Influenza H1N1 Outbreak in Humans
California, Texas and Mexico
Fact Sheet
April 27, 2009
This fact sheet is a summary of the background information and on the influenza virus that has been found in Texas, California and Mexico in March and April of 2009. The information contained is this document is believed to be correct based on the best currently available information but information can and does change daily that may warrant previous information incorrect.
Human Cases of Novel North American Influenza A(H1N1) 2009
The current Influenza H1N1 outbreak is a significant human health concern and has not been detected in livestock including swine. It is important to remember that influenza in humans is a constantly evolving disease which is estimated to kill 250,000 to 500,000 people worldwide every year. Department of Homeland Security Secretary Janet Napolitano declared a public health emergency in the United States. This declaration allows funds to be released to support the public health response both in the United States and other affected countries. Secretary Napolitano stated the following during her declaration – “Preliminary investigations have determined that none of the people infected with the hybrid flu had contact with hogs. This virus is different, very different from that found in pigs.”
The number of confirmed cases is changing rapidly and will certainly increase daily for some time. There are at least five states with reported outbreaks and four countries reporting laboratory confirmed human cases include Canada and Spain. Of the cases in the United States only one has required hospitalization and most have been very mild. In the case of more severe signs, the virus is sensitive to the antiviral drugs oseltamivir (“Tamiflu”, Roche) which the US has very large stockpiles available for use and zanamivir. The strains currently included in the human flu vaccine do not provide cross-protection to the currently circulating virus.
The virus currently infecting humans has never been found in pigs or any other species prior to this outbreak. At this point the virus is currently only known to be human-adapted and has only caused clinical disease in humans. Because of the lack of evidence of animal involvement the World Organization for Animal Health (OIE) is recommending that a more appropriate name for the virus would be “North-American influenza”. Despite the fact that the World Health Organization (WHO) continues to confirm that pork is safe to eat 5 countries (Russia, China, Philippines, Serbia, and Kazakhstan) have announced bans on some pork imports from the United States and Mexico.
Signs of Influenza H1N1 in people are very similar to the signs of regular seasonal human flu and include fever, cough, sore throat, body aches, headaches, and lethargy. Much like the seasonal flu, Influenza H1N1 in people is capable of causing disease ranging in severity from mild to severe. The virus typically spreads mainly from person to person through coughing or sneezing. Infected people generally shed the virus from 1 day prior to the development of clinical signs up to 7 days following recovery.
The National Pork Producers Council (www.pork.org) and the American Association of Swine Veterinarians (www.aasv.org) have provided a specific list of actions producers can take to respond to the current influenza outbreak. These recommendations can be found on the AASV Homepage. Click here to find these helpful facts.
Reliable information sources
In spite of media reports that there is no Influenza surveillance in US swine we have a VERY large network that has done a very good job of tracking trends in Influenza “strains” present in the NA swineherd. It is true that the USDA has not funded a surveillance project for pigs like CDC does for people but there is a large group of concerned veterinarians that have worked with the support of our clients to build a broad and deep database over the last 5 years. We have built this database not only to help make vaccine decisions for each individual company but to build a database so that we can respond with a high degree of confidence about what we know and what we don’t know to other scientists, health care providers and the media. Drs. Marie Gramer (U of Minnesota, VDL) and Amy Vincent (NVSL, Ames) have worked tirelessly to assist us in building this base of information and understand the Influenza viruses that are present in the NA swineherd.
Characteristics of Influenza H1N1 virus found in people in TX, CA and Mexico
We know the origin of each of the 8 gene segments and this is clearly a new re-assortment virus.
Cross species transmission of influenza virus
According to Dr. Greg Gray (U of Iowa School of Public Health) who has done research on human infections with swine influenza virus: “If the reports in Mexico are validated then this novel SIV virus seems to have increased transmissibility in moving from human to human. We just have no idea if it is transmissible from pig to pig or across species. As far as I know the novel virus has not been detected among pigs.”
There has been a human like influenza virus (H1N1) that has infected swine in North America. At least one commercial SIV vaccine (Flusure XP; Pfizer Animal Health, New York, NY) has included a similar virus.
Controlling influenza infection
April 27, 2009
This fact sheet is a summary of the background information and on the influenza virus that has been found in Texas, California and Mexico in March and April of 2009. The information contained is this document is believed to be correct based on the best currently available information but information can and does change daily that may warrant previous information incorrect.
Human Cases of Novel North American Influenza A(H1N1) 2009
The current Influenza H1N1 outbreak is a significant human health concern and has not been detected in livestock including swine. It is important to remember that influenza in humans is a constantly evolving disease which is estimated to kill 250,000 to 500,000 people worldwide every year. Department of Homeland Security Secretary Janet Napolitano declared a public health emergency in the United States. This declaration allows funds to be released to support the public health response both in the United States and other affected countries. Secretary Napolitano stated the following during her declaration – “Preliminary investigations have determined that none of the people infected with the hybrid flu had contact with hogs. This virus is different, very different from that found in pigs.”
