Wk 4 Parasitic Skin and Tissue Infections

Question 1

Onchocerciasis (River Blindness)
symptoms: 
organism: 
lifecycle: 
Tx:
location:

Answer 1

symptoms: nodules under skin (adult worms in sub-Q tissue), severe itching, keratitis of cornea–>blindness
organism: Onchocerca volvulus (nemotode/roundworm)
lifecycle: black fly ingests microfilariae (embryonic larvae), adult nemotode found in humans
Tx: ivermectin (effective against microfilariae), doxycycline against symbiot W. pipientis
location: sub-Saharan Africa + Latin America

Question 2

Leishmaniasis
symptoms: 
organism: 
lifecycle: 
Tx:
location:

Answer 2

symptoms:
cutaneous-volcano-like skin sores, swollen glands near sores
mucocutaneous-can spread to mucous membranes (lips)
organism: Leishmania (protozoan)
lifecycle: sand fly, bundles up in macrophages of humans
Tx:sodium stibogluconate and meglumine antimoniate
miltefosine for resistant strains
liposomal amphotericin B (visceral form only)
location: East Africa, Asia, Latin America

Question 3

Chagas' Disease (American Trypanosomiasis)
symptoms: 
organism: 
lifecycle: 
Tx:
location:

Answer 3

symptoms:
acute-mild innate immune response, usually young
chronic indeterminate-80% of infected
chronic disease-40%, T. cruzi replicated intracellularly (evades immune response)–>MYOCARDITIS, megaesophagus, megacolon
organism: T. cruzi (trypanosome)
lifecycle: reproduces inside host cell, transmission through blood/organ donations
Tx: nifurtimox and benznidazole–oxidative stress via NADPH dependent dehydrogenases
location: ?

Question 4

African Sleeping Sickness (African Trypanosomiasis)
symptoms: 
organism: 
lifecycle: 
Tx:
location:

Answer 4

symptoms:
first stage–fever, headache, swollen lymph nodes, muscle and joint aches, possible rash
second stage–CNS involvement incl. somnolence (extreme sleepiness)
organism:T. brucei gamiense (less severe), T. brucei rhodesiense (acute)
lifecycle: Tsetse fly, waves of parasitemia
Tx: suramin (pentose phosphate pathway), pentamidine (mtDNA replication), eflornithine (ornithine decarboxylase), melarsoprol (unknown)
location:
T. brucei gambiense–West Africa
T. brucei rhodeniense–East Africa

Question 5

Lymphatic Filariasis Elephantitis
symptoms: 
organism: 
lifecycle: 
Tx:
location: 
Dx:

Answer 5

symptoms: lymphedema, elephantitis, hydrocele, foot lesions, epidermal nodules
organism: W. boncrofti
lifecycle: female mosquito (microfilarae), adult worms only in human lymphatic system
Tx: diethylcarbamazine–arachidonoic acid metabolic pathway (microfilaria)
location: Asia, Africa, West Pacific, Caribbean, South America
Dx: blood smear, samples @ night when microfilaria are present, IgG4 present in serum

Question 6

Toxoplasmosis
symptoms: 
organism: 
lifecycle: 
Tx:
location:

Answer 6

symptoms: usually asymptomatic, flu-like symptoms are possible. can cause miscarriage in newly infected pregnant women or birth defects–abnormal head size
organism: Toxoplasma gondii
lifecycle: cates, mice, birds, pigs, sheep are all hosts
Tx: only indicated in pregnant women and immunocompromised: atovaquone, sulfadiazine, pyrimethamine
location: worldwide