First human case in china in 2002 First arose in meat markets which held contaminated animals (palm civets, raccoon dogs, hog badgers – the amplifying hosts) Traced the virus back to the Chinese Horseshoe Bat ( Rhinolophidae ) Symptoms of SARS are fever, dry non-productive cough, shortness of breath, death from respiratory failure in 3-10% of cases (caused world-wide hysteria)
Chinese horseshoe bat host lives in a cave dwelling community with large numbers of individuals – this provides the perfect environment for spread of virus (reference the many bats on the slide when speaking about this!!) 2002 – first cases in wildlife meat markets in China
LYSSAVIRUS AND RABIES -Bats are the only mammals in Australia to carry Lyssavirus. EFFECTS OF VIRUS Bats may be persistently affected, but may not show any pathological signs. -Almost 100% mortality in humans if not treated before symptoms develop.
TRANSMISSION In the US: humans acquiring rabies from bat-associated variants most common. However, the average is 1-2 cases per year showing the rarity of these events. ECOLOGICAL FACTORS Misconceptions about bats: many see bats simply as hemotophagous hosts (even though only a few species are blood eating). Bad reputation throughout society. Need for more education and awareness throughout society about bats, rabies, and prevention. (Extra Info: In case of questions) DEFRA Pet Travel Scheme and Rabies: Rabies vaccination 6 months prior to entering UK Rabies Titre Test No need for quarantine due to this new protocol, however, the process is still stringent.
-effect on the host bat is minimal, but may cause abortions-- one way the virus spreads to horses/pigs -effect on horses/pigs very virulent/fatal Effect on primary hosts is minimal, but in the secondary hosts it is known to cause encephalitis and acute respiratory illnesses (horses, pigs)
-virus caused abortions in bats- possible means of transmission Bat migration follows seasonal patterns of fruits they eat- local fruit trees match season of infections for both outbreaks Transmission to different areas also occurs because they forage and then defecate in different locations Australian outbreak was Hendra- few human deaths
Marine birds, especially gulls may act as a vector and resevoir of pathogens.
PCBs (polychlorinated biphenyl) are synthetic oil-like chemicals used for insulation in electrical equipment PCBs are soluble in fat, therefore easily absorbed into blubber DDT (dichlorodiphenyltrichloroethane) are a type of insecticide used during WWII to prevent malaria in Europe, PCBs and DDT in run offs to ocean PCBs and DDT reduce immune response and affect all main organs (spleen, liver, brain) Less fish = poor nutrition, their not at their best
In one specific species found in the British Isles, lungworm Pseudalius inflexus is thought to be a vector. Prevalence of Brucellosis in humans is greatly underestimated in developing countries.
The relationships between emerging infectious diseases of humans, domestic animals, and wildlife are complex and the roles these animals play in the transmission of several diseases is an important aspect to be considered by future veterinarians like ourselves. The behaviors and migration patterns of both the diseases and their vectors of transmission is an area of research that is largely understudied. A further understanding of the nature of migratory behavior as well as the emerging diseases will be essential in the prediction and prevention of zoonotic outbreaks in the future.
Transcript of "SDLA"
Emerging InfectiousDiseases in Wildlife SDLA Group 4 4 Feb 2010
The Problem Newly emerging diseases Gain notoriety after human infection Cross-species transmission Animal vectors – Birds – Bats – Marine Mammals
Bird Migration Bird migration as a mechanism for disease spread Birds on the move – >300 species native to North America move to Central, South America, and the West Indies – Along the seaboard – Ex of long distance extreme- Arctic Tern – Geese and swans – Europe and Asia- east to west – Very variable and complex Elliptical, sharp bends, nomadic wandering
Birds Influenza A – Highly segmented RNA virus – Infects most mammals and birds – Zoonotic after mammalian infection Effects of virus – Severe respiratory infections – Birds may be asymptomatic
Birds Transmission – Airborne through sneezing – Contact with bodily secretions – Birds to pigs to humans Environmental Factors – Fecal to oral transmission on farms
Birds West Nile Virus – Single stranded RNA - Flavivirus – Infects mainly birds, mosquito vector – Zoonotic Effects of virus – Asymptomatic – Fever – Encephalitis (rare)
Birds Transmission – From birds via mosquitoes – Airborne through sneezing – Contact with bodily secretions Environmental Factors – Warmer temperatures increase mosquito presence – Asymptomatic birds spread virus over distances
Birds Lyme Disease – Gram-negative spirochetal bacteria – Tick-borne disease – Deer and bird hosts – Zoonotic Effects of virus – Fever – Rash – Joint and muscle pain
Birds Transmission – Spread through deer ticks – Birds introduce ticks to new areas Environmental Factors
Bats Transmission – Airborne through sneezing – Contact with bodily secretions – Ingestion of contaminated meat Environmental Factors – Large populations in a small area increases spread of virus
Bats Lyssavirus and Rabies – Helical RNA viruses – Infects warm-blooded animals – Zoonotic Effects of virus – Attacks neural tissue Severe encephalitis Aversion to water – Death (~100% in untreated humans)
Bats Transmission – Blood, saliva, urine – Most common when saliva enters a bite wound Ecological Factors – Has cast a shadow on bats throughout the world. – Protocols put into place to prevent spread of these viruses (DEFRA: Pet Travel Scheme)
Bats Nipah/Hendra viruses – SS non-segmented RNA (Paramyxoviridae) – Infects flying foxes – Zoonotic Effects of virus – Acute respiratory illness (Hendra) – Severe encephalitis (Nipah) – Death
Bats Transmission – Body Fluids – Urine – Ingestion of contaminated meat – Bat migration spreads disease to new areas Notable Cases – 1994, Australian horses – 1998, Malaysian pigs
Cetacean Morbillivirus Overview – Single strand RNA virus of family Paramyxoviridae – Infects dolphins, porpoises, pilot whales – Not zoonotic Effects of virus – Pneumonia – Non-suppurative meningo-encephalitis – Lymphoid cell depletion – Death
Cetacean Morbillivirus Transmission – Pilot whales and other species thought to be reservoirs of infection, spreading the virus to other species Ecological Factors – Increased susceptibility if immunosuppressed and/or in poor nutritional state – PCBs and DDTs act as immunosuppresive agents – Exposure to natural neurotoxins (e.g. brevetoxin) – Increase in sea surface temperatures (global warming) decreases abundance of fish
Brucellosis Overview – Gram-negative bacteria of the genus Brucella – Infects marine mammals including whales, dolphins, porpoises and seals Effects of virus – Marine Mammals – Humans Fetal abortion Seizures Mastitits Recurrent fever Encephalitis Dramatic weight loss Pneumonia Intracerebral granulomas
Brucellosis Transmission – In marine mammals it is spread from mother to fetus – Interspecies and cross-species transmission – In humans, ingestion of infected foods and contact with possibly infected marine mammals Ecological Factors – Environmental factors in emergence of brucellosis is unknown
Toxoplasmosis Overview – Intracellular protozoan parasite of the family Toxoplasma gondii – Infects all mammals as well as arthropods ie mussels Effects of virus – Pneumonia – Encephalitis – Myocarditis
Toxoplasmosis Transmission – Wild and domestic felines are only known hosts – Feline fecal contamination flowing from land to sea – Ingestion of Contaminated food/drink – Transplacentally Ecological Factors – Degradation of marine environment leading to food scarcity – Immunosuppressed species more at risk
Why Should We Care? Prediction Prevention Conservation
“In humans, an estimated 75% ofemerging diseases are zoonotic, withwildlife representing a large and mostlyunknown resevoir.”