Chirped self-similar solitary waves for the generalized nonlinear Schrödinger equation with distributed two-power-law nonlinearities

We investigate the propagation characteristics of the chirped self-similar solitary waves in non-Kerr nonlinear media within the framework of the generalized nonlinear Schrödinger equation with distributed dispersion, two-power-law nonlinearities, and gain or loss. This model contains many special types of nonlinear equations that appear in various branches of contemporary physics. We extend the self-similar analysis presented for searching chirped self-similar structures of the cubic model to a more general problem involving two nonlinear terms of arbitrary power. A variety of exact linearly chirped localized solutions with interesting properties are derived in the presence of all physical effects. The solutions comprise bright, kink and antikink, and algebraic solitary wave solutions, illustrating the potentially rich set of self-similar pulses of the model. It is shown that these optical pulses possess a linear chirp that leads to efficient compression or amplification, and thus are particularly useful in the design of optical fiber amplifiers, optical pulse compressors, and solitary wave based communication links. Finally, the stability of the self-similar solutions is discussed numerically under finite initial perturbations.

An unusual case of gallbladder cancer

Pure squamous cell carcinoma (SCC) of gallbladder is a very rare tumour and is responsible for only 3% of the malignant neoplasm of this organ. We report a case of SCC of gallbladder in a 58-year-old woman. Through this new observation, we propose to study the clinicopathologic features, pathogeny and treatment of this rare entity.

[Indigenous malaria in Tunisia: 4 cases registered in 2013 in Tunisia]

BACKGROUND

Malaria has been eliminated in Tunisia since 1979, but the country remains, like all other countries harboring the vector, exposed to the potential risk of resurgence.

OBJECTIVES

Describe the clinical and epidemiological investigation of 4 cases of autochthonous malaria in July 2013 and report the main actions of regional and national response.

METHODS

Retrospective descriptive survey of the 4 clinical observations as well as the study of the regional report data of basic health care for the region of Tunis in 2013.

RESULTS

Febrile table concomitant for 4 Tunisian male patients, aged from 21 to 27 years old ; fortuitous discovery of Plasmodium falciparum when checking thrombocytopenia of patient 1 ; diagnosis in cascade of other cases following the epidemiological investigation and field consultation with clinicians ; 3 simple forms and a neuromalaria of favorable evolution ; negative entomological survey for anopheles ; elimination of imported malaria and blood-borne ; airport malaria highly probable. The response included the establishment of a regional and national monitoring unit, an information program aimed at health professionals concerned and public opinion, the involvement of health and entomology teams for the detection and census of potential larval habitats and the implementation of local mosquito eradication measures.

CONCLUSION

The clinical vigilance and competent biologist's eye is necessary to prevent the resurgence of this disease. The epidemiological surveillance system should be maintained and kept as well as the food safety standards monitoring at the borders.

Ileal pouch-anal anastomosis: Points of controversy

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the most commonly used procedure for elective treatment of patients with ulcerative colitis and familial adenomatous polyposis. Since its original description, the procedure has been modified in order to obtain optimal functional results with low morbidity and mortality, and yet provide a cure for the disease. In this review of the literature of restorative proctocolectomy with ileal pouch-anal anastomosis, we discuss these technical modifications, limiting our discussion to the current points of controversy. The current "hot topics" for debate are: indications for ileal pouch-anal or ileo-rectal anastomosis, indications for pouch surgery in the elderly, indeterminate colitis and Crohn's disease, the place of the laparoscopic approach, transanal mucosectomy with hand-sewn anastomosis vs. the double-stapled technique, the use of diverting ileostomy and the issue of the best route for delivery of pregnant women. Longer follow-up of patients and increased knowledge and experience with pouch surgery, coupled with ongoing prospective evaluation of the procedure are required to settle these issues.

Molecular Epidemiology of Measles Virus before and after the 2003 Mass Vaccination Campaign for Measles/Rubella in Iran

BACKGROUND

Molecular epidemiology of measles virus (MV) is important, not only to measure the success of measles vaccination programs but also to monitor the circulation and elimination of the virus worldwide. In this study, we compared MV obtained from patients before the 2003 mass vaccination MR campaign and viruses detected after 2003 until 2008 in Iran.

METHODS

The nucleoprotein (N) gene of 29 MV strains circulating in Iran between 2002 and 2008 were amplified by RT-PCR and subjected to sequence and phylogenetic analysis.

RESULTS

Molecular characterization of MV studied here revealed that although the outbreaks in Iran were associated with MV genotype D4, the isolated viruses clearly belonged to several different lineages. Maximum and minimum homology within the 29 Iranian strains in our study was100% and 94.9% within the carboxyl terminus of the N gene, respectively. Using ClustalX program, the alignment of Iranian MV sequences showed nine lineages.

