ID- Parasitic, Rickettsial and Spirochetal infections

Parasitic

___ infections are common in rural parts of Africa, Asia, and Latin America

Helminths and Arthropods (protozoa/bacteria)

What are two classes of parasites?

no

There is typically ___ immune reaction to living worms within a human host

3 multiple choice options

Hookworms

Ancylostoma duodenale and nectar Americanus are both examples of ___

Hookworm disease

Eggs present in soil hatch releasing infected larva that enter the skin via contact and migrate via the blood stream to the alveoli where they are coughed up and swallowed to end up in the GI tract (small intestine)

Hookworms

___ are a major cause of underdevelopment in children as they feed on blood

Duodenum and jejenum

Where do hookworms ultimately attach to the host?

pulmonary stage

Patients develop a dry cough, wheezing, blood tinged sputum and fever during the ___ of a hookworm infection

anorexia, diarrhea, abdominal pain, anemia, protein loss and hypoalbuminemia

Symptoms of severe hookworm infection in the GI stage?

Hookworms

___ consume host's RBCs so symptoms will mimic iron deficiency anemia

- stool = ova/parasites

- microcytic hypochromic anemia

- low serum iron

- hypoalbuminemia

- mild eosinophilia

Lab findings in hookworm infection?

- albendazole 400mg PO x 3 days or Mebendazole 500mg PO x 3 days

- effective BUT teratogenic

- ferrous sulfate if anemic

Tx for hookworm infection?

dog and cat hookworms

Cutaneous larva migrans is associated with ___

- albendazole 400mg x 3 days

Tx for cutaneous larva migrans?

pinworm infection

Enterobiasis is caused by ___

Enterobiasis vermicularis (pinworm)

M/C nematode infection worldwide

Person to person via ingestion of eggs through food, drink or contact

How is E. vermicularis transmitted?

hatch in duodenum, migrate to cecum where mating occurs, then to perianal skin to deposit eggs at night

Where do eggs hatch and migrate in enterobiasis?

nocturnal perianal pruritis

M/C clinical symptom of enterobiasis infection?

- scotch tape test

- visual identification of worms

- NO eosinophilia = no tissue invasion

Lab findings of enterobiasis infection?

- treat all members of household

- Mebendazole (single 500mg dose, retreat in 2wks) OR albendazole (single 400mg dose)

Tx for enterobiasis infection?

Protozoans

___ are single celled eukaryotic cells

cyst

Exposure to new environments causes a protozoa to shrink into a round armored form called a ___

Cyst

Is the trophozoite or cyst infective?

1 multiple choice option

Trophozoite form

When is a protozoa motile and replicating?

Amoebas, flagellates, ciliates and sporozoa

Four major groups of protozoa?

Amoeba

Naegleriasis is an example of a ___

flagellate

Trichomonas vaginalis is an example of a ___

sporozoas

Malaria and babesiosis are examples of ___

Histolytica

Which entamoeba species is pathogenic?

food or water

Transmission of amebiasis is through ingestion of cysts from fecally contaminated ___

overcrowding, poor sanitation and poor nutrition

Amebiasis is most common in tropical areas under conditions of ___

Intestinal or extraintestinal (portal circulation)

Amebiasis can be classified based on location as ___

Amebiasis

When spread through portal circulation ___ can form hepatic abscesses, lung abscesses and often cause death

intestinal

Mild to moderate colitis with abdominal cramping, flatulence and fatigue without hematochezia or melena can be seen in ___ amebiasis

intestinal amebiasis

In severe ___, symptoms include severe diarrhea, scant hematochezia, necrotic tissue in stools, fever, and tender abdomen w/ hepatomegaly

Amebiasis

When seeing someone from an endemic area always consider ___ for severe diarrhea and hematochezia before IBD

areas of greatest stasis (sigmoid and cecum)

Localized ulcerative colonic lesions of intestinal amebiasis are typically found in ___

Hepatomegaly (+/- abscess)

Most common extraintestinal feature of amebiasis?

Amebiasis

What caused this rash?

- stool specimen (ova/parasites)

- 3 fresh samples identify antigens/antibodies in severe cases

Lab findings for amebiasis?

- drink bottled water

- avoid ice

- avoid fresh fruits/veggies

- avoid street vendors/properly cook food

Prevention of intestinal amebiasis?

- hydration + pain control

- diagnostics (abdominal CT + colonoscopy)

- 2-4 weeks of metronidazole/tinidazole with paromomycin sulfate/diloxanide furoate

Tx of amebiasis?

Giardiasis

Which type of outbreak occurs when sewage contaminates drinking water?

Giardiasis

___ is harbored by rodents and beavers and can be acquired by 'drinking from a clear stream'

Small intestine wall

Where does a giardiasis trophozoite migrate and adhere?

Giardiasis

Which organism affects the intestinal wall by interfering with fat absorption?

Giardiasis

Greasy, frothy diarrhea with a bad odor is indicative of a ___ infection

- tinidazole 2g PO

- metronidazole 250mg PO TID x 5 days

- Nitazoxanide 500mg PO BID x 3 days

Tx for giardiasis

- Giardia lamblia

- Anaerobic cocci (Bacteroides fragilis, C. diff, Gardenerella vaginalis)

- Trichomonas vaginalis

- Entamoeba histolytica

Metronidazole is useful in treating which infections?

