Exam 2 -- Infectious Disease Flashcards
Which disease in the US is the leading vector borne disease?
Lyme disease
True or false: for every case of Lyme disease reported, the CDC estimates that there is another case, unreported.
False; CDC estimates that there are 10 cases of Lyme for every one reported.
Name the gender prevalence, if any, for the following diseases, as discussed in class:
- Lyme
- West Nile Virus
- Syphilis
- Chlamydia
- Gonorrhea
- HIV/AIDS
- Toxoplasmosis
- Toxocariasis
- Lyme: none
- West Nile Virus: none
- Syphilis: male
- Chlamydia: female
- Gonorrhea: none
- HIV/AIDS: male? (63% of new HIV infections is MSM)
- Toxoplasmosis: none
- Toxocariasis: none
Name the age prevalence, if any, for the following diseases, as discussed in class:
- Lyme
- West Nile Virus
- Syphilis
- Chlamydia
- Gonorrhea
- HIV/AIDS
- Toxoplasmosis
- Toxocariasis
- Lyme: bimodal; 5-19 and 45-50
- West Nile Virus: none
- Syphilis: 20-30 for male and female
- Chlamydia: 20-30 for male, 15-25 for female
- Gonorrhea: 20-30 for male, 15-25 for female
- HIV/AIDS: 13-24? (26% of new HIV infections)
- Toxoplasmosis: none
- Toxocariasis: children? (up to 30% infected)
Jeopardy style:
95% of cases of Lyme disease in the US come from these geographic regions.
What are the Northeast, Wisconsin, and Minnesota?
Name both the spirochete which causes Lyme disease, as well as the organism that is its vector.
Borrelia burgdorferi is the spirochete, and the black legged tick (ixodes scapularis; in the east) and deer tick (ixodes pacificus; in the west) are the vector.
The ticks that transmit Lyme disease have three life stages after they hatch: larva, nymph, and adult. Which is the stage which most commonly affects human beings? What reasons were given in class for this?
Nymph; they’re smaller (less noticeable) than adults. They also outnumber adults 10:1, and they’re outside during spring and summer, which is when we are outside most.
The most common sign of the early/localized Lyme disease infection is erythema migrans (average of 7 days post bite). Which of the following descriptors usually apply to EM?
Painful
Itchy
Warm
For bonus points, what is the CDC definition of EM?
EM can feel warm, but typically involves no pain and no itch.
Bonus CDC definition of erythema migrans -at least 5 cm in size -expanding ->1 week in duration
If the early/localized form of Lyme disease is untreated, early disseminated infection can develop days to weeks after the bite. This stage can include more erythema migrans as well as the following three categories of symptoms:
- Rheumatoid
- Neurological
- Cardiac
What percentage of patients in the early disseminated form experience each of these categories? What specific symptoms occur in these stages?
Rheumatoid = 30%
-arthalgia with swelling
Neurological (15%)
- CN palsies (especially Bell’s palsy with a fever)
- meningitis
- acute febrile polyneuritis
Cardiac (1%)
- myopericarditis
- AV conduction defects or tachyarrythmias
Late disseminated Lyme disease occurs after 4 months on average. What symptoms occur in this stage?
Lyme arthritis (in 60% of patients) Chronic neurologic (in 5%) -Encephalopathy, low grade CNS inflammation, paresthesias, "stocking glove" pattern shooting pain
What ocular signs might occur in a patient with early Lyme disease?
Follicular conjunctivitis, episcleritis, perioribital edema
What ocular signs might occur in a patient with late Lyme disease?
Pupil abnormalities, CN palsies of III, IV, VI, pars planitis, choroiditis, granulomatous anterior uveitis, and unilateral or bilateral disc edema.
The CDC allows diagnosis of and treatment for Lyme disease based on their definition of EM and known exposure. Serological “two-tiered” testing is another way to try and diagnose this condition. Briefly describe two-tiered testing.
Start with an enzyme immunoassay (EIA) or an immunofluorescence assay (IFA). If negative, consider another diagnosis. If positive, continue to a Western Blot (for IgM and IgG if S/S less than 30 days, for IgG only if S/S for more than 30 days).
What sorts of conditions might cause two-tiered testing for Lyme disease to give false positives?
Autoimmune diseases, mono, malaria, syphilis, etc.
