How Does Yellow Fever Spread and How Can You Stay Protected?
Yellow fever is a deadly flu - disease. This is one of the great epidemic diseases of the world. Mosquitoes called Aedes aegypti act as a carrier for spreading yellow fever, they also transmit other diseases like dengue and Zika viruses. Aedes aegypti mosquitoes spread flavivirus, which infects human beings, all species of monkeys, and other small mammals.
Yellow fever disease causes the same problem as high fever and jaundice. Jaundice usually is yellowing the skin and eyes. That’s why this disease is termed yellow fever. Still, the people from Africa and South America suffer a lot due to Yellow fever. It still remains, as the forest monkeys act as a reservoir of Yellow fever.
Origin of Yellow Fever
In the 16th century, the Spanish conquered South America. The first outbreak of yellow fever disease was found in South Africa. Later, Western Africa emerged as the home of yellow fever. It remains untreated for the next 300 years and it remains one of the great plagues for the entire world. Also, the yellow fevers are names Yellow Jack and ‘the saffron scourge’. Later the outbreaks spread through various parts of tropical and subtropical regions includes, including New York, Spain, France, England Italy, etc.
In the late 19th century, many people came up with several research theories about the cause and transmission of yellow fever. But the Scottish medical historian Charles Creighton found that yellow fever disease is initially originated from African slaves. He summarized yellow fever as ‘a virulent filth disease. Ancient people treated this infection with ipecacuanha to induce vomiting, castor oil to loosen the motion, and enemas of cold water with turpentine to release gas.
In 1881 Cuban epidemiologist Carlos Juan Finlay found that the Aedes aegypti acts as the medium to transmit the disease. Later, the US Army bacteriologist and pathologist, Major Walter Reed demonstrated the transmission of yellow fever from one human to another through the Aedes mosquito bites. Reed further found that the mosquitoes were the only vector of the disease. American surgeon William Crawford Gorgas was immediately taken measures to control Aedes Mosquitos to avoid spreading. Using this method, he eradicated yellow fever from Rio de Janeiro, Brazil, Panama, and all other places. In 1927 researchers from Rockefeller Institute for Medical Research started working on vaccines using the strains of the virus. In 1933, researchers found large transmissions are involving in the transmission of the virus from animal to animal, animal to human..etc. Majority of the people affected by yellow fever during World War II. Many immunization programs with fever injection provided by various institutions saved many lives. Even though the monkey population is high in tropical Asia if it enters tropical Asia, it may put many lives at risk. But It does not touch Asia, as the ecological condition does not support the transmissions of yellow fever. According to the report of the World Health Organization, yearly about 30,000 people lose their lives due to yellow fever.
Causes of Yellow Fever
The infected Aedes aegypti mosquitoes spread yellow fever. Based on the cause they are classified as
.Urban Yellow Fever, which transmits from one person to another person through domestic mosquitoes. Aedes aegypti mosquito
Jungle yellow fever, which transmits from mammalian host to human via forest mosquitoes (e.g., Haemagogus in South America, A. analyzepatient’santibodytreatmentGood in Africa)
Savannah yellow fever, which transmits from animal to person or person to person through semi-domestic mosquitoes, (e.g., A. furcifer, A. taylori).
Symptoms of Yellow Fever
The symptoms of yellow fever disease are similar to jaundice, malaria, dengue, or leptospirosis. Once the infected mosquito bit the individual, the virus enters the body and takes some time to develop inside the body.
The Symptoms like:
Fever
Headache
Vomiting
Nausea
Eyes and skin turns yellow
Chills
Fatigue
Loss of appetite
The severe case may cause the failure of heart, liver, and kidney functions. It is possible to face death if it remains untreated for long days.
[Image will be Uploaded Soon]
This image shows the clear symptoms of yellow fever, which shows in various parts of the body.
Diagnostic Method for Yellow Fever
Doctors analyze the patient’s travel history. And interlink with the symptoms of the patients. Later, the doctors collect the blood sample to analyze the antibody generated in the patients’ body to fight against the disease.
Yellow Fever Treatment
There is no specific yellow fever treatment. Good nursing and supportive care help to overcome the infection soon. Controlling the mosquito population and eliminating it may eradicate the disease. People are using fever injection to improve their immune systems. Providing enough fluids, oxygen, and maintaining regular blood pressure helps the infected person to come out of it soon.
