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Viruses

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Related Terms
  • Acute viral nasopharyngitis, antibody, antibody test, antiretrovirals, antiviral, antivirals, common cold, Epstein-Barr virus, flu, flu shot, flu vaccine, HAART, hepatitis, hepatitis A, hepatitis B, highly active antiretroviral therapy, HIV, human immunodeficiency virus, immunomodulators, infection, influenza, immunization, interferons, measles, MMR, molluscum contagiosum, mumps, uncoating, replication, rubella, vaccination, vaccine, viral, viral particles, virus.

Background
  • A viral infection occurs when tiny disease-causing particles, called a virus, enter the body and begin multiplying. More than 400 different viruses are known to cause infections in humans.
  • Once a virus enters the body, it uses the host's cells to reproduce. In some cases, the infected cell is destroyed during this process. Once the virus multiplies, new viral particles are released into the body that can infect more cells. As the virus takes control over certain cells, the person starts to become sick. Symptoms vary depending on the specific type and number of cells that become infected.
  • Some viruses, such as the human papilloma virus (HPV), do not kill the cells they infect. Instead, some viruses may just change the host cell's functions. For instance, some cells may begin to multiply and divide abnormally, which may lead to cancerous growths. Other viruses may insert their genetic material (DNA) into a human cell where it remains dormant (latent) for a period of time. When the cell is disturbed, it may stimulate the virus to start multiplying, which causes an illness.
  • Most viruses infect specific types of cells in the body. For instance, the human immunodeficiency virus (HIV) primarily attacks immune cells called CD4 cells. Because the CD4 cells fight against disease and infection, the virus weakens the patient's immune system.
  • Viral infections can affect most parts of the body, including the liver, immune system, and skin. The severity of a viral infection depends on the specific type of infection. Some viruses, such as the common cold, may cause mild symptoms that go away on their own in a few days. Other viral infections, such as hepatitis, may be life threatening.
  • Mild viral infections usually do not require treatment. Some patients with the common cold or flu may benefit from medications, such as nasal decongestants, to treat the symptoms. More severe viral infections, such as hepatitis, may require medications such as antivirals or immunomodulators to destroy the virus. Not all viral infections are curable. For instance, HIV is a lifelong condition that eventually leads to death. However, HIV treatment, called antiretroviral therapy, delays the progression of the disease by limiting the virus's ability to multiply in the body. As a result, less HIV is present in the blood.
  • Many types of viral infections can be prevented with vaccinations, also called immunizations. Patients can receive vaccinations to prevent hepatitis A, hepatitis B, influenza, as well as the measles, mumps, and rubella (MMR).

Signs and symptoms
  • General: In general, most viral infections cause fever and a general feeling of discomfort. Additional symptoms depend on the type and severity of the infection.
  • Common cold: A common cold may cause symptoms such as runny or stuffy nose, itchy or sore throat, dry cough, facial pressure due to sinuses (hollow bones in the front of the face), slight body aches or mild headaches, sneezing, itchy watery eyes, low-grade fever (less than 102 degrees Fahrenheit), and mild fatigue (tiredness). Symptoms generally resolve on their own in about one week.
  • Hepatitis A: Most patients with hepatitis A experience mild, if any, symptoms. Symptoms usually do not develop until about four weeks after exposure to the virus. Symptoms may include nausea, vomiting, fatigue, decreased appetite, low-grade fever, muscle pain, itchy skin, yellowing of the eyes and skin (called jaundice), and dark urine. Symptoms usually resolve after one to two months. In some patients, symptoms may return over a six to nine month period.
  • Hepatitis B: Patients with hepatitis B are more likely to develop symptoms than patients with hepatitis A. Symptoms may develop anywhere from six weeks to six months after exposure to the virus. Symptoms may include abdominal pain (especially near the liver), dark urine, yellowing of the skin and eyes (jaundice), and blood in the urine. The infection usually lasts about three weeks. However, some patients may develop long-term infections.
  • Human immunodeficiency virus (HIV): One to two months after becoming infected, nearly all HIV patients develop flu-like symptoms that last about one week. For the next several months or years, patients usually do not experience any symptoms of the disease. Once this asymptomatic period ends, symptoms may include enlarged lymph nodes, fatigue, weight loss, frequent fevers and sweats, persistent or frequent yeast infections of the mouth or vagina, persistent skin rashes, flaky skin, pelvic inflammatory disease (PID) in women, and short-term memory loss. As the immune system continues to weaken, patients eventually progress to the acquired immunodeficiency syndrome (AIDS). During this stage, patients have the greatest risk of developing life-threatening diseases and infections.
