Herpesvirus

[bruno1]

Just Ask Me, this is the article on herpesvirus, bit on the long side:-

 

Understanding Herpes Virus in Pigeons

 

Dave Rupiper DVM

Kenneth T. Briggs DVM, PhD

 

Herpes virus, also known as Infectious Catarrh, is a contagious, persistent virus causing respiratory and neurologic disease in pigeons. In its breadth of clinical signs, occasional virulence and persistence in carrier birds, Herpes infections of pigeons somewhat resembles diseases caused by similar Herpes species in other domestic animals. (Fortunately, Herpes infections are very specific to their natural hosts -- we can't infect our birds with our varieties, nor can we contract the pigeon forms!) Birds having Herpes infections are often concurrently infected with Mycoplasma, Chlamydia (Psittacosis/Ornithosis) and bacteria.1 As a result, signs of disease may not always be straightforward. Herpes virus was first identified in pigeons in the U.S. in 1945 and in other countries during the next 40 years.2 Multiple types of Herpes virus affect other species such as raptors, waterfowl, psittacines and poultry.2,3

 

Herpes virus in pigeons may be of two or three different forms. The most common form, Pigeon Herpes Virus (PHV), may cause mild respiratory and liver diseases. Two strains of PHV have been isolated, mild and severe PHV.4

 

The second form, Pigeon Herpes Encephalomyelitis Virus (PHEV), may cause paralysis, torticollis (twisted necks and rolling) and other neurologic signs without causing respiratory signs, making it difficult to distinguish between PHEV and Paramyxovirus. Fortunately, PHEV has not been reported to be a significant problem in the U.S. but may be observed in birds imported from the Middle East.

 

The third reported form of PHV causes inflammation of the cloaca and vent but the distinctiveness of this form has not been confirmed.2

 

Etiology (Cause) and Transmission: Herpes virus belongs to a group of DNA viruses known as the Herpeviridae which includes the viruses which cause Marek's Disease of poultry, Duck Plague, psittacine Pacheco's disease, and Infectious Laryngotracheitis of chickens.5 PHV is usually passed from affected adults to squabs during feeding. It can be transmitted by nasal discharge as well as in saliva, feces and urine. In most flocks, PHV is already present but birds only manifest signs if the strain is severe, as with PHEV, or the birds are stressed by management problems and concurrent diseases.

 

Signs: PHV causes upper respiratory signs. These include reddening of the eye, cere and lids, nasal discharges, graying and filming of the mouth and oral cavity, and occasionally open-mouthed breathing. These respiratory signs and discharges are referred to as "catarrh." Other symptoms include fluffed posture, depression, diarrhea, weakness during flight and anorexia.

 

PHEV causes neurological signs such as paresis ( muscle weakness), paralysis, circling, seizures and twisted necks. PHEV is also much more severe than PHV and may result in rapid and high mortality within a loft.

 

Diagnosis: The classic diphtheritic (filmy slime in the mouth) upper respiratory signs are fairly diagnostic for PHV but may be confused with the "Ornithose Complex" involving concurrent infections of Mycoplasma and Chlamydia. Diagnosis is most easily achieved via necropsy (autopsy) of an affected bird. Special staining of the spleen and liver allows a pathologist to identify special inclusions within the cells which are called "intranuclear inclusion bodies" or "INI bodies." The liver and spleen often have tissues damaged with PHV.

 

Treatment: There is no cure for the disease and only through improved management can we hope to achieve control.6 Treatment with a drug called acyclovir may help control severe signs but the disease often returns if the medication is discontinued. It is best to allow Herpes virus to run its course and let the birds develop a natural immunity. Passive immunity (antibodies are transferred from parents to squabs in "crop milk") protects the young until weaned. Isolation of obviously affected birds is recommended since they are often infected with other contagious diseases as well.

 

Prevention: Killed and live virus vaccines have been formulated, but these only prevent shedding and dissemination of the virus from affected birds. Vaccines do not prevent pigeons from being carriers of Herpes virus.2,5 Natural infection of mild strains with subsequent immunity is still the best method to protect a flock from virulent strains of PHV.2

 

Like so many diseases of our birds, prevention and treatment often depend on cleanliness, good husbandry, good nutrition and preventing overcrowding. The days of keeping six inches of dry litter on the loft floor to prevent disease are gone, just as using NFZ to control canker and Paratyphoid is obsolete. Intense competition at shows, performance flying of young birds and increased production of squabs are placing more demands on the fancier in order to still be competitive. The key to success is educating ourselves about the disease process and by progressive management of our lofts.

 

 

References

1. Schrag L: Healthy Pigeons, 6th English Revised Ed, Hengersberg, W Germany, Schober Verlags-GmbH, 1989, pp 48-53.

2. Tudor DC: Pigeon Health and Disease, Ames, IA, IA St Univ Press, 1991, pp 34-38.

3. Fraser CM (Ed): Part VI, Diseases of Poultry. in Merck Veterinary Manual 6th Ed, Rahway, NJ, Merck & Co., Inc., 1986, p 1272.

4. Kaleta EF: A Selection of Disease Syndromes in Pigeons. Proc 1st Conf European Comm AAV, 1991, pp 77-81.

5. Dorrestein GM: Viral Infections in Racing Pigeons. Proc AAV, 1991, pp 244- 257.

6. Marshall R: Management of Pigeon Diseases. Proc AAV, 1990, pp 122-135.

 

[Guest Owen]

Thanks for that. Although I found it a bit frightening really. It seems that all it takes is for your birds to become infected somewhere for you to be in really bad trouble. It looks to me that, if you get this disease, you have little option other than culling all your birds. And to make matters worse, the symptoms resemble other nasty diseases. So it could be difficult to recognise.