CDC chart describing the major symptoms of Zika Virus in adults. (CDC.gov)
It has been a while since I have posted about Zika Virus. As the US mosquito season is peaking currently, I felt it would be appropriate to do so. Here are some important updates, based on some news articles I noticed in the past week:
Currently in the USA, the overall Zika Virus incidence rate is much lower than it was last year. In New York for example, the current infection level is approximately 55% lower than last year at this time.
In Central and South America, many countries are seeing a decline in Zika infections, however there are no countries where Zika Virus is disappearing. Interestingly, Argentina and Peru are seeing Zika levels increasing lately.
It is likely that the broad declines in Zika infections within the Americas are due to an increase in the natural immunity to the virus throughout the population. Once someone has been infected with Zika once, they cannot be infected again and cannot pass the virus onto other mosquitos. These mechanisms help decrease the spread and infectivity of Zika Virus.
Due to the sexual transmission of Zika Virus, the US government has amended their guidelines to inform Americans who have been exposed to Zika. Currently, women who have Zika symptoms should wait approximately 8 weeks before attempting to get pregnant. Men, however, should wait approximately 6 months before engaging in sex. The differences in time are due to Zika surviving longer in the testes than initially expected. (For a review of the symptoms of Zika Virus in adults, please see the graphic at the top of this post!)
On the research front, scientists have created a mouse model to study Zika virus’ life cycle and transmission characteristics. Creating this research model is a great advancement as it will allow scientists to gain more knowledge on the virus and allow us to make advancements in the prevention of its spread and treatment.
While Zika is currently less talked about than it was last year, it is still prevalent and should not be forgotten. I’ll post more updates as the news behind Zika Virus develops.
Yesterday afternoon, officials at the Centers for Disease Control (CDC) issued an alert for travelers heading to parts of Brazil. According to the official alert, officials in Brazil’s Ministry of Health have stated that there is an ongoing Yellow Fever outbreak that started in December of 2016. Initially in the Minas Gerais state, cases are now being seen in Sao Paulo and other surrounding areas. It is estimated that over 400 individuals have been infected thus far, with 40 confirmed deaths in humans and possibly 400 deaths in certain species of native monkeys. In an effort to fight back against the spread of this disease, Brazilian authorities are launching a widespread vaccination campaign to help immunize those who are currently unprotected. The CDC recommends that those traveling to effected areas of Brazil get vaccinated against yellow fever, or receive a booster if their last vaccination was over 10 years ago. Currently, there is a shortage of yellow fever vaccine, so getting vaccinated may take longer than usual.
Map of the Brazilian state of Minas Gerais, initial site of the current yellow fever outbreak. Brazilian officials are beginning to see yellow fever cases in neighboring Sao Paulo (v-brazil.com)
Here are some facts about Yellow Fever to help keep you informed:
The Yellow Fever Virus (YFV) is an RNA virus of the genus Flavivirus – the same family of viruses that includes Dengue and Zika Virus
Yellow Fever is commonly found in South America and Africa
As with many other diseases, yellow fever virus is a vector-borne disease that is spread through the bite of an infected mosquito, either the Aedes or Haemagogus The virus can be spread to other humans if a mosquito bites an infected human and transfer virus with it while taking a blood meal.
Most individuals who become infected with yellow fever will experience no symptoms or mild symptoms. For individuals who do experience symptoms, it usually takes between 3-6 days for them to appear after being infected. Common symptoms include:
Nausea / vomiting
General weakness and fatigue
In some cases (15%), the disease takes a severe course and includes symptoms such as high fever, jaundice, bleeding, shock, and possibly, death.
There is no treatment for yellow fever, so hospitalized patients will receive general supportive care until the disease works its way out of the body
How to minimize your risk of contracting yellow fever:
Get vaccinated!! Unlike other diseases in its family, the yellow fever virus vaccine is very effective at inducing immunity and does not require a booster in most cases. If you live in or are traveling to a region where yellow fever has been known to transmit, getting vaccinated is one of the best ways to remain safe
Use mosquito repellent – repellents containing DEET, picaridin and oil of lemon eucalyptus have been proven to work the best
Wear appropriate clothing – long sleeve tops and long pants are most effective at minimizing the amount of exposed skin that a mosquito could bite
Avoid going outside at dusk and dawn – mosquitoes are most active during these times, so avoiding them will help minimize your risk of being bit
The Aedes mosquito, one of the species of mosquito that is involved in the transmission of yellow fever (bbc.com)
When thinking about what to write this week, I was torn with what to write about. One of my classmates suggested that I write about Chikungunya, as she knows it affects many Caribbean countries. Looking into Chikungunya, I also see that this disease ties in nicely with the diseases I have already blogged about because, similar to Zika, it is transmissible via mosquitos. Below, I will talk about some of the major facts about Chikungunya, and describe how it is affecting the world today…
Chikungunya is a viral disease that was first noticed in Tanzania in 1952. When the first cases came in, this disease got its name based on one of the major symptoms that it causes. In the Kimakonde language, Chikungunya is derived from a word that means “to become distorted,” referring to the appearance of many patients.