  • Influenza (flu): Symptoms of influenza (flu) usually appear suddenly and may include fevers of 101 degrees Fahrenheit or higher, cough, muscle aches and pains, headache, sore throat, chills and sweats, loss of appetite, fatigue, and a general feeling of discomfort. The fever and body aches can last three to five days, and the cough and lack of energy may last for two weeks or more. In addition, children may experience vomiting and diarrhea with the flu, which are rare in adults. In severe cases, influenza may be fatal. This is most likely to occur in children, the elderly, and in patients with weakened immune systems.
  • Mononucleosis (mono): Symptoms of mononucleosis usually develop four to six weeks after exposure. Symptoms may include fatigue (which may be severe and limit daily activities), sore throat, enlarged lymph nodes, fever, headache, swollen tonsils, loss of appetite, skin rash, soft and swollen spleen, and night sweats. Symptoms, such as sore throat and fever, usually start to improve after a couple weeks. However, fatigue, swollen spleen, and enlarged lymph nodes may last for a few weeks longer.
  • Measles, mumps, and rubella: Measles is a virus that causes a rash, cough, runny nose, eye irritation, and fever in most patients. In severe cases, patients may develop pneumonia, seizures, brain damage, and death. The mumps virus typically causes fever, headache, and swollen glands. In severe cases, the mumps may lead to deafness, infection of the membranes that surround the brain and spinal cord (meningitis), swollen testicles or ovaries, and death. Rubella is generally a mild disease. However, it may cause serious birth defects in newborns if a pregnant mother becomes infected. Molluscum contagiosum: Symptoms of molluscum contagiosum include round bumps (papules) on the skin that may be red and swollen. Although scratching removes the bumps, it also spreads the virus to nearby areas of skin. In children, bumps usually develop on the face, hands, arms, armpits, and neck. In adults, the infection is more likely to affect the genitals, inner upper thighs, buttocks, and lower abdomen.

Diagnosis
  • General: Common viral infections, such as the common cold or influenza (flu), may be diagnosed after a medical history and physical examination. Tests may also be performed to detect the presence of the virus or antibodies to the virus.
  • Antibody test: Most viral infections are diagnosed after an antibody test. This test determines if the patient has developed antibodies to a particular virus. Antibodies are proteins that are specialized to help the immune system fight against specific foreign invaders. During the procedure, a sample of blood, urine, or oral fluid (not saliva) from the patient's gums is taken. The sample is sent to a laboratory for testing. If antibodies are present, then a positive diagnosis is made.
  • Antigen-detection test: Unlike the antibody test, an antigen-detection test can be used to diagnose an infection before the patient has had time to develop antibodies. However, this test is much more expensive than an antibody test and it is performed less often. This test can determine if a virus is present in the body. During the procedure, a sample of blood is taken or the nose or throat is swabbed. The sample is sent to a laboratory for testing. Results are usually available within 30 minutes. If a virus is present, then a positive diagnosis is made.

Treatment
  • General: The body's own immune system is able to effectively fight against most viral infections. Fluids, rest, and proper nutrition can help increase the body's ability to fight against viral infections. Additional medications are available to help reduce the symptoms of viral infections.
  • Some infections, such as hepatitis or serious cases of the flu, may be treated with medications called antivirals. These medications either enhance the body's ability to fight against the virus or limit the virus' ability to multiply. If symptoms of the viral infection worsen, then individuals should consult their healthcare providers.
  • Antivirals: Antivirals are medications that are used to treat some types of viral infections. These medications may reduce the severity of the infection and make patients less contagious. Many antivirals drugs work by disrupting the virus' ability to replicate. These medications are most effective if taken within the first few days of infection. Antivirals may be taken by mouth, applied to the skin, or injected.
  • For instance, antivirals, including amantadine (Symmetrel®), rimantadine (Flumadine®), zanamavir (Relenza®, inhaled), and oseltamivir (Tamiflu®), have been approved by the U.S. Food and Drug Administration (FDA) for the treatment and prevention of influenza. Antivirals, such as lamivudine (Epivir-HBV®), adefovir dipivoxil (Hepsera®), and entecavir (Baraclude®), are commonly used to treat hepatitis. In general, side effects of antivirals may include dizziness, nausea, vomiting, loss of appetite, and difficulty breathing.
