Internal Medicine INFECTIOUS DISEASE Flashcards
Infectious Disease (144 cards)
0
Q
Etiology of HIV: HIV is transmitted through
A
- Injection of drug use with contaminated needle
- Sex, men who have sex with men
- Transfusion
- Perinatal
- Needle stick
1
Q
What is HIV?
A
Is retrovirus infect infecting CD4 (T-helper) cell. CD4 cells drop from normal level of 600 to 1000 per μL at a rate of 50 to 100 per year in a person who is untreated. Take about 5-10 yr before clinical manifestations occur. CD4 count leads to opportunistic infections that lead to illness.
2
Q
Mode of transmission
A
- Vaginal Transmission
- Oral Sex
- Needle stick injury
- Anal sex
- Mother to child
3
Q
HIV pt are encourage not to eat
A
Raw meat or eggs to avoid toxoplasma, pseudomonas, campylobacter, and salmonella as a 2º prevention measure.
4
Q
Infections occurs with profound immunosuppression when CD4 is below________.
A
200μL
5
Q
Infection occurs with above 200μL
A
Varicella zoster (shingles) Herpes simplex Tuberculosis Oral and vaginal candidiasis Bacterial pneumonia
6
Q
Initial infection of HIV is often asymptomatic, but pt patients may but patients may also present
with mononucleosis-like or flulike symptoms that includes
A
fever, lymphadenopathy, maculopapular rash, pharyngitis, diarrhea, nausea/vomiting, weight
loss, headache.
7
Q
Maculopapular Rash
A
.
8
Q
HIV may later present as
A
night sweats, weight loss, thrush, recurrent infections, or opportunistic infections.
9
Q
What is the best initial test for HIV?
A
ELISA
10
Q
What is the confirmatory test for HIV?
A
Western blot testing
11
Q
How long does it take anti-HIV antibodies to show in the blood stream?
A
6 months to appear after exposure.
12
Q
What are some baseline evaluation for HIV?
A
HIV RNA PCR (viral load), CD4+ cell count, CXR, PPD skin testing, Pap smear, VDRL/RPR, and serologies for CMV, hepatitis, toxoplasmosis, and VZV.
13
Q
What is the strongest indication for antiretroviral medication is
A
- CD4 below 350μL*
* Symptomatic pt*
14
Q
What is the best initial antiretroviral drug ?
A
Atripla, which is a combination of three medication (emtricitabine, tenofovir, and efavirenz). Alternate Drug Regimen: Base on a combination of 3 drugs from at least 2 different classes.
Ganciclovir used for those with eye problem.
15
Q
What is the most important principle when selecting multiple medication?
A
Do a viral resistance testing This decrease the likehood of starting medication to which the patient’s virus is resistant.
16
Q
HIV pregnant woman. If the patient is not on antiretroviral therapy at the time of delivery, she should be treated with
……..
A
Zidovudine (AZT) intrapartum.
Infants should receive AZT for six weeks after birth.
17
Q
Candidiasis
A
Commonly called “yeast infection” or “thrush,” candidiasis can be caused
by any Candida species but is most commonly caused by C. albicans.
In immune-competent patients, it typically presents as a superficial infection of the skin or mucous membranes in moist areas such as skin folds, armpits, the vagina, and below the breasts. Oral thrush is not uncommon among children, but in adults it is often a sign of a weakened immune system.
18
Q
History & PE with pt with Candidiasis
A
Patients often have a history of antibiotic use, steroid use, or diabetes.
19
Q
What are some symptoms of Candidiasis?
A
Oral candidiasis: Presents with painless white plaques that cannot easily be scraped off.
■ Candidiasis of the skin: Presents as pink, circular, erythematous macules
that converge, with smaller satellite lesions seen nearby, often in
skin folds.
■ In infants, infection can often be seen in the diaper area and along the inguinal
folds.
20
Q
Diagnosis of Candidiasis
A
Confirmed by KOH preparation of a scraping or swab of the affected area.
KOH dissolves the skin cells but leaves the Candida untouched such that candidal hyphae and pseudospores become visible.
21
Q
Treatment of candidiasis
A
Oral candidiasis: Oral fluconazole; nystatin swish and swallow.
■ Superficial (skin) candidiasis: Topical anti-fungals; keep skin clean and dry.
■ Diaper rash: Topical nystatin.