CONCLUSION

This study provides the usefulness of MV sequence analysis for the demonstration of local interruption of indigenous strain transmission as well as providing a valuable means for monitoring the elimination processes of MV control.

[Role of Toscana virus in meningo-encephalitis in Tunisia]

OBJECTIVES

To detect the presence of Toscana virus (TOSV) circulation in Tunisia and to study its role in viral meningo-encephalitis.

PATIENTS AND METHODS

A total of 315 (167 sera and 178 cerobrospinal fluid [CSF]) samples was investigated. These samples are colleted from Tunisian patients with neurological diseases during the period between January 2003 and December 2009. All samples were tested negative for enterovirus, Herpes Simplex virus and West Nile virus. Detection for IgM and IgG specific to TOSV was done by ELISA tests.

RESULTS

Specific IgM for TOSV were detected in 10 % of patients with neurological diseases (31 cases). These recent infections were distributed throughout the study period and predominated during summer and automn. Patients were originated, in the majority from the coastal region. IgG were isolated in 22 cases (7 %) corresponding to previous infection.

CONCLUSION

This is the first report of TOSV circulating in Tunisia and its frequent implication in neurological diseases. These results incited to include TOSV as one of the viral etiologies to target in the diagnosis of viral meningitis and encephalitis in the country.

NS5A(ISDR-V3) region genetic variability of Tunisian HCV-1b strains: Correlation with the response to the combined interferon/ribavirin therapy

In the non-structural protein 5A (NS5A) of hepatitis C virus (HCV), mutations within the interferon sensitivity-determining region (ISDR), the PKR-binding domain (PKR-BD), the variable region 3 (V3), and the interferon/ribavirin resistance-determining region (IRRDR) have been correlated with the IFN-based therapy response. In Tunisia, where a high prevalence of HCV-1b has been found, no data regarding the implication of NS5A in treatment response were available. The current study examined the relationship between the pre-treatment mutation number within ISDR, PKR-BD, V3, IRRDR, as well as in the entire ISDR-V3 region of NS5A (aa 2209-2379) and the response to the 48-week course of combined IFN plus ribavirin therapy in 15 HCV-1b-infected Tunisian patients. Referring to HCV-J sequence, a significant high genetic variability was observed within PKR-BD in the sustained virological responder patients compared to non-responders (P = 0.040). More importantly, when considering the entire region from ISDR to V3, referred to as NS5A(ISDR-V3), a clear difference in the mutation number was observed between sustained virological responders (19.6 +/- 3.16) and non-responders (15.0 +/- 1.41) (P = 0.002). Additionally, a more detailed analysis of NS5A(ISDR-V3) region revealed an elevated degree of mutation rate within the region located between amino acids 2282 and 2308 (P = 0.0006). Interestingly, an analysis of specific amino acid variations defined proline and serine at position 2300 as signature patterns for sensitive and resistant strains, respectively. The genetic variability within the NS5A region of HCV-1b strains was associated with the response to the combined IFN plus ribavirin therapy in our Tunisian cohort.

[Risk of vertical transmission of hepatitis B virus in Tunisia]

The risk of vertical transmission of hepatitis B virus (HBV) varies with type of viral endemicity, degree of maternal infection and genomic characteristics of the virus. The aim of this study is to estimate this risk in Tunisia using serological and molecular methods to evaluate HBV replication, to determine viral genotypes and to detect presence of occult hepatitis in 2709 pregnant women. Serological markers were detected by ELISA methods, Genotype was determined by PCR-RFLP and occult hepatitis by nested-PCR. Four percent of women were positive for HBsAg; only 3% of them were also positive for HBeAg. Viral replication, over than 10(3) copies/ml, was detected in 61% of positive HBsAg patients. Three viral genotypes were detected: D (95%), B (3%) and A (3%). Occult hepatitis was detected in 4% of sera with "anti-HBc isolated" profile. In conclusion, the risk of vertical transmission of HBV exists in Tunisia. It increases by frequency of precore mutants, predominance of the genotype previously associated with high levels of replication and possibility of occult hepatitis B. These results show the importance of screening by serological HBV markers systematically during pregnancy with evaluation of viral replication in order to prevent vertical risk by efficient tools.

[Genetic recombination in vaccine poliovirus: comparative study in strains excreted in course of vaccination by oral poliovirus vaccine and circulating strains]

AIM OF STUDY

Recombination is one of the major mechanisms of evolution in poliovirus. In this work, recombination was assessed in children during vaccination with OPV and among circulating vaccine strains isolated in Tunisia during the last 15 years in order to identify a possible role of recombination in the response to the vaccine or the acquisition of an increased transmissibility.

