Paper Influenza

8/19/2019 Paper Influenza

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Swine Influenza

Definition

Shekhar R, Sharma P, Tyagi LK, et al. Swine flu (swine influenza-A (H11! "irus!# a re"iew.

$l%&al ' Pharma%.)**+(!#11-1).

Swine flu (swine influenza) is a respiratory disease caused by viruses (influenza viruses) that

infect the respiratory tract of pigs and result in nasal secretions, a barking-like cough,

decreased appetite, and listless behavior. Swine influenza viruses are most commonly of the

H! subtype, but other subtypes are also circulating in pigs (e.g., H!", H#!, H#!").

$igs can also be infected with avian influenza viruses and human seasonal influenza viruses

as well as swine influenza viruses. %he H#!" swine virus was thought to have beenoriginally introduced into pigs by humans. Sometimes pigs can be infected with more than

one virus type at a time, which can allow the genes from these viruses to mi&. %his can result

in an influenza virus containing genes from a number of sources, called a 'reassortant' virus.

lthough swine influenza viruses are normally species specific and only infect pigs, they do

sometimes cross the species barrier to cause disease in humans.

Epidemiology

Tau&en&erger 'K, %rens /. 1+10 nfluenza# the m%ther %f all 2an3emis. merg *nfect

+is. 'an )**41)(1!#15-)).

Swine influenza A (H11! infeti%n in tw% hil3ren--S%uthern 6alif%rnia, arh-A2ril

)**+. orb ortal kly ep. A2r )7 )**+50(15!#7**-)

Human cases of swine influenza (H!) have been reported worldwide. *n "//0, cases of

influenza like illness were first reported in e&ico on arch 12 the outbreak was

subse3uently confirmed as swine influenza . *nvestigation is continuing to clarify the spread

and severity of swine influenza in e&ico. Suspected clinical cases have been reported in 0

of the country4s #" states. lthough only 05 of the e&ican cases have been laboratory-

confirmed as Swine *nfluenza 6H! (" of them genetically identical to Swine *nfluenza

6H! viruses from 7alifornia ) appro&imately ,8// cases and over 9/ deaths have been

attributed to swine influenza in e&ico.

ccording to the H:, as of pril #/, "//0, swine flu has been laboratory-confirmed in countries; the <nited States, e&ico, ustria ( case), 7anada (0 cases), =ermany (# cases),



*srael (" cases), the !etherlands ( case), !ew >ealand (# cases), Spain (# cases),

Switzerland ( case), and the <nited ?ingdom (1 cases). :n pril "8, "//0, the <S

+epartment of Health and Human Services declared a national public health emergency

involving swine influenza , citing its significant potential to affect national security. *n the

<nited States, 0 confirmed cases of swine flu have been reported as of pril #/, "//0, in

rizona ( case), 7alifornia (@ cases), *ndiana ( case), ?ansas (" cases), assachusetts ("

cases), ichigan (" cases), !evada ( case), !ew Aork (9 cases), :hio ( case), and %e&as

(8 cases). ll affected patients have had mild influenzalike illness, with only two re3uiring

brief hospitalization. s of pril #/, "//0, only one death attributed to swine flu has been

reported in the <nited States, involving a "#-month-old child.

Shekhar R, Sharma P, Tyagi LK, et al. Swine flu (swine influenza-A (H11! "irus!# a re"iew.

$l%&al ' Pharma%.)**+(!#11-1).

Classification

%he three generation of influenza viruses that cause human flu, two also cause influenza in

pigs, with influenza- being common in pigs and influenza-7 being rare, *nfluenza-B has

not been reported in pigs. ithin influenza- and influenza-7, the strains found in pigs and

humans are largely distinct, although due to reassortment there have been transfers of genes

among strains crossing swine, avian and human species boundaries.

