Adenoviral, E.coli and Paratyphoid Infections in Pigeons      
Written by Derek Rooney   
Saturday, 03 February 2007

Adenoviral, E. coli and Paratyphoid Infections in Pigeons

byGordon A Chalmers, DVM
Lethbridge, Alberta, Canada
Email: Dr. Gordon ChalmersThe occurrence of adenovirus and its combination with the bacterial organism E.coli (the shortened form of its longer scientific name, Escherichia coli) has been causing grief to fanciers in many parts of the world today, especially in youngsters as they begin mixing with those from other lofts during the racing season. This is a highly stressful time for these birds, and because their immune system is often not completely developed at this stage of their lives, they are susceptible to any number of infectious agents. As well, in response to the stresses imposed by crowding, training and racing, etc., their adrenal glands, located just ahead of the kidneys, right under the vertebral column, release corticosteroids into the circulating bloodstream. These steroids depress the ability of the incompletely developed immune system to respond effectively to invading agents such as bacteria, viruses and parasites. One unhappy consequence of this depressed situation may be infection with adenovirus and a disease-producing strain of E. coli, which together, can bring about signs of illness characterised by vomiting and diarrhoea (Young Bird Sickness). Vomiting may be difficult to evaluate since it can occur during the night, and by dawn, other youngsters in the loft may have eaten the disgorged grains. In other instances, digestion is slowed and affected youngsters may retain feed in their crop ("holding their corn").

The following section is a brief summary of some aspects of these infections.

 

  1. ADENOVIRUS. In Europe, two different adenoviral infections are known to occur in pigeons, and are designated Types I and II. Type I was discovered in 1976, and occurred in young pigeons during the first half of the year, with a peak frequency in June. The major sign of this adenoviral disease was watery diarrhoea. E.coli often complicated this disease, and resulted in a more severe diarrhoea, as well as vomiting and occasionally, death. Treatment with appropriate antibiotics was often successful. At post mortem of affected birds, there was evidence of enteritis (inflammation of the intestines), and the liver was often normal or only mildly abnormal. However, microscopically in the liver, there were characteristic changes that indicated adenoviral infection. Type I adenoviral infection seems likely to be the disease that affects many young birds over the world today.
    Type II adenoviral infection occurred in Belgium in 1992, and was characterised by sudden death in pigeons of all ages. There were very few clinical signs in affected birds prior to death. Occasionally, there was fluid, yellow diarrhoea and vomiting. However, the major sign was sudden death within 24 hours of the onset of illness, with none of the obviously sick birds surviving longer than 48 hours. Antibiotics had no effect on the outcome of this disease. In individual lofts, losses were variable, and usually amounted to 30%, but in some cases reached 100%. At post mortem, affected birds had a pale, yellow, swollen liver that had a characteristic red sheen. Microscopically, there was massive destruction of the liver, along with typical changes indicative of adenoviral infection. Although this infection began by affecting one age group in a loft, in 70% of cases, the disease eventually spread to all age groups. To the surprise of investigators, in lofts in which these acute deaths occurred, pigeons that did not die remained completely normal. Even youngsters in the nest grew normally after their parents died of this infection, if they were able to feed themselves or were raised by other pairs. Whether Type II infection has yet occurred in other areas of the world is not known to me.
    In my experience with other species of domestic birds and animals, adenoviral infections usually occur when immune function is depressed. For example, in young, growing broiler chickens, infection with a virus known as the agent of Infectious Bursal Disease severely damages the immune system, thus allowing for the invasion of another virus, this one an adenovirus, that causes a disease known as Inclusion Body Hepatitis. Fortunately, a vaccine developed against the Bursal Disease virus has been effective in preventing Inclusion Body Hepatitis. In another example, some Arabian foals are born with an inherited condition known as Combined Immunodeficiency Disorder in which the immune system is severely underdeveloped. Massive adenoviral infection, especially a pneumonia, is often associated with the death of these foals.
    In pigeons, I continue to wonder about the largely hidden effects of circovirus infection which, like the AIDS virus in humans, causes severe damage to the immune system, and thereby, acts as a "trigger" that sets in motion, the further destructive effects of adenoviral and E. coli infections. Circoviral infection in pigeons could have an effect similar to that of the virus of Infectious Bursal Disease in chickens, ie severe damage to the immune system followed by invasion of the adenovirus and E.coli. One of the characteristic "footprints" of circoviral infection is an upsurge in outbreaks of other conditions - canker, coccidiosis, paratyphoid, etc., so it would be reasonable to include adenoviral -E. coli infections in that list of possibilities..
    Treating adenoviral infections is difficult, if not impossible. Unlike bacteria, viruses are not susceptible to antibiotics. However, in recent months, the use of elderberry juice in treating affected youngsters, has been touted as a method of dealing with this infection. Although I am not certain of any scientific basis for this claim, it may be worth examining.
    At least one adenoviral vaccine has been offered for sale in Europe and North America. One prominent veterinary friend whom I contacted about this vaccine observed that the results of vaccination in his area were mixed, likely because many fanciers didn't follow through with the required second (booster) vaccination, which, by extension, likely didn't allow for the development of a sufficiently high level of immunity to protect exposed birds.
    Perhaps the only practical approach is planned exposure to the virus, which could be accomplished through early mixing of young birds from different lofts in say, club training tosses, etc., well before the racing season, to allow them to go through the infection and develop protective immunity that would carry them though the race season. The use of the dewormer known as levamisole has been shown to stimulate the immune system, and according to Dr John Kazmierczak of New Jersey, USA, a dosage of 50 mg per 4 litres of drinking water once a week, may be helpful. Also, the use of a multivitamin mix containing vitamins C and E in the drinkers once or twice a week is practical and provides additional support to the immune system. A wide-ranging loose mineral mix containing the trace mineral selenium, which is important in the normal development of the immune system, should be available free-choice all year long.
     