MATERIAL AND METHODS

This study included 250 poliovirus isolates: 137 vaccine isolates, excreted by children during primary vaccination with OPV and 113 isolates obtained from acute flaccid paralytic (AFP) cases and healthy contacts. Recombination was first assessed using a double PCR-RFLP, and sequencing.

RESULTS

Nineteen per cent of recombinant strains were identified: 20% of strains excreted by vaccinees among 18% of circulating strains. The proportion of recombinant in isolates of serotype1 was very low in the two groups while the proportions of recombinants in serotypes 2 and 3 were different. In vaccinees, the frequency of recombinants in serotype3 decreased during the course of vaccination: 54% after the first dose, 32% after the second and 14% after the third dose.

CONCLUSION

These results suggest that recombination enhances the ability of serotype3 vaccine strains to induce an immune response. Apart from recent vaccination, it may contribute to a more effective transmissibility of vaccine strains among human population.

Association of interleukin-18 polymorphisms and plasma level with the outcome of chronic HCV infection

Hepatitis C virus (HCV) infection is the main cause of chronic liver disease throughout the world, and may progress to cirrhosis and hepatocellular carcinoma (HCC). Immunological factors, especially cytokines and some host genetic variations, rather than direct HCV action, seem to play an important role in the pathogenesis of HCV infection. Elevated levels of interleukin-18 (IL-18) were described previously for chronically (HCV)-infected patients. This study is aimed at investigating IL-18 promoter polymorphisms (-607C/A and -137G/C) in HCV-infected patients with different disease severities (chronic hepatitis C, liver cirrhosis and HCC) and establishing an association between these polymorphisms and IL-18 plasma concentration with the outcome of chronic HCV infection. The carriage of at least one C allele at position -607 (CC + CA) was associated with a higher risk of cirrhosis and HCC (P = 0.032). Compared with controls, HCV-infected patients had significantly higher levels of IL-18 (P = 0.0001) that correlate with disease severity (P = 0.01, P = 0.001, P = 0.0006, respectively). In conclusion, we supposed a possible implication of IL-18 promoter polymorphisms in the pathogenesis of chronic HCV infection.

[Seroprevalences of hepatitis A and E infections in Tunisia]

OBJECTIVE

Viral hepatitis A (HAV) and E (HEV) infections are still frequent in many regions of the world, particularly in developing countries where sanitary conditions and socioeconomic level are frequently low. In this work, we have studied seroprevalences of these two infections in Tunisian children, teenagers and young adults.

MATERIAL AND METHODS

The studied population included 3357 individuals from different regions of Tunisia and distributed in three groups 1 (n=1145), 2 (n=707) and 3 (n=1505) with a mean of age of 6.94, 12.84 and 20.71 years, respectively.

RESULTS

Rates of HAV infection prevalence of 84.0, 90.5 and 91.7% were found within groups 1, 2 and 3, respectively. These rates are lower than those previously found in the country; thus, primary infection with HAV in Tunisia is progressively shifting to older ages, which is probably due to the improvement of sanitary conditions. Lower anti-HAV prevalences were found in costal regions as compared to the rest of the country. This difference may be due to the higher socioeconomic level of the population living in costal regions. Antibodies against HEV were assessed in individuals of group 3. A seroprevalence of 4.3% was found which indicates that, despite the absence of epidemics, the virus is circulating among the Tunisian population as sporadic cases.

CONCLUSION

The present work contributes to a better knowledge of HAV and HEV infections in Tunisia and highlights the need of the establishment of a national program for virological surveillance of hepatitis cases and of further studies to monitor changes in the epidemiology of these infections.

Genetic features of polioviruses isolated in Tunisia, 1991-2006

BACKGROUND

Genetic characterisation of polioviruses remains highly important even in countries where wild poliovirus circulation has been interrupted. Sequence data on representative wild strains from all geographical regions is required for surveillance purposes and surveillance for vaccine-related isolates with increased potential for transmissibility in humans should continue.

OBJECTIVE

To report the genetic characteristics of wild and vaccine-related polioviruses isolated in Tunisia from 1991 to 2006.

STUDY DESIGN

Wild isolates were sequenced in the VP1 genomic region and compared to each other. Vaccine-related isolates were assessed for genetic recombination by PCR/RFLP and sequence analysis of the 3D region. Recombinant viruses were assessed for genetic drift in the VP1 region.

RESULTS

The VP1 sequences of the last wild isolates, all from serotype3, showed 97.7-98.7% nucleotide homology. Nineteen percent of vaccine-related isolates were vaccine/vaccine intertypic recombinants. No recombinant with non-poliovirus enteroviruses was identified. Mutational differences in the VP1 sequences of recombinant viruses ranged from 0.0% to 0.7% indicating a limited replication period.

CONCLUSIONS

This study provides sequence data on wild polioviruses from Tunisia/North Africa and shows that in countries with continuous high vaccine coverage transmission of vaccine-related polioviruses is time-limited.