Trichomonas vaginalis

___ is a flagellated protozoan transmitted sexually that resides in the vagina or male urethra

Trichomonas vaginalis

Vaginal pruritis, dysuria, thin, watery, frothy and odorous discharge are signs of ___ infection

- wet mount of discharge

- Urinalysis

Workup for trichomoniasis?

- metronidazole 2g PO single dose

- tinidazole 2g PO single dose

Tx for trichomoniasis?

Toxoplasmosis

___ is found in humans, animals and birds but is most commonly found in cats

Toxoplasmosis

Humans transmit ___ by ingesting raw or undercooked pork, contaminated water, poor handling of cat litter (m/c), or through pregnancy

80

Over ___% of infections with toxoplasmosis are asymptomatic

3 multiple choice options

Toxoplasmosis

Retinochoroiditis is a sign of ___ infection along with fever, malaise, headache, lymphadenopathy, myalgia, arthralgia, neck stiffness, sore throat and hepatosplenomegaly

Toxoplasmosis

___ may resemble mononucleosis in clinical findings

Toxoplasmosis

In pregnancy, ___ is commonly asymptomatic for the mother but leads to neurological or ophthalmic conditions for the fetus

brain and eyes

in AIDS and fetuses, toxoplasmosis is toxic to the ___

- IgG and IgM titers (two samples 3-4 weeks apart)

- can isolate in tissue or fluid specimen

How is toxoplasmosis diagnosed?

- pyrimethamine, sulfadiazine, and leucovorin

Tx for toxoplasmosis?

Chagas

___ is caused by trypanosoma cruzi and is often acquired in childhood in South America/mexico

T. Cruzi

___ survives in rodents, opossums and armadillos

Chagas disease

Reduviid bug (kissing bug) is the vector of ___

Kissing

The feces of ___ bugs tunnel into humans and invade skin, macrophages, lymph nodes and the blood

asymptomatic

70% of people infected with chagas disease are ___

Heart, colon, and esophagus

Which organs are affected with chagas disease?

- chagoma (hardened red area - parasitic site of entry)

- romana sign (unilateral lid edema, conjunctivitis, and lymphadenopathy)

Initial signs of chagas disease?

Acute, latent and chronic phases

Three phases of chagas disease?

asymptomatic

During the latent phase of chagas disease, patients are usually ___ with low levels of parasites and (+) antibodies

Heart (Arrythmias, CHF, embolic disease + dilated cardiomyopathy)

GI (dysphagia, constipation, megacolon, megaesophagus and abdominal pain)

The chronic phase of chagas disease manifests as ___ problems

- acute: blood smear and direct examination

- chronic: serologic assay w/ evidence of T. Cruzi

Diagnostic testing for chagas?

- Nifurtimox and Benznidazole for acute

- no treatment for chronic disease

Tx of Chagas disease?

Malaria

M/C parasitic disease of humans?

equatorial

Malaria is most commonly found in ___ regions

Female mosquito

What is the vector of malaria?

Plasmodium falciparum

Which organism is responsible for most severe cases of malaria?

12-30 days

Incubation period of malaria?

3 multiple choice options

liver

Mosquitoes inject sporozoites which circulate to the ___ and rapidly infect hepatocytes

Merozoites

___ get released from the liver and infect erythrocytes in malaria

Fever

Hallmark symptom of malaria?

Malaria infection

Episodes of shaking chills, fever, diaphoresis over periods of 4-6 hours is indicative of

travelling

Consider malaria in all febrile patients with history of ___

malaria

Giemsa stained thick and thin blood smears are useful for diagnosis of ___

- chloroquine sensitive: chloroquine phosphate

- vivax and oval infections: chloroquine then primaquine /tafenoquine

- chloroquine resistant: coartem/malarone/quinine sulfate + doxy or clindamycin

- severe or complicated infections: artesunate IV or quinidine gluconate

Tx of malaria?

- Chloroquine: areas without resistant P. falciparum

- Malarone/Doxy: areas w/ multidrug resistant P. falciparum

- Mefloquine: areas w/ chloroquine resistant P. falciparum

- Primaquine: P. vivax and P. ovale coverage

- Tafenoquine: alt for P. falciparum

Prophylactic coverage against malaria for travelers?

Babesiosis

Malaria of the northeast?

deer tick (Ixodes scapulars) and blood transfusion

Babesia microti is spread primarily by ___

Babesiosis

Which tick borne illness begins with flu-like illness (headache, myalgias, fever, fatigue)

Babesiosis

___ is typically self limiting but can be severe in the elderly or those w/ prior splenectomy

Babesiosis

Lab findings of ___ include pancytopenia on CBC, intraerythrocytic parasites on Giemsa stain blood smear

- mostly self-limiting

- Atovaquone + azithromycin or Quinine + clindamycin

- consider RBC transfusion in severe cases

Tx of babeosis?

Rickettsial

Typhus, Rickettsiosis, Ehrlichiosis and Q fever are examples of ___ diseases

Rickettsial

___ organisms are small gram (-) rod/cocci bacteria that are obligate intracellular parasites

arthropods

Rickettsial diseases require ___ as a vector

endothelial

Rickettsial diseases have an affinity for ___ cells

Rickettsia prowazekii

Epidemic typhus is spread by ___

Epidemic typhus

___ is spread by lice/flying squirrels and proliferates in conditions of overcrowding and unsanitary conditions