Parasitic & Fungal Infections Flashcards
Toxoplasmosis gondii
what animal is the defifinitive host?
cats but also found in birds and many other mammals
toxoplasmosis gondii
Where do you get it from?
contaminated soil from cat feces, contaminated undercooked meat.
toxoplasmosis gondii
What are dangers for pregnant mothers?
It passes through placenta, moms shouldnt clean cat litter
toxoplasmosis gondii
symptoms
Can be asymptomatic
Fever, malaise, headache, sore throat.
Cervical lymphadenopathy
toxoplasmosis gondii
Dx
Positive IgG and IgM serologic tests
toxoplasmosis gondii
congenital infection
After acute infection of seronegative mothers, CNS abnormalities and retinochoroiditis seen in offspring.
eye issues for baby
Earlier infections more likely to have serious outcomes: SAb, stillbirth, neurologic problems,
toxoplasmosis
infection in immunocompromised
Reactivation leads to encephalitis, retinochoroiditis, pneumonitis, myocarditis.
Positive IgG but negative IgM serologic tests.
Encephalitis with necrotizing brain lesions
Chorioretinitis
Pneumonitis
toxoplasmosis
Dx through CT or MRI
*Multiple ring-enhancing lesions
toxoplasmosis
Triad of Sx for congenital infection
Retinochoroiditis/chorioretinitis
Hydrocephalus
Intracranial calcifications
toxoplasmosis gondii
Tx
for normal, compromised, pregnant
usually not needed for immunocompetent.
For AIDS full therapy for 4–6 weeks followed by maintenance therapy with lower doses of drugs.
Treat primary infection during pregnancy to reduce risk of fetal transmission.
Retinochoroiditis: treatment advocated if decrease in visual acuity, multiple or large lesions, macular lesions, significant inflammation, or persistence for over a month.
toxoplasmosis gondii
Medications
Pyrimethamine orally once daily plus sulfadiazine(sulfonamide) orally four times daily, with folinic acid/leucovorin once daily.
toxoplasmosis gondii
AIDS treatment/meds
HIV+ patents with low CD4+ counts may require prophylaxis with trimethoprim/sulfamethoxazole to prevent symptomatic disease
toxoplasmosis gondii
Tx for pregnant
is spiramycin(macrolide) orally three times daily until delivery.
reduces frequency of transmission to fetus by 60%
does not cross placenta,
Toxoplasmosis gondii
prevention
Cook meat until no longer pink inside
Cats
Change cat litter box daily (not if pt is pregnant or HIV+)
Hand hygiene
Feed cat well-cooked food
Garden soil: wash hands, wash produce
Amebiasis
What are the infectious agents
Entamoeba dispar, Entamoeba moshkovskii, Entamoeba histolytica
Amebiasis
how do you get infected?
Ingestion from fecally contaminated food or water by person to person spread
Present worldwide but most prevalent in tropical areas with crowding, poor sanitation and nutrition
Disease follows penetration of the intestinal wall
Amebiasis
Dx
Diagnosis is most commonly made by finding organisms in stool
Serologic tests may also be utilized
Liver abscesses can by seen via U/S, CT, or MRI
Amebiasis
Tx
metronidazole or tinidazole
amebiasis
prevention
Safe water and fruit/vegetable supplies
Sanitary disposal of human feces
Adequate preparing of food
Avoidance of fly contamination
Handwashing
malaria
Transmission and endemic areas
Exposure to (female) anopheline mosquitoes in a malaria-endemic area
South and Central America, Africa, the Middle East, Southeast Asia
Caused by Plasmodium parasites
Plasmodium falciparum responsible for nearly all severe disease
plasmodium falciparum
Severe Sx
SEVERE
Cerebral malaria, severe anemia, hypotension, pulmonary edema, acute kidney injury, hypoglycemia, acidosis, and hemolysis.
plasmodium
Dx
identified through blood smears or rapid test
plasmodium
patho
goes to liver then blood infecting erythrocytes
plasmodium
classical presentation
(3 stages)
Cold stage (sensation of cold, shivering)
Hot stage (fever, headaches, vomiting; seizures in young children); and
Finally sweating stage (sweats, return to normal temperature, tiredness).