Genomic stability prevails in North-African hepatocellular carcinomas

The molecular pathogenesis of hepatocellular carcinoma, a tumour characterized by a vast clinical heterogeneity, remains unexplored outside Europe and Eastern Asia. We analysed by direct sequencing or loss of heterozygosity assay, the common targets of genomic alterations in 42 hepatocellular carcinomas collected in western North-Africa. Overall, genomic instability was uncommon, allelic losses affecting mostly chromosomes 1p, 4q, 8p and 17p (24-28% of cases). CTNNB1 and TP53 were infrequently mutated (9 and 17% of cases, respectively). Surprisingly, TP53 mutation R249S, diagnostic of aflatoxin B1 exposure, usually frequent in Africa, was exceptional (one case), indicating that in western North-Africa, hepatocellular carcinoma genetics differs markedly from that of the remainder of the continent.

Molecular characterisation of a coxsackievirus A24 that caused an outbreak of acute haemorrhagic conjunctivitis, Tunisia 2003

This study reports the genetic characteristics of coxsackievirus A24 isolates from Tunisia, including a coxsackievirus A24 variant (CVA24v) that caused an outbreak of acute haemorrhagic conjunctivitis (AHC) between September and November 2003. The virus genome was detected by PCR from conjunctival swabs obtained from patients with AHC. Four virus isolates were obtained from PCR-positive samples and were serotyped by sequence analysis of the VP1 and VP4 genomic region and by seroneutralisation. Phylogenetic analysis of the VP1, VP4 and 3C genomic regions was performed. Other Tunisian CVA24 isolates from paralytic cases and healthy individuals were also amplified, sequenced and included in the phylogenetic analysis. The epidemic strain belonged to the CVA24 serotype. Phylogenetic analysis of the 3C region of the genome revealed a strong relationship between the Tunisian epidemic strain and strains that caused outbreaks in Korea (2002) and Guadeloupe and French Guiana (2003). Phylogenetic analysis of the VP1 and VP4 regions showed a clear distinction between serotype CVA24 isolates from conjunctivitis and non-conjunctivitis cases. This is the first study to report an outbreak of AHC caused by CVA24v in the North African region.

Enterovirus detection in stool specimen: relevance for poliovirus and enterovirus surveillance

Detection of enterovirus genome by PCR in clinical samples is now extensively used for the diagnostic of enterovirus infections given its rapidity and high sensitivity. In contrast, its use in surveillance programs targeting specific enterovirus serotypes remains less frequent. The most sensitive protocols are those amplifying in the 5'untranslated region (5'UTR). However the possibility to use sequence analysis of the 5'UTR amplicons for serotype identification is not yet well established. In this report, stool samples from polio suspected cases and their healthy contacts were tested. The results of direct detection of enterovirus genome by PCR and serotype identification based on sequence analysis of the PCR products in the 5'UTR were compared to those of standard cell-culture-based protocols. Standard protocols detected enterovirus isolates in 7.4% of cases while 9.8% of samples were positive by PCR. Serotype identification based on sequence analysis of amplicons showed concordant results with serotypes determined on virus isolates by seroneutralisation or sequencing in the VP1 gene in 39% of cases only. These results confirm that the use of PCR amplification from stool samples improves the sensitivity of enterovirus detection but do not recommend the use of sequence analysis of the 5'UTR PCR product to determine enterovirus serotype.

A case control study to assess risk factors for hepatitis C among a general population in a highly endemic area of northwest Tunisia

A matched case-control study was undertaken in 2004 in Béja, north-western Tunisia, to evaluate potential risk factors for hepatitis C infection. Cases were anti-HCV positive subjects screened in 1996 serosurvey. HCV seronegative controls (5 per case) were selected in the proximity of cases and matched for age and gender. A standardized questionnaire was used to collect demographic, socioeconomic, social behavior, medical and surgical history information. Matched odds ratios (OR) and adjusted OR (AOR) and their 95% CI were calculated in multivariate analysis using logistic regression. 57 HCV positive cases (mean age 61.63 +/- 14,84; 68.4 % female) and 285 HCV negative controls (mean age 60.95 +/- 14.66; 68.4 % female) were enrolled. Multivariate analysis revealed that intravenous drug injections (AOR=1.96; 95%CI[1.02-3.8] p=0.045), past history of invasive procedures (AOR=2.53; 95%CI[1.21-5.29] p=0.0014) and medical history of hypertension (AOR=2.31; 95%CI [1.17-4.56]p=0.015) were significantly associated to HCV infection. These results suggest that nosocomial transmission of HCV infection in north-west Tunisia is common.

