Stay prepared and protected against Yellow Fever by being aware of its symptoms, getting vaccinated, and learning more about the disease today. Don't be caught off guard.

Yellow Fever

Humza Khizer

Overview

Yellow fever is a viral disease transmitted to humans through the bite of infected mosquitoes and characterized by fever, <a href="https://merisehat.pk/disease/jaundice-65">jaundice</a>, and muscle pain. 
&nbsp;

According to the World Health Organization (WHO), yellow fever is a serious public health problem in Africa and South America, where it is endemic<a href="#accordion">[1]</a>. The disease affects an estimated 200,000 people globally each year and causes 30,000 deaths per year<a href="#accordion">[3]</a>. About 90% of these cases and deaths occur in Africa<a href="#accordion">[3]</a>.

The disease is characterized by fever, muscle pain, and jaundice (yellowing of the skin and eyes), and can range from a mild flu-like illness to a severe, fatal form called hemorrhagic yellow fever. It is transmitted through the bite of infected Aedes and Haemagogus mosquito species.

Yellow fever is endemic in tropical regions of Africa and South America. In Africa, yellow fever is endemic in 34 countries, while 13 countries in Central and South America are endemic to yellow fever<a href="#accordion">[1]</a>. In 2013, Africa reported 84,000-170,000 severe cases and 29,000-60,000 deaths from the disease<a href="#accordion">[1]</a>.

Yellow fever outbreaks have also occurred in other parts of the world, including Asia and the Caribbean, but these are typically sporadic<a href="#accordion">[1]</a>. Transmission occurs when infected individuals travel from endemic regions to areas with high mosquito density and where people are unvaccinated against the disease. Aedes aegypti mosquitoes can then transmit the virus from person to person, leading to outbreaks.&nbsp;

Yellow fever has never been reported in Pakistan<a href="#accordion">[5]</a>. However, travelers from Pakistan who are planning to visit endemic regions may be required to show proof of vaccination against the disease. 
&nbsp;

There are no specific subtypes of yellow fever. 
&nbsp;

Signs and Symptoms

The signs and symptoms of yellow fever can range from mild to severe and typically develop within 3-6 days after infection. The disease occurs in three phases: infection, remission, and intoxication.

The initial symptoms of yellow fever are similar to those of other viral illnesses and can include:

<ul>
	<li>Fever and chills</li>
	<li>&nbsp;Headache</li>
	<li>Muscle pain</li>
	<li>Prominent backache</li>
	<li>Fatigue</li>
	<li><a href="https://merisehat.pk/disease/nausea">Nausea</a></li>
	<li>Vomiting</li>
	<li>Loss of appetite 
	&nbsp;</li>
</ul>

Next phase is the period of remission, when the individuals improve and may recover. It may last for 48 hours.

&nbsp;In 15%-25% of patients, a period of intoxication can occur where the symptoms recur<a href="#accordion">[6]</a>. This is a severe form of infection and approximately 30%-60% of individuals with the severe form die<a href="#accordion">[3]</a>.

The severe form, known as &quot;hemorrhagic fever&quot; is characterized by the following symptoms:

<ul>
	<li>Jaundice</li>
	<li>Abdominal pain</li>
	<li>Vomiting blood</li>
	<li>Dark urine</li>
	<li><a href="https://merisehat.pk/disease/bradycardia-slow-heart-rate">Bradycardia (slow heart rate)</a></li>
	<li>Petechiae</li>
	<li>Hepatomegaly</li>
	<li>Bleeding from the mouth, nose, eyes, or stomach</li>
	<li>Organ failure</li>
	<li><a href="https://merisehat.pk/disease/absence-seizures">Seizures</a></li>
	<li>Coma 
	&nbsp;</li>
</ul>

Causes

Yellow fever is caused by a virus called the yellow fever virus, which belongs to the Flaviviridae family. The virus is transmitted to humans through the bite of infected mosquitoes, primarily the Aedes and Haemagogus species. The virus is typically found in tropical and subtropical regions of Africa and South America, where it is maintained in a cycle between mosquitoes and non-human primates. When a mosquito bites an infected primate, it becomes infected with the virus and can then transmit the virus to humans through subsequent bites.

Infected humans can introduce the virus in populations where people have little to no immunity against the disease and a high density of Aedes aegypti mosquitoes. Infected mosquitoes can then transmit the virus from person to person<a href="#accordion">[1]</a>. 
&nbsp;

Diagnosis

The diagnosis of yellow fever is typically based on a combination of clinical symptoms and laboratory tests.