  2. E. COLI. Broadly speaking, E. coli are usually innocent, normal inhabitants of the intestines of many species, including humans. However, like other creatures, E. coli organisms exist in Nature as a number of strains that range from the most innocent through to the most deadly. Some dangerous strains of E. coli in the intestines may cause disease by their production of potent toxins (poisons) that are absorbed through the intestinal wall into the bloodstream, from which their far-reaching effects in many tissues throughout the body are manifested. I suspect that the E. coli strains that are part of the adenoviral-E.coli problem in youngsters these days are toxin-producing strains. Still other dangerous strains of E. coli are able to breach the intestinal wall, enter the bloodstream where they multiply (called "septicaemia") and are distributed to a variety of tissues to produce signs of illness. Some joint, brain and ovarian infections, etc. in pigeons are caused by these tissue-invasive strains of E. coli. Like other creatures, humans are not exempt from the effects of dangerous strains of E. coli. Improperly cooked hamburgers containing a hazardous strain of E. coli have caused serious illness and death in humans. Two years ago, in Walkerton, Ontario, Canada, seven people died and over 1200 individuals in the town became seriously ill after they were exposed to a deadly toxin-producing strain of E.coli identified as 0157 that contaminated municipal drinking water.
    Some strains of E.coli recovered from sick domestic birds and animals may be specifically identified by the use of specialised laboratory techniques, such as those that identified the aforementioned strain of E. coli in humans as 0157. In other examples, young pigs with diarrhoea may have a strain of E. coli identified in part, as K88, and young calves with a similar problem may be affected by a strain identified in part, as K99. However, I am not aware if these or related procedures have been used commonly in the UK to identify disease-producing strains of E. coli in pigeons.
    In pigeons, as in many other species, the mere finding of E. coli organisms in a sample of droppings cultured in a laboratory does not necessarily mean that they are the cause of a problem. They could be completely innocent. For example, if samples of droppings are collected several hours after they have been passed, and if these samples have not been refrigerated during shipment to the laboratory, E. coli organisms that are present in these droppings can multiply during transit and, on culture, result in large numbers that may give the false impression that they are the cause of the problem. However, if freshly passed samples of droppings are collected quickly, refrigerated immediately, and kept refrigerated on route to the laboratory, there is a greater chance that large numbers of organisms cultured from these droppings may well be significant, especially if those large numbers can be tied to the problem being experienced in the birds. If a pure culture of E. coli organisms is recovered from a variety of tissues (heart blood, liver, kidney, etc.) from a freshly killed sick bird, there is a strong likelihood that they are the cause of that particular problem. Fanciers should ask for and expect an interpretation of the laboratory findings of E. coli (or any other significant organism cultured) found in submitted samples. However, if the fancier hasn't properly collected, refrigerated and shipped specimens to the laboratory, it becomes very difficult for laboratory staff to provide useful interpretations of their findings. An advance phone call to the laboratory for instructions on collecting, handling and shipping samples of droppings or other specimens, is a always good idea.
  3. PARATYPHOID.
    The paratyphoid organism found in pigeons is usually, but not always, Salmonella typhimurium variety copenhagen. In fact, in the experience of Dr Gerry Dorrenstein of Holland, 94% of the strains of paratyphoid organisms his group has recovered from pigeons, are variety copenhagen. This variety seems to be almost specific for pigeons, although occasionally, it has been found to cause disease in chickens.
