patients used DMARDs. Pattern of use for all 6 DMARDs was almost the same among Saudis and non-Saudis with no significant difference (p>0.05) for each DMARD; MTX was the most commonly used DMARD (71-76%). RESULTS: There was no association between anti-MCV positivity and different DMARDs use. Methotrexate was used 76 times as combination, scoring the highest in this respect. There was a significant correlation (p<0.05) between Plaquenil with Methotrexate and with Sulfasalazine; Leflunomide with anti-TNF and with Prednisolone; age with Methotrexate and with Plaquenil; anti-MCV positivity with Prednisolone. Saudi/non-Saudi status showed no correlation with all factors or drugs. There was no significant association between DMARDs and comorbidity. CONCLUSION: Similar to worldwide results, MTX was the most commonly used DMARD; with the addition of anti-TNF to increase the effect, and folic acid to minimize the side effects. In this cohort, the pattern of use for all DMARDs was similar among Saudis and non-Saudis; treatment depended neither on anti-MCV positivity nor on the presence of comorbid conditions. A study of the association of DMARDs with disease activity is recommended.

Incompatible blood transfusion: Challenging yet lifesaving in the management of acute severe autoimmune hemolytic anemia.

BACKGROUND AND AIM: Autoimmune hemolytic anemia (AIHA) is characterized by the production of autoantibodies directed against red cell antigens. Most patients of AIHA arrive in the emergency or out-patient department (OPD) with severe anemia requiring urgent blood transfusion. Here we share our experience of managing these patients with incompatible blood transfusions and suggest the minimal test required to assure patient safety. MATERIALS AND METHODS: A total of 14 patients admitted with severe anemia, diagnosed with AIHA and requiring blood transfusion urgently were included in the study. A series of immunohematological investigations were performed to confirm the diagnosis and issue best match packed red blood cells (PRBC) to these patients. RESULTS: A total of 167 PRBC units were crossmatched for 14 patients of which 46 units (28%) were found to be best match ones and 26 (56.5%) of these units were transfused. A mean turn around time of 222 min was observed in issuing the "best match" blood. Severe hemolysis was observed in all patients with a median hemoglobin increment of 0.88 g/dl after each unit PRBC transfusion. CONCLUSION: Decision to transfuse in AIHA should be based on the clinical condition of the patient. No critical patient should be denied blood transfusion due to serological incompatibility. Minimum investigations such as direct antiglobulin test (DAT), antibody screening and autocontrol should be performed to ensure transfusion safety in patients. All transfusion services should be capable of issuing "best match" PRBCs in AIHA.

Dynamics analysis of a multi-strain cholera model with an imperfect vaccine.

A new two-strain model, for assessing the impact of basic control measures, treatment and dose-structured mass vaccination on cholera transmission dynamics in a population, is designed. The model has a globally-asymptotically stable disease-free equilibrium whenever its associated reproduction number is less than unity. The model has a unique, and locally-asymptotically stable, endemic equilibrium when the threshold quantity exceeds unity and another condition holds. Numerical simulations of the model show that, with the expected 50% minimum efficacy of the first vaccine dose, vaccinating 55% of the susceptible population with the first vaccine dose will be sufficient to effectively control the spread of cholera in the community. Such effective control can also be achieved if 50% of the first vaccine dose recipients take the second dose. It is shown that a control strategy that emphasizes the use of antibiotic treatment is more effective than one that emphasizes the use of basic (non-pharmaceutical) anti-cholera control measures only. Numerical simulations show that, while the universal strategy (involving all three control measures) gives the best outcome in minimizing cholera burden in the community, the combined basic anti-cholera control measures and treatment strategy also has very effective community-wide impact.

Dynamics of a model with quarantine-adjusted incidence and quarantine of susceptible individuals.

A new deterministic model for the spread of a communicable disease that is controllable using mass quarantine is designed. Unlike in the case of the vast majority of prior quarantine models in the literature, the new model includes a quarantine-adjusted incidence function for the infection rate and the quarantine of susceptible individuals suspected of being exposed to the disease (thereby making it more realistic epidemiologically). The earlier quarantine models tend to only explicitly consider individuals who are already infected, but show no clinical symptoms of the disease (i.e., those latently-infected), in the quarantine class (while ignoring the quarantine of susceptible individuals). In reality, however, the vast majority of people in quarantine (during a disease outbreak) are susceptible. Rigorous analysis of the model shows that the assumed imperfect nature of quarantine (in preventing the infection of quarantined susceptible individuals) induces the phenomenon of backward bifurcation when the associated reproduction threshold is less than unity (thereby making effective disease control difficult). For the case when the efficacy of quarantine to prevent infection during quarantine is perfect, the disease-free equilibrium is globally-asymptotically stable when the reproduction threshold is less than unity. Furthermore, the model has a unique endemic equilibrium when the reproduction threshold exceeds unity (and the disease persists in the population in this case).

Global stability analysis of SEIR model with holling type II incidence function.

A deterministic model for the transmission dynamics of a communicable disease is developed and rigorously analysed. The model, consisting of five mutually exclusive compartments representing the human dynamics, has a globally asymptotically stable disease-free equilibrium (DFE) whenever a certain epidemiological threshold, known as the basic reproduction number (ℛ0), is less than unity; in such a case the endemic equilibrium does not exist. On the other hand, when the reproduction number is greater than unity, it is shown, using nonlinear Lyapunov function of Goh-Volterra type, in conjunction with the LaSalle's invariance principle, that the unique endemic equilibrium of the model is globally asymptotically stable under certain conditions. Furthermore, the disease is shown to be uniformly persistent whenever ℛ0 > 1.

Threshold dynamics of a non-autonomous SEIRS model with quarantine and isolation.

A model for assessing the effect of periodic fluctuations on the transmission dynamics of a communicable disease, subject to quarantine (of asymptomatic cases) and isolation (of individuals with clinical symptoms of the disease), is considered. The model, which is of a form of a non-autonomous system of non-linear differential equations, is analysed qualitatively and numerically. It is shown that the disease-free solution is globally-asymptotically stable whenever the associated basic reproduction ratio of the model is less than unity, and the disease persists in the population when the reproduction ratio exceeds unity. This study shows that adding periodicity to the autonomous quarantine/isolation model developed in Safi and Gumel (Discret Contin Dyn Syst Ser B 14:209-231, 2010) does not alter the threshold dynamics of the autonomous system with respect to the elimination or persistence of the disease in the population.