Incidence and risk factors of SARS-CoV-2 infection among workers in a public health laboratory in Tunisia.

The aim of this study was to measure the extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among workers at the Institut Pasteur de Tunis (IPT), a public health laboratory involved in the management of the COVID-19 pandemic in Tunisia, and to identify risk factors for infection in this occupational setting. A cross-sectional survey was conducted on IPT workers not vaccinated against coronavirus disease 2019 (COVID-19). Participants completed a questionnaire that included a history of reverse transcription-polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection. Immunoglobulin G antibodies against the receptor-binding domain of the spike antigen (anti-S-RBD IgG) and the nucleocapsid protein (anti-N IgG) of the SARS-CoV-2 virus were detected by enzyme-linked immunoassay (ELISA). A multivariate analysis was used to identify factors significantly associated with SARS-CoV-2 infection. A total of 428 workers were enrolled in the study. The prevalence of anti-S-RBD and/or anti-N IgG antibodies was 32.9% [28.7-37.4]. The cumulative incidence of SARS-CoV-2 infection (positive serology and/or previous positive RT-PCR test) was 40.0% [35.5-44.9], while the proportion with asymptomatic infection was 32.9%. One-third of the participants with RT-PCR-confirmed infection tested seronegative more than 90 days postinfection. Participants aged over 40 and laborers were more susceptible to infection (adjusted OR [AOR] = 1.65 [1.08-2.51] and AOR = 2.67 [1.45-4.89], respectively), while tobacco smokers had a lower risk of infection (AOR = 0.54 [0.29-0.97]). The SARS-CoV-2 infection rate among IPT workers was not significantly different from that detected concurrently in the general population. Hence, the professional activities conducted in this public health laboratory did not generate additional risk to that incurred outside the institute in day-to-day activities.

First Report of Two Jaculus Rodents as Potential Reservoir Hosts of Leishmania Parasites in Tunisia.

This study shows, for the first time, natural Leishmania infection among Jaculus spp. in an endemic region of Tataouine, South Tunisia. To better characterize the transmission cycles in this complex focus of mixed transmission, Leishmania detection and species identification were performed by direct examination, internal transcribed spacer-1 (ITS1)-PCR-restriction fragment length polymorphism (RFLP), and sequencing of Jaculus (J.) jaculus (Linnaeus, 1758) and J. hirtipes (Lichtenstein, 1823) rodent species, which are frequently encountered in this area. Leishmania parasites were observed in 19 (41.3%) smears, while DNA parasites were detected in 28 (60.9%) Jaculus spp. spleens; among them, 12 (54.5%) were from 22 J. jaculus individuals and 16 (66.7%) were from 24 J. hirtipes individuals. Leishmania parasites were confirmed as Leishmania (L.) killicki (syn. L. tropica) in two J. hirtipes individuals (4.3%) and L. major (n = 24; 52.2%) in 10 J. jaculus and 14 J. hirtipes individuals. This finding represents the first evidence of natural infection with Leishmania parasites in rodents belonging to the Jaculus genus, providing the rationale to consider them as potential reservoir hosts of Old World Leishmania parasites in Tunisia and North Africa.

COVID-19 in Tunisia (North Africa): Seroprevalence of SARS-CoV-2 in the General Population of the Capital City Tunis.

Seroprevalence studies are essential to get an accurate estimate of the actual SARS-CoV-2 diffusion within populations. We report on the findings of the first serosurvey conducted in Tunis prior to the implementation of mass vaccination and analyzed factors associated with seropositivity. A household cross sectional survey was conducted (March-April 2021) in Tunis, spanning the end of the second wave and the beginning of the third wave of COVID-19. SARS-CoV-2 specific immunoglobulin G (IgG) antibodies to the spike (S-RBD) or the nucleocapsid (N) proteins were detected by in-house ELISA tests. The survey included 1676 individuals from 431 households. The mean age and sex ratio were 43.3 ± 20.9 years and 0.6, respectively. The weighted seroprevalence of anti-N and/or anti-S-RBD IgG antibodies was equal to 38.0% (34.6-41.5). In multivariate analysis, age under 10, no tobacco use, previous diagnosis of COVID-19, a history of COVID-19 related symptoms and contact with a COVID-19 case within the household, were independently associated with higher SARS-CoV-2 seroprevalence. More than one third of people living in Tunis obtained antibodies to SARS-CoV-2. Further studies are needed to monitor changes in these figures as Tunisian population is confronted to the subsequent epidemic waves and to guide the vaccine strategy.

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.

Insight into the global evolution of Rodentia associated Morbilli-related paramyxoviruses.

