West Nile Virus - Virology, Transmission, Symptoms, Diagnosis, Treatment, Prevention, Current Events

Introduction, Monkey Pox, Mosquito Borne Illness Overview hey everybody and welcome back to another video here at whiteboard medicine it has been too long I hope everybody has enjoyed their summer thus far uh today we're going to be talking about West Nile Virus and this was the people have spoken so if we pull up our YouTube channel here and we go to community we uh put a poll out about a week ago asking uh we're going to ramp back up what topic do you want us to cover next and you can see West is virus and monkey pox were neck and neck at the 42% each so we're to start with West Nile Virus but we think that since there was a tie we probably will have to cover monkey pox as well I did just want to do a shout out if you search whiteboard medicine monkey pox we actually put out a video on monkey pox uh this was during the first monkey pox outbreak about two years ago so there's a lot in here just about monkey pox and the disease in general General that's very applicable um to what is going on right now uh but it certainly doesn't have the updates on the current spread of monkey pox which we'll probably come up with an update video but if you're interested in learning more about monkey poxes uh in the YouTube search whiteboard medicine monkey pox and that'll pop up uh today though we're going to be talking about West Nile Virus as a secondary reminder uh we did put out a video on mosquito season what you should know uh that was actually last year and in this video we talk about a lot about mosquito born illnesses in general mosquito anatomy life cycle myth busting how mosquito spread disease disease case counts etc etc we'll link this in this video description if you want just some general overview of mosquito born illness in general um because today we're going to dive into the specifics of West Nile virus itself we're going to start with the virology of westnile virus we'll talk about how it's transmitted the signs and symptoms the diagnosis treatment prevention and then at the end we will go into the current state of things uh but we're going to start with some of the general introductory stuff we will put timestamps in this video's description if you want to skip around uh no further Ado 30 second break for the introduction then we'll hey everybody and welcome to whiteboard medicine we appreciate you checking out the video here at whiteboard medicine our goal is to create medical education content for all types of interested Learners that includes videos practice questions study resources and much more we would love for you to join our community by subscribing hit that Bell button we're also working to build a high yield patreon page it's going to be full of practice questions video outlines notes commercial free content and much more none of these videos are intended to be acted upon as medical advice please pause the video here and read this disclaimer its entirety before moving on all right thanks for sticking around so Virology, Flaviviridae Family, Arboviruses West Nile Virus a little bit of an introduction to West Nile Virus um this is a mosquito born illness um and we are talking of it today because it has been spreading throughout the USA um but this is an international disease that's called West Nile Virus because it was first identified west of the Nile so there's many countries that get West Nile Virus and westn virus disease um currently there's an outbreak in the USA that is what is closest to us here at whiteboard medicine because we live in the USA um but certainly there are other countries and other continents struggling with West Nile Virus as well in the US it's primarily a summer and fall uh illness obviously it's mosquito born so it follows the life cycle of the mosquitoes and obviously in Winter mosquitoes are not present in biting people so it's a summer and Falls disease uh that's why it's big season right now and probably we'll get a little bit worse before it gets better there are no known vaccines to prevent West Nile Virus when it comes to w virus the disease itself of every five people that get the virus in their system only one in five will get ill and that one in five is about minor symptoms which we'll talk more about so obviously it's about 20% of people who get bit by a mosquito with westnile virus and get the virus in their bloodstream only about 20% of them actually get sick a much smaller number about one in 150 people get critically ill they get that neuroinvasive West Nile dis disease the severe disease that can be deadly uh so very few people of all those infected get this neuroinvasive deadly form West n virus although if you do certainly you can get very very sick so quick peek into the virology virology being what is the virus all right so for those interested and I'll go quick uh because it probably doesn't tickle the fancy of a lot of people but this is an enveloped singl stranded RNA virus what does that mean well if we peek over to the right here that means that the genetic material of the virus is a single strand of RNA ribonucleic acid that's in comparison to DNA uh deoxy ribonucleic acid so it's a single stranded RNA virus okay it also has an envelope meaning it has an outer coating that envelope does affect its kind of orology the way it behaves although we won't dive into it too much in this video uh itself it is part of the Flava verid family which is a larger family of viruses and you'll see it referred to as an AR virus an arbo virus just means that it is a virus that is transmitted by insect bites and in this case we talked about how it is mosquito bites that