Observational study of vaccine effectiveness 20 years after the introduction of universal hepatitis B vaccination in Tunisia.

OBJECTIVES: The objectives of this study were to estimate the national prevalence of hepatitis B infection in Tunisia using data from a nationwide survey, to compare results with those obtained in 1996 survey and to evaluate the impact of vaccination twenty years after its introduction. METHODS: A National household-based cross sectional and serological survey was undertaken in 2015 from randomly selected districts using two-stage sampling. Data collection was performed using standardized and pretested questionnaires and collected blood samples were tested for markers of hepatitis B virus infection. RESULTS: National point prevalence of Hepatitis B surface antigen was 1.7% (95% CI [1.6-1.9%]). The highest prevalence was found in the Center and South regions with respectively 2.3% (95% CI [2.0-2.7%]) and 2.2% (95% CI [1.8-2.8%]). Vaccine effectiveness (VE) was 88.6% (95% CI [81.5-93.0%]) and was higher among population aged less than 20 years 96.1% (95% CI [70.1-99.5%]) than those aged more than 20 years 59.0% (95% CI [32.0-75.3%]). VE was 85.6% (95% CI [65.8-93.9%]) is hyper-endemic areas and 89.1% (95% CI [80.3-94.0%]) in meso-endemic and hypo-endemic areas. CONCLUSIONS: The prevalence of Hepatitis B surface antigen decreased compared to previous estimations and classify Tunisia as a low endemic country as result to the introduction of vaccination since 1995.

Determination of arylsulfatase A pseudodeficiency allele and haplotype frequency in the Tunisian population.

Arylsulfatase A (ASA) is a lysosomal enzyme involved in the catabolism of cerebroside sulfate. ASA deficiency is associated with metachromatic leukodystrophy (MLD). Low ASA activities have also been reported in a more common condition with no apparent clinical consequences termed ASA pseudo-deficiency (ASA-PD) which is associated with two linked mutations in the ASA gene (c.1049A>G and c.*96A>G). This study aimed to investigate the frequency of the two ASA-PD variants and their linkage disequilibrium (LD) among Tunisians. ASA-PD variants were detected in 129 healthy Tunisians and their frequencies were compared to those described worldwide. The frequency of the PD allele was estimated at 17.4% for the overall sample, with c.1049A>G and c.*96A>G frequencies of 25.6 and 17.4%, respectively. This study also revealed a high LD between the two ASA-PD variants (r(2) = 0.61). Inter-population analysis revealed similarities in the ASA-PD genetic structure between Tunisians and populations from Middle East with c.*96A>G frequencies being the highest in the world. A significant North vs. South genetic differentiation in the ASA-PD frequency was also observed in Tunisian population who seems genetically intermediate between Africans, Middle-Easterners and Europeans. This is the first report on the allele frequency of the ASA-PD in North Africa, revealing a relatively high frequency of the PD allele among Tunisians. This study gives also evidence on the importance of discriminating ASA-PD allele from pathological mutations causing MLD and supporting enzymatic activity testing with both sulfatiduria determination and genetic testing in the differential diagnosis of MLD in the Tunisian population.

Larval habitats characterization and species composition of Anopheles mosquitoes in Tunisia, with particular attention to Anopheles maculipennis complex.

In Tunisia, malaria transmission has been interrupted since 1980. However, the growing number of imported cases and the persistence of putative vectors stress the need for additional studies to assess the risk of malaria resurgence in the country. In this context, our aim was to update entomological data concerning Anopheles mosquitoes in Tunisia. From May to October of 2012, mosquito larval specimens were captured in 60 breeding sites throughout the country and identified at the species level using morphological keys. Environmental parameters of the larval habitats were recorded. Specimens belonging to the An. maculipennis complex were further identified to sibling species by the ribosomal deoxyribonucleic acid (rDNA)-internal transcribed spacer 2 (ITS2) polymerase chain reaction (PCR) technique. In total, 647 Anopheles larvae were collected from 25 habitats. Four species, including An. labranchiae, An. multicolor, An. sergentii, and An. algeriensis, were morphologically identified. rDNA-ITS2 PCR confirmed that An. labranchiae is the sole member of the An. maculipennis complex in Tunisia. An. labranchiae was collected throughout northern and central Tunisia, and it was highly associated with rural habitat, clear water, and sunlight areas. Larvae of An. multicolor and An. sergentii existed separately or together and were collected in southern Tunisia in similar types of breeding places.

Hepatitis E virus seroprevalence among hemodialysis and hemophiliac patients in Tunisia (North Africa).