One portion of the family Paramyxoviridae is a group of Unclassified Morbilli-Related Viruses (UMRV) recently recognized in wild small mammals. At a global level, the evolutionary history of these viruses is not properly understood and the relationships between UMRV and their hosts still remain largely unstudied. The present study revealed, for the first time, that Rodentia associated UMRV emerged from a common ancestor in southern Africa more than 4000 years ago. Sequenced UMRV originating from different regions in the world, clustered into four well-supported viral lineages, which suggest that strain diversification occurred during host dispersal and associated exchanges, with purifying selection pressure as the principal evolutionary force. In addition, multi-introductions on different continents and islands of Rodentia associated UMRV and spillover between rodent species, most probably Rattus rattus, were detected and indicate that these animals are implicated in the vectoring and in the worldwide emergence of this virus group. The natural history and the evolution dynamics of these zoonotic viruses, originating from and hosted by wild animals, are most likely shaped by commensalism related to human activities.

Leishmania major infection among Psammomys obesus and Meriones shawi: reservoirs of zoonotic cutaneous leishmaniasis in Sidi Bouzid(central Tunisia).

A study was undertaken between November 2008 and March 2010, in the focus of cutaneous leishmaniasis of Central Tunisia, to evaluate the role of Psammomys obesus (n=472) and Meriones shawi (n=167) as reservoir hosts for Leishmania major infection. Prevalence of L. major infection was 7% versus 5% for culture (p=not signifiant [NS]), 19% versus 16% for direct examination of smears (p=NS), and 20% versus 33% (p=NS) for Indirect Fluorescent Antibody Test among P. obesus and M. shawi, respectively. The peak of this infection was in winter and autumn and increased steadily with age for the both species of rodents. The clinical examination showed that depilation, hyper-pigmentation, ignition, and severe edema of the higher edge of the ears were the most frequent signs observed in the study sample (all signs combined: 47% for P. obesus versus 43% for M. shawi; p=NS). However, the lesions were bilateral and seem to be more destructive among M. shawi compared with P. obesus. Asymptomatic infection was ~40% for both rodents. This study demonstrated that M. shawi plays an important role in the transmission and the emergence of Leishmania major cutaneous leishmaniasis in Tunisia.

First report of natural infection of least weasel (Mustela nivalis Linnaeus, 1776) with Leishmania major in Tunisia.

Zoonotic cutaneous leishmaniasis, caused by Leishmania major (L. major), is endemic in Tunisia. Several rodents have been identified as reservoir hosts of parasites. This study reports, for the first time, the natural infection with L. major zymodeme MON-25 in a specimen of least weasel: Mustela nivalis Linnaeus, 1776 (M. nivalis) collected in Sidi Bouzid. This finding justifies further research on larger samples of this animal to verify its role as a potential reservoir host for cutaneous leishmaniasis in Tunisia.

Immunogenicity and efficacy of an in-house developed cell-culture derived veterinarian rabies vaccine.

The efficiency of an inactivated tissue culture rabies vaccine produced on BHK-21 cells, according to an in-house developed process, was evaluated and compared to a commercial cell-tissue culture vaccine (Rabisin). Fifteen experimental dogs from local common breed were duly conditioned during a quarantine period, then vaccinated via the subcutaneous route with 1 ml of either the tissue culture vaccine developed in-house or the commercial vaccine Rabisin. The immune response of each dog was monitored for 162 days. Serum-neutralizing antibodies titers to rabies virus were determined by the rapid fluorescent focus inhibition test (RFFIT) which confirmed the strong response of dogs to both vaccines except one dog in the Rabisin group. The dogs were then challenged in the masseter muscle with a rabies street virus of canine origin. All vaccinated dogs except the single dog in the Rabisin group that failed to respond to the vaccine, survived the challenge. In contrast, 80% of animals in the control non-vaccinated group, developed rabies and died. A field vaccine trial was also conducted: 1,000 local dogs living in field conditions received one subcutaneous dose of the locally developed vaccine. Serum neutralizing antibody titers to rabies virus was determined by RFFIT at days 0, 60 and 360. Mean rabies neutralizing antibody titers were equal to 0.786, 3.73 and 1.55 IU/ml, respectively. The percentage of dogs with a neutralizing rabies antibody titer higher than the 0.5 IU/ml mandated WHO threshold, was 30%, 91.4% and 87.5% at day 0, 2 months and 1 year post-vaccination, respectively. These data demonstrate the efficiency of the in-house developed vaccine produced on BHK-21 cells in both experimental and field conditions and support its use in dog mass vaccination campaigns.