Chikungunya is transmitted by mosquitos, primarily the Aedes aeqypti and Aedes albopictus Interestingly, these two species are also famous for transmitting other mosquito-based diseases, such as Dengue and Zika. Once bitten by an infected mosquito, Chikungunya symptoms can set in within 4-8 days.
The major symptoms of Chikungunya include a sudden fever with severe joint pain. In most cases, the joint pain disappears after a few days to a week, but sometimes this pain can last several months or years. Other symptoms include nausea, fatigue, muscle aches, and headaches.
Chikungunya is difficult to diagnose based on symptoms alone, but simple blood tests can quickly and easily confirm the diagnosis.
Unfortunately, there are currently no antiviral drugs to fight Chikungunya. When patients are identified, treatment is usually targeted at relieving symptoms. Fever and joint pain are commonly treated using standard treatments. The virus is usually cleared by the body within a week or two, but sometimes it can remain for longer.
The best way to prevent yourself from contracting Chikungunya if you are traveling to a region with high Chikungunya levels is to take efforts to prevent mosquito bites. Wearing long-sleeve shirts, pants, and mosquito repellents are internationally accepted standards to prevent mosquito bites. In addition, using mosquito nets, or ensuring that mosquito screens are installed in any room you stay in are also effective ways to minimize your contact with mosquitos.
Currently, Chikungunya is afflicting over 60 countries worldwide.
Where Chikungunya transmission is present, as of October 2015 (CDC.gov)
So, it’s been a while since I first wrote about Zika Virus… Today, almost every major news outlet carried the story that the Deputy Director of the CDC publicly stated that “Zika is scarier than we initially thought.” Today alone, I noticed this quote on the front pages of many news apps and papers. Given the fear that this headline easily instills in others, I figured this would be the perfect time to break down the facts of Zika, as it is currently understood.
Since my last Zika post, it has been shown that Zika Virus can be transmitted sexually, with 7 confirmed cases in the US mainland resulting from this.
Zika Virus is actively spreading throughout most of South America, all of Central America, and is beginning to spread through North America, including 30 states in the US.
Caribbean islands, especially Puerto Rico, are predicted to have a large increase in their number of Zika cases in the near future as we head into the summer months and there is increased interactions between mosquitos and humans
The CDC is warning women who are pregnant, or who are considering becoming pregnant in the near future, to avoid traveling to regions of the world where Zika Virus is actively transmitting.
Zika virus has been linked to an increase in the rates of microcephaly, particularly in Brazil, however not all pregnant women who contract Zika Virus will give birth to babies with deformities
It is possible that Zika Virus is associated with an increase rate of other birth defects, including vision problems, auditory deficits, and abnormal growth
As with many diseases, if you are infected with Zika Virus and the body fights off the infection, there is little to no risk that you will contract the virus again given your body’s immune response and memory
The White House, as recommended by the CDC, is diverting $589 million dollars in funding that was earmarked for Ebola prevention to promote research into the Zika Virus
Map showing the countries where Zika is actively transmitting, as of April 12, 2016 (CDC.gov)
There is still much to learn about Zika Virus and the research community is examining new ways to study, diagnose, and treat Zika Virus. As more developments arise, I will definitely post more updates to keep you informed! Thanks for reading my blog, and please let me know if you have any questions or comments about any of the diseases I have talked about so far. If you have suggestions for other diseases for me to talk about, please comment them below!
The Ebola Virus, as viewed under a microscope (CDC.gov)
While the Zika outbreak has captured much of the attention of the news, there is some important news that just released on the Ebola outbreak that occurred last year. On February 19, 2016, a major change occurred in the United States’ response to the Ebola crisis. The Department of Homeland Security decided to end its enhanced screening procedures for those who were arriving in the United States from countries in Africa that experienced the Ebola epidemic. The screenings included temperature checks at five of the major international airports in the country, including JFK, Newark, Dulles, Chicago, and Atlanta. This decision was made after the World Health Organization declared that the Ebola outbreak was over. It has been more than 42 days since the last known Ebola patient recovered, marking a period twice as long as the incubation period of the disease.
