Applying the moving epidemic method to determine influenza epidemic and intensity thresholds using influenza-like illness surveillance data 2009-2018 in Tunisia.

BACKGROUND: Defining the start and assessing the intensity of influenza seasons are essential to ensure timely preventive and control measures and to contribute to the pandemic preparedness. The present study aimed to determine the epidemic and intensity thresholds of influenza season in Tunisia using the moving epidemic method. METHODS: We applied the moving epidemic method (MEM) using the R Language implementation (package "mem"). We have calculated the epidemic and the different intensity thresholds from historical data of the past nine influenza seasons (2009-2010 to 2017-2018) and assessed the impact of the 2009-2010 pandemic year. Data used were the weekly influenza-like illness (ILI) proportions compared with all outpatient acute consultations. The goodness of the model was assessed using a cross validation procedure. RESULTS: The average duration of influenza epidemic during a typical season was 20 weeks and ranged from 11 weeks (2009-2010 season) to 23 weeks (2015-2016 season). The epidemic threshold with the exclusion of the pandemic season was 6.25%. It had a very high sensitivity of 85% and a high specificity of 69%. The different levels of intensity were established as follows: low, if ILI proportion is below 9.74%, medium below 12.05%; high below 13.27%; and very high above this last rate. CONCLUSIONS: This is the first mathematically based study of seasonal threshold of influenza in Tunisia. As in other studies in different countries, the model has shown both good specificity and sensitivity, which allows timely and accurate detection of the start of influenza seasons. The findings will contribute to the development of more efficient measures for influenza prevention and control.

Evaluation of the influenza-like illness surveillance system in Tunisia, 2012-2015.

BACKGROUND: This study was initiated to evaluate, for the first time, the performance and quality of the influenza-like illness (ILI) surveillance system in Tunisia. METHODS: The evaluation covered the period of 2012-2015 and used different data sources to measure indicators related to data quality and completeness, representativeness, timeliness, simplicity, acceptability, flexibility, stability and utility. RESULTS: During the evaluation period, 485.221 ILI cases were reported among 6.386.621 outpatients at 268 ILI sentinel sites. To conserve resources, cases were only enrolled and tested for influenza during times when the number of patients meeting the ILI case definition exceeded 7% (10% after 2014) of the total number of outpatients for the week. When this benchmark was met, five to 10 patients were enrolled and sampled by nasopharyngeal swabs the following week. In total, The National Influenza Center (NIC) received 2476 samples, of which 683 (27.6%) were positive for influenza. The greatest strength of the system was its representativeness and flexibility. The timeliness of the data and the acceptability of the surveillance system performed moderately well; however, the utility of the data and the stability and simplicity of the surveillance system need improvement. Overall, the performance of the Tunisian influenza surveillance system was evaluated as performing moderately well for situational awareness in the country and for collecting representative influenza virologic samples. CONCLUSIONS: The influenza surveillance system in Tunisia provided pertinent evidence for public health interventions related to influenza situational awareness. To better monitor influenza, we propose that ILI surveillance should be limited to sites that are currently performing well and the quality of data collected should be closely monitored and improved.

Time of onset, viral load, relapse, and duration of active cytomegalovirus infection in bone marrow transplant outcomes.

OBJECTIVES: Active cytomegalovirus infection remains a major problem for bone marrow transplant recipients. If not quickly diagnosed and treated, it can evolve into cytomegalovirus disease, which represents a life-threatening complication. In this work, we sought to evaluate the interactions between clinical complications after bone marrow transplant and factors associated with active cytomegalovirus infection. MATERIALS AND METHODS: We evaluated 91 allogeneic bone marrow transplant recipients (35 female, 56 male; median age, 20 years; age range, 3-47 years) for malignant and nonmalignant hematologic diseases. Active cytomegalovirus infection was monitored using pp65 cytomegalovirus antigenemia and a semiquantitative cytomegalovirus polymerase chain reaction. Cytomegalovirus end-organ disease was defined as an association between compatible signs and symptoms (dyspnea, hypoxia, and diarrhea) and detection of cytomegalovirus (>or= 2,000 cytomegalovirus genome copies/mL) by hybrid capture assay in tissue biopsy. Variables were compared using the chi-square and Fisher exact tests. Time of death after bone marrow transplant was plotted using the Kaplan-Meier method. A Cox regression model was used for multivariate survival analysis with 95% confidence limits. RESULTS: Sixty-four patients experienced active cytomegalovirus infection, 26 had acute graft-versus-host disease, and 11 had cytomegalovirus diseases. The overall survival rate at 4 years was 83.52%. On multivariate analyses, cytomegalovirus disease (hazard ratio = 15.9, P = .001) and age older than 18 years (hazard ratio = 8, P = .18) were the only independent negative prognostic factors for overall survival. Occurrence of acute graft-versus-host disease was increased by early active cytomegalovirus infection (P = .03) and represents a significant factor for active cytomegalovirus infection recurrence (P = .01). Viral load as quantified by antigenemia and cytomegalovirus DNA in the patients' peripheral blood leukocytes was significantly associated with clinical complications. CONCLUSIONS: Active cytomegalovirus infection interacts significantly in several ways with graft-versus-host disease and others infections. Acute graft-versus-host disease increases the chances of a poor outcome, especially of acquiring cytomegalovirus disease. Cytomegalovirus disease constitutes a significant independent risk factor for death after bone marrow transplant.

Effects on immunological and virological outcome of patients using one protease inhibitor or one non-nucleoside reverse transcriptase inhibitor in a triple antiretroviral therapy: normal clinical practice versus clinical trial findings.

We compared the response of two standard 3-drug regimens containing two-nucleoside reverse transcriptase inhibitor (Zidovudine +Lamivudine) plus either a protease inhibitor (PIs) (Indinavir) or a non-nucleoside reverse transcriptase inhibitor (NNRTIs) (Efavirenz) among treatment-naïve or treatment-experienced HIV-infected persons. The obtained results will be compared to clinical trial findings. Through a retrospective study, we compared the virological and immunological response of 119 Tunisian HIV-1 infected patients (North Africa) who started for the first time/ in salvage use a triple antiretroviral treatment containing one NNRTI (group A1/group A2) or one PI (group B1/group B2). Viral load (VL) was analysed with Amplicor HIV-1 Monitor test and drug resistance mutations were examined by using two distinct line probe assays (LiPA). The analysis according to the received treatment showed an average of 0.45 log(10) drop in the mean VL among groups A2 and B2. For naïve patients, 62.5% of group A1 reached an undetectable VL versus 53.5% for group B1 (p < 0.001). With regard to the CD4 cell count change, we observed a mean increase of more than 65% versus baseline within group A1 in comparison with 42% for group B1 (p < 0.001). Genotypic resistance assays showed that patients of group A2 had significantly more resistance mutations than those of group B2 (2.66 vs. 0.75 (p = 0.0039)). Finally, 15 patients who were failing were switched to indinavir or efavirenz. When indinavir was replaced by efavirenz, we observed an increase in the plasma VL. With regard to the effects on immunological and virological outcome of patients using PIs or NNRTIs in a triple antiretroviral therapy, our observations in normal clinical practice supported the reported clinical trial findings but are not in favour of replacing indinavir by efavirenz in failing regimen.