I have created this page to inform everyone about the recent outbreak of the SDA virus. It is becuase of this virus rats were not allowed to attend to the June meet.
What is SDA?
Sialodacryoadenitis is an infectious disease of rats caused by rat coronavirus (RCV). This infection of rats has been recognised for many years but the causitive agent was not discovered until 1970, when the first virus of this group was isolated. This virus was designated Parker's Rat Coronavirus (PRC) after its discoverer. A second virus, Sialodacryoadenitis virus or SDAV was discovered just two years later. These two viruses are very similar and are now considered to be strains of the same virus, namely Rat Coronavirus or RCV. Since then, several more strains have been reported, including CARS (not the same as CAR bacillus), RCV-BCMM, RCV-W and RCV-NJ. This is a virus that mutates frequently and whose virulence can vary widely, from rat to rat, strain to strain and outbreak to outbreak.
Coronaviruses are widespread among mammals and birds, (one strain is responsible for SARS in humans) but are largely species specific. RCV does not cause disease in other mammals. A related virus MHV, or mouse hepatitis virus is common in mice.
Clinical Signs
The severity of symptoms varies with the strain. Generally if the strain is new to the population then it is likely to produce more severe symptoms, as the population has no resistance to it, this is the same for most infections though.
Symptoms can vary from the subclinical (no detectable illness) to death. Most non immune rats do show some degree of illness however. Early signs, especially in very young rats, include squinting, photophobia, lacrymation (runny eyes), production of porphyrin around the eyes and nose which may also appear on the inside of the forelegs as they attempt to wash themselves. Older rats usually develop sneezing and sometimes swelling of the salivary glands at the angle of the jaw (parotid) and up the sides (submaxillary). Swelling of the Harderian and lacrymal glands around the eyes may also occur. These early symptoms develop 4-6 days post contact. However, as the first rats infected often show only mild symptoms, it may be 2 weeks or more before you realise your rats ar infected.
The eyes may then become severly inflamed, leading to keratoconjunctivitis. This is not caused by clinical infection of the eye, but by the disrupted production of tears from the infected lacrymal and Harderian glands. If this does not get better quickly then the cornea may become opaque and ulcerated. The eye itself may become greatly enlarged (megaloglobus). Dark red encrustations may be present around the eyes and nose due to the porphyrin released from the damaged Harderian glands. Other affects include weight loss, because the rat often stops eating or drinking, reduced fertility and infection of the lower respiratory tract (trachea and lungs). Like many respiratory viruses, RCV causes flattening and loss of the cilliated cells lining the passageways of the lungs etc. This leads to mucus buildup and subsequent activation of any bacterial respiratory pathogens who may be living there, including Mycoplasma and CAR bacillus. Pneumonia, accompanied by fluid build up in the lungs, is not uncommon in severe cases and is the most likely cause of death when it occurs.
On the whole, this virus is usually non fatal, although occasional outbreaks, including the latest UK one, can produce a significant number of deaths. Rats on steroids do not shed the virus for significantly longer than other rats. There is evidence that some strains of rats are more susceptible to serious illness than others.
RCV spreads rapidly among rats housed in open cages and presumably, at gatherings of rat owners and their animals. The infection rate is normally 100% of rats held in one place. Transmission appears to be primarily by droplets (sneezed out by infected rats) or by direct contact. However, RCV can survive for up to two days dried onto surfaces. Therefore, so called 'fomite' transmission (that is via cages, surfaces, clothes etc) may play a part. Intrauterine infection does not occur. Due to the rapidity of spread, most rats in a room will have had the infection and become immune within 3-5 weeks of the initial contact with the virus, even if some rats still have some symptoms left to resolve.
The virus can be killed by normal household disinfectants and temperatures of 83C. Cool washes are probably not sufficient to kill this virus.
If you get this infection in your rats, then you should avoid contact with other rats or rat owners for 6-8 weeks to be on the safe side, but it is probably impossible to prevent spread within your own rats without elaborate quarantine proceedures that are unlikely to achieve anything other than prolonging your outbreak.
There is no treatment for this infection but supportive therapy can help. This includes blanket adminstration of pain killers, such as soluble asprin or Ibruprofen in the drinking water to nursing for the worst affected. Rats who are not eating or drinking, should be dropper fed in order to improve their chances. I have found that diluted Nutrical, sweetened milk with a spot of alcohol and Polyaid can all make a big difference to a rat's chances.
Antibiotics will not touch the virus but the use of chloramphenicol eye drops does help prevent secondary eye infections. Likewise rats with the worst respiratory symptoms may be helped by a course of an antimycoplasmal antibiotic such as Baytril or Doxycycline.
