Hepatitis E virus (HEV) infection occurs in an estimated 20 million individuals, leading to an estimated 3.3 million symptomatic cases in developing and developed countries worldwide (1). Infection by HEV genotypes 1 and 2, which infect humans via the fecal-oral routes through the intake of contaminated foods and water, has mainly been reported in Southeast Asia and Mexico (2-5). HEV genotypes 3 and 4 are associated with zoonotic infection and are observed worldwide (6-9).

Acute hepatic insult manifesting as jaundice and coagulopathy, and complicated within 4 weeks by ascites and/or encephalopathy in patients with previously diagnosed or undiagnosed chronic liver disease is defined as acute-on-chronic liver failure (ACLF) (10). HEV genotype 1 plays a crucial role in acute viral hepatitis and ACLF in developing countries (11). Acute HEV genotype 1 infection is a leading cause of ACLF in Bangladesh and India (12,13).

HEV genotype 3 can also induce chronic infection in immunocompromised individuals and ACLF in patients with underlying liver disease (14-16). It has been reported that patients with HEV genotype 3 or 4 are susceptible to treatment with ribavirin (16).

Recently, the authors treated a Japanese male patient with severe acute HEV genotype 3b infection and alcohol-associated liver disease. The present study reports this case and discusses the possibility of ACLF induced by HEV genotype 3 infection and its treatment.

A patient male in his 70s who consumed alcohol experienced abdominal distention, loss of appetite, epigastric pain and dark urine (jaundice). After 5 days, he visited the local clinic near his residence, and the worsening of his liver function was observed by the obtained test results. The following day, he was referred and admitted to Nihon University Itabashi Hospital (Tokyo, Japan).

Due to the patient's history of cerebral infarction, hypertension, diabetes mellitus and hyperuricemia, he regularly visited the local clinic. Aspirin, valsartan, amlodipine besylate, furosemide, sitagliptin phosphate hydrate, ipragliflozin L-proline, febuxostat and magnesium oxide were prescribed. He had also undergone surgery for his springer finger, and cefaclor, loxoprofen sodium salt and lebamipide were prescribed. He began to consume alcohol at 12 years of age. He had also consumed horse sashimi 1 month prior. He had no history of transfusion, tattooing, drug abuse or drug allergies, and had not recently traveled abroad. He had no family history of liver disease.

The height of the patient was 161 cm and his body weight was 69 kg. His blood pressure, pulse rate and body temperature were 157/93 mmHg, 71/min and 36.1˚C, respectively. A physical examination revealed that he was conscious; he had hepatic encephalopathy grade <2, and he had conjunctival icterus. Abdominal distention was observed.

The laboratory data of the patient obtained upon admission are presented in Table I, indicating marked liver dysfunction and a history of hepatitis B virus (HBV) infection. At 2 weeks following admission, positivity for anti-HEV immunoglobulin A (IgA) antibody (Institute of Immunology, Co. Ltd., Tokyo, Japan) was revealed. The patient was found to be HEV RNA-positive and he had acute HEV genotype 3b infection, as determined according to previously described methods (17). Furthermore, using stored serial serum samples, the IgG, IgM and IgA classes of HEV antibodies were determined as previously described (18), and all these HEV antibodies tested positive until the end of the observation period (day 83) (Table II). He also had chronic kidney disease with a severely decreased estimated glomerular filtration rate (category G4) (19) and type 2 diabetes mellitus.

An abdominal computed tomography scan indicated an atrophic liver and cirrhosis, although no gastrointestinal varices were present, according to the endoscopy (Fig. 1). An abdominal ultrasound sonography revealed collateral veins and splenomegaly; his liver stiffness was 41.2 kPa according to transient elastography, indicating liver cirrhosis and inflammation, although he never experienced any episodes of ascites, jaundice, hepatic encephalopathy, or variceal bleeding (20). The patient was diagnosed with severe acute HEV genotype 3b and alcohol-associated liver cirrhosis.

