Exam 3 Flashcards
White-nose syndrome in bats is a ____ pathogen.
Fungal.
White-nose syndrome is currently found in…
33 states and 5 Canadian provinces, and is still spreading at an alarming rate.
Why do we care about bats?
They are pollinators and protectors of certain crops. Also, we care because we don’t want living things to die…obviously.
What causes White-nose syndrome? How does it kill?
Pseudogymnoascus destructans, or Pd destructans for short.
Pd destructans kills by causing dehydration and rapid heat loss, and increasing arousal (thus coming into contact with other bats more, spreading the disease) and causing an inability to feed. This disrupts hibernation and wing physiology.
Pd destructans is very environmentally persistant, meaning it can stay in reservoirs in the environment pretty rigorously.
How is WNS spread? Where did it come from?
It originated somewhere in France in 1918. People think it can be spread by raccoons, moths, and even mosquitos. However, it is primarily spread across the landscape by bats.
How are some ways people are mitigating the spread of WNS?
1) Biocontrol, by spreading certain bacterias that attack or inhibit Pd destructans.
2) UV light, which has been shown to weaken Pd as it is extremely sensitive to UV light.
3) Vaccines, obviously, that gives populations resistance to the disease.
What are prions?
“Proteinaceous infectious particles”.
Explain how PRPC –> PRPBSE, PRPCWD, or PRPSC.
PRP stands for “normal prion protein”. These proteins do not have a role that has been discovered yet, but the gene is not required for survival. It is usually a glycoprotein normally found at the cell surface in the plasma membrane.
When a PRPC meets a PRPBSE, it converts it to the abnormal form.
BSE, CWD, and SC are the diseases the misfolded proteins cause.
How are prions transmitted?
Firstly, a misfolded protein shows up (we dont entirely know how, as they aren’t living and they break a lot of fundamental biological principles).
This protein bumps into another and converts it to the misfolded form, which are highly resistant to most disinfectants, UV, heat, and radiation.
What is TSE?
Transmissible Spongiform Encephalitis. It affects the CNS, and can affect even humans.
It is caused by ingestion or inoculation, and is ALWAYS fatal. Slow progression.
How is TSE studied in mice?
1) 2 mice, one with PRPc and one with the gene knocked out (PRPko) were infected with PRPsc. Only the mouse with the PRPc gene were affected, meaning that without PRPc, PRPsc cannot spread.
2) Mice were expressing ovine, human, and bovine PRPc. When infected with PRPsc, only the ovine-expressing mouse was affected. We can study species barriers to transmission this way.
How do we diagnose TSE using histopathology?
Using “post mortem definitive diagnosis” - AKA, looking at the brain. It has a spongy-like appearance, vacuolated (exploded) neurons, plaques surrounded by vacuoles.
How do we diagnose TSE using immunochemistry?
Using antibodies specific for the prion protein antigens, which bind to it and stain it a certain color in tissue sections.
What is scrapie? What are the clinical signs?
A prion disease in sheep. It causes weight loss with a ravenous appetite, behavioral changes, excessive itching, rubbing, wool pulling and lip smacking and changes in gait.
Is there a genetic predisposition to scrapie?
Yes, it seems that the several variants of the PRNP gene can affect susceptibility or resistance to scrapie, and can also affect how long the disease incubates for.
What is BSE?
Bovine spongiform encephalitis. Depending on the dose ingested, the incubation period can be anywhere from 2-8 years.
The average age of onset tends to be 5 years.
Clinical signs include excitability, nervousness and aggression, sensitivity to noise, slow movement, and tremors.
What was the timeline of BSE outbreaks in europe, US and Canada?
1986, the first case confrmed.
1988, UK banned meat and bone meal from cattle feed.
1989, USDA bans importation of meat from countries with BSE.
1997, US & Canada ban ruminant products fed back to ruminants.
2001, EU ordered mandatory tests on cattle destined for slaughter.
2003, BSE found in washington state.
As of 2018, 6 cases of BSE in US. All have been sporadic and atypical.
What is Kuru?
Identified in New Guinea in 1900s, it was found in a tribe practicing cannibalism.
Women, children, and eldery infected 5x as often as men. The incubation period is also over 30 years.
What is CJD?
Creutzfeldt-Jakob disease. Age of onset usually 65 uears and kills in 4.5 months. It tends to be sporadic, but can also be inherited.
What is variant CJD?
CJD from consuming BSE contaminated foods, with the first case appearing in the UK in 1995.
Little is known, incubation period not known, nor is dose required. 28 years average age of onset, with duration being 13 months.
Possible genetic component, as all human cases have been homozygous at codon 129 of PRPC.
Initial symptoms are depression and schizophrenia-like psychosis, unsteady movements, progressively immobile and mute. No treatment available.