True or false: since two-tiered testing looks for antibodies, it can be used to determine success of treatment.
False; the organism can hide outside of the blood supply, so treatment success cannot be measured with serologic testing.
FYI: non-treponemal testing for syphilis is the only test discussed in class can be used to determine treatment success.
What treatments are used for early Lyme disease when the symptoms include EM, Carditis, Facial Nerve Palsy, or arthritis?
Oral doxycycline*, amoxicillin, or cefuroxime axetil for 14 days (28 days if arthritis)
Note: if patient is a child, no doxy
What treatments are used for early Lyme disease when the symptoms include meningitis or acute febrile polyneuritis?
IV Ceftriaxone or Penicillin G for 14 days (oral doxy for 28 days if allergic)
What treatments are used for late Lyme disease when the symptoms include arthritis?
Treat as in the early stage; if patient doesn’t respond, retreat with another 28 day course of oral meds or switch to IV ceftriaxone for 14-28 days. If still no response, treat with anti-inflammatories (NSAIDs, corticosteroids, DMARDs).
What treatments are used for the neurological symptoms of late Lyme disease?
IV ceftriaxone for 14-28 days
Post-treatment Lyme disease is a very serious condition that features continuing pain, sleep disturbance, and cognitive dysfunction. It occurs in 10-20% of patients with Lyme disease.
Free card.
True or false: although spraying clothes with permethrine and >20% DEET are among some of the most effective things you can do to reduce your chances of being bitten by a tick, the overall best thing you can do is sit down with the ticks, make friends, and sing kumbaya.
False (well, the last part at least).
How is West Nile Virus transmitted to humans?
Typically through mosquitoes (they bite infected birds then pass it on to humans), though it can occur through blood transfusions or organ transplantations, breast milk, transplacentally.
There is an incubation period typically of 2-6 days for West Nile Virus before symptoms start to appear. What type of non-ocular symptoms are there? How many people infected with WNV experience these symptoms?
Only 20%; it’s known as West Nile Fever at this stage. Early symptoms include flu-like symptoms, rash on trunk.
Although the ocular symptoms of West Nile Fever occur less commonly, they generally last longer than the non-ocular symptoms (2-3 weeks compared to about 1 week). What ocular signs/symptoms are there?
Conjunctivitis, photophobia, eye pain, floaters, vasculitis. May notice a linear pattern on the retina due to choroiditis.
What percentage of patients who are infected with WNV develop the neuroinvasive form? What symptoms can occur in this stage?
Less than 1%; symptoms may include meningitis, encephalitis, acute flaccid paralysis, and rarely optic neuritis or CN abnormalities.
What two findings were discussed in class that should make WNV rise to the top of your list of possible diagnoses?
Linear choroidal pattern on the retina and paralysis plus muscle weakness.
True or false: the neurologic effects of neuroinvasive WNV are usually short-lived.
False; they can be permanent, or last a very long time.
What is the overall fatality rate for patients who develop neuroinvasive WNV? Is it higher or lower in meningitis as compared to encephalitis?
10% is the overall, and it is higher in encephalitis than in meningitis.
Late manifestations of WNV occur months to more than a year after the diagnosis of WNV. What percentage of patients infected with WNV will develop late manifestations? List some of the manifestations.
About 50%; symptoms include fatigue/malaise/weakness (in 49% of these patients), memory problems, HA, depression (in 24%), and new tremor (in 20%).
What factors are taken into account when considering WNV as a diagnosis?
Symptoms consistent with the disease, having visited or lived in a high risk state.
If you have a patient and you suspect they have meningitis or encephalitis due to WNV, what lab screening tests could you send for? What situations may cause false positives?
Antibody tests (EIA, IFA, Western Blot) looking for IgM in the serum or the CSF (CSF preferred, since IgM in the CSF indicates presence of the virus in the CSF too). St. Louis encephalitis virus or yellow fever vaccination can cause false positives.
If your patient tested positive for WNV on a screening test, what confirmatory tests could you run?
Plaque reduction neutralization test (take live WNV, add to a sample of the patient’s serum–positive if no growth, negative if growth) – this is the gold standard to differentiate WNV from St. Louis encephalitis virus
RT-PCR (detects viral RNA–positive confirmed the infection, negative does not rule out the infection)
Unfortunately, there is no specific treatment for WNV, there are only supportive therapies. What can you do to help the patient?
