Swine influenza Health Dictionary

Swine Influenza: From 1 Different Sources


a disease of domesticated pigs, first seen in humans in early 2009, caused by H1N1, a strain of *influenza A virus. Very contagious, the World Health Organization has now declared it to be a pandemic strain in humans. Swine influenza is currently believed not to be as virulent as *avian influenza and it seems to be less severe than the virulent 1918 pandemic, with which it shares antigenic features.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Influenza

A specific type of acute viral respiratory infection, with one virus (many strains) and a short, nasty stay. A few thousand people die from it every year, but humans alive at present have almost universal partial resistance. It was not so during WWI, when it first began to spread. It was variously called Spanish Influenza, La Grippe, and Influenza (Italian for Influence)...everyone blamed some other country for it. The Turks and Armenians took a break from mutual mutilation and blamed it on each other, since it was killing as many people as the 1,000,000 fatalities THAT bit of genocide fostered. It ran across the world like some Bergmanesque horseman, and killed at least 20 million people before it petered out around 1925. The villages of Northern New Mexico, filled with grim and genetically toughened Spanish settlers, survivors of terrible weather, 300 years of isolation, the Inquisition and Anglo carpetbaggers, suffered fatalities that reached 40% in some places. The flu is new.... influenza

Chinese Avian Influenza

A variety of in?uenza in chickens occurring in southern China that in 1997 appeared to jump the species barrier and infect humans. Some cases of the human version of the infection occurred in Hong Kong. There were fears of a serious epidemic which, because of a lack of natural resistance among humans, might have led to its worldwide spread. This has not so far occurred.... chinese avian influenza

Influenza

In?uenza is an acute infectious disease, characterised by a sudden onset, fever and generalised aches and pains. It usually occurs in epidemics and pandemics (see EPIDEMIC; PANDEMIC).

Cause The disease is caused by a VIRUS of the in?uenza group. There are at least three types of in?uenza virus, known respectively as A, B and

C. One of their most characteristic features is that infection with one type provides no protection against another. Equally important is the ease with which the in?uenza virus can change its character. It is these two characteristics which explain why one attack of in?uenza provides little, if any, protection against a subsequent attack, and why it is so di?cult to prepare an e?ective vaccine against the disease.

Epidemics of in?uenza due to virus A occur in Britain at two- to four-year intervals, and outbreaks of virus B in?uenza in less frequent cycles. Virus A in?uenza, for instance, was the prevalent infection in 1949, 1951, 1955 and 1956, whilst virus B in?uenza was epidemic in 1946, 1950, 1954 and, along with virus A, in 1958–59. The pandemic of 1957, which swept most of the world, although fortunately not in a severe form, was due to a new variant of virus A

– the so-called Asian virus – and it has been suggested that it was this variant that was responsible for the pandemics of 1889 and 1918. Since 1957, variants of virus A have been the predominating causes of in?uenza, accompanied on occasions by virus B.

In 1997 and 2004, outbreaks of Chinese avian in?uenza caused alarm. The in?uenza virus had apparently jumped species from birds

– probably chickens – to infect some people. Because no vaccine is available, there was a risk that this might start an epidemic.

Symptoms The incubation period of in?uenza A and B is 2–3 three days, and the disease is characterised by a sudden onset. In most cases this is followed by a short, sharp febrile illness of 2–4 days’ duration, associated with headache, prostration, generalised aching, and respiratory symptoms. In many cases the respiratory symptoms are restricted to the upper respiratory tract, and consist of signs of irritation of the nose, pharynx and larynx. There may be nosebleeds, and a dry, hacking cough is often a prominent and troublesome symptom. The fever is usually remittent and the temperature seldom exceeds 39·4 °C (103 °F), tending to ?uctuate between 38·3 and 39·4 °C (101 and 103 °F).

The most serious complication is infection of the lungs. This infection is usually due to organisms other than the in?uenza virus, and is a complication which can have serious results in elderly people.

The very severe form of ’?u which tends to occur during pandemics – and which was so common during the 1918–19 pandemic – is characterised by the rapid onset of bronchopneumonia and severe prostration. Because of the toxic e?ect on the heart, there is a particularly marked form of CYANOSIS, known as heliotrope cyanosis.

Convalescence following in?uenza tends to be prolonged. Even after an attack of average severity there tends to be a period of weakness and depression.

Treatment Expert opinion is still divided as to the real value of in?uenza vaccine in preventing the disease. Part of the trouble is that there is little value in giving any vaccine until it is known which particular virus is causing the infection. As this varies from winter to winter, and as the protection given by vaccine does not exceed one year, it is obviously not worthwhile attempting to vaccinate the whole community. The general rule therefore is that, unless there is any evidence that a particularly virulent type of virus is responsible, only the most vulnerable should be immunised – such as children in boarding schools, elderly people, and people who suffer from chronic bronchitis or asthma, chronic heart disease, renal failure, diabetes mellitus or immunosuppression (see under separate entries). In the face of an epidemic, people in key positions, such as doctors, nurses and those concerned with public safety, transport and other public utilities, should be vaccinated.

For an uncomplicated attack of in?uenza, treatment is symptomatic: that is, rest in bed, ANALGESICS to relieve the pain, sedatives, and a light diet. A linctus is useful to sooth a troublesome cough. The best analgesics are ASPIRIN or PARACETAMOL. None of the sulphonamides or the known antibiotics has any e?ect on the in?uenza virus; on the other hand, should the lungs become infected, antibiotics should be given immediately, because such an infection is usually due to other organisms. If possible, a sample of sputum should be examined to determine which organisms are responsible for the lung infection. The choice of antibiotic then depends upon which antibiotic the organism is most sensitive to.... influenza

Haemophilus Influenzae

A bacterium (see bacteria) responsible for numerous cases of the infectious diseases epiglottitis and meningitis.... haemophilus influenzae

Avian Influenza

a disease of poultry and other birds caused by strains of *influenza A virus. The severity of the disease depends on the strain of virus involved: H5N1 is particularly deadly (causing fowl plague (or pest), with a mortality approaching 100%) and very contagious, being spread between domestic flocks by wild birds. This virus is not easily transmissible to humans, requiring close contact with infected birds or their faeces. The first human cases of H5N1 infection (‘bird flu’) were reported in 1997 and restricted to Hong Kong: 18 people were infected, six of whom died. Since then half of the people infected with H5N1 in Asia, Europe, the Near East, and Africa have died. Most cases of avian influenza in humans have resulted from contact with infected poultry; human-to-human transmission has been extremely rare. However, if H5N1 should develop this ability, a serious pandemic could occur. See also swine influenza.... avian influenza



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