Parasitology 5 Flashcards
Describe the location of Leishmaniasis infection
blood and tissues
Which forms of Leishmaniasis cause only cutaneous infection?
L tropica
L major
Which forms of Leishmaniasis cause cutaneous and mucocutaneous infection?
L mexicana
L brazillensis
Which forms of Leishmaniasis cause visceral infection?
L chagasi
L donovani
L infantum
What is the vector of Leishmaniasis?
sand fly
Describe the lifecycle of Leishmaniasis
Vector borne- sand fly is infected when it takes a blood meal from infected host. Parasites develop in the sand fly, transmitted to a new host when fly bites again
Within humans, the leishmania is adapted to live in WBC and avoid being degraded
_____ and ______ are important reservoirs of Leishmaniasis
dogs and rodents
_______ transmission of Leishmaniasis has been documented in dogs
vertical
The great majority of ______ cases of Leishmaniasis occur in India, Bangladesh, Nepal, Sudan, and Brazil
visceral
Describe the epidemiology of Leishmaniasis
- 350 million at risk
~12 million infected
~2 million new cases/year
~60,000 deaths/year
tropical and subtropical regions
Describe the presentation of cutaneous Leishmaniasis
- Starts as a bump then an ulcerative sore at primary site; satellite lesions
- abundant amastigotes in lesions
- spontaneous healing with scarring
______ may reduce the duration of cutaneous Leishmaniasis lesions and help them heal faster
Fluconazole
Describe the presentation of mucocutaneous Leishmaniasis
- metastasis months to years after primary lesion heals
- ulceration nasopharynx tissues, amastogotes in lesions
For both mucocutaneous and visceral Leishmaniasis, ________ leads to immunity
chemotherapeutic cure
Describe the presentation of visceral Leishmaniasis
Onset at 2-12 months, fever and wasting with hepatosplenomegaly
How is Leishmaniasis diagnosed
biopsy or aspirate the lesion, stain with Giemsa, look for amastigotes.
In US, CDC does DNA tests
Describe treatment for cutaneous Leishmaniasis
typically self-resolves with scarring
L. major treated with fluconazole
Describe treatment for mucocutaneous Leishmaniasis
Antimonials- not always effective and side effects
Amphotericin B is an alternate but expensive & iv daily
Describe treatment for visceral Leishmaniasis
miltefosine- drug of choice, given for 4 weeks, cures 94% Amphotericin B is an alternate
In eastern and southern Africa, African Trypanosomiasis is caused by Trypanosoma _________
rhodesiense
In western and central Africa, African Trypanosomiasis is caused by Trypanosoma ________
gambiense
What is the vector for Human African Trypanosomiasis?
tsetse fly
Contrast the progression of Western vs Eastern Human African Trypanosomiasis
Western: reservoir is human, chronic (years to progresion)
Eastern: reservoir is antelope, cattle; rapid progression in 1-4 weeks
both 100% mortality without treatment
The African Trypanosomiasis parasite is free floating in the blood stream and undergoes __________ to avoid host immunity
antigenic variation
Describe the epidemiology of HAT
Exclusively sub-Saharan Africa
Re-emerging
60 million people at risk
How is HAT diagnosed?
direct examination of blood, lymph, and CSF (rhodesiense)
What is Winterbottom’s sign?
Enlargement of posterior cervical lymph nodes seen in African Trypanosomiasis
What drugs are used to treat early stage trypanosomiasis?
Pentamidine: useful for gambiense, well tolterated
Suramin: useful for rhodesiense
What drugs are used to treat late stage trypanosomiasis?
Melarsoprol: discovered in 1949, used against both forms. Arsenic derivative with many side effects including fatal encephalopathy (3% to 10%).
Eflornithine: Only effective against T.b. gambiense. Less toxic but infusion every 6 hr for 14 days.
What organism causes Chagas disease?
Trypanosoma cruzi
What is the reservoir for Trypanosoma cruzi?
rats, cats, dogs, wild animals
What is the location of Trypanosoma cruzi?
blood, lymphatics & tissues (intracellular)
What is the vector of Trypanosoma cruzi?
reduviid bug
How is Trypanosoma cruzi transmitted?
Bite of infected reduviid bug, transfusion, transplantation, IVDU, possibly vertical
Contrast the epidemiology of Chagas in rural vs urban settings
rural: vector/reservoir in proximity to human dwellings
urban: contaminated blood supplies; IV drug use
How is spread of Chagas prevented?
Screen blood supply
good housing
vector control
Describe the progression of Chagas disease
Acute: 2-4 months fever, chagoma, hematogenous spread
Chronic: 10-20 years, damage to nerve, muscle, heart, esophagus, colon. Death from sudden heart attack is common
How is Chagas diagnosed?
acute: trypomastigotes in blood
chronic: xenodiagnosis
Recently approved strip assay
How is acute chagas treated?
Benznidazole or Nifurtimox
Neither FDA approved, get from CDC
What is the location of Trichomoniasis?
Urogenital- luminal
There are no ________ or ______ stages in the life cycle of Trichomoniasis
free living or encysted
How is Trichomonas vaginalis transmitted?
direct sexual contact, rarely non-sexual contact
70% of females infected with Trichomonas vaginalis are ______
asymptomatic
Describe signs of Trichomoniasis in women
vaginitis, burning and itching
inflammation of squamous epithelia
“frothy” vaginal discharge with unusual odor
Describe signs of Trichomoniasis in men
itching, irritation inside penis
burning after urination or ejaculation
mild discharge
List complications of Trichomoniasis
preterm delivery, LBW
increased risk of acquiring HIV
People who have been successfully treated for Trichomoniasis can be _______
re-infected
How is Trichomoniasis diagnosed?
microscopic observation of motile parasites
DNA test is available now at major centers
What is the treatment for Trichomoniasis?
metronidazole or tinidazole