plasmodium
more common presentation
Fever
Chills
Sweats
Headaches
Nausea and vomiting
Body aches
General malaise
Plasmosium
clinical manifestations
mainlyP falciparum, can include severe anemia; hypotension and shock.(RBCs being blown apart)
Hypoglycemia – diminished gluconeogenesis
Acidosis – microcirculatory flow affected, anaerobic glycolysis
Renal impairment - infarcts, capillary leakage
Pulmonary edema - sequestration of parasitized RBCs in lungs and/or cytokine-induced leakage from pulmonary vasculature
plasmodium
Tx
Chloroquine is first line
P. falciparum is somewhat resistant, use Artemisinin (artesunate, artemether) generates free radicals that damage parasite proteins
plasmodium
Tx for severe malaria
Medical emergency – IV Artesunate
Maintenance of fluids and electrolytes
Respiratory and hemodynamic support
Potential blood transfusions/anticonvulsants/antibiotics/hemodialysis
Plasmodium
prevention
Bed nets, insecticides
Travelers to endemic areas:
Chloroquine
Malarone
Mefloquine
Doxycycline
Primaquine
Tafenoquine
Pinworms
Most common helminth infection in US
Enterobius vermicularis
Usually children under 18 (typically 5-14), or those who are institutionalized
Enterobius vermicularis (pinworm)
Main route of infection
oral after scratching
or exposure to eggs from contaminated food/fomites
Enterobius vermicularis
pathophys
Eggs hatch in duodenum and larvae migrate to cecum. Females mature in a month, and remain viable for about another month; migrate through anus nocturnally to deposit large numbers of eggs on perianal skin
Enterobius vermicularis
Most telling Sx
Perianal pruritus, particularly at night
INTENSE ITCHING AT NIGHT, possible bacterial infection from scratching
Enterobius vermicularis
Dx
listen to hx and Characteristic eggs on perianal skin detected using clear sticky tape (Scotch tape test)
Sometimes worms seen in feces
Enterobius vermicularis
Tx
Oral single dose: albendazole, mebendazole
Redose in 2 weeks because of frequent reinfection
Treat family members and Washing clothes and bedding in hot water to kill eggs
what are helminths
worm parasites
hookworm agent
Ancylostoma duodenale and Necator americanus
Found in feces of infected animals
Look for patients who were walking barefoot
common in tropic/subtropic regions
hookworm life cycle
Eggs deposited on warm moist soil and hatch, releasing larvae that are infective for a week
*Patient will sometimes report walking barefoot
hookworm
life cycle
larvae penetrate skin and migrate in bloodstream to pulmonary capillaries.
In lungs, larvae penetrate into alveoli and are carried by ciliary action upward to bronchi, trachea, mouth.
After being swallowed, they reach & attach to small bowel mucosa and mature to adult worms.
Attach to intestinal mucosa and suck blood. Blood loss is proportionate to worm burden.
hookworm
Signs and Dx
Transient pruritic skin rash and lung symptoms
Anorexia, diarrhea, abdominal discomfort
Iron deficiency anemia
Characteristic eggs and occult blood in the stool
hookworm
clinical manifestation
Often asymptomatic
Anemia due to blood loss in gut
Blood loss in stools not visibly apparent
New infection: epigastric pain, anorexia, diarrhea
Chronic infection: abd pain, anorexia, diarrhea, iron-deficiency anemia, protein malnutrition
hookworm
Dx
characteristic eggs in stool
possible blood in stool
hookworm
Tx
ivermectin single dose or albendazole once daily for 3 days
tapeworms
main beef and pork agent
*Beef: Taenia saginata (eating raw or undercooked beef)
*Pork: Taenia solium (eating undercooked pork)
tapeworms
Sx
Patient complains of GI symptoms, potentially including anorexia and weight loss
tapeworms
Dx
egg in stool
tapeworms
Tx
usually a single dose of praziquantel
Ascariasis
Ascaris lumbricoides
most common intestinal helminth, LARGE white worms, common in children
contaminated soil is ingested
Ascaris lumbricoides
Sx and Dx
Most are asymptomatic
Heavy infection may cause intestinal discomfort
Malnutrition and/or even *obstruction