22
Q
What organism cause meningoencephalitis in AIDS patients?
A
Cryptococcus Neoformans; Microscopic examination of the CSF prepared with India ink reveals budding yeasts with prominent capsules.
23
Q
Cryptococcosis
A
.
24
Histoplasmosis
is a dimorphic fungus that remains in a mycelial form at ambient temperatures and grows as yeast at body temperature in mammals. (also known as "Cave disease,"[1] "Darling's disease,"[1] "Ohio valley disease,"[1]. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Flulike illness. *Associated with bird and bat droppings*
25
Physical exam with pt with Histoplasmosis
Fever, weight loss, hepatosplenomegaly, lymphadenopathy, nonproductive
cough, and pancytopenia indicate disseminated infection (most often within 14 days).
26
How do you diagnosis Histoplasmosis?
CXR shows diffuse nodular densities, focal infiltrate, cavity, or hilar lymphadenopathy (chronic infection is usually cavitary).
27
What is the most sensitive test for making the initial diagnosing Histoplasmosis?
*urine and serum polysaccharide antigen test*
28
Other diagnosis of Histoplasmosis
The yeast form is seen with silver stain on biopsy.
29
Treatment for Histoplasmosis
Mild pulmonary disease or stable nodules: *Itraconazole*
■ Chronic cavitary lesions: Give itraconazole for > 1 year.
■ Severe acute pulmonary disease or disseminated disease: *Amphotericin B* or amphotericin B liposomal × 3-10 days followed by itraconazole × 12
weeks or longer. Maintenance therapy with daily *itraconazole*.
30
Pneumocystis jiroveci Pneumonia
Formerly known as Pneumocystis carinii pneumonia, or PCP. Risk factors include impaired cellular immunity and AIDS.
31
History and physical exam of pt with Pneumocystis jiroveci Pneumonia
dyspnea on exertion, fever, *nonproductive cough* (dry), tachypnea, weight loss, fatigue, and impaired oxygenation.
32
Diagnosis of Pneumocystis jiroveci Pneumonia
Cytology of induced sputum or bronchoscopy specimen with
silver stain and immunofluorescence. Obtain an ABG to check PaO2.
■ CXR may show diffuse, bilateral interstitial infiltrates with a ground-glass appearance, but any presentation is possible.
LDH are alway elevated
33
LDH
(Lactate Dehydrogenase) increased with MI, liver disease and metastatic CA. DH is most often measured to check for tissue damage. The protein LDH is in many body tissues, especially the heart, liver, kidney, muscles, brain, blood cells, and lungs.
34
What is the most likely disgnosis with an AIDS pt presenting dyspnea on exertion, dry cough, and fever. Pt has a low CD4 count (200μL)
Pneumocystis jiroveci Pneumonia
35
What is the best initial test for Pneumocystis jiroveci Pneumonia?
CXR
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The most accurate test for Pneumocystis jiroveci Pneumonia?
Bronchoalveolar lavage
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What is the best initial treatment for Pneumocystis jiroveci Pneumonia?
```
Trimethoprim/Sulfamethoxazole (TMP-SMX).
Add steroid (such as prednisone) for severe case (PaO2<70 or arterial alveolar oxygen gradient >35)
```
38
Botulism
A type of food poisoning caused by the production of the bacteria Clostridium botulinum in improperly canned foods. It is characterized by vomiting, abdominal pain, difficulty seeing, dryness of the mouth and pharynx, dyspepsia, cough; it often results in death. Nausea, Diplopia, Dilated/fixed pupils Extremely dry mouth unrelieved by drinking fluids.
39
What is botulism?
Botulism is an acute neurologic disorder that causes potentially life-threatening neuroparalysis due to a neurotoxin produced by Clostridium botulinum.
40
Mothers are encouraged not to give infants *Honey* to avoid
Clostridium botulinum bc this organism can cause GI toxins
41
Clostridium botulinum
cause paralysis by blocking acetylcholine from binding with motor neurons, resulting in a descending flaccid paralysis. Ingestion or inhalation of preformed toxin is the most likely method of biowarfare with botulinum toxin. It is not transmissible to person to person; therefore, patients do not need isolation.
42
Clostridium botulinum diagnosis
is based on clinical finding. *GI problem with loss of muscle strength, tone, and reflex*
43
Clostridium botulinum Tx
antitoxin. because clinicial features result from toxin exposure and not from infection with C. botulinum
44
Chlamydia Trachomatis
Most common bacterial STD in the United States. Gonococcal infections are the second.
