Zoonotic Diseases

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Zoonotic Diseases

• Lecture 5
• Dr. Paul Bartlett, MPH., DVM., Ph.D.

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Hantavirus Pulmonary Syndrome (HPS)

• The first recognized cases occurred in May of
  1993, in the four corners area of the southwest
  USA.
• New Mexico, Arizona, Colorado, Utah
• Through June 6, 2002 there have been a total of
  318 cases of HPS in the USA.
• 38 of all reported cases have resulted in death
• Cases have been reported in 31 states, including
  most of the western ½ of the country, and some
  eastern states
• Over half of the cases of HPS are found outside
  the four corners area.

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Hantavirus Pulmonary Syndrome

• Cases of HPS have also been confirmed from
  Argentina, Bolivia, Brazil, Canada, Chile,
  Panama, Paraguay, and Uruguay.
• HPS is classified as a pan-American zoonosis
• HPS has also been linked with hypertensive renal
  disease in the inner city

Carriers in the USA and the virus they transmit
Deer Mouse Sin Nombre virus - most often Cotton
rat (Florida) Black canal virus Rice rat
(Louisiana) Bayou virus White footed mouse (New
York) SNV
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Bat viruses in Australia

• All of the newly identified viruses are
  Rhabdoviruses which are related to the viruses
  that cause rabies and Lyssa fever.
• Viruses in this family have a high fatality rate
  often near 100
• Henda Virus (Equine Morbillivirus) - infects
  humans, horses, cats and Guinea pigs. Fruit bats
  are the natural reservoir.
• Fast response to outbreak in Australia
• Australian bat lyssa viruses (Ballina virus) -
  this is a close relative of rabies
• Menangle virus - carried by fruit bats and causes
  disease in pigs

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Dog and Cat Roundworms

• (See assigned reading)
• http//www.dpd.cdc.gov/dpdx/HTML/Toxocariasis.htm
  
• (All 6 parts Causal agent through Treatment)

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Raccoon Roundworms (Baylisascaris procyonis)

• Common intestinal roundworm of raccoons
• Eggs deposited in raccoon feces (infective in
  thirty days)
• Ingested by man or other animal
• Aggressive migration (eyes, brain, other tissue)
• Fatal nervous system disease, eye disease in
  intermediate host (mice, squirrel, chickens,
  quail, man etc.)
• Encyst and await ingestion by raccoon scavenger.

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Raccoon Roundworms (Baylisascaris procyonis)

• http//www.cdc.gov/mmwr/preview/mmwrhtml/mm5051a1.
  htm
• (Skim the two cases, but read the Editorial
  Note)

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Raccoon RoundwormsTransmission of Baylisascaris
to Humans

• Eggs shed in raccoon feces, infective in 30 days
• Hatch after ingestion, penetrate intestinal wall
• Migrate to liver, lungs and muscle
• Encyst in small fibrous nodules causing no
  further problems or
• Some enter the brain and eyes and cause disease.

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Raccoon RoundwormsPrevalence of Baylisascaris in
Raccoons

• 50- 89 of raccoons have the worm
• One study of 520 raccoons 70 of all age groups
  and 88 of juvenile raccoons were infected.
• Eggs are very resistant and can survive three to
  five years.
• Serious infection is rarely diagnosed lt30 cases
  reported. Probably many undiagnosed cases.

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Raccoon RoundwormHuman infection

• Ocular infection
• Primate research multifocal retinal
  hemorrhages, white spots, chorioretinitis,
  inflammatory tracks, vascular sheathing, and
  diffuse retinal degeneration
• Reaches eyes by 7 days post-ingestion
• Diagnosis of Baylisascaris infection
• History of pica, raccoon exposure
• Serology (still experimental- ELISA Indirect
  immunofluroescent test).
• Difficult to diagnose in a living person but in
  ocular cases there is often a diagnostic lesion
  in the eye.

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Raccoon RoundwormsControl and/or Prevention of
Baylisascaris

• Disinfectants for contaminated areas (heat or
  lipid solvents)
• Discourage raccoon ownership (pets)
• Regularly de-worm raccoons at zoos, wildlife
  exhibits, etc.
• Discourage raccoons from living near people by
  removing sources of food and/or shelter

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Other Similar Roundworm Species

• Skunk roundworm (Baylisascaris columnaris)
• Poorly understood
• Kills mice, rabbits, and woodchucks by CNS
  migration
• Infection of man is unknown

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Viral Hemorrhagic Fever

• Caused by a number of viruses Lassa, Marburg,
  Ebola, and Congo-Crimean Hemorrhagic Fever
• Most are transmitted by direct contact of bodily
  fluids in the later stages of the disease
• Vomiting, diarrhea, shock and hemorrhage.
• not transmissible via air.
• Caregivers often infected.
• Ebola and Marburg are RNA viruses in the
  filovirus family.

