Med Micro 2 Exam 2

How do trypanosomes evade the immune system?

By modifying their surface membranes (antigenic variation)

Identify the definitive host for Toxoplasma gondii:

Cats

Which of the following could be a fatal long term consequence of the above organisms?

PRP

Which subspecies of trypanosoma brucie invade the CNS more frequently?

Rhodesiense more common than gambeinse

What is Romana's sign?

Unilateral painless swelling around the orbit caused by Chagas disease

What type of infection causes the sleepy Africans?

Vector-born parasitic

What type of tissues does trypanosoma cruzi prefer?

Mesenchymal fat, cardiac/aorta, CNS, RE systems

Without treatment, what is the usual outcome with African sleeping sickness?

fever?

How does clostridium botulinum prevent action potential propogation at the neuromuscular junction?

proteolytic cleavage of synaptic vesicle peptides

Which of the following organisms should you suspect in a case of fatal fulminant meningoencephalitis of a 7 year old boy from swimming in a pond?

Acute bacterial meningitis

What are the mechanisms of action for the tetanospasmin tetanus toxin?

Blocks neurotransmitter release at inhibitory synapses permanently contracted muscles

A child is immunized against Polio with the killed-virus (Salk) vaccine. This vaccine produces immunity to Polio by stimulating production of neutralizing antibody. What is the locating of the epitopes bound by these neutralizing antibodies?

Envelope glycoproteins

What is Winterbottom's sign?

Swelling of lymph nodes along the back of the neck seen in the early phase of African trypanosomiasis

How does Nagleria fowleri gain access to the CNS?

Through the cribiform plate - causes olfactory nerve necrosis

Your patient is a young woman who wishes to become pregnant. Because of the risk to the fetus in a primary infection of a non-immune mother, for what parasitic protozoan should you check her immune status?

Toxoplasma gondii

A cyanotic, listless, infant with extremely poor muscle tone is brought to the Emergency Room. Which condition is most likely?

A. Botulism

A 64 year old man has a history of chronic neurological symptoms over the preceding eight months, memory, cognition, and motor control are all affected. If this is Creutzfeldt-Jacob disease, what would you expect to observe in a brain biopsy?

Aggregates of bovine protein

What are the characteristics of clostridium botulinum?

Anaerobic, gram positive, spore-forming bacillus

A missionary returning from work in Central America is at risk of being bitten by an arthropod carrying which of the following protozoa?

B. Trypanosoma cruzi

In immunocompromised hosts what area of the brain is most commonly affected by toxoplasma gondii?

Basal ganglia - causes headaches, confusion, and focal neurologic deficits

A 55 year old woman developed diplopia, one day after eating home canned fruit. (Diplopia = double vision, from inability to coordinate the direction of gaze of the eyes.) A few hours later she develops difficulty speaking, bilateral weakness of her arms, nausea, vomiting, dizziness, blurred vision, and dry mouth. However she is alert, oriented, and has no fever. Choose the best diagnosis

Botulism

Being bitten by a tsetse fly (genus Glossina) would transmit which of the following disease:

C. African sleeping sickness

An 18 year old man has fever, stiff neck, headache, and difficulty speaking; he rapidly passes into a coma. CSF shows no signs of bacterial or fungal infections by contains many lymphocytes. A brain biopsy is ordered, principally to confirm or rule out Herpes simplex virus (HSV) as the cause of illness. Why is it important to distinguish HSV encephalitis from that caused by other viruses?

Drugs exist for treatment of HSV encephalitis

A young man who had traveled extensively in Britain developed neurological disease and at autopsy Bovine spongiform encephalopathy (also known as 'Mad cow disease' and 'New-variant Creutzfeldt-Jakob disease') was confirmed. If the infectious agent were isolated from the patient's brain tissue, which phrase below would best describe it?

Enveloped virions with RNA genomes

What are the morphological forms of trypanosome brucei?

Epimastigote (in insect) and trypomastigote (in mammalian host)

True/False : The risk of acquiring Chagas disease while traveling is high

False - travelers are considered to have a low risk

Prion diseases infect nervous tissue and cause vacuolations in the tissue by:

Forcing the conformational change of normal PrPc to Prp sc

What are the modes of transmission for Chagas disease?

Getting someone else's parts, mommy-baby booby milk, eating contaminated food, working in bad places

Clostridium tetani are what type of bacteria?

Gram positive anaerobic spore-forming bacilli

What symptoms usually manifest during the first stages of African sleeping sickness?

Haemolytic phase - bouts of fever, headaches, joint pain, and itching

Where does multiplication of trypanosoma cruzi occur?

It multiplies in the tissue in the leishmanial form

What is the etiologic agent of PML - Progressive Multifocal Leukoencephalopathy?

JC-Virus

What symptoms do patients infected by African trypanosomiasis in the CNS stage of disease display?

Personality changes, shuffling gait, tremulous speech, mental retardation, cardiac failure

A 68 year old woman begins to suffer from motor and cognitive difficulties and, after seven months of progressive decline, dies. On the autopsy, in sections of brain tissue, there is prominent vacuolar degeneration of tissue and amyloid deposits, but no evidence of inflammation.

Progressive multifocal leukoencephalopathy (JC Virus)

A 12 year old boy comes to the pediatrician presenting with brassy cough, coryza, and conjunctivitis, fever, malaise, and photophobia. History of present illness reveals that a few days ago his mother found minute, whitish spots over the buccal / labial mucosa that rapidly increased in number and coalesced. Red, morbilliform, blanching rash. Labratory: Unsegmented ssRNA with a helical nucleocapsid on viral isolation in the tissue culture.

Rubella

What does trypanosome cruzi use as a vector?

Triatomidae (cone-nose bugs, bed bugs, "blood-sucking" bugs)

What are the resevoirs for West and East African trypanosomiasis

West - human, East - antelope and cattle

A 72 year old woman, a resident of Atlantic County, NJ, develops signs and symptoms of viral encephalitis. Serology confirms the pathogen as Eastern equine encephalitis virus. Which line in the table below correctly identifies the environmental reservoir and vector of this virus? Reservoir Vector

Wild Birds- mosquito

A 38 year old man came to the office with a chief complaint of jaw discomfort and inability to open his mouth fully for 3 days. He also said he had struck his right shin with a hammer 10 days earlier while attempting to fix his lawn mower. The hammer penetrated deeply through the skin, and although the wound hurt and bled, he had not sought medical attention. Seven days after the original insult, he started noticing jaw discomfort and the inability to open his mouth completely. On the 3rd day of this discomfort, his wife urged him to seek medical attention. The patient had no history of medical or surgical procedures, he had no known allergies, and was not taking medications. The diagnosis of this disease can only be made on clinical grounds. What is the diagnosis?

Wound tetanus

How would one acquire an infection with Trypanosoma cruzi?

being bitten by a kissing bug (genus Triatoma)