45
What does Chlamydia Trachomatis infect?
genital tract, urethra, anus, and eye.
46
What organism coexist with with Chlamydia?
N. gonorrhoeae
47
Mucopurulent cervicitis
____________ produces purulent yellow drainage from the cervical os, usually as a result of infection from Chlamydia, gonorrhea, or herpes. May present without sx.
48
What does the physical exam reveal with Pt with Chlamydia?
urethritis, mucopurulent cervicitis, or PID.
| ■ Exam may reveal cervical/adnexal tenderness in women or penile discharge and *testicular tenderness in men*.
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What is the gold standard for Chlamydia & Gonorrhea?
*Culture and gram stain*. Gonorrhea Nucleic acid amplification tests can be sent on penile/vaginal tissue or from urine.
50
Key Fact of Chlamydia
Chlamydia species cause arthritis, neonatal conjunctivitis, pneumonia, nongonococcal urethritis/
PID, and lymphogranuloma venereum.
51
Key Fact of Chlamydia
Chlamydia infection is a common cause of nongonococcal urethritis in men.
52
Chlamydia tx
Doxycycline 100 mg PO BID × 7 days or azithromycin 1 g PO × 1 day. Use
erythromycin in pregnant patients.
53
Gonorrhea Tx
Ceftriaxone IM or cefepime PO × 1 dose. Also treat for presumptive chlamydia coinfection
54
Physical exam of Gonorrhea
Presents with a *greenish-yellow discharge*, pelvic or *adnexal pain*, and swollen Bartholin's glands. Men experience a *purulent urethral discharge*, dysuria, and erythema of the urethral meatus.
55
Cholera (acute) causes diarrhea, which is define as
the production of > 200 g of feces per day along with ↑ frequency or ↓ consistency of stool. *Rice water diarrhea*
-*Acquired through eating raw oysters*
56
Cholera diagnosis
Acute diarrhea usually does not require laboratory investigation unless the patient has a high fever, bloody diarrhea, or diarrhea lasting > 4-5 days.
57
What is the best tx for cholera?
When bacterial infection is not suspected, treat with antidiarrheals
(e.g., loperamide, bismuth salicylate) and *oral rehydration solutions*.
58
Diphtheria
Diphtheria manifests as either an upper respiratory tract or cutaneous infection and is caused by the aerobic gram-positive bacteria, Corynebacterium diphtheria. An adherent, dense, grey pseudomembrane covering the tonsils is classically seen in diphtheria (pix)
59
Diagnosis of C. Diphtheriae
diagnosis of C diphtheriae, it is vital to both isolate C diphtheriae in culture media and to identify the presence of toxin production
60
Tx for Diphtheria
obtaining antitoxin
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Patients with diphtheria may present with the following complaints:
- Low-grade fever (rarely >103°F) (50-85%) and chills
- Malaise, weakness, prostration
- Sore throat (85-90%)
- Headache
- Cervical lymphadenopathy and respiratory tract pseudomembrane formation (about 50%)
- Serosanguineous or seropurulent nasal discharge, white nasal membrane
- Hoarseness, dysphagia (26-40%)
- Dyspnea, respiratory stridor, wheezing, cough
62
Salmonellosis
Salmonellae are gram-negative motile bacilli. As with the closely related bacterium Escherichia coli, salmonellae are potential enteric pathogens and a leading cause of bacterial foodborne illness. *Animal carriers of salmonella: turtles, cattle, pigs, sheep, poultry*
63
Salmonellosis History
Ingestion of contaminated beef, poultry or eggs. Affects young children and elderly patients. Generally lasts 2-5 days. Also found in contaminated water.
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Salmonellosis exam
Prodromal headache, fever, myalgia, abdominal pain. Fecal WBCs, loose stool, and no bloody stool.
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Salmonellosis Tx
Ciprofloxacin
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Shigellosis
Bacteria, Bloody Diarrhea, Abdominal pain and cramps, Fever. A child in daycare has very watery diarrhea with blood mucus and PMNs in stool, with cramps and fever
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Shigellosis
```
Acute bloody diarrhea[5]
Crampy abdominal pain
Tenesmus
Passage of mucus
Fever (1-3 d after exposure)
Occasionally vomiting (35% prevalence)
Self-limited course (3 d to 1 wk and rarely lasts as long as 1 mo)
Physical
Lower abdominal tenderness
Normal or increased bowel sounds
Dehydration (occasional)
```
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How do you diagnosis Shigella?