  • Antiretrovirals: Antiretrovirals are a type of antivirals that disrupt the virus's ability to multiply. A combination of antiretrovirals, called highly active antiretroviral therapy (HAART), is used to treat HIV patients because a single patient may have several different strains (types) of the virus circulating in the blood. The different strains of the virus may respond differently to specific types of drugs. In addition, HAART helps reduce the number of viral mutations inside the body, including those that may be resistant to medications.
  • HAART involves a combination of drugs from at least two different drug classes. There are four major classes of antiretrovirals: fusion inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors. Each drug class disrupts different stages of HIV's life cycle.
  • HAART has been shown to suppress the amount of HIV in the body and subsequently boost the body's immune system. As a result, patients are less likely to become sick with potentially fatal diseases and infections.
  • Individuals taking antiretroviral drugs often have a difficult time following complicated drug plans. Also, some of the drugs require not eating before or after taking them and may cause side effects such as nausea and vomiting. Other antiretroviral drugs may cause serious medical problems, including changes in body fat distribution, increased lipid (fat) levels in the blood, and changes in glucose (sugar) metabolism. Changes in glucose metabolism may lead to the onset or worsening of diabetes.
  • Interferons: The body naturally produces interferons to fight against invading organisms, including viruses. Administering additional man-made interferons may stimulate the body's immune response to hepatitis and help prevent the virus from spreading. Two interferon medications are available for the treatment of hepatitis: interferon alfa-2b (Intron A®) and peginterferon alfa-2a (Pegasys®). Intron A® is administered by injection several times a week. Pegasys® is given by injection once a week.
  • Not everyone is a candidate for interferon treatment. In a few cases, interferon has successfully eliminated the virus completely. However, the infection can return in the future. Several side effects are associated with interferon, including depression, fatigue, muscle pain, body aches, fever, and nausea. Interferon may also cause a decreased production of red blood cells. Symptoms are usually worse during the first two weeks of treatment and during the first four to six hours after receiving an injection of interferon.
  • Cough syrups: Nonprescription cough syrups that contain various combinations of antihistamines, decongestants, and cough suppressants are available over-the-counter (OTC) for symptomatic relief of cough. Many doctors strongly discourage the use of these combination medications for any child younger than age two in whom accidental overdoses could be fatal. Coughs associated with the flu usually last less than two to three weeks. If a cough lasts longer than three weeks, then a doctor should be seen. If the cough brings up mucus, then medications containing guaifenesin (e.g. Brontex® or Mucinex®) may help break up the chest congestion. If the cough is dry and hacking, then a cough suppressant, such as dextromethorphan (e.g. Delsym®, Robitussin®, or Vicks® 44 Cough Relief), may stop the cough.
  • Lozenges and sprays: Sore throat caused by the flu may be self-treated if the pain is minor. Healthcare professionals recommend not self-treating sore throat for more than two days. Lozenges for sore throat contain active ingredients such as the anesthetics benzocaine, menthol, dyclonine, phenol/sodium phenolate, and hexylresorcinol.
  • Nasal decongestants: Nasal decongestants are useful medications for nasal symptoms, such as stuffy nose, associated with viral infections that affect the respiratory tract. These drugs shrink the tissues and blood vessels in the eyes and nose that swell in response to a cold. As a result, symptoms of stuffiness are improved. Nasal decongestants are available as tablets, sprays, inhalers, and nose drops. Nasal decongestants include oral decongestants, such as pseudoephedrine (Sudafed®); nasal sprays, such as oxymetazoline (Afrin®) and phenylephrine (Neo-Synephrine®); and nasal inhalers, such as propylhexedrine (Benzedrex®) and levmetamfetamine (Vicks Vapor Inhaler®). These are safe for most patients, but patients should be aware of the many possible side effects as well as conditions with which the medications should not be used. People with heart disease, high blood pressure, thyroid disease, glaucoma (increased pressure in the eyes), diabetes, seizure disorders, enlarged prostate, and individuals using monoamine oxidase inhibitors (a type of a rarely prescribed antidepressant or Parkinson's disease medication) should consult a qualified healthcare professional before taking any medications. Stinging, burning, sneezing, increased nasal discharge, drying of the nostrils, and altered taste may occur. If these effects continue or become bothersome, patients should inform a doctor. Other side effects may include rapid or pounding heartbeat, dizziness, trouble sleeping, shaking of the hands, and tremors. Healthcare professionals recommend not using decongestants while pregnant or breastfeeding.
