5 ǀ HEV IN WATER AND WATER-BORNE OUTBREAKS
Genotypes 1 and 2 are mainly reported in Asia including Afghanistan, India, Bangladesh, China, Nepal, and Pakistan, and some African countries such as Chad, the Central African Republic, Mexico, Nigeria, and Sudan.112 Genotype 1 and possibly 2 caused several water-borne outbreaks in many parts of the world.3,24,113 Qualitative analysis of drinking and sewage water samples by using RT-PCR from Faisalabad, Pakistan, showed the presence of HEV genotype 1 strain.114 Another study from Italy reported a high prevalence of HEV in water samples with the presence of HEV genotype 1 and 3 in sewage water samples in which 11 out of 19 WWTPs were positive for HEV RNA.96
In Spain, the HEV genome was detected from slaughterhouse sewage mainly from pigs and showed 92-94% nucleotide similarity with strain detected from the human.115 A high positivity rate of 20/46 (43.5%) of HEV was reported in sewage samples from Barcelona, Spain.116 Another study from Spain showed the presence of both genotypes 1 and 3 in samples from WWTPs.117 In Spain, the HEV genotype 1 and 3 were detected from sewage and biosolid samples from urban sewage treatments.118 In Colombia of the total sixty environmental samples, the HEV genome was detected in 23.3% (7/30) of drinking water plants/creek and in 16.7% (5/30) of sewage samples.119 Several HEV outbreaks have been reported in some countries in particular in developing countries. The recent HEV outbreaks associated with water contamination are presented in Table 1.