Zoonotic Diseases of SouthWest Flashcards
presence of zoonotic diseases in AZ is exacerbated by
- diversity in wildlife species
- disparities across communities
- extreme climates
- varrying topography
- close proximity to international border
in AZ, tularemia circulates naturally among _____ and ______ and is usally found in areas above _______feet
rabbits and rodents
3,000 feet
Cases of tularemia in AZ have been related to exposure to what
rabbit or rabbit carcass, dog that was exposed to rabbit carcass, skinning elk, potentially from insect bites
Tularemia Agent
Francisella tularensis a gram (-) bacteria
T/F: tularemia is considered a potential bioterrorism weapon
T
most reported worldwide zoonoses
- Rabies 55,000+
- Leishmaniasis >2 million
- Cysticercosis ~50,000 deaths
- Brucellosis ~500K
* Leptospirosis ~10 million
common zoonoses of the Southwest (6)
- Tularemia
- Rocky Mountain spotted fever (vectored by brown dog tick)
- Chagas
- Onchocerca lupi
- hantavirus
- plague
what is the third most common reported laboratory-associated bacterial infection
tularemia
tularemia incubation period
3-5 on average
but can be 1-14
how is tuleremia transmitted
drainage from tulameria lesion
flies can remain infective for 2 weeks
ticks remain infective throughout their lifetime
not directly transmitted from person to person
clinical diagnosis of tularemia
evidence or history of a tick or deerfly bit, exposure to tissue of mammalian host or exposure to contaminated water
tularemia symptoms
- sudden fever
- chills
- headache
- D+
- muscle aches/joint pain
- dry cough
w/out txt, can result in respiratory failture, shock, death
differential diagnosis for tularemia is…
plague
most common form of tularemia
Ulceroglandular
- usually following tick or deer fly bite or handling infected animal
- cutaneous ulcer w/ regional lymphadenopathy
regional lymphadenopathy w/ no ulcer (tularemia)
Glandular
Oculoglandular tularemia
- bacteria gets into eye during butchering or touching eye
- conjunctivitis w/ preauricular lymphadenopathy
Tularemia from eating/drinking contaminated food/water. Characterized by stomatitis, pharyngitis, tonsilitis, cervical lymphadenopathy
Oropharyngeal
most serious form of tularemia, caused by breathing dust or aerosols containing the organism
penumonic
primary pleuropulmonary disease
febrile (fever) illness w/out early localizing signs/symptoms (tularemia)
Typhoidal
Type A tularemia infections may be acquired from _____or_____
rabbits, ticks
A.II strains localizeed to western US
type B tularemia infections are often associated w/ hosts such as….?
rodents and hares
Tularemia mode of transmission
- bite from certain arthropods
- inoculation of skin, conjunctival sac, oropharyngeal mucosa w/ contaminated water, blood, tissue while handling infected animals
- handling/ingesting insufficiently cooked meat of infected host
- inhalation of dust from contaminated soil/grain/hay
- contaminated pelts and paws of animals
- rarely from bites of animals that ate an infected animal
tularemia treatment
- antibiotics
- 14-21 days
- symptoms may last for weeks but mosst patients completely recover
All confirmed, probable or suspect tularemia cases must be reported to ______ within 4 hours
AZDA
Tularemia prevention
inspect yard before mowing to avoid sick / dead animals
use dust masks
use insect repellent w/ 20-30% DEET
wear long pants, sleeves and sock to keep ticks and deer flies away
remove ticks asap
hunters wear gloves while skinning
drink only treated water while camping
Rocky Mountain Spotted Fever (RMSF) is vectored by…
brown dog tick
most severe disease caused by tick in USA
RMSF
Notifiable to CDC
5-10% of cases are fatal
state in US w/ most cases of RMSF
AZ, mostly in communities w/ lots of roaming dogs
what organism causes RMSF
Rickettsia rickettsii, gram (-) obligate intracellular parasite
how is R.rickettsii transmitted? what is the incubation period?