    Like other birds and animals, most pigeons exposed to paratyphoid infection recover completely, either through treatment or natural defensive mechanisms, but as in the case of other species of birds and animals, the occasional bird is unable to clear the infection, and becomes a permanent carrier. As Dr Dorrenstein points out, it is still not known just where the paratyphoid organisms hide in the body of a carrier, but he suggests that this hiding place could be within certain patrolling defensive cells called macrophages where they are protected from the immune system. (Note: "macro"means "large"; "phage" is from the Greek word "phagein", meaning "to eat"-- hence, these are large, mobile defensive cells that engulf foreign material, such as invading bacteria, parasites, yeasts etc..) It is obvious that not all engulfed foreign invaders are killed by these large cells, but in some way, the invaders remain alive and isolated within the cells that engulfed them, and here they are protected from other defensive mechanisms in the body. As a result, during periods of stress, the immune system becomes depressed and less vigilant, as a result of which, the paratyphoid organisms can escape from their hidden locations. Once they have escaped, they begin to multiply and then to be shed in droppings from which they are readily spread to other susceptible birds in the loft.
    In my experience, variety copenhagen can be sensitive to an unusually wide variety of antibiotics, except in cases in which fanciers have misused these products and have induced antibiotic resistance in these organisms by underdosing the birds in the first place, or by treating for a shorter time than recommended, or both. For this reason, it is often practical to have laboratory tests run to determine the most suitable antibiotics to use.
    Treatment of E. coli and paratyphoid infections is best managed through laboratory assessments of antibiotic-sensitivity tests to choose the most effective antibiotic or other anti- bacterial product. Given the general misuse of anti-bacterial products, in some cases these organisms may have developed some level of resistance to antibiotics -- hence the value of laboratory cultures and antibiotic-sensitivity examinations to ensure use of the most effective product. According to Dr David Marx of Oklahoma, USA, all of his isolations of paratyphoid organisms from pigeons continue to be sensitive to Baytril (enrofloxacin), with more than 90% of these isolations also sensitive to Amoxicillin and Cephalexin.
    By contrast, Dr Paul Miller of Pennsylvania, USA, reports that his laboratory has isolated some strains of paratyphoid organisms that have developed a great deal of resistance to antibiotics, and that only Baytril seems to be effective in treating these infections. This information points up, once again, the value of laboratory cultures and an accompanying antibiotic sensitivity examination.
    In general, Salmonella species are notorious for their ability to transfer from one species of animal to another. However, in the case of variety copenhagen, it seldom ever transfers to other species, and this includes humans. So, in general, the fancier who is experiencing an outbreak of paratyphoid infection in his birds doesn't have to be overly concerned that he will contract the infection himself. However, individuals whose immune system is weakened or damaged should take extra precautions. Nevertheless, for the sake of general safety, fanciers should take normal precautions with sanitation and personal cleanliness while working with an infected flock.
    As an advocate of the use of friendly bacteria, also called probiotics, and associated products for a more natural approach in attempting to prevent E. coli and paratyphoid infections in our birds, I have noted that some commercial supply houses are offering products containing the sugar lactose to aid in preventing paratyphoid infections in particular. I certainly support the use of such products and others, in the fight against paratyphoid organisms, but I would offer a few words of caution on the use of lactose when fanciers are dealing with, or trying to prevent, problems caused by E. coli, and even paratyphoid.
    To explain in a bit more detail, friendly bacteria such as those in yogurt or in commercially available probiotics, usually include Lactobacillus spp., along with certain species of Streptococcus, sometimes called Enterococcus, etc.. In the USA, commercial products such as PrimaLac and Benebac, among others, are available. No doubt, similar products are available in other countries around the world as well. Some of these products have been developed specifically for turkeys as well as for egg-producing and broiler strains of chickens. Dr Gary Davis of North Carolina State University, USA, has done a great deal of research on the probiotic called PrimaLac in quail, pheasants, domestic ducks, turkeys and laying hens. He reports that his results have been very positive, with the most significant effects being improvements in livability, egg size, body weight gains and immunity. The poultry grade of PrimaLac is available from Bob Adams of Star Labs (Email address : bobadams@siteone.net This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .)