Fecal leukocytes and erythrocytes
69
Shigella
May lead to severe dehydration.
| Can also cause febrile seizures in the very young.
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Shigella tx
Ceftriaxone, Ciprofloxacin
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Tetanus
Tetanus is an illness characterized by an acute onset of hypertonia, painful muscular contractions (usually of the muscles of the jaw and neck), and generalized muscle spasms without other apparent medical causes. "lockjaw"
72
Tetanus Physical examination
Common first signs of tetanus are headache and *muscular stiffness in the jaw (ie, lockjaw)*, followed by neck stiffness, difficulty swallowing, rigidity of abdominal muscles, spasms, and sweating. Patients often are afebrile. Stimulation of the posterior pharyngeal wall may elicit reflex spasms of the masseter muscles that cause patients to bite down as opposed to gag (spatula test).[13]
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Tetanus Initial Supportive Therapy and Wound Care
Prophylactic intubation should be seriously considered in all patients with moderate-to-severe clinical manifestations. Intubation and ventilation are required in 67% of patients
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Tetanus tx
Doxycycline and Metronidazole
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Pertussis
cause by gram "-" bacteria Bordetella pertussis
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Pertussis vaccine
The DTaP vaccine (given in five doses in early childhood) is protective, but immunity wanes by adolescence
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Pertussis information
Adolescents and young adults serve as the primary reservoir for pertussis. Pertussis can be life threatening for
young infants but is generally a milder infection in older children and adults.
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Pertussis History
Has three stages: (1) catarrhal (mild URI symptoms; lasts 1-2 weeks), (2) paroxysmal (paroxysms of *cough with inspiratory whoop* and post-tussive emesis; lasts 2-3 months), and (3) convalescent (symptoms wane).
■ Patients most often present in the paroxysmal stage but are most contagious in the catarrhal stage.
■ The classic presentation is an infant < 6 months of age with post-tussive emesis and apnea.
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What is the diagnosis of pertussis?
Labs show an elevated WBC count with lymphocytosis (often ≥ 70%).
■ *Culture is the gold standard*.
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Pertussis Tx
*Erythromycin*: Azithromycin
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Tuberculosis
Infection due to Mycobacterium tuberculosis. Initial infection usually leads to latent TB infection (LTBI) that is asymptomatic. Most symptomatic cases (i.e., cases of active disease) are due to reactivation of latent infection rather than to 1° exposure. Pulmonary TB is most common, but disseminated or extrapulmonary TB should be considered as well.
■ TB can infect almost any organ system, including the lungs, CNS, GU tract, bone, and GI tract.
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Tuberculosis risk factor
Risk factors for active disease (i.e., reactivation) include immunosuppression (HIV), alcoholism, preexisting lung disease, diabetes, and advancing age. Risk factors for TB exposure include homelessness and crowded living conditions (e.g., prison), immigration/travel from developing nations, working in an allied health profession, and interacting with known TB contacts.
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Tuberculosis physical exam
Presents with cough, *hemoptysis*, dyspnea, *weight loss, fatigue, night sweats*, fever, cachexia, hypoxia, tachycardia, lymphadenopathy, an abnormal lung exam, and a prolonged (> 3-week) symptom duration. TB is a common cause
of fever of unknown origin (FUO). HIV patients can present with atypical
signs and symptoms and have higher rates of extrapulmonary TB.
84
What is the best diagnostic test Tuberculosis?
Acid fast stain and culture on 3 high volume lumbar punctures. Acid-fast bacilli (AFB) smear and culture - Using sputum obtained from the patient
85
Tuberculosis tx
*Prophylaxis: Isoniazid chemoprophylaxis*
Active TB: Directly observed multidrug therapy with a four-drug regimen
(INH, pyrazinamide, rifampin, ethambutol) × 2 months, followed by
four months with INH and rifampin.
■ Administer vitamin B6 (pyridoxine) with INH to prevent peripheral neuritis.
■ Latent TB: For conversion of PPD without signs/symptoms of active disease,
initiate therapy with INH × 9 months. Alternative regimens include
INH × 6 months or rifampin × 4 months
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Pt with TB are RIPE for tx
.