  • Nasal spray decongestants, such as oxymetazoline (Afrin®), should not be used more than twice daily for three consecutive days because rebound nasal congestion (significant return of stuffy nose) may occur.
  • Pseudoephedrine, once a common ingredient in over-the-counter decongestants, is only available behind-the-counter after talking with a pharmacist in many states. This is because there have been an increasing number of reports of people using pseudoephedrine to make illicit methamphetamine. Several states, including Alabama, California, Colorado, Connecticut, Delaware, Georgia, Florida, Illinois, Indiana, Iowa, Kansas, Massachusetts, Minnesota, Missouri, Montana, New Jersey, New York, North Carolina, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Virginia, and Washington have laws that require pharmacies to only sell pseudoephedrine behind-the-counter and they must also record personal information about the consumer. In July 2006, Oregon passed a law that recognizes pseudoephedrine and all products containing pseudoephedrine as a Schedule III controlled substance. Therefore, consumers in Oregon need a prescription to purchase products containing pseudoephedrine. As a result, an increasing number of manufacturers are beginning to use phenylephrine as an alternative to pseudoephedrine in their over-the-counter preparations, such as Sudafed PE®.
  • Pain relievers and fever reducers: For fever, sore throat, body aches, and headache, acetaminophen (Tylenol®) or ibuprofen (Advil® or Motrin®) may be used over-the-counter. Acetaminophen may cause liver damage, especially if taken long term or in doses that exceed 4 grams daily in adults. Individuals should carefully follow dosing guidelines when giving acetaminophen to children because children are more likely to experience serious effects from high doses. Pediatric doses vary depending on the child's age and weight. Also, parents or caregivers should not give aspirin to children younger than 18 years old. Aspirin may play a role in causing Reye's syndrome, a rare but potentially fatal illness in children.

Integrative therapies
  • Strong scientific evidence:
  • Vitamin A: Vitamin A is a fat-soluble vitamin. Vitamin A should be administered to children diagnosed with measles in areas where vitamin A deficiency may be present. Measles is a viral disease that can lead to serious complications such as diarrhea, pneumonia, and encephalitis. Supplementation with vitamin A in children with measles has been shown to be beneficial by decreasing the length and impact of the disease. Symptoms of the measles, such as diarrhea, pneumonia, and death, have been reduced with the use of vitamin A. Management of measles should be under strict medical supervision.
  • Avoid if allergic or hypersensitive to vitamin A. Vitamin A toxicity can occur if taken at high dosages. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may have an increased risk of developing lung cancer or heart disease. Vitamin A appears safe in pregnant women if taken at recommended doses. The recommended daily dose is 770 micrograms for pregnant women older than 19 years of age and 750 micrograms for pregnant women who are between 14 and 18 years old. The recommended daily dose is 1,300 micrograms for breastfeeding women who are older than 19 years of age and 1,200 micrograms for breastfeeding women who are between 14 and 18 years old. Use cautiously if breastfeeding because the benefits or dangers to nursing infants are not clearly established.
  • Unclear or conflicting scientific evidence:
  • Alizarin: Alizarin is a chemical stain that highlights calcium. Historically, alizarin has been used as an antiviral agent. There is limited scientific evidence that alizarin may help treat herpes viral infections. Further research is needed to determine if alizarin is an effective treatment for viral infections.
  • Avoid if allergic to alizarin or any plants in the Rubiaceae family. Alizarin may be toxic and should not be handled for long periods of time, rubbed in the eyes, or eaten. Avoid if pregnant or breastfeeding.
  • Astragalus: Astragalus is an extremely versatile herb that may help boost the body's immune system. Anti-viral activity has been reported with the use of astragalus in laboratory and animal studies. Limited human research has examined the use of astragalus for viral infections in the lung, heart (pericarditis, myocarditis, endocarditis), liver (hepatitis B and C), cervix (papilloma virus), and in HIV infection. Studies have included combinations of astragalus with the drug interferon or as a part of herbal mixtures. However, most studies have been small and poorly designed. Due to a lack of well-designed research, no firm conclusions can be drawn.
