Updated December 2006 The WSAVA would like to offer information of quality to the readers of the WSAVA web page. Since Avian Influenza, often termed bird flu, and the recently emerging Canine Influenza are front-page news items in both the veterinary and the human health press, not to mention the lay press, the WSAVA has selected for the readers of the WSAVA web page several articles and reference resources as well as summarizing key issues well worth the attention of veterinarians in companion animal practice. Infection of Cats with H5N1 Avian Influenza Virus The article on the infection of cats with H5N1 Avian Influenza virus is published by the European Advisory Board on Cat Diseases (ABCD). The article, which is written by world experts in the field of infectious diseases in cats, gives a complete update of what is known about avian influenza in cats. The information includes clinical signs, findings at necropsy, and ways of transmission of the virus, in naturally infected as well as experimentally infected felids. Read more:
(http://www.vetscite.org/publish/items/002817/index.html)
More information about the European Advisory Board on Cat Diseases can be found at Veterinary Sciences Tomorrow (http://www.vetscite.org/).
Updates on Avian Influenza in Poultry
Avian influenza represents one of the greatest recent concerns for public health. The number of birds involved in Avian Influenza has increased from 23 million during 1959-1998 to 200 million during 1999-2005. Recent outbreaks have led to devastating consequences for the poultry industry, negative repercussions on the public opinion, and created in some instances major human health issues, including the risk of generating a new pandemic virus for humans through an avian-human link. Guidelines on disease prevention and control have been issued as joint recommendations of the World Health Organization for Animal Health (OIE), the Food and Agriculture Organization (FAO), and the World Health Organization (WHO). To eradicate Avian Influenza, the vaccination system must allow the detection of filed exposure in vaccinated flocks, which can be achieved by using conventional inactivated vaccines and recombinant vector vaccines. Read more:
(http://www.cdc.gov/ncidod/EID/vol12no09/06-0430.htm)
Updates on the spreading of Avian Influenza around the globe may be found on several web sites. The information may be updated regularly and hence repeated visits to the sites are advised. One of the pathways to updated information is the site Flu Wiki. The link to the Geographic maps obtains an overview of infected areas. The following URLs will help you to visit the information:
(http://www.fluwikie.com/)
(http://www.fluwikie.com/pmwiki.php?n=Geographic.Geographic#Maps)
A site with well-updated news about Avian Influenza as an infectious disease generating a new pandemic virus through the human-avian link is to be found with the following link:
(http://www.cdc.gov/flu/avian/)
Researchers studying Avian Influenza say that they have agreed to share data that were previously being kept behind closed doors. Avian Influenza scientists have tentatively agreed to share data as part of an effort called the Global Initiative on Sharing Avian Influenza Data (GISAID). The data will at first only be accessible to scientist who have signed up to the agreement, but will become open to the public after 6 months at most. By storing all sequences in a designated place and allowing more open access, it is hoped that researchers will be able to quickly compare a new strain with many others from both animals and humans. This type of analysis can reveal whether a virus is acquiring mutations as it spreads between bird flocks. Read more:
(http://www.vetscite.org/publish/items/003164/index.html)
New Avian Influenza strain spreads fast, and is resistant to vaccine A newly discovered bird flu strain has emerged in China and has spread rapidly through poultry in Southeast Asia. Magnifying those concerns is the vaccine-selective nature of the new strain, which means that existing animal vaccines are less effective on it than they are on previously known bird flu types. Read more:
(http://news.nationalgeographic.com/news/2006/11/061101-bird-flu.html) Treatment of Influenza in the Event of a Pandemic Tamiflu (oseltamivir) is effective in reducing the risk of death associated with seasonal influenza in severely ill patients, according to new data. Treatment of infected adults was associated with a 71 per cent reduction in mortality. These results demonstrate the importance of the role of antivirals in the management of seasonal influenza and highlight the seriousness and risks of mortality associated with it. Tamiflu is designed to be active against all clinically relevant influenza viruses and works by blocking the action of neuramidase enzyme on the surface of the virus. When neuramidase is inhibited, the virus is not able to spread and infect other cells in the body. Read more:
(http://www.sciencedaily.com/releases/2006/09/060930094303.htm) American Veterinary Medical Association Avian Influenza Update December, 2006 A group of veterinary professionals has compiled a list of updated avian influenza (AI) facts that are broken down by audience, including consumers, human doctors and veterinarians. Representatives from American Animal Hospital Association participated in the industry workgroup that was organized by the AVMA and includes professionals from the American Association of Feline Practitioners, the American Association of Avian Pathologists, the Association of Avian Veterinarians, several federal government groups, and the National Association of State Public Health Veterinarians.
