BM1022 Fungi and parasites PDF

BM1022 Survey of the Microbial World: fungi and parasites Dr Jeff Warner A/Professor Microbiology...

BM1022 Survey of the Microbial World: fungi and parasites Dr Jeff Warner A/Professor Microbiology Biomedicine College of Public Health, Medical and Veterinary Sciences Room 87-004 Tel: 47816375 [email protected] Survey of the Microbial World: Fungi and parasites L&B Ch 6 Learning objectives What are the characteristics of eukaryotic cells Properties of characteristics of fungi, protozoa and helminths Examples of diseases caused by eukaryotic organisms  Fungi and parasites Eukaryotes – similar to us! Survey of the Microbial World: Fungi and parasites Eukaryotes More advanced, complex More similar to animals than bacteria and viruses Major causes of morbidity and mortality - particularly in the developing world  Survey of the Microbial World: Fungi Larger and more complex than bacteria Obtain energy from organic matter – Heterotrophic by absorption Filamentous fungi (moulds) – Produce spores – airborne – Can cause allergies or instigate infection Survey of the Microbial World: Fungi Unicellular fungi (yeasts) Both can cause serious disease Mostly superficial infections – Skin – Mucous membranes Many antibiotics are derived from fungi Require warm, moist, organic rich environment Normal flora in low numbers  Fungal Infections: superficial Tinea versicolor Malassezia furfur – a yeast Patchy discolouration In the tropics – Sweat Moisture Dead cells – organic matter – Constant high temp  Fungal Infections: superficial Tinea imbricata Trichophyton concentricum – Concentric circle PNG children – History of malnutrition / malaria  Fungal Skin Infections: cutaneous Tinea pedis (athlete’s foot) Epidermophyton spp – Sweating feet inside shoes – Dry, scaly lesions – Secondary infection common Tinea corporis (trunk / non-hair bearing) “ringworm” – it is not a worm! – Raised annular lesions Trichophyton spp – Classic tinea – Immunocompromised – Moist, organic rich regions  Fungal Infections: cutaneous Candidiasis Candida albicans – Thrush - mucous membranes – Broad spectrum antimicrobial therapy Kills normal, protective flora – Secondary cutaneous infection from tinea  Fungal Infection: systemic Meningitis: fungal Cryptococcus neoformans – 90% fatal – Slowly progressive / chronic disease – Relationship with Eucalyptus camaldulensis – pigeon droppings – Affects immunocompromised – Marker disease for AIDS  Fungal Infection: control strategies? Fungi like moist, warm and organic rich environments Decrease them! – Hygiene – Open shoes Fungi infect opportunistically Maintain general good health! – Diet – Limit predisposing behaviour – grog, smoke etc  The parasites Understanding lifecycles, helps in their control Living at the expense of another: defines a relationship (see later) Parasite life cycles potentially complex many hosts or vectors Definitive host = host where sexual reproduction occurs Intermediate host = host where immature forms develop before sexual maturity Vectors enable dispersal of parasite in dispersed host populations, usually flying insect  Eukaryotic Parasites: Protozoa Phylum Sarcomastigophora – Subphylum Sarcodina (amoebae ) – Subphylum Mastigophora (Flagellates) Phylum Ciliophora (ciliates) Phylum Apicomplexa / Sporozoa (mostly non-motile) Phylum Microspora (tiny intracellular parasites – classification problematic)  Eukaryotic Parasites: helminths Phylum Aschelminthes – Class Nematoda (nematodes, the round worms) Phylum Platyhelminthes (flatworms) – Class Trematoda (flukes) – Class Cestoda (tapeworms Phylum Nematomorpha (horse hair worms) – Marine parasites Phylum Acanthocephalus (thorny headed worms) – Insects and insect eaters Phylum Annelida (true segmented worms) – Leeches, earth worms  Eukaryotic Parasites Protozoa – Phylum Apicomplexa / Sporozoa – Plasmodium spp causes malaria – Requires anopheles mosquito for reproduction and transmission – Causes red cell destruction anaemia – One species cause microcirculation occlusion Lack of blood to brain tissue Death – Understanding lifecycles important for control Life Cycle of Malaria parasite  Eukaryotic Parasites Protozoa – Subphylum Mastigophora (Flagellates) – Trichomonas vaginalis – Motile, flagellate – Sexually transmitted – Asymptomatic in males – Produces vaginitis in women  Eukaryotic Parasites Protozoa. – Subphylum Mastigophora (Flagellates) Giardia lamblia (intestinalis) – Causes diarrhoea – Two stages in lifecycle Motile, invasive Dormant cyst Life Cycle of Giardia lamblia  Eukaryotic Parasites Protozoa – Phylum Apicomplexa / Sporozoa Toxoplasma gondii Toxoplasmosis – Parasite of cats and related animals – Oocysts transmitted to humans via cat faeces – Transplacental migration – Drastic affects on foetus – Congenital toxo: Retardation Blind Deaf Life cycle of Toxoplasma gondii  Eukaryotic Parasites Helminths – Human to human – Class Nematoda (nematodes, the round worms) elongated unsegmented worms Enterobius vermicularis – Pinworm – Common in children – Simple lifecycle Life Cycle of Pinworm  Eukaryote parasites Dog hookworm – accidental animal to human – Class Nematoda (nematodes, the round worms) Ancylostoma caninum Cutaneous or dermal larval migrans – Human not definitive host – Infective larvae penetrate skin – 2nd stage lavae migrate – Allergic sequlae  Helminths Ascaris lumbricoides – human - environment - human – GIT symptoms – Bowel / biliary obstruction – Pneumonia - eosinophilic – Non-humans definitive host species – Tissue migration - visceral migrans Diagnosis Ova 55-75 x 35-50um Occasionally patients pass adults  Eukaryotic parasites Helminths – animal reservoir required to transmit to human – Platyhelminths – Class Cestoda (tapeworms) – Attach by means of hooks and suckers Taenia solium – Pig tapeworm Pig intermediate host – Undercooked infected pork – Adults 4 – 8m – Cysticercosis Eukaryotic parasites  Parasitic Infection: control strategies? If a vector is involved Eliminate vector! Faecal oral transmission Prevent faecal contamination! – Waste hygiene – Animal (cats!) – Humans Parasite infects tissue we consume? Meat inspection / cook meat well!