Hepatitis A and Hepatitis E: Clinical and Epidemiological Features, Diagnosis, Treatment, and Prevention.

Hepatitis A and E are both ancient diseases but have only been properly recognized as being caused by distinct pathogens in modern times. Despite significantly different genomic structures, both viruses employ remarkably similar strategies to avoid host detection and increase environmental transmission. There are millions of cases of acute viral hepatitis due to hepatitis A virus (HAV) and hepatitis E virus (HEV) each year, resulting in tens of thousands of deaths. The presentations can be clinically indistinguishable, but each virus also has a range of less common but more specific phenotypes. The epidemiology of HAV is complex, and is shifting in countries that are making improvements to public health and sanitation. HEV presents a significant public health challenge in resource-limited settings but has historically been incorrectly regarded as having little clinical relevance in industrialized countries.

Hepatitis E virus infection and acute non-traumatic neurological injury: A prospective multicentre study.

BACKGROUND & AIMS: Hepatitis E virus (HEV) has been associated with a number of neurological syndromes, but causality has not yet been established. The aim of this study was to explore the relationship between HEV and neurological illness by prospective HEV testing of patients presenting with acute non-traumatic neurological injury. METHODS: Four hundred and sixty-four consecutive patients presenting to hospital with acute non-traumatic neurological illnesses were tested for HEV by serology and PCR from four centres in the UK, France and the Netherlands. RESULTS: Eleven of 464 patients (2.4%) had evidence of current/recent HEV infection. Seven had HEV RNA identified in serum and four were diagnosed serologically. Neurological cases in which HEV infection was found included neuralgic amyotrophy (n=3, all PCR positive); cerebral ischemia or infarction (n=4); seizure (n=2); encephalitis (n=1); and an acute combined facial and vestibular neuropathy (n=1). None of these cases were clinically jaundiced and median ALT at presentation was 24IU/L (range 8-145). Cases of HEV-associated neuralgic amyotrophy were found in each of the participating countries: all were middle-aged males with bilateral involvement of the brachial plexus. CONCLUSIONS: In this cohort of patients with non-traumatic neurological injury, 2.4% had evidence of HEV infection. Symptoms of hepatitis were mild or absent and no patients were jaundiced. The cases of HEV-associated neuralgic amyotrophy had similarities with other HEV-associated cases described in a large retrospective study. This observation supports a causal relationship between HEV and neuralgic amyotrophy. To further understand the relevance of HEV infection in patients with acute neurological illnesses, case-control studies are warranted. Lay summary: Hepatitis E virus (HEV), as its name suggests, is a hepatotropic virus, i.e. it causes damage to the liver (hepatitis). Our findings show that HEV can also be associated with a range of injury to the nervous system.

Hepatitis E Virus: Time to Change the Textbooks.

Until recently, hepatitis E virus (HEV) was thought not to occur in developed countries. It is now clear that locally acquired HEV is common in such settings. HEV infection acquired in these areas differs from that in developing countries in a number of important aspects: it is caused by genotype 3 (and 4 in China and Japan), it mainly affects middle-aged/elderly males and it is zoonotic with a porcine primary host. Pig herds worldwide are infected with HEV genotype 3 and HEV has been found in the human food chain in a number of developed countries. However, the route of transmission is not fully understood, since most cases are not obviously associated with pigs/pig products. HEV can be transmitted by blood transfusion and surprisingly high numbers of asymptomatic blood donors are viremic at the time of donation: Germany 1:1,200, Netherlands 1:2,671, England 1:2,848. Our understanding of the clinical phenotype of HEV infection in humans has undergone a sea-change in recent years. Previously, HEV was thought to cause only acute self-limiting hepatitis. However, HEV may cause persistent disease in the immunocompromised. Patients with chronic HEV infection have no symptoms, but some develop rapidly progressive liver cirrhosis. The full clinical spectrum of HEV is still emerging. HEV has important extra-hepatic manifestations, which deserve further investigation. For example, HEV can cause a wide range of neurological illness. In particular, very recent data suggest that Guillain-Barré syndrome and neuralgic amyotrophy are associated with locally acquired HEV in approximately 5 and 10% of the cases, respectively.

Hepatitis E: an underestimated emerging threat.

