Yellow Fever

1. Yellow Fever Jamie Ye Honors Life Science Mrs. Schiller Period 1

2. Overview • The pathogen that causes yellow fever is the yellow fever virus, which has a spherical shape. • Yellow fever viruses have a diameter of 40-60 nanometers. • The yellow fever virus is an arbovirus of the flavivirus genus. • Arbovirus stands for arthropod-borne virus. • Arboviruses are spread through arthropods. • The arthropods are usually insects that suck blood, like mosquitoes.

3. Yellow Fever Virus These yellow fever viruses are at a magnification of 234,000.

4. History • Yellow fever is so named because it can cause jaundice, which makes a person’s skin and the whites of their eyes appear to be yellow. • Yellow fever most likely came from Africa, evolving from other similar viruses. • In the slave trade of the 1500s, it was spread to the New World.

5. Outbreaks in History • In the 1500s, Europeans living in the New World were devastated by the yellow fever. • During one expedition to capture Peru and Mexico in 1741, British forces were reduced by about 74% (27,000 soldiers to 7,000) because of yellow fever. • Throughout the seventeenth and eighteenth centuries, in the United States, towns on the coast and small villages were especially liable to have outbreaks of yellow fever.

6. Outbreaks Continued • There was an infamous outbreak of yellow fever in the United States in 1793. • It happened in Philadelphia, and killed about 4000-5000 people (no one is exactly sure how many people died). • In 1878, another epidemic occurred in over 100 United States towns, and killed over 20,000 people. • In the United States, the last yellow fever epidemic was in New Orleans during 1905.

7. Symptoms/Characteristics • The yellow fever virus usually incubates in the body for 3-6 days. • The infection can then have one or two phases. • The first phase can cause… • Fever • Muscle pain with noticeable backache • Headaches • Shivers • Loss of appetite • Vomit or nausea • After this first phase, most patients improve. • After 3-4 days, their symptoms disappear.

8. Symptoms/Characteristics Continued • 15% of yellow fever patients will go through a second, more harmful phase within a day of their short, first recovery. • This second phase can cause… • High fever • Jaundice • Abdominal pain with vomiting • Bleeding from the mouth, nose, eyes, or stomach • Blood in the vomit and feces after initial bleeding • Kidney and liver failure

9. Symptoms/Characteristics Continued • Within 10-14 days, half of the people who go through the second phase will die, while the rest recover. • The death rate of yellow fever can be from 15%-50%. • Yellow fever is not actually contagious, since contagious means that a disease/illness can be transmitted directly from one person to another. • The yellow fever virus is indirectly transmitted from person to person through mosquitoes.

10. Illnesses It Can Cause • Yellow fever can cause illnesses ranging from self-limited febrile illness to severe hepatitis and hemorrhagic fevers.

11. What It Does to Your Body • The yellow fever virus reproduces in the blood stream and in specific organs like the liver. • That leads to tissue damage. • A damaged liver causes many serious problems, like interference with blood-clotting mechanisms. • That causes the bleeding from the intestinal lining, gums, nose, etc. • Jaundice occurs when bilirubin, or yellow pigments, from a damaged liver colors the skin.

12. Populations at Risk • Yellow fever is endemic to 45 African and Latin American countries. • In total, that is a population of over 900 million people at risk. • In Africa, there are about 508 million people living in 32 countries that are at risk. • There are 13 countries in Latin America at risk. • Bolivia, Colombia, Ecuador, and Peru have the greatest risk.

13. Populations at Risk Continued • Every year, there are about 200,000 cases of yellow fever, with 30,000 deaths worldwide. • In countries where yellow fever is not native, there are a few number of cases where people “imported” the disease. • Asia is also at risk even though the disease has never been reported, since the region has everything needed for transmission.

14. Transmission • There are two types of yellow fever: jungle (sylvatic) yellow fever and urban yellow fever, both with a different cycle of infection. • A number of different species of the Aedes and Haemogogus mosquitoes can transmit yellow fever. • Walter Reed proved that yellow fever is transmitted to people through mosquitoes. • Domestic mosquitoes breed around houses. • Wild mosquitoes breed in the jungle. • Semi-domestic mosquitoes breed in both places.

