Family Asfarviridae Flashcards
virus in this family?
only known???
host
african swine fever
only known DNA ARBOVIRUS
-all breeds of pigs, inapparent infection in warthogs and wild hogs which are reservoirs
african swine fever — notifiable??
OIE LIST A DISEASE = notifiable!!
african swine fever
-distribution endemic vs. recent outbreaks
endemic: africa and italy
recently: in eastern europe and russia
ASF stability
virus survives at least 30 days in pens, very resistant to wide pH, survive in chilled carcass, resistant to putrefaction, remains viable for long periods in blood, feces, and tissues: in uncooked or undercooked pork products, can multiply in vectors (soft tick)
ASF hemadsorption
virus does not hemaggultinate, pig erythryocytes will adhere to the surface of pig monocyte or macrophage cells infected with ASF virus.
-hemadsorption (HAD) is attributed to virus specific protein that appears on plasma membrane of infected cells during late infection
ASF transmission
VECTOR: soft ticks! - ornithodoros
-biological vectors of the virus, virus replicates in tick, resulting in trans-stadial, transovarial and sexual transmission, infected ticks may live for several years and capable of transmitting virus to pigs duirng each blood meal
ASF
-reservoir hosts (sylvatic cycle)
warthog, giant forest hog, bush pig = virus maintained
ASF
- transmission
persistent infection of ticks, tick to tick trarnsmission: transstadial, transovarial, sexual
-adult warthogs: no viremia, virus in various lymphoid tissues
-juvenile warthogs: significant viremia = source of virus for ticks!!!
-ticks connect sylvatic (tick and warthog) and domestic cycles
-transmission among domestic cycle: direct contact secretions
-primary outbreaks in domestic swine from: bite of infected tick, direct contact with infected animal, indirect contact on fomites, virus spreads to new areas when pigs are fed uncooked scraps that have infected pork, aerosol spread, mechnical transmission through biting flies
-ALL BODY FLUIDS AND TISSUES contain large amounts of infectious viruse
-pigs that survive infection may become carriers and shed viru sin secretions and excretiosn
ASF
-pathogen.
hemorrhages and apoptosis
APOPTOSIS: p54 protein encoded by virus directly incudes apoptosis of host cells, ASF infected macrophages release cytoK and apoptotic mediators, apoptosis of both mononuclear and lymphocytes
HEMORRHAGE: vascular damage from degen. of vascular endothelium, DIC, infection and necrosis of megakaryocytes, activate and destruction of monocytes and macrophages, thrymobytopenia and coagulation defects lead to : edema, infarction, exudation and hemorrhages in organs and tissues
-leukopenia, lymphopenia and thrombocytopenia
ASF
CS - peracute, acute and chronic
-peracute: may die suddenly
-acute: high fever, CYANOTIC SKIN BLOTCHING on ears, tail, lower legs and hams, respiratory distress, diarrhea: initially mucoid and later bloody, abortion: sometimes first event seen in an outbreak, death
-chronic: emaciation and stunting, swollen joints, ulcers and reddened or raised necrotic skin foci, pneumonia
-NECROPSY: enlarge friable spleen “BLACKBERRY JAM SPLEEN” in the acute form - spleen enlarged and congested
-chronic ASF: cutaneous lesion and fibrinous pericarditis and myocardial hemorrhage
ASF immunity
-infected pigs produce virus specific AB, sera from infected pigs do not neutralize virus, hence humoral immune response does not seem to have substantial protective value, attempts to develop a vax have so far been UNSUCCESSFUL
ASF prevention
and what to do during an outbreak
-pig farmers and personnel should be aware of it and be able to recognize and know what to do if they suspect
-pigs should be in well constructed pig sties under hygienic conditions with controlled entry to the piggery
-movement of pigs inside the country and across international borders should be controlled
-pigs should not be fed swill that might contain remains of pigs, ensure safety - swill shoudl be boiled for 30 min and cooled before feeding
DURING AN OUTBREAK
-IMMEDIATELY NOTIFY AUTHORITIES (animal health dept.)
-infected and suspected pigs in quarantine
-no movement of pigs or any products of pig origin allowed
-all infected and in contact pigs must be slaughtered
-carcasses must be burnt or buried deeply on site
-vehicles should be disinfected on entering and leaving farms
-personnel should ensure that shoes, clothing and equipment are disinfected between farms