  • Avoid if allergic to astragalus, peas, or any other related plants or with a history of Quillaja bark-induced asthma. Avoid with aspirin, aspirin products, or herbs or supplements with similar effects. Avoid with inflammation, fever, stroke, transplant, or autoimmune diseases. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Use cautiously with bleeding disorders, diabetes, high blood pressure, lipid disorders, or kidney disorders. Use cautiously if taking blood-thinners (e.g. warfarin or aspirin), blood sugar drugs, diuretics, or herbs or supplements with similar effects. Avoid if pregnant or breastfeeding.
  • Blessed thistle: Blessed thistle is an herb that is usually found in subtropical regions of the world. Laboratory studies report no activity of blessed thistle against herpes viruses, influenza, or poliovirus. Effects of blessed thistle (or chemicals in blessed thistle called lignans) against HIV are unclear. Human research with blessed thistle as a treatment for viral infections is lacking.
  • Avoid if allergic to blessed thistle, mugwort, bitter weed, blanket flower, chrysanthemum, coltsfoot, daisy, dandelion, dwarf sunflower, goldenrod, marigold, prairie sage, ragweed, Echinacea, or any plants of the Asteraceae or Compositae families. Avoid with a history of bleeding diseases or gastroesophageal reflux disease (GERD). Avoid if taking anticoagulants (blood thinners) or drugs used to treat stroke, stomach diseases, or to control stomach acid. Avoid if pregnant or breastfeeding. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks.
  • Cranberry: Cranberries come from small evergreen shrubs with tart, red, edible berries. The berries are used in sauces, jellies, and drinks. Limited laboratory research has examined the antiviral activity of cranberries. There are no reliable human studies supporting the use of cranberries in this area.
  • Avoid if allergic to cranberries, blueberries, or other plants of the Vaccinium species. Sweetened cranberry juice can affect blood sugar levels. Use cautiously with a history of kidney stones. Avoid eating more than the amount usually found in foods if pregnant or breastfeeding.
  • Focusing: Focusing (experiential therapy) is a method of psychotherapy that involves being aware of one's feelings surrounding a particular issue and understanding the meaning behind words or images conveyed by those feelings. One study suggests that increased experiential involvement (an indication of focusing taking place) had no effect on the amount of antibodies found in a patient's blood to Epstein-Barr virus. More clinical trials in the area of immune function and antibody production are required before recommendations can be made.
  • Side effect reporting is rare, but patients should consult with their qualified healthcare practitioners before making decisions about medical conditions and practices. Individuals with severe emotional difficulties should not abandon proven medical and psychological therapies but rather choose focusing as a possible adjunct.
  • L-carnitine: L-carnitine is an amino acid that is found in almost all cells in the human body. Early studies suggest that carnitine may be beneficial for patients with diphtheria, mainly in terms of myocardial (heart) damage. However, additional study is needed to confirm these findings.
  • Avoid with known allergy or hypersensitivity to carnitine. Use cautiously with peripheral vascular disease, hypertension (high blood pressure), alcohol-induced liver cirrhosis, and diabetes. Use cautiously in low birth weight infants and individuals on hemodialysis. Use cautiously if taking anticoagulants (blood thinners), beta-blockers, or calcium channel blockers. Avoid if pregnant or breastfeeding.
  • Sorrel: Sorrel has been used as a salad green, spring tonic, diarrhea remedy, weak diuretic, and as a soothing agent for sore noses. One laboratory study suggests that sorrel may not posses any antiviral activity. However, further research is needed before a firm conclusion can be made in this area.
  • Avoid if allergic to sorrel or any member of the Rumex acetosa or Polygonaceae plant families. Avoid large doses of sorrel because there have been reports of toxicity and death, possibly caused by oxalate found in sorrel. Fatal oxalic acid poisoning has been reported from sorrel soup. Be aware that many tinctures contain high levels of alcohol and should be avoided when driving or operating heavy machinery. These sorrel formulations may cause nausea or vomiting when taken with the prescription drugs metronidazole (Flagyl®) or disulfiram (Antabuse®). Avoid if pregnant or breastfeeding.

Prevention
  • General: Vaccines can be used to prevent many types of viral infections. Vaccines work by stimulating the body's immune system. Vaccines for viral infections contain small amounts of killed or weakened viruses. This allows the immune system to produce antibodies to the foreign invader. Once antibodies are developed, the immune system is able to respond quickly to the infection if the virus enters the body. As a result, individuals become immune to the specific illness after receiving a vaccine. Some vaccines require more than one shot to take effect.
