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What is Horizontal transmission?
oTransmission of diseases within the same generation, by direct contact means
What is Vertical transmission?
oTransmission of diseases from one generation to the next by the mother to the offspring
Epizootic means?
oA sudden disease outbreak that affects a large number of animals (similar to an epidemic in humans)
oIf it commonly occurs in several members of a population or colony, it’s an enzootic (endemic in humans)
oRefers to sick animals
oNumber of sick animals at a particular location divided by the total number of animals in that location – expressed as a percentage

 100 mice in a room, and 15 of them are sick (15/100) – the morbidity rate is 15%
oRefers to the number of animals that die from a diseases
oNumber of animals at a particular location that die from a disease divided by the total number of animals at that location – expressed as a percentage
oSick animals that are near death

•Mouse Hepatitis Virus (MHV)
oMost often associated with the GI tract oCan cause severe diarrhea and death in infant mice oHighly contagious   oOne of the most significant of the mouse viruses in terms of potential effects on research data •Even subclinical cases cause severe suppression of the immune system by decreasing the production of lymphocytes, decreasing the phagocytic action of immune cells, and decreasing the production of some cell substances that act to fight infections   oTo eliminate from the colony: •It is best to use caesarian or embryo transfer rederivation of valuable lines\strains •Can halt all breeding for 6-8 weeks oAcute phase of the diseases and complete elimination of the virus occurs in approx. 2 weeks. •If no new susceptible pups are born, the virus will be gone from the current population and pups born after that time will not be exposed to the virus

•Mouse Parvovirus (MPV)
oDisease of the GI tract oUnlike MHV, it is always subclinical oLike MHV, it causes alterations of the normal immune functions oMore difficult to eliminate because the virus can survive for much longer in the environment and Parvoviruses are resistant to chemical disinfectants oNot easily eliminated by cessation of breeding, therefore, rederivation is the preferred method

•Epizootic Diarrhea of Infant Mice (EDIM)
oDisease of the GI tract oCauses watery, yellow stools in mouse pups during the first 2 weeks of life oWaste accumulations around the anus\base of the tail are characteristic clinical signs of EDIM oInfected adults show no clinical signs oCan affect research due to increased mortality, reduced weight gain, and greater susceptibility to other infections oRederivation is the preferred method of eliminating the virus from the colony
Mousepox (Extromelia)
oCaused by the Ectromelia virus   oImportant because it results in high morbidity and high mortality   oDepending on the mouse genotype, the virus can produce severe disease with acute hepatitis and high mortality   oIn animals that survive long enough, this virus produces a  generalized rash   oTransmitted through imported mice and biological materials (tissues, cell cultures)   oClinical signs may vary from none to unthriftiness, hunched posture, rough haircoat, facial swelling, and necrosis of appendages with eventual sloughing, and sporadic deaths   oSkin lesions may resemble fight wounds   oNo treatment

•Sendai Virus (SEN)
oInfects lab rats and other species, but it is most clinically significant in mice.   oIn young adults it is unapparent, but in the very young (neonate\weanling) and the very old, it can produce an acute, fatal respiratory disease.   oHighly infectious and disseminates rapidly   oMorbidity is close to 100%   oSuppresses the immune system, causing affected animals to develop secondary bacterial infections   oDisease is exacerbated by stress   oClinical signs include: •Unthriftiness •Rough haircoat •Hunched posture •Dyspnea •Chattering\respiratory sounds (rales) •Decrease in litter size\stunted pups in a breeding colony •Elimination requires rederivation or cessation of breeding – similar to elimination of MHV