What is CWD?
A prion that affects deer, found in NA, Norway, and South Korea. Orginal epicenter in northeasternish Colorado.
Affects deer, no cases of human transmission YET. Does not YET appear to infect cattle.
Incubation is 12-64 months, but varies. Ingestion of prion from dirt or grass or contact with bodily fluids believed to transmit. Also believed to remain in the environment for long periods.
Causes weight loss, lack of coordination, drooping ears, and hypersalivation.
What are the differences in CWD infections in free vs captive populations?
Free rangings had slow proliferation, stable prevalence, and slow rates of diffusion, with a 10-15% infection rate.
Captive hers had faster dispersion, with an up to 79% infection rate. They can
What are some other examples of TSE?
Mink encephalopathy in MI and WI in 1947.
Feline encephalopathy, exclusively in the UK.
Exotic ungulate encephalopathy, exclusively in UK.
What are some ways to prevent TSE?
1) the FDA “animal feed rule” which bans using mammalian proteins as a source of food for ruminants.
2) 1989 import restriction on countries with BSE.
3) BSE testing of all rendered animals.
4) Surveilance, CWD testing, Scrapie National Eradication Program
What are some current issues with TSE?
Theres no reliable antemorten test.
Its difficult to study due to long incubation times.
Its very difficult to control spread in wildlife and environment.
Its risk to humans is unclear, but has huge and widespread economic impacts.
What makes the ecology of WTD so special?
Subspecies that occupy many varied niches and habitats and the fact that they are highly adaptable.
They are edge species.
Local food supplies are fundamental to pop dynamics: forested areas w/ lots of forage species means higher densities of deer. High pops can degrade communities and destroy the habitat for other wildlife species.
What are characteristics of captive deer populations?
They are often bred for specific traits, lke large racks, meaning herds may have genetically similar animals.
They have very high stocking densities and can also still interact with free-ranging populations.
Infected with CWD at higher rates and can also spread to wild populations.
What are difficulties of controlling CWD?
Eradication once it has been established in an area is actually impossible with the current tools available.
What is bovine tuberculosis and how does it infect deer?
A respiratory infection caused by M. bovis and M. tuberculosis. Spread primarily through exchange of repiratory secretions, and can remain in the environment for weeks to months.
It is a chronic and progressive disease that causes absesses, nasal discharge, and swollen lymph nodes.
It is diagnosed with cultures, as necropsy findings are not always present. No effective vaccines or treatment available.
How is bovine TB controlled in domestic animals?
1) carcass inspections at slaughter.
2) Live animal testings
3) TB being eradicated when found in herds.
How is Bovine TB controlled in deer?
Deer can spread to uninfected cattle, so limiting shared feeding & direct contact helps.
Reducing deer density in designated TB management zones.
Elliminating baiting of deer.
Continual monitoring of bovine TB by testing hunter-harvested deer
What is Hemorrhagic disease?
An orbiviral disease of ruminants.
Transmitted by Culicoides spp. midges. Includes BTV and EHDV.
Causes infections, chronic lameness, and wasting in cervids.
They are expanding northwards and increasing in frequency.
How do orbiviruses affect domestic animals?
They cause fever and depression, nose discharge, redness and swelling of muzzle, swelling of tongue, and abortion.
Causes economic losses, such as damaged wool and decreased milk production.
What are some current issues with WTD?
1) they have suburban and urban populations that are virtually uncontrolled without human intervention.
2) current management is controversial.
3) captive deer farms are also controversial and pose regulatory difficulties.
4) deer pop can be DRAMATICALLY affected by several infectious diseases.
5) deer can be subclinically infected by other species, but spread the agents to other species.
What is happening to herpetiles?
Ectotherms are more vulnerable to certain types of diseases, and they are emerging at an alarming rate for unclear reasons.
Some of the largest disease related population declines ever have been in herps.
What is snake fungal disease?
A skin infection caused by the fungi known as O. ophiodiicola.
The majority of cases are mild, but can vary in severity. Can also be referred to as “hibernation sores”.
Only poses a threat to a few pops, and may be a native pathogen. Climate change may play a role here.
What is ranavirus?
Discovered in the 1960s, in the 1990s became a major pathogen of amphibians that causes massive population die-offs in the larvae.
The origin is unknown and may be spreading due to deteriorating environmental conditions.
Has been found in turtles in NA recently.
What is Chytrid fungus?
Caused by the fungus B. dendrobatidis and was found in the 1990s in australia, but conflicting theories of the origin.
Now has a global distribution due to humans spreading the disease.
It causes skin infections and persists for a long time in the environment. Has caused a believed 30 extinctions in species in Panama alone.