While this industry document focuses on frequently asked questions, the Centers for Disease Control and Prevention (CDC) awarded $11.4 million to four companies that will develop a faster diagnostic field test for the highly pathogenic AI H5N1 and other influenza viruses. The award was announced Dec. 4, 2006.
The tests could provide public health experts worldwide with critical information on the influenza viruses circulating and help monitor for viruses that could cause a global influenza pandemic, according to the CDC.
A total of 13 companies applied for the monies, which will be used to develop a point-of-care test to detect AI H5N1 that can be used by doctors and field epidemiologists. Existing tests detect seasonal influenza viruses but not the highly pathogenic AI H5N1 strain that has infected more than 250 people in 10 countries. Tests that are currently available require anywhere from four to 24 hours to obtain results, according to the CDC. Additional Articles The first article, published by the British Small Animal Veterinary Association (BSAVA), deals with Avian Influenza. The article emphasizes that there are many different strains of avian viral influenza, some of which having low pathogenicity while others are highly pathogenic. Some virus strains cause illness in poultry, others in wild fowl, and some are pathogenic for humans. It is also emphasized that an avian influenza virus could combine with a human influenza virus, resulting in a new virus against which humans have no immunity. All veterinarians should be well informed about how the risks should be interpreted, and this article is helpful in achieving this. The second article, published by the Journal of the American Veterinary Medical Association (JAVMA), deals with Canine Influenza, an emerging viral respiratory tract disease in dogs (click here to read full article). The disease is now emerging in the United States of America (USA) but since dog-to-dog transmission has been confirmed, the disease could be imported into other countries. The clinical signs of the diseases may mimic those of kennel cough and it is important that all companion animal veterinarians be aware of this, for this disease can be fatal, while kennel cough is not. The virus is the H3N8 strain of influenza virus. The article gives the latest information about the disease and is followed by the third article, also from the JAVMA, which is an update on the second article and is dated December 1, 2005 (click here to read full article). The fourth article is also about Canine Influenza and was published by the BSAVA . It presents key facts about the disease as it appears in the USA, followed by a report of experience with the H3N8 virus in the United Kingdom (UK). It was discovered there in 2002 in lung samples from foxhounds that had died of respiratory disease, and antibodies to the H3N8 virus were then demonstrated in the serum of dogs that recovered. This description of the experience in the UK will be valuable reading for all companion animal veterinarians who are not yet familiar with the disease. ____________________________________ AVIAN INFLUENZA INFORMATION FOR SMALL ANIMAL GP VETS LIKELY TO BE DEALING WITH SMALL/BACKYARD FLOCKS Key Points
Avian Influenza (AI) is a disease of birds, not humans. But humans can, rarely, be affected.
There are both high pathogenic (HPAI) and low pathogenic (LPAI) forms and many strains.
LPAI does not always show up as disease in birds. However, it is present in some areas of the global wildfowl population.
There is a constant but low risk of migrating birds bringing LPAI to the UK.
LPAI can mutate into HPAI, especially when introduced into poultry populations.
Some strains of HPAI spread easily between birds and cause illness, with a high death rate, very quickly in poultry populations.
