fungi, algae, protozoa & arthropod vectors
DESCRIPTION
Fungi, Algae, Protozoa & Arthropod Vectors. Fungi. Ubiquitous! Have a cell wall = chitin Are eukaryotes Have a true nucleus Reproduce sexually + asexually Most don’t cause disease Disease can be direct (infection) or indirect (ingestion of toxin produced by the fungus). - PowerPoint PPT PresentationTRANSCRIPT
Fungi, Algae, Protozoa & Arthropod Vectors
Fungi
• Ubiquitous!• Have a cell wall = chitin• Are eukaryotes• Have a true nucleus• Reproduce sexually + asexually• Most don’t cause disease• Disease can be direct (infection) or indirect
(ingestion of toxin produced by the fungus)
Coccidiodes immitisDomain: Eukarya
Kingdom: Fungi
Etiologic agent of coccidioidomycosis (“Valley fever”)
Narrow environmental range: semi-arid zones of SW US, Mexico, Central & South America
Dimorphic fungus:Saprophytic: environmental temp - filamentous fungus (mold) with branching septate hyphae + arthroconidiaParasitic: body temp: yeast form – large fungal spherules + division (endosporulation) to produce endospores
Arthroconidia → spores → inhalation by mammals → spherules → endospores
“Imperfect fungus” – no known sexual stage
Algae
• Aquatic or semi-aquatic environments• Have a cell wall (cellulose)• Are eukaryotes• Have a true nucleus• Photosynthetic (chloroplasts)• Reproduce sexually + asexually• Disease most often = indirect (toxic algae)
Algae: Cyanobacteria
Most common causes of toxic blooms:Anabaena, Aphanizomenon, and Microcystis species
Hepatotoxic: cause acute submassive to massive hepatocellular necrosis → liver failure
Prototheca wickerhamii
Chlorella species
Algae: rarely cause infectious disease
Slime molds and water molds
• Slime molds: ameboid cells – Phagocytic– Cellular slime molds: single cells, can aggregate to
form a “slug” → fruiting body + spores → dissemination
– Plasmodial slime molds = multinucleated; diploid cells; also spread by fruiting body/spores
• Water molds = oomycetes– Cell wall = cellulose– Flagellated
Pythium insidiosumDomain: Eukarya
Kingdom: Protista
Oomycete (Water mold)
Etiologic agent of pythiosis (“Kunkers”)
Warm, wet environments
Pythium insidiosum
Protozoa
• Eukaryotes that don’t fit into any of our other categories
• True nucleus• No cell wall, no chloroplasts• Reproduce sexually + asexually• Most don’t cause disease• Disease causing protozoa can be free
living/opportunists or obligate intracellular parasites with a complex life cycle
Toxoplasma gondiiDomain: Eukarya
Kingdom: Protista
Apicomplexan
Etiologic agent of toxoplasmosis
Life cycle of Toxoplasma gondii
Definitive host
Int. hosts
Vector transmitted diseases
• vec·tor (vktr)n.1. Mathematicsa. A quantity, such as velocity, completely specified by a magnitude and a direction.
• b. A one-dimensional array.• c. An element of a vector space.• 2. Pathology An organism, such as a mosquito or tick, that
carries disease-causing microorganisms from one host to another.
• 3. Genetics A bacteriophage, plasmid, or other agent that transfers genetic material from one cell to another.
• 4. A force or influence.• 5. A course or direction, as of an airplane.
Vector transmitted diseases
• Mechanical vectors• Biological vectors• Arboviruses
Plasmodium species Domain: Eukarya
Kingdom: Protista
Etiologic agent of malaria – 5 species involved = P. vivax, P. falciparum, P. malariae, P ovale and P. knowlesi
Vector = Anopheles species mosquitos
Life cycle of Plasmodium sp.
Rickettsia rickettsiiDomain: Prokarya
Kingdom: Bacteria
Vector: ticks – Dermacentor andersoni, Dermacentor virabilis and Rhipocephalus sanguineous)
Disease: Rocky mountain spotted fever
3 host tick life cycle