transmits this virus so it is an arbo virus which is kind of an umbrella term for all those viruses spread by insect bites Eastern acine and sephtis has gotten some news cycle as well that's spread by mosquitoes that would also be considered an arbo virus okay so transmission how can you get West Nile Virus well West Nile Virus is primarily a disease of mosquitoes and birds all right so this is a mosquito Transmission, Incubation Period, Birds, Humans, Mammals it's the species of mosquito most likely to transmit westnile virus is the clex species of mosquito and the life cycle of West Nile is mosquito to bird bird back to Mosquito right so the mosquito bites the bird if the bird is infected with West Nile Virus the mosquito sucks blood with West Nile Virus the virus gets into the mosquito system and travels to its salivary glands and then it goes and bites a different bird and some of that virus in the mosquito salivary glands gets inserted into the bird's bloodstream and causes the bird to have West Nile Virus it's been found in over 300 species of birds so lots of different birds can get this but it affects Birds differently certain birds can die from it okay birds like crows can commonly die from it other birds don't die from it so there's a variety of illness uh depending on the bird's species in addition to this birds can give it to themselves um so predator birds that eat other bird species if that bird is infected with West Nile virus and a bird eats that uh dead bird with West Nile Virus uh it can get the West Nile virus from the Dead Infected bird so eating infected birds can be a way from of birdt bird transmission unfortunately mosquitoes don't just bite Birds right they also go and bite humans so if a mosquito is infected and has the virus in its salivary glands then it goes and bites a human it can give that human West Nile Virus now humans are considered dead end hosts and what that means is that once it is in a human if a mosquito then bites that human with westal virus the human cannot I'm going to do a different color let's do red cannot give it back to the mosquito that can't happen and the reason being is because the viral load the amount of virus in the blood is not high enough so low viral load for the human the mosquito that bites the infected human to get enough virus to spread it to something else and that's why they're cons we're considered dead and host because we cannot give it back to a mosquito to then spread to others we can though give it to one another all right there is a human to human possibility of trans transmission this is very uncommon and the times we have seen it is with blood transfusions right so if you are infected and donate blood it's a very small chance but there is a chance that whoever receives that blood could get West Nile Virus they recommend not donating blood for about 120 days after you have gotten West Nile Virus they've seen it very uncommonly in organ transplant patients let's say you have West Nile Virus and then you donate an or organ the person that receives that organ has the possibility of getting westnile virus U mothers can transmit it in breast milk so if you are breastfeeding you get West Nile Virus you could transmit it through your breast milk to the baby and then very rarely um only a couple cases quoted transplacental meaning if the Mom is pregnant and gets West Nile Virus she could transmit that virus through her placenta into her baby uh but very uncommon not a lot of cases of any of these documented but certainly possible the other thing that people ask about is can we get it from birds and as far as we are aware no one has caught it from a bird not eating a bird or handling a bird now the CDC does recommend you wear gloves if you're handling a dead bird because there's a possibility of transmission here but there's been no known cases of person eating an infected bird or handling a dead bird that was infected and then getting the West Nile virus from the bird all right so mosquitoes give it to birds who give it back to m mosquitoes birds can give it to birds if they eat a dead and infected bird mosquitoes give it to humans but that's a dead and host humans cannot give it back to mosquitoes humans can give it to one another but very uncommon and we talked about the ways and then birds do not seem to be able to give it to humans um although there's a recommendation to wear gloves and handle dead birds with care and all that kind of stuff once you get the virus the incubation period the amount of time it takes before you start to show symptoms is about 3 to 14 days so a couple days up until about 2 weeks right so it's always good to know how long it can be in your system before it would manifest with any symptoms all right so that's the transmission of it Signs, Symptoms, Mild Disease, Neuroinvasive Disease well what are the signs and symptoms you know we said incubation period is 3 to 14 days what are the signs and symptoms well as we talked about above only one in five people um we uh phrase this wrong one in five people do not remain asymptomatic so only 20% of those infected have symptoms so 80% remain asymptomatic apologies for that typo hopefully it makes sense we're just going to State it again to be clear one in five people develop symptoms 80% of people infected remain asymptomatic okay and then 1 in 150 people developed the severe neuroinvasive disease so we divide this up into kind of two different titles West Nile fever this would be considered kind of the minor version of disease right and we said about 20% of people who get the westnile virus develop symptoms and those 20% develop this West Nile fever and this is kind of just