[Identification of adenoviruses serotypes implicated in haemorrhagic conjunctivitis in Tunisia]

Human adenoviruses (ADV) are distributed worldwide; they are associated with a variety of diseases. Some ADV can be implicated in large epidemics of conjunctivitis, gastroenteritis and respiratory infections. Classical diagnosis of ADV infections is based on virus isolation on cell culture and identification of the serotype by neutralization test or hemagglutination inhibition assay. However, these methods have a lack of rapidity that makes them impractical in clinical situations. With the advent of PCR, the diagnosis of ADV was improved. In this work, we have used molecular techniques for the identification of ADV serotypes implicated in conjunctivitis in Tunisia. A total of 199 conjunctival swabs received between October 2000 and May 2005 were investigated. Serotype identification was performed using a PCR followed by restriction enzyme analysis in the hexon gene. Typing by sequencing of the PCR product was used to confirm the serotype identification. Among the 199 tested clinical specimens, 24% were positive for ADV. Two different profiles were observed: one predominant corresponding to the majority of the detected ADV; this profile is in favour of two distinct serotypes, ADV37 or ADV8; the second profile was specific of ADV4 and was found in one case observed in 2005. Sequencing confirmed two serotypes: ADV8 with an endemoepidemically circulation in our country and ADV4 that appeared sporadic. The present work showed the importance of molecular techniques not only for ADV detection but also for identification of the circulating serotypes. These techniques are practical and interesting mainly for the rapid virological investigation during epidemics.

Hepatitis B genotypes, precore and core promoter mutants circulating in Tunisia

Hepatitis B virus (HBV) is characterized by genetic heterogeneity, including genotypes and mutations. Eight genotypes (A-H) have been identified throughout the world with a characteristic geographical distribution. Previous studies also suggest that the viral genotypes may correlate with differences in clinical features of the infection. Two types of mutations were particularly described, precore and basal promoter mutations; they may play an important role in the clinical outcome of HBV infection. The aim of this study was to investigate the prevalence of HBV genotypes and HBV variants in Tunisia, and their eventual association with severity of liver disease. Using a molecular method, HBV genotypes, precore and basal core promoter mutations were determined in 56 asymptomatic carriers and in 82 patients with histologically verified chronic liver disease and hepatocellular carcinoma (HCC). Three genotypes (D, A, and E) were detected; the prevalence was 80%, 8%, and 9%, respectively. No significant difference was observed for genotype D with clinical status. HBV mutants were detected in 93% of cases, precore mutants were the most prevalent. Basal core promoter mutants were observed in 61% of cases, they were frequently characterized by a double mutation in 1762 and 1764. Co-infection by these two types of mutants was detected in 50% of cases. Genotype D was the most prevalent HBV genotype in Tunisia. High circulation of precore and basal core promoter mutants are common in chronic hepatitis B infection in Tunisia.

Contrasting patterns of hepatitis C virus infection in two regions from Tunisia

This report is a population-based study describing the pattern of hepatitis C virus (HCV) infection in two distinct regions in Tunisia. The study included a total of 11,507 individuals sampled in 1996 from both genders, all age groups, urban and rural settings belonging to 2,973 families. HCV infection was assessed by commercial enzyme immunoassay (EIA) and immunoblot assays and detection of HCV RNA by PCR. HCV genotypes and subtypes were determined by sequencing in the 5'-untranslated region (UTR) viral genomic region and the INNO-LiPA HCVII genotyping kit. Genetic relatedness between HCV strains was assessed by sequencing of a portion of the NS5B region. HCV prevalence was significantly higher in the North-Western region than in the Southern one: 1.7% versus 0.2% (P < 10(-3), chi(2) = 8,506). There was no difference in positivity according to gender or living in rural or urban settings; the only significant risk factor was advanced age. HCV prevalence among household contacts of HCV positives was not significantly higher than the prevalence in the whole study population. These results indicate a heterogeneity in the geographical distribution of HCV in Tunisia. An increased HCV transmission occurs in the North-Western region with large predominance of genotype 1b (88%) and low contribution of intrafamilial transmission.

[Blood-transmitted viral infections among haemophiliacs in Tunisia]

In this work, we proposed to evaluate prevalences of hepatitis B and C viruses and Parvovirus B19 among 70 Tunisian haemophiliacs treated with clotting factors imported from Europe and/or locally produced cryoprecipitate; among them 6 (8.6%) are known HIV positive patients. HBs antigen, anti-HBc antibodies and anti-Parvovirus B19 antibodies were detected in 7.1%, 52.9% and 91.8%, respectively. HCV prevalence, defined as positive ELISA with positive Immunoblot and/or PCR was 50.0%. Prevalences of these viral infections in haemophiliacs are higher than prevalences detected among general population and in the control group of the study. HCV infection is less frequent in haemophiliacs born after 1985, the year of introduction of the inactivation procedures in the production of coagulation factors concentrates; it decreases more considerably after 1994, date of introduction of systematic screening of HCV among blood donors. In contrast, despite the inactivation of the factors concentrates and the systematic screening of the blood donations against HBs antigen, since 1973, the risk of HBV infection contamination remains high in the Tunisian haemophiliacs. The introduction in 1995 of hepatitis B vaccination in the national schedule of new-born vaccination may resolve in the future the problem of HBV infection in haemophiliacs and in the other categories of the Tunisian population.

