Erythema Migrans (Lyme Disease) and Erythema Infectiosum (Fifth Disease)

00:01 Here we have erythema migrans.

00:03 We want to make sure that you take a second and you take a look at this picture and it’s like you’re taking a dart and you’re practicing -- dartboard.

00:14 In other words, you’re going after the target.

00:17 This is a target lesion.

00:20 What happened? If you go right – Take a look at this a little bit closer.

00:22 I want you to go into the middle of the target.

00:25 That’s where the Ixodes tick burrowed, right? Deep inside.

00:30 And when it did, it then elicited or introduced a bacteria or spirochete called Borrelia burgdorferi.

00:37 Welcome to Lyme disease.

00:39 All right, so erythema migrans or erythema chronicum migrans, we call it a target lesion.

00:45 Pay attention to the description.

00:47 You have a central area of erythema.

00:50 Think about target.

00:51 Surrounded by pallor.

00:54 Then surrounded by a perimeter or ring of erythema.

00:58 And the cycle continues.

01:00 Target, target, target lesion.

01:02 It may be associated with fever and/or arthralgia caused by Borrelia burgdorferi.

01:07 The name of the tick is Ixodes.

01:08 Remember with Lyme disease, you’re up in northeast U.S., you were hunting deer per se, and you end up developing or acquiring the tick and then the bacteria.

01:19 Here’s my vector, the Ixodes scapularis.

01:24 Management: Doxycycline.

01:28 And we have fifth disease.

01:29 This is erythema infectiosum.

01:32 Make sure that you’re familiar with this.

01:34 Fever, coryza.

01:37 What ends up happening in terms of your history? It looks like there’s a slapped cheek.

01:43 Fifth disease, think of it that way.

01:44 Take your hand, which has five fingers, slap my cheek.

01:49 Slapped cheek-like appearance.

01:52 Lacy, reticular rash on extremity.

01:54 Take a look at this patient here and you’ll notice on the back, it's a lacy type of reticular – What does reticular mean? Networking.

02:03 Remember the reticular pattern that we saw on chest x-ray with interstitial lung disease? The same thing, but this time, we’re going to find this being erythematous.

02:12 Now, the cause is -- memorize parvovirus B19, a single stranded DNA.

02:19 No longer really infectious once the rash appears.

02:23 Pregnant women exposed are at risk of hydrops fetalis, unfortunately.

02:30 And may cause what’s known as your transient aplastic anemia.

02:34 Why? Because if you’re dealing a parvovirus B19, there’s every possibility that there is shutting down of your bone marrow, resulting in a normocytic type of aplastic or non-hemolytic type of anemia.

02:49 That, we’ll talked about plenty when we deal with parvovirus B19 with either sickle cell disease ands so forth.