Fungi, Parasites, and Diseases

FUNGI, PARASITES, AND DISEASES

• Fungi are a diverse group of organisms with unique characteristics that differ from plants, animals, and bacteria.
• Fungi have eukaryotic cells with a true nucleus and membrane-bound organelles.
• Fungi have a rigid cell wall made of chitin.
• Fungi are heterotrophs, obtaining nutrients by absorbing organic compounds from their surroundings. Many are decomposers.
• Fungi reproduce both sexually and asexually. Asexual reproduction uses spores, and sexual reproduction involves gametes or fusion of hyphae.
• Fungi have a filamentous structure called hyphae, which form a mycelium. The mycelium is the main body of the fungus and involved in nutrient absorption.
• Fungi can be saprophytic (obtaining nutrients from dead or decaying matter) or parasitic (obtaining nutrients from living hosts).
• Fungi are important in ecosystems, acting as decomposers and forming mutualistic relationships with plants (mycorrhizae).

EUKARYOTIC PARASITES

• Eukaryotic parasites belong to the Domain Eukarya and live in or on a host organism.
• They obtain nutrients from the host and can cause harm.
• Eukaryotic parasites are more complex than prokaryotic parasites (having a true nucleus and membrane-bound organelles).
• Eukaryotic parasites often have complex life cycles with various stages, potentially involving vectors (e.g., mosquitoes, ticks) or contaminated food/water for transmission.
• Examples of eukaryotic parasites include protozoa, helminths (worms), and some fungi.

PROTISTS

• Protists are a diverse group of eukaryotic microorganisms that do not fit into plant, animal, or fungal categories.
• They are a paraphyletic group meaning they do not share a common evolutionary ancestor.
• Protist cells have a true nucleus and membrane-bound organelles.
• Protists exhibit a variety of shapes, motilities, and nutritional strategies.
• They can be unicellular, colonial, or multicellular. Some protists are microscopic; others are macroscopic.
• Protