1 Assignment1401(infectious__ disease)

InfluenzaInfluenza or the flu is a common, infectious respiratory disease caused by a RNA virus –influenza virus. It is highly contagious and spreads rapidly from person to person by droplet. Influenza typically starts with a headache, chills and cough, followed rapidly by fever, loss of appetite, muscle aches and fatigue, running nose, sneezing, watery eyes and throat irritation. Nausea, vomiting and diarrhea may also occur, especially in children. Most people will recover from influenza within a week or ten days, but some - including those over 65 and adults and children with chronic conditions, such as diabetes and cancer - are at greater risk of more severe complications, such as pneumonia. People with the flu are advised to get plenty of rest, drink plenty of liquids, avoid using alcohol and tobacco and, if necessary, take medications such as acetaminophen to relieve the fever and muscle aches associated with the flu. Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin during an influenza infection (especially influenza type B), because doing so can lead to Reye's syndrome, a rare but potentially fatal disease of the liver. Since influenza is caused by a virus, antibiotics have no effect on the infection; unless prescribed for secondary infections such as bacterial pneumonia. Antiviral medication can be effective, but some strains of influenza can show resistance to the standard antiviral drugs.Dengue feverDengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen glands (lymphadenopathy), and rash. Because it is caused by one of four serotypes of virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular serotype to which the patient was exposed. After being bitten by a mosquito carrying the virus, the incubation period ranges from three to 15 (usually five to eight) days before the signs and symptoms of dengue appear. Dengue starts with chills, headache, pain upon moving the eyes, and low backache. Painful aching in the legs and joints occurs during the first hours of illness. The temperature rises quickly as high as 40 C, with relative low heart rate (bradycardia) and low blood pressure (hypotension). The eyes become reddened. A flushing or pale pink rash comes over the face and then disappears. The glands (lymph nodes) in the neck and groin are often swollen.The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can inflict the disease. The virus is not contagious and cannot be spread directly from person to person. There must be a person-to-mosquito-to-another-person pathway. Most people recover from dengue fever after a few days and its fatality rate is 3/10000 which most happed in the severe patient because of central respiration failure. There is no specific treatment for dengue fever but medical care can improve patient outcomes.Hepatitis BHepatitis B is an infectious hepatitis caused by the hepatitis B virus (HBV). This infection has two possible phases; 1) acute and 2)chronic. Acute hepatitis B refers to newly acquired infections. Affected individuals notice symptoms approximately 1 to 4 months after exposure to the virus. In most people with acute hepatitis, symptoms resolve over weeks to months and they are cured of the infection. However, a small number of people develop a very severe, life-threatening form of acute hepatitis called fulminant hepatitis. Chronic hepatitis B is an infection with HBV that lasts longer than 6 months. Once the infection becomes chronic, it may never go away completely. Approximately 90% to 95% of infected adults are able to fight off the virus so their infection is cured. Only about 5% to 10% of adults infected with HBV go on to develop chronic infection. About two-thirds of people with chronic HBV infection are chronic carriers. These people do not develop symptoms, even though they harbor the virus and can transmit it to other people. The remaining one third develops "active" hepatitis, a disease of the liver that can be very serious.The liver is an important organ that filters toxins out of the blood, stores energy for later use, helps with digestion, and makes substances that fight infections and control bleeding. The liver has an incredible ability to heal itself, but long-term inflammation caused by HBV can result in permanent damage. Scarring of the liver is called cirrhosis, a condition traditionally associated with alcoholism but one that is also caused by chronic active hepatitis B infection. When this occurs, the liver can no longer carry out its normal functions and may fail completely. The only treatment for liver failure is liver transplant. Chronic hepatitis B also can lead to a type of liver cancer known as hepatocellular carcinoma. Any of these conditions can be fatal. About 15% to 25% percent of people with chronic hepatitis B die of liver disease. The good news is that infection with HBV is usually preventable because there is an effective vaccine.Hepatitis B can spread by blood; body fluids from the patient or virus carrier to others.Half of all people infected with the hepatitis B virus have no symptoms. Symptoms develop within 30-180 days of exposure to the virus. The symptoms are often