The gold standard for diagnosing yellow fever is a laboratory test that detects the virus or antibodies against the virus in the blood. However, these tests are not widely available in endemic areas and can take several days to produce results. 
&nbsp;

In order to quickly identify and contain outbreaks of yellow fever, rapid diagnostic tests have been developed that can provide results within 30 minutes. The most commonly used rapid diagnostic test is the IgM-capture enzyme-linked immunosorbent assay (ELISA), which detects IgM antibodies against the yellow fever virus in the blood. Another rapid diagnostic test is the polymerase chain reaction (PCR) test. It detects the genetic material of the virus in blood or other body fluids. PCR can provide a rapid and specific diagnosis of yellow fever in the early stages of the disease.

Another test is the virus isolation test. This involves culturing the virus from blood or other body fluids in a laboratory. Virus isolation can take several days to produce results, but it is the most specific and sensitive test for yellow fever.

Other laboratory studies may also be performed. These include:

<ul>
	<li>Complete blood count</li>
	<li>Liver function test</li>
	<li>Urinalysis</li>
	<li>Coagulation studies 
	&nbsp;</li>
</ul>

Chest X-rays may be used to evaluate patients for pulmonary edema. If the patient presents with an altered mental state, doctors may perform a CT scan.

It is important to note that laboratory confirmation of yellow fever is required for accurate diagnosis and to distinguish it from other viral hemorrhagic fevers. 
&nbsp;

Treatment

treatment. The goal of treatment is to relieve symptoms and prevent complications.

Supportive care may include: 
&nbsp;

<ol>
	<li>Rest And Hydration: Bed rest and plenty of fluids can help to relieve symptoms and prevent dehydration.</li>
	<li>Pain Relief: Painkillers such as acetaminophen can help to relieve fever and muscle pain.</li>
	<li>Treatment Of Complications: Severe cases of yellow fever may require hospitalization for treatment of complications such as liver failure, bleeding, and shock.</li>
</ol>

Prevention is the most effective way to control yellow fever. Vaccination is recommended for people living in or traveling to areas where yellow fever is endemic. The yellow fever vaccine is highly effective and provides long-lasting immunity. 
&nbsp;

Note: Aspirin and other NSAIDs (e.g., ibuprofen or naproxen) should be avoided as they can cause bleeding. Always contact a healthcare professional before taking any medications. 
&nbsp;

Yellow fever is a serious disease that can cause a range of complications. Some of the complications which are associated with yellow fever include: 
&nbsp;

<ol>
	<li>Liver Failure: Yellow fever can cause inflammation of the liver, which can lead to liver failure in severe cases. This can cause symptoms, such as abdominal pain, jaundice, and bleeding.</li>
</ol>

<ol start="2">
	<li>Bleeding Disorders: Yellow fever can cause bleeding disorders (e.g., DIC), including internal bleeding and bleeding from the nose, mouth, and eyes. This is a life-threatening complication.</li>
</ol>

<ol start="3">
	<li>Shock: In severe cases, yellow fever can cause shock, which is a life-threatening condition that occurs when the body is not getting enough blood flow. Symptoms of shock include rapid heartbeat, low blood pressure, and confusion.</li>
</ol>

<ol start="4">
	<li>Kidney Failure: Yellow fever can also cause damage to the kidneys, which can lead to kidney failure. This can cause symptoms such as swelling in the legs and feet, fatigue, and difficulty breathing.</li>
</ol>

<ol start="5">
	<li>Encephalitis: In rare cases, yellow fever can cause inflammation of the brain, a condition called encephalitis. This can cause symptoms such as fever, headache, confusion, and seizures.</li>
	<li>Secondary bacterial infections are also common in patients with yellow fever.</li>
	<li>Acute Respiratory Distress Syndrome (ARDS) can also develop in severe cases. 
	&nbsp;</li>
</ol>

Note: Overall, yellow fever can cause a range of complications, some of which can be life-threatening. It is important to take steps to prevent the disease, such as vaccination and mosquito control, and to seek prompt medical attention if you develop symptoms. 
&nbsp;

The risk factors for yellow fever include: 
&nbsp;

<ol>
	<li>Living In Or Traveling To Endemic Areas</li>
</ol>

Yellow fever is most commonly found in parts of Africa and South America, where the virus is transmitted by infected mosquitoes. 
&nbsp;

<ol start="2">
	<li>Lack Of Vaccination</li>
</ol>

People who have not been vaccinated against yellow fever are at higher risk of contracting the disease. 
&nbsp;

<ol start="3">
	<li>Age</li>
</ol>

Older adults are at higher risk of developing severe complications from yellow fever. 
&nbsp;

<ol start="4">
	<li>Weakened Immune System</li>
</ol>

People with weakened immune systems, such as those with <a href="https://merisehat.pk/disease/hiv-61">HIV</a>/<a href="https://merisehat.pk/disease/aids">AIDS </a>or undergoing chemotherapy, may be at higher risk of developing severe complications from yellow fever. 
&nbsp;

