CHAPTER 14- PARASITIC & FUNGAL INFECTIONS

WHY IS THIS IMPORTANT? Parasitic infections affect billions of people in the world. Fungal infections are usually opportunistic infections and have increased with the number of immunocompromised individuals. Parasites can be divided into two groups: Protozoans – microscopic, single-celled eukaryotes. Helminths – macroscopic, multicellular worms.

SIGNIFICANCE OF PARASITIC INFECTIONS Parasitic infections are a major problem worldwide. More than 500 million people are infected with malaria. More than 2 million (mostly children) die each year from malaria. Entamoeba are intestinal parasites that infect 10% of the world population. Trypanosoma parasites infect 16 million people in Latin America each year.

SIGNIFICANCE OF PARASITIC INFECTION

FUNGAL INFECTIONS The study of fungi is known as mycology and scientist who study fungi is known is a mycologist A fungus is a member of a large group of eukaryotic organisms Microorganisms such as yeasts and molds, as well as the more familiar mushrooms Over 60,000 species of fungi are known Fungi are important for the environment. They are normally harmless to humans Fungi can be opportunistic pathogens.

Structure The main body of most fungi is made up of fine, branching, usually colourless threads called hyphae ( PG 310) Several of these these hyphae, all intertwining to make up a tangled web called the mycelium Most fungi are multinucleate and multicellular organisms with cross wall called septa or aseptate (coenocytic) Yeasts are unicellular One major difference is that most fungi have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose

Single Hyphae

Reproduction Life cycle involves the fusion of hyphae from two individuals (Male & Feamle Each parent hyphae has haploid nuclei The fusion of hyphae is called plasmogamy. The fused hyphae containing haploid nuclei from two individuals is heterokaryotic. In some cases, plasmogamy results in cells with one nucleus from each individual. This condition is called dikaryotic. Two nuclei that originated from different individuals fuse to form a diploid zygote. Meiosis then produces either four haploid nuclei or four haploid cells.

YEASTS AND MOLDS Molds - multicellular Yeasts - unicellular The simplest form of growth is budding. Buds are called blastoconidia. Seen in yeasts.

..Reproduction in yeast

YEASTS AND MOLDS © CDC/ Dr. Edwin P. Ewing, Jr.

The life cycle of Rhizopus stolonifera ( bread mold).   .  

….Reproductive structures in Breadmold   ….Reproductive structures in Breadmold .  

Classification of Fungi By Reproductive Structures (PG 312) Oomycetes Water Molds Motile sexual spores Example: Potato blight Phytophthora

…..Classification of Fungi Zygomycetes Unenclosed zygospores produced at ends of hyphae Example: Black bread mold Rhizopus Ascomycetes Ascospores are enclosed in asci (sac-like structures) at the ends of hyphae or yeasts Examples: Penicillium, Saccharomyces

..Zygomycota Conjugation Fungi

…..Classification of Fungi Basidiomycetes Basidiospores are produced on a club-shaped structure called a basidium Example: Mushrooms, Cryptococcus Deuteromycetes “Imperfect fungi” No sexual stage is known for these fungi Many parasitic fungi fall into this class Examples: Candida, Epidermophyton

CLASSIFICATION OF PATHOGENIC FUNGI Fungal diseases are classified into 4 groups: Superficial mycoses Mucocutaneous mycoses Subcutaneous mycoses Deep mycoses

SUPERFICIAL MYCOSES Fungal infections that do not involve a tissue response: Piedra – colonization of the hair shaft causing black or white nodules Tinea nigra – brown or black superficial skin lesions Tinea capitis – folliculitis on the scalp and eyebrows

…SUPERFICIAL MYCOSES Favus – destruction of the hair follicle. Pityriasis – dermatitis characterized by redness of the skin and itching: Caused by hypersensitivity reactions to fungi normally found on skin Mostly seen in immunocompromised patients.

CUTANEOUS AND MUCOCUTANEOUS MYCOSES Associated with: Skin Eyes Sinuses Oropharynx and external ears Vagina

…CUTANEOUS AND MUCOCUTANEOUS MYCOSES Ringworm – skin lesions characterized by red margins, scales and itching: Classified based on location of infection Tinea pedis – on the feet or between the toes Tinea corporis – between the fingers, in wrinkles on the palms Tinea cruses – lesions on the hairy skin around the genitalia Tinea capitis – scalp and eyebrows Onychomycosis – chronic infection of the nail bed Commonly seen in toes Hyperkeratosis – extended scaly areas on the hands and feet

..CUTANEOUS AND MUCOCUTANEOUS MYCOSES www.doctorfungus.org

…CUTANEOUS AND MUCOCUTANEOUS MYCOSES Mucocutaneous candidiasis – colonization of the mucous membranes Caused by the yeast Candida albicans Often associated with a loss of immunocompetence Thrush – fungal growth in the oral cavity An indicator of immunodeficiency. Vulvovaginitis – fungal growth in the vaginal canal Can be associated with a hormonal imbalance

SUBCUTANEOUS MYCOSES Localized primary infections of subcutaneous tissue: Can cause the development of cysts and granulomas. Provoke an innate immune response - eosinophilia.