15. Jungle Yellow Fever • The hosts of jungle yellow fever are usually monkeys (this is a monkey disease). • In tropical rain forests, infected wild mosquitoes spread it to monkeys. • The monkeys then infect any mosquito that bites them. • People can only contract it if a mosquito feeds on an infected monkey and then feeds on a person. • So, this is a rare disease, usually only occurring in people who work in the rain forest.

16. Urban Yellow Fever • Urban yellow fever is the disease that affects humans. • Aedes aegypti is the mosquito that usually transmits this disease from person to person. • For it to be spread to other people or introduced to an area, someone who was just infected by yellow fever has to live in or visit somewhere with the Aedes aegypti mosquito. • The mosquito then has to feed off that person and bite another one to infect the second person. • Large outbreaks occur in places with dense population and many non-immune people and Aedes mosquitoes.

17. A female Aedes aegypti mosquito while feeding

18. Prevention - Vaccination • The best way to prevent yellow fever is to get a vaccination. • The vaccine will give 95% of people who get vaccinated protection against yellow fever within one week. • One vaccination usually gives lifetime protection against the disease. • Sometimes travelers to and from specific places have to have a certificate of yellow fever vaccination. • Serious side effects caused by the yellow fever vaccine are very rare, and the vaccine is affordable as well.

19. Prevention – Mosquito Control • To help prevent yellow fever outbreaks, possible breeding places for mosquitoes should be destroyed. • Insecticides should be used in places where mosquitoes go through their early stages of growth, and on adult mosquitoes.

20. Prevention – Mosquito Bites • When you travel to a tropical area, watch out for mosquito bites. • Mosquitoes infected with yellow fever bite the most during the day, especially at dawn or dusk. • When outside: • Wear long-sleeved shirts and long pants • Treat clothing with insecticide • On any exposed skin, use insect repellent • When inside: • Try to stay in places with good screening • Use insecticide on living and sleeping areas

21. Treatment • Yellow fever cannot be treated, but rest, ibuprofen, naproxen, acetaminophen, or paracetamol could help treat the symptoms of fever and aching. • Also, yellow fever patients should be hospitalized so a doctor can treat the complications (liver failure, etc.) • Antibiotics can be used for bacterial infections affiliated with yellow fever. • Yellow fever patients should avoid exposure to mosquitoes so they don’t help the transmission cycle.

22. Works Cited • 8239. 1980. Photograph. Public Health Image Library. Web. 8 May 2010. <http://phil.cdc.gov/phil/home.asp>. • “Arbovirus Facts." Directors of Health Promotion and Education. Web. 08 May 2010. <http://www.dhpe.org/infect/Arbovirus.html>. • Gathany, James. 8932. 2006. Photograph. Public Health Image Library. Web. 8 May 2010. <http://phil.cdc.gov/phil/home.asp>. • Murphy, Jim. An American Plague: the True and Terrifying Story of the Yellow Fever Epidemic of 1793. New York: Clarion, 2003. Print. • "Yellow Fever Fact Sheet." Centers for Disease Control and Prevention. 11 June 2007. Web. 08 May 2010. <http://www.cdc.gov/ncidod/dvbid/yellowfever/YF_FactSheet.html>.

23. Works Cited Continued • "Yellow Fever Frequently Asked Questions." Centers for Disease Control and Prevention. 16 Aug. 2007. Web. 08 May 2010. <http://www.cdc.gov/ncidod/dvbid/yellowfever/yf_faq.html>. • "Yellow Fever." MSU Entomology Group. Web. 08 May 2010. <http://entomology.montana.edu/historybug/yellow_fever.htm>. • "Yellow Fever Virus Picture." Hardin MD. University of Iowa. Web. 9 May 2010. <http://www.lib.uiowa.edu/hardin/md/cdc/2176.html>. • "Yellow Fever." World Health Organization. Dec. 2009. Web. 08 May 2010. <http://www.who.int/mediacentre/factsheets/fs100/en/>.

24. *Note about image link in words cited • The images cited in the works cited section are from a database that doesn’t store your search results. • So, to find the images, search “yellow fever virus.”