<ol start="5">
	<li>Mosquito Exposure</li>
</ol>

Mosquito bites increase the risk of contracting yellow fever, as the virus is transmitted by infected mosquitoes. 
&nbsp;

The most effective way to prevent yellow fever is through vaccination. The yellow fever vaccine is a live attenuated vaccine that provides long-term immunity against the virus. A live attenuated vaccine is a type of vaccine that is made from a weakened form of a disease-causing virus or bacterium. The virus or bacterium used in the vaccine is modified or &quot;attenuated&quot; so that it can no longer cause severe disease in healthy individuals, but can still stimulate an immune response that provides protection against the actual disease. The vaccine is recommended for people who are traveling to areas where yellow fever is endemic, such as sub-Saharan Africa and tropical South America. According to the World Health Organization (WHO), the yellow fever vaccine should be administered at least 10 days before travel to an endemic area to ensure adequate protection. The vaccine is highly effective, with a single dose providing lifelong protection in most cases.

The yellow fever vaccine is contraindicated in the following people: 
&nbsp;

<ul>
	<li>Immunocompromised individuals, such as those with HIV or cancers</li>
	<li>Pregnant or breastfeeding women (unless during an outbreak)</li>
	<li>People with severe allergies to egg protein</li>
	<li>Infants younger than 9 months of age 
	&nbsp;</li>
</ul>

In addition to vaccination, other measures can be taken to prevent yellow fever. These include<a href="#accordion">[3]</a>:

<ol>
	<li>Mosquito Control</li>
</ol>

Since yellow fever is spread by infected mosquitoes, it is important to take steps to prevent mosquito bites. This includes using insect repellent, wearing long-sleeved shirts and pants, and using mosquito nets.

<ol start="2">
	<li>Avoidance Of High-risk Areas</li>
</ol>

If possible, it is best to avoid areas where yellow fever is endemic. If travel to these areas is necessary, travelers should take extra precautions to prevent mosquito bites and should be vaccinated against the disease.

<ol start="3">
	<li>Awareness Of Symptoms</li>
</ol>

Knowing the symptoms of yellow fever can help individuals seek prompt medical attention if they become ill. Early diagnosis and treatment can help to prevent complications and improve outcomes.

Overall, prevention of yellow fever involves a combination of vaccination, mosquito control, and avoidance of high-risk areas. By taking these steps, individuals can protect themselves against this serious and potentially life-threatening disease. 
&nbsp;

Key Points

<ul>
	<li>Yellow fever is a viral disease caused by the yellow fever virus, which is transmitted to humans through the bite of infected mosquitoes.</li>
	<li>The initial symptoms of yellow fever are similar to those of other viral illnesses and can include fever, headache, muscle pain, and fatigue.</li>
	<li>Yellow fever is typically divided into three stages: the acute phase, the remission phase, and the toxic phase.</li>
	<li>Acute phase is the initial stage of the disease, which lasts for about 3-4 days.</li>
	<li>After the acute phase, most people recover and enter a remission phase, which lasts for about 24-48 hours.</li>
	<li>&nbsp;In some cases, the disease progresses to a more severe form, known as the toxic phase. It is characterized by jaundice, hepatitis, internal bleeding, vomiting blood, organ failure, and shock.</li>
	<li>Polymerase chain reaction (PCR) test detects the genetic material of the virus in blood or other body fluids and helps in confirming the diagnosis.</li>
	<li>A virus isolation test can take several days to produce results, but it is the most specific and sensitive test for yellow fever.</li>
	<li>There is no specific antiviral treatment for yellow fever, and supportive care is the mainstay of treatment. The goal of treatment is to relieve symptoms and prevent complications.</li>
	<li>Severe cases of yellow fever may require hospitalization for treatment of complications such as liver failure, bleeding, and shock.</li>
	<li>Yellow fever can cause inflammation of the liver, which can lead to liver failure in severe cases.</li>
	<li>In severe cases, yellow fever can cause shock, which is a life-threatening condition that occurs when the body is not getting enough blood flow.</li>
	<li>In rare cases, yellow fever can cause inflammation of the brain, a condition called encephalitis.</li>
	<li>People who have not been vaccinated against yellow fever are at higher risk of contracting the disease.</li>
	<li>Yellow fever can pose a significant risk to pregnant women, as it can cause severe illness and complications for both the mother and the developing fetus.</li>
	<li>The most effective way to prevent yellow fever is through vaccination. The yellow fever vaccine is a live attenuated vaccine that provides long-term immunity against the virus.</li>
	<li>According to the World Health Organization (WHO), the yellow fever vaccine should be administered at least 10 days before travel to an endemic area to ensure adequate protection.</li>
	<li>Since yellow fever is spread by infected mosquitoes, it is important to take steps to prevent mosquito bites. 
	&nbsp;</li>
</ul>