…SUBCUTANEOUS MYCOSES There are several types: Sporotrichosis – traumatic implantation of fungal organisms Paranasal conidiobolae mycoses – infection of the paranasal sinuses Causes the formation of granulomas. Zygomatic rhinitis – fungus invades tissue through arteries Causes thrombosis Can involve the CNS.

DEEP MYCOSES Deep mycoses Usually seen in immunosuppressed patients with: AIDS Cancer Diabetes Can be acquired by: Inhalation of fungi or fungal spores Use of contaminated medical equipment Deep mycoses can cause a systemic infection – disseminated mycoses Can spread to the skin

..DEEP MYCOSES www.doctorfungus.org

..DEEP MYCOSES Coccidiomycoses – caused by genus Coccidioides Primary respiratory infection Leads to fever, erythremia, and bronchial pneumonia Usually resolves spontaneously due to immune defense Some cases are fatal

…DEEP MYCOSES Histoplasmosis – caused by Histoplasma capsulatum Often associated with immunodeficiency Causes the formation of granulomas Can necrotize and become calcified If disseminated, histoplasmosis can be fatal.

..DEEP MYCOSES © CDC/Susan Lindsley, VD

…DEEP MYCOSES Aspergillosis – caused by several species of Aspergillus Associated with immunodeficiency Can be invasive and disseminate to the blood and lungs Causes acute pneumonia Mortality is very high. Death can occur in a matter of weeks.

Common Fungal Diseases Additional Information to read: Candidiasis Dermatomycoses Respiratory Fungal Infections

Candidiasis Cause: Candida albicans Dimorphic fungus of the class Deuteromycetes Grows as yeast or pseudohyphae Spread by contact; often part of normal flora Opportunistic infections common Vulvovaginitis Oral candidiasis (thrush) Intestinal candidiasis

Dermatomycoses Dermatomycoses are any fungal infection of the skin or hair. Caused by many different species and are generally named after the infected area rather than the species that causes it. Dermatomycoses are one of the most frequent sources of lesions on the skin.

…Dermatomycoses Cause: Several genera of dermatophytic fungi Trichophyton, an ascomycete Microsporum, an ascomycete Epidermophyton, a deuteromycete Grow on skin, hair, nails Transmitted by contact with infected persons or animals

…Dermatomycoses Tinea is a fungus that can grow on your skin, hair or nails. As it grows, it spreads out in a circle, leaving normal-looking skin in the middle- look like a ring. At the edge of the ring, the skin is lifted up by the irritation and looks red and scaly. To some people, the infection looks like a worm is under the skin. Because of the way it looks, tinea infection is often called "ringworm." no worm under the skin!! Pictures!!!!

….Dermatomycoses Tinea infections: Red, scaly or blister-like lesions; often a raised red ring; “ringworm” Tinea pedis Tinea corporis Tinea capitis Tinea favosa Tinea barbae Tinea cruris Tinea unguium

Respiratory Fungal Infections Cryptococcosis Cryptococcus neoformans A yeast of class Basidiomycetes Soil; esp. contaminated with bird droppings Airborne to humans Gelatinous capsules resist phagocytosis Respiratory tract infections Occasional systemic infections involving brain & meninges

…. Respiratory Fungal Infections Histoplasmosis Histoplasma capsulatum, an ascomycete Airborne infection Transmitted by inhalation of spores in contaminated spores Associated with chicken & bat droppings Respiratory tract symptoms; fever, headache, cough, chest pains

….Respiratory Fungal Infections Blastomycosis Blastomyces dermatitidis, an ascomycete Associated with dusty soil & bird droppings Skin transmission: via cuts & abrasions Raised, wart-like lesions Airborne transmission: via inhalation of spores Respiratory tract symptoms Occasional internal infections with high fatality rate

References http://www.microbiologybytes.com/introduction/myc2.html Microbiology, A clinical Approach -Danielle Moszyk-Strelkauskas-Garland Science 2010 http://en.wikipedia.org/wiki/Scientific_method https://files.kennesaw.edu/faculty/jhendrix/bio 2261/home.html http://www.cdc.gov/cmv/ Lecture PowerPoints Microbiology Principles and Exploration 7th edt. J G Black ; J Wiley Pub. http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb2pg21.htm http://www.hcs.ohio-state.edu/hcs300/fungi.htm http://www.microbiologybytes.com/introduction/myc2.html