Emerging vector borne diseases Flashcards
Give 3 EGs of Tick-borne VBDs
1) Lyme
2) Tick-borne rickettsias
3) African swine fever
Give 2 EGs of mosquito-borne VBDs
1) Heartworm
2) west nile
EG of sandfly borne VBD
Canine leishmania
3 EGs of midge-borne VBDs
1) Bluetounge
2) Africa horse sickness
3) Schmallenberg
Define an emerging disease
- a disease that has newly appeared in a population, or that existed previously but is rapidly increasing in incidence or geographic range
Define a vector-borne disease 3
1) A disease caused by a pathogen spread by an arthropod host
2) Not a disease with an intermediate host (eg snail)
3) Not a disease caused by the arthopod itself
Where, when and how many horses did the two african horse sickness epidemics cause?
1) western cape, 1854-55, killed 40% of entire horse population
2) middle east,1959-60,killed 300,000 equids
when, where and how many pigs did the two outbreaks of african swine fever cause?
1) cuba, 1971, 400 000 pigs diesd or slaughtered
2) cameroon, 1982, 80% of all swine destroyed
When, where and how many sheep di the two epidemics of bluetongue cause?
1) southern europe 1998-05, 1 mil
2) Northern europe, 2007, 200,000 cases on 60,000 farms
Rift valley fever -where, when how much $ lost?
Somalia, 1998-2002, export loss about $435 mil
screworm- libya, 1989-1991, eradication costs
libya, 1989-1991 about 66 mil
hard tick families
Ixodes, Rhipicephalus
Soft ticks
Argasidae
Describe Lyme disease
- borreliosis
- spirochaete, borrilia burgdorferi, spread by ixodes ricinus “sheep/deer tick”
- disease of people, large animals, dogs
- important emerging human disease causes: rash, flu,fatigue,joint pain,neuroborreliosis
- not of major importance in dogs but can cause fever, lameness, joint pain, swollen lymph nodes, lethagy and inappetance
- in UK >1000 confirmed human cases pey year
- prevalence of borrelia-infected ticks on UK dogs:481 per 100,000 dogs (0.5%)
Whatare the drivers of lyme disease emergence
-Spread of ticks to higher altitudes and latitudes (likely related to climate and landscape change (more deer?))
What is the most common vector for babesiosis, ehrlichiosis and anaplasmosis?
Ixodes ricinus (sheep/deer tick)
what does Dermacentor reticulatus spread
Ornate cow tick- now present in southern england
what does Rhipicephalus snaguineus (brown dog tick) spread?
-babesia, ehrlichiosis anaplasmosis and rickettsia rickettsii
incersions into the UK infests some houses
what is mediterranean spotted fever, spread by?
Rickettsia conorii spread by Rh. sanguineus, little clinical importance but high prevalence
What is a driver of the emergence of hard tick borne diseases?
1) spread of ticks- probably related to climate
2) increased movement of animals( eg dogs)
3) changes in international regulations - dont have to treat dogs to cross border
whats special about african swine fever
only dsDNA virus known in the group arboviridiae
Describe african swine fever
- Causes fatal haemorrhagic disease of pigs; infects boar and warthogs
- spreads by aerosol, the bites of ornithodorus soft ticks or in feed
- highly stable virus: survives 15 weeks in chilled meats; 6-9 months in cured meats; 15 years in frozen meats
- no vaccine. outbreaks dealt with by culling and stamping out.
describe african swine fever emergence
- Endemic in africa
- endemic in boar in sardinia with spill-over into domestic kids
- spread to eastern europe
- western europe at high risk
Name a zoonotic disease transmitted by mosies and discribe
Heartworm, severe and potentially fatal for dogs and cats,Dirofilaria immitis and D. repens transmitted by mosquitoes, originated in USA but now global, including europe, usually sub-clinical or chronic infection for years., can infect humans
Describe aedes albopictus
- asian tiger mosquito
- day-biting
- eggs laid in water can survive desiccation
- transported around world in used types and ‘lucky bamboo’
- vector of dengue, chikungunya, dirofilaria (heartworm)
- responsible for large apidemic of chikungunya in indian ocean islands and india
describe aedes spread from southern europe
- appears to have spread up the main motorway into france and germany
- in netherlands but restricted to neherlands
what are the vectors of canine heartworm
about 70 species of Culicidae including culex pipiens aedes vexan aedes albopictus
Describe West nile virus
+ssRNA, Flavivirus, Flaviviridae (dengue, YF, JEV,TBEV)
2 lineages
Transmitted by culex mosquitoes
Birds are natural hosts
causes severe disease and death in horses
causes fatal neurological disease in humans
West nile- history
First isolated in 1937 from west nile region of Uganda
Identified in birds in Egypt 1953
Israli strain entered the USA
which rapidly spread across the USA, killing birds, horses and people
Name drivers of WNV in USA and europe
USA-competent vectors, naïve hosts
Europe- CLimate change?
Vector of WNV
Culex pipiens pipiens
Culex pipiens molestus
describe canine leishmaniasis
In Europe caused predominantly by kinetoplastid parasite leishmania infantum (rarely major, tropica)
transmitted by phlebotomus sandflies
latin for biting midges
Culicoides
What are the problems with biting midges
-Economic damage limit tourism and outdoor activity severe allergic dermatitis in horses -transmission of pathogens 53 viruses 12 spp of protozoa 18 spp of fil nematodes
what are the two viruses in orbivirus: reoviridae
Bluetongue and African horse sickness
Describe bluetongue
25 serotypes
causes severe disease in sheep mild in cattle
first discovered in 1904 spread acros asia Americas Australia europe
describe African horse sickness virus
9 serotypes
causes severe disease in horses, mild in mules/ donkeys
first discovered in the 18th century in south africa
Describe schmallenberg virus
- clinical disease (milk drop in dairy cattle) first detected in late summer 2011 in Germany
- crosses placenta and causes birth defects
- transmitted by culicoides biting midges
- spread incredibly fast across europe
What are the drivers of bluetongue and schmallenberg viruss
- Climate change, causing midges to spread, increasing there vector competence
- global movements of animals/goods- bring viruses to Europe
- virus evolution SBV is novel
