Download thrush

Eukaryote agents of disease
Protists, Fungi and Helminthes
Apicomplexa
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Plasmodium falciparum
Babesia microti
Cryptosporidium
Toxoplasma gondii
Malaria
• Several species within the genus, Plasmodium
– P. falciparum
– P. ovale
– P. vivax
• Severity and treatability varies by species
• Anopheles spp. mosquitoes are vectors and definitive
hosts, where sexual reproduction occurs, transmit
through injection of saliva
• Asexual stage occurs in humans when
merozoites/trophozoites reproduce in RBC
Cryptosporidium spp.
• Cause cryptosporidiosis
• Many mammalian reservoirs
• Cysts are highly resistant to environmental stress and
water treatment (i.e. chlorination)
• Cysts passed in feces of host, survive long periods in
water where they may be ingested by next host
• May also be transmitted by direct fecal-oral route
• Causes diarrhea, which may be severe in
immunocompromised patients
• Massive outbreaks (Milwaukee) can occur when water
treatment malfunctions
Babesia microti
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Causes babesiosis
Often asymptomatic
flu-like symptoms usually not fatal
Difficult to treat
Parasite resemble P. falciparum in RBCs
rodents are main reservoir
Transmitted by black-legged ticks (Ixodes scapularis) to
humans
Toxoplasma gondii
• Causes toxoplasmosis
• May be asymptomatic, or resemble low-grade infection
resembling mononucleosis
• May lead to still births in congenital infections
• Contracted through contact with cat feces, or
undercooked beef
• Many mammals and birds may be infected but cats are
definitive hosts
Mastigophora
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Giardia intestinalis (lamblia)
Trypanosoma cruzi
Trypanosoma brucei gambiense, T.b. rodesiense.
Trichomonas vaginalis
Leishmania spp.
Trypanosomes
• Chaga’s disease- Trypanosoma cruzi
• African Sleeping Sickness
– Trypanosoma brucei gambiense
– T.b. rodesiense.
Leishmania spp.
• Visceral leishmaniasis (kala-azar)
• Cutaneous leishmaniasis (Baghdad boil, oriental sore
other names)
• Muco-cutaneous leishmaniasis (espundia)
• Transmitted by sand fly
Trichomonas vaginalis
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Causes trichomoniasis, vaginitis
Symptoms include profuse vaginal discharge
Limited by normal vaginal acidity
Male prostate, seminal vesicles, urethra may be infefcted
Giardia intestinalis
• One of the most common protozoan parasites in U.S.
• Adheres to intestinal epithelium and disrupts absorption
of water and nutrients
• Fecal-oral route of transmission, especially through
water contaminated with feces of humans or reservoirs
• Many mammals can be reservoirs
Sarcodina
• Entamoeba histolytica
• Naegleria fowleri
• Acanthamoeba castellani
Entamoeba histolytica
• Amebic dysentery
• Severity varies by strain and host
• Invade intestinal mucosa and may result in long-term
infection and tumor-like masses (amebomas)
• Extra intestinal infection may result in liver abcess
• Severe cases may result in malnutrition
• Many animals may harbor these parasites in their
intestines
Free-living amebas
• Naegleria fowleri may enter through the nose of host
from fresh water
– Enters NS through olfactory epithelium and into brain
where they cause severe tissue damage and
hemorrhage
– Often fatal after only a few days
– Treatment with Amphotericin B is possible if diagnosis
is made quickly
• Acanthamoeba castellani is Similar to N. fowleri,
however, entry may be through ulcers or damaged
tissues, such as corneal abrasions associated with
contact lenses
Fungi
• Medical mycology is the study of disease-causing fungi
• Can cause infection (Candida etc..) or intoxications (see
below)
• Many fungi are saprophytes and live primarily off of dead
organic matter
Intoxicating fungi
• Aflatoxins on moldy foods- Aspergillus flavus
• Ergotism- Claviceps purpurea
• Poor indoor air quality-black mold, Stachybotriys sp.
Candida albicans
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candidiasis (oral, intestinal, vaginal, cutaneous)
Often called thrush
Vaginitis (yeast infection)
Diaper rash in babies
Can invade many internal tissues and cause
toxic reactions (including sepsis)
Dermatophytes
• Superficial cutaneous mycoses caused by three genera:
Trichophyton spp. Microsporum, and Epidermophyton spp.
