Microbiology-Zoonotic Viral Diseases

Question 1

A mother brings in her 5 year old boy who has wart-like 5mm papular lesions on his face, back and buttocks. He is actively involved in gymnastics and swimming. His brother had similar lesions when he was 5 and they resolved after 6 months. What is causing his condition?

Answer 1

Poxvirus: Molluscum contagiosum, commonly spread via towels in swimming pools and gymnasiums.

Question 2

You are doing a humanitarian mission in Africa and see a man with a fever and severe headache for the past 3-4 days. Today the popular lesion popped up on his finger as shown below. His coworker had a similar infection that resolved after a month. What is causing his condition?

Answer 2

Poxvirus: Tanapox/Yabapox. Note the vesicular Orf lesion caused by sheep, goat, cow pox or vaccinia virus. These are commonly transmitted to humans from infected animals via arthropods.

Question 3

A young boy presents with the lesions shown below, fevers, sweats, malaise and sore throat. 15% of people who get this die and there is an immunization for it. What is causing his condition?

Answer 3

Orthopox: Monkeypox. Note that the infection can be transmitted by prairie dogs and the Gambian giant rat.

Question 4

What would you expect to see on EM of a patient infected with a poxvirus?

Answer 4

Brick-shaped virions in the cytoplasm

Question 5

A patient presents who was bitten by a bat with nausea, vomiting, fever and encephalitis. He later expires. What would you expect to see on EM of his peripheral nerves?

Answer 5

Rabies is an enveloped, -ssRNA, bullet-shaped rhabdovirus.

Question 6

Common animals that carry rabies

Answer 6

Skunks, foxes, bats and coyotes. Cats are the most common domestic animals with rabies in the US. Dogs are the most common worldwide.

Question 7

CNS findings in a patient infected with rabies?

Answer 7

Negri bodies (eosinophilic cytoplasmic inclusion bodies)

Question 8

Rabies Tx

Answer 8

If they have never been vaccinated, give both HRIG and vaccinate. Only give booster vaccination if vaccinated previously.

Question 9

Virus responsible for SARS

Answer 9

Coronavirus: enveloped +ssRNA virus

Question 10

SARS reservoir

Answer 10

Bats, they harbor lots of different types of coronaviruses

Question 11

A patient presents with pneumonia. She recently returned from a medical service mission in Asia. She is the 4th person from that group to present with atypical pneumonia. How should you proceed?

Answer 11

Her travel history, occupation and association with other atypical pneumonias increase suspicion for SARS-CoV and you should

Question 12

MERS-CoV reservoir

Answer 12

Camels

Question 13

What makes Hendra and Nipah viruses so virulent? What type of viruses are they?

Answer 13

They have broad tropism: ephrinB2/B3 receptors allow for infection of many cells. These are paramyxoviruses.

Question 14

How do humans get infected by Hendra and Nipah viruses?

Answer 14

Fruitbats infect animals and animals infect people.

Question 15

Clinical manifestations once you’ve been infected by Nipah or Hendra virus?

Answer 15

Widespread vasculitis, thrombosis, ischemia and necrosis. Most sever in the brain, lungs and spleen; resulting in severe respiratory distress and acute encephalitis w/brain necrosis.

Question 16

1st vaccine against BSL-4 agent for public use

Answer 16

Equivac HeV (against Hendra-sG soluble G glycoprotein subunit). Largely used in horses.

Question 17

Filoviruses

Answer 17

Ebola & Marburg

Question 18

Arenaviruses? Common vector?

Answer 18

Lass and South American Hemorrhagic fevers. Common vector is rat excreta.

Question 19

Bunyaviruses? Common vector?

Answer 19

Congo-Crimean Hemorrhagic Fever (CCHF), Rift valley fever and Hantaviruses-HFRS and HPS. Common vector is deer mouse excreta for hantavirus.

Question 20

All arboviruses and rodent-borne viruses are what?

Answer 20

RNA and enveloped (except reovirus, it is not enveloped)

Question 21

A patient presents with fever and malaise 10 days after returning from a trip in west Africa. A few days later he becomes nauseated, vomits, has abdominal pain, sore throat and chest pain. He also complains that he has lot his hearing. While in your office he begins hemorrhaging from all orifices and is taken to the ICU where he expires of shock. If Mastomys rodents were found in the place he stayed at in Africa, what is the likely cause of his condition?

Answer 21

Lassa fever. The rat is the natural reservoir and people get infected by contact with rat urine and feces. Human to human transmission is possible.

Question 22

Arenavirus characteristics

Answer 22

Enveloped, grainy appearance from ribosomes and 2 strands of ambisense RNA

Question 23

A patient presents with fever, malaise, anorexia, myalgias and headache. Symptoms go away for a few days, then he comes back with a fever, headache, stiff neck, confusion, paralysis, sensory disturbances and seizures. In his house he has pet hamsters and mus musculus (common house) mice. What is causing his condition?