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Parasitic Infections: LICE
Lice live off blood and on specific parts of the body, depending on their species. The head louse lives on the scalp and lays its eggs as nits attached to hair; the body louse lives in clothing and bites only the body. The pubic louse lives on pubic hair. Lice are spread through body contact or by the sharing of bedclothes and other garments. They secrete local toxins that lead to pruritus.
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Parasitic Infections: LICE Physical exam
Patients with lice often experience severe pruritus, and 2° bacterial infection of the excoriations is a risk. Classroom epidemics of head lice are common.
■ Body lice are seen in people with inadequate hygiene or in those with crowded living conditions. Pubic lice (called "crabs" because of their squat, crablike body shape) contain anticoagulant in their saliva, so their bites often turn blue.
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Parasitic Infections: LICE Diagnosis
Lice can be seen on hairs or in clothes.
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Parasitic Infections: LICE treatment
Hint "Get rid of lice with RID"
Head lice: Treat with OTC pyrethrin (RID) and mechanical removal of nits.
■ Body lice: Wash body, clothes, and bedding thoroughly. Treating the body with topical permethrin or pyrethrin may also be required.
■ Pubic lice: Treat with RID.
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Parasitic Infections: Scabies
Caused by Sarcoptes scabiei, a tiny arthropod that mates on the skin surface, after which the female digs a passage into the stratum corneum and lays her eggs. The burrowing leads to pruritus that ↑ in intensity once an allergy to the mite or its products develops. Scabies mites are spread through close contact.
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Parasitic Infections: Scabies History
Patients present with intense pruritus, especially at *night and after hot showers*.
■ The most commonly affected sites are the hands, axillae, and genitals.
■ On exam, the mite's *track* can sometimes be seen along with *erythematous, excoriated papules. 2°* bacterial infection is common.
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Parasitic Infections: Scabies Diagnosis
A history of pruritus in several family members is suggestive. The mite may be identifiable by scraping an intact tunnel and looking under the microscope, but this is often difficult.
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Parasitic Infections: Scabies Tx
Patients should be treated overnight with 1-2 applications of 5% *permethrin from the neck down*, and their contacts should be treated as well. Oral ivermectin is also effective. Pruritus may persist for two weeks after treatment, so symptomatic treatment should be provided.
95
Toxoplasmosis
Risk factors include ingesting raw or undercooked meat and changing cat litter (feces). Worldwide, exposure is highest in France.
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Toxoplasmosis History/ Physical Exam
■ 1° infection is usually asymptomatic.
■ Reactivated toxoplasmosis occurs in immunosuppressed patients and may present in specific organs (brain, lung, and eye > heart, skin, GI tract, and liver).
■ *Encephalitis is common in seropositive AIDS patients. Classically, CNS lesions present with fever, headache, altered mental status, seizures, and focal neurologic deficits.*
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Toxoplasmosis Diagnosis
*Best initial test is elevated IgM to toxoplasma; most accurate test is PCR for toxoplasmosis*
Serology, PCR (indicates exposure and risk for reactivation); tissue examination for histology, isolation of the organism in mice, or tissue culture.
■ In the setting of CNS involvement, obtain a CT scan *(can show multiple isodense or hypodense, ring-enhancing mass lesions)* or an MRI (predilection for basal ganglia; more sensitive).
98
Toxoplasmosis tx
pyrimethamine + sulfadiazine
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Rocky mountain spotted fever
A disease caused by *Rickettsia rickettsii* and carried by the American dog tick (Dermacentor variabilis). The organism invades the endothelial lining of capillaries and causes small vessel vasculitis.
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Rocky mountain spotted fever Hx/PE
Presents with headache, fever, malaise, and rash. The characteristic rash is initially macular (beginning on the *wrists and ankles*) but
becomes petechial/purpuric as it spreads centrally (see next slide for picture). Altered mental status or DIC may develop in severe cases.
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Rocky mountain spotted fever Pix
.
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Rocky mountain spotted fever Dx
Clinical diagnosis should be confirmed with indirect immunofluorescence of rash biopsy.
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Rocky mountain spotted fever Tx
Doxycycline
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Rocky mountain spotted fever
Rocky Mountain spotted fever starts on the wrists and ankles and then spreads centrally.
105
Syphilis
Caused by Treponema pallidum, a spirochete. AIDS can accelerate the course of disease progression.
106
Syphilis History/PE 1st degree (10-90 days)
Presents with a *painless ulcer*. Chancre is a painless ulceration (sore).
107
Syphilis History/PE 2nd degree (4-8 weeks after chancre)
Presents with low-grade fever, headache, malaise, and generalized lymphadenopathy with a diffuse, symmetric, asymptomatic
(nonpruritic) *maculopapular rash on the soles and palms*.
Highly infective 2° eruptions include mucous patches or condylomata lata (See picture)
108
Syphilis History/PE 3rd degree (1-20 years after initial infection)
Presents with destructive, granulomatous gummas. Neurosyphilis includes tabes dorsalis (posterior column degeneration), meningitis, and Argyll Robertson pupil (constricts with accommodation but not reactive to light). Cardiovascular findings include dilated aortic root, aortitis, aortic root aneurysms, and aortic regurgitation.
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What is the best initial test for Syphilis?
*+RPR, VDRL* false "+s". Most accurate test is FTA ABS or dark field microscopy
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Syphilis Tx
Benzathine penicillin IM
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Cytomegalovirus
Most 1° CMV infections are asymptomatic; serious reactivation generally occurs only in immunocompromised patients. Seventy percent of adults in the United States have been infected. Transmission occurs via sexual contact, in breast milk, via respiratory droplets in nursery or day care facilities, and through blood transfusions. Risk factors for reactivation include the first 100 days status post tissue or bone marrow transplant and HIV positivity with a CD4+ < 100 or a viral load > 10,000.
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Cytomegalovirus history /PE
Systemic infection may resemble EBV mononucleosis-CMV retinitis: Has a high rate of retinal detachment ("pizza pie" retinopathy)
- GI and hepatobiliary involvement.
- CMV pneumonitis: Presents with cough, fever, and sparse sputum production; associated with a high mortality rate.
- CNS involvement: Can include *polyradiculopathy, transverse myelitis, and subacute encephalitis*
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Cytomegalovirus Diagnostic test
Urine or saliva viral titers. Most accurate test is urine or saliva PCR for viral DNA.
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Cytomegalovirus tx
Ganciclovir
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Epstein-Barr infection
a herpes virus that can lead to infectious mononucleosis. Most commonly occurs in young adult patients; usually due to acute EBV infection. Transmission most often occurs through exchange of body fluids, including saliva.
116
Epstein-Barr infection clinical symptoms
Symptoms of infectious mononucleosis are *fever, sore throat, and swollen lymph glands*. Exam may reveal low-grade fever, generalized lymphadenopathy (especially posterior cervical), tonsillar exudate and enlargement, palatal petechiae, a generalized maculopapular
rash, splenomegaly, and bilateral upper eyelid edema.
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Epstein-Barr infection Dx
- Diagnosed by the *heterophil antibody* (Monospot) test.
| - EBV-specific antibodies
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Epstein-Barr infection
...
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Herpes simplex infection
HSV-1 usually produces oral-labial lesions, whereas HSV-2 usually causes genital lesions. The virus spreads through epidermal cells, causing them to fuse into giant cells
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Herpes simplex infection
The initial infection is passed by direct contact, after which the herpesvirus remains dormant in local nerve ganglia.
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Herpes simplex infection HSV-1
Recurrent oral herpes (HSV-1): Typically consists of the common "cold sore," which presents as a cluster of crusted *vesicles* on an erythematous base (see pix). It is often triggered by sun and fever.
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Herpes simplex infection HSV-2
Recurrent genital herpes (HSV-2): Unilateral and characterized by a cluster of blisters on an erythematous base, but with less pain and systemic
involvement than the 1° infection.
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Herpes simplex infection Dx
Diagnosed primarily by the clinical picture. *Multi-nucleated giant cells
on Tzanck smear*
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Herpes simplex infection Tx
Oral or IV acyclovir
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Influenza
A highly contagious orthomyxovirus transmitted by droplet nuclei. There three types of influenza: A, B, and C. Subtypes of influenza A (e.g., H5N1, H1N1) are classified on the basis of glycoproteins
126
Influenza presents with
Fevers, myalgias, chills, cough,
| coryza, and weakness, HA, sore throat, N/V, diarrhea
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Influenza Dx
Leukopenia is a common finding. Rapid influenza tests of viral antigens from *nasopharyngeal swabs* are available. More definitive diagnosis can be made with *DFA tests or viral culture*.