– Tinea pedis- atheletes foot (feet and hands)
– Tinea cruris-jock itch
– Tinea corporis (ringworm that actually forms the characteristic ring)non-hairy surfaces of body
– Tinea capitus (ringworm of scalp)
– Tinea barbi (ringworm of facial hair)
Not scientific names of organisms
but names of diseases
Other fungal skin diseases
• Sporotrichosis- Sporothrix shenckii
• Blastomycosis- Blastomyces dermatitidis
Fungal respiratory diseases
• Coccidiomycosis- Coccidioides immitis
• Histoplasmosis- Histoplasma capsulatum
• Cryptococcosis- Filobasidiella (Cryptococcus)
neoformans
• Pneumocystis pneumonia- Pneumocystis carinii
• Aspergillosis- Aspergillus spp.
Helminthes
• Platyhelminthes-flatworms
– Cestodes: tapeworms
– Trematodes: flukes
• Nematoda-roundworms
– Filarial worms
– Others
Tapeworms (cestodes)
• Beef tapeworm- Taenia saginata- undercooked beef
• Pork tapeworm- Taenia solium- undercooked pork
– Cysticercosis results from the ingestion of human
feces. Cysticerci form in tissues all around the body
including the brain can result in epilepsy and death
Other Tapeworms
• Broad fish tapeworm- Dibothrocephelus latus
(Dyphyllobothrium latum) eating undercooked freshwater
fish
• Hydatidosis or hydatid disease- Echinoccocus
granulosus, dog feces cysts form in tissues including the
brain
• Vampirolepis (Hymenolepis) nana- most common
cestode infection of humans, animal feces
• Dipylidium caninum- children accidental hosts by
ingesting fleas
Blood Flukes
Schistosomiasis (bilharzia)
• Schistosoma mansoni, S. japonicum, S. haemotobium
and others
• Distributed throughout Africa, South Asia and equatorial
South America (S. mansoni)
• Female lives within body groove of male, female body
adapted for laying eggs in blood vessel.
• Eggs pass in human feces and into natural water
• Miracidium invades snail (intermediate host)
• Cercaria invades human in water
• Cercarial dermatitis (swimmers itch)-various genera of
schistosomes- an allergic reaction to a parasite that
doesn’t normally infect humans
Other Flukes
• Sheep fluke- Fasciola hepatica
– Snail intermediate host
– Infective stage on aquatic vegitation
• Chinese liver fluke- Chlonorchis sinensis
– Snail intermediate host
– Second intermediate host commonly Grass Carp
– Survive meat preparation other than cooking
• Lung fluke- Paragonemus westermani
– Acquired through eating raw crabs
– Metacercariae bore through GI tract and penetrate
the diaphragm and into the bronchioles, eggs
transported out of lungs by cilia, swallowed and
expelled with feces
Nematodes: Hookworm
• Main species :Ancelystoma caninum and Necator
americanus
• Larvae penetrate skin and migrate to circulatory system,
then travel to lungs, coughed up and swallowed, adults
reside in intestines as blood feeders
• Cutaneous larva migrans (creeping eruption) caused by
hookworms that can’t get into the blood stream
Nematodes: Filarial worms
• Onchocerciasis, River blindness
– caused by Onchocerca vovulus a filarial worm that
migrates to various tissues including the eyes
– Transmitted by black flies (Simuliidae: Simulium
damnosum)
• Loaiasis
– Caused by Loa loa, filarial worm, that can end up in
the eye but does not result in blindness
– Transmitted by deer flies (Tabanidae: some African
spp. of Chrysops)
Lymphatic Filariasis
• Main species that cause LF are Wuchereria bancrofti
and Brugia malayi
• Several species of mosquitos are vectors including
Culex spp. Aedes spp.
• Periodic and subperiodic forms of transmission cycle,
may also be diurnal or nocturnal
• Filarial worms cause inflammation and block the flow of
lymph- this can result in elephantiasis
Common Nematode infections
Disease
Nematode species
Transmission
Ascariasis
Ascaris lubricoides
ingestion of
contaminated soil
Whipworm
Trichuris trichiura
ingestion of
contaminated soil
Pinworm
Enterobius
vermicularis
ingestion or inhalation
of eggs
Other Nematode infections
Disease
Nematode species
Transmission
Trichinosis
Trichinella spiralis
Undercooked pork
Stongyloidiasis
Strongyloides
stercoralis
Penetration of skin
Can complete cycle in
one host, easy
transmission
Anasikiasis
Anisakis spp.
Undercooked fish
Raccoon roundworm
infection
Baylissascaris
procyonis
Ingestion of
contaminated soil
Guinea worm
Dracunculus
medinensis
Ingestion of
crustacean in water