Hepatitis E virus (HEV) is the most common cause of viral hepatitis in the world. It is estimated that millions of people are infected every year, resulting in tens of thousands of deaths. However, these estimates do not include industrialized regions and are based on studies which employ assays now known to have inferior sensitivity. As such, this is likely to represent a massive underestimate of the true global burden of disease. In the developing world, HEV causes large outbreaks and presents a significant public-health problem. Until recently HEV was thought to be uncommon in industrialized countries, and of little relevance to clinicians in these settings. We now know that this is incorrect, and that HEV is actually very common in developed regions. HEV has proved difficult to study in vitro, with reliable models only recently becoming available. Our understanding of the lifecycle of HEV is therefore incomplete. Routes of transmission vary by genotype and location: endemic regions experience large waterborne epidemics, while sporadic cases in industrialized regions are zoonotic infections likely spread via the food chain. Both acute and chronic infection has been observed, and a wide range of extrahepatic manifestations have been reported. This includes neurological, haematological and renal conditions. As the complete clinical phenotype of HEV infection is yet to be characterized, a large proportion of cases go unrecognized or misdiagnosed. In many cases HEV infection does not feature in the differential diagnosis due to a lack of knowledge and awareness of the disease amongst clinicians. In combination, these factors have contributed to an underestimation of the threat posed by HEV. Improvements are required in terms of recognition and diagnosis of HEV infection if we are to understand the natural history of the disease, improve management and reduce the burden of disease around the world.

Investigation of liver dysfunction: who should we test for hepatitis E?

AIM: Hepatitis E virus (HEV) is endemic in developed countries, but unrecognized infection is common. Many national guidelines now recommend HEV testing in patients with acute hepatitis irrespective of travel history. The biochemical definition of 'hepatitis' that best predicts HEV infection has not been established. This study aimed to determine parameters of liver biochemistry that should prompt testing for acute HEV. METHODS: This was a retrospective study of serial liver function tests (LFTs) in cases of acute HEV (n=74) and three comparator groups: common bile duct stones (CBD, n=87), drug-induced liver injury (DILI, n=69) and patients testing negative for HEV (n=530). To identify the most discriminating parameters, LFTs from HEV cases, CBD and DILI were compared. Optimal LFT cutoffs for HEV testing were determined from HEV true positives and HEV true negatives using receiver operating characteristic curve analysis. RESULTS: Compared with CBD and DILI, HEV cases had a significantly higher maximum alanine aminotransferase (ALT) (P<0.001) and ALT/alkaline phosphatase (ALKP) ratio (P<0.001). For HEV cases/patients testing negative for HEV, area under receiver operating characteristic curve was 0.805 for ALT (P<0.001) and 0.749 for the ALT/ALKP ratio (P<0.001). Using an ALT of at least 300 IU/l to prompt HEV testing has a sensitivity of 98.6% and a specificity of 30.3% compared with an ALT/ALKP ratio higher than or equal to 2 (sensitivity 100%, specificity 9.4%). CONCLUSION: Patients with ALT higher than or equal to 300 IU/l should be tested for HEV. This is simple, detects nearly all cases and requires fewer samples to be tested than an ALT/ALKP ratio higher than or equal to 2. Where clinically indicated, patients with an ALT less than 300 IU/l should also be tested, particularly if HEV-associated neurological injury is suspected.

Hepatitis E virus: Western Cape, South Africa.

AIM: To conduct a prospective assessment of anti-hepatitis E virus (HEV) IgG seroprevalence in the Western Cape Province of South Africa in conjunction with evaluating risk factors for exposure. METHODS: Consenting participants attending clinics and wards of Groote Schuur, Red Cross Children's Hospital and their affiliated teaching hospitals in Cape Town, South Africa, were sampled. Healthy adults attending blood donor clinics were also recruited. Patients with known liver disease were excluded and all major ethnic/race groups were included to broadly represent local demographics. Relevant demographic data was captured at the time of sampling using an interviewer-administered confidential questionnaire. Human immunodeficiency virus (HIV) status was self-disclosed. HEV IgG testing was performed using the Wantai® assay. RESULTS: HEV is endemic in the region with a seroprevalence of 27.9% (n = 324/1161) 95%CI: 25.3%-30.5% (21.9% when age-adjusted) with no significant differences between ethnic groups or HIV status. Seroprevalence in children is low but rapidly increases in early adulthood. With univariate analysis, age ≥ 30 years old, pork and bacon/ham consumption suggested risk. In the multivariate analysis, the highest risk factor for HEV IgG seropositivity (OR = 7.679, 95%CI: 5.38-10.96, P < 0.001) was being 30 years or older followed by pork consumption (OR = 2.052, 95%CI: 1.39-3.03, P < 0.001). A recent clinical case demonstrates that HEV genotype 3 may be currently circulating in the Western Cape. CONCLUSION: Hepatitis E seroprevalence was considerably higher than previously thought suggesting that hepatitis E warrants consideration in any patient presenting with an unexplained hepatitis in the Western Cape, irrespective of travel history, age or ethnicity.