*nfluenza-;

Swine influenza is known to be caused by influenza- subtypes H ! , H!", H"!#, H#!

and H#!". *n pigs, three influenza- virus subtypes (H! , H!" and H#!" ) are the

most common strains worldwide. *n the <nited States, the H! subtype was e&clusively

prevalent among swine populations before 0012 however, since late ugust 001, H#!"

subtypes have been isolated from pigs. s of "//@, H#!" virus isolates in <S swine and

turkey stocks were triple reassortants, containing genes from human (H, ! and $B),

swine (!S, !$ and ) and avian ($B"and $)

*nfluenza-7;



*nfluenza-7 viruses infect both humans and pigs, but do not infect birds . %ransmissions

between pigs and humans have occurred in the past . Cor e&ample, influenza-7 caused small

outbreaks of a mild form of influenza amongst children in Dapan and 7alifornia, due to its

limited host range and the lack of genetic diversity in influenza-7, this form of influenza does

no cause pandemics in humans.

Transmission

*nfluenza virus is present in respiratory secretions of infected persons. s a result, influenza

virus can be transmitted through sneezing and coughing via large-particle droplets.

%ransmission via contact with surfaces that have been contaminated with respiratory droplets

or by aerosolized small-particle droplets may also occur, although these modes of

transmission have not been proven. *n addition to respiratory secretions, certain other

body fluids (e.g. diarrheal stool) should also be considered potentially infectious.

Pathophysiology

Swine flu is caused by a virus which targets the body4s respiratory cells and damages the

lining of the respiratory tract, leading to swelling and inflammation of the tract. H!

viruses are surrounded by a protein coat and a lipid envelop. *n the lipid layer, two surface

glycoproteins are embedded, they are hemagglutinin and neuraminidase. %he presumed

pathophysiology indicates that H! viruses are ! viruses that bind through hemagglutin

on to sialic acid sugars containing receptors on the surfaces of epithelial cells, which typically

affect the nose, throat and lungs of humans. %he virus is shed in respiratory secretions for 9-

/ days2 the virus attaches to and penetrates respiratory epithelial cells in the trachea and

bronchi, following respiratory transmission. Crom lungs it enters in the blood through alveoli

cells surrounded by a capillary network. *t acts on B-lymphocytes and B-cells are responsible

for the natural immunity.

Clinical Manifestation

%he clinical signs of Swine *nfluenza are typical flu-like symptoms. %he pigs will develop a

fever, (@/.9o7- @.5o7), nasal and ocular discharge, and severe spasms of coughing. %hey will

appear lethargic and become anorectic. %hese signs will appear very suddenly, spread rapidly

throughout the entire barn, and persist for about 5 days. %hen the pigs will almost recover

about as 3uickly as they develop clinical signs. %hese outbreaks typically occur in the fall andearly winter, and are more fre3uently seen in nursery through finishing age pigs.



*n Human patients, the symptoms similar to typical influenza like high fever, cough, and sore

throat, with some patients e&periencing diarrhea and vomiting. %he cases can rapidly progress

to severe and unusual pneumonia.

Diagnosis

+iagnosis of Swine *nfluenza can be based on clinical signs, virus isolation, histopathological

confirmation of lesions, paired serology, and antigen detection.

Management

6/6. Swine nfluenza (8lu!. 6enters f%r /isease 6%ntr%l an3 Pre"enti%n. A"aila&le at

htt2#99www.3.g%"9h1n1flu9 . Aesse3 /esem&er 1, )*1).

/%m:nguez-6herit $, La2insky S;, aias A;, Pint% R, ;s2in%sa-Perez L, 3e la T%rre A, et

al. 6ritially ll 2atients with )**+ influenza A(H11! in e<i%. D. %" 7

)**+*)(1=!#100*-=.>e3line?.

%reatment is largely supportive and consists of bedrest, increased fluid consumption, cough

suppressants, and antipyretics and analgesics (eg, acetaminophen, nonsteroidal anti-

inflammatory drugs) for fever and myalgias. Severe cases may re3uire intravenous hydration

and other supportive measures. ntiviral agents may also be considered for treatment or

prophyla&is. $atients should be encouraged to stay home if they become ill, to avoid close

contact with people who are sick, to wash their hands often, and to avoid touching their eyes,

nose, and mouth. %he 7+7 recommends the following actions when human infection with

swine flu is confirmed in a community.