The aims of this study are to determine seroprevalence of Hepatitis E virus (HEV) in Tunisian blood donors and to evaluate its risk of parenteral transmission. Sera collected from 426 blood donors were tested for HEV IgG by indirect ELISA. Individuals were recruited from two national transfusion centers, in the North and the South of the country. Seroprevalence of HEV IgG was then compared with two other groups with increased risk of exposure to parenterally transmitted agents: 80 hemophiliac and 286 hemodialysis patients. Among blood donors, the seroprevalence was estimated to be 4.5%. It was significantly higher in the hemophiliac and hemodialysis groups with 7.5% and 10.2%, respectively, (P = 0.002). No significant correlation was observed for this IgG 1 seroprevalence between age and sex among three studied groups. These results suggest that HEV has a high risk of parenteral transmission and confirm that the low endemicity of hepatitis E in Tunisia was observed.

Diagnosis of mediterranean visceral leishmaniasis by detection of leishmania antibodies and leishmania DNA in oral fluid samples collected using an Oracol device.

Current methods for diagnosis of visceral leishmaniasis (VL) require invasive sampling procedures such as visceral aspiration and/or blood drawing. The use of diagnostic tests using oral fluid, which is easier to collect, would be more simple and practical for VL diagnosis, especially under field conditions. Oral fluids from 37 VL patients and 40 healthy controls were collected using Oracol devices. Blood samples and oral fluid specimens from both groups were analyzed by recombinant protein K39 (rK39) enzyme-linked immunosorbent assay and quantitative real-time PCR. Detection of antibodies in the oral fluid had a sensitivity of 100% and a specificity of 97.5%. Antibody levels measured in serum and oral fluid showed a significant positive correlation (ρ = 0.655 and P = 0.01). Detection of Leishmania DNA in oral fluid had a sensitivity of 94.6% and a specificity of 90%. The median parasite load estimated in blood was 133 parasites/ml (interquartile range [IR], 10 to 1,048), whereas that in oral fluid specimens was 3 parasites/ml (IR, 0.41 to 92). However, there was no significant linear relationship between parasite loads assessed in the two biological samples (ρ = 0.31 and P = 0.06). VL diagnosis based on specific antibody detection and Leishmania DNA identification using oral fluid samples was equivalent in accuracy to that using blood and therefore is promising for clinical use.

Epidemiologic and clinical features of cutaneous leishmaniasis in southeastern Tunisia.

Species-specific diagnosis was performed in 66 patients with cutaneous leishmaniasis (CL) living in Tataouine focus in southeastern Tunisia. Leishmania DNA was extracted directly from dermal scrapings (n = 66) and from parasites obtained in culture (n = 12). Species were identified by using polymerase chain reaction-restriction fragment length polymorphism analysis for internal transcribed spacer region 1 and isoenzyme analysis. Leishmania tropica and L. major were identified in 31 (47%) and 35 (53%) cases respectively. Leishmania tropica CL cases were geographically scattered, and L. major CL cases were clustered. Lesions caused by L. tropica were mostly single (83.8%) and face-localized (55.8%), and lesions caused by L. major were multiple (57.1%; P < 0.001) and situated on limbs (83.7%; P < 0.001). For both species, most lesion onsets were reported during June-January. However, lesions that emerged during February-May were mainly caused by L. tropica (83.3%; P < 0.01). Moreover, the delay before seeking medical advice was higher for L. tropica infections than for L. major infections (P < 0.05).

Heterogeneity of hepatitis B transmission in Tunisia: risk factors for infection and chronic carriage before the introduction of a universal vaccine program.

UNLABELLED: A population-based sero-epidemiological study enrolled 9486 volunteers in two governorates, Béja in the north and Tataouine in the south of Tunisia, in order to assess the magnitude of HBV transmission heterogeneity between the north and the south and within the same governorate, as well as the risk factors associated with infection and chronic carriage. RESULTS: The overall prevalence of anti-HBc, HBsAg and chronic carriage was 28.5, 5.3 and 2.9%, respectively. Significant differences were observed between the two governorates according to anti-HBc (32.1% in Béja and 27.8% in Tataouine; p=0.005) and HBsAg prevalence (4.2% in Béja and 5.6% in Tataouine; p=0.001). Significant differences were noticed between districts revealing important heterogeneity in HBV transmission within the same governorate (HBsAg ranged from 12 to <2% within the same governorate). At the individual level, the presence of a family member infected with HBV, scarification practices, needle practices in the Primary Care Center and gender (male) significantly increased the risk of anti-Hbc, HBsAg positivity and chronic carriage of infection while existence of sanitation in the house was found to be protective. The basic reproductive number and the force of infection confirmed the heterogeneity of transmission. Horizontal transmission within the family explains hyperendemic clusters in Tunisia.