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Biological Health Hazard – Swine influenza, sub-type H3N2V (human infection): Michigan and Ohio

2016/08/18

INFLUENZA, SWINE (04): USA (MICHIGAN, OHIO), HUMAN CASES H3N2V
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Published Date: 2016-08-17 15:34:54
Subject: PRO/AH/EDR> Influenza, swine (04): USA (MI, OH), human cases H3N2V
Archive Number: 20160817.4420280

Date: 13 Aug 2016
Source: Outbreak News Today [edited]

Four human infections with influenza viruses that normally circulate in swine (swine influenza) were reported by CDC this week. When swine influenza viruses are detected in people, they are called “variant” viruses and are designated with a letter v at the end of the virus subtype. The 4 human infections were caused by H3N2v viruses in Ohio (2) and Michigan (2). All 4 patients reported attending fairs where they had exposure to pigs during the week preceding illness onset. Pigs at the fairs have reportedly tested positive for swine influenza A (H3N2) infection. The Ohio patients are not related other than that both of them reported having attended the same fair in Ohio. Similarly, the Michigan cases both attended the same fair in Michigan but are otherwise unrelated to each other.

CDC is working with state public health officials to support their human health responses and has recommendations for the public on what steps they can take to help protect against H3N2v and other swine influenza viruses.

Swine influenza is a respiratory disease of pigs caused by type A influenza viruses that cause outbreaks in pigs. Signs of swine flu in pigs can include fever, coughing (barking), sneezing, breathing difficulties, eye redness or inflammation, and not eating. Some pigs infected with influenza, however, may show no signs of illness at all.

Swine flu viruses do not normally infect people; however, sporadic human infections with these viruses have occurred. Human infections with H1N1v, H3N2v and H1N2v viruses have been detected in the United States. Spread between pigs and people is thought to happen mainly when an infected pig (or human) coughs or sneezes and droplets with influenza virus in them spread through the air. If these droplets land in the nose or mouth, or are inhaled, that person (or pig) could be infected. There also is some evidence that the virus might spread by touching something that has virus on it and then touching the mouth or nose. A 3rd way to possibly get infected is to inhale particles containing influenza virus. Influenza has not been shown to be transmissible to people through eating properly handled and prepared pork (pig meat) or other products derived from pigs.

Most commonly, human infections with variant viruses occur in people with exposure to infected pigs (e.g., at a fair or at work). Illness associated with variant virus infection includes symptoms similar to those of seasonal flu. Most illness has been mild, but as with seasonal flu, hospitalization and death can occur. There have been documented cases of multiple people becoming sick after exposure to one or more infected pigs and also cases of limited spread of variant influenza viruses from person to person.

Human infections with a non-human influenza virus should be fully investigated to be sure that such viruses are not spreading in humans in an efficient and ongoing way, and to limit further exposure of humans to infected animals if infected animals are identified. At this time, the epidemiology of the human infections reported this week seems consistent with what has been in the past. None of the most recent infections were hospitalized, and there were no deaths. CDC is conducting laboratory studies to find out more about these viruses.

Agricultural fairs take place across the United States every year, primarily during the summer months and into early fall. Many fairs have swine exhibitions, where pigs from different places come in close contact with each other and with people. These venues may magnify the risk of spread of influenza viruses between pigs and people. The number of variant virus infections reported in humans has varied from season to season. During the summer of 2012, 309 human infections with H3N2v viruses were detected. Subsequently, 19 infections of H3N2v were detected in 2013, and only 3 infections each were detected during 2014 and 2015.

Some people are at high risk of developing serious illness from variant virus infections, just as they are from seasonal influenza. This includes young children, people with underlying health conditions like asthma, diabetes or heart disease, pregnant women and people who are 65 and older. In order to reduce the possible risk of serious illness to people posed by interactions between people and pigs at fairs, CDC recommends that people at high risk for serious flu complications avoid pigs and swine barns at fairs. During the 2012 H3N2v outbreaks, 16 people were hospitalized, and one person died from H3N2v infection. Most of those people were at high risk for serious flu complications.

The 2016-2017 seasonal flu vaccine is not formulated to provide protection against H3N2v. CDC recommends annual seasonal influenza vaccination for everyone 6 months and older to protect against seasonal flu viruses. The same influenza antiviral drugs used to treat seasonal flu can be used to treat variant virus infection in children and adults. The currently recommended drugs — oseltamivir, peramivir, and zanamivir — are available by prescription only. Early treatment works better and is especially important for people who are very ill or who are at high risk of serious flu complications.

Communicated by:
ProMED-mail
<promed@promedmail.org>

[The cases from Michigan mentioned in the above report have already been reported in the ProMED post “Influenza, swine (02): USA (MI) human case, H3N2v 20160807.4399461.” All the reported cases had history of exposure to pigs at fairs a few days prior to onset of illness.