Answer 23

Lymphocytic choriomeningitis virus (LCMV). The 1st and 2nd phases are seen in this patient.

Question 24

Virus that is likely an under-recognized cause of pregnancy complications

Answer 24

LCMV: associated with abortion, congenital hydrocephalus, chorioretinitis and retardation

Question 25

Hantavirus characteristics

Answer 25

Enveloped -ssRNA w/3 segments. Transmitted by direct inhalation of rodent excrement or direct skin contact.

Question 26

A patient presents with fever, headache, back pain, chills, blurred vision and rash 2-3 days after cleaning out his garage. On day 5 he become hypotensive and day 9 he develops renal failure, hemorrhage and goes into shock. Deer mice are found in the garage. What is causing his symptoms?

Answer 26

Hantavirus: hemorrhagic fever with renal syndrome (HFRS). There is also a hantavirus pulmonary syndrome (HPS, Sin Nombre Virus) that predominately damages the lungs (below) over the kidney.

Question 27

5 stages of hantavirus infection

Answer 27

1) Febrile 2) Hypotensive 3) Oliguric 4) Diuretic 5) Convalescent

Question 28

Arbovirus with 3 segmented genome

Answer 28

Bunyaviruses

Question 29

Arbovirus with no envelope and 12 segmented dsRNA genome

Answer 29

Reovirus

Question 30

Arbovirus that is bullet shaped

Answer 30

Rhabdovirus

Question 31

Diseases transmitted by the Aedes mosquito

Answer 31

Dengue, Yellow Fever, VEE (rodent reservoir), EEE (bird reservoir), Rift Valley Fever

Question 32

Diseases transmitted by the Culex Mosquito

Answer 32

Japanese (bird and pig reservoir), West Nile and St. Louis Encephalitis, WEE

Question 33

Diseases transmitted by the sandfly

Answer 33

Sicilian Sandfly Fever, Toscana Virus

Question 34

A patient presents with fever, rash, aches and chills. Later he becomes confused and develops encephalitis. He lives next to a pond with lots of mosquitos. How would you narrow your diagnosis and what vaccines are available for these diseases?

Answer 34

Serology is usually used to diagnose arbovirus infections. PCR can be used. Vaccine is available for yellow fever, Japanese encephalitis and West Nile is in the pipeline.

Question 35

What type of virus is West Nile Virus? What other important viruses are in this family?

Answer 35

+ssRNA flavivirus. Japanese encephalitis, yellow fever and dengue are also in this family.

Question 36

2 types of yellow fever

Answer 36

Jungle: cycles between non-human primates and mosquitos, humans infected when going into jungle. Urban: transmitted by Aedes mosquito.

Question 37

Global distribution of yellow fever

Answer 37

South America and West Africa

Question 38

Who proved that the secret to stopping epidemics of yellow fever is to get rid of the mosquitos that carry it?

Answer 38

Walter Reed

Question 39

A patient presents with chills, fever, headache, malaise, myalgias, jaundice and black vomit from GI hemorrhage. Serology reveals yellow fever. When should be people be vaccinated against this?

Answer 39

It is a live attenuated vaccine that has rare side effects of yellow fever-like symptoms. Consequently it should only be given when people are traveling to or living in areas endemic with yellow fever.

Question 40

A patient presents with high fever, lymphadenopathy, myalgias, arthralgias, headache, maculopapular rash, hemorrhage and shock. He lives near standing water and is thought to have dengue. What is responsible for his hemorrhage and shock?

Answer 40

There are 4 dengue serotypes. People usually have more severe infections when they have been previously infected by a different serotype.

Question 41

What type of viruses are the equine encephalitis viruses?

Answer 41

Togaviruses

Question 42

A patient presents with a flu-like illness that progresses to encephalitis 3-10 days after infection. The infection clears but he is left with sequelae of paralysis and mental retardation. Serology shows a togavirus. What are likely causes of his condition?

Answer 42

WEE (more common), EEE (infrequent), VEE (CNS less common and less severe). Note that all of these infections are typically asymptomatic.

Question 43

Most important cause of pediatric arbovirus encephalitis in the US

Answer 43

La Crosse Virus, a bunyavirus

Question 44

A patient from the Pacific Northwest presents with fever, chills, headache, myalgia, arthralgia, photophobia and lethargy. He develops hemorrhagic disease. A wood tick is found on his back. What is likely causing his condition? How do you narrow your diagnosis?

Answer 44

Colorado Tick Fever Virus, a reovirus. This virus is in many animal reservoirs and infects erythroid precursor cells. Hemorrhagic disease results from infection of vascular endothelium. Diagnosis with immunofluorescence on blood smear.