The number of confirmed cases is changing rapidly and will certainly increase daily for some time. There are at least five states with reported outbreaks and four countries reporting laboratory confirmed human cases include Canada and Spain. Of the cases in the United States only one has required hospitalization and most have been very mild. In the case of more severe signs, the virus is sensitive to the antiviral drugs oseltamivir (“Tamiflu”, Roche) which the US has very large stockpiles available for use and zanamivir. The strains currently included in the human flu vaccine do not provide cross-protection to the currently circulating virus.
The virus currently infecting humans has never been found in pigs or any other species prior to this outbreak. At this point the virus is currently only known to be human-adapted and has only caused clinical disease in humans. Because of the lack of evidence of animal involvement the World Organization for Animal Health (OIE) is recommending that a more appropriate name for the virus would be “North-American influenza”. Despite the fact that the World Health Organization (WHO) continues to confirm that pork is safe to eat 5 countries (Russia, China, Philippines, Serbia, and Kazakhstan) have announced bans on some pork imports from the United States and Mexico.
Signs of Influenza H1N1 in people are very similar to the signs of regular seasonal human flu and include fever, cough, sore throat, body aches, headaches, and lethargy. Much like the seasonal flu, Influenza H1N1 in people is capable of causing disease ranging in severity from mild to severe. The virus typically spreads mainly from person to person through coughing or sneezing. Infected people generally shed the virus from 1 day prior to the development of clinical signs up to 7 days following recovery.
The National Pork Producers Council (www.pork.org) and the American Association of Swine Veterinarians (www.aasv.org) have provided a specific list of actions producers can take to respond to the current influenza outbreak. These recommendations can be found on the AASV Homepage. Click here to find these helpful facts.
Reliable information sources
- There is a daily update posted at http://www.cdc.gov/flu/swine/investigation.htm that presents the official update of the number of cases that have been confirmed.
- The international disease outbreak monitoring service ProMed is also a reliable source of information on the current state of the outbreak.
- Background information on Influenza H1N1 can be found at http://www.cdc.gov/swineflu/
- There are two main types of influenza viruses – Type A and Type B. Only Type A viruses commonly infect swine.
- The influenza virus has 8 separate gene segments that can recombine in any manner.
- These gene segments can “trade around” so you can get about any combination if a person or pig is infected with multiple viruses at the same time.
- Two of these gene segments are important for the immune system to “see “ the virus: the HA gene and the NA gene.
- We name influenza isolates based on which HA and NA gene segments they have– ie H1N1, or H3N2.
- There are many types of both the HA and NA genes but only H1 and H3 and N1 and N2 commonly infect pigs.
- We call isolates “Swine” or “Bird” or “Human” flu based on where the HA gene in the virus is normally seen.
- Birds are the “normal host” for flu so the genetic origin for all flu can be traced back to “bird flu”. The common “swine flu” H1 started as the human H1 in the 1918 pandemic virus. The “swine flu” H3 we believe originated in humans in the 1970’s and then was passed to pigs.
- We name “strains” of flu not only by their HA and NA type but by the other 6 genes as well. We keep them straight with the following naming convention.
- Subtype/Species they were found in/Location they were isolated from/Year/HA type NA type
- A/Swine/Illinois/2009/H1N1 - would be an example from an isolate that we had last week.
In spite of media reports that there is no Influenza surveillance in US swine we have a VERY large network that has done a very good job of tracking trends in Influenza “strains” present in the NA swineherd. It is true that the USDA has not funded a surveillance project for pigs like CDC does for people but there is a large group of concerned veterinarians that have worked with the support of our clients to build a broad and deep database over the last 5 years. We have built this database not only to help make vaccine decisions for each individual company but to build a database so that we can respond with a high degree of confidence about what we know and what we don’t know to other scientists, health care providers and the media. Drs. Marie Gramer (U of Minnesota, VDL) and Amy Vincent (NVSL, Ames) have worked tirelessly to assist us in building this base of information and understand the Influenza viruses that are present in the NA swineherd.
Characteristics of Influenza H1N1 virus found in people in TX, CA and Mexico
We know the origin of each of the 8 gene segments and this is clearly a new re-assortment virus.
- The HA gene (H1) is like a virus we have seen in the US for several years. It is most similar to the HA gene in the SW/Indiana/2000/H1N2 reference strain. This is a VERY common H1 subtype and the SIV vaccine that we give to sows and gilts contains a virus that has an HA gene that is similar to the IN00-H1 reference isolate. We would expect it to provide some cross protection against this new virus if pigs were exposed.