generic viral syndrome symptoms right these kind of look like symptoms you'd get if you had the flu you get a fever you get a headache you get body aches or myalgia a little nausea vomiting and GI up set lymphadenopathy it means swollen lymph nodes okay so you can get swollen lymph nodes in your neck or you're groin and then a small percentage so a small percent of people uh can develop a rash although that's certainly not a large percent of people all right of those unlucky The Unlucky One in 150 of people who get westn virus can develop severe disease and this is that neuroinvasive westn virus this is the feared comp complication of West Nile Virus this is if you've seen people say menitis the meninges are the coding of the brain menitis is inflammation itis of the meninges in sephtis right this is in En sephtis is inflammation of the brain there's like maningo entis combining these two you can get inflammation in your spinal cord this is all neuroinvasive disease invading your neuros system your brain and spinal cord and here you get very sick high fevers neck stiffness or pain this is kind of a generic symptom of this menitis and sephtis right when you bend your neck your spinal cord goes from your brain in your head down your neck into your back right so if you're bending your neck it pulls on your spinal cord a little bit and if you have inflammation of those meninges or the coating it causes pain so you get neck stiffness neck pain neck rigidity you can get stuper or coma so altered mental status uh coma you can get seizures uh weakness arm leg both neither and it can go so far as paralysis you can get deep coma with paralysis and there's a fair amount of mortality with this patients get really really sick and they can have permanent uh neuro deficits they can even die from this disease so how do we diagnose it then Diagnostics, Labs, Lumbar Puncture (spinal tap), CSF Studies well the diagnosis can be really tough if you were to go to the hospital and get evaluated um and you had this West Nile fever version You' kind of just have these non-specific findings right you might have a little bit of an increased white blood cell count you know it's just generic kind of nonspecific inflammation or or reactive disease right you might be a little dehydrated if you're having nausea vomiting or decreased oral intake but you don't really have a lot of lab abnormalities if they were to get a CT of your head a cat skin of your head it most likely would be negative there's not good serum tests for the virus itself but if you were to get really sick and get the severe West Nile disease this neuroinvasive disease this is where you'd have to get a lum bar puncture a lumbar puncture is a spinal tap it's where you poke a needle in the lower back through the skin into the spinal canal and you get a sample of the cerebral spinal fluid the CSF cerebral spinal fluid and this cerebral spinal fluid you can test for West Nile Virus all right you can actually send a test off I believe there's both a PCR polymer Chain Reaction looks for protein and an imunoglobulin IGM if it is the imunoglobulin test there are false negatives we kind of wrote that right here um because immunoglobulines are produced by your B cells by your immune cells right so you got a B cell here when it comes across the virus let's say this is the West Nile Virus it has to take it into the cell produce antibodies right and then it has to secrete those antibodies out into the system and these are immunoglobulins or antibodies these could be IGM imunoglobulin but all that takes time right so they actually recommend in patients if it is an imunoglobulin test with high risk of disease that you re repeat the test in 10 days to make sure that you just didn't try to test for immunoglobulines too early all right for the P Chain Reaction looks for direct viral protein so that one picks it up more quickly you also might see signs in the cerebral spinal fluid pleocytosis meaning high white blood cells right white blood cells can suggest infection although they're very non-specific so high white blood cells in the spinal fluid for those interested in a little more details those will typically early on be neutrophils and later they would be lymphocytes two different types of immune cells neutrophils are part of what we call the innate immune system this is kind of the early warning system in the body whereas lymphocytes are more part of the Adaptive immune system which is uh after the innate immune system gets activated right when it comes across uh an Invader uh there's mechanisms that activate the Adaptive immune system so neutrophilia early lymphocytic later uh viral infections in general often lead to a normal glucose in the CSF so that's the sugar in the cerebral spinal fluid whereas if there's a bacteria this is a virus wesile virus if there's a bacteria let's say you had strepto coal menitis that glucose is usually low because those bacteria use up the glucose whereas viruses don't use up glucose and then usually there's an elevated protein in the CSF viruses are made of protein just like anything else so if there's a bunch of protein in the CSF it can cause an increased amount of protein in the CSF all right so there's no definitive way to diagnose West Nile Virus at least not at most hospitals unless you have neuroinvasive disease in which case you would need a lumbar puncture or a spinal tap and there could be kind of uh studies like the white blood cell count glucose protein that could be suggestive of it but what you would really need is this West Nile Virus test in the CSF a PCR or imunoglobulin test um to see if you have the neuroinvasive version of westnile virus all