Do Birds Spread Diseases?

The PiCAS group receives thousands of enquiries every year about bird control and yet the most common question is – do wild birds transmit diseases to human beings? The answer is no, wild birds do not transmit diseases to human beings. The likelihood of a bird passing on a disease to a human being is so infinitesimally small that it is not even worth considering. However, the commonly held view is that pigeons and other wild birds pose a massive threat to human health and as a result their numbers should be strictly controlled. So what is the source of this myth? The pest control industry.

Pest control is a multi-billion dollar industry worldwide where killing pigeons and many other so-called pest species of birds represents a large proportion of the profits generated within the industry. If the pest control industry was to cease using lethal control (culling) services tomorrow many pest control contractors would go out of business immediately, so dependent are they on this source of income. As a result of this, and in order to keep a dying industry alive, pest control companies pump out huge volumes of propaganda each year designed to scare the general public into buying pest control services and products. Why does the industry need to do this if its services are so effective? Because the most commonly offered service, culling, is not only highly profitable but it is also completely ineffective as a method of controlling or reducing flock size. Scientific research* and research carried out by independent and professional bodies, like the PiCAS Group has proven, conclusively, that killing pigeons and other so-called pest species of birds is not only completely ineffective as a control option but it is also counter-productive. The pest control industry needs to perpetuate the myth that killing birds is an effective control option in order to survive in a fast changing world that no longer embraces the concept of ‘if it moves, kill it’.

Scientists and bird control experts worldwide all agree that there is no tangible risk from contact with wild birds or their excrement. Below are quotes from leading experts in respect of the potential for pigeons to transmit disease to human beings:

• Mike Everett, spokesman for the Royal Society for the Protection of Birds said, in
   The Big Issue Magazine, February 2001: "The whole 'rats with wings' thing is just
   emotive nonsense. There is no evidence to show that they (pigeons) spread
   disease.”

• The UK’s Chief Veterinary Officer, when addressing the House of Lords in 2000 on
   the issue of intimate human contact with the then 7,000-8,000 pigeons feeding in
   Trafalgar Square, was asked if this represented a risk to human health. The Chief
   Veterinary Officer told The House that in his opinion it did not.

• Charlotte Donnelly, an American bird control expert told the Cincinnati
   Environment Advisory Council in her report to them: "The truth is that the vast
   majority of people are at little or no health risk from pigeons and probably have a
   greater chance of being struck by lightening than contracting a serious disease
   from pigeons."

• Guy Merchant, Director of The Pigeon Control Advisory Service (PiCAS
   International) says, when talking about the transmission of disease by pigeons:
   "If we believed everything we read in the media about the health risks associated
   with pigeons, and the farcical propaganda distributed by the pest control industry,
   we would never leave our homes. The fact of the matter is that there is probably
   a greater risk to human health from eating intensively farmed supermarket
   chicken and eggs, or having contact with domestic pets such as cats, dogs and
   caged birds, than there is from contact with pigeons."  

• David A Palmer (B.V.Sc., M.R.C.V.S) said in an article entitled 'Pigeon Lung
   Disease Fatality and Health Risk from Ferals': "Obviously, since all these Allergic
   Extrinsic Alveolitis disease syndromes rely on the involved person having a very
   specific allergy before any disease, involving respiratory distress and very
   unusually death, can possibly be seen, it really makes absolute nonsense for a
   popular daily newspaper to suggest that pigeons present a health hazard and
   presumably need eliminating for the well-being of the nation’s health.”

• David Taylor BVMS FRCVS FZS: “In 50 years professional work as a veterinary
   surgeon I cannot recall one case of a zoonosis in a human that was related to
   pigeons. On the other hand I know of, and have seen, examples of human
   disease related  to contact with dogs, cats, cattle, monkeys, sheep, camels,
   budgies, parrots, cockatoos, aquarium fish and even dolphins, on many
   occasions.”

• The Center for Disease Control in Atlanta, the New York City Department of
   Health, and the Arizona Department of Health all agree that diseases associated
   with pigeons present little risk to people. “We have never documented a pigeon to
   human transmission in the state of Arizona,” said Mira J Leslie, Arizona’s state
   public health veterinarian.

• In response to questions about the effects of pigeons on human health, in 1986
   the Association of Pigeon Veterinarians issued a statement that concludes, "…to
   our knowledge, the raising, keeping, and the exercising of pigeons and doves
   represents no more of a health hazard than the keeping of other communal or
   domestic pets."

Many professions, such as those involved in veterinary medicine and wildlife rehabilitation, treat wild birds suffering from a variety of avian diseases on a daily basis. Those involved in the sport of racing pigeons also spend a great deal of time in dusty pigeon lofts that accommodate hundreds of pigeons. If the potential for the transmission of disease is so great why is it that we do not see regular human fatalities in these professions and sports where close contact with birds such as pigeons is commonplace? Because pigeons are no more likely to transmit a disease to a human being than a pet cockatiel or a garden bird such as a blackbird or robin. All animals and birds have the potential to carry and transmit diseases, including human beings, but we don’t kill people or pets because they have the potential to transmit a disease.