- The NA (N1) is like a virus from Korea that was found in pigs. We don’t know much about this N1 subtype as it has never been seen in the US before.
- The M gene is like a virus from Korea that was found in pigs.
- The other 5 genes are part of what Dr. Vincent has described as the “triple re-assortment internal gene cassette” as it contains genes from pigs, people and bird isolates. These internal genes are found in almost all swine influenza isolates in the US over the last couple of years.
Cross species transmission of influenza virus
Infection of People with Swine Like Influenza Virus
The CDC states on its website: “Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza that regularly cause outbreaks of influenza among pigs. Swine flu viruses do not normally infect humans, however, human infections with swine flu do occur, and cases of human-to-human spread of swine flu viruses have been documented. See General Information about Swine Flu. From December 2005 through February 2009, a total of 12 human infections with swine influenza were reported from 10 states in the United States. Since March 2009, a number of confirmed human cases of a new strain of swine influenza A (H1N1) virus infection in California, Texas, and Mexico have been identified. An investigation into these cases is ongoing. For more information see Human Swine Flu Investigation.” (http://www.cdc.gov/swineflu/)According to Dr. Greg Gray (U of Iowa School of Public Health) who has done research on human infections with swine influenza virus: “If the reports in Mexico are validated then this novel SIV virus seems to have increased transmissibility in moving from human to human. We just have no idea if it is transmissible from pig to pig or across species. As far as I know the novel virus has not been detected among pigs.”
There has been a human like influenza virus (H1N1) that has infected swine in North America. At least one commercial SIV vaccine (Flusure XP; Pfizer Animal Health, New York, NY) has included a similar virus.
Infection of pigs with Novel H1N1 swine like virus from TX and CA
Dr. KJ Yoon at Iowa State University said “There is no evidence yet that this virus cannot be handled by the current SIV vaccines. I presume that NADC/NVSL folks will test the CA virus on HI and SVN tests soon, so we would know more about this. Nonetheless, in a way I see, the virus contains HA gene similar to H1 SIV circulating in US swine. It is reasonable to believe then that current swine population may not go through any severe disease unless Eurasian NA or M gene products have great impact on the pathogenesis or cross protection (I doubt it). With the same reason, practitioners/producers would not experience terrible vaccine failure as HA is the most important part of vaccine-induced protection. Taking precaution is a good measure since influenza is a zoonotic disease, but we should not be panic over this particular virus yet.”Controlling influenza infection
There are two basic process to help control influenza infection:
- Hand Washing
- Covering your mouth when you cough
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We are now located in our new office at the former Carthage College - Anthony Hall.
Learn more about the history of our new office.
P's in a Pod
A monthly podcast brought to you by Pfizer Animal Health and Carthage Veterinary Service. P’s in a Pod covers practical tips on pigs, production and profitability. Access it here
Carthage Corner Newsletter
View a quarterly newsletter brought to you by Carthage Veterinary Service and Elanco Animal Health. Click here to view past issues.
Conference Proceedings
Get the proceedings from the 20th annual CVS swine conference held on August 31st, 2010 here.
Spanish Translations
We have fully qualified staff member for translation of information into Spanish. Learn more.
Records
The CVS Records Dept. offers records consulting services to the swine industry. Learn more.
Professional Partnership Award
Six agencies were honored with the state Professional Partnership Award. Included in the award are Carl Sandburg College, City of Carthage, Carthage Veterinary Service, Professional Swine Management, Prairieland Investment Group and Carson Motors.Read more.
The Food Animal Veterinarian Recruitment and Retention Program
The Food Animal Veterinarian Recruitment and Retention Program will provide financial incentives in the form of student loan debt forgiveness for veterinarians who commit to four years of employment in food animal veterinary medicine. Learn more.
Swine Disease Eradication Center
We are a member of the Swine Disease Eradication Center - University of Minnesota. This is a center dedicated to research in disease transmission and methods to eliminate. This center has led the industry in PRRS, Mycoplasma, and SIV aerosol transmission. Its research in filtration has redefined herd biosecurity.
Producers, Pigs, and Pork
Building for the future by working with the present. CVS has been reading the storybook "Producers, Pigs, and Pork" to elementary schools in West Central Illinois. This is a illustrated story of a boy's visit to a modern swine production facility. Learn more...
PRRS Elimination Project
Join us in our Tri-County Hancock, Adams, and McDonough PRRS Elimination Project!
Virtual Walking the Pens
A Wean-Finish 3D training simulation developed by CVS and ForgeFX and brought to you by Pfizer Animal Health. Download it for free at: www.virtualwalkingpens.com
Training Toolboxes
Over 60 multimedia computer training lessons on breeding, farrowing, and wean-to-finish production techniques available in English and Spanish.
Learn more...
Vet Internships
Interested in a vet internship with CVS. Click here to learn more.
Student Internships