  • Hepatitis A virus (HAV): The hepatitis A virus (HAV) vaccine is recommended for all children who are one year old, all people who are traveling to areas where HAV is prevalent (e.g. Sub-Saharan Africa), children and adolescents who live in areas where HAV is common, men who have sex with men, injection drug users, hemophiliacs, and people with chronic liver disease (including chronic hepatitis B or C). Patients receive two shots over 12 to 18 months.
  • Hepatitis B: Hepatitis B vaccination is the best way to prevent hepatitis B infection. A hepatitis B vaccine (Engerix-B®) has been available since 1982. It is administered in a series of three shots over the course of six months. All three doses are needed for the most effective and longest lasting immunity.
  • A blood test should be performed once the immunization series is completed to check for HBV antibodies. If antibodies are present, then the individual responded to the vaccine and is immune to the virus. Additional shots may be necessary if the antibody levels are too low.
  • The vaccine provides more than 90% protection for both adults and children. The vaccine generally protects against the hepatitis B virus (HBV) for at least 15 years. Almost anyone can receive the vaccine, including infants, older adults, and those with immune deficiencies. Infants usually receive the vaccine at birth or several weeks after birth, with additional injections administered at two, four, and nine months of age.
  • In the last decade, recombinant DNA technology has been used to produce the vaccine in the United States. Rather than using the blood of infected patients, the HBV antigen used in the vaccine is produced in a laboratory.
  • Side effects tend to be mild and may include weakness, fatigue, headache, nausea, and soreness or swelling at the injection site. Although concerns have been raised that the HBV vaccine may increase the risk of autoimmune disease and sudden infant death syndrome (SIDS), studies have found no correlation.
  • Hepatitis A/hepatitis B combined vaccine (Twinrix®): The hepatitis A/hepatitis B combination vaccine (Twinrix®) is recommended for patients who require both HAV and HBV immunizations. Patients receive three shots over a one-year period. The vaccine has been shown to protect against hepatitis A for at least 20 years and hepatitis B for at least 15 years.
  • Influenza (flu): Patients may also receive the flu vaccination. This vaccination only lasts one year. It may be injected into the patient or sprayed into the nose. Research has shown that both forms of the vaccination are equally effective. A prescription is needed for both types of flu vaccines. They are available at a doctor's office or at a flu clinic in the local area.
  • The flu shot is an inactivated vaccine (containing killed virus) that is given with a needle. The flu shot is approved for use in people six months of age and older, including healthy people and people with chronic medical conditions such as diabetes, asthma, and heart disease. The flu shot is recommended in children aged six month to five years, adults that are in close contact with children aged six months to five years (such as teachers and daycare workers), people 50 years of age and older, healthcare workers, all care givers of high risk people (such as those with HIV/AIDS or cancer), and people with chronic health conditions (e.g. asthma), as well as pregnant women.
  • The best period to receive any of the influenza vaccines is soon after the vaccine becomes available in the fall of each year. Flu shots are given yearly to protect individuals against the strain of influenza that is expected or prevalent for a particular year. Occasionally, the most prevalent influenza strain is not correctly predicted and the vaccine will not offer protection against the different viral strains.
  • The nasal-spray flu vaccine (FluMist/LAIV®) is a vaccine made with live, weakened flu viruses that does not cause the flu (sometimes called LAIV for "Live Attenuated Influenza Vaccine"). The nasal flu vaccine is approved for use in healthy people five to 49 years of age who are not pregnant. Patients who have weakened immune systems (e.g. HIV patients or chemotherapy patients) should not receive the nasal spray vaccine because it contains a weakened form of the live influenza virus. Although rare, it is possible for the weakened virus to cause an infection in immunocompromised patients.
  • Healthcare professionals recommend that some individuals should not be vaccinated. They include people who have a severe allergy to chicken eggs, people who have had a severe reaction to a flu vaccination in the past, people who developed Guillain-Barré syndrome (a disorder where the immune system attacks the nervous system) within six weeks of getting an influenza vaccine previously, children younger than six months of age (influenza vaccine is not approved for use in this age group), and people who have moderate or severe illnesses or infections (e.g. strep throat or ear infections) with a fever should wait to get vaccinated until their symptoms lessen.
