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Tetanus http://www.mayoclinic.org/diseases-conditions/tetanus/basics/definition/con-20021956 Definition By Mayo Clinic Staff Tetanus is a serious bacterial disease that affects your nervous system, leading to painful muscle contractions, particularly of your jaw and neck muscles. Tetanus can interfere with your ability to breathe and, ultimately, threaten your life. Tetanus is commonly known as "lockjaw." Thanks to the tetanus vaccine, cases of tetanus are rare in the United States and the developed world. The incidence of tetanus is much higher in less developed countries. Around a million cases occur worldwide each year. There's no cure for tetanus. Treatment focuses on managing complications until the effects of the tetanus toxin resolve. Fatality is highest in individuals who haven't been immunized and in older adults with inadequate immunization. Symptoms By Mayo Clinic Staff Signs and symptoms of tetanus may appear anytime from a few days to several weeks after tetanus bacteria enter your body through a wound. The average incubation period is seven to eight days. Common signs and symptoms of tetanus, in order of appearance, are: Spasms and stiffness in your jaw muscles Stiffness of your neck muscles Difficulty swallowing Stiffness of your abdominal muscles Painful body spasms lasting for several minutes, typically triggered by minor occurrences, such as a draft, loud noise, physical touch or light Other signs and symptoms may include: Fever Sweating Elevated blood pressure Rapid heart rate Causes By Mayo Clinic Staff The bacteria that cause tetanus, Clostridium tetani, are found in soil, dust and animal feces. When they enter a deep flesh wound, spores of the bacteria may produce a powerful toxin, tetanospasmin, which actively impairs your motor neurons, nerves that control your muscles. The effect of the toxin on your motor neurons can cause muscle stiffness and spasms — the major signs of tetanus. Risk factors By Mayo Clinic Staff In addition, certain factors are necessary for tetanus bacteria to proliferate in your body. These include: Lack of immunization or inadequate immunization — failure to receive timely booster shots — against tetanus A penetrating injury that results in tetanus spores being introduced to the wound site The presence of other infective bacteria Injured tissue A foreign body, such as a nail or splinter Swelling around the injury Tetanus cases have developed from the following types of injuries: Puncture wounds — including from splinters, body piercings, tattoos, injection drugs Gunshot wounds Compound fractures Crush injuries Burns Surgical wounds Injection drug use Ear infections Animal bites Infected foot ulcers Infected umbilical stumps in newborns born of inadequately immunized mothers Complications By Mayo Clinic Staff Once tetanus toxin has bonded to your nerve endings it is impossible to remove. Complete recovery from a tetanus infection requires the growth of new nerve endings and can take up to several months. Complications of tetanus infection may include: Broken bones. The severity of spasms may cause the spine and other bones to break. Disability. Treatment for tetanus typically involves the use of powerful sedatives to control muscle spasms. Prolonged immobility due to the use of these drugs can lead to permanent disability. In infants, tetanus infections may cause lasting brain damage, ranging from minor mental deficits to cerebral palsy. Death. Severe tetanus-induced (tetanic) muscle spasms can interfere with your breathing, causing periods in which you can't breathe at all. Respiratory failure is the most common cause of death. Lack of oxygen may also induce cardiac arrest and death. Pneumonia is another cause of death. Typhoid http://www.mayoclinic.org/diseases-conditions/typhoid-fever/basics/definition/con-20028553 Definition By Mayo Clinic Staff Typhoid fever is caused by Salmonella typhi bacteria. Typhoid fever is rare in industrialized countries. However, it remains a serious health threat in the developing world, especially for children. Typhoid fever spreads through contaminated food and water or through close contact with someone who's infected. Signs and symptoms usually include high fever, headache, abdominal pain, and either constipation or diarrhea. When treated with antibiotics, most people with typhoid fever feel better within a few days, although a small percentage of them may die of complications. Vaccines against typhoid fever are available, but they're only partially effective. Vaccines usually are reserved for those who may be exposed to the disease or are traveling to areas where typhoid fever is common. Symptoms By Mayo Clinic Staff Although children with typhoid fever sometimes become sick suddenly, signs and symptoms are more likely to develop gradually — often appearing one to three weeks after exposure to the disease. 