compared to flu. Most people think they have flu and never think about having HBV infection, such as appetite loss, feeling tired (fatigue), nausea and vomiting, itching all over the body, pain over the liver (on the right side of the abdomen, under the lower rib cage), jaundice - A condition in which the skin and the whites of the eyes turn yellow in color, and the patient’s urine becomes dark in color (like cola or tea) and the stools are pale in color (grayish or clay colored)./hepatitis_b/article_em.htmCholeraCholera is an acute infectious disease caused by a bacterium,Vibrio cholerae (V. cholerae), which results in a painless, watery diarrhea in humans. Some affected individuals have copious amounts of diarrhea and develop dehydration so severe it can lead to death. Most people who get the disease ingest the organisms through food or water sources contaminated with V. cholerae. Although symptoms may be mild, approximately 5%-10% of previously healthy people will develop a copious diarrhea within about one to five days after ingesting the bacteria.The symptoms and signs of cholera are a watery diarrhea that often contains flecks of whitish material (mucus and some epithelial cells) that are about the size of pieces of rice. The diarrhea is termed "rice-water stool" and smells "fishy." People may go on to develop one or more of the following symptoms and signs: Vomiting , rapid heart rate, loss of skin elasticity, dry mucous membranes, low blood pressure, thirst, muscle cramps, restlessness or irritability (especially in children).People require immediate hydration to prevent these symptoms from continuing because these signs and symptoms indicate that the person is becoming or is dehydrated and may go on to develop severe cholera. People with severe cholera (about 5%-10% of previously healthy people; higher if a population is compromised by poor nutrition or has a high percentage of very young or elderly people) can develop severe dehydration, leading to acute renal failure, severe electrolyte imbalances (especially potassium an sodium), and coma. If untreated, this severe dehydration can rapidly lead to shock and death. Severe dehydration can often occur four to eight hours after the first liquid stool with death in about 18 hours to a few days in undertreated or untreated people. In epidemic outbreaks in underdeveloped countries where little or no treatment is available, the mortality (death) rate can be as high as 50%-60%.The prognosis (outcome) of cholera can range from excellent to poor, depending on the severity of the dehydration and how quickly the patient is given and responds to treatments. Death (mortality) rates in untreated cholera can be as high as 50%-60% during large outbreaks but can be reduced to about 1% if treatment protocols (see above treatment section) are rapidly put into action. In general, the less severe the symptoms and the less time people have dehydration symptoms, the better the prognosis; in many people, if dehydration is quickly reversed, the prognosis is often excellent.Cholera can be prevented by several methods. Developed countries have almost no incidents of cholera because they have widespread water-treatment plants, food-preparation facilities that usually practice sanitary protocols, and most people have access to toilets and hand-washing facilities. Individuals can prevent or reduce the chance they may get cholera by hand washing, avoiding areas and people with cholera, drinking treated water or similar safe fluids and eating cleaned and well-cooked food. In addition, there are vaccines available that can help prevent cholera. Some physicians feel that foreign travelers almost never contract cholera and that use of the current vaccine cannot be justified./cholera/article.htmCholera is a bacterial disease that affects the intestinal tract. It is caused by a germ called Vibrio cholerae. The cholera germ is passed in the stools. It is spread by eating or drinking food or water contaminated by the fecal waste of an infected person. This occurs more often in underdeveloped countries lacking adequate water supplies and proper sewage disposal.People who consume raw or undercooked seafood from warm coastal waters subject to sewage contamination are at a high risk to be affected. People exposed to cholera may experience mild to severe diarrhea, vomiting and dehydration, and the symptoms may appear from a few hours to five days after exposure.Because of the rapid dehydration that may result from severe diarrhea, replacement of fluids by mouth or by the intravenous route is critical. Antibiotics, such as tetracycline, are also used to shorten the duration of diarrhea and shedding of the germs in the feces. A vaccine is available and is sometimes recommended for travelers to certain foreign countries where cholera is occurring. However, the vaccine offers only partial protection (50 percent) for a short duration (two to six months). The single most important preventive measure is to avoid consuming uncooked foods or water in foreign countries where cholera occurs unless they are known to be safe or have been properly treated./diseases/communicable/cholera/fact_sheet.htm。