This is a common virus and most outbreaks pass off without deaths or serious illness. However, when a more virulent strain does appear, it is important that committees act quickly to prevent the spread of the infection. This means stopping shows and 'gatherings' until the outbreak has subsided. However, this will not work unless individual members behave in a responsible manner and keep away from more 'informal' meetings. Likewise care must be taken when bringing in rats from unknown or dubious outside sources. These rats can often be the source of new disease strains even if they appear well. Therefore you should quarantine these rats for 2-3 weeks. Alternatively, if you do mix these rats in with your own, you will need to watch yours carefully for a few weeks. During this time, you should keep away from other rats.
Article written by Ann Storey
Other info (taken from NFRS forum)
1) rats who get eye symptoms, will get better, honestly. The odd one may lose an eye because they have scratched it however....
2) If you have kittens in the nest they should be ok, and certainly fine to breed with later, plus they will be immune. However weaners are especially at risk. Pregnant does who have not had this infection previously may also become very ill, as their immune response is impaired at this time.
3) Once you have this you don't 'keep getting it back'. Rats only carry this virus for a couple of weeks and are immune post infection.
4) The incubation phase is 4-6 days when the rat will also begin shedding virus. Most rats are improving after 14 days but they stop shedding a few days before this. Rats who are still ill after this point have a secondary infection, probably with mycoplasma, as this infection is activated by SDAV and Sendai.
5) the initial symptoms are sneezing, some never develop any other symptoms. Otherwise rats can go on to get rattles, swollen eyes and neck glands, red and crusty eyes and pneumonia. Secondary problems (not due to the virus itself) are damaged or lost eyes and activated mycoplasma respiratory disease. Death, where it occurs, is usually down to pneumonia.
6) Treatments are mostly supportive and include blanket treatment with soluble asprin in the drinking water for all affected rats to reduce fever and pain (1 tablet in 2 pints), children's Sudafed, bathing the eyes of affected rats with mild saline, abs for the worst affected to help prevent myco, fluid replacement for the worst affected. Very sick rats will need nursing care if they are to stand a chance. I have found that a spot of brandy in sweetened milk can work wonders.
7) It is strongly advised that anyone with rats that they suspect of having this condition stays away from other rats until 14 days after the last rat became ill.
the information given below is taken from the fancy-rats forum.
The symptoms of SDAV vary between rats, between strains of the virus, but they include:
SDAV is a highly contagious virus, alone it is not fatal but it weakens the immune system allowing secondary infections to take hold and often kill the rat.
The disease is spread through contact with food, bedding, cages, cage accessories, carriers, human skin, clothing and other objects used or touched by infected rats. The virus may possibly so be carried in the mucous membranes of humans which can contribute to the spread of this illness. It can survive up to 2 days away from it's host.
Rats will begin to show symptoms as early as 5 days but as late as two weeks, symptoms of secondary infections may show sooner or later depending on the infection. It it important to note that not all rats infected with SDAV will show symptoms.
There is no treatment for SDAV itself and, actually, this is not needed. However, aggressive blanket treatment with broad-spectrum antibiotics at the maximum possible doses for 3-4 weeks should be given to reduce the number of deaths in your group or rattery. Topical eye treatments are helpful to increase the rats' comfort.
Keep affected rats clean, warm and away from bright lighting. Provide extra fluid (offer Dr Squiggles or herbal teas to encourage extra fluid intake) and nutritional support
We urge everyone to employ proper quarantine as standard, but it is especially important during a virus outbreak.
When cleaning second hand cages or anything that may have come into contact with infected rats use any normal household disinfectant and for hammocks wash at temperatures of 85C or over.
If you get this infection in your rats, then avoid all contact with other rats or rat owners for 6-8 weeks after the last rat became infected. It is recommended not to try to quarantine within your own rats as this is complicated and often only prolongs the oubreak. With prompt and adequate antibiotic treatment most rats will survive this.
If anyone has an outbreak of this virus or suspects an outbreak please email us as soon as possible with details of the infection, where you and your rats have been, whether you have taken in any other rats recently and whether you or your rats have been in contact with other rats recently. This is so that we can accurately pass information between rat clubs to try and curb the outbreak. All pms will be treated in the strictest confidence, your name will not be passed on with the information.
Special thanks to everyone for letting us use this information.
Am I at risk?
No Risk: Keeping all rats at home, having feed delivered, not meeting up with any other breeder or rat owner. Not taking rats to the vet.
Very low risk: Picking up feed from pet shop, meeting ratty friend (but not the rats) who is infection free.
Low risk: Meeting friend and rats (no apparent illness). Exhibitions with one person's rats only, where these stay in their tank. Taking in rats from known source (infection free).
Medium risk: Exhibitions where rats are held, visiting the vets. Visiting friends whose rats are infected and taking full precautions on your return. Judging or visiting show with no rats.
High risk: Taking rats to shows and meets with multiple owners, rescues or homing from unknown source.