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Influenza Tx
Symptomatic care with analgesics and cough medicine. Antivirals such as oseltamivir or zanamivir are most effective when used within two days of onset and may shorten the course of infection by 1-2 days.
129
Rabies
Rabies is a viral disease that affects the central nervous system (CNS). The virus is transmitted in saliva or in aerosolized secretions from infected animals, typically via a bite. The virus is not hardy and is quickly inactivated by drying, ultraviolet rays, x-rays, trypsin, detergents, and ether.
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Rabie exposure
Dogs, cats, ferrets, skunks, racoon, bats
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Rabies Tx
No specific treatment against rabies disease is available. Mechanical ventilation and oxygen therapy should be started. *Rabies vaccine immunoglobulin* is given along with monoclonal antibodies, ribaviron, interferon-, and ketamine. It is almost universally fatal within 7 days, most likely from respiratory failure. *The only viral infection that is prevented by vaccination.*
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Rabies Dx
PCR tests and genetic probes for use in humans are expensive and often negative early in the disease. CSF may show rabies reverse transcriptase by PCR. MRI may reveal nonenhancing, ill-defined changes in the brain stem, hypothalamus, or subcortical matter.
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Varicella Zoster
VZV causes two different diseases, varicella and herpes zoster—with *transmission occurring via respiratory droplet or by direct contact*. VZV has an incubation period of 10-20 days, with contagion beginning 24 hours before the eruption appears and lasting until lesions have crusted.
134
Varicella Zoster
Chicken pox, shingles. *DNA virus herpes
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Varicella Zoster DX
Diagnosed by the clinical. Best initial test *Multinucleated giant cells* on Tzanck smear. Most accurate test is viral culture.
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Varicella Zoster Tx
A vaccine is available for infants,
| children, and adults and is routinely used for disease prevention. Adult: *acyclovir.*
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Varicella HX/PE
A prodrome consisting of *malaise, fever*, headache, and myalgia occurs 24 hours before the onset of the *rash*.
■ Pruritic lesions appear in crops over a period of 2-3 days, evolving from red macules to grouped central *vesicles* ("dewdrop on a rose petal") and then *crusting over*.
■ At any given time, patients have all stages of lesions over their entire body. The *trunk, face, scalp, and mucous membranes are involved, but the palms and soles are spared.*
■ In adults, chickenpox is often more severe, with systemic complications such as pneumonia and encephalitis.
138
Zoster HX/PE
Herpes zoster represents the recurrence of VZV in a specific nerve, with lesions *cropping up along the nerve's dermatomal distribution*.
Outbreaks are usually preceded by intense local pain and then arise as grouped blisters on an erythematous base (see picture).
■ Older patients with severe zoster may develop postherpetic
neuralgia.
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Lyme disease
Caused by Borrelia burgdorferi, which is *transmitted by the tick* Ixodes (also vector for Babesia)
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Lyme Disease PE
Hx/PE: Presents with the onset of rash with fever, malaise, fatigue, headache,
myalgias, and/or arthralgias. *Infection usually occurs after a tick* feeds for > 18 hours.
■ 1° (early localized disease): Erythema migrans begins as a small erythematous macule or papule that is found at the tick-feeding site and expands slowly over days to weeks. *The border may be macular or raised, often with central clearing Erythema Migrans ("bull's eye").*
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Lyme Disease PE Part 2
2° (early disseminated disease): Presents with migratory polyarthropathies, *neurologic phenomena (e.g., Bell's palsy)*, meningitis and/or myocarditis, and conduction abnormalities (third-degree heart block).
■ 3° (late disease): Arthritis and subacute encephalitis (memory loss and mood change).
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Lyme Disease Dx
Dx: Clinical diagnosis of erythema migrans is as follows:
■ ELISA and Western blot: Use the Western blot to confirm a or indeterminate ELISA. A ELISA denotes exposure but is not specific for active disease. Western blots sent without ELISA have high rates of false positives.
■ Tissue culture/PCR: Extremely difficult to obtain; not routinely done.
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Lyme Disease Tx
Tx: Treat early disease with doxycycline and more advanced disease (e.g., CNS or arthritic disease) with ceftriaxone.