  • Measles, mumps, and rubella (MMR): The measles, mumps, and rubella (MMR) vaccine is a required immunization in the United States. People born before 1957 do not need to receive this vaccine. This is because people born in 1957 and before lived through several years of the measles epidemic when the first measles vaccine was not developed. Studies show that 95-98% of individuals born before 1957 are immune to measles.
  • Each component of the MMR vaccine can be administered separately to achieve adequate antibody levels. Patients will receive one or two shots, depending on how many antibodies they produce after immunization. The first shot is recommended when the patient is 12-15 months old. A second shot is usually recommended when the patient is four to six years old.
  • Good hygiene: Practicing good hygiene and regularly washing the hands with soap and water may help reduce the risk of acquiring infections. Avoiding close contact with individuals who have contagious illnesses may help reduce the risk of acquiring infections.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
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Causes
  • Depending on the specific virus, the infection may be transmitted in various ways. Many infections, such as the common cold and flu, are transmitted through airborne droplets of mucus. Some infections, such as HIV, are spread through bodily fluids (e.g. blood, semen, vaginal discharge, and breast milk). Others, such as molluscum contagiosum, may spread through physical contact with an infected person's skin.
  • When a virus enters the body, the cells in the immune system start to attack the virus. This immune response causes nonspecific symptoms, including fever, chills, and a general feeling of discomfort.
  • Specific symptoms depend on the specific type and number of cells that become infected with the virus. For instance, HIV destroys the body's immune cells. As a result, patients are unable to fight against disease and infection effectively. Therefore, HIV patients are more likely to become sick.

Viral life cycle
  • General: Although it has been debated whether or not viruses are living organisms, most experts considered them non-living. This is because viruses do not meet all of the criteria to be classified as living organisms. For instance, viruses do not respond to stimuli, which is a common characteristic of living things.
  • The life cycle of a virus can be simplified and divided into five stages: attachment, penetration, uncoating, replication, and release. Uncoating only occurs in viruses that have outer shells.
  • Attachment: The virus attaches to specific proteins, called receptors, on the outer surface of human cells.
  • Penetration: Following attachment of the virus to membrane surface proteins, it enters the cell.
  • Uncoating: If the virus has an outer shell, it will go through a stage called uncoating. During this process, the virus releases its outer shell and expels its contents to prepare for replication.
  • Replication: Viral proteins and genetic material are assembled to make multiple copies while still inside the host cell.
  • Release: After many copies of the virus have been made, they are released from the host cell, often killing the host cell in the process. These newly formed viruses are now able to infect additional cells.

Common types of viral infections
  • Common cold: The common cold, also called acute viral nasopharyngitis, is a viral infection of the upper respiratory system, which may involve the nose, throat, sinuses, eustachian tubes (connects the ears to the throat), windpipe (trachea), voice box (larynx), and/or airways (bronchial tubes).
  • Common colds generally cause mild symptoms, such as runny nose and sore throat, which resolve on their own in about a week.
  • Patients can develop an infection after direct contact with the cold virus. This may happen when an individual touches environmental surfaces that have cold germs on them (e.g. public telephones, computer keyboards, or stair railings) and then touches the eyes, nose, or mouth. Colds may also be transmitted if a person inhales droplets of mucus that are contaminated with the cold virus. Mucus droplets may enter the air when an infected person coughs or sneezes. These droplets are invisible to the human eye and can remain in the air for several minutes.
  • Hepatitis A: Hepatitis A is a highly contagious liver infection that is caused by the hepatitis A virus (HAV). Although not usually as serious as other types of viral hepatitis, hepatitis A causes inflammation of the liver that may affect the liver's ability to function. The liver is primarily responsible for filtering most of the nutrients that are absorbed in the intestines, as well as removing drugs, alcohol, and toxins from the bloodstream.
  • Hepatitis A is transmitted when contaminated feces enter the mouth. This usually happens when a person consumes foods (especially produce that grows in the soil or food that is prepared by someone with dirty hands) or water that is contaminated.
  • Most cases of hepatitis A cause mild, if any, symptoms and do not require medical treatment. However, in rare cases, hepatitis A can be life threatening and cause liver failure.
  • Hepatitis B (HBV): The hepatitis B virus causes a serious liver infection. The infection can become chronic in some people and lead to liver failure, liver cancer, cirrhosis (permanent scarring and damage of the liver), or death.
