[ad_1]
IIf you live in Massachusetts or Michigan, you probably hear a lot about something called EEE. Otherwise, this combination of vowels can cause you to draw a blank.
But 2019 turns out to be a big year for Eastern Equine Encephalitis, commonly referred to as EEE – "triple E" – for short. And if he has not reached your radar yet, he will probably do it.
We think you will have questions. We have collected some answers.
publicity
What is the EEE?
Eastern equine encephalitis is one of the New World encephalitis viruses. This is also what is called an arbovirus – virus transmitted by a mosquito or other arthropod. West Nile is another type of arbovirus.
The virus is present in the northeastern part of the country as well as along the Great Lakes and the Gulf Coast. It is also occasionally found in Canada; At least one human case was reported in Ontario in 2016.
What kind of disease does this cause?
In a word: severe.
In fact, some people have mild influenza illness when they get the infection, said Marc Fischer, an epidemiologist at the Center for Arbovirus Disease Control and Prevention, located in Fort Collins, Colorado.
But about 20% of infected people develop a clinical disease and about half of them develop a neuroinvasive disease – in which the virus infiltrates the brain and ignites it, triggering encephalitis .
This can start with the sudden onset of a headache, high fever, chills and vomiting, and lead to disorientation and seizures.
The mortality rate is high: about a third of EEE patients who develop encephalitis die. And severe EEE survivors often have lasting side effects, including mild to severe brain damage.
"This is the highest mortality of all arboviruses that occur in the United States," Fischer said.
What is the frequency of IAS?
This is the good news. This is not common at all.
"It's a serious disease … but the numbers are small and much smaller than for West Nile virus," Fischer said.
From 2009 to 2018, 21 states recorded 72 human EEE cases, reports the CDC. Most have had only one case during this decade; Florida (13), Massachusetts (10), New York (8), Michigan and North Carolina (7) and Georgia (6) are the only states to have recorded more than a handful of cases during this period.
According to the CDC, the United States experiences an average of seven cases per year, with the standard deviation varying between three and 15 cases per year.
This is much less common than cases of West Nile virus, which are usually hundreds each year. To date this year, 468 cases of West Nile virus have been reported to the CDC, including 21 deaths – and this is not a particularly bad year for West Nile.
But that seems like a bad year for the EEA, is not it? Why?
So far this year, six states have notified 20 EEE cases. Massachusetts – a historic hotspot for the virus – has recorded nine cases and Michigan, seven. Other states that have experienced cases in 2019 are New Jersey, North Carolina, Rhode Island and Connecticut.
Six of the infected people have died so far.
There were 21 cases in 2005, which is therefore not completely irrelevant, but 2019 announces it as a very active EEE year, said Scott Weaver, an expert in arbovirus from the medical branch of the University of Texas at Galveston.
"I guess what's a bit worrisome is that we're already at the upper limit of the normal range and we're still only in mid-September," Weaver said. directs the Department of Microbiology and Immunology of the UTMB. "In Massachusetts and other areas of the northeastern and central Atlantic, we may have another month or more of active transmission and other future cases."
Some years are more active than others in this type of virus, Fischer explained.
"Every few years, you receive a higher number of cases. And they can be in different places. Massachusetts is one of the states that has always had the highest number of cases. But there are other states. Florida usually has the largest number of cases, "said Fischer. "So, it moves, it happens in different places and different years. And you have high and low years.
The reasons for this are not entirely clear, but they are certainly influenced by the complicated life cycle of EEE.
What is the life cycle of the virus?
If you know anything about West Nile virus, it will sound familiar to you. The virus infects mosquitoes, which feed on birds, which infects them. This is called an amplification cycle: uninfected mosquitoes that feed on infected birds become infected themselves, accumulating more and more viruses in a given area.
With EEE, the mosquitoes involved in this cycle call Culiseta melanura, who live in freshwater swamps and feed on songbirds. These mosquitoes are thought to feed almost exclusively on birds.
At some point – usually starting in July – there is enough virus in mosquitoes and birds in one place that spreads to other populations. Different types of mosquitoes – some Culex mosquitoes that can transmit West Nile virus, for example – feed on infected birds and catch the virus. These different mosquitoes, called bridging vectors, can then attract other species such as man in the EEE web.
Once an area has experienced a hard freeze, mosquito activity decreases and the virus actually goes dormant until the following spring. According to Weaver, along the coast of the Gulf of Mexico, where jellies are rare, human cases can occur at any time of the year.
Why more fallout occurs some years than others is not certain.
Climatic conditions probably play a role. A mild winter, for example, could allow the amplification cycle to start faster, producing more viruses in the environment, Weaver said.
Many studies on the life cycle of the virus are decades old and may not fully reflect current circumstances.
"Much of our understanding of the basic cycle of enzootic transmission comes from work done more than 60 years ago," Weaver said. "And there have been very few field-focused projects on this avian cycle for several decades."
When the EEE escapes the mosquito-songbird cycle, which species does it infect?
The second E of EEE is a clue. The first outbreaks of equine encephalitis in the East actually occurred in the 1800s in horses – long before the cause of the disease was discovered in 1930.
The deer also contracts the virus, as sometimes dogs do. But these other animals, like humans, are considered impassable hosts in the transmission cycle of IAS. We do not contribute to its spread.
The virus is very dangerous for horses and these can and should be vaccinated in places where we know that the EEE is spreading.
If horses can be vaccinated against EEE, can people?
Unless you are a student researcher in EEE. Weaver and other scientists studying this dangerous virus have been vaccinated with an unregistered vaccine developed by US military laboratories, but it is not accessible to the general public.
Several experimental EEE vaccines for people have reached the preliminary stages of development, but as the cases are so rare, there is no human market for the EEE vaccine. Given the very high cost of developing, testing and licensing a vaccine – under $ 1 billion – without a market, there is no chance of creating a vaccine .
Arbovirus expert Darci Smith, head of the Immunodiagnostics Department at the Naval Medical Research Center in Fort Detrick, Maryland, spoke about West Nile virus.
When West Nile was first discovered in North America in 1999, the situation was very worrying. And in a number of years since, there have been thousands of cases. Like EEE, West Nile can cause serious illness and death. In fact, he killed more than 2,000 Americans between 1999 and 2016.
Sanofi (SNY) Pasteur began developing a vaccine against West Nile, but eventually put the project on hold after concluding that there were not enough cases or that the public interest in securing sales was sufficient. Pharmaceutical companies do not do what they can not sell.
"And there is still no license [West Nile] vaccine, "said Smith.
If there is no commercial prospect for a vaccine, why does the EEE vaccine continue?
The Ministry of Defense considers EEE as a potential threat to biological weapons, due to the seriousness of the disease and its high mortality rate.
But for the Pentagon's interest, there would be little research on the EEA, said Weaver and others.
[ad_2]
Source link