Due to his alcohol consumption shortly prior, indications for liver transplantation were not assessed. As ribavirin could not be used due to renal dysfunction (21), only conservative treatment was administered. However, his abnormal liver function tests gradually improved, although his HEV RNA was detectable by the highly sensitive nested reverse transcription-polymerase chain reaction with primers targeting the ORF2/ORF3 overlapping region (22) until day 32 after admission. The peak alanine aminotransferase (ALT) and total bilirubin levels were 1,067 IU/l and 26.3 mg/dl, respectively. He was ultimately discharged, and he left the hospital on foot on day 43 (Table II and Fig. 2).

Barbosa et al (21) reported four ACLF/death patients with an HEV genotype 3 infection, and HEV should be considered an acute insult in the acute decompensation of cirrhosis and ACLF. The present study also observed ACLF, which was associated with HEV genotype 3b and alcohol-induced acute insult and chronic liver disease in a patient in Japan.

Barbosa et al (21) reported that 50% of the patients with HEV genotype 3 infection were male, the median age was 63 years (range, 51-76 years), and the median ALT level at presentation was 2,486 U/l (range, 1,146-3,134 U/l) in the majority of cases of HEV-related ACLF. Among the causes of cirrhosis in these 4 patients, in 1 and 3 patients, this was caused by non-alcoholic steatohepatitis and alcohol-use, respectively (21). The data of the patient described in the present study were in agreement with this previous report (21).

The peak ALT level was 1,067 IU/l in the present case. High ALT levels may provide an indication for the diagnosis of acute HEV infection (21,23). Barbosa et al (21) also used ribavirin in 3 patients; however, in the present study, ribavirin could not be used due to renal dysfunction. In general, pregnancy, severe anemia or renal dysfunction prohibit the use of ribavirin.

Although the present study did not measure HEV viral loads, HEV RNA became undetectable on day 34 in the present case (Table II). It appears to be more beneficial for patients to eradicate the hepatitis virus causing the hepatitis. More effective anti-HEV drugs need to be developed for severe HEV infection, particularly, in pregnant females (24). HEV-infected patients with cirrhosis with or without HBV infection may develop ACLF, which is associated with a high mortality rate (~70%) (25-27).

The patient in the present study had consumed horse sashimi approximately 1 month prior to the onset of his symptoms, such as abdominal distention, loss of appetite, epigastric pain and dark urine (jaundice). It has been reported that anti-HEV IgG antibody and/or HEV RNA are positive in workhorses or horses in Egypt (28), China (29), the Netherlands (30), Bulgaria (31) and Germany (32). However, since whether horses play a role in the transmission of HEV remains unknown, further studies are warranted in this regard.

HEV has been reported to be the most common cause of infection in 95 (46.1%) of 206 patients with acute sporadic viral hepatitis and 60 (67.4%) of 89 patients with ACLF in India, an endemic country of HEV genotype 1 infection (11). Lim et al (33) reported that a 59-year-old Caucasian male acquired HEV infection and fatal hepatic decompensated alcohol-associated liver cirrhosis in the United Kingdom, where the HEV genotype 3 is a major genotype. Fantilli et al (34) reported that HEV genotype 3 infection in a patient with alcohol-associated liver disease developed ACLF in Argentina.

To the best of our knowledge, there are two reported cases from Japan, where patients with primary biliary cholangitis were infected with HEV genotype 3b (35,36). Of these 2 patients, 1 patient succumbed due to the rupture of hepatocellular carcinoma (36). Another study reported that a 49-year-old male with excessive alcohol consumption and acute HEV genotype 4 infection developed acute liver failure (37). Thus, HEV genotype 3 or HEV genotype 4 is also a key acute insult in ACLF. Of interest, among patients with alcohol-associated liver cirrhosis, a higher prevalence of anti-HEV IgG has been observed in Poland (38) and Argentina (39).

Pegylated interferon-α with or without ribavirin may play a role in eradicating HEV in some patients, although pegylated interferon-α has more side-effects (40). Several drugs, such as interferon-λ, sofosbuvir, azithromycin and ritonavir, exert anti-viral effects on HEV replication in vitro (41,42). Further studies are required for the development of drugs against HEV infection.

In conclusion, careful attention should be paid to viral hepatitis, including hepatitis E, in patients with alcohol-associated liver disease. Further research and the development of novel drugs for HEV infection are required for the prevention of severe HEV infections.