Electron micrograph of Ebola virus. 
biosafety level four (BSL-4) pathogens
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Marburg

• First occurred in Germany in 1967 when Laboratory
  workers were exposed to infected monkeys from
  Uganda.
• Non-human primates can be infected but they are
  not considered to be the natural reservoir.
• The natural reservoirs for this virus is unknown.

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Ebola

• First discovered in 1976 near the Ebola river.
• There are four known types of the Ebola Zaire,
  Sudan, Ivory Coast, and Reston
• The Zaire and Sudan strains are associated with
  disease in humans.
• Incubation period is up to 3 weeks.
• Initial clinical signs include fever, headache,
  chills, myalgia, and malaise. Later abdominal
  pain, vomiting, diarrhea and occasionally a
  maculopapular rash are seen. Hemorrhagic
  manifestations with disseminated intravascular
  coagulation can be observed in fatal cases.

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Zaire and Sudan strains (Continued)

• 50- 90 fatality has been reported.
• Since its discovery in 1976, Ebola has killed
  more than 800 people.
• Due to the high fatality of the disease, the
  outbreaks have not become large.

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Zaire and Sudan strains (Continued)

• Like Marburg, the natural reservoir is unknown
  but human cases are often preceded by large
  die-offs of non-human primates. Epidemiologists,
  including veterinarians, are currently
  investigating many sources including plants as
  possible vectors.
• The last known cases of Ebola occurred in The
  Republic of the Congo and Gabon in late 2001 to
  2002.
• As of 4/1/2002, these outbreaks took the lives of
  96 people in 122 known cases (WHO).

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Personal Safety Issues

• Veterinarians chasing around the jungle for Ebola
• EIS Track record
• Outbreak the movie

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Ebola - Reston (The Hot Zone)

• This strain of Ebola was discovered in Reston,
  Virginia in 1989.
• It was first identified in monkeys from the
  Philippines.
• Ebola-Reston is often fatal in monkeys, in four
  known cases in humans however the virus evokes an
  immune response but was asymptomatic.
• Four episodes of Ebola-Reston infection among
  monkeys imported from the Philippines have
  occurred in the USA and Italy.
• Aerosol spread, while not documented in humans,
  has been seen in non-human primates.
• Very scary!

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Brucellosis

• Undulant Fever, Mediterranean Fever, or Malta
  Fever.
• Species of Brucella and the usual host.
• B. canis in dogs
• B. melitensis in goats and sheep
• B. suis in pigs
• B. abortus in cattle
• B. melitensis is the most virulent in humans and
  infection
• is usually associated with unpasturized dairy
  products
• from Mediterranean countries or Mexico
• Incidence of human infections
• 1947 - 6300 cases a year
• 1990 about 100 cases a year (but only 4 to 10
• are recognized and reported).

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Brucellosis

• Human cases
• Incubation period- usually 30 days but can be up
  to 5 months
• Symptoms - non-specific. Fever, chills, headache,
  myalgia, arthralgia, anorexia, fatigue,
  lymphadenopathy and splenomagaly. The ratio to
  subclinical to clinical cases is 11 to 121.
• Treatment - many different antibiotics -
  Doxycycline Occupational exposures are common.
  Occupational exposure is seen among packing plant
  workers, veterinarians, livestock producers, and
  laboratory workers. Vets used to get strain 19
  (vaccine)
• Exposures occur through breaks in the skin,
  inhalation and conjunctival contact.

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Brucellosis

• Prevention
• Reduce exposure by controlling the disease in the
  animal population.
• Public health efforts to ensure the proper
  pasteurization of dairy products.
• Eradication Programs
• Cattle Brucellosis program - the goal is
• eradication. Most of the infected herds are
  in Texas and the South Eastern states.
• Swine Brucellosis program Nearly eradicated
  from US.

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Bartonellosis

• Two diseases Cat Scratch Disease and
  Bacillary Angiomatosis.
• Cat Scratch Disease has been described for 100
  years. The agent, slightly curved gram negative
  rods, was identified in 1988.
• The agent has been placed in the genus Bartonella
  
• may be related to the agents which cause Typhus,
  RMSF, tsutsugamushi, Q fever, Brucella, and
  Richettsia quintana.

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CSD

• The disease is subclinical in cats.
• Transmission to humans
• Following cat bites, scratches, and possibly
  bites
• from cat fleas.
• Cat saliva over an area of compromised skin
  integrity may also lead to infection.
• Kittens are more likely to infect people because
  they scratch more often and have a higher
  prevalence of Bartonella.
• Prevalence in cats of all ages can be 30 to 50.

