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  SWINE FLU: AN OVERVIEW Priyanka Lokwani, Pramod Kumar, Yozana Upadhyay, Stuti Gupta, Renu Solanki and Nisha Singh AS!RA ! Swine flu (swine influenza) is a respiratory disease caused by viruses (influenza viruses belonging to family Orthomyxoviridae) that infect the respiratory tract of pigs and result in nasalsecretions, a barking-like cough, decreased appetite, and listless behaviour Oseltamivir (!amiflu)and zanamivir ( elenza) is the recommended drug both for prophylaxis and treatment !he besttreatment for influenza infections in humans is prevention by vaccination  Key words # Swine flu, respiratory tract infection, $%&% virus, influenza virus #N!R$%U !#$N 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 ('ouvier et al, *) + highly contagious form of influenza seen in swine,caused by a virus of the family Orthomyxoviridae (imura et al, %.) !he infection iscommunicable to humans and caused a worldwide epidemic in %%*!he $%&% virus (swine flu)is a new flu virus strain that has caused a worldwide pandemic in humans from /une  to+ugust %!he 0enters for 1isease 0ontrol and 2revention now call the virus  $%&%, anacute and highly contagious respiratory disease of swine caused by the orthomyxo virus thoughtto be the same virus that caused the %%* influenza pandemic an acute febrile highly contagiousviral disease + highly contagious form of human influenza caused by a filterable virus identicalor related to a virus formerly isolated from infected swine !he respiratory infection popularlyknown as swine flu is caused by an influenza virus first recognized in spring , near the endof the usual &orthern $emisphere flu season !he new virus,  $%&%, spreads 3uickly andeasily (4atsuzaki et al, ) + few months after the first cases were reported, rates of confirmed $%&%-related illness were increasing in almost all parts of the world +s a result, the5orld $ealth Organization declared the infection a global pandemic !hat official designationremained in place for more than a year !echnically, the term 6swine flu6 refers to influenza in pigs Occasionally, pigs transmit influenza viruses to people, mainly hog farm workers andveterinarians (7ynch et al, .) Symptoms o& Swine 'lu Swine flu produces most of the same symptoms in pigs as human flu produces in people( Yassine HM, 2007 ) Swine flu can last about one to two weeks in pigs that survive 8n a number of   instances, people have developed the swine flu infection whenthey are closely associated with pigs (for example, farmers, pork  processors), and likewise, pig populations have occasionally beeninfected with the human flu infection 8nvestigators think the swine flu strain, first seen in 4exico, should be termed novel$%&% flu since it is mainly found infecting people and exhibitstwo main surface antigens, $% (hemagglutinin type %) and &%(neuraminidase type%) ecent investigations show the eight &+strands from novel $%&% flu have one strand derived from humanflu strains, two from avian (bird) strains, and five from swinestrains ( $einen 2, 9)Shortness of breath or cough 7oss of appetite+ching muscles Swine 'lu Symptoms (s) a old or Sinus #n&e*tion + $aber 2 et   al,   8t is important to keep in mind most children with arunny nose or cough will not have swine flu and will not have tosee their pediatrician for swine flu testing 'ig -  shows 8nfluenza :irus (;ilchrist 4/, .) Symptoms of swine flu infections include (+ntonovics /, <)#=ever, which is usually high, but unlike seasonal flu, is sometimes absent0ough unny nose or stuffy nose Sore throat 'ody aches $eadache 0hills =atigue or tiredness, which can be extreme1iarrhoea and vomiting, sometimes, but more commonly seen than with seasonal fluSigns of a more serious swine flu infection might include pneumonia and respiratory failure Serious Swine 'lu Symptoms +S*hme*k , .arold /) -012 4ore serious symptoms that would indicate that a child with swine flu would need urgent medical attention include# =ast breathing or trouble breathing 'luish or gray skin color  &ot drinking enough fluids Severe or persistent vomiting &ot waking up or not interacting 'eing so irritable that the child does not want to be held =lu-like symptoms improve but then return with fever and worse cough>nusual tiredness$eadache unny nose Sore throat 'ig 3) shows symptoms of swine =lu (2atterson 1, %%) .igh4risk groups +5ellozzi ,36607 $igh isk group includes persons having0hronic (long-term) lung disease 0hronic heart disease 0hronic kidney disease 0hronic liver disease 0hronic neurological disease (neurological disorders include chronic fatigue syndrome, multiple sclerosis and parkinson?s disease)8mmunosuppression (whether caused by disease or treatment)1iabetes mellitus+lso at risk are#2atients who have had drug treatment for asthma within the past three years2regnant women2eople aged <@ and older (gaydos Ac,<) PA!.