Hepatitis A

00:01 Okay, let's go in order.

00:04 Hepatitis A is a single stranded RNA hepatovirus.

00:08 The transmission route is fecal-oral, doesn't sound very pleasant, but that's what it is, contaminated food or water that has come from feces.

00:19 Typically, in every case, it is a self limited to disease.

00:24 In most cases, it comes and goes in about two months, and it has a very low morbidity mortality, much less than 1%.

00:33 And when it does have mortality or morbidity, it's in the adult population.

00:39 There is no carrier state for all intensive purposes, almost everybody, virtually everyone who gets infected with hepatitis A will develop a good immune response to it and clear it.

00:51 New infections are characterized by having IgM against the hepatitis A virus or HIV.

00:58 If you've had a prior infection, a long time ago, or a couple months ago, then you will have IgG.

01:04 So that's one way that we can tell whether you have a brand new hepatitis A infection, or you've had one in the past.

01:11 Vaccines are available because it has such a low risk of causing mortality or morbidity.

01:18 And patients do really well with this.

01:21 Vaccines are not typically administered.

01:25 This schematic we're gonna see in some form over and over again, for all five of the different hepatitis viruses.

01:32 And this is just showing you from the point of infection, which is always going to be times zero, through the subsequent course, when the various manifestations occur.

01:44 So for example, in Hepatitis A infection, we can detect relatively early on RNA, either in the feces or in the serum indicating that we have an active infection.

01:56 That amount of virus actually precedes any injury to the hepatocytes.

02:01 That's when we see a relative spike in ALT and AST and other enzymes that the hepatocytes normally make.

02:10 That will be transient over the course of maybe a month or more.

02:15 That goes up and comes down as the body makes a specific immune response.

02:19 And it begins with a T-cell response, but then it's also coordinated with development of IgM antibodies, and eventually a maturation of the response to give you a chronic IgG serology.

02:32 So that you will have now chronic protection forever and ever and ever, to any subsequent exposure in Hepatitis A.