  • The hepatitis B virus is transmitted through contact with bodily fluids such as the blood, semen, and vaginal discharge of someone who is infected. Even though HBV is transmitted by the same methods as HIV, hepatitis B is nearly 100 times more infectious. This is because HBV is more concentrated than HIV. Individuals of any age, race, nationality, gender, or sexual orientation can become infected with HBV.
  • There are few treatment options for patients with chronic hepatitis B, which is why people in the United States are required to receive the hepatitis B vaccination to prevent infection. In some cases, the doctor may suggest monitoring the patient's condition instead of treating it. In other instances, the doctor may recommend antiviral treatment or immunomodulatory therapy. When liver damage is severe, a liver transplantation may be the only treatment option.
  • Human immunodeficiency virus (HIV): The human immunodeficiency virus (HIV) is a virus that causes AIDS (acquired immune deficiency syndrome). HIV destroys important immune cells that are needed to fight off disease and infection. As a result, HIV patients are more likely to become sick.
  • HIV is transmitted from person to person via bodily fluids, including blood, semen, vaginal secretions, and breast milk. Therefore, it can be transmitted through sexual contact with an infected person, sharing needles/syringes with someone who is infected, breastfeeding, vaginal birth or, less commonly (and rare in countries where blood is screened for HIV antibodies), through transfusions with infected blood.
  • HIV is a fatal condition. Although antiretrovirals can help suppress the virus, they do not completely eliminate it from the blood. Once patients develop AIDS, they have an increased risk of developing fatal infections, such as pneumonia.
  • Influenza (flu): Influenza, commonly referred to as the flu, is a contagious viral infection of the respiratory system.
  • In general, the flu is more debilitating than the common cold and symptoms, such as fever, body ache, extreme fatigue, and dry cough, are more common and severe in patients with the flu. Infants, the elderly, and chronically ill patients have the greatest risk of developing severe cases of the flu that may be life threatening.
  • The flu is caused by a slightly different type of virus than the common cold. Patients can develop an infection after direct contact with the flu virus. This may happen when an individual touches environmental surfaces that have cold germs on them (e.g. public telephones, computer keyboards, or stair railings) and then touches the eyes, nose, or mouth.
  • Mononucleosis (mono): Mononucleosis, also called mono or the kissing disease, is a viral infection of white blood cells called monocytes.
  • Mono is caused by the Epstein-Barr virus. Although the virus is less contagious than the common cold, it may still be passed on to others. It is transmitted through saliva and airborne mucus droplets. Individuals can acquire the disease after kissing an infected person, sharing food utensils, or inhaling mucus droplets.
  • The infection resolves on its own. Patients do not receive antivirals because these medications may actually worsen the condition. Patients may receive treatment to help reduce symptoms. Most symptoms begin to improve after a few weeks. However, fatigue and an enlarged spleen and lymph nodes may take a few weeks longer to improve.
  • Measles, mumps, and rubella: Measles, mumps, and rubella are highly contagious viral infections. However, they are rare in countries, such as the United States, where individuals have access to vaccinations.
  • Measles is a viral infection of the respiratory tract. Mumps is a viral infection of the salivary glands that causes swelling. Rubella, also called German measles, is a mild infection of the respiratory tract that often goes unnoticed. However, if a pregnant woman develops rubella, it may lead to birth defects in the infant.
  • These infections are transmitted through airborne droplets. People become infected with the viruses when they inhale particles of infected sputum from the air. The viruses become airborne when an infected person expels saliva when they cough, sneeze, talk, spit, etc.
  • Molluscum contagiosum: Molluscum contagiosum is a viral infection of the skin that primarily affects children.
  • In children, small bumps are most likely to develop on the neck, arms, and face. In adults, small bumps usually develop on the genitals, upper thighs, and lower abdomen. When the genital region is affected in adults, it is considered a sexually transmitted disease (STD).
  • Molluscum contagiosum can spread through direct contact with infected skin. Individuals can also develop the infection after touching objects (e.g. towels, doorknobs, bed linens, or clothing) that came into contact with an infected person's skin.
  • Patients should not scratch or rub affected areas of the skin because it may cause the virus to spread to others areas. Heat and moisture may cause the virus to multiply faster.
  • Molluscum contagiosum does not cause any serious health problems. If left untreated, molluscum contagiosum will resolve on its own within one year. However, because the infection is highly contagious, treatment is recommended.

Copyright © 2011 Natural Standard (www.naturalstandard.com)


The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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