In rare cases, some HPAI strains can lead to severe illness and deaths in humans where there has been close contact with infected birds.
There are a limited number of reported cases of human-to-human spread of AI. There is no such thing as a human pandemic of bird `flu.
Migratory waterfowl particularly wild ducks are the main known natural reservoir of avian influenza viruses. These birds are the most resistant to clinical disease and often show no clinical signs or mortality when infected.
It is possible for human and bird flu viruses to combine to produce a new human flu virus if a person is infected by both at the same time. That could produce a virus to which people have no current immunity and which could spread between humans.
It is therefore very important to ensure that any outbreak of AI is controlled quickly and that workers and veterinarians in close contact with infected birds are well protected. The Government has contingency plans in place to ensure that this is so.
The Government and key stakeholders are working closely together to ensure that the UK response to current circumstances is appropriate and comprehensive.
Key stakeholders (British Egg Industry Council, British Poultry Council and the National Farmers Union - which cover the bulk of the egg and poultry sector) share the Government's assessment that the risk of HPAI in this country remains present but low. They agree that no extra precautionary steps other than good vigilance and biosecurity are required at the moment.
Advice on worker protection is a matter for the Health Protection Agency.
There is no confirmed outbreak of HPAI in the UK at the moment. However, keepers of poultry will wish to be vigilant, to take care if handling birds which appear to be unwell and to observe high levels of biosecurity. Guidance is on the Defra website.
In the event of an outbreak, Defra will be able to protect its workers with the necessary drugs and equipment. Detailed instructions to staff are in place.
Surveillance is important in order that arrival of AI in the UK is rapidly detected.
The public is encouraged to report (not touch) dramatic local incidents large numbers of sick, dying or dead birds to the DEFRA hotline 08459 335577.
Clinical Signs
Typically the disease in poultry presents suddenly with affected birds showing oedema (swelling) of the head, cyanosis (purple/blue discolouration) of the comb and wattles, dullness, lack of appetite, respiratory distress, diarrhoea and drop in egg production. Birds may often die without any signs of disease being apparent. Death can occur so quickly that these signs may not be seen. Influenza therefore should be considered in the differential diagnosis of any significant unexplained mortality. There can be considerable variation in the clinical picture and severity of the disease. (Pictures are available on the DEFRA website at: http://www.defra.gov.uk/animalh/diseases/notifiable/pictures/avianinfluenza.htm)
Biosecurity for free-range, exhibition and small scale poultry
Keep feed under cover to minimise wild bird attraction.
Keep water fresh and free of droppings.
Keep waterfowl and chickens separate.
Control vermin.
Quarantine new stock for 2-3 weeks.
Quarantine birds for 7 days after taking to an exhibition.
Change clothes and wash boots before and after visiting other breeders.
Change clothes and wash boots before and after attending a sale.
Keep fresh disinfectant at the entrance to poultry areas for dipping footwear.
Disinfect crates before and after use, especially if lent to others. However, it is preferable not to be sharing equipment.
Disinfect vehicles, which have been on poultry premises but avoid taking vehicles onto other premises.
Comply with any import/export regulations/guidelines.
Wash hands before and after contact with birds.
Discourage people from attending bird or poultry shows in Europe.
Note: The range of approved disinfectants for avian use may be found on the DEFRA website (www.defra.gov.uk) Guidelines issued on behalf of The Poultry Club of Great Britain
Victoria Roberts BVSc MRCVS
Honorary Veterinary Surgeon to The Poultry Club of Great Britain Source: BSAVA with permission to the WSAVA
______________________________________ CANINE INFLUENZA The virus
Family: Orthomyxoviridae enveloped viruses with segmented RNA genomes
Genus: Influenzavirus A
Serotype: H3N8
Key facts in the USA
The virus currently giving rise for concern is an equine influenza H3N8 which appears to have crossed the species barrier to infect dogs in the USA.