    Certainly, the best source of these bacteria for pigeons would be those derived from normal, healthy pigeons, if such products are commercially available. However, PrimaLac seems very promising indeed, especially because of the range of positive effects found by Dr Davis in several species of birds. It seems likely that pigeons would benefit similarly -- in fact, a colleague of Dr Davis, Dr Mike Wineland, has been using this probiotic on his own pigeons, and swears by it. The organisms in all of these products are believed to have at least two mechanisms of operation in the intestines. Firstly, they can multiply to very high numbers of organisms that form a protective physical barrier that may be up to 12 or more organisms deep, lining the inner surface of the intestines.
    Secondly, in the low levels of oxygen in which these bacteria live in the intestines, they produce and release into their environment, lactic acid which of course shifts conditions in the intestines to the acid side of neutral. (As an aside, it is my understanding that, in some countries such as the USA at least, two basic kinds of yogurt are available, one a killed product, and the other containing live cultures of bacteria. Obviously, the product containing live cultures of bacteria is the one to choose. Check the label of the product you buy. As well, remember that because these products contain live bacteria, you must not combine them with antibiotics or any disinfectant, both of which will kill the bacteria you want to use in your birds.)
    Now, E. coli and paratyphoid organisms much prefer to live and reproduce in slightly alkaline conditions, whereas in a hostile acidic environment, their numbers can drop drastically (in some studies, up to 97%). In promoting the use of such products, where practical, to reduce the heavy reliance on antibiotics to solve health problems in pigeons, I have been advocating not only the use of probiotics and a small amount of apple cider vinegar (5-10 cc per litre, or 1 - 2 teaspoons per US gallon [4 litres] of drinking water, as suggested by Dr Colin Walker of Austalia) to help acidify intestinal contents, and thereby create conditions that are hostile to the survival of E.coli and paratyphoid bacteria. While I visited Australia last year, I noted that one Sydney- based company had produced for use in pigeons, a powder containing a mix of organic acids that also would be ideal for this purpose. I am sure that other equally useful products exist also.
    As well, in dealing with paratyphoid infections, I have also suggested the addition of some lactose to the drinkers, as a source of nutrient for friendly bacteria in their production of lactic acid. Lactose is the chief sugar found in cow's milk, and is available as whey powder from health food stores, cheese and milk factories, livestock feed companies, and commercial pigeon supply houses. As noted by Dr Paul Miller, one problem with the use of lactose is that birds lack the enzyme lactase, and so are unable to break down and utilise the lactose themselves. The presence of this lactose in the intestine can draw fluids from the bloodstream into the intestine, and may result in diarrhoea and dehydration that can add to that caused by the concurrent paratyphoid infection. Fortunately, paratyphoid organisms themselves aren't able to ferment lactose either, which means that they are unable to use this sugar as a nutrient in their life processes. Equally fortunate for us is the fact that the friendly species of bacteria mentioned earlier certainly will use lactose as a nutrient in their production of lactic acid.
    Now here is the fly in the ointment, so to speak. It is important to understand that, although paratyphoid organisms are unable to ferment lactose, E. coli on the other hand are known to be lactose fermenters, that is, they actually use lactose as a nutrient in their life processes. For this reason then, it is my opinion that the use of lactose when E. coli infections are occurring should be avoided because this sugar simply aids these organisms to thrive and multiply in great numbers. For this reason, I would NOT recommend that lactose be used in drinkers when birds are affected with adenovirus + E. coli infections, or to help prevent E. coli problems. Yes, use lactose along with probiotics and organic acids,etc., to help prevent paratyphoid infections, but avoid the use of lactose when you are dealing with or trying to prevent E. coli problems.