Diagnosis made by ID of eggs in stool or after adult worm emerges from mouth, nose, or anus
Fluke spp and transmission
Clonorchis sinensis
Opisthorchis viverrine
Fascilla hippatica
Undercooked fish, crabs, water plants in endemic areas
Roundworm agent and transmission
Trichinella spiralis
Trichinosis
Muscle tissue damage
Spread by ingestion of raw, most commonly pork
trichinosis
Sx
are asymptomatic; however, GI complains may be present
Can progress to fever, *myalgias, periorbital edema, headaches, cough, rash
Trichinosis
Dx
elevated muscle enzymes, serological tests, proceeding to muscle biopsy only if necessary
trichinosis
Tx with early detection
mebendazole, albendazole
Filariasis
Wuchereria bancrofti
Wuchereria bancrofti
Sx
Chronic progressive swelling of extremities and genitals
(elephantitis)
Loiasis (Loa loa)
transmission and Sx
Transmitted by chrysops flies
Larvae develop into adult worms and *migrates to eye
Rocky Mountain Spotted Fever
Agent, transmission, endemic area, time of year
Rickettsia rickettsii
Exposure to infected tick bite in an endemic area
Half of cases are from 5 states: North Carolina, Tennessee, Oklahoma, Missouri, and Arkansas
Usually seen in May-August when ticks are most active
Rickettsia rickettsii
Patho
R. rickettsii likes to damage vascular endothelial cells.
Direct vascular injury; endothelial cells produce prostaglandins that cause increased vascular permeability
Hyponatremia from release of antidiuretic hormone as an appropriate response to hypovolemia/reduced tissue perfusion (leaky vasculature}
RMSF
Sx
fever/headache/rash; fever/rash/history of tick bite
rash is delayed
non blanching rash
Early phase, nonspecific signs/symptoms: fever, headache, malaise, myalgias, arthralgias
Nausea is common. Children may have severe abdominal pain
may be fatal
RMSF
Rash
90% of patients, not usually at initial contact with clinician
*Rash on palms and soles is highly characteristic
RMSF
Rash first presentation
First peripherally on wrists/ankles; spreads
centripetally. Involvement of palms/soles is important Dx feature.
RMSF
CBC with diff
Usually normal WBC at presentation, left shift. May be anemia, thrombocytopenia, hyponatremia
As illness progresses, thrombocytopenia becomes more severe
RMSF
Tx
doxycycline 100mg twice daily for 5-7 days (10-14 days for severe cases); treat until afebrile for 2-3 days
Lyme disease agent, transmission, region, time
most common
Caused by Borrelia burgdorferi
Infection transmitted to humans by blood-feeding anthropods: mosquitoes, ticks, fleas
Most cases are reported from the northeastern and north central regions of the US
Occurrence more common late spring and summer (May to July)
Lyme disease
Early localized
ncludes erythema migrans “bulls-eye” rash with central clearing(EM – next slide) and nonspecific flu-like findings that can include myalgias, arthralgias, headaches, and fatigue.
lyme disease
Early disseminated
(weeks to several months after tick bite): can include acute neurologic (aseptic meningitis with headache and stiff neck or facial palsy) or cardiac involvement (with arrhythmias); may be first manifestation of Lyme disease.
Lyme Disease
Late stage
(months to few years after the onset of infection; may not be preceded by early localized or disseminated disease): arthritis in one/few joints is most common, neurologic manifestations (encephalopathy or polyneuropathy) can occur.
lyme disease
Dx
Exposure to tick habitat + erythema migrans or at least 1 late manifestation of the disease + lab confirmation
Dx confirmed by antibody testing using enzyme immunoassay or immunofluorescence assay; confirmation of positive result with Western blot
Lyme diseae
Tx
Prophylactic antibiotics following tick bites in recommended in certain high-risk situations: doxycycline 200mg orally
Doxycycline 100mg orally twice daily for 10 days
Histoplasma capsulatum
Histoplasmosis transmission and region
Exposure to bird and bat droppings; common along river valleys (esp. *Ohio River and Mississippi River valleys).