$P.YS#$L$GY $' S8#N9 'LU =irst, the influenza viruses (types +, ', 0) are enveloped &+ viruses with a segmented genomeB this means the viral &+genetic code is not a single strand of &+ but exists as eightdifferent &+ segments in the influenza viruses + human (or  bird) influenza virus can infect a pig respiratory cell at the sametime as a swine influenza virusB some of the replicating &+  strands from the human virus can get mistakenly enclosed inside theenveloped swine influenza virus =or example, one cell could containeight swine flu and eight human flu &+ segments !he total number of &+ types in one cell would be %<B four swine and four human flu &+ segments could be incorporated into one particle, making aviable eight &+ segmented flu virus from the %< available segmenttypes :arious combinations of &+ segments can result in a newsubtype of virus (known as antigenic shift) that may have the ability to preferentially infect humans but still show characteristics uni3ue tothe swine influenza virus (=igure 9) 8t is even possible to include &+ strands from birds, swine, and human influenza viruses into onevirus if a cell becomes infected with all three types of influenza (for example, two bird flu, three swine flu, and three human flu &+segments to produce a viable eight-segment new type of flu viralgenome) =ormation of a new viral type is considered to be antigenicshiftB small changes in an individual &+ segment in flu viruses aretermed antigenic drift and result in minor changes in the virus$owever, these can accumulate over time to produce enough minor changes that cumulatively change the virus antigenic makeup over time (usually years)Second, pigs can play a uni3ue role as anintermediary host to new flu types because pig respiratory cells can beinfected directly with bird, human, and other mammalian flu viruses0onse3uently, pig respiratory cells are able to be infected with manytypes of flu and can function as a 6mixing pot6 for flu &+ segments(=igure 9) 'ird flu viruses, which usually infect the gastrointestinalcells of many bird species, are shed in bird faeces 2igs can pick theseviruses up from the environment and seem to be the maAor way that bird flu virus &+ segments enter the mammalian flu virus population (4cinney 52 et al, %) 'ig :  Shows 2athophysiology of Swine =lu ($einen, 2 (9) %#AGN$S#S + ;ray ;0,   + 3uick test (for example, nasopharyngeal swab sample) is doneto see if the patient is infected with influenza + or ' virus 4ostof the tests can distinguish between + and ' types !he test can be negative (no flu infection) or positive for type ', the flu is notlikely to be swine flu ($%&%) 8f it is positive for type +, the person could have a conventional flu strain or swine flu ($%&%)$owever, the accuracy of these tests has  been challenged, and the >S 0enters =or 1isease 0ontroland 2reventation (010) has not completed their comparativestudies of these tests, however, a new test developed by the010 and a commercial company reportedly can detect $%&%reiably in about one hourB as of October , the test is onlyavailable to the militarySwine flu ($%&%) is definitively diagnosed by identifying the  particular antigens associated with the virus type 8n general, this test done in a specialized laboratory and is not done by many doctorCs offices or hospital laboratories $owever, doctorCs offices are able to send specimens to specialize laboratories if necessary 'ecause of the larger number of novel $%&% swine flu cases (as of October , the vast maAority of flu cases (about D) are due to novel $%&% flu :iruses), the 010 recommends only hospitalizes patientCs flu virus strains be sent to reference labs to be identified !reatment + 4yers 2, <  !he guiding principles are#Early implementation of infection control precautions to minimize+nosocomical F household spread of disease'2rompt treatment to prevent severe illness G death0Early identification and follow up of persons at risk -)$seltami(ir /edi*ation Oseltamivir is the recommended drug both for prophylaxis and treatment1ose for treatment is as follows#'y 5eight# ‐ =or weight H%@kg 9 mg '1 for @ days ‐ %@-9kg I@ mg '1 for @ days ‐ I-HIkg < mg '1 for @ days ‐ JIkg .@ mg '1 for @ days 9 K =or infants# ‐ H 9 months % mg '1 for @ days ‐ 9-@ months  mg '1for@days ‐ <-%% months @ mg '1 for @ days ‐ 8t is also availableas syrup (%mg perml) ‐ 8f needed dose G duration can be modified as per clinical condition( ichard E,%.