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CSD

• An estimated 22,000 cases occur in the USA each
  year.
• First a 2-3 mm macule occurs at the site of
  exposure. The macule becomes papular within a few
  days.
• The duration of the disease is usually several
  weeks
• Regional lymphadenopathy may develop with fever,
  fatigue, and headache.
• Clinically it can look similar to tularemia or
  bubonic plague.

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CSD

• 14 of cases can progress to more severe symptoms
  which can include eye problems, encephalopathy,
  arthritis, osteolysis, vascular system lesions,
  hepatitis, or pneumonia.
• Treatment
• Uncomplicated cases resolve on their own.
• Antibiotics are effective in more severe cases.

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Bacillary Angiomatosis

• Mostly in HIV - infected and other
  immuno-suppressed individuals.
• Much more severe disease than is CSD.
• Vascular lesions may involve many organs, with
  skin being the most common.
• Prevention
• Wash hands after handling cats.
• Do not encourage rough play with cats.
• Use flea control.
• Do not let cats lick areas of abraded skin or
  open wounds.
• HIV patients may wish to avoid being scratched by
  cats.

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Are CSD and Bacillary Angiomatosis caused by the
same agent?

• Despite the similarities in histochemical
  staining properties and epidemiology, serious
  reservations remained concerning a possible link
  between the causative agents of CSD and BA.
• The pathologic features of classical CSD
  (granuloma) and BA (proliferative vascular
  lesions without granuloma) are distinctly
  different.
• The two diseases seem to respond differently to
  antibiotic therapy.
• The majority of BA patients evaluated responded
  quickly to single-agent therapy with either
  erythromycin or doxycycline (14,23), whereas the
  symptoms and signs of patients with CSD failed to
  show consistent rapid resolution following
  antibiotic therapy.

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Rat Bite Fever

• The responsible agent is Streptobaccilus
  moniliformis (more common in U.S.) or
  spirillary RBF by Spirillum minus
• Nasopharyngeal carriage rates in healthy
  laboratory rats range from 10 to 100 carriage
  rates in wild rats range from 50 to 100
• Transmission is usually through a rat bite.
  However, some cases have rat exposure but no
  reported bite.
• Ingestion of food contaminated with rat feces
• Children and laboratory workers are at high risk
  to contract this disease.
• Cases are rarely reported in the United States
  and the true incidence of disease is unknown.

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Rat Bite Fever

• Clinical syndrome 2-10 days after rat bite.
• Usually a mild protracted illness with a fever,
  malaise, cough, maculopapular rash, and
  occasionally arthritis.
• Human fatalities have been reported.
• Antibiotics are effective (Shot gun) Susceptible
  to penicillin
• diagnosed by blood culture only.

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Lymphocytic Choriomeningitis Virus (LCMV)

• The main reservoir is the house mouse (Mus
  musculus) but hamsters and domestic mice can also
  be infected.
• Infection in people
• Often subclinical.
• influenza-like symptoms but sometimes meningeal
  symptoms of a stiff neck, fever, headache,
  malaise, and muscular pain.
• Incubation period - 1 to 2 weeks.
• Pregnant women may transmit the disease to the
  unborn fetus resulting in fetal or neonatal
  death, hydrocephalus, chorioretinitis, or
  psychomotor retardation.
• Usually a history of a febrile illness during
  their pregnancy.

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LCMV

• Prevalence- a study in Baltimore showed that 9
  of house mice and 4.7 of residents had LCMV
  antibody
• Transmission
• Contact with mouse nasal secretions, urine,
  semen, milk, and feces
• Mouse and hamster bites.
• Humans become infected by inhaling infectious
  aerosolized particles of rodent urine, feces, or
  saliva, by ingesting food contaminated with
  virus, by contamination of mucus membranes with
  infected body fluids, or by directly exposing
  cuts or other open wounds to virus-infected
  blood.

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LCM

• Risk factors
• Recreational activates in rural environments.
• Habitation in older rodent-infected homes.
• Acquisition of rodents for pets
• Laboratory exposure to unscreened rodents (rare)
• Pregnant women risk exposure to their unborn
  children.

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LCMV

• Epidemiology of LCMV in mice
• Much studied, interesting epidemiology, when LCMV
  is introduced to a non-infected colony.
• Adult mouse infection shows some morbidity, but
  most recover and no longer shed the virus.
• Infections acquired in utero lead to a persistent
  tolerant infection with heavy shedding throughout
  their lives (similar to BVD in cattle).
• Over time, the infection was only transmitted
  congenitally in that all mice had been infected
  before they were born.
• It appeared that transovarian infection was the
  rule, rather than the exception.

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LCMV

• Prevention
• Control the mouse population in houses.
• Dont touch dead mice.
• Pregnant women should avoid hamsters, and other
  rodents.
• Most all laboratory animal colonies in the US are
  LCMV-free.