•Lymphocytic Choriomeningitis (LCMV)
oFound naturally in mice and hamsters   oZoonotic!   oGuinea Pigs and other species are occasionally infected with this virus, only mice and hamsters are known to actually transmit it   oNot naturally prevalent in modern lab animal facilities, but, some investigators may use LCMV as part of their experimental protocol when studying vaccines   oInfection in a colony can also be introduced through tissue cultures, transplantable tumors, and feral animal carriers
Sialodacryoadenitis Virus (SDAV)
oCoronavirus that is antigenically similar to rat coronavirus and MHV   oMay or may not be clinically apparent   oSome rats may be active and eating well, but closer examination reveals swelling in the neck region   oSalivary gland involvement so infected rats often reduce their feed intake   oMicroscopically, changes in the Harderian Glands and Salivary Glands can be dramatic   oSome infected animals develop ophthalmic lesions, which result in cloudy corneas and reddish discharge •Lesions consist of keratoconjunctivitis and corneal ulcers – with proper treatment, they resolve in about 10 weeks but eyeball enlargement (megaloglobus) may still persist •Highly contagious and often widespread in research and production rat colonies
oMycoplasma pulmonis produces chronic respiratory disease (CRD) or murine respiratory mycoplasmosis (MRM)   oMRM has been, and in some colonies still is a major health problem of lab rats   oMay begin as an inner or middle ear infection which may result in a severe head tilt   oPulmonary involvement is seen later in the course of this disease even though M. pulmonis is primarily a pathogen of the respiratory tract   oStress can cause increased mortality   oOn necropsy, gross observations reveal areas of red to gray consolidation of the lungs, often with abscesses   oOnce established it becomes endemic in a colony and cannot be easily eradicated
oUncommon in laboratories with sufficient environmental controls\monitoring   oCaused by insufficient environmental humidity (<20-30%)   oIncreased temperatures and drafts predispose rats to this condition   oOther physiological factors  involved (age, nutritional status..etc.)   oCircular constrictions of the tail – necrotic tissue may slough   oDiagnosis is made via clinical signs and a history of low environmental humidity
oCommon in rodent colonies especially transgenic mice
oMites are the most common in rodent colonies   oLice are occasional   oClinical signs include •Pruritus •Hair loss\thinning •Skin lesions   oTreated used anti-parasitic drugs (ivermectin\pyrethrin)
oCommon in rodent colonies   oNo clinical signs, but alterations in immune responses have been seen   oRectal prolapse occurs in young mice with a heavy parasite load   oDetected by performing a fecal examination or by use of the cellophane tape test   oEasily transmitted on contaminated clothing and hands!   oOnce spread, they are difficult to eradicate because the ova are highly resistant to chemical, heat\dry destruction   oEffective treatment involves careful attention to cleaning and administration of drugs (piperazine\ivermectin\fenbendazole)
Bacterial Pneumonia
oCommon cause of death in guinea pigs   oAssociated with Bordetella bronchiseptica and Streptococcus pneumoniae   oMay go unnoticed until precipitated by stress oMost clinical signs are nonspecific •Anorexia •Rough haircoat •Occasional dyspnea •Nasal discharge •Torticollis   oAcute deaths may occur oRabbits may be a carrier of B. bronchiseptica, so it is strongly recommended that these species are not housed in the same areas   oTreatment with an antibiotic can be successful

•Scurvy (Hypovitaminosis C)
oVitamin C deficiency   oAffected animals lose their appetite and are reluctant to move   oIf they are picked up\handled, they will cry out   oOther clinical signs include: •Diarrhea •Weakness •Stiffness •Petechia of the mucous membranes •Delayed wound healing •Teeth grinding •Still births   oNecropsy shows hemorrhages in the muscle tissue\joints   oImproper storage of feed can cause a breakdown in the vitamin that is normally in commercially available diets for these animals o oMust pay attention to milling dates Unstabilized vs. stabilized Vitamin C in diet
oCaused by the bacteria Pasteurella multocida   oCommonly occurs in rabbits and is difficult to treat because the organism may localize in numerous organs   oSome rabbits are asymptomatic carriers   oMay spread via aerosol transmission or direct contact   oStress may cause reappearance of signs of the disease   oClinical signs include: •Mucopurulent (pus) nasal and ocular discharge •Sneezing •Exudate (drainage) on the forelegs •Head tilt (associated with an ear infection) •Localized abscesses •Genital infections   oCan progress into pneumonia   oUsually sensitive to antibiotics, but they do not offer a complete cure – remission is usually temporary   oVendors to have Pasteurella-free rabbits