1st week of illness Once signs and symptoms do appear, you're likely to experience: Fever, that starts low and increases daily, often to as high as 103 or 104 F (39.4 or 40 C) Headache Weakness and fatigue Dry cough Loss of appetite Abdominal pain Diarrhea or constipation Rash 2nd week of illness If you don't receive treatment for typhoid fever, you may enter a second stage during which you become very ill and experience: Continuing high fever Either diarrhea or severe constipation Considerable weight loss Extremely distended abdomen 3rd week of illness By the third week, you may: Become delirious Lie motionless and exhausted with your eyes half-closed in what's known as the typhoid state Life-threatening complications often develop at this time. 4th week of illness Improvement may come slowly during the fourth week. Your fever is likely to decrease gradually until your temperature returns to normal in another week to 10 days. But signs and symptoms can return up to two weeks after your fever has subsided. Causes By Mayo Clinic Staff Typhoid fever is caused by a virulent bacterium called Salmonella typhi. Although they're related, S. typhi and the bacterium responsible for salmonellosis, another serious intestinal infection, aren't the same. Fecal-oral transmission route The bacteria that cause typhoid fever spread through contaminated food or water and occasionally through direct contact with someone who is infected. In developing nations, where typhoid is endemic, most cases result from contaminated drinking water and poor sanitation. The majority of people in industrialized countries pick up the typhoid bacteria while traveling and spread it to others through the fecal-oral route. This means that S. typhi is passed in the feces and sometimes in the urine of infected people. You can contract the infection if you eat food handled by someone with typhoid fever who hasn't washed carefully after using the toilet. You can also become infected by drinking water contaminated with the bacteria. Typhoid carriers Even after treatment with antibiotics, a small number of people who recover from typhoid fever continue to harbor the bacteria in their intestinal tracts or gallbladders, often for years. These people, called chronic carriers, shed the bacteria in their feces and are capable of infecting others, although they no longer have signs or symptoms of the disease themselves. Risk factors By Mayo Clinic Staff Typhoid fever remains a serious worldwide threat — especially in the developing world — affecting an estimated 22 million people each year, according to the Centers for Disease Control and Prevention. The disease is endemic in India, Southeast Asia, Africa, South America and many other areas. Worldwide, children are at greatest risk of getting the disease, although they generally have milder symptoms than adults do. If you live in a country where typhoid fever is rare, you're at increased risk if you: Work in or travel to areas where typhoid fever is endemic Work as a clinical microbiologist handling Salmonella typhi bacteria Have close contact with someone who is infected or has recently been infected with typhoid fever Have an immune system weakened by medications such as corticosteroids or diseases such as HIV/AIDS Drink water contaminated by sewage that contains S. typhi Complications By Mayo Clinic Staff Intestinal bleeding or holes The most serious complication of typhoid fever — intestinal bleeding or holes (perforations) — may develop in the third week of illness. About 5 percent of people with typhoid fever experience this complication. Intestinal bleeding is often marked by a sudden drop in blood pressure and shock, followed by the appearance of blood in your stool. A perforated intestine occurs when your small intestine or large bowel develops a hole, causing intestinal contents to leak into your abdominal cavity and triggering signs and symptoms such as severe abdominal pain, nausea, vomiting and bloodstream infection (sepsis). This life-threatening emergency requires immediate medical care. Other, less common complications Other possible complications include: Inflammation of the heart muscle (myocarditis) Inflammation of the lining of the heart and valves (endocarditis) Pneumonia Inflammation of the pancreas (pancreatitis) Inflammation of the gallbladder (cholecystitis) Kidney or bladder infections Infection and inflammation of the membranes and fluid surrounding your brain and spinal cord (meningitis) Psychiatric problems such as delirium, hallucinations and paranoid psychosis With prompt treatment, nearly all people in industrialized nations recover from typhoid. Without treatment, some people may not survive complications of the disease. Tuberculosis http://www.mayoclinic.org/diseases-conditions/tuberculosis/basics/definition/con-20021761 Definition By Mayo Clinic Staff Tuberculosis (TB) is a potentially serious infectious disease that mainly affects your lungs. The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes. Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person's immune system so it can't fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993, but remains a concern. Many strains of tuberculosis resist the drugs most used to treat the disease. People with active tuberculosis must take several types of medications for many months to eradicate the infection and prevent development of antibiotic resistance. Symptoms By Mayo Clinic Staff Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between: Latent TB. In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn't contagious. It can turn into active TB, so treatment is important for the person with latent TB and to help control the spread of TB in general. An estimated 2 billion people have latent TB. Active TB. This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later. Signs and symptoms of active TB include: Coughing that lasts three or more weeks Coughing up blood Chest pain, or pain with breathing or coughing Unintentional weight loss Fatigue Fever Night sweats Chills Loss of appetite Tuberculosis can also affect other parts of your body, including your kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine may give you back pain, and tuberculosis in your kidneys might cause blood in your urine. Causes By Mayo Clinic Staff Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings. Although tuberculosis is contagious, it's not easy to catch. You're much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who've had appropriate drug treatment for at least two weeks are no longer contagious. HIV and TB Since the 1980s, the number of cases of tuberculosis has increased dramatically because of the spread of HIV, the virus that causes AIDS. Infection with HIV suppresses the immune system, making it difficult for the body to control TB bacteria. As a result, people with HIV are many times more likely to get TB and to progress from latent to active disease than are people who aren't HIV positive. Drug-resistant TB Another reason tuberculosis remains a major killer is the increase in drug-resistant strains of the bacterium. Since the first antibiotics were used to fight tuberculosis 60 years ago, some TB germs have developed the ability to survive, and that ability gets passed on to their descendants. Drug-resistant strains of tuberculosis emerge when an antibiotic fails to kill all of the bacteria it targets. The surviving bacteria become resistant to that particular drug and frequently other antibiotics as well. Some TB bacteria have developed resistance to the most commonly used treatments, such as isoniazid and rifampin. Some strains of TB have also developed resistance to drugs less commonly used in TB treatment, such as the antibiotics known as fluoroquinolones, and injectable medications including amikacin, kanamycin and capreomycin. These medications are often used to treat infections that are resistant to the more commonly used drugs. Risk factors By Mayo Clinic Staff Anyone can get tuberculosis, but certain factors can increase your risk of the disease. These factors include: Weakened immune system A healthy immune system often successfully fights TB bacteria, but your body can't mount an effective defense if your resistance is low. A number of diseases and medications can weaken your immune system, including: HIV/AIDS Diabetes End-stage kidney disease Certain cancers Cancer treatment, such as chemotherapy Drugs to prevent rejection of transplanted organs Some drugs used to treat rheumatoid arthritis, Crohn's disease and psoriasis Malnutrition Very young or advanced age Traveling or living in certain areas The risk of contracting tuberculosis is higher for people who live in or travel to countries that have high rates of tuberculosis and drug-resistant tuberculosis, such as: Sub-Saharan Africa India China Russia Pakistan Poverty and substance abuse Lack of medical care. If you receive a low or fixed income, live in a remote area, have recently immigrated to the United States, or are homeless, you may lack access to the medical care needed to diagnose and treat TB. Substance abuse. IV drug use or alcohol abuse weakens your immune system and makes you more vulnerable to tuberculosis. Tobacco use. Using tobacco greatly increases the risk of getting TB and dying of it. Where you work or live Health care work. Regular contact with people who are ill increases your chances of exposure to TB bacteria. Wearing a mask and frequent hand-washing greatly reduce your risk. Living or working in a residential care facility. People who live or work in prisons, immigration centers or nursing homes are all at a higher risk of tuberculosis. That's because the risk of the disease is higher anywhere there is overcrowding and poor ventilation. Living in a refugee camp or shelter. Weakened by poor nutrition and ill health and living in crowded, unsanitary conditions, refugees are at especially high risk of tuberculosis infection. Complications By Mayo Clinic Staff Without treatment, tuberculosis can be fatal. Untreated active disease typically affects your lungs, but it can spread to other parts of the body through your bloodstream. Examples of tuberculosis complications include: Spinal pain. Back pain and stiffness are common complications of tuberculosis. Joint damage. Tuberculous arthritis usually affects the hips and knees. Swelling of the membranes that cover your brain (meningitis). This can cause a lasting or intermittent headache that occurs for weeks. Mental changes also are possible. Liver or kidney problems. Your liver and kidneys help filter waste and impurities from your bloodstream. These functions become impaired if the liver or kidneys are affected by tuberculosis. Heart disorders. Rarely, tuberculosis can infect the tissues that surround your heart, causing inflammation and fluid collections that may interfere with your heart's ability to pump effectively. This condition, called cardiac tamponade, can