Summary

  1. To treat ongoing E.coli and paratyphoid infections, use an appropriate antibiotic or other anti-bacterial product, preferably one selected through antibiotic-sensitivity testing by a laboratory, and at full dosage for the full recommended period of time.
  2. In an attempt to prevent these infections in future, once the original infection has been treated effectively with the appropriate antibiotic, you can add to the drinking water, probiotics such as yogurt and/or other commercially available live products, and even apple cider vinegar or other organic acids like citric acid from lemons or commercially available sources, to help create in the intestines, a physical barrier of friendly bacteria, plus acidic conditions, both of which are hostile to E. coli and paratyphoid organisms.
    It is my understanding that, in order it acquire a good, viable population of friendly bacteria in the digestive system, often takes a number of days. As a result, I usually recommend the use of probiotics for 7-10 days at a stretch, repeating at intervals, especially throughout the breeding and racing seasons. When attempting to prevent paratyphoid infections in the first place, or after infected birds have been treated with the correct antibiotic, at this time, you can add to the drinkers, lactose and apple cider vinegar, or other organic acids.
  3. The use of the sugar lactose will aid friendly bacteria in their own life processes, including the production of lactic acid, in an attempt to prevent paratyphoid infections. Although it is readily used as a nutrient by friendly bacteria, lactose is NOT fermented by paratyphoid organisms, so it doesn't aid the growth of these bacteria. For this reason, its use along with friendly bacteria in probiotics in attempting to prevent paratyphoid infections may be helpful. Lactose should NOT be given either during the course of E. coli infections, or when attempting to prevent infection by these bacteria, because of the fact that E.coli organisms actually use lactose in their life processes. There is no point in helping these bacteria to continue causing problems in our youngsters. Certainly, to try to prevent E. coli problems, use yogurt and/or other sources of friendly bacteria, as well as products such as apple cider vinegar, etc. to help acidify intestinal contents, but definitely avoid the use of lactose when E. coli are involved in a disease process.
  4. Be aware that the use of lactose in birds may itself cause some diarrhoea and dehydration.

 

 

Streptococcus bovis Infection in Pigeons      
Written by Gordon A Chalmers DVM   
Sunday, 07 January 2007
Streptococcus bovis (now called Streptococcs gallolyticus) is a bacterial organism that, in the past has been associated with the udder of cows -- hence the species name bovis, in reference to bovine, or more plainly, cattle. It is also a common, normal inhabitant of the intestines of many animals, including pigeons. In dairy cattle, it is an organism that is usually a signal or marker whose presence indicates less than optimum sanitation in the environment of the udder. By itself, this organism is usually not important as a cause of inflammation or infection in the udder of cattle (although it can cause udder infections), but it does signal to the dairy operator that sanitation around the udder of his cows is less than desirable.

In racing pigeons, however, this organism presents a totally different picture because it is becoming a threat to both old birds and youngsters in some lofts in Europe. It appears that one or more strains of this organism has adapted to cause severe disease in pigeons, and in Europe at one point, it ranked second in importance to Salmonella sp. (paratyphoid) as a cause of disease in pigeons. One of the several important features of Streptococcus bovis is its ability to mimic some of the visible changes seen in paratyphoid infections in pigeons, namely, septicaemia (meaning the presence of bacteria multiplying in the bloodstream), and one of the consequences of septicaemia, swelling of the joints when these bacteria invade the joints. As well, differentiating between infection by Streptococcus bovis and adenoviral infection is also difficult. Vomiting, which is one of the main features of adenoviral infection, has not been evident in this streptococcal infection.

In one published study, 20 cases of infection caused by Streptococcus bovis were found among 293 submissions of pigeons (mostly racing pigeons) to one laboratory in Europe. In 17 birds, the major finding was swelling and abscess-like changes in the liver (strictly speaking, birds don't produce pus, so it is not correct to call these changes "abscesses"). Swelling and abscess-like changes were also found in the kidneys of 14 birds, swelling of the spleen of 11 birds, enteritis (inflammation of the intestines) in three birds, congestion of the lungs and pneumonia in two birds, degeneration of breast muscles in one bird, white spots in the heart of one bird, air sac infection in one bird, and joint infection in one bird.

