Yellow Fever

YELLOW FEVER ERADICATION

Campaigns to eradicate A. aegypti, the so-called yellow fever mosquito, from Cuba and Panama were highly successful in eliminating urban YF cases. •Unfortunately, the goal of YF eradication was thwarted by YF being a zoonotic disease, maintained by sylvatic mosquito species and nonhuman primates in the Amazon jungle.

Apoptotic masses known as

Councilman bodies (also known as Apoptotic body) appear in the cytoplasm of hepatocytes.

How is yellow fever spread?

Spread through mosquito bites •It cannotbe spread person to person by direct contact.

what is *flavus known for?

is Latin for "yellow", and yellow fever in turn was named because of its propensity to cause jaundice in victims.

Who determined that the yellow fever was transmitted by mosquitoes?

late 1800's Carlos Finlay, a cuban scientist

a single dose of vaccine for yellow fever provides?

life-long protection against yellow fever disease

Early on it was realized yellow fever was not contagious but the source was attributed to?

miasmas

Initial symptoms of yellow fever?

most common are fever, muscle pain with prominent backache, headache, loss of appetite, and nausea or vomiting. •Many people do not experience symptoms •In most cases, symptoms disappear after 3 to 4 days.

small percentage of patients with yellow fever enter a ?

second, more toxic phase within 24 hours of recovering from initial symptoms. •High fever returns •Several body systems are affected, usually the liver and the kidneys. •In this phase people are likely to develop jaundice (yellowing of the skin and eyes, hence the name 'yellow fever'), •Dark urine •Abdominal pain with vomiting •Bleeding can occur from the mouth, nose, eyes or stomach.

Yellow fever can be confused with?

severe malaria, leptospirosis, viral hepatitis, other hemorrhagic fevers, infection with other flaviviruses (such as dengue hemorrhagic fever), and poisoning

when are People infected with yellow fever virus are infectious to mosquitoes?

shortly before the onset of fever and up to 5 days after onset.

VIRAL HEMORRHAGIC FEVERS (VHFS)

The viruses that cause hemorrhagic fever are mainly RNA and have envelop. Severe multisystem syndrome (multiple organ are affected). Often accompanied by hemorrhage (bleeding) vascular system is damaged Body's ability to regulate itself is impaired.

What does the word "yellow" refer to in the yellow fever?

to the jaundice that affects some patients.

3rd yellow fever: urban: transmission cycle involves?

transmission of the virus between humans and urban mosquitoes

1st yellow fever: Jungle (sylvatic) transmission cycle involves?

transmission of the virus between non-human primates (e.g., monkeys) and mosquito species found in the forest canopy

2nd yellow fever: Intermediate (savannah): transmission cycle involves?

transmission of virus from mosquitoes to humans living or working in jungle border areas.

How may fatality occur from yellow fever?

when cytokine storm, shock, and multiple organ failure follow.

virus caused by yellow fever

•Family: Flaviviridae* •Genus:Flavivirus •Species:Yellow fever virus

YELLOW FEVER VIRUS; REPLICATION

•The viruses infect, monocytes, macrophages, Schwann cells, and dendritic cells. •They attach to the cell surfaces via specific receptors and are taken up by receptor-mediated endocytosis. •After entering the host cell, the viral genome is replicated in cytoplasm (the rough endoplasmic reticulum (ER)) •Virions are released through the cell membrane.

Where is yellow fever found?

certain parts of Africa and South America. •200,000 cases of disease and 30,000 deaths each year, with 90% occurring in Africa.

About what average of infected people with yellow fever develop serious illness?

20-50% can lead to bleeding, shock, organ failure, and sometimes death.

Epidemiology: how many cases and deaths occur each year?

200,000 cases of disease and 30K deaths with 90% occurring in Africa.

YELLOW FEVER VACCINE

A safe and effective yellow fever vaccine has been available for more than 80 years. •The vaccine is a live, weakened form of the virus given as a single shot.

What is yellow fever?

Acute viral hemorrhagic disease spread by mosquitos

where did yellow fever originate

Africa and was introduced into Europe and the Americas as a result of the slave trade between these two continents.

Which mosquitos transmit the virus from person to person?

Infected mosquitoes of the Aedes aegypti specie A mosquito-borne disease

Incubation time for yellow fever?

3 to 6 days. •Symptoms take 3-6 days to develop

half of the patients who enter the toxin phase die within?

7 -10 days.

First recorded epidemic of yellow fever

In 1648, the Yucatan, The indigenous Mayan people called the illness xekik("blood vomit").

what can verify To confirm the cause of death for yellow fever?

Liver biopsy can verify inflammation and necrosis of hepatocytes and detect viral antigens. •Because of the bleeding tendency of yellow fever patients, a biopsy is only advisable post mortem to confirm the cause of death.

What can detect yellow fever in the early stages?

Polymerase chain reaction (PCR) testing in blood and urine

What does the activation of macrophages serve as?

a more direct attack on the virus by prompting the detection and engulfing of the pathogen before it spreads. The response, however, results in the overproduction of cytokines which encourages vascular leakage and low blood pressure, giving the class its hemorrhagic characteristics

Excessive cytokine production results in

apoptosis of lymphocytes

Eliminate Yellow fever Epidemics (EYE) Strategy has launched in 2017 to protect

at-risk populations, preventing international spread, and containing outbreaks rapidly. •By 2026, it is expected that more than 1 billion people will be protected against the disease.

How is yellow fever prevented?

by an extremely effective vaccines (safe and affordable).

Treatment for Yellow fever?

no specific anti-viral but specific care to treat dehydration, liver and kidney failure, and fever Rehydration and pain relief and antibiotics for some associated bacterial infections

What gender of mosquito transmit yellow fever?

only the female mosquito bites humans

In later stages, how is yellow fever detected?

testing to identify antibodies is needed.

From lymph nodes, the yellow fever virus goes to?

the blood (viremia) and reach the liver and infect hepatocytes which leads to the release of cytokines and release of enzymes, that ultimately reduces the organ's production of clotting factors.

What effect does yellow fever have on dendritic cells?

the innate response of cytokine production takes place in hopes of activating macrophages.

What happens after transmission of yellow fever from a mosquito?

the viruses infect dendritic cells and the lymph nodes.