Lecture 39 11/26/24

Question 1

What are the characteristics of influenza?

Answer 1

-classified into subtypes based on surface antigens
-hemagglutinin has 18 types
-neuraminidase has 11 types

Question 2

How does HPAI differ from LPAI?

Answer 2

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

Question 3

What are the characteristics of waterfowl as reservoirs?

Answer 3

-natural reservoirs for influenza A
-carry all known H and N antigens, usually in LPAI form
-predominant subtypes change periodically

Question 4

What are the characteristics of antigenic drift?

Answer 4

-continual process
-point mutations in virus cause small changes
-reason flu vaccines are updated yearly

Question 5

What are the characteristics of antigenic shift?

Answer 5

-sporadic event
-reassortment of 8 genome segments
-may result in new H or N surface proteins

Question 6

What are the characteristics of influenza virus emergence in humans?

Answer 6

-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

Question 7

What are the characteristics of avian influenza in people?

Answer 7

-50-60% mortality
-clinical signs include fever, lower resp. disease, and diarrhea

Question 8

What aer the clinical signs of LPAI in birds?

Answer 8

-resp. disease
-decreased egg production
-secondary infections
-variable morbidity and mortality

Question 9

What are the clinical signs of HPAI in birds?

Answer 9

-sudden death
-variable resp., GI, and neuro signs
-up to 100% mortality

Question 10

How is avian influenza diagnosed?

Answer 10

-pathology
-PCR
-serology
-virus isolation
-in vivo determination of pathogenicity

Question 11

How is avian influenza prevented in people?

Answer 11

-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

Question 12

What are the characteristics of canine influenza H3N8?

Answer 12

-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

Question 13

What are the characteristics of canine influenza H3N2?

Answer 13

-brought in by groups rescuing dogs from South Korea
-has also caused outbreaks in shelter cats

Question 14

Who must be informed when reportal/foreign animal diseases are discovered?

Answer 14

-state veterinarian
-district veterinarian in charge (federal)

Question 15

What are the characteristics of hantavirus?

Answer 15

-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

Question 16

What is the epidemiology of hantavirus in the US?

Answer 16

-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

Question 17

What are the characteristics of hantavirus transmission?

Answer 17

-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

Question 18

What are the clinical signs during the initial phase of hantavirus pulmonary syndrome?

Answer 18

-fever
-myalgia
-headache

Question 19

What are the clinical signs during the cardiopulmonary phase of hantavirus pulmonary syndrome?

Answer 19

-abrupt resp. distress
-cough
-tachypnea
-pulmonary edema
-cardiac abnormalities

Question 20

What are the characteristics of hantavirus pulmonary syndrome disease progression?

Answer 20

-may be rapid after onset of cardiopulmonary phase
-may require hospitalization and mechanical ventilation

Question 21

Which other symptoms can occur with hantavirus pulmonary syndrome?

Answer 21

-mild kidney disease
-hemorrhagic disease (rare)

Question 22

How long is the incubation period for hemorrhagic fever with renal syndrome?

Answer 22

1 to 6 weeks

Question 23

What are the disease stages in severe cases of hemorrhagic fever with renal syndrome?

Answer 23

-febrile
-hypotensive/proteinuric
-oliguric
-diuretic
-convalescent

Question 24

What are the renal signs that occur with hemorrhagic fever with renal syndrome?

Answer 24

-proteinuria -> oliguria -> polyuria
-hypotension
-nausea and vomiting
-kidney failure
-lung or neurological signs

Question 25

What are the characteristics of seoul virus?

Answer 25

-type of hantavirus
-typically causes no or mild symptoms
-can cause serious illness that requires hospitalization

Question 26

How is seoul virus transmitted to people?

Answer 26

-contact with urie, droppings, or saliva of infected rats
-breathing in virus particles
-bitten by infected rat

Question 27

How is seoul virus prevented?

Answer 27

-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

Question 28

What are the prevention steps for hantavirus?

Answer 28

-avoid rodents and their droppings
-wear a mask to prevent inhalation when working in potentially contaminated areas
-disinfect surfaces

Question 29

What are the characteristics of Chlamydia psittaci?

Answer 29

-obligate gram neg. intracellular bacteria
-elementary and reticulate bodies

Question 30

What are the different serovars of Chlamydia psittaci?

Answer 30

-A: endemic is psittacines, causes human cases
-B: endemic in pigeons and turkeys; causes abortion in cattle
-C/D: occupational hazards for slaughterhouse workers

Question 31

What is the epidemiology of Chlamydia psittaci?

Answer 31

-worldwide
-true incidence unknown
-cases thought to be greatly underreported
-reportable disease in most states

Question 32

How does Chlamydia psittaci transmit to humans?

Answer 32

-inhalation
-mouth to beak
-direct contact
-person to person/venereal

Question 33

What are the characteristics of psittacosis in humans?

Answer 33

-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

Question 34

How is psittacosis diagnosed in humans?

Answer 34

-culture
-4 fold rise in paired titers
-PCR

Question 35

What are the clinical signs of psittacosis in birds?

Answer 35

-incubation period of 3 days to 3 weeks
-often asymptomatic
-anorexia
-weight loss
-diarrhea
-yellowish droppings
-sinusitis
-resp. distress
-nervous signs

Question 36

How are birds treated for psittacosis?

Answer 36

doxy for 45 days

Question 37

What are the characteristics of psittacosis shedding?

Answer 37

-carriers may appear healthy and shed intermittently
-shedding activated by stress
-shedding is greatest in young birds

Question 38

How is psittacosis diagnosed in birds?

Answer 38

-pathologic diagnosis
-culture
-antibody tests
-antigen tests

Question 39

How is psittacosis prevented in humans?

Answer 39

-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

Question 40

How is psittacosis prevented in birds?

Answer 40

-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

Question 41

What is important for veterinarians to know about psittacosis?

Answer 41

-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