Pain control, IV fluids (due to N&V), respiratory support (from the flaccid paralysis), antibiotics (prevent secondary infections), anti-inflammatory meds, osmotic agents (decrease ICP caused by brain swelling).
Protective measures against mosquitoes is very similar to those against ticks. What additional things could you do to protect against mosquitoes?
Don’t go outside at dawn and dusk (this is when they most commonly feed) and drain any standing water (this is where they lay their eggs).
True or false: there are an estimates 20 million new STIs each year in the US, with about half of them occurring in the age range of 20-30
Half true–there are indeed 20 million new STIs each year in the US, but half of them occur in the 15-24 age range.
STDs are a major cause of infertility in women in the US. Which STD discussed in class is the main concern for female infertility?
Chlamydia.
It is estimated that only 50% of individuals get recommended screening for STIs. What is the chlamydia screening recommendation for non-pregnant women?
Annual chlamydia screening if:
-Sexually active
AND
-25 and under
OR
-Older
AND
-New or multiple sex partners
It is estimated that only 50% of individuals get recommended screening for STIs. What is the gonorrhea screening recommendation for non-pregnant women?
Annual gonorrhea screening if:
-Sexually active
AND
-New or multiple sex partners/Those living in communities with high burden of disease
It is estimated that only 50% of individuals get recommended screening for STIs. What is the screening recommendation for pregnant women?
Syphilis/HIV/Chlamydia/HBV screening if:
-Pregnant
Gonorrhea screening at first prenatal visit if:
-At-risk and pregnant
It is estimated that only 50% of individuals get recommended screening for STIs. What is the screening recommendation for men?
Annual syphilis/chlamydia/gonorrhea/HIV screening if:
-Sexually active gay, bisexual, or other MSM
If multiple/anonymous partners, screen every 3-6 months.
If illicit drug user (or if partner is), screen even more frequently.
Syphilis incidence peaked in 1946, then had a huge decrease by 1956 due to what treatment?
Penicillin
Though the incidence of syphilis decreased steadily in the latter half of the 20th century, there was a dramatic rise from 1986-1990. What caused this increase?
HIV, birth control pills, drug culture
True or false: although there is a higher rate of syphilis among men as compared to women, the difference is minimal.
False; the rate of syphilis among men is more than 10x that in females.
What is the name of the organism that causes syphilis? About what ratio of exposed individuals will acquire the organism?
Treponema pallidum; about 1/3 exposed individuals acquire the organism.
Treponema pallidum can enter intact mucous membranes.
Free card.
Syphilis is hard to diagnose partly because of the fact that the disease has episodes of activity and periods of latency. About how long is the average incubation period (time from initial infection to symptoms)?
3 weeks
There are four classic stages to syphilis. What are the signs/symptoms of primary syphilis?
Regional lymphadenopathy (caused by immune response in the location of first exposure), and chancre (due to local infiltration of PMNs, also in the area of first exposure)
Describe the chancre found in primary syphilis.
It starts 2-6 weeks after exposure, as a red painless papule (0.5-1.5 cm in size). It ulcerates “cleanly” in 1-2 days, then heals in 3-6 weeks.
True or false: though most untreated individuals with primary syphilis will progress to secondary, there are a few whose genetic make up seem to protect them from progression to secondary.
False; 100% of untreated individuals with primary will progress to secondary.
In which gender is secondary syphilis more likely, and why?
Females; the ulcers that occur in primary syphilis are more likely to be noticed by men, which means men are more likely to be treated for primary syphilis than are women.
What are the non-ocular signs and symptoms of secondary syphilis?
Cutaneous lesions (rash on trunk/extremeties), mucous membrane lesions (small superficial ulcerated areas), condylomata lata (moist, wart-like papules in warm intertriginous [skin-on-skin] areas), alopecia (including eyebrows, eyelashes, and facial hair), and flu-like symptoms.
The cutaneous lesions of secondary syphilis are most obvious on the palms, hands, and soles of feet and DO NOT ITCH. Which other disease discussed in class features a maculopapular rash that SPARES the palms and soles? Which features a rash that DOES itch?