Enteroviruses in Tunisia: virological surveillance over 12 years (1992-2003)

This report is an overview of enterovirus epidemiology in Tunisia during a 12-year period from 1992 to 2003. A total of 4700 clinical samples were collected as part of the national poliovirus surveillance programme and the routine diagnostic programme for aseptic meningitis. Enterovirus detection was performed by isolation on cell culture according to World Health Organization recommended protocols. Serotype identification was performed by seroneutralization of the cytopathic effect using pools of specific antisera and sequencing in the VP1 region of the genome. Poliovirus isolates were assessed for their wild or vaccine-related origin by standard World Health Organization recommended methods (PCR, probe hybridization and ELISA). The results confirm the interruption of wild poliovirus circulation since 1995. A total of 236 non-polio enterovirus (NPEV) strains were isolated; seroneutralization allowed typing of 93 % (219 out of 236) of them. The antisera used allowed the identification of the most common enterovirus serotypes. The remaining 17 isolates were sequenced; 16 of them belonged to enterovirus serotypes that were not targeted by the antisera pools used. A total of 29 different serotypes of NPEV were detected in the country during the study period. Echoviruses of serotypes 6, 11 and 30 were the most frequently isolated, almost every year; other serotypes had a cyclic occurrence and others were detected during a limited period with very few isolates. The NPEV isolation rate varied from year to year but was steadily under 10 %, suggesting a relatively low prevalence of these viruses in comparison to that in other developing countries. A seasonal variation was also noted; the high transmission period starts in March and peaks in September-November. This study is the first report of the epidemiology of NPEV in Tunisia. These viruses are associated with various diseases and epidemiological data may help to clarify their impact on human health.

Étude de l’infection par le virus de la rubéole chez l’enfant et l’adolescent en Tunisie

Rubella is a worlwide common infection; its importance in public health relates to the risk of malformation when primary infection occurs during pregnancy. This serosurvey was conducted to assess the kinetics of rubella infection in Tunisian children and teenagers and to determine the proportion of girls who remain seronegative at childbearing age. The studied population included 2481 individuals aged seven (N =1136), 13 (N =711) and 19 years (N =634), this sample was collected in 1996 and is representative of all geographical regions of the country. Our results indicate that 42% of tunisians are infected before seven years, 73% before 13 and 89% before 19 years of age. These rates are lower than those previously reported in the country. The proportion of seronegatives at 19 years of age was higher in costal regions than in the rest of the country: 14 vs 5% (p =0,0008). This difference should be due to the higher socio-economic level of the population living in costal regions. Our study indicates that primary infection with rubella virus in Tunisia is progressively shifting to older ages, which may increase the risk of congenital rubella syndrome. The introduction of rubella vaccination in the national program of vaccination may be considered, however only very high coverage levels will have a positive effect. Beside the reduction of the risk of congenital rubella syndrome, rubella vaccination will reduce the incidence of febrile rush cases and thus facilitate the surveillance activities conducted as part of the national program of measles elimination.

[Role of enteroviruses in aseptic meningitis in Tunisia]

Despite the favourable clinical outcome in most cases, viral meningitis can cause a serious public health problem especially when several cases occur during outbreaks. The first part of this work is a retrospective study conducted in three hospitals in Tunisia and covering a period of three years. It showed an incidence of viral meningitis 2.4. The second part of the study is a prospective one, it included 94 cases of aseptic meningitis notified during a period of 12 months. Virus isolation in cell culture was performed on CSF and stool samples, using cell lines sensitive to enteroviruses. A PCR to detect enteroviruses was also used in parallel. This study represents a first approach to viral meningitis in Tunisia. It highlights the importance of a regular surveillance of the disease and the contribution of molecular methods to a more sensitive diagnostic. However, cell culture remained necessary for viral isolation and serotyping.

