RCReptiles.com

[deborahbroadus]

Having recently experienced a large decimation of my rat population, I learned that (duh, I forgot all my biology lessons) some rats may be resistant to germs that other rats have.

A disease that can wipe out large populations of rats is: Sialodacryoadenitis
http://hometown.aol.com/RattLvrr/SDA.htm
SDA

Sialodacryoadenitis Virus
What is it?

Rats are the natural hosts for this extremely contagious coronavirus. It is related to the mouse hepatitis virus (MVH), but isn't the same thing. This is a disease that infects only rats. It is a respiratory disease that affects the lacrimal glands, (tear ducts) the salivary glands, and the Harderian glands that are behind the eyes. Unfortunately there exists more than one strain of this virus, some strains are more deadly than others are.

How is it transmitted?

Direct contact from rat to rat, respiratory aerosol. It can also live on objects and surfaces for a short amount of time so touching infected objects may spread the disease. You may spread this virus to your rats if you handle others and then not wash your hands.

Signs and Symptoms

Clinical signs may be seen in a colony for weeks, but individual rats may exhibit symptoms for only about one week. These signs may be: sneezing caused by acute rhinitis, squinting, blinking, desire to get away from bright lights, eye rubbing followed by cervical swelling (the neck area). Swelling is caused by inflammation of the salivary glands and enlarged lymph nodes. Eye moisturizers are often needed to keep the eyes from drying. If they eyes are allowed to become too dry the rats may lose their eyes. Drying eyes are irritating and the rats may rub and scratch at their eyes making things worse. With the pneumonia type strains of this disease when combined with Mycoplasma infections Sendai virus or other infections, death is more likely to occur.

Treatment

There is no treatment other than antibiotics to ward off secondary bacterial infections, medications for the eyes to prevent eye loss, and fluids to ensure the rats don't become dehydrated. Things you can do at home that may help: run humidifiers if the house is too dry, keep an open jar of Vick's Vapo-Rub on the cage in a spot where the rats can't reach it and then cover the cage and jar both. This may help with the rhinitis. There is a farm animal product called Vet RX that basically does the same thing the Vick's will do. You can use that instead if you prefer.

The good news about this particular virus is that rats will carry the disease and shed it for about seven days. They may take up to two months for full recovery but they do not carry this virus for life. Once it has run it's course it is gone and they have a long-term immunity to it. During an outbreak quarantine is vital, no breeding or bringing in new rats for two months is a necessary practice.

The bad news is that although they have a long-term immunity to the strain that they recovered from, they are not immune to other strains of the virus. It is possible for a recovered rat to become infected again if exposed to a different strain.

Written by Jan McArthur, R.V.T.
References:
The Biology and Medicine of Rabbits and Rodents: By John E. Harkness and Joseph E. Wagner
Infectious Diseases of Mice and Rats: from The National Research Council

Another source: http://www.ratz.co.uk/quarantine.html