bite of an infected tick
4-5 days most common but can be 2-14 days
R. rickettsii invades ____Cells of the venules and capillaries, causing _______
endothelial cells, causing vasculitis
RMSF clinical signs
Fever, severe lethargy
petechiae and ecchymoses on mucous membranes
focal retinal hemorrhages
edema of extremities
about 60% of cases have rashes but rash is uncommon in AZ
late stage clinical signs of RMSF
necrosis, abdominal pain, V+, anorexia
altered mental status
myalgia or polyarthritis
vestibular deficits
dyspnea or cough
Abnormal clinical findings associated w/ RMSF
hypoalbuminemia
moderate leukocytosis
thrombocytopenia
signs may resemble infection w/ Ehrlichia canis (which is also transmitted by brown dog tick)
gold standard for RMSF diagnosis
indirect immunofluorescence assay (IFA) w R. rickettsii antigen, performed on 2 paired serum samples to demonstrate 4 fold rise in antibody titers
PCR testing
RMSF treatment
doxycycline
mortality is related to incorrect txt or delayed diagnosis
prompt use of antibiotics reduces severity of illness
RMSF prevention
prevent tick attachment, promptly remove if it occurs
topical or systemic tick control prevention
seasonal tick/flea dips
collars w/ amitraz or propoxur
txt of kennels/yards w/ acaricidal
Primary domestic reservoir of chagas
dogs
how many people in Mexico, central and south America are suspected to have Chagas
8 million
if untreated, infection is lifelong and can be life threatening
chagas disease is caused by….
protozoan parasite: Trypanosoma cruzi, transmitted to animals and people by insect vectors
T/F: Chagas is only found in the Americas
T
Chagas transmission to humans
vector-borne infected triatomines (kissing bugs) - feces contains parasite, enters through bite or mucous membranes
congenital transmission (mother to fetus)
blood transfusion
organ transplantation
oral ingestion (Contaminated foods or acai, palm fruit, guava juice, sugarcane juice)
presence of Chagas in AZ
up to 1/2 of all kissing bugs have it but no confirmed cases from bug bites
Acute phase of Chagas (clinical signs)
acute phase = first few weeks-months of infection
fever, fatigue, body ache, rash, D+/V+
some may have Romana’s sign (swelling of eyelids near bite wound)
young children or immunocompromised people may die from myocarditis or meningoencephalitis
Chronic phase of Chagas
lasts decades - lifetime
20-30% develop cardiac or GI complications
Chagas diagnosis
during acute phase, can look for trypomastigotes in blood of CSF (PCR)
chronic phase - serologic testing
Chagas treatment
antiparasitic txt (benznidazole or nifurtimox) kills parasite
symptomatic txt to manage symptoms
monitor heart w/ heart tracing test
Chagas disease in dogs is a diagnostic differential in dogs w/….?
arrhythmias, myocardial dysfunction, congestive heart failure
can present w/ findings like dilated cardiomyopathy, arrhythmogenic R ventricle cardiomyopathy, infectious myocarditis, congenital tricuspid valve dysplasia
Risk factors for Chagas in dogs
living or traveling in areas w/ infected insect vectors
dogs that live outside or do outdoor work
dog kennels
high densities of dogs in confined areas w/ heat and CO2 (attract kissing bugs)
Chagas prevention
turn off outdoor lights
clean up brush
house dogs inside
use insecticides
do traditional flea/tick repellants repel kissing bugs?
NO
Onchocera lupi was first described…?
wolf in Georgia, 1967
has been identified in US since 2013 (possibly came from dogs from Europe)
Onchocerca lupi most commonly infects…
dogs, cats, and humans in US (primarily southwestern states)
considered an emerging zoonosis
organism that causes Onchocerca lupi
Filarial nematode
adults embedded in ocular nodules and granulomatous masses of infected dogs
suspected arthropod vector of Onchocerca lupi
black fly or biting midge
this disease involves infection in the eyes, joints, limbs and upper cervical spine (masses) in humans
Onchocerca lupi
clinical symptoms of Onchocerca lupi in dogs
most are asymptomatic, esp if the worm is localized to the retrobulbar space of the eye (can’t be detected during ophthalmic exam)
Clinical diagnosis of Onchocerca lupi
detection of ocular nodules in the sclera or conjunctiva
subconjunctival threadlike parasites
histopathological identification of adult worms
microfilariae from skin snip biopsies
in vivo confocal light microscopy
Onchocerca lupi treatment
currently no evidence-based protocols
Drugs are administered based on treatments against other filarial parasites, mainly O. volvulus
if possible, surgical excision of periocular nodules
reoccurrences common
Hantavirus occurrence in AZ
sporadically in rural areas, usually in northern regions but infected rodents can be found statewide
first discovered at 4 corners in 1993
when was plague first introduced to US
1900 by rat infected steamships coming from Asia
epidemics occurred in port cities
