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 immitis Domain: 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 + arthroconidia Parasitic: 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 insidiosum Domain: 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 gondii Domain: 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 rickettsii Domain: Prokarya Kingdom: Bacteria Vector: ticks – Dermacentor andersoni, Dermacentor virabilis and Rhipocephalus sanguineous) Disease: Rocky mountain spotted fever

3 host tick life cycle