*) Ad(erse rea*tions Oseltamivir is generally well tolerated, gastrointestinal side effects(transient nausea, vomiting) may increase with increasing doses, particularly above 9 mgFday Occasionally it may cause bronchitis, insomnia and vertigo 7ess commonly angina, pseudomembranous colitis and peritonsillar abscess have also beenreported !here have been rare reports of anaphylaxis and skinrashes 8n children, most fre3uently reported side effect isvomiting 8nfre3uently, abdominal pain, epistaxis, bronchitis, otitismedia, dermatitis and conAunctivitis have also been observed  3)Supporti(e therapy  8: =luids  2arentral nutrition  Oxygen therapyF ventilatory support  +ntibiotics for secondary infection  :asopressors for shock  2aracetamol or ibuprofen is prescribed for fever, myalgiaand headache 2atient is advised to drink plenty of fluidsSmokers should avoid smoking =or sore throat, shortcourse of topical decongestants, saline nasal drops, throatlozenges and steam inhalation may be beneficial  Salicylate F aspirin is strictly contraindicated in anyinfluenza patient due to its potential to cause eyeCssyndrome  !he suspected cases would be constantly monitored for clinical Fradiological evidence of lower respiratory tractinfection and for hypoxia (respiratory rate, oxygensaturation, level of consciousness)  2atients with signs of tachypnea, dyspnea, respiratorydistress and oxygen saturation less than  per cent should be supplemented with oxygen therapy !ypes of oxygendevices depend on the severity of hypoxic conditions whichcan be started from oxygen cannula, simple mask, partialre-breathing mask (mask with reservoir bag) and nonrebreathing mask 8n children, oxygen hood or head boxescan be used  2atients with severe pneumonia and acute respiratory failure(SpO H D and 2aO H< mm$g with oxygen therapy)must be supported with mechanical ventilation 8nvasivemechanical ventilation is preferred choice &on invasiveventilation is an option when mechanical ventilation is notavailable !o reduce spread of infectious aerosols, use of $E2+ filters on expiratory ports of the ventilator circuit Fhigh flow oxygen masks is recommended  4aintain airway, breathing and circulation (+'0)B  4aintain hydration, electrolyte balance and nutrition  8f the laboratory reports are negative, the patient would bedischarged after giving full course of oseltamivir Even if the test results are negative, all cases with strongepidemiological criteria need to be followed up  8mmunomodulating drugs has not been found to be beneficial in treatment of + 1S or sepsis associated multiorgan failure $igh dose corticosteroids in particular haveno evidence of benefit and there is potential for harm 7owdose corticosteroids ($ydrocortisone -I mgF day)may be useful in persisting septic shock (S'2 H )  Suspected case not having pneumonia do not re3uireantibiotic therapy +ntibacterial agents should beadministered, if re3uired, as per locally accepted clinical practice guidelines 2atient on mechanical ventilationshould be administered antibiotic prophylactically to prevent hospital associated infections :)%is*harge Poli*y  +dult patients should be discharged . days after symptomshave subsided  0hildren should be discharged %I days after symptoms have subsided  !he family of patients discharged earlier should beeducated on personal hygiene and infection controlmeasures at homeB children should not attend schoolduring this period ;) hemo Prophyla<is  +ll close contacts of suspected, probable and confirmedcases 0lose contacts include household Fsocial contacts,family members, workplace or school contacts, fellowtravelers etc  +ll health care personnel coming in contact with suspected,  probable or confirmed cases  Oseltamivir is the drug of choice  2rophylaxis should be provided till % days after last exposure (maximum period of < weeks)  'y 5eight# ‐ =or weight H%@kg 9 mg O1 ‐ %@-9kg I@ mg O1 ‐ I-HIkg < mg O1 ‐ JIkg .@ mg O1  =or infants# ‐ H 9 months not recommended unless situation Audged critical due to limited data on use in this age group ‐ 9-@ months  mg O1 ‐ <-%% months @ mg O1 =)Non4Pharma*euti*al #nter(entions + 7indstrom SE,I  0lose 0ontacts of suspected, probable and confirmed casesshould be advised to remain at home (voluntary home 3uarantine) for at least . days after the last contact with the case 4onitoring of fever should be done for at least . days 2rompt testing and hospitalizationmust be done when symptoms are reported +ll suspected cases,clusters of 878FS+ 8 cases need to be notified to the State $ealth+uthorities and the 4inistry of $ealth & =amily 5elfare, ;ovt of 8ndia (1irector, E4 and &801) 8f a person becomes sick with swine flu, antiviral drugs can make theillness milder and make the patient feel better faster !hey mayalso prevent serious flu complications =or treatment, antiviraldrugs work best if started soon after getting sick (within  days of symptoms) 'eside antivirals, supportive care at home or inhospital, focuses on controlling fevers, relieving pain andmaintaining fluid balance, as well as identifying and treating anysecondary infections or other medical problems !he >S 0entersfor 1isease 0ontrol and 2revention recommends the use of !amiflu (oseltamivir) or elenza (zanamivir) for the treatmentandFor prevention of infection with swine influenza virusesB
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