INTRODUCTION

This "disease" has become the scourge of fanciers throughout the world. Here we look at some of the theories and suggested solutions. We hope they will give food for thought and even make sense -  but you are reminded that they are only theories and suggestions.

SOME   SYMPTOMS   OF   YOUNG  BIRD   SICKNESS

Initially there seems to be a lack of appetite and some vomiting. Mucoid (watery) droppings are typical. Pigeons 'lose interest' in flying and may be seen sitting there with its crop full of water. They close their eyes as much as they dare in order to conserve fluid. Producing fluid droppings without being able to get water from the crop into the intestinal tract leads inevitably to dehydration. Being unable to absorb nutrients through the gastrointestinal tract leads to a shortage of energy which the pigeons try to retain by fluffing its feathers for increased insulation. Any available carbohydrates in the form of glycogen, then fat, and finally muscle tissue are burned for providing energy to stay warm. Almost no breast muscle will be left as the pigeons  becomes completely emaciated.

Many eminent medical experts suggest that one of the root causes is Adenovirus.

ADENOVIRUS   IN   HUMANS

Named after having been isolated from the adenoid tonsils of children,  in humans, it is a group of viruses that infect the membranes (tissue linings) of the respiratory tract, the eyes, the intestines and the urinary tract. They were first isolated in 1953 by investigators trying to establish cell-lines from adenoidal tissue.

Adenoviral infections affect infants and young children much more frequently than adults. There are forty-nine immunologically distinct types that can cause human infection.

Adenoviruses most commonly cause respiratory illness; however, depending on the infecting serotype, they may also cause various other illnesses, such as gastroenteritis, conjunctivitis, cystitis, and rash illness.  Symptoms of respiratory illness caused by adenovirus infection range from the common cold syndrome to pneumonia, croup, and bronchitis.

Most infections are mild and require no therapy or only symptomatic treatment - treating symptoms and complications of the infection.

Adenoviral illnesses often resemble certain bacterial infections. Bacterial infections  can be treated with antibiotics, but antibiotics don't work against viruses.

ADENOVIRUS   IN   PIGEONS

One point of view is that Adenovirus itself does not seem to cause disease in pigeons, except that it allows other, normal bacterial inhabitants of the intestinal tract to invade the bird's body and cause disease. Adenovirus "opens the door" to infection by bacteria, most notably Escherichia coli - E.coli. It is then thought that the E.coli causes the symptoms such as initially a lack of appetite and later the  vomiting and a general shutting down of the gut.

ADENOVIRUS  AND  E. COLI

As Dr. David Marx DVM explains:  "E.coli is a normal inhabitant of the digestive system of pigeons. It has disease potential, but usually needs a predisposing condition to allow it the opportunity to cause infection. Stress, viral infections, intestinal parasites and other irritants of the bowel are examples of such predisposing conditions. Thus adenovirus by itself will not cause disease, but in the presence of E.coli, it allows the E.coli to cause disease. Treating the E.coli infection usually eliminates symptoms although it does nothing for the adenovirus infection; this is usually conquered by the bird's own immune system with time. There is not an effective vaccine for adenovirus, so we must just let it run its course as we try to control the E.coli during outbreaks.

Usually during outbreaks of colibacillosis (E.coli infection), we use a broad sprectrum antibiotic such as Amoxicillin to control it. Antibiotics will not prevent it, so use them only during an outbreak. Amocicillin is gentle on the pigeon and is the least expensive of the good antibiotics. Use three grams per gallon for about seven days. Do not forget not to use antibiotics as a preventive. They will not work as a preventive, but will only allow the bacteria to become resistant to it, and then it won't work when we really need it."

ANOTHER  VIEW   ON   ADENOVIRUS

Dr. Carlo Gyselbrecht is a well-known expert on pigeon health in Belgium, and this is what he has to say on the matter:

"When the well-known adenovirus in the past could only be found with young pigeons (adenovirus Type I or 'classical adenovirus'), in more recent years it also occurs with old pigeons (adenovirus Type II or 'necrotising hepatitis').More than twenty years ago the classical adenovirus Type I was found in our regions; since then it has been described worldwide. The worst form, the adenovirus Type II has only been found since 1992 (also for the first time in Belgium). The main difference  is that old pigeons can be infected by Type II.

AdenovirusType I infects, as stated earlier, especially young pigeons. Because the intestinal wall is seriously damaged by it, germs that normally live in the intestine get the chance to proliferate enormously; in this way they probably damage the intestinal wall even more and can enter the blood circulation. The typical symptoms of adenovirus Type I are; the illness occurs very sudden and typical is vomiting heavily, diarrhoea, a very bad condition in general, and there's a very fast infection - within three to five days. Additional E.Coli infections will make the disease last longer - so its of the utmost importance to treat these additional infections as quickly as possible! The recovery of the pigeons can take some time, probably because of the slowly recovering liver-cells.

Adenovirus Type II is capable of causing massive liver necrosis. There are few symptoms - sometimes vomiting and yellow diarrhoea - as the pigeons can die within a few days.  Only by autopsy  and investigation of the intestinal wall and liver can the cause of death be confirmed, and parathyphoid, hexamythiasis, streptococcus, acute colisepsis etc. rules out.

As for dealing with the adenovirus - there is no efficient vaccination available. Whenever you find Type I in young pigeons, it is absolutely necessary to treat the secondary E.Coli infections as fast as possible. Avoid stress - transport, training, racing etc. For adenovirus Type II, the general rules are hygiene, ventilation, avoiding overpopulation - these are essential to keep the risk of infection as low as possible."

....... / to be continued.