SWINE INFLUENZA -deeper view-










SWINE INFLUENZA


An acute contagious febrile disease of swine that is marked by severe coughing and inflammation of the upper respiratory tract, that sometimes develops into bronchopneumonia but is rarely fatal, that is caused by infection with a subtype (H1N1 or sometimes H3N2) of the orthomyxovirus causing influenza A, and that is often complicated by infection with another microorganism (as the pseudorabies virus or a pneumonia-causing bacterium)—called also swine flu


Normally, people do not contract Swine Influenza, which is a respiratory disease occurring regularly in pigs, and is caused by type A influenza viruses. However, according to The Center for Disease Control and Prevention, human Swine Influenza infections can and do happen. Most commonly, human cases of swine flu happen in people who are around pigs.While analyzing the data from the current outbreak, however, the Center for Disease Control and Prevention has determined that Swine Influenza is contagious and is spreading from human to human. While it is not known at this time how easily the virus spreads between people, the current indicators suggest Swine Influenza spreads the same way as seasonal flu - person-to-person through coughing or sneezing of infected people.If, at this point, you are thinking about giving up bacon, don't. Swine influenza viruses are not spread by food.
According to the Center for Disease Control and Prevention, "you cannot get swine influenza from eating pork or pork products. Eating properly handled and cooked pork products is safe."
All of the current United States cases of Swine Influenza reported by the Center for Disease Control and Prevention have occurred in San Diego County or Imperial County California or Guadalupe County, Texas. The Center for Disease Control and Prevention recommends that people living in the areas who become ill with influenza-like symptoms, including fever, body aches, runny nose, sore throat, nausea, or vomiting or diarrhea contact their health care provider to determine whether influenza testing or treatment is needed.




While in the United States there have been two fatal outbreaks of Swine Influenza, the last recorded death due to the illness occurred in 1988, when a Wisconsin woman was hospitalized for Pneumonia after being infected with Swine Influenza.Luckily today there are medicines which reduce the likelihood of Swine Influenza developing into anything more serious than a normal Flu. The Center for Disease Control and Prevention recommends using of oseltamivir or zanamivir for the treatment
Human Cases of Swine Influenza Investigated
Date: April 24, 2009
San Diego, CAUnited States of America
prevention of infection with these swine influenza viruses, which may also prevent serious complications from Swine Influenza.
However, theses work best if started soon after getting sick.Human Swine Influenza Investigation, www.cdc.govBird Flu in Egypt and Swine Flu in California Raise Guarded Concerns, discovermagazine.com






Influenza vaccine:v This vaccine protects people against the flu.