Eaboratory testing has found the swine influenza (H!) virus susceptible to the

prescription antiviral drugs oseltamivir and zanamivir, and the 7+7 has issued interim

guidance for the use of these drugs to treat and prevent infection with swine influenza

viruses. s part of its preparation for the emergency, the <S +epartment of Homeland

Security is releasing "9F of stockpiled antiviral agents (ie, oseltamivir G%amiflu, zanamivir

Gelenza).

%he usual vaccine for influenza administered at the beginning of the flu season is not

effective for this viral strain. lso, other antiviral agents (eg, amantadine, rimantadine) are

http://www.cdc.gov/h1n1flu/

http://reference.medscape.com/medline/abstract/19822626

http://reference.medscape.com/medline/abstract/19822626

http://www.cdc.gov/h1n1flu/



not recommended because of recent resistance to other influenza strains documented over the

past several years.

Basic supportive care (ie, hydration, analgesics, cough suppressants) should be prescribed.

mpiric antiviral treatment should be considered for confirmed, probable, or suspected cases

of swine influenza. %reatment of hospitalized patients and patients at higher risk for influenza

complications should be prioritized.

*nitiation of antiviral agents within @1 hours of symptom onset is imperative for providing

treatment efficacy against influenza virus. *n studies of seasonal influenza, evidence for

benefits of treatment is strongest when treatment is started within @1 hours of illness onset.

However, some studies of treatment of seasonal influenza have indicated benefit, including

reductions in mortality or duration of hospitalization, even in patients in whom treatment was

started more than @1 hours after illness onset. %he recommended duration of treatment is 9

days.

• $rophyla&is with antiviral agents should also be considered in the following

individuals (pre-e&posure or poste&posure);

o 7lose household contacts of a confirmed or suspected case who are at high

risk for complications (eg, chronic medical conditions, persons I89 y or J9 y,

pregnant women)

o School children at high risk for complications who have been in close contact

with a confirmed or suspected case

o %ravelers to e&ico who are at high risk for complications (eg, chronic

medical conditions, persons I89 y or J9 y, pregnant women)

o Health care providers or public health workers who were not using appropriate

personal protective e3uipment during close contact with a confirmed or

suspected case

• $re-e&posure prophyla&is can be considered in the following persons;



o ny health care provider who is at high risk for complications (eg, persons

with chronic medical conditions, adults I89 y, pregnant women)

o *ndividuals not considered to be at high risk but who are nonetheless traveling

to e&ico, first responders, or border workers who are working in areas with

confirmed cases

Antiviral Agents

+rugs indicated for treatment of swine influenza (H!) virus include neuraminidase

inhibitors (ie, oseltamivir and zanamivir).

seltamivir !Tamiflu"

:seltamivir inhibits neuraminidase, which is a glycoprotein on the surface of influenza virus

that destroys an infected cell4s receptor for viral hemagglutinin. By inhibiting viral

neuraminidase, this agent decreases the release of viruses from infected cells and, thus, viral

spread. :seltamivir is effective in the treatment of influenza or B and must be administered

within @1 hours of symptom onset. %he sooner the drug is administered after symptom onset,

the better the likelihood of a good outcome. :seltamivir reduces the length of illness by an

average of .9 days. (*n a subgroup of high-risk patients, illness was reduced by ".9 d.) *n

addition, the severity of symptoms is also reduced.

:seltamivir is available as #/-mg, @9-mg, and 59-mg oral capsules and as a powder for

suspension that contains " mg6mE after reconstitution.