It is important that the public be educated on specific exposures/risk behaviors in relation to swine that may lead to infection or risk of spread. Reinforcing the message for annual vaccination against human seasonal influenza, particularly in high risk groups, will also be helpful. – Mod.UBA

ProMED HealthMaps:
Ohio, United States: http://healthmap.org/promed/p/237
Michigan, United States: http://healthmap.org/promed/p/225]

See Also

Influenza, swine (03): USA (MI) 20160811.4408096
Influenza, swine (02): USA (MI) human case, H3N2V 20160807.4399461
Influenza, swine-origin (02): USA (WN, MN) H1N2v human cases 20160703.4323386
Influenza, swine-origin: USA (MN) human case, H1N2v 20160515.4222769
Influenza, swine: USA (MN,IA) study 20160114.3936806
Influenza, porcine – China: Eurasian avian-like H1N1 swine influenza virus, pandemic potential 20160102.3904985
2015
—-
Influenza, swine (05): USA (MI,MN) novel strains, human case H3N2v 20150905.3626427
Influenza, swine (04): USA (IA) novel strains H1N1v, H3N2v, human infection 20150830.3612253
Influenza, swine (03): USA, evolutionary dynamics IAV in swine, human threat 20150806.3562409
Influenza, swine (02): USA (MN) novel strains, human infection 20150804.3556121
Influenza, swine – USA: (MN) novel strains, human case H3N2v 20150726.3537522
2014
—-
Influenza, swine – USA: novel strains, H3N1, alert 20140916.2776180
2012
—-
Influenza (101): USA (OH), A(H3N2)v, swine to human transmission 20121026.1367194
Influenza (86): swine H1N2, virulence & transmissibility in ferrets 20120912.1291427
Influenza (85): USA: (MN) swine H1N2 influenza, human cases 20120911.1290389
Influenza (65): swine influenza, A/(H3N2)v, OIE status 20120806.1229963
2011
—-
Influenza (78): USA, swine-origin H3N2 reassortants update 20111224.3669
Influenza (74): swine-origin H3N2 reassortant, vaccine candidate 20111203.3526
Influenza (72): Europe, swine-origin H3N2 reassortant, risk assessment 20111130.3494
Influenza (71): USA (IA) swine-origin H3N2 reassortant, WHO 20111125.3448
Influenza (70): USA (IA) swine-origin H3N2 reassortant 20111124.3438
Influenza (69): USA (IA) swine-origin H3N2 reassortant 20111123.3430
Influenza (68): Hong Kong swine-origin H3N2 reassortant 20111119.3411
Influenza (66): USA swine-origin H3N2 reassortant, update 20111105.3298
Influenza (63): USA (ME, NOT NH) swine-origin H3N2 reassortant 20111102.3260
Influenza (60): USA (ME) swine-origin H3N2 reassortant 20111021.3134
Influenza (54): (PA) swine-origin H3N2 reassortant, comment 20110913.2789
Influenza (52): (PA), swine-origin H3N2 reassortant, 3 cases 20110906.2723
Influenza (51): swine-origin H3N2 reassortant, children 20110902.2685
2010
—-
Influenza (14): swine origin (tr) H3N2 viruses 20101112.4117
Influenza pandemic (H1N1), animal (07): Finland, swine, OIE 20100901.3114
Influenza pandemic (H1N1) (42): reassortment, swine 20100618.2055
Influenza pandemic (H1N1), animal (06): Korea, swine 20100422.1296
Influenza H3N2, new, swine, human – USA: (IA) 20100116.0189
Influenza pandemic (H1N1) 2009, animal (01): China, swine, canine 20100101.0014
2009
—-
Influenza pandemic (H1N1) 2009, animal (42): USA (NC) swine 20091228.4372
Influenza pandemic (H1N1) 2009, animal (41): Russia (CV) swine, OIE 20091226.4353
Influenza pandemic (H1N1) 2009, animal (39): Germany, swine, OIE 20091211.4220
Influenza pandemic (H1N1) 2009, animal (38): Mexico, swine, OIE 20091211.4214
Influenza pandemic (H1N1) 2009, animal (35): Italy, swine, OIE 20091205.4144
Influenza pandemic (H1N1) 2009, animal health (31): Finland, swine, OIE 20091201.4106
Influenza pandemic (H1N1) 2009, animal health (09): Indonesia, swine 20091127.4071
Influenza pandemic (H1N1) 2009, animal (22): USA, swine 20091106.3834
Influenza pandemic (H1N1) 2009, animal (19): Iceland swine, OIE 20091028.3737
Influenza pandemic (H1N1) 2009, animal (13): USA swine, conf. 20091020.3600
Influenza pandemic (H1N1) 2009, animal (12): USA swine, susp 20091019.3592
Influenza pandemic (H1N1) 2009, animal (09): UK (NI) swine, OIE 20090918.3280
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Influenza pandemic (H1N1) 2009, animal health (06): Canada, swine 20090828.3027
Influenza pandemic (H1N1) 2009, animal health (05): Austr., swine 20090826.2999
Influenza pandemic (H1N1) 2009, animal health (02): Austr., swine 20090820.2951
Influenza A (H3N2), swine, human – USA: (KS) 20090808.2812
Influenza pandemic (H1N1) 2009 (22): Australia (NSW), swine 20090801.2698
Influenza pandemic (H1N1) 2009 (15): Canada (AB) swine workers 20090723.2603
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Influenza A (H1N1): animal health (16), Argentina, swine, OIE 20090626.2322
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Influenza A (H1N1) – worldwide (50): swine immunity 20090528.1987
Influenza A (H1N1): animal health (10) swine, Canada, cull 20090514.1813
………………………………………….sb/uba/msp/mpp

Source:
A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases


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