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Hepatitis Viruses

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الكلية كلية الصيدلة     القسم  فرع البايولوجي     المرحلة 2
أستاذ المادة امل طالب عطية نعمة السعدي       11/03/2018 19:33:33


1. Introduction

The genus Hepatovirus (formerly named Hepatitis virus) is a genus of family Picornaviridae causing infectious Hepatitis (The plural is hepatitides) naturally in humans and experimentally in other primates.
The word "Hepatitis" is derived from the Greek "hêpar" meaning “liver”, and the suffix "it is", meaning “inflammation”.
Hepatitis is a disease of the liver characterized by the presence of inflammatory cells in the tissue of the liver. Hepatitis may occur without symptoms, but can lead to jaundice , poor appetite, and fatigue.
Hepatitis can manifest either as an acute or as a chronic disease. Acute hepatitis can be self-limiting (resolving on it s own), can progress to chronic hepatitis, or can cause acute liver failure in rare instances. Chronic hepatitis may have no symptoms, or may progress over time to fibrosis (scarring of the liver) and cirrhosis (chronic liver failure). Cirrhosis of the liver increases the risk of developing Hepatocellular Carcinoma (a form of liver cancer).
Viral hepatitis has emerged as a major public health problem throughout the world affecting several hundreds of millions of people. Viral hepatitis is a cause of considerable Morbidity and Mortality in the human population, both from acute and chronic infection.

2. Signs and Symptoms of Hepatitis
Hepatitis has a broad spectrum of presentations that range from a complete lack of symptoms to severe liver failure. The acute form of hepatitis, generally caused by viral infection, is characterized by constitutional symptoms that are typically self-limiting. Chronic hepatitis presents similarly, but can manifest signs and symptoms specific to liver dysfunction with long-standing inflammation and damage to the organ.

2.1 Acute Hepatitis
Acute viral hepatitis follows a pattern of infection that involves three distinct phases:
The First:
The initial prodromal phase relating to early symptoms that may mark the onset of a disease. involves non-specific and flu-like symptoms common to many acute viral infections. This includes fatigue(overall feeling of tiredness or lack of energy), nausea, vomiting, poor appetite, joint pain, and headaches and fever. Late in this phase, people can experience liver-specific symptoms, including choluria /(k?-lur ?-?)/ (Bile in the urine) and claycolored stools.
The Second:
Clinical jaundice (yellowing of the skin) and icterus /?ikt?r?s/ (yellowing of the eyes) follow the prodrome after about 1–2 weeks and can last for up to 4 weeks. The non-specific symptoms seen in the prodromal typically resolve by this time, but people will develop an enlarged liver and right upper abdominal pain or discomfort /dis?k?mf?rt/.
10–20% of people will also experience an enlarged spleen, while some people will also experience a mild unintentional weight loss.
The Third:
The recovery phase is characterized by resolution of the clinical symptoms of hepatitis with persistent elevations in liver lab values and potentially a persistently enlarged liver. All cases of hepatitis A and E are expected to fully resolve after 1–2 months.
A majority of hepatitis B cases are also self-limited and will resolve in 3–4 months. Few cases of hepatitis C will resolve completely.

2-2. Chronic Hepatitis
Chronic hepatitis is often asymptomatic early on in it s course and is detected only by liver laboratory studies for screening purposes or to evaluate non-specific symptoms. As the inflammation progresses, patients can develop constitutional symptoms similar to acute hepatitis including fatigue, nausea, vomiting, poor appetite, and joint pain. Jaundice and icterus can occur as well, but occur much later in the disease process and are typically a sign of advanced disease.

Chronic hepatitis interferes with hormonal functions of the liver which can result in acne/ ?akn?/( the occurrence of inflamed or infected sebaceous glands in the skin; in particular, a condition characterized by red pimples on the face, prevalent chiefly among teenagers), hirsutism/ ?h?rso?o?tiz?m,/ (abnormal hair growth), and amenorrhea (lack of menstrual period /menstr(o?o)?l/ in women. Extensive damage and scarring of the liver over time defines cirrhosis/s??r?s?s/, a condition in which the liver’s ability to function is permanently impeded. This results in jaundice, weight loss, coagulopathy( a bleeding disorder), ascites
\?-?s?-t?z\ (abdominal fluid collection), and peripheral edema (leg swelling).
Cirrhosis can lead to other life-threatening complications such as hepatic encephalopathy( It is caused by accumulation in the bloodstream of toxic substances that are normally removed by the liver), Esophageal Varices (Esophageal varices are abnormal, enlarged veins in the esophagus, it develop when normal blood flow to the liver is blocked by a clot or scar tissue in the liver), hepatorenal syndrome, and liver cancer.
3. Causes of Hepatitis
Hepatitis is inflammation of the liver. It can be caused by viruses, alcohol or substance use, exposure to toxins, and certain diseases. Viral hepatitis refers to liver inflammation caused by one of several types of viruses that attack the liver. Causes of hepatitis can be divided into the following major categories:
• Infectious Hepatitis caused by viruses or bacteria or parasites.
• Metabolic Hepatitis includes Toxins, drugs, alcohol, and lipids are metabolic causes of liver injury and inflammation.
• Ischemic Hepatitis /ih-skee-mik/ (Ischemia is a local deficiency in blood supply to liver as in shock, heart failure, or vascular insufficiency, causing a shortage of oxygen and glucose needed for cellular metabolism (to keep tissue alive). to the liver

• Autoimmune Hepatitis.
• Genetic Hepatitis, and others.