Acquired toxoplasmosis spares the palms and soles.
HIV can feature an itchy rash.
What are the ocular signs and symptoms of secondary syphilis?
Madarosis, iris nodules, disc edema, exudative RD, plus just about any type of “itis” you can think of.
If untreated, secondary syphilis lasts for about 4-8 weeks before the patient becomes symptom-free and enters the latent period, which consists of an early period and a late period. Classify each of the following bullet points as “early” or “late” according to which portion of the latent period it pertains to.
- Patient still sexually infectious
- Organism can be passed by mother to fetus
- Within one year of infection (or relapse)
- Not considered sexually infectious
- Relapse is rare
- More than one year after infection (or relapse)
- 25% of these patients relapse to secondary
- Patient still sexually infectious: early
- Organism can be passed by mother to fetus: early AND late
- Within one year of infection (or relapse): early
- Not considered sexually infectious: late
- Relapse is rare: late
- More than one year after infection (or relapse): late
- 25% of these patients relapse to secondary: early
What two categories of symptoms occur in tertiary syphilis? How long after initial infection does each occur?
Benign (10-15 years post infection): gummas (localized soft granulomas), chronic inflammation, fibrosis of tissue/destruction of cartilage.
Cardiovascular (20-30 years post infection): aortic aneurysm, aortic valve insufficiency/regurgitation, CAD, MI, HF, strokes, seizures.
What causes the cadiovascular symptoms of tertiary syphilis?
Damage caused by immune process causes cellular debris to be released into the blood. Antibodies known as reagin tag a cardiolipin-cholesterol-phospholipid antigen made from the debris. The immune system targets these antigens and causes inflammation and even more damage to heart tissue.
In early neurosyphilis, what symptoms are possible? About how long after infection does early neurosyphilis tend to occur?
CN involvement (all but CN V; also, Bell’s palsy could be accompanied by a fever), meningitis, strokes/seizures, tingling/weakness of legs, loss of vibratory sense, auditory/ophthalmic involvement.
Occurs within one year of infection.
About how long after infection does late neurosyphilis tend to occur?
10-30 years
In late neurosyphilis, symptoms can be motor-based or sensory-based. Which motor symptoms are possible?
Acronym PARESIS
Personality disturbances Affect abnormalities Reflex hyperactivity Eye abnormality Sensorium changes Intellectual impairment Slurred speech
In late neurosyphilis, symptoms can be motor-based or sensory-based. Which sensory symptoms are possible?
Acronym OD LUAU
Optic atrophy Decreased peripheral reflexes Lightning pains in extremeties Unusual gait Argyll-Robertson pupil Urinary and fecal incontinence
Syphilis can cause stillbirth or miscarriage. What are the chances of syphilis transmitting to the fetus if the mother is in the primary or secondary stage? Early latent? Late latent?
Primary/secondary: 100%
Early latent: 40%
Late latent: 10%
Early congenital syphilis has manifestations prior to age two. What manifestations can occur?
Mucocutaneous lesions like those in secondary syphilis, as well as a bilateral rash with vesicles on the palms and feet, and inflammation of cartilage and bone (very painful, child may not move much).
Late congenital syphilis has manifestations between ages five and twenty. What manifestations can occur?
Hutchinson triad (defective adult teeth, interstitial keratitis, deafness), poorly formed bones, neurosyphilis possible.
Serological testing for syphilis falls into the category of non-treponemal and treponemal. Categorize each of the following bullet points according to which type of test it pertains to.
- Less expensive
- Targets reagin
- Cannot be used to check success of treatment
- Qualitative and quantitative
- Most common test is FTA-ABS
- More expensive
- Qualitative only
- Targets antibody against T. pallidum
- Can be used to check success of treatment
- Most common tests are VDRL and RPR
Non-treponemal
- Less expensive
- Targets reagin
- Qualitative and quantitative
- Can be used to check success of treatment
- Most common tests are VDRL and RPR
Treponemal
- More expensive
- Targets antibody against T. pallidum
- Qualitative only
- Cannot be used to check success of treatment
- Most common test is FTA-ABS
What are the advantages of non-treponemal serological testing for syphilis?
Rapid and inexpensive, easy to perform, quantitative and qualitative, can be used to monitor success of treatment, as well as evaluate for possible reinfection.