[Comparison of different methods of hepatitis C virus genotyping]

In order to introduce the approach of HCV genotyping in our laboratory, a comparative study of 3 molecular and 1 serological methods, was conducted on 62 HCV RNA positive sera. The molecular genotyping methods target the 5'untranslated (UTR) region of the virus genome and are based on an amplification of the viral genome, followed by partial sequencing, analyses of restriction fragment length polymorphisms (RFLP) or molecular hybridation (Inno LiPA, Innogenetics). The serological method or serotyping is based on the detection of antibodies to genotype specific epitopes derivated from the Non Structural (NS) 4 region of the viral genome (HCV 1-6 Serotyping Assay, Murex Biotech). "In house" methods, sequencing and RFLP, identified the genotype for 13 samples classified as non-typables by commercial kits Inno LiPA test and HCV 1-6 Serotyping Assay. Mixed infections revealed, especially by Inno LiPA, could not be identified by partial sequencing, which seems to detect only predominant genotype. For 4 samples, genotyping results of the methods targeting the 5'UTR were discordant with those of the serotyping of the NS4 region. Commercial kits are efficient to determine HCV genotypes, particularly in the context of antiviral therapy and patient's follow-up, sequencing remains the best alternative for more complete characterisation of viral strains and for epidemiological investigations.

Genotypes of hepatitis C virus circulating in Tunisia

Hepatitis C virus (HCV) isolates from 93 patients living in Tunisia, including 16 haemophiliacs, were genotyped by INNO LiPA and partial sequencing of the 5' untranslated region of the viral genome. In non-haemophiliacs, subtype 1b was largely predominant (79%), types 1a, 2a, 2b, 3a and 4a occurred much less frequently at 5, 7, 3, 3 and 1% of cases, respectively. In the group of haemophiliacs, a co-dominance between subtypes 1a and 1b was noticed (38%). Type distribution of HCV in Tunisia differs from that reported in other countries of the Mediterranean and Middle East regions. Genotyping results in respect of clinical status, age, and genotyping methods, are discussed.

[West Nile viral meningo-encephalitis in Tunisia]

In autumn 1997 an epidemic outbreak of meningoencephalitis was observed in two coastal districts of Tunisia. A total of 173 cases were recorded with 8 deaths. Detection with IgM capture and indirect IgG ELISAs demonstrated West Nile virus infection in 86% of patients from whom specimens were collected. West Nile is endemic in Asia and Sub-Saharan Africa. Epidemics in humans and horses have also been reported in the Mediterranean region and southern European countries. However this is the first report in Tunisia. Special West Nile virus surveillance is necessary especially in countries at high-risk for repeated introduction of this arbovirus.

West Nile in the Mediterranean basin: 1950-2000

Recent West Nile virus (WNV) outbreaks have occurred in the Mediterranean basin. In Algeria in 1994, about 50 human cases of WN encephalitis were suspected, including 8 fatal cases. In Morocco in 1996, 94 equines were affected of which 42 died. In Tunisia in 1997, 173 patients were hospitalized for encephalitis or meningoencephalitis. West Nile serology performed on 129 patients was positive in 111 cases (87%) including 5 fatal cases. In Italy in 1998, 14 horses located in Tuscany were laboratory confirmed for WNV infection; 6 animals died. In Israel in 1998, serum samples from horses suffering from encephalomyelitis had WNV antibodies and virus was isolated from the brain of a stork; in 1999 WNV was identified in commercial geese flocks, and in 2000 hundreds of human cases have been reported. In September 2000, WNV infection was detected in horses located in southern France, close to the Camargue National Park where a WNV outbreak occurred in 1962. By November 30, 76 cases were laboratory confirmed among 131 equines presenting with neurological disorders. No human case has been laboratory confirmed among clinically suspect patients. The virus isolated from a brain biopsy is closely related to the Morocco-1996 and Italy-1998 isolates from horses, to the Senegal-1993 and Kenya-1998 isolates from mosquitoes, and to the human isolate from Volgograd-1999. It is distinguishable from the group including the Israel-1998 and New York-1999 isolates, as well as the Tunisia-1997 human isolate.

[The isolated presence of anti-HBc antibodies: prevalence and interpretation based on the results of viral DNA research and anti-HBs antibodies measurement after vaccination]

In order to study the significance of the isolated presence of anti-HBc antibodies, we have looked for the 3 classic serological markers of the hepatitis B (HBs antigen, anti-HBs and anti-HBc antibodies) in 1,586 hospital agents who are to vaccinate in the framework of a campaign of systematic vaccination of the hospital personnel of university hospitals of Sfax for a period of 18 months. We identified subjects who presented isolated anti-HBc antibodies (33 individuals = 2.08%). In these subjects'serum, we performed a research of the DNA of hepatitis B virus (HBV) with a PCR hybridization technique using a couple of primers. One week after administration of a vaccine dose, we also measured anti-HBs antibodies in their sera. Among the tested 18 personnel with anti-HBc isolated antibodies, 11.1% had low rates of anti-HBs antibodies indicating that there is presumably primary antibody response and therefore a false positivity of anti-HBc antibodies in pre-vaccinal serology; while 11.1% others had higher rates of anti-HBs antibodies corresponding to a secondary antibody response, which witness a previous HBV immunisation. The research of the HBV-DNA was positive in 11.1% of tested personnel, testifying a presumably chronic portage of the virus with low rates of the HBs antigen undetectable with the serological techniques. For the remainder subjects with isolated anti-HBc antibodies (66.7%), the interpretation remains ambiguous.