When the authors of the report on the European study had complete background histories on birds submitted for examination, they found the following information in five cases. In one case, 10-14 day-old youngsters died after 1-2 days of prostration and lack of appetite. It was found that only one of the two youngsters in a pair was affected. The liver of these birds was mottled and congested, along with congestion of the kidneys. In another case, breeders housed in a densely-stocked loft in which sanitation was poor, lost weight. New pigeons had been introduced to the loft on a regular basis. Liver and spleen of two birds examined were severely congested. Inflammation of the liver and kidneys was also found. In a third case, one bird from each of three pairs of breeders died suddenly in a period of one week, right after their eggs hatched. Their youngsters and other breeders remained healthy. These birds had been examined for Streptococcus bovis a few months earlier, and were found to be entirely negative. However, several new pigeons had been introduced to the loft in the meantime. These breeders had a septicaemia, and colonies of organisms were found distributed to many tissues. In a fourth case, one bird had chronic arthritis of the hock joint and abscess-like changes in the kidneys after it had survived an outbreak of paratyphoid, and did not respond to treatment with Baytril. (Note this point about Baytril and Streptococcus bovis! See later information.) A pure culture of Streptococcus bovis was recovered from the liver and hock joint of this bird. In the final case, a bird had died after one day's illness. Post mortem examination revealed a one-inch diameter pale, hard area in the left breast muscle. Many bacteria typical of Streptococcus bovis were found in this area.

Distilled to its essentials, Streptococcus bovis manifests its presence in pigeons in a number of ways, including invasion of the bloodstream and massive multiplication and distribution to a number of tissues and organs (liver, kidney, spleen, muscle, lung, heart, air sacs, joints), as well as infection of the intestines and production of diarrhea. Experimentally, the same researchers inoculated cultures of this organism into pigeons, firstly by intravenous injection in one group, and in a second group, by mouth. All pigeons injected intravenously became very ill and developed excess urination, beginning from the first week of this study. One young bird became lame by the 12th day, and at post mortem examination, this bird plus three others were found to be in poor body condition, and had enlargement of the liver and spleen. The affected joint contained yellow, creamy material. Five other birds also injected intravenously with Streptococcus bovis were observed for a total of 50 days after inoculation. Three of these birds passed a great deal of urine at intervals, and all of these birds had marked weight loss of 10-19%. Streptococcus bovis was not cultured from any tissue when this group of birds was examined at post mortem on day 50. In the group of six birds inoculated with Streptococcus bovis by mouth, two birds began to pass the organism in droppings by the third day, and another bird, by the fourth day. The other birds in the group did not shed this organism in their droppings. Two of the three pigeons shedding the organism in droppings were also found to have it in the throat. All birds in this group became negative on culture after one month, and none of them developed any sign of illness during the experiment.

The results of these experiments showed that the disease that occurred in inoculated birds varied considerably in its expression. As well, the course of the disease varied from very acute to chronic. The results also indicated that the disease is very difficult to diagnose without a post mortem examination and a bacterial culture of several tissues. They also showed that the signs and changes in this streptococcal disease mimic those of paratyphoid.

Another European study published in 1993 presented information on antibiotic treatment of infections caused by Streptococcus bovis in pigeons. It had been shown in earlier experiments that this organism was recovered from the intestines of 40% of healthy pigeons of all ages, and that pigeons that carry the organism in the intestines usually do not develop this disease. It was the opinion of these investigators that some unknown factor(s) might predispose pigeons to development of infections in the bloodstream, and as a result, disease. Signs of the disease include sudden death in pigeons of all ages, inability to fly, lameness, emaciation, excess urination, and green, slimy droppings.

In the usual course of events in determining the best product to use in treatment, human and veterinary diagnostic laboratories run specific tests on bacteria that are cultured from tissues of diseased humans, birds and animals, to provide guidance in the choice of antibiotic or other product to use in treatment. In this study, cultures of Streptococcus bovis were inoculated intravenously into several groups of pigeons. However, 48 hours before the intravenous injections, each group of pigeons was given a different, specific antibiotic in the drinking water, and these treatments continued through until 72 hours after the inoculation.

The results indicated that ampicillin and doxycycline prevented illness in 80% of birds tested, erythromycin in 70% of birds tested, enrofloxacin (Baytril) in 30% of birds tested, and trimethoprim in 10% of birds tested. Obviously, the two poorest drugs in these tests were Baytril and trimethoprim, so they would not likely be the first choices for treatment of this disease, although are very useful in other situations. The results of these experiments involving live birds treated with antibiotics correlated very well with the usual type of antibiotic sensitivity testing done routinely by many veterinary diagnostic laboratories. In such laboratory tests, live birds and animals are not used, but even so, agreement between the two types of tests was very good.