right so now we have diagnosed it what is the treatment this is Treatment, Supportive Care, Prevention probably going to be uh dissatisfying for people but the only treatment for neuroinvasive or non- neuroinvasive west virus is supportive care okay what that means is that there is no antiviral that can directly treat the virus supportive care is you know making sure the patient is hydrated with fluids if they have respiratory failure they might need to be on a ventilator you know make sure they have appropriate electrolytes nutrition and you support their body while their own body tries to fight off this infection this is why neuroinvasive disease can be so severe because there's no way for us to actually treat the virus itself all we can do is support the body while the body fights off the virus which then gets into the second question is well okay if I can't treat it how do I prevent it and another dissatisfying answer there's no easy way to prevent it there is no vaccine at least no available vaccine currently um to prevent West Nile Virus the only way to prevent it is to avoid those mosquitoes right so if you believe in uh mosquito spray or long sleeves and long pants at dusk um or avoiding going out when there's mosquitoes around preventing mosquito bites is the way you prevent this disease there's no other good way to prevent it all right that then gets into the Current Events, Case Counts, Spread current state of things why are we talking about this well there's if you just Google West Nile Virus there'll be a ton of news articles that'll pop up because it has been spreading this is uh in the US right as of September 3rd we're recording this on September the 5th uh and what you can see here is that in 2024 there's already been 377 cases of West Nile Virus unfortunately 255 of those have been that neuroinvasive disease and there's probably been more cases because one might look at those numbers and go 255 that's not one in 150 but there's probably been many more cases of West that we haven't detected right because the symptoms of just normal West Nile Virus are just kind of that generic viral syndrome so if you came to me and I was working at the hospital and you had you know a mild fever some aches I would probably test you for covid and flu and RSV and those easy things but there's no way for me to test you in your blood for West Nile Virus so I wouldn't do that I would just you know say you have a viral syndrome and give you good return precaution so there's probably a lot more cases than that 377 um which is why the neuroinvasive is 255 because the mass vast majority of cases we detect are going to be that neuroinvasive disease because in that patient they would get an LP as spinal tap and they'd get a direct test for the West Nile virus itself that would come back positive okay there's already been uh 38 states that have reported westnile virus and this is a map over here you can see this is westnile virus disease cases reported by state dark blue is greater than 25 this kind of light teal is one to five so you can see the big uh big places here that are reporting a lot of cases are California Texas you know really a a good number of the uh South what is that North southeast west southwest um some of the southeast and the Midwest are reporting a lot of cases there is some out east not a lot in the Pacific Northwest right all this is mosquito and climate related and if we want to get even uh more detail this is the total number of human infections by County the one thing to note though is interestingly they put here non-human activity so the light green the teal here is actually animals that have tested positive CU you can find West virus you can find it in horses dogs there's a whole bunch of different mammals obviously Birds um so these are nonhuman cases and the thing to note here is that humans are dead and host as we discussed right so where there are many animals infected you run the risk of human disease so you can see kind of in Illinois and Indiana here there's lots of animal cases and then in what seems to be kind of Chicago and Chicago land uh there's lots of human cases in California you see lots of human cases here with kind of this larger surrounding sphere sphere of teal which are animal cases same thing down in Texas you kind of get the center dark blue human cases with surrounding teal of animal cases um out in the Northeast you see a lot of animal cases right in Maine up here and then you kind of get the smaller sphere of human same thing in the rest of the Midwest uh human cases and animal cases so these two things go hand in hand as one might guess where there's animal cases there's going to be more human cases all right so there will probably be more information to come on this uh we're going into fall so there's still kind of prime time for the spread of West Nile Virus those in a high West Nile Virus endemic area certainly keep an eye on yourselves avoid mosquitoes long pants long sleeves bug spray all that kind of stuff as you see fit um and if you do start feeling sick or having any of these symptoms we talked about up here it'd be a reason to certainly go and get uh evaluated uh in the emergency department um because obviously if you get the severe version of the neuroinvasive disease uh no treatment just a supportive care as we talked about all right appreciate you all checking out the video let us know what thoughts comments questions you have down below keep your eyes period for the monkey pox episode and then we'll uh also do some of our uh classical kind of medical education uh videos moving forward as well so appreciate you stay well keep learning we'll see you next time