In dogs, the disease was first identified in Jan 2004 as an outbreak of unexplained respiratory disease in racing greyhounds in Florida.
Following infection, approximately 80% of dogs develop mild disease (mild pyrexia, nasal discharge, cough lasting 10-21 days), 1-10% develop a more severe and sometimes fatal pneumonia (high fever, dyspnoea, lung consolidation), with the remaining animals apparently developing an asymptomatic infection.
Since the first outbreak in Jan 2004, subsequent outbreaks occurred at racing greyhound tracks in many states in the USA.
Evidence for infection is now found in the general dog population in animal shelters, boarding kennels, pet shops and vet clinics. The exact geographic distribution of the virus is unclear. Most infection still seems to be limited to Florida and New York State. However, more recently, antibody has been detected in other states. This distribution may reflect the location of interested Vet schools.
The incubation period is around 2-5 days. Animals appear to shed virus for 7-10 days after onset of clinical signs.
Treatment is with broad-spectrum bacteriocidal antibiotics to control secondary bacterial infections and supportive IV fluids where necessary.
Control. There are currently no vaccines for canine influenza although one is being developed. Control is therefore based on a common-sense approach of quarantining dogs with respiratory disease and disinfection. If animals do have mild respiratory symptoms, animal owners are being asked to limit contact between their dogs and other dogs.
Diagnosis is by a paired (acute and convalescent) antibody test to demonstrate rising antibody titres and is available at Cornell Veterinary School, Wisconsin Veterinary Diagnostic Laboratories and the Animal Health Trust (AHT), UK.
Molecular studies suggest there was a single transmission event from horses to dogs in the USA and that now the virus is being transmitted directly from dog to dog. The time of this introduction is unknown although antibodies have been identified in serum from dogs in 2000.
The route of transmission which allowed equine influenza virus to get into dogs is unknown it could be from direct contact between an infected horse and susceptible dogs or from feeding untreated meat (including respiratory tissue) from a horse that was infected with equine influenza virus.
These cross species infections are extremely rare but are obviously topical at the moment in relation to human / avian influenza.
Canine / equine influenza H3N8 poses no known threat to human health. The virus has already been present in horses for 40 years and has never been associated with human disease. This may reflect differences in receptor specificity between equine and human influenza viruses that may limit the ability of equine influenza viruses to establish infection in human respiratory epithelium. Key facts in the UK
Having heard about the USA outbreaks, workers at the AHT in the UK undertook a retrospective analysis of an outbreak of unexplained respiratory disease in foxhounds in Essex UK, in September 2002.
Lung samples from these dogs tested positive for H3N8 virus.
Antibodies to H3N8 virus were found in serum samples from hounds that recovered from infection during the 2002 outbreak.
How prevalent is canine influenza in the UK? There are no current reports of similar outbreaks of fatal respiratory disease as reported in the USA. The AHT has tested approximately 300 serum samples from UK dogs and this suggests that equine influenza is not currently circulating in the UK pet dog population.
It is not known whether the outbreak in the UK was introduced from the USA or whether this represents a separate / novel introduction of virus from horses to dogs.
As dog-to-dog transmission has been established to occur in the USA, there is a possibility that the virus could now be introduced into the UK with influenza-infected dogs entering the UK under the Pet Passport Scheme.
Additional resources
BSAVA Update November 2006 Flu Wikie University of Florida fact sheet on canine influenza
http://www.vetmed.ufl.edu/pr/nw_story/CANINEFLUFACTSHEET.htm USA CDC Media briefing on canine influenza
http://www.cdc.gov/od/oc/media/transcripts/t050926.htm Animal Health Diagnostic Center, Cornell University
http://www.diaglab.vet.cornell.edu/issues/civ.asp Published online
Science online publication 26 September 2005.
Transmission of Equine Influenza Virus to Dogs. PC Crawford et al.
Source: BSAVA with permission to the WSAVA
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