who is at risk of becoming ill from west nile virus? This is a topic that many people are looking for. newyorkcityvoices.org is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, newyorkcityvoices.org would like to introduce to you West Nile Virus (West Nile Encephalitis): Pathogenesis, Symptoms, Diagnosis, and Treatment. Following along are instructions in the video below:
Everyone welcome to another lesson in the system chocolate. The west no fire so we were going to talk about how we become infected with this virus. Were going to talk about signs and symptoms how we can diagnose it how we can treat it and how we can try to prevent becoming infected.
So the west nile virus is a virus in the viral family flavio verde. It is a flavivirus so its in the same family of viruses like dengue viruses. And it is also a member of the japanese encephalitis virus antigenic complex.
Were going to talk about the japanese encephalitis virus in another lesson like the other flaviviruses it is a positive sense single stranded rna virus and the west nile virus is important to understand because infection with this virus can cause encephalitis or inflammation of the brain. Were going to talk about this in more detail in the next couple of slides. And this virus is named after the place words.
First discovered. It was actually first discovered in the west nile province of uganda in 1937. So we can see here on the map.
Here is uganda and the west nile province is up in the northwest of the country and although. It was spread and cause infections in several countries for years. It became more recognized and talked about in the late 1990s and in fact in 1999.
It was introduced here united states and thats when we saw about sixty two cases of encephalitis and seven deaths in the united states in a virus is now considered endemic in north america. Which means that its not coming from other continents is actually here being transmitted through its vector and host. Were gonna talk about that in the next slide so how is it transmitted so the transmission of the west nile virus occurs primarily through birds.
So birds are the primary host for the west. Nile virus and the birds in particular are crows and blue jays. And what happens is theres a mosquito that comes around and bites and feeds on the bird.
That is carrying the virus. And when that mosquito picks up the virus from an infected bird. It becomes a vector and transmits the virus to other crows and blue jays transmitting and propagating the virus and we see this occurring with mosquitoes of the culex.
Species. And this is the reason. Why the west nile virus is known as an arbol virus.
And an arbol virus. Simply means. That it is a virus spread through arthropods.
So arthropods like insects like mosquitoes so an infected mosquito cannot only infect other birds. But it can actually bite and infect humans and this is why this is important in areas where there are bird deaths and where there is known west nile virus infections in blue jays and crows these mosquitoes can pick up the virus and transmit it to humans. And when a person becomes infected with the west nile virus or a mosquito bite.
That person can transmit the virus to other people and it occurs through vertical and horizontal transmission. So what is vertical transmission so vertical transmission is from one generation to another so from mother to fetus. So there is mother to fetus transmission.
That is possible in horizontal transmission. Is basically everything else so horizontal transmission. You can think of it through blood transfusions and organ transplants so you can theoretically take the blood out of an infected person and transfuse it into another person.
And you could infect another person that way or you could take an organ from an infected individual and transplant. It into an uninfected individual leading to an infection this can occur. But it is very very rare so now that we know how its transmitted.
What actually happens when a mosquito carrying the west umpires bites. A person so if a mosquito bites. An individual in that mosquito is carrying the virus that virus can enter into the persons tissues from the mosquitos saliva and the virus can then multiply in the skin of the individual.
That is called the early phase of infection eventually. What happens is the virus continues to multiply and enters into the blood stream. And that is what we call very mia virus in the blood and the virus not only enters the blood.
But it can also enter into regional lymph nodes and into the spleen. So the lymphatic system. And when it is in the lymph nodes in the spleen.
We call this the visceral organ dissemination phase and then in some cases very rarely but in some cases the virus can actually enter into the central nervous system into the brain and this is what we call the central nervous system phase. So individuals who are infected with the best known virus dont necessarily have to go through each of these phases. They dont have to necessarily go through all of these phases.
They might just make it into the early phase or into the visceral organ dissemination phase and a small subset a very small subset will enter into this phase. So what are some of the clinical features of the west nile virus. What happens.
When an individual becomes infected with this virus.
So theres an incubation period. That is roughly anywhere from 2 to 14 days so its quite variable. But whats important to recognize is that a majority of people that are infected with this virus are asymptomatic.
There is no symptoms in symptoms actually only occur in about 20 to 40 percent of infected people. So its actually a minority of people that have symptoms when they become infected with this virus. One of the big symptoms is fever.
So if they are to be symptomatic. Theyre likely to have a fever and we call this a west nile fever and this occurs in about a quarter of infected patients. So 25.
In for whatever reason. Women are more at risk for getting a fever in the west nile virus infection. Other symptoms include a headache.
Which usually occurs abruptly. So its an acute onset of a headache. We can also see my ologists or muscle aches and pains.
So these symptoms fever. Headache and mileages are very common among other viral infections as well. So there are nonspecific symptoms.
But we can also see back pain. In a west nile virus infection. Which is a bit more specific with regards to this viral infection.
We can also see anorexia. So they dont have much of an appetite and we can see a maculopapular rash. Which again is not very specific for west nile virus infections.