For now, it looks like the Ebola crisis has ended. In my next post, I will discuss where Ebola came from, and what we are doing to prevent an outbreak like this from occurring again in the future.
One of the most common problems noticed when a new disease emerges and the scientific community races to study it is the problem of under reporting. Under reporting in disease research can be seen at the case-reporting level (when local doctors incorrectly diagnose a disease and do not alert the proper authorities) or at a larger level, where whole countries do not properly understand and report the prevalence with a disease.
Under reporting can have serious consequences in infectious disease research because when scientists need to understand the severity of a disease, they will be unable to get an accurate and true picture. In the current Zika Virus outbreak in South America, one of the major problems being seen is the lack of accurate records as to the prevalence of microcephaly in children before the Zika outbreak. Scientists want to examine if there truly are more cases of microcephaly now than before, but the lack of records is proving to make the task difficult to complete.
Another example of where under reporting is proving to be a problem is in the study of Melioidosis, also known as Whitmore’s disease. Many people have never heard of this disease, (I haven’t heard of it before writing this post!!) but it is one of the most prevalent diseases spreading through many developing nations, such as India, Brazil, and other tropical areas. Melioidosis is caused by a shape-changing bacteria in contaminated soil and water, and it can infect both humans and animals. A new study, published in Nature Microbiology, estimates that this disease is under reported in 45 countries where it is known to exist, and is present in 34 more countries that do not report it yet. This is a serious problem because Melioidosis can be fatal within 48 hours of symptoms occurring. In these developing nations, where access to healthcare is limited and people live very close to one-another, this under reported disease can cause a serious problem in the future.
When you turn on your TV or open a news app on your phone, you are surrounded by talks about the Zika Virus. While the news focuses on Zika Virus as it is spreading through the Americas, little is being reported on its history in the world. Earlier this week, an article written by Jon Cohen was published in Science that briefly traces the history of Zika virus from when it was first discovered to the present day. Below, I will present an overview of some of the main historical facts presented in the article to set the stage for more posts about Zika in the weeks ahead…
The first reports of Zika Virus occurred in April of 1947 from a group of scientists studying yellow fever in the Zika Forest in Uganda. These scientists observed a rhesus monkey with an abnormal fever. At the time, they were unsure what the virus was. The virus was isolated and injected into mice to check for the possibility of transmission.
A few months later, the same scientists discovered the same virus infecting the Aedes africanus Again, this virus was checked for transmission and it matched the virus isolated from the rhesus monkey. The scientists named it Zika Virus, after the Zika Forest that it was discovered in.
One of the first scientists to examine Zika Virus’ mechanism of transmission was William Bearcroft. Bearcroft injected himself with isolated Zika Virus and waited until he had symptoms of the disease – headaches and a slight fever. Once he noticed symptoms, Bearcroft allowed female Aedes aegypti mosquitoes to bite his left arm. He took these mosquitoes to healthy mice, allowed them to bite the mice, and later observed the symptoms of Zika in the mice. This simple experiment confirmed that Zika Virus is transmitted by mosquitoes to humans and other organisms.
Since these initial discoveries, Zika has not been extensively studied, as other, more pressing and emergent diseases came to light
The latest outbreak, currently occurring, is the largest recorded Zika outbreak. Due to the greater number of infected individuals, scientists will be able to study the virus more accurately and in greater detail.
In today’s outbreak, many news articles are detailing the correlation of Zika Virus and increased rates of microcephaly (abnormally small heads) in newborns in countries such as Brazil. While this at first sounds terrifying, it is important to realize that there is no proven link between the two observations, and it is currently only a possibility. The CDC has published a study detailing how there maybe an association between Zika Virus and Microcephaly, but cautioned that prior to the Zika Virus fear, newborn head sizes were not recorded as accurately in many regions of Brazil, meaning that cases of microcephaly prior to Zika’s appearance could have slipped past the statistics. Currently, only 270 cases of suspected microcephaly have been confirmed, from the initial, newly identified 4,180 cases. Of these 270 newborns, only six were found to have the Zika Virus inside of them. It is important for this message to get out to the general public so fear and panic does not set in. While we do not know much about Zika Virus yet, it is important for the scientific community, the news media, and the general public to hold out on passing judgement until claims are proven.
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