In the last newsletter, i started to describe the viruses which affect the pigeon sport most at this time. Because of several observations and practical experiences which require more research, i talked first about the scientific data as far as the research goes, to continue with the more practical aspects and consequences of an infection with the variola virus.

I will describe the Herpes virus in the same manner. About two years ago, i dedicated some of my time to the herpesvirus. But the questions about this virus remain. That is why i'm revisiting this subject. In this newsletter i will talk about the scientific data so far. The next newsletter is about the more practical aspects and the consequences.

The herpesvirus

The herpesvirus among pigeons (DHV1) is starting to get more and more attention. It deserves the attention it gets from the pigeonlovers. The virus occurs (without any symptoms) among a lot of pigeons. This can be deduced through the specific antibodies in quite a lot of pigeons. It is estimated that at least fifty per cent of the pigeons have these antibodies. Thus over half of the pigeons are latently infected. Herpesviruses tend to 'retire' after infection of the host. In periods of stress can the virus regain its effectiveness. This would explain why most of the symptoms show when the resistance of youngster is down, for example after weaning and during training flights.

Sometimes older pigeons secrete this virus without showing any symptoms. These pigeons are known as a virus reservoir.

Disease progression

For a long time, people ignored herpesinfections among pigeons. The clinical cases of a pigeonherpesinfection are rare. Usually are the youngsters infected at an early age, especially during feeding, by the parent pigeons. They have enough resistance due to the antibodies received from the mother (maternal antibodies). That is why these pigeons won't show any clinical signs. But they are infected for the rest of their lives.

Clinical signs can be expected among pigeons who came into contact with the virus and who haven't got any antibodies. This could happen with recently bought youngsters placed with the youngsters of the pigeon fancier. The signs can appear after 5-7 days. When rapid cell multiplication occurs, the infection pressure can become so high that youngsters with few antibodies show symptoms and become sick. This way, the virus can remain active in the dovecot for a long time. With all of the consequences for the youngsters game season. The recovery of the herpesvirus can take from one week up to three weeks.

During stress situations, like basket transport, the carriers of the herpesvirus can secrete the virus. This will occur sooner if the resistance of the pigeon is low.

Research in Germany showed that in the month July there is a spike in the virus secretion during transport and the research showed that 60% of all manure samples are positive for the herpesvirus.

Especially young pigeons, two to ten weeks old, are most likely to show clinical symptoms. These symptoms vary quite a lot. From acute mortality with losses among the youngsters through to the more usual conjunctivitis, which we address as ' the membrane'. Traditionally, the herpesvirus is connected with the Coryza contagiosa complex (infectious snot).

Symptoms

If we recite the complete characteristics of the herpesvirus, you have to consider that these occur in only a limited number of cases. Often you can observe only a small section of these symptoms. Reaching the diagnosis 'herpervirusinfection' is hard with only a few observable, clinical symptoms. The most typical symptoms are a yellowish coated in the beak and pharynx. These coated are, in contrast to diphteric coated or coated from serious cankerinfections (which occur sporadically nowadays) as a loose membrane on the mucous membrane of the beak, tongue and pharynx. The virus affects primarily the upper-respiratory tract and the mouth- and throat cavity and the larynx, the crop and the esophagus. Because of the degradation of the crop, pigeons are having a hard time digesting their food, and it is causing the complete loss of their appetite. Although the syndrome occurs mostly among youngster, from two to ten weeks old, old pigeons can dhows signs as well. During serious outbreak, the mortality rate can be as high as fifty per cent, due to this virusinfection. But the seriousness of the occurring symptoms depends on the resistance of the pigeons and the virulence of the virus itself. This virulence varies quite a lot, so the seriousness of the symptoms vary as well. Often we encounter mild symptoms, which only shows through a membrane in the eyes.

Other diseases which show symptoms like coated in the beak, are canker, the smallpox-diphteria antitoxin and candidiasis. Sometimes you can detect dried mucous after a long flight. The smallpox-diphtheria antitoxin and canker have a rather cheese like ... coated and so they have a different diagnosis.

Because the majority of the herpesvirusinfection have a mild infection course, het role of this virus is more in the whole of the ornithosis-complex. Against the virus itself, you can do little. It there is a serious infection, you can treat the pigeon with preventive medication to support the pigeon in fighting of other additional infections. If the infected pigeons are award winning pigeons, you can treat these pigeons with Acyclovir for ten days to temper the infection and reduce the influence of the virus. You can't expect a panacea. To complete the support of the very sick and infected pigeons, you can use Marbocap and Synulox. In case of a herpesvirusinfection, you have to disinfect the dovecot with Koudijs-dry unblocker or Virkon S (let it soak).

In the next newsletter, i will describe the more practical consequences of this herpesvirus.

Good luck,

Peter Boskamp