Chlamydial organisms share properties of both bacteria and viruses, reproducing by division and having the ability to exist outside living cells like bacteria, but ultimately parasitizing living cells for growth and reproduction. Rickettsial organisms are somewhat of a hybrid between viruses and bacteria. They generally must live and reproduce within the cells of another organism, like a virus, yet they contain some of their own metabolic enzymes, as do bacteria.

While this may seem like more information than most people need to know, it is important to understand that these are separate life forms unique to themselves. Diseases caused by rickettsia always need a "third party" to transport the organism; they are not caught by direct contact. Chlamydia are passed by contact with infected animals.

The parasite known as Hemobartonella felis causes the only rickettsial disease of cats. The organism can be transmitted to cats by fleas (and possibly ticks), as well as from mother to unborn kittens and via blood transfusions. A few weeks after this rickettsia enters the body and begins to multiply, direct damage to the red blood cells will begin. An immune-mediated reaction can also be created causing further blood destruction. It will usually require two or more destructive bouts (in either situation) before the clinical signs of anemia will occur unless severe secondary immunologic destruction is present. Clinical signs include fever, pale gums, jaundice, lethargy, poor appetite, weight loss and death. These symptoms may come and go in irregular cycles in relation to the parasite's reproductive cycle. Diagnosis is based on history, clinical signs, blood counts and serum chemistries, which includes identification of the parasite in the blood, FeLV testing and Coomb's testing. Identification of the organism is not always possible.

Tetracycline type antibiotics usually work well if any treatment is needed. Cortisone drugs and blood transfusions might be warranted in cases where severe hemolytic anemia is also present. IV fluids are usually needed for seriously ill cats. Some cats may carry Hemobartonella so regular testing and flea control is very important in multi-cat families.

Chlamydiosis is caused by the organism Chlamydia psittaci. This organism has several strains that can attack different species including man. The feline disease commonly caused by this agent has been referred to as Pneumonitis although some experts argue that most "pneumonitis" cases are caused by herpesvirus or calicivirus infections instead. Despite this disagreement, this organism certainly contributes to cases of Feline Upper Respiratory Disease Complex and infections of the eye and nose in young cats. ((Upper Respiratory Infection))

Clinical signs generally include swelling of the eye(s) with a thick yellow discharge, increased tearing, fever, sneezing and a nasal discharge which, too, may be thick and yellow. Left untreated, pneumonia may later develop although this may be secondarily caused along with other infectious agents. Older cats can carry chlamydia and the infection can be a chronic problem in any kittens born to infected queens. Diagnosis is based on history, clinical signs and cytologic examination of exudates from the eye. There is also serologic testing now available for the disease as well. Culture is usually an unrewarding test to perform.

Most kittens respond well to oral tetracycline, erythromycin or other antibiotic therapy. Eye ointments containing these drugs also are advisable. This, plus good nutritional support and keeping the kittens clean and free from their own exudates usually produces good results. Vaccination is also available and this author recommends it be given to all cats and kittens.

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©2007 James W. Day D.V.M., P.C.