Prevention Methods for Yellow Fever
The vaccination is the only method for completely preventing the risk of yellow fever. The fever injection with virus strain of vaccine protects from causes of yellow fever.
FAQs on Yellow Fever: Causes, Symptoms, and Prevention
1. What is the main cause of yellow fever?
The main cause of yellow fever is a virus from the Flavivirus genus. It is an RNA virus transmitted to humans primarily through the bite of infected mosquitoes, most commonly the Aedes aegypti and Haemagogus species. These mosquitoes act as vectors, carrying the virus from infected primates (monkeys) or humans to healthy individuals.
2. What are the typical symptoms of a yellow fever infection?
Symptoms of yellow fever typically appear 3 to 6 days after being infected. The illness often occurs in two phases. The initial acute phase includes:
- Fever and chills
- Severe headache and back pain
- General body aches
- Nausea and vomiting
- Fatigue and weakness
While most patients recover after this phase, about 15% enter a more severe, toxic phase, which includes symptoms like high fever, jaundice, bleeding, and eventually shock and multi-organ failure.
3. Why is the disease called 'yellow fever'?
The disease gets its name from one of its most prominent and severe signs: jaundice. In the toxic phase of the illness, the virus can cause severe liver damage. This impairs the liver's ability to process bilirubin, a yellow pigment, which then builds up in the bloodstream, causing the skin and the whites of the eyes to turn yellow. This yellowing (jaundice) combined with a high fever gives the disease its name.
4. How is yellow fever diagnosed and treated?
Yellow fever is diagnosed through a blood test that can detect the virus itself (using PCR) or the antibodies the body produces to fight it (using ELISA). There is no specific antiviral medication to cure yellow fever. Treatment is supportive and focuses on managing symptoms, which includes getting plenty of rest, staying hydrated with fluids, and using pain relievers and fever reducers. Severe cases require hospitalisation for intensive care to manage complications like organ failure and bleeding.
5. What is the role of mosquitoes in the yellow fever transmission cycle?
Mosquitoes are the biological vectors of the yellow fever virus. The transmission cycle works as follows:
- A female mosquito (like Aedes aegypti) bites an infected primate or human, ingesting the virus with the blood.
- The virus incubates and replicates within the mosquito.
- The now-infective mosquito bites a healthy human, injecting the virus into their bloodstream.
This cycle allows the disease to spread rapidly in areas where both the virus and the mosquito vector are present.
6. How does yellow fever differ from other mosquito-borne diseases like Dengue and Malaria?
While all are spread by mosquitoes, they differ significantly:
- Causative Agent: Yellow fever and Dengue are caused by viruses (Flaviviruses), whereas Malaria is caused by a protozoan parasite (Plasmodium).
- Key Symptoms: Yellow fever is uniquely characterised by severe jaundice and haemorrhagic fever in its toxic phase. Dengue is known as "breakbone fever" for the severe joint and muscle pain it causes. Malaria is typified by recurring cycles of high fever, chills, and sweating.
- Prevention: A highly effective and long-lasting vaccine is available for yellow fever, which is not the case for Malaria or Dengue, where prevention focuses more on avoiding mosquito bites and prophylactic drugs (for Malaria).
7. What happens in the toxic phase of yellow fever and why is it so dangerous?
The toxic phase occurs in about 15% of patients after a brief remission from initial symptoms. It is extremely dangerous because it involves systemic organ failure. Key developments include:
- Liver Failure: Leads to severe jaundice and a failure to produce clotting factors, causing bleeding.
- Kidney Failure: The kidneys stop filtering waste from the blood.
- Haemorrhagic Fever: The patient experiences bleeding from the mouth, nose, eyes, and stomach, leading to blood in vomit (black vomit) and stool.
This rapid deterioration and multi-organ failure are why the mortality rate for patients entering the toxic phase can be as high as 50%.
8. What is the status of yellow fever in India?
India is not an endemic country for yellow fever, meaning the virus does not naturally circulate here. However, the mosquito vector, Aedes aegypti, is widespread across the country. To prevent the introduction and spread of the virus, the Indian government has strict regulations. Travellers arriving from countries where yellow fever is endemic are required to present proof of yellow fever vaccination to gain entry.
9. Can a person who recovers from yellow fever get infected again?
No, a person who recovers from a yellow fever infection develops lifelong immunity. The body's immune system produces specific antibodies against the virus during the infection. These antibodies remain in the body and provide robust, long-term protection against any future encounters with the yellow fever virus.