• dult dose

o %reatment for acute illness; 59 mg $: bid for 9 d

o $rophyla&is; 59 mg $: 3d

• $ediatric dose

o %reatment for acute illness and age J year

J# months; " mg $: bid



#-9 months; "/ mg $: bid

8- months; "9 mg $: bid

o %reatment for acute illness and age I year

J9 kg; #/ mg $: bid

9-"# kg; @9 mg $: bid

"#-@/ kg; 8/ mg $: bid

I@/ kg; dminister as in adults

o $rophyla&is and age J year

J# months; +ata limited2 not recommended unless situation Kudged

critical

#-9 months; "/ mg $: 3d

8- months; "9 mg $: 3d

o $rophyla&is and age I year

J9 kg; #/ mg $: 3d

9-"# kg; @9 mg $: 3d

"#-@/ kg; 8/ mg $: 3d

I@/ kg; dminister as in adults

#anamivir !$elenza"

>anamivir inhibits neuraminidase, which is a glycoprotein on the surface of the influenza

virus that destroys the infected cell4s receptor for viral hemagglutinin. By inhibiting viral

neuraminidase, release of viruses from infected cells and viral spread are decreased.



>anamivir is effective against both influenza and B. %he preparation of zanamivir is in

powder form for inhalation via the +iskhaler oral inhalation device. 7ircular foil discs that

contain 9-mg blisters of drug are inserted into the supplied inhalation device. *ndividuals with

asthma or other respiratory conditions that may decrease ability to inhale drug should be

given oseltamivir.

• dult dose

o %reatment for acute illness; / mg inhaled orally bid for 9 d

o $rophyla&is of household contact; / mg inhaled orally 3d for / d (initiate

within #8 h)

o $rophyla&is for community outbreak; / mg inhaled orally 3d for "1 d (initiate

within 9 d of outbreak)

• $ediatric dose

o %reatment for acute illness

J5 years; !ot established

I5 years; dminister as in adults

o $rophyla&is in household contact

J9 years; !ot established

I9 years; dminister as in adults

o $rophyla&is in community outbreak

dolescents "-8 years; dminister as in adults

Additional pediatric considerations



spirin or aspirin-containing products (eg, bismuth subsalicylate G$epto Bismol) should not

be included in the treatment of confirmed or suspected viral infection in persons aged 1

years or younger because of the risk of eye syndrome. Cor relief of fever, other antipyretic

medications (eg, acetaminophen, nonsteroidal anti-inflammatory drugs) are recommended.

Pregnant women

:seltamivir and zanamivir are '$regnancy 7ategory 7' medications, indicating that no

clinical studies have been conducted to assess the safety of these medications in pregnant

women. Because of the unknown effects of influenza antiviral drugs on pregnant women and

their fetuses, oseltamivir or zanamivir should be used during pregnancy only if the potential

benefit Kustifies the potential risk to the embryo or fetus2 the manufacturers4 package inserts

should be consulted. However, no adverse effects have been reported among women who

received oseltamivir or zanamivir during pregnancy or among infants born to women who

have received oseltamivir or zanamivir. $regnancy should not be considered a

contraindication to oseltamivir or zanamivir use. Because zanamivir is an inhaled medication

and has less systemic absorption, some e&perts prefer zanamivir over oseltamivir for use in

pregnant women, when feasible

Prevention

Prevention Components in Swine

ecently in this decade it has become a greater problem as evolution of the virus has resulted

in inconsistent responses to traditional vaccines. Standard commercial swine flu vaccines are

effective in controlling the infection when the virus strains match enough to have significant

cross protection. utogenous vaccines made from specific viruses isolated are created and

used in more difficult cases.

Prevention of Transmission in %umans

ecommendation is to use standard infection control against influenza. %his includes fre3uent

washing of hands with soap and water or with alcohol based hand sanitizers, especially being

out in public as influenza spreads in cough L sneezes, it is evident that little particles of

viruses can linger or table tops, telephones L other surfaces can be transmitted by fingers to

mouth, nose L eyes. lcohol based gel or foam destroy the viruses L bacteria.

Paper Influenza

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