Fungus isolated from soil contaminated
Infection presumably takes place by inhalation
Histoplasma capsulatum
Sx
More respiratory symptoms seen
Pts most at risk for parasitic or fungal infections
Cancer, children, AIDS, immunocompromised
Histoplasma capsulatum
Clinical presentation
More respiratory symptoms seen
Mostly asymptomatic, variable symptoms from mild to severe
Usually have respiratory symptoms if present
Past infection - pulmonary and splenic calcification noted incidentally
More severe infections typically have symptoms as atypical pneumonia
Can have a macular/papular rash
Chronic Pulmonary Histoplasmosis
Xrays:
apical cavities, nodules, infiltrates
Histoplasmosis
who is affected?
normally immunocompromised pts
Histoplasmosis
Dx
Sputum culture rarely positive, maybe in chronic disease
Antigen testing in acute disease.
Chest x-ray
Combination of urine and serum antigen assays: 83% sensitivity for Dx acute pulmonary.
Blood or bone marrow cultures (immunocompromised patients with acute disseminated disease) positive >80% of the time, take several weeks for growth.
Histoplasmosis
Tx
Most cases resolve within 4 weeks
Progressive localized disease and mild/moderately severe nonmeningeal disseminated disease, treatment of choice is itraconazole (disrupts cell membrane integrity)
Orally for up to 12 weeks depending on severity of illness
Severe disease:
IV amphotericin B for 1-2 weeks followed by itraconazole for total of 12 weeks
Patients with AIDS-related histoplasmosis require lifelong suppressive therapy withitraconazole orally
Cryptococcosis
Cryptococcosis
Cryptococcus neoformans
*Pacific northwestern region
*Look at occupation (Farmer?)
*Most common cause of fungal meningitis.
Cryptococcosis
where is it found?
Found worldwide in soil and on dried pigeon dung
Cryptococcosis
Clinical presentation
Pulmonary
Varies from mild/moderate cough to ARDS
CNS
Meningitis and encephalitis
Altered mental status, ataxia, headache, coma
Visual disturbance common
Pustular skin rash
Cryptococcosis
Dx
***Sputum culture (if having more pulm symptoms)
*Lumbar puncture: **
increased opening pressure, variable ↑WBCs, increased protein, decreased glucose
India ink stain of CSF reveals budding, encapsulated fungi.
Pneumocystitis
PJP
Pneumocystis jirovecii pneumonia (PJP)
Overt infection is a subacute interstitial pneumonia that occurs among older children and adults with altered immunity
Cancer, transplants, AIDS, receiving corticosteroids
*Occurs in up to 80% of AIDS patients who are not receiving prophylaxis
PJP
Clinical presentation
Usually limited to pulmonary
Onset may be subacute with only dry cough or shortness of breath
Hard to cough anything up due to thick secretions
May present with spontaneous pneumothorax and/or additional symptoms of fever, fatigue, weight loss
Note decreased oxygen saturation on exam
PJP
Dx
Sputum cultures
Positive beta-D-glucan** (detects fungal cell wall)
**Chest x-ray & CT scan** (next slides)
**Ground glass opacification
Can start empiric therapy for PJP if disease is suspected clinically
PJP
Tx
Oral trimethoprim-sulfamethoxazole is the preferred treatment
Coccidioidomycosis
Valley fever
Coccidioides immitis or C. posadasii
*Found in soil and causes infections when inhaled
*Southwestern US and parts of Mexico and Central South America
Valley fever
Acute infection
: influenza-like illness, fever, backache, headache, fatigue, and cough. Erythema nodosum common
valley fever
dissemination
Dissemination may result in meningitis, bony lesions, or skin and soft tissue abscesses
Common infection in patient with AIDS
Aspergillosis
Agent
Aspergillus fumigatus
Inhalation of spores of fungus
Aspergillosis
Predisposing factors
** leukemia, bone marrow or organ transplantation, corticosteroid use, advanced AIDS**
Aspergillosis
Most common cause of non-candida invasive fungal infection
Most common cause of non-candida invasive fungal infection in *transplant recipients and in patients with hematologic malignancies
Aspergillosis
what are the most common disease sites
Pulmonary, sinus and CNS are most common disease sites
Aspergillosis
Tx
antifungal drugs
Fluke Sx
Most aSx or mild GI
If untreated progress to serious disease, advanced GI
Fluke Dx and Tx
Clinical findings or eggs in stool
Praziquantel
