Detection and genotyping of group A rotaviruses isolated from sewage samples in Monastir, Tunisia between April 2007 and April 2010.

AIMS: To ascertain the viral load, the distribution of G and P types of group A rotaviruses (RV-A) in sewage samples and to compare strains in clinical, animal and environmental samples. METHODS AND RESULTS: During our study from April 2007 to April 2010, 518 samples of raw and treated sewage were collected from two biological sewage treatment plants (STPs) located in the Monastir region, Tunisia. RV-A was detected by real-time RT-PCR in 375 (72·4%) sewage samples. According to the quantification results of RV-A, it appears that the viral load in raw and treated sewage of the two STPs was quite similar (P = 0·735). The genotyping of RV-A strains detected in sewage samples showed a great diversity with 10 G types and 8 P types. Most of them were described as common in humans, but we also detected genotypes commonly found in animals. All the genotypes detected in two previous studies performed in our laboratory on clinical and bovine samples were also found in environmental samples. However, some genotypes commonly found in animal were only found in sewage samples. CONCLUSION: The comparison of environmental, clinical and animal data suggests that STPs may convey not only human sewage but also animal wastes, both of them contaminated with numerous RV-A strains which are not efficiently eliminated by the sewage treatment process and may spread to surface waters. SIGNIFICANCE AND IMPACT OF THE STUDY: This work demonstrates the potential release of human and animal RV-A into water sources, representing a public health risk, by inducing gastroenteritis in population, but also by increasing the risk of zoonotic transmission and formation of reassortant viruses which could get a higher infectious potential. Our findings also suggest that monitoring of sewage may provide an additional tool to determine the epidemiology of RV-A circulating in a given community.

Hepatitis E virus genotypes 1 and 3 in wastewater samples in Tunisia.

Hepatitis E represents an important public-health concern throughout the world. It is one of the leading causes of hepatitis in North Africa, Asia and the Middle East. In Tunisia, the true burden of HEV infection is still unknown. The objectives of the present study were to assess the occurrence of hepatitis E virus in Tunisia through the monitoring of urban sewage and to characterize the strains identified using molecular assays. A total of 150 sewage samples (raw and treated) were collected from three wastewater treatment plants located in the regions of Monastir and Mahdia and analyzed by nested RT-PCR using a qualitative assay targeting the methyltransferase gene in ORF1. Of these, only three samples (2 %) were found to be positive for HEV, one belonging to genotype 1 and two to genotype 3. The results of the present study indicate a low level of virus excretion among the Tunisian population. Both genotypes 1 and 3 are circulating in this country, however, possibly causing sporadic infections. The presence of the zoonotic genotype 3, known to be transmitted to humans mainly by swine and demonstrated in Tunisia for the first time in this work, raises the question of possible reservoir species, since pork products are not consumed in this country, pigs are not bred, and wild boar is not endemic. Further studies will be needed to gather information on the occurrence and diversity of HEV strains circulating among humans and animals in Tunisia, and on possible animal reservoirs.

Qualitative and Quantitative Assessment of Hepatitis A Virus in Wastewaters in Tunisia.

Hepatitis A causes substantial morbidity in both industrialized and non-industrialized countries and represents an important health problem in several southern Mediterranean countries. The objectives of the study were as follows: (a) to assess the occurrence of hepatitis A virus (HAV) in Tunisia through the monitoring of urban wastewaters collected at wastewater treatment plants (WTPs); (b) to characterize environmental strains; and (c) to estimate the viral load in raw and treated sewages, in order to evaluate the potential impact on superficial waters receiving discharges. A total of 150 raw and treated wastewaters were collected from three WTPs and analyzed by both qualitative (RT-PCR/nested) and quantitative (qRT-PCR) methods. Of these, 100 (66%) were found to be positive for HAV by the qualitative assay: 68.3% in influents and 64.7% in effluents. The vast majority of HAV sequences belonged to sub-genotype IA, with 11 different strains detected found to be identical to clinical strains isolated from Tunisian patients with acute hepatitis. Five unique variants were also detected, not previously reported in clinical cases. Only two IB strains were found, confirming the rarity of this sub-genotype in this country. The results of the present study indicate a wide circulation of the pathogen in the population, most probably in the form of asymptomatic infections, a finding consistent with the classification of the country as having intermediate/high endemicity. Quantitative data showed high viral loads in influents (3.5E+05 genome copies/liter, mean value) as well as effluents (2.5E+05 genome copies/liter, mean value), suggesting that contaminated water could be a critical element in transmission.

Distribution of G (VP7) and P (VP4) genotypes of group A bovine rotaviruses from Tunisian calves with diarrhoea.

AIMS: To investigate the incidence, viral load and genetic diversity of bovine rotaviruses strains in Tunisia. METHODS AND RESULTS: A total of 169 faecal specimens, collected from diarrhoeic calves from several farms located in the central eastern regions of Tunisia, between January 2006 and October 2010, were analysed by semi-nested multiplex RT-PCRs for P and G genotypes identification or were genotyped by DNA sequencing. Positive samples were tested by TaqMan real-time RT-PCR to quantify the viral load. Group A bovine rotaviruses were detected in 15·4% (26/169) of the total studied cases of diarrhoea. Overall, G10 was the predominant G type, detected in 12/26 samples (46·2%) and G6 accounted for 42·3% (11/26) while P[11] was the predominant P type, detected in 12/26 samples (46·2%). Two P[5] genotypes (7·7%) were found in the collection. Dual G or P combination and genotype G8 were not found. The most common VP7/VP4 combinations were G6P[11] (30·8%; n = 8) and G10P[11] (11·5%; n = 3). The combination G10P[14] was seen in one sample, and partial typing was assessed in 53·8% (n = 14) of the cases. The viral load determined by real-time RT-PCR showed an average of 1·68 × 10(9) genome copies/g of faeces. CONCLUSION: Knowledge of P and G types could help us understand the relatedness of animal rotaviruses to viruses causing disease in humans. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that the viral load and P types of bovine rotaviruses have been determined in Tunisia, and this study contributes to a better understanding of the epidemiology of such viruses circulating in Tunisia. Nevertheless, continuous surveillance is necessary to detect the emergence of new variants.