3-1. Autoimmune Hepatitis
Autoimmune hepatitis is a chronic disease caused by an
abnormal immune response against liver cells. The disease
is thought to have a genetic predisposition (an inherited genetic pattern that makes one susceptible to a certain disease) as it is associated with certain human leukocyte antigens involved in the immune response. As in other autoimmune diseases, circulating Auto-Antibodies may be present and are helpful in diagnosis. For example of Auto-antibodies found in patients with autoimmune hepatitis is the sensitive but less specific anti-nuclear antibody (ANA).
Autoimmune hepatitis can present anywhere within the
spectrum from asymptomatic to acute or chronic hepatitis
to fulminant liver failure. The diagnosis is suspected on the basis of abnormal liver function tests. Autoimmune hepatitis increases the risk for cirrhosis, and the risk for liver cancer is increased by about 1% for each year of the disease.

3-2. Infectious Hepatitis
3.2.1. Viral hepatitis
Viral hepatitis is the most common type of hepatitis worldwide. Viral hepatitis is caused by five different viruses (hepatitis A, B, C, D, and E).
Hepatitis A and hepatitis E behave similarly: they are both transmitted by the fecal-oral route, are more common in developing countries, and are self-limiting illnesses that do not lead to chronic hepatitis.
Hepatitis B, hepatitis C, and hepatitis D are transmitted when blood or mucus membranes are exposed to infected blood and body fluids, such as semen and vaginal secretions. Viral particles have also been found in saliva and breastmilk.
Hepatitis B and C can present either acutely or chronically. Hepatitis D is a defective virus that requires hepatitis B to replicate and is only found with hepatitis B co-infection.

4. The Mechanism
The specific mechanism varies and depends on the underlying cause of the hepatitis. Generally, there is an initial insult that causes liver injury and activation of an inflammatory response, which can become chronic, leading to progressive fibrosis and cirrhosis.

4-1. Viral Hepatitis
The pathway by which hepatic viruses cause viral hepatitis is best understood in the case of hepatitis B and C.
The viruses do not directly cause apoptosis (cell death). Rather, infection of liver cells activates the innate and adaptive arms of the immune system leading to an inflammatory response which causes cellular damage and death. Depending on the strength (strong )of the immune response, the types of immune cells involved and the ability of the virus to evade the body’s defense, infection can either lead to clearance (acute disease) or persistence (chronic disease) of the virus.
The chronic presence of the virus within liver cells results in multiple waves of inflammation, injury and wound healing that overtime lead to scarring or fibrosis and culminate in hepatocellular carcinoma. Individuals with an impaired immune response are at greater risk of developing chronic infection.

5. Diagnosis
Diagnosis of hepatitis is made on the basis of some or all of the following:
• a patient’s signs and symptoms.
• medical history.
• blood tests.
• liver biopsy.
In general, for viral hepatitis and other acute causes of hepatitis, the patient’s blood tests and clinical picture are sufficient for diagnosis.

5-1. Screening of Viral hepatitis
The purpose of viral screening for viral hepatitis is to identify people infected with the disease as early as possible. This allows for early treatment, which can prevent disease progression, and decreases transmission to others.
Glossary
jaundice
/jônd?s/ a yellow discoloration of the skin, mucous membranes, and conjunctiva of the eyes, arising from excess of the pigment bilirubin and typically caused by liver disease,
fatigue overall feeling of tiredness or lack of energy
self-limiting (resolving on it s own),
fibrosis scarring of the liver: scar tissue replaces normal, healthy tissue in your liver. It happens after the healthy cells are damaged over a long period of time, usually many years. The scar tissue makes the liver lumpy and hard, and after a while, the organ will start to fail
cirrhosis
/ s??r?s?s/
chronic liver failure, Cirrhosis is a complication of liver disease which develops when scar tissue replaces normal, healthy tissue in your liver. It happens after the healthy cells are damaged over a long period of time, usually many years. The scar tissue makes the liver lumpy and hard, and after a while, the organ will start to fail.
Ischemia Ischemia is a local deficiency in blood supply to tissues, causing a shortage of oxygen and glucose needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue.

Coagulopathy (also called a bleeding disorder) is a condition in which the blood s ability to coagulate (form clots) is impaired. This condition can cause a tendency toward prolonged or excessive bleeding (bleeding diathesis), which may occur spontaneously or following an injury or medical and dental procedures.


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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