There are only two circumstances where pigeons may be considered to represent a threat to human health: where excrement from roosting pigeons has fallen to pavement areas below causing a slip hazard and where pigeons roost in large numbers and pigeon excrement accrues as a result. Large quantities of well-dried pigeon excrement, when disturbed and breathed in, can cause irritation to the bronchial tubes but nothing more. If the dust is breathed in by someone with a pre-existing respiratory condition the effects can be more serious but the chance of anyone with a serious respiratory condition being exposed to this type of risk is virtually nil.

The issue of disease being transmitted to humans by birds has recently been highlighted worldwide by the avian influenza epidemic. The root cause of this disease, as with so many animal and bird-related diseases, was found to be intensive farming, particularly poultry farming. Intensively farmed birds such as chickens and turkeys are housed in appalling and cramped conditions where standards of hygiene are non-existent. In these conditions birds have to be fed large doses of antibiotic drugs just to keep them alive long enough to be killed for meat. Infection amongst birds housed in these conditions is rife even so. It therefore comes as no surprise to learn that diseases such as salmonella, often wrongly associated with the pigeon, is regularly transmitted to human beings through supermarket poultry and eggs from battery farms. Even in light of this clear connection between the transmission of diseases like salmonella and avian influenza from intensively farmed poultry to human beings, and the lack of any evidence to connect the pigeon with the transmission of these diseases, the pigeon was immediately identified as being a potential source of transmission to humans. The pest control industry made much of the connection as did the media, both for commercial gain. However, the pigeon was found to be highly resistant to all strains of avian influenza and yet this fact was never reported – it was in nobody’s best interest to do so.

The following research programmes confirm that the pigeon is, far from being a disease carrier, a bird that is highly resistant to disease:

Research into Highly Pathogenic H5N2 strain, 1983/4, North-Eastern USA:

A research programme was undertaken in the north-eastern United States in 1983/4 to assess the spread of the highly pathogenic strain (HP) of avian influenza (H5N2) by wild birds on local farms. A total of 4,132 birds were tested including a sample of 473 pigeons, 92.6% of which came from farms that had suffered an outbreak of HP H5N2. The feet of a further sample of 81 dead pigeons were assessed. The feet of pigeons were assessed because the birds had been in direct contact with the faeces of infected animals. Of the 4,132 birds collected and tested, not one tested positive for HP H5N2.

Further evidence that infection had not occurred in pigeons came from blood samples taken from 433 birds. Not one of the pigeons tested was found to have antibodies in their blood. Further experimental trials were undertaken to infect pigeons with HP H5N2 strain and no evidence was found to suggest multiplication of the virus or antibodies in the blood. This research found that the highly pathogenic H5N2 strain of avian influenza did not occur naturally in pigeons nor could the birds be infected with it and therefore concluded that pigeons could not spread the disease.

Research into Avian Influenza, 1992, USA:

Between February and May 1993 another outbreak of avian influenza occurred in the United States. A total of 160 pigeons were taken from flocks in the infected area. The flocks ranged in size from 2,000-3,000 birds. The 160 birds were taken from 17 different feeding flocks. Not one single pigeon tested positive to avian influenza.

Research into the Susceptibility of Wild Pigeons to Avian Influenza, 1996:

In 1996 another research programme was undertaken to assess the susceptibility of pigeons to avian influenza. Two groups of pigeons were infected; one with highly pathogenic avian influenza virus and the other with non-pathogenic avian influenza virus. None of the birds tested, for either virus, were found to shed the virus nor did they develop antibodies. Conclusive evidence that pigeons play no part in the spread of avian influenza.

Experimental Research into H5N1 (Hong Kong origin) in 2001/2002:

In this research pigeons were infected with the highly pathogenic form of the avian influenza virus H5N1 originating from Hong Kong. All the pigeons tested failed to demonstrate or develop any symptoms of the virus. Neither were there any detectable changes in their tissues in response to the virus. The virus was not present in tissue samples and neither could it be re-isolated from swabs of tissues. Other species involved in the research were starlings, rats and rabbits and all were found to be resistant to the virus.

In summary, these research programmes offer conclusive evidence that pigeons play no part in the spread of avian influenza and as a result are highly unlikely to be instrumental in the spread of any other type of virus or disease. Although pigeons have no potential to spread avian influenza several other species of wild birds, mainly waterfowl, were found to be carriers of the avian influenza virus and these included swans. Although swans live in close association with man and are a much loved and highly protected species, neither the pest control industry nor the media called for swans to be killed en masse just because they harboured the potential to infect human beings. Yet, during the avian influenza outbreak, both the media and the pest control industry made much of the danger posed by the pigeon and called for extensive culling of pigeon flocks. The reality is that pigeons, and most other so-called pest species of birds, are easy commercial targets that pose no threat whatsoever to human beings.

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