High circulation of hepatitis B virus (HBV) precore mutants in Tunisia, North Africa

Hepatitis B Virus (HBV) e antigen (HBeAg), HBV DNA and precore mutations affecting HBeAg expression during active replication were studied in 72 Tunisian hepatitis B surface antigen (HBsAg) positive individuals: 30 asymptomatic carriers of the virus, 37 with chronic hepatitis and 5 with acute hepatitis. HBV DNA was detected in 44 patients, but only 20% of them expressed HBeAg. Precore mutant strains, with mutations at position 1896 or at positions 1896 and 1899, were detected by PCR-hybridization in 86 and 36% of patients, respectively. Wild-type strains were detected in 54% of patients. Precore mutants were found in chronically and in acutely infected individuals, in patients with severe and asymptomatic infections, in HBeAg positive as well as HBeAg negative individuals. These results show the high frequency of HBV precore mutants in Tunisia.

Molecular epidemiology of poliovirus infection in Tunisia

This report is an overview of poliomyelitis surveillance in Tunisia from 1991 to 1996. In all, 2088 stool specimens, collected from 152 acute flaccid paralysis (AFP) cases and from 1747 of their healthy contacts were investigated. Virus isolation was done systematically in RD and HEp-2C cell lines and isolated viruses were typed by sero-neutralisation as polioviruses or non-polio enteroviruses. Poliovirus isolates were analysed systematically for their wild or vaccine-related origin by two methods--one based on antigenic differences and one on genetic differences between strains. All type 2 polioviruses were vaccine-related and most wild viruses belonged to polio serotype 3. Wild polio type 3 viruses were detected in 1991 and 1992 in six cases of paralytic polio. A silent circulation of wild polio 1 and wild polio 3 was detected in 1994. No wild virus was detected in Tunisia from 1995 onwards. Wild polioviruses were sequenced and compared with Tunisian wild strains isolated during the 1980s, as well as other genotypes from the international database. These investigations revealed a single Tunisian polio 3 genotype that has been circulating from 1985 to 1994 and two different polio 1 genotypes. These results reflect effective control strategies within the country and contribute to the improvement of the polio eradication programme effectiveness at national and global levels.

[Isolated traumatic anterior dislocation of the radial head]

The authors report 2 cases of isolated traumatic anterior dislocation of the radial head in children. In the first case, with an acute dislocation, closed reduction followed by plaster cast immobilisation for one month gave a good result. In the second case, the dislocation was also traumatic in origin but had remained unreduced for 5 years. Arthrography of the elbow showed the head to be intracapsular. The authors believe that a neocapsule forms in cases of old unreduced dislocation and arthrography is therefore of little help to differentiate a long standing traumatic dislocation from a congenital dislocation. Based on their experience and on the literature, the authors propose closed reduction followed by immobilisation as a treatment for acute dislocation; old unreduced dislocations cannot be reduced by manipulation and with the exception of very symptomatic cases, the authors prefer to avoid open reduction, which carries a risk of joint stiffness.

Influence of host related factors on the antibody response to trivalent oral polio vaccine in Tunisian infants

The low efficiency of trivalent oral polio vaccine (TOPV) in inducing protective antibody titres to polio3 is a problem of great importance in many regions of the world. A prospective study was conducted in 121 Tunisian infants aged 3 months during routine immunization with TOPV under carefully controlled conditions. Seroconversion rates to polio1, polio2 and polio3, one month after the third dose, were 94.7, 100 and 89.5%, respectively. The kinetics of the antibody response showed delayed and more difficult responses to polio3 compared to polio2 and polio1. The following host related factors, previously suggested to interfere with the immune response, were assessed: maternal antibodies; breast-feeding; concurrent enteric infections; and other illnesses. The main factor associated with the lack of seroconversion was concurrent infection with non-polio enteroviruses (NPE) which was found in 50% of non-responders to polio1 and/or to polio3 during the vaccination protocol whereas no NPE was isolated in vaccine responders. The other studied factors seemed not to interfere in the infants according to the locally adopted vaccination schedule and to the specific socio-economic conditions.

Effect of laser irradiation on latency of herpes simplex virus in a mouse model

Low power Laser irradiation is used in medical practice for different indications. Several firms which commercialise Laser claim that Laser irradiation may be beneficial towards Herpes virus pathogenicity. We observe that, in the ear experimental model of HSV latency [3], repeated exposure to infrared Laser radiation of cervical ganglia following HSV inoculation appears to specifically hinder the establishment of virus latency in mouse.