be fatal. Polio http://www.mayoclinic.org/diseases-conditions/polio/basics/definition/con-20030957 Definition By Mayo Clinic Staff Polio is a contagious viral illness that in its most severe form causes paralysis, difficulty breathing and sometimes death. In the U.S., the last case of naturally occurring polio happened in 1979. Today, despite a concerted global eradication campaign, poliovirus continues to affect children and adults in Afghanistan, Pakistan and some African countries. The Centers for Disease Control and Prevention (CDC) advises taking precautions to protect against polio if you're traveling anywhere there's a risk of polio. If you're a previously vaccinated adult who plans to travel to an area where polio is occurring, you should receive a booster dose of inactivated poliovirus vaccine (IPV). Immunity after a booster dose lasts a lifetime. Symptoms By Mayo Clinic Staff Although polio can cause paralysis and death, the vast majority of people who are infected with the poliovirus don't become sick and are never aware they've been infected with polio. Nonparalytic polio Some people who develop symptoms from the poliovirus contract nonparalytic polio — a type of polio that doesn't lead to paralysis (abortive polio). This usually causes the same mild, flu-like signs and symptoms typical of other viral illnesses. Signs and symptoms, which generally last one to 10 days, include: Fever Sore throat Headache Vomiting Fatigue Back pain or stiffness Neck pain or stiffness Pain or stiffness in the arms or legs Muscle weakness or tenderness Meningitis Paralytic polio In rare cases, poliovirus infection leads to paralytic polio, the most serious form of the disease. Paralytic polio has several types, based on the part of your body that's affected — your spinal cord (spinal polio), your brainstem (bulbar polio) or both (bulbospinal polio). Initial signs and symptoms of paralytic polio, such as fever and headache, often mimic those of nonparalytic polio. Within a week, however, signs and symptoms specific to paralytic polio appear, including: Loss of reflexes Severe muscle aches or weakness Loose and floppy limbs (flaccid paralysis), often worse on one side of the body Post-polio syndrome Post-polio syndrome is a cluster of disabling signs and symptoms that affect some people several years — an average of 35 years — after they had polio. Common signs and symptoms include: Progressive muscle or joint weakness and pain General fatigue and exhaustion after minimal activity Muscle atrophy Breathing or swallowing problems Sleep-related breathing disorders, such as sleep apnea Decreased tolerance of cold temperatures Cognitive problems, such as concentration and memory difficulties Depression or mood swings Causes By Mayo Clinic Staff The poliovirus resides only in humans and enters the environment in the feces of someone who's infected. Poliovirus spreads primarily through the fecal-oral route, especially in areas where sanitation is inadequate. Poliovirus can be transmitted through contaminated water and food or through direct contact with someone infected with the virus. Polio is so contagious that anyone living with a recently infected person is likely to become infected, too. People carrying the poliovirus can spread the virus for weeks in their feces. Risk factors By Mayo Clinic Staff You're at greatest risk of polio if you haven't been immunized against the disease. In areas with poor sanitation and sporadic or nonexistent immunization programs, the most vulnerable members of the population — pregnant women, the very young and those with weakened immune systems — are especially susceptible to experience paralysis if they are infected with poliovirus. These factors also increase your risk if you haven't been vaccinated: Travel to an area where polio is common or that has recently experienced an outbreak Living with or caring for someone who may be shedding poliovirus A compromised immune system, such as occurs with HIV infection Having had your tonsils removed (tonsillectomy) Extreme stress or strenuous physical activity after being exposed to poliovirus, both of which can depress your immune system Complications By Mayo Clinic Staff Paralytic polio can lead to temporary or permanent muscle paralysis, disability, and deformities of the hips, ankles and feet. Although many deformities can be corrected with surgery and physical therapy, these treatments may not be options in developing nations where polio is still common. As a result, children who survive polio may spend their lives with severe disabilities. Mononucleosis Definition By Mayo Clinic Staff Infectious mononucleosis (mono) is often called the kissing disease. The virus that causes mono is transmitted through saliva, so you can get it through kissing, but you can also be exposed through a cough or sneeze, or by sharing a glass or food utensils with someone who has mono. However, mononucleosis isn't as contagious as some infections, such as the common cold. You're most likely to get mononucleosis with all the signs and symptoms if you're an adolescent or young adult. Young children usually have few symptoms, and the infection often goes unrecognized. If you have mononucleosis, it's important to be careful of certain complications such as an enlarged