Plate 84

Viral Diseases of the Digestive and Lymphoid Organs

Viral Gastroenteritis

• Viral gastroenteritis: inflammation of stomach and intestines

• Often called “stomach flu”, although it is not caused by the influenza virus

• Symptoms: primarily diarrhea and vomiting, but also headaches, fever, and stomach-ache

Yellow fever

• Sometimes known as “yellow jack” or “black vomit”

• Called “yellow fever” because of the jaundice that it causes

• RNA icosahedral (Flaviviridae family) virus

Symptoms• 3-6 days of incubation, then

3-4 days of fever and muscle pain

• Most patients improve and symptoms disappear

• 15% of patients enter a 2nd toxic phase:– Bleeding from mouth, nose,

eyes, and/or stomach– Kidney failure– Jaundice– 50% mortality in 14 days

• No cure, just treatment for symptoms

Symptoms

• Jaundice – “yellowing” of skin and eyes

• Bile passes from the gallbladder and/or liver into the bloodstream

Transmission

• The virus is transmitted via mosquito bites

• Virus passes from the mosquito’s saliva to the human bloodstream

• Can also pass from monkeys to mosquitoes to humans

Aedes aegypti mosquito

Transmission• Estimated 200,000

cases and 30,000 deaths per year worldwide

• Vaccine is very effective

• Cases have increased over the past 20 years due to urbanization, deforestation, and climate change

Philadelphia• Summer 1793, French refugees (some who had

Yellow Fever) fled the Haitian Revolution and came to Philadelphia

• By November 1793, about 5,000 Philadelphians had died (more than 10% of population)

• Summer 1794, Yellow Fever returned, but not as severely, and also in 1796 and 1797

• Another severe epidemic came in 1798, killing 1,292 Philadelphians

• At the peak of the 1798 epidemic, all but 7,000 residents had left the city

Dengue Fever

• Also known as “break-bone” fever

• RNA icosahedral (Flaviviridae family) virus

DF - Symptoms• Dengue fever has symptoms

which can be very similar initially to flu

• Most people suffer from headaches and fever, some get muscle and bone pains

• An infected person can feel tired for up to three months, but will not usually need treatment

• May lead to Dengue Hemorrhagic Fever (DHF), which is potentially lethal

DF - Symptoms (continued)

Itchy rash. Everywhere I had ever been injured hurt again. Achy like the flu but worse. Exhausted. Literally took months to regain full energy and stamina.

DF - History

• Dengue fever originated in primates and “jumped” to humans 100-800 years ago

• Because of disruption from WWII and international trading of cargo, the Aedes mosquito has spread to tropical regions around the world

• Not until 1981 that the disease became problematic in Latin America and the Caribbean

DF - Location

• 40% of the world’s population live in areas where they are at risk for dengue transmission

• WHO estimates that there are 50-100 million infections a year and 22,000 deaths

• http://www.healthmap.org/dengue/index.php

DF - Treatment

• There is no cure for dengue fever nor is there specific medication for it

• Patients should rest, take pain-relievers, and drink plenty of fluids

DF - Transmission

• Dengue viruses are mainly transmitted by the bite of infected Aedes aegypti mosquitoes

Mononucleosis

• The “kissing disease”• Epstein-Barr virus

(human herpesvirus 4)

Mono - Symptoms

Mono - Symptoms

Mono Symptoms - Swollen Tonsils

Mono - Transmission

• Virus spread through salivary drops

Hepatitis A

• RNA enterovirus (hepatitis A virus – HAV)

HAV - Symptoms

• Can cause:– Swelling of the liver– Jaundice– Fatigue– Loss of appetite– Diarrhea

HAV - Transmission

• Spread primarily by food or water contaminated by stool from an infected person

• Eating food prepared by someone with HAV who did not wash their hands after using the bathroom

Hepatitis B

• Hepadnavirus (hepatitis B virus – HBV)

HBV - Symptoms

• Short-term HBV resembles symptoms of the flu

• Possible symptoms include fever, dark urine, vomiting, and jaundice

• Long-term HBV (chronic HBV) lasts a lifetime and can lead to scarring of the liver, liver failure, and liver cancer

• Interferon can be used to slow the virus from damaging the liver

HBV - Transmission

• HBV is spread through contact with blood, semen, or other body fluids of an infected person

Hepatitis C

Symptomsjaundice, fatigue, dark urine, nausea

Long terminfections (55-85%), leading indication for transplant,

Info.No vaccine, interferon, do not share personal items, rarely STD

Hepatitis D

Symptomsjaundice, fatigue, tea-colored urine joint pain

Long Termmore sever acute disease & risk of failure

Info.acquires along with HBV

Hepatitis E

SymptomsJaundice, dark urine, loss appetite, fatigue

Long Termno long term often seen in pregnancy

Info.highest among 15-40 yo, contaminated water