Viral Hepatitis: Acute Viral Hepatitis and the Fecal-Oral Viruses

0:00Welcome to Board Pearls. This is episode one of three of the Viral Hepatitis chapter, in the Liver Disease module. This episode is the acute viral hepatitis framework and the two fecal-oral viruses: the phases of acute hepatitis, the serologic panel that reads the virus, hepatitis A as the post-exposure prophylaxis decision, and hepatitis E with its high mortality in pregnancy and chronic infection in the immunocompromised.

0:27Start with the observation that organizes the whole chapter: acute viral hepatitis looks essentially the same regardless of which virus caused it, so you can't read the virus off the symptoms, you read it off the serology. That single fact is why the first move on any acute hepatitis stem is the panel, not the history, and why the pattern recognition lives in the lab data. The mechanism is the same across viruses: a hepatotropic virus reaches the liver, replicates silently during incubation, then provokes an immune response that produces the symptomatic illness, with the injury partly direct and partly immune-mediated. The course walks through three phases similar enough across viruses that the boards expect you to apply them generically. The prodrome, after incubation, is malaise, anorexia, nausea, low-grade fever, and right-upper-quadrant discomfort, a flu-like syndrome, sometimes with a serum-sickness component of rash, hives, or arthralgia, which is most characteristic of hepatitis B and driven by immune complexes containing the surface antigen. The incubation runs about a month for hepatitis A, a couple to a few months for hepatitis B, and a few weeks for hepatitis C. The icteric phase follows over days, with dark urine, pale stools, and jaundice, transaminases now in the hundreds to thousands and a rising conjugated bilirubin, and the interesting point is that turning yellow is the minority pattern in immunocompetent adults with acute hepatitis B, since only a minority become icteric and most acute infections are silent, so the jaundiced patient is the recognizable case, not the typical one. The convalescent phase comes next, where symptoms remit before the labs normalize, the transaminases drift down over weeks and the bilirubin trails behind, so a patient who feels recovered with transaminases still in the low hundreds is on track, not failing.

2:13Within that clinical envelope, the differential is built almost entirely from the serologic panel. The first-line acute panel is four tests: the hepatitis B surface antigen, the hepatitis B core IgM, the hepatitis C antibody with reflex to RNA, and the hepatitis A IgM, with hepatitis E IgM added in the returning traveler from south Asia or Africa, the person with substantial pork or game ingestion, or whenever the conventional panel is negative and the cause is unclear. The interpretation rules are precise and worth owning as reflex: surface antigen positive with core IgM positive is acute hepatitis B; surface antigen positive with core IgM negative but total core positive is chronic hepatitis B; hepatitis C antibody positive with RNA positive is hepatitis C infection, acute or chronic; hepatitis A IgM positive is acute hepatitis A; and hepatitis E IgM positive supports acute hepatitis E, with the RNA adding value in the immunocompromised host where the antibody response can be blunted. Two named traps live inside that panel. The first is hepatitis C: the antibody can be negative for the first couple of months of acute infection because seroconversion lags viremia, so a high-suspicion patient with a negative antibody isn't cleared, and the test that closes the question is the RNA, positive once viremia is present whether or not the antibody has caught up. The second is hepatitis B: the core IgM defines acute infection in most settings but can repositivate during a chronic flare, so a chronic patient who suddenly has IgM positivity isn't necessarily newly infected, and the workup mirrors the acute panel plus hepatitis D testing. The reason this serology-driven approach is right is that the prodromal and icteric phases are similar enough that history alone can't distinguish the viruses, so the traveler with hepatitis A, the man with acute hepatitis B, and the patient with acute hepatitis C from injection drug use all present the same way, and the differentiator is the panel, not the story.

4:12A few other items belong in the same folder: acute autoimmune hepatitis can closely mimic acute viral hepatitis and is sometimes triggered by it, drug injury is excluded by the medication history, ischemic hepatitis produces transaminases in the thousands but falls fast after the perfusion insult resolves, and acute Budd-Chiari and biliary obstruction round out the list. The alarm features that move a patient out of supportive care and into transplant evaluation are a rising INR, deepening jaundice beyond about four weeks, encephalopathy of any grade, and clinical decompensation, and while acute hepatitis A and B rarely fulminate in healthy adults, the rate is materially higher in three settings, hepatitis B plus D coinfection, hepatitis E in pregnancy, and any acute hepatitis on top of chronic liver disease. Treatment branches by virus: acute hepatitis A is supportive; acute hepatitis B is observed and treated with a nucleoside analog only in the small minority with fulminant or protracted severe disease, with interferon contraindicated; acute hepatitis C is treated promptly with a direct-acting antiviral once viremia is documented, because the chronicity rate is high and waiting for spontaneous clearance trades cures for chronic disease; and acute hepatitis D and E are supportive in the acute phase, with the exceptions for E coming later.

5:33That sets up the two fecal-oral viruses. Hepatitis A is a picornavirus transmitted fecal-orally, with an incubation of about a month and the canonical prodrome-jaundice-recovery course, transaminases often into the thousands, symptoms resolving as jaundice appears, and full recovery in most adults with no chronic infection, which is its cardinal property, so hepatitis A IgM positive means you don't plan for chronic disease. The risk factors are travel to endemic areas, men who have sex with men, food workers, homelessness, injection drug use, and contaminated-produce or shellfish outbreaks, and fulminant failure is rare and concentrated in two groups, patients over fifty and patients with underlying chronic liver disease, which is why hepatitis A vaccination is recommended in all patients with chronic liver disease of any cause, since a superimposed acute hepatitis A in a cirrhotic or a chronic hepatitis B or C patient decompensates at a much higher rate than in a healthy adult. A few atypical presentations are worth holding: a small fraction develop a prolonged cholestatic variant with bilirubin elevated for months and pruritus, managed supportively with recovery; a smaller fraction relapse in cycles; and a recognized but uncommon hepatitis-A-induced autoimmune hepatitis appears weeks to months later with hypergammaglobulinemia and autoantibodies, treated with the standard regimen, so the pearl is that an acute hepatitis that doesn't resolve on schedule or acquires the autoimmune phenotype may have started as hepatitis A.