The flu is a contagious respiratory disease caused by an influenza virus. In the U.S., flu outbreaks typically occur in winter months. Symptoms include fever, chills, sore muscles, and cough. Thousands of people in the U.S. die each year from the flu or its complications. Most of those who die are the elderly, young children, or people with compromised immune systems.
See article on the flu for more information.
The viruses that typically cause the flu are primarily categorized as influenza type A or type B. Influenza type B does not change much over time, but type A can mutate rapidly. Therefore, a new form of the flu vaccine must be developed each year to protect people for the exact strain that is expected to be most prevalent.
All the influenza viruses in the flu shot are killed (inactive), so it is not possible to get the flu from this type of vaccine. However, some people do experience a low-grade fever for a day or two after the shot as their immune systems gear up to recognize the virus. (See "Risks" section in this article.)
A new nasal spray-type flu vaccine called FluMist is proving to be effective and safe in healthy people aged 2 to 49 years old. The FDA-approved vaccine helps the lining of the nose fight off actual viral infections. (FluMist uses a live, weakened virus instead of a dead one like the flu shot.) In one study, the nasal spray provided protection against the flu in up to 93% of children. It should not be used in those who have asthma or children under age 5 who have repeated wheezing episodes.
Flu vaccines are generally given at the beginning of the "flu season" -- usually late October or early November in the U.S. People traveling to other countries should be aware the flu may occur at different times.
IMMUNIZATION SCHEDULE
According to the U.S. Centers for Disease Control and Prevention, anyone who wants to reduce their risk of the flu can get a flu shot. The flu shot is approved for anyone older that 6 months of age. Some people have a higher risk of the disease. You should be vaccinated each year if you:
Are 50 or older
Have chronic lung or heart disease
Have sickle cell anemia and other hemoglobinopathies
Live in a nursing home or extended care facilities
Live in any type of housing where there are chronic health problems
Have kidney disease, anemia, severe asthma, diabetes, or chronic liver disease
Have a weakened immune system (including those with cancer or HIV/AIDS)
Receive long-term treatment with steroids for any condition
Expect to be past the 3rd month of pregnancy during the flu season (you may want to consider requesting the mercury-free flu vaccine)
Children and teenagers receiving long-term aspirin therapy and children between the age of 6 months and 2 years should also receive a flu shot each year. Mercury-free vaccines are preferred in younger children.
The flu shot is encouraged for:
Health care providers who work in high-risk settings
Direct contacts or caretakers of high-risk individuals
People who have in-home contact with children who are younger than 5 years old
People who provide essential community services
People living in dormitories or other crowded conditions
Anyone who wants to reduce their change of getting influenza
Children under age 9 require two shots 1 month apart the first time that they receive influenza vaccine. Older children and adults only require a single shot each year.
BENEFITS
Most people achieve protection from the flu approximately 2 weeks after receiving the vaccine.
Immunization of high-risk people reduces the risk of death from the flu. Immunization of those caring for high-risk people reduces the risk of spreading the disease to other people who may have a higher than average risk for complications.
RISKS
Most people have no side effects from the flu shot. Soreness at the injection site or minor aches and low grade fever may be present for several days.
Unlike the swine flu vaccine used in 1976, flu vaccines in recent years have shown no association with Guillain-Barre syndrome (GBS) in children, and an extremely small increase in the risk of GBS in adults. This risk is far outweighed by the number of severe flu cases prevented by immunization.
As is the case with any drug or vaccine, there is a rare possibility of allergic reaction.
WHO SHOULD NOT RECEIVE A FLU VACCINE
According to the CDC, some people should not be vaccinated without first talking to a doctor. In general, you should not get a flu shot if you:
Had a severe allergic reaction to chickens or egg protein
Have a fever or illness that is more than "just a cold"
Had a moderate to severe reaction after a previous flu vaccine
Are a woman who is, or might be, in the first trimester of pregnancy (first 3 months of pregnancy)
Have ever been paralyzed due to Guillain-Barre Syndrome
If you meet any of the above criteria, ask your doctor if a flu vaccine is safe for you.

Source: Daniel Rauch, M.D., FAAP., Director, Pediatric Hospitalist Program, New York University School of Medicine New York, NY. Review provided by VeriMed Healthcare Network
NYU Pediatric Inpatient Associates





MERCK & Co Inc LABORARTORY


Swine influenza is an acute, highly contagious, respiratory disease that results from infection with type A influenza virus. Field isolates of variable virulence exist, and clinical manifestation may be determined by secondary organisms. Pigs are the principal hosts of classic swine influenza virus. (Human infections have been reported, but porcine strains of influenza A do not appear to easily spread in the human population. However, deaths have occurred in immunocompromised people.) The disease in swine occurs commonly in the midwestern USA (and occasionally in other states), Mexico, Canada, South America, Europe (including the UK, Sweden, and Italy), Kenya, China, Japan, Taiwan, and other parts of eastern Asia.
Etiology:
Swine influenza virus (SIV) is an orthomyxovirus of the influenza A group with hemagglutinating antigen H1 and neuraminidase antigen N1 (ie, H1N1). Recently, new subtypes of SIV have been reported (H3N2, H1N2). Influenza B and C viruses have been isolated from pigs but have not caused the classic disease.
The classic type A infection with isolates of mild virulence may favor replication of pseudorabies virus ( Pseudorabies: Introduction), Haemophilus parasuis (see glässer’s disease, Glässer’s Disease: Introduction), Actinobacillus pleuropneumoniae ( Contagious Bovine Pleuropneumonia), and Mycoplasma hyopneumoniae ( Mycoplasmal Pneumonia), any of which may complicate outbreaks. The mixing of carrier and nonimmune pigs is an important predisposing factor.
The virus is unlikely to survive outside living cells for >2 wk except in cold conditions. It is readily inactivated by disinfectants.