Other viral infections can lead to similar rashes in this maculopapular rash is non periodic. Which means that its not itchy and this seems to occur in about 25 to 50 percent of cases. Other clinical features of a west.
Nile virus. Infection. Include nausea vomiting and diarrhea.
So individuals can have gastrointestinal upset. With a west. Nile virus infection.
They can also have accompanying abdominal pain. And you can also have pharyngitis so a sore throat. So you can see here heres a pharynx that is quite red or irreligious so it can appear like an upper respiratory tract infection.
Whats very important to recognize with the west nile virus infection is that it can lead to neuro invasive disease and neuro invasive west nile disease so we mentioned before theres a central nervous system phase that can occur in some individuals and the neuro invasive disease with a west nile virus infection only occurs in very few individuals it occurs in about one in 150 to 250 people that are. Infected so its less than 1 or even less than 05. But when we do see neuro invasive west nile disease.
We can see encephalitis or meningitis. So encephalitis is itis information encephalo brain. So inflammation of the brain.
I mean enjoy encephalitis is inflammation of the brain and the meninges the layers that cover the brain. So what we see with encephalitis is we can see fever headache and altered mental status or confusion. So patient can be very feverish and very confused or have an altered mental status and in maninjau encephalitis.
We can see the same thing as encephalitis. But also signs of meningeal irritation or meningitis. So we can see signs like neck stiffness in brezinski sign and other signs of meningitis or meningeal irritation.
So please look up some of those signs if you want to learn more about those in with the neuro invasive west. Nile disease. We can also see acute flaccid paralysis.
So an abrupt onset of weakness and paralysis can occur with some of these patients. And we generally see the encephalitis. The min and jo encephalitis in acute flaccid paralysis that occurs more frequently in older patients.
Older patients need to be more at risk for getting these conditions. So. When i say older patients generally greater than the age of 60.
So here is a more in depth look at risk factors for the neuro invasive disease of west nile virus infections so number one as you mentioned before increasing age generally over the age of 60 number.
Two hematologic malignancies. So leukemias can lead to increased risk of having neuro invasive west. Nile disease infection from an organ transplant.
So we talked about that horizontal transmission as being a possible way that one person can infect another person. Its very rare. But it can happen and when it does happen it can be a higher risk of that patient having neuro invasive disease and number four is genetics.
So some people are just more at risk for getting the neural base of west nile disease for whatever reason. There are certain genes that are in play that actually lead to an increased risk and when a patient does have the neuro invasive west nile disease this is when the fatality rate increases dramatically and this is about an approximately 10 fatality rate. If a patient recovers from the west nile virus and even recovers from a neuro invasive west nile disease they can have post infectious symptoms.
So what that means is theyve cleared up all of their symptoms prior. But they can have issues later and we can generally see these symptoms in patients who had a neuro invasive west on the sea. So they can have persistent memory issues.
Persistent fatigue recurrent headaches. And even issues with their balance. That can last for a long time.
So how do we. Diagnose a west nile virus. Infection and how do we treat it so diagnosis of the west nile virus.
Infection is usually done through serology. So were looking for antibodies. So we want to look for a west.
Now igm antibody an important note is that there is cross reactivity from an igm to the japanese encephalitis virus. So they are a member of the same antigenic complex. So there is some cross reactivity.
So if an individual had the japanese encephalitis virus. They may look like theyre positive for the west. Nile virus.
Even though they might not be so. There is some cross reactivity to both of these viruses or the the antibody to both of these viruses. So if thats an issue pcr for viral genetics can be done.
Especially if its very very early on in the infection. If the person hasnt been able to develop the antibodies to the they can use pcr to detect the viral genetics. So once we make the diagnosis.
How do we treat. It treatment is supportive. This is a viral infection.
There are no specific treatments for the west nile virus. So a lot of times. We just treat them symptomatically.
So we treat their symptoms. And we support them through the recovery and they will recover spontaneously. The majority of the time.
But whats better is to try to prevent being infected with it in the first place unfortunately. There is no vaccine available against the west. Nile virus.
What we can do is what i like to call. Mosquito hygiene. And what is mosquito hygiene.
So mosquito hygiene essentially trying to prevent being bitten by a mosquito. So what we can do is we can try to wear a long sleeve clothes try to cover as much skin as possible. We can also use insect repellent to avoid or repel mosquitoes from actually biting you and we can use in certain areas mosquito nets.
So mosquito nets can be used when were sleeping outside to avoid being bitten by mosquitoes at night. So those are a few different ways we can try to prevent being bitten by mosquitoes and this is not a hundred percent guarantee that youre not going to become infected. But it can help reduce the risk of becoming infected.
So the references that i used for this lesson are in the video description below so please check out those references. If you want to learn more information about the west nile virus and if you want to learn more about other infectious diseases please check out my infectious disease playlist i have many topics in that playlist and if you havent already please consider liking subscribing and clicking the notification bubble. Help support the channel and say up to date on future lessons thanks much watching and continue to live laugh and learn.
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