6:59The hepatitis A vaccine is two doses a month apart and is highly protective. The list of indications is long enough that the principle beats the list: vaccinate anyone at elevated exposure risk and anyone for whom acute hepatitis A would be more dangerous than in an average healthy adult, meaning travelers, men who have sex with men, drug users, and the homeless, plus contacts of international adoptees, certain occupational exposures, recipients of clotting-factor concentrates, and all patients with chronic liver disease, that last indication being the easiest to forget and the most consequential. Post-exposure prophylaxis is the highest-yield decision point, and the choice between vaccine and immunoglobulin tracks the host's ability to mount a rapid antibody response: immunocompetent persons from twelve months to forty years get a single dose of vaccine within two weeks of exposure, while persons over forty, the immunocompromised, those with chronic liver disease, and infants under twelve months get immunoglobulin within two weeks, since the healthy young adult seroconverts fast enough that the vaccine catches the incubation window while the older or immunocompromised host does not and needs the passive antibody.

8:06Hepatitis E sits next to A in the fecal-oral category but diverges in two specific scenarios. The genotypes causing epidemic water-borne disease in south Asia and Africa transmit through contaminated water with the same acute pattern as hepatitis A, while the zoonotic genotypes have reservoirs in pigs, deer, boar, and shellfish, transmitting through undercooked pork and game, and the zoonotic form dominates hepatitis E in the US and Europe. The boards exploit this because hepatitis E is increasingly recognized as a cause of acute hepatitis in patients who don't fit a classic exposure profile, with a notable share of the population showing prior serologic exposure and a meaningful fraction of cases initially called drug-induced liver injury reclassified as hepatitis E once tested. So hepatitis E IgM belongs on the workup of any acute hepatitis where the conventional panel is negative and the case looks like drug injury without a convincing drug, and on any returning traveler with acute hepatitis. Two clinical scenarios are the high-yield ones, and both pivot on the host. The first is pregnancy: third-trimester acute hepatitis E with the epidemic genotypes carries an acute liver failure mortality of twenty to thirty percent, far higher than in nonpregnant patients with the same virus, making it one of the named viral causes of acute liver failure in pregnancy, probably from a combination of altered cellular immunity, hormonal effects on replication, and reduced regenerative capacity, and it also causes low birth weight and fetal loss, with no pregnancy-approved antiviral, so management is supportive with delivery planning when failure develops. The second is chronic hepatitis E, defined by persistent RNA beyond three to six months, occurring almost only in immunocompromised hosts, dominated by solid-organ transplant recipients, and producing progressive fibrosis toward cirrhosis if untreated, with the recognition cue being the transplant patient with persistent unexplained transaminase elevation and a negative standard workup. Diagnosis in the immunocompromised host requires the RNA, not just the IgM, because immunosuppression blunts the antibody, so an antibody-negative transplant patient can still carry replicating virus.

10:12Treatment of hepatitis E follows the host: the immunocompetent acute case and the pregnant patient are supportive, and chronic infection in the immunocompromised is treated first by reducing immunosuppression when feasible, which clears the virus in about a third, and when that fails or isn't feasible, ribavirin for three months is the treatment of choice with a high response rate, with interferon a second-line option in selected liver transplant recipients but avoided in other organ recipients for rejection risk. So the recognition cues tie it together: the returning traveler with acute hepatitis and a negative conventional panel gets hepatitis E IgM; the third-trimester pregnant woman with acute hepatitis and rising INR is the high-mortality scenario in the epidemic-genotype regions; the transplant recipient with unexplained chronic transaminase elevation gets the RNA, not just the IgM; the apparent drug injury without a drug gets hepatitis E IgM; and any chronic liver disease patient unvaccinated against hepatitis A gets the vaccine.

11:07So pull it together. Acute viral hepatitis is read off the panel, not the symptoms, because the clinical envelope is the same across viruses, with the phases running incubation, prodrome, icteric, and convalescent, and anicteric presentation the rule in immunocompetent adult hepatitis B. The serology rules are precise, with two named traps, the hepatitis C antibody lagging viremia by a couple of months and the hepatitis B core IgM repositivating during a chronic flare. And the fecal-oral viruses are largely self-limited but each has a named high-risk scenario: hepatitis A in older adults and chronic liver disease can fulminate, which is why post-exposure prophylaxis splits by age and host, and hepatitis E in third-trimester pregnancy kills at twenty to thirty percent while chronifying in transplant recipients and responding to ribavirin once immunosuppression reduction fails.

11:59The next episode is hepatitis B, where the panel becomes a grid: the serology across surface antigen, core antibody, surface antibody, e-antigen, e-antibody, and viral DNA; treatment by phase with the nucleoside analogs; vertical transmission prevention with maternal tenofovir late in pregnancy plus infant immunoglobulin and vaccine; reactivation prophylaxis during immunosuppression; and hepatitis D coinfection with the new entry inhibitor.

12:28For the full chapter, the practice vignettes, and the topic-tagged question bank, head to board pearls dot com. You'll find the rest of the series on Apple Podcasts, Spotify, or wherever you listen to podcasts. That brings us to the end of episode one of three of chapter eighteen, and I'll see you in the next one.