Transmission and Epidemiology:
In North America, outbreaks are most common in fall or winter, often at the onset of particularly cold weather. In warmer areas of the world, infection may occur at any time. Usually, an outbreak is preceded by one or two individual cases and then spreads rapidly within a herd, mainly by aerosolization and pig-to-pig contact. The virus survives in carrier pigs for up to 3 mo and can be recovered from clinically normal animals between outbreaks. In antibody-positive herds, outbreaks of infection recur as immunity wanes. Up to 40% of herds may contain antibody-positive pigs. Carrier pigs are usually responsible for the introduction of SIV into previously uninfected herds and countries


Pathogenesis:
The spectrum of infection ranges from subclinical to acute. In the classic acute form, the virus multiplies in bronchial epithelium within 16 hr of infection and causes focal necrosis of the bronchial epithelium, focal atelectasis, and gross hyperemia of the lungs. Bronchial exudates and widespread atelectasis, seen grossly as plum-colored lesions affecting individual lobules of apical and intermediate lobes occur after 24 hr. The lesions continue to develop until 72 hr after infection, after which the virus becomes more difficult to demonstrate. Losses in reproduction associated with primary outbreaks appear to be secondary because virus has been recovered only rarely from the fetus.

Clinical Findings:
A classic acute outbreak is characterized by sudden onset and rapid spread through the entire herd, often within 1-3 days. The main signs are depression, fever (to 108°F [42°C]), anorexia, coughing, dyspnea, weakness, prostration, and a mucous discharge from the eyes and nose. Mortality is generally 1-4%. The overt course of the disease is usually 3-7 days in uncomplicated infections, with clinical recovery of the herd almost as sudden as the onset. However, virus may continue to cycle among pigs when clinical signs are suppressed by immune responses. Some pigs may become chronically affected. In herds that are in good condition, the principal economic loss is from stunting and delay in reaching market weight. Some increase in piglet mortality has been reported, and effects on herd fertility, including abortions in late pregnancy, may follow outbreaks in nonimmune herds. Lesions:
In uncomplicated infections, the lesions usually are confined to the chest cavity. The pneumonic areas are clearly demarcated, collapsed, and purplish red. They may be distributed throughout the lungs but tend to be more extensive and confluent ventrally. Nonpneumonic areas are pale and emphysematous. The airways contain a copious mucopurulent exudate, and the bronchial and mediastinal lymph nodes are edematous but rarely congested. There may be severe pulmonary edema, especially of interlobular septae, or a serous or serofibrinous pleuritis. Histologically, the lesions, when fully developed, are primarily those of an exudative bronchiolitis with some interstitial pneumonia.

Diagnosis:
A presumptive diagnosis can be made on clinical and pathologic findings, but confirmation depends on isolation of the virus or demonstration of virus-specific antibody. Virus can be isolated from nasal secretions in the febrile phase or from affected lung tissue in the early acute stage. A retrospective diagnosis can be made by demonstrating a rise in virus-specific antibodies in acute and convalescent serum samples, using the hemagglutination inhibition test. Both H3 and H1 subtype antigens should be included. This test is also used for herd surveys. To diagnose uncomplicated influenza infection, conditions such as pasteurellosis, pseudorabies, porcine reproductive and respiratory syndrome, and chlamydial and Haemophilus infections must be eliminated.

Treatment and Control:
There is no effective treatment, although antimicrobials may reduce secondary bacterial infections. Expectorants may help relieve signs in severely affected herds. Vaccination and strict import controls are the only specific preventive measures. Good management practices and freedom from stress, particularly due to crowding and dust, help reduce losses. Commercially available killed vaccines that contain both H1N2 and H3N2 subtypes appear to induce a strong protective immune response.


Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck discovers, develops, manufactures and markets vaccines and medicines to address unmet medical needs. The Company devotes extensive efforts to increase access to medicines through far-reaching programs that not only donate Merck medicines but help deliver them to the people who need them. Merck also publishes unbiased health information as a not-for-profit service.

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