spleen. Rest and adequate fluids are key to recovery. Symptoms By Mayo Clinic Staff Signs and symptoms of mononucleosis may include: Fatigue General feeling of unwellness (malaise) Sore throat, perhaps a strep throat that doesn't get better with antibiotic use Fever Swollen lymph nodes in your neck and armpits Swollen tonsils Headache Skin rash Soft, swollen spleen The virus has an incubation period of approximately four to six weeks, although in young children this period may be shorter. Signs and symptoms such as fever and sore throat usually lessen within a couple of weeks, although fatigue, enlarged lymph nodes and a swollen spleen may last for a few weeks longer. Causes By Mayo Clinic Staff The cause of mononucleosis is the Epstein-Barr virus. Mononucleosis usually isn't very serious. Most adults have been exposed to the Epstein-Barr virus and have built up antibodies. They're immune and won't get mononucleosis again. Complications By Mayo Clinic Staff Complications of mononucleosis may be more serious than the disease itself. Enlargement of the spleen Mononucleosis may cause enlargement of the spleen. In extreme cases, your spleen may rupture, causing sharp, sudden pain in the left side of your upper abdomen. If such pain occurs, seek medical attention immediately — you may need surgery. Liver issues Problems with your liver also may occur: Hepatitis. You may experience mild liver inflammation (hepatitis). Jaundice. A yellowing of your skin and the whites of your eyes (jaundice) also occurs occasionally. Less common complications Mononucleosis can also result in the following less common complications: Anemia — a decrease in red blood cells and in hemoglobin, an iron-rich protein in red blood cells Thrombocytopenia — low count of platelets, which are blood cells involved in clotting Heart problems — an inflammation of the heart muscle (myocarditis) Complications involving the nervous system — meningitis, encephalitis and Guillain-Barre syndrome Swollen tonsils — which can block breathing The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems, such as people with HIV/AIDS or people taking drugs to suppress immunity after an organ transplant. Rabies http://www.mayoclinic.org/diseases-conditions/rabies/basics/definition/con-20019900 Definition By Mayo Clinic Staff Rabies is a deadly virus spread to people from the saliva of infected animals. The rabies virus is usually transmitted through a bite. Animals most likely to transmit rabies in the United States include bats, coyotes, foxes, raccoons and skunks. In developing countries of Africa and Southeast Asia, stray dogs are the most likely to spread rabies to people. Once a person begins showing signs and symptoms of rabies, the disease is nearly always fatal. For this reason, anyone who may have a risk of contracting rabies should receive rabies vaccines for protection. Symptoms By Mayo Clinic Staff The first symptoms of rabies may be very similar to the flu and may last for days. Signs and symptoms may include: Fever Headache Nausea Vomiting Agitation Anxiety Confusion Hyperactivity Difficulty swallowing Excessive salivation Fear of water (hydrophobia) because of the difficulty in swallowing Hallucinations Insomnia Partial paralysis When to see a doctor Seek immediate medical care if you're bitten by any animal. Based on your injuries and the situation in which the bite occurred, you and your doctor can decide whether you should receive treatment to prevent rabies. Even if you aren't sure whether you've been bitten, seek medical attention. For instance, a bat that flies into your room while you're sleeping may bite you without waking you. If you awake to find a bat in your room, assume you've been bitten. Also, if you find a bat near a person who can't report a bite, such as a small child or a person with a disability, assume that person has been bitten. Causes By Mayo Clinic Staff Rabies infection is caused by the rabies virus. The virus is spread through the saliva of infected animals. Infected animals can spread the virus by biting another animal or a person. In rare cases, rabies can be spread when infected saliva gets into an open wound or the mucous membranes, such as the mouth or eyes. This could occur if an infected animal were to lick an open cut on your skin. Animals that can transmit the rabies virus Any mammal (an animal that suckles its young) can transmit the rabies virus. The animals most likely to transmit the rabies virus to people include: Pets and farm animals Cats Cows Dogs Ferrets Goats Horses Wild animals Bats Beavers Coyotes Foxes Monkeys Raccoons Skunks Woodchucks In rare cases, the virus has been transmitted to tissue and organ transplant recipients from an infected organ. Risk factors By Mayo Clinic Staff Factors that can increase your risk of rabies include: Traveling or living in developing countries where rabies is more common, including countries in Africa and Southeast Asia Activities that are likely to put you in contact with wild animals that may have rabies, such as exploring caves where bats live or camping without taking precautions to keep wild animals away from your campsite Working in a laboratory with the rabies virus Wounds to the head, neck or hands, which may help the rabies virus travel to your brain more quickly