•Mucoid Enteropathy
oNot well understood •Diet, intestinal flora, and the shift from neonatal to adolescent digestive physiology are thought to contribute to development of the disease.  •Diets low in fiber (<10%) result in a higher incidence of ME.  •No single bacterium has been implicated as a causative agent; however there are increased numbers of coliforms, and a toxin-like secretagogue believed to be involved in the disease   oSeen in 3-10 week old rabbits that have recently been stressed   oClinical signs include: •Mucus in the drop pan •Abdominal distention •Dehydration •Wet\stained perianal fur •Tooth grinding •Sloshing sound when abdomen is palpated   oReducing stress, good sanitization, and an increase in dietary fiber seem to be sufficient for prevention   oTreatment is symptomatic and is typically unsuccessful after signs have developed

•Gastric Trichobezoars
oHairballs oAssociated with over grooming which may be a result of boredom oShould be suspected when the animal stops eating\drinking and when little or no fecal material is found in drop pans oTreatments include the administration of mineral oil, a laxative, and increased roughage oBest prevented by providing large amounts of dietary fiber

oCommon in conventionally-housed rabbits oUsually affects the intestines oHepatic infections may be seen but they are caused by a strain that is different than the intestinal disease   oClinical signs include: •Weight loss •Sticky feces •Profuse, watery, sometimes blood diarrhea •Potbellied appearance in the hepatic form   oNo effective treatment, although sulfa drugs may help eliminate signs of the disease   oPreventive measures include good husbandry, the use of suspended cages with mesh flooring, and culling of carrier animals

oCaused by Mycobacterium tuberculosis or M. bovis oOld world primates are highly susceptible oRare in the wild •Usually contracted from humans   oSlowly progressive with as much as a year between the time of infection and death   oPublic health significance (zoonotic) so early diagnosis is important   oMonitor animals\staff with intradermal tuberculin testing   oRadiographs in primates are not useful for diagnosis unless the disease is very advanced •In humans, there is calcium deposition in the lesions   oClinical signs are not apparent until it has reached advanced stages •Weight loss, general unthriftiness, diarrhea, respiratory infection, and skin ulcerations

oViral disease   oUsually occurs after contact with infected humans   oFacility personnel who have been exposed to anyone with measles must notify their supervisors so they can be put in a different area for work   oClinical signs: •Rash •Nasal and ocular discharge •Conjunctivitis •Facial edema •Blepharitis (eyelid swelling) •Occasional respiratory signs   oUsually a mild disease and just requires supportive care

•Herpes B Virus
oOld world monkeys of the genus Macaca are carriers of this virus   oNow known as Cercopithecine Herpesvirus I   oFrequently asymptomatic in rhesus, cynomolgus, and others of this genus   oOral lesions\ulcers are the most common sign of a Herpes B infection   oZoonotic, can be fatal to humans   oInfection usually occurs through bites\scratches and contact with bodily fluids (blood, urine) that is splashed into the eyes

hypovitaminosis C
Bleeding Gums

•Vitamin D3 deficiency
oMetabolic bone disease •Deformities\fractures

  oRickettsial disease caused by Coxiella burnetii   oMost commonly associated with sheep   oPassed in bodily fluids such as milk, amniotic fluid, and through placental membranes   oTransmitted by ticks and aerosols of dust from infected pastures   oZoonotic   oIt is either unapparent or produces only mild symptoms that are easily mistaken for influenza   oDeaths from bacterial endocarditis can occur although it is infrequent   oSpecial precautions for disease prevention are not necessary as long as only male animals are used un flocks maintained on pasture or in open-air facilities   oDiagnosed by serology for both the animals and humans •Personnel may need to have blood samples to be taken to identify exposure  
Contagious Ecthyma (Orf)
oCaused by a pox virus   oAffects sheep and goats primarily   oZoonotic   oEndemic in most sheep herds so gloves should always  be worn when handling these animals   oCauses pox-like blisters on the lips, nose, and sometimes feet   oSelf-limiting disease – goes away on its own   oIn humans, transmission usually occurs through an open wound •A painful blister (similar to chicken pox) forms at the sit of entry
Red leg
oBacterial disease caused by Aeromonas hydrophila   oOccurs after an environmental disturbance like sudden temperature changes, an increase in population density, a dietary change, or stress due to shipment   oClinical signs include: •Lack of movement •Cutaneous hemorrhages •Erosion of the toes\feet\jaws   oAntibiotics such as enrofloxacin are used to treat this
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