Lecture 39 11/26/24 Flashcards
What are the characteristics of influenza?
-classified into subtypes based on surface antigens
-hemagglutinin has 18 types
-neuraminidase has 11 types
How does HPAI differ from LPAI?
HPAI:
-causes severe disease in poultry
-only subtypes H5 or H7
-interspecies transmission from birds to mammals
-reportable and foreign animal disease
LPAI:
-causes mild disease in poultry
-contains other H subtypes, including non-HPAI H5 and H7
-LPAI H5 and H7 can mutate into HPAI
What are the characteristics of waterfowl as reservoirs?
-natural reservoirs for influenza A
-carry all known H and N antigens, usually in LPAI form
-predominant subtypes change periodically
What are the characteristics of antigenic drift?
-continual process
-point mutations in virus cause small changes
-reason flu vaccines are updated yearly
What are the characteristics of antigenic shift?
-sporadic event
-reassortment of 8 genome segments
-may result in new H or N surface proteins
What are the characteristics of influenza virus emergence in humans?
-avian and swine flu viruses do not normally infect humans
-frequent mutations occur through antigenic drift and shift events
-swine are proposed mixing vessels of influenza viruses
What are the characteristics of avian influenza in people?
-50-60% mortality
-clinical signs include fever, lower resp. disease, and diarrhea
What are the clinical signs of LPAI in birds?
-resp. disease
-decreased egg production
-secondary infections
-variable morbidity and mortality
What are the clinical signs of HPAI in birds?
-sudden death
-variable resp., GI, and neuro signs
-up to 100% mortality
How is avian influenza diagnosed?
-pathology
-PCR
-serology
-virus isolation
-in vivo determination of pathogenicity
How is avian influenza prevented in people?
-vaccine licensed by FDA but only for use in the event of an H5N1 outbreak
-do not handle birds that could be infected
-wear appropriate PPE
-vaccination in birds
What are the characteristics of canine influenza H3N8?
-horses long considered dead-end hosts
-equine influenza H3N8 first emerged in greyhounds in Florida
-HA of canine influenza virus contains 5 conserved amino acids that distinguishes it from equine influenza
-single trans-species transmission event with subsequent lateral spread between dogs
What are the characteristics of canine influenza H3N2?
-brought in by groups rescuing dogs from South Korea
-has also caused outbreaks in shelter cats
Who must be informed when reportable/foreign animal diseases are discovered?
-state veterinarian
-district veterinarian in charge (federal)
What are the characteristics of hantavirus?
-negative sense ssRNA bunyavirus
-Sin Nombre strain is most common in US
-Sin Nombre causes hantavirus pulmonary syndrome
-other strains can cause hemorrhagic fever with renal syndrome
What is the epidemiology of hantavirus in the US?
-case fatality rate of 36%
-most common in males
-average age of 38 years old
-typically occurs in caucasian individuals
-nearly all cases occur west of Mississippi River
-incubation of 1 to 5 weeks after exposure
What are the characteristics of hantavirus transmission?
-rodents are reservoirs
-humans and other mammals typically infected by inhaling virus particles from rodent urine, feces, and nests
-virus can also enter through broken skin, conjunctiva, other mucus membranes, rodent bites, or ingestion
What are the clinical signs during the initial phase of hantavirus pulmonary syndrome?
-fever
-myalgia
-headache
What are the clinical signs during the cardiopulmonary phase of hantavirus pulmonary syndrome?
-abrupt resp. distress
-cough
-tachypnea
-pulmonary edema
-cardiac abnormalities
What are the characteristics of hantavirus pulmonary syndrome disease progression?
-may be rapid after onset of cardiopulmonary phase
-may require hospitalization and mechanical ventilation
Which other symptoms can occur with hantavirus pulmonary syndrome?
-mild kidney disease
-hemorrhagic disease (rare)
How long is the incubation period for hemorrhagic fever with renal syndrome?
1 to 6 weeks
What are the disease stages in severe cases of hemorrhagic fever with renal syndrome?
-febrile
-hypotensive/proteinuric
-oliguric
-diuretic
-convalescent
What are the renal signs that occur with hemorrhagic fever with renal syndrome?
-proteinuria -> oliguria -> polyuria
-hypotension
-nausea and vomiting
-kidney failure
-lung or neurological signs
What are the characteristics of seoul virus?
-type of hantavirus
-typically causes no or mild symptoms
-can cause serious illness that requires hospitalization
How is seoul virus transmitted to people?
-contact with urine, droppings, or saliva of infected rats
-breathing in virus particles
-bitten by infected rat
How is seoul virus prevented?
-testing new rats before introduction into new home, especially multi-rat homes and breeding facilities
-keep wild rats away from pet rats
-do not recommend pet rodents for families with children younger than 5 years old, pregnant women, or immunocompromised individuals
What are the prevention steps for hantavirus?
-avoid rodents and their droppings
-wear a mask to prevent inhalation when working in potentially contaminated areas
-disinfect surfaces
What are the characteristics of Chlamydia psittaci?
-obligate gram neg. intracellular bacteria
-elementary and reticulate bodies
What are the different serovars of Chlamydia psittaci?
-A: endemic is psittacines, causes human cases
-B: endemic in pigeons and turkeys; causes abortion in cattle
-C/D: occupational hazards for slaughterhouse workers
What is the epidemiology of Chlamydia psittaci?
-worldwide
-true incidence unknown
-cases thought to be greatly underreported
-reportable disease in most states
How does Chlamydia psittaci transmit to humans?
-inhalation
-mouth to beak
-direct contact
-person to person/venereal
What are the characteristics of psittacosis in humans?
-incubation period of 1-4 weeks
-abrupt onset of clinical signs
-signs include fever, chills, headache, malaise, myalgia, sore throat, cough, dyspnea, splenomegaly, and rash
-can progress to pneumonia, endocarditis, myocarditis, or encephalitis
-treated with doxycycline or azithromycin
How is psittacosis diagnosed in humans?
-culture
-4 fold rise in paired titers
-PCR
What are the clinical signs of psittacosis in birds?
-incubation period of 3 days to 3 weeks
-often asymptomatic
-anorexia
-weight loss
-diarrhea
-yellowish droppings
-sinusitis
-resp. distress
-nervous signs
How are birds treated for psittacosis?
doxy for 45 days
What are the characteristics of psittacosis shedding?
-carriers may appear healthy and shed intermittently
-shedding activated by stress
-shedding is greatest in young birds
How is psittacosis diagnosed in birds?
-pathologic diagnosis
-culture
-antibody tests
-antigen tests
How is psittacosis prevented in humans?
-notifiable disease in most states
-purchase birds from reputable shops/sources
-wash hands regularly after handling
-do not touch birds’ beak or face to mouth
-do not keep psittacines if immunosuppressed
-disinfect cages
How is psittacosis prevented in birds?
-ended large scale importation
-quarantine of imports
-closed flocks
-records of all transactions
-quarantine all new birds joining flocks for 30 days
-acquire birds from reputable sources
-do not overcrowd
-disinfect surfaces
What is important for veterinarians to know about psittacosis?
-check state rules for reporting requirements
-inform clients, employees, and co-workers about zoonotic risks and how to mitigate them
-be aware of clinical signs in humans
-consider psittacosis in any lethargic bird