Overall, the authors of this study concluded that, under field conditions, ampicillin is likely the antibiotic of choice in the treatment of Streptococcus bovis, since in general, most species of Streptococcus tend to be highly sensitive to penicillin and amoxicillin (chemical relatives of ampicillin). However, Streptococcus bovis seems to have acquired high resistance to antibiotics such as the tetracyclines (eg. Aureomycin and Terramycin, for example). Most strains of this organism were highly sensitive to erythromycin, but because strains of lactobacilli living in the crop of pigeons are able to inactivate erythromycin and spiramycin, the use of erythromycin in pigeons may be limited.

A further key finding in the use of antibiotics was that the much-touted Baytril was among the poorest products in dealing with this infection. Given the widespread use - and, I suspect, overuse and misuse - of Baytril, it is reasonable that fanciers would reach for the Baytril when a streptococcal infection occurs in their birds, but information from Europe indicates that it is not the drug of choice in treating this streptococcal infection.

Because Streptococcus bovis is an organism that can be part of the normal bacterial population of the intestines of normal healthy pigeons, the factors that allow it to invade the bloodstream of pigeons are presently unknown. Some clues suggest that such invasion may be related to poor sanitation in pigeon lofts in which the disease occurs. Poor sanitation may allow for a massive buildup of potentially dangerous bacteria, viruses, etc., and exposure of pigeons to such huge numbers of organisms can overwhelm their immune systems, and allow disease to occur. Housing pigeons on wire floors may be a partial answer, because, according to this study, the lowest prevalence of this disease occurred in lofts with wire floors. (Given the various manifestations of this streptococcal infection, it is also tempting to wonder about the role of other agents, such as circovirus for example, which is known to damage the immune system of pigeons so severely that they become highly susceptible to many other infections. Whether the European investigators looked for this or other intercurrent viral agents can't be determined from a perusal of their published work.)

Although certain antibiotics seem to offer good control of the disease, at least based on current studies, treatment in the field situations may be somewhat more difficult. This is because these infections often have a good start before antibiotics are used in the first place, and poor sanitation in these lofts may interfere with treatment. During outbreaks in Europe, it was found that excretion of Streptococcus bovis from the intestines of pigeons resumed once antibiotic treatment stopped which means that these organisms continued to live in the environment, ready to cause disease again at a future time.

It is possible that on a practical level, Streptococcus bovis will prove to be a difficult bacterial organism to deal with. It seems that improved or well-maintained sanitary practices in the loft will go a long way toward prevention of infections, but even so, there is no guarantee that disease caused by this organism will not occur. Only time and investigation will identify a number of the factors that play a role, not only in the development of this disease, but in methods of control and prevention. Whether veterinary diagnostic laboratories in North America are reporting these infections in pigeons is unknown at this writing.

If sudden death or unexplained illness occurs in a loft when sanitation is not the best, or if new birds have been introduced prior to the onset of illnesses or death, it is important, regardless of the cause, to have birds examined by a veterinary practitioner, especially one who is familiar with pigeons or exotic birds. Submission of representative birds by your veterinarian to a diagnostic laboratory can help immensely in detecting infectious or other diseases, and defining the precise cause, as well as providing information on the correct treatment. This is as true for all infectious diseases as it is for the disease caused by Streptococcus bovis.

As fanciers, we need to be aware of this and other diseases of pigeons, particularly since so many such diseases can be imported along with pigeons from all areas of the world. Given the brisk world-wide trade in pigeons today, especially from the European hotbeds of racing, it seems only inevitable that this and other important diseases will land on our doorstep and of course, quite a number have arrived by these means already.

In summary, it is important to note that infections caused by Streptococcus bovis in pigeons can mimic those caused by paratyphoid organisms, possibly E. coli, and in some instances, could be confused with adenoviral infections. The key is to have affected birds examined by post mortem, and to have various organs cultured to determine the identity of the bacterial agent causing the problem. Only in this way can a cause be determined when losses such as those described earlier occur in a racing loft.
One last reminder:
Baytril is NOT the drug of choice in this disease!