Measles Virus – Paramyxoviruses

00:01 So, let's look first at measles virus.

00:03 This is a very, unfortunately, increasingly common virus in parts of the world where there are populations that are under vaccinated, currently, in the States and other parts of the world.

00:16 There's an incubation period of around 1-2 weeks, so 7-13 days, per the slide.

00:22 And after the initial infection of the upper respiratory tract and localized lymph nodes, with a secondary viremia, one can have attack to all the areas which you see in the slide.

00:33 So, the conjunctiva, the urinary tract, the small blood vessels, lymphatic system, even throughout the central nervous system.

00:41 And how far the viremia spreads and how aggressive it is, meaning that the viral load, really accounts for how severe the symptoms of the accompanying measles actually are.

00:53 So, what does measles look like? First, there is a prodromal period, which is very nonspecific.

01:00 However it -- I mean, it starts with fevers, malaise, etc., and then the patients develop the classic 3 C's: cough, coryza, conjunctivitis.

01:12 The cough. It's a brassy, deep cough, almost like a smoker's cough, which sometimes is productive of a deep sputum.

01:20 The coryza is typically starting as clear and then it becomes even a mucopurulent nasal discharge.

01:27 And the conjunctivitis.

01:29 Erythematous injection of the full conjunctiva with a very copious tearing of the eyes.

01:36 And along with that, sort of a photo phobia.

01:39 So, it's at this time that the patient may mistakenly be thought to have something like adenovirus, a cause of pink eye, or even influenza So it's still despite the presence of the classic 3 C's, a nonspecific presentation.

01:57 If one has a clinical suspicion, and if so, I take my hat off to you because it's hard to make that clinical judgment, but if one does, on day 3 of this prodromal period, one can start to see Koplik spots inside the mouth.

02:13 And with the picture in front of you, the dark arrow is showing one of those.

02:18 Koplik spots are sort of bluish-gray, small, like maybe 1 millimeter in diameter, papules on the buccal mucosa that have a slight surrounding red halo.

02:29 They're easy to miss unless you're specifically looking for them.

02:33 And if you see the Koplik spots in the setting of the 3 C's we just talked about, you have made your clinical diagnosis of measles.

02:41 Isolate and go on about your business.

02:44 However, many times, those presentations are missed, and then a maculopapular rash which has been nicknamed a morbilliform rash, a measles rash, kind of like defining it by the name of the infection, which is not very helpful.

02:59 But a densely erythematous, maculopapular rash starts and the distribution and progression is very key here.

03:08 It starts up at the head, starts cranially, and it moves caudally toward the tail, as it were, toward the extremities.

03:15 But there is a clearing of the rash as it moves from section to section over the period of 3-4 days.

03:23 So, with, still present, a conjunctivitis and one can see this dense, maculopapular rash on the face.

03:33 And then as it moves down toward the trunk, it may start to clear on the face and the conjunctivae may start to clear up as well.

03:40 By the time we get down to the lower abdomen and the pelvis, the areas of the neck and above may be either completely cleared or pretty close.

03:48 So, the progression is key to a clinical diagnosis of measles.

03:54 Unfortunately, there's no treatment.

03:56 There is prevention, as we'll talk about shortly.

03:59 But regardless of, you know, how severely ill or not severely ill the patient is, there are still complications.

04:08 These patients can progress to serious or severe measles, with pneumonia, These patients can progress to serious or severe measles, with pneumonia, with encephalitis, with seizures, with coma, the whole 9 yards.

04:18 And then after they've recovered from this spontaneously, and it may take several weeks for that, they are at risk for developing SSPE, subacute sclerosing panencephalitis.

04:30 This is a nasty.

04:31 This is very much, in appearance, like Alzheimer's disease, but it progresses, from start to finish, over a period of maybe months to at most, years, 1-2 years.

04:43 So think of these patients as losing cognition, losing awareness, losing body function, etc., but very, very rapidly.

04:52 So this is horrible.

04:53 And, of course, the whole thing is preventable via vaccine.

04:57 How to make the diagnosis.

04:59 Well, as mentioned, there -- I've given you multiple clinical clues.

05:02 The three C's: a progressive rash with clearing as one goes to the caudal region, and then, of course, the appearance of the rash itself.

05:12 But once one has a clinical suspicion, molecular diagnosis currently is the best way to go.

05:18 So an RT-PCR will pick up the RNA of the virus itself.

05:25 Transmission, as mentioned before, as with the other viruses, it's respiratory droplets.

05:30 Patients can be contagious prior to the onset of symptoms, prior to that prodrome, unfortunately, so during the incubation period of 1-2 weeks, patients can be infectious.

05:41 Which is unfortunate because it allows for epidemics or outbreaks of the disease to occur if one has a unvaccinated or under vaccinated population.

05:52 So, prevention, that vaccine.

05:55 Very effective.

05:56 A live, attenuated vaccine which we start to give to infants at 12-15 months of life with the booster at 4-5 years of life.

06:04 Currently, the vaccine is part of a combination vaccine, the MMR: measles, mumps, rubella, and all 3 are live and attenuated.

06:13 For patients who are unvaccinated, under vaccinated, maybe have only received 1 vaccine, or their vaccine status is unknown, if they are exposed to, in an epidemic setting, , a known case of measles, they can be given measles immunoglobulin.

06:31 So passive immunization to help them be protected, at least, for several weeks against developing further disease.