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Viral structure and functions
Hepatitis B and Hepatitis D virus
Epstein-Barr virus (Infectious mononucleosis)
Herpes simplex virus
Human herpesvirus 6 (Roseola)
Human herpesvirus 8 (Kaposi sarcoma)
Varicella zoster virus
BK virus (Hemorrhagic cystitis)
JC virus (Progressive multifocal leukoencephalopathy)
Poxvirus (Smallpox and Molluscum contagiosum)
Lymphocytic choriomeningitis virus
Hepatitis C virus
West Nile virus
Yellow fever virus
Human parainfluenza viruses
Respiratory syncytial virus
Hepatitis A and Hepatitis E virus
Human T-lymphotropic virus
Eastern and Western equine encephalitis virus
Prions (Spongiform encephalopathy)
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Hepatitis A and E are two viruses that cause acute hepatitis.The name comes from the word hepat - meaning liver, and suffix -itis to label inflammatory disease, meaning that hepatitis is an inflammation of the liver. They tend to cause hepatitis epidemics, especially in children and young adults.
Now, even though they cause the same disease, Hepatitis A and E viruses come from different families. Hepatitis A is a picornavirus, while hepatitis E is a hepevirus. They are naked viruses, made of a single strand RNA surrounded by a capsid, which is a spherical protein shell. And they’re “naked” because the capsid isn’t covered by a lipid membrane.
These viruses are transmitted by the fecal-oral route, in other words, you catch it by ingesting stool particles of someone who is sick - yuck! This usually happens if infected stool ends up in the food, water and shellfish, or on surfaces. So usually, outbreaks can often be traced to the same source of food or water, and they also tend to be common in day-care centers.
Ok, now, when you eat, food travels through your pharynx, esophagus, stomach, duodenum and intestines. In the intestines all of the nutrients are absorbed and go through hepatic portal venous system, which is a system of veins that carry blood from the spleen, pancreas and intestines to the liver. And just like nutrients, the hepatitis A or E reach the liver through the hepatic portal venous system.
Now, the liver is made of functional units called hepatic lobules. The main cells are called hepatocytes, and their main job is to use a huuuge array of enzymes to detoxify harmful substances from our blood - like drugs or alcohol; synthesize a variety of important proteins, like coagulation factors; and convert cholesterol into bile salts which along with water and bilirubin make up the bile. Bile flows into the bile ducts and eventually reaches the gallbladder, which is a small pear-shaped hollow organ located beneath the liver. This is where bile is stored and becomes more concentrated. Another type of liver cells are the Kupffer cells, which are modified macrophages scattered through the lobules, that destroy old red and white blood cells, bacteria, and other foreign substances.
Hepatitis viruses A and E are RNA viruses that can cause acute hepatitis, and they are both RNA viruses transmitted via the feco-oral route. However, hepatitis E is not as common as hepatitis A, and usually affects developing countries. Symptoms of both types of hepatitis include fever, nausea, vomiting, diarrhea, and abdominal pain.
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