Chlamydia
Disease is caused by a toxin that is produced by the Chlamydia organisms
Transmission :
The disease is extremely common as a carrier disease in birds and is highly contagious. Elementary bodies (infective parts of the organism) are present in the feathers, the feather dust, dried feces and aerosols of affected birds and are dispersed by air circulation. Infectious elementary bodies can survive in the environment for several weeks. Elementary bodies are inhaled and are taken into respiratory cells by phagocytosis (cell swallowing) where they later start to multiply and cause disease. The disease may occur whenever there is close and continued contact with infected birds. Birds can also transmit the disease via eggs (vertical transmission) meaning that chicks can be born with it.
Clinical Signs :
In general, acutely affected symptomatic birds present with the so-called sick bird syndrome, i.e. ruffled feathers, low body temperature and can collapse. Respiratory signs include conjunctivitis (inflammation of the membranes of the eyes), difficult breathing (dyspnoea) and inflammation of the sinuses. Birds will also present with yellow to greenish feces, dehydration and will usually die within one to two weeks.
In chronic cases the disease will present with the same signs as above plus central nervous system signs like tremors, convulsions and rhythmic eye movement. Pigeons, finches and small parakeets may develop keratoconjunctivitis (Dry EYE) with no other clinical signs.
Diagnosis can only be done properly at necropsy.
Salmonellosis (Paratyphoid)
Avian salmonellosis is caused by a group of bacteria of the genus salmonella. Approximately 2,300 different strains of salmonellae have been identified.
The paratyphoid forms constitute the great majority of salmonellae, and they are becoming increasingly important as causes of illness and death in birds.
Transmission:
Salmonella infections can be transmitted in many ways, and the importance of different modes for transmission varies with the strain of salmonellae, behavioral and feeding patterns of the bird species, and husbandry practices when human intervention becomes part of the hatching and rearing processes. Contaminated foods are the primary source for infection. Food and water become contaminated by fecal discharges from various sources. Rats, mice, and other species, including reptiles and turtles, in addition to birds, are sources of fecal discharges of paratyphoid forms of salmonellae. Inhalation of the bacterium during close confinement in high humidity environments such as hatching and brooder operations, direct contact with infected birds and animals, and insects are other demonstrated transmission routes for salmonellosis.
Clinical Signs:
These birds huddle, are unsteady, shiver, and breathe more rapidly than normal; their eyes begin to close shortly before death. They exhibit nervous signs including un-coordination, staggering, tremors, and convulsions. Blindness has also been reported in some birds. The rapid death of songbirds at feeding stations has often caused observers to believe the birds had been poisoned.
Birds often have pasted vents and eyelids that are swollen and stuck together by a fluid discharge. Commonly reported signs among all species include ruffled feathers, droopiness, diarrhea, and severe lethargy.
Candida (Yeast Infection)
Candida albicans is a yeast infection. It frequently occurs as a problem secondary to other infections, but also can develop on its own - perhaps from eating food that have been left out too long. Stress also play a role in suppressing the immune system of bird’s. .Antibiotic treatment can also wipe out the gut flora, good and bad. However, antibiotics are useless against yeast.
Clinical Signs:
Sick bird syndrome develops slowly, where the bird becomes less and less active, sleeps more, fluffs up, and loses interest in its environment. It may attack the throat respiratory tracts, reproductive organs and vent. Rattling may also occur. Candida can escalate into secondary infections.
Prevention:
Keep the environment clean, remove fresh food before it gets old. Administer a good pre-, probiotic on a regular basis.
Coccidiosis
Coccidiosis is an illness caused by a protozoan parasite that lives in the wall of the bowel. Coccidiosis is an organism that is present in low numbers at any given time and only reveals itself during low immunity or stress. It's like the "common cold". Most of us are exposed regularly to this, but only those of us who are weak or temporarily immune-impaired tend to get sick.
Clinical Signs:
Watery droppings, fluffed up, inactive birds with shaking and weight loss followed by dark green, tacky, smelly diarrhea, blood in the droppings and sudden death, are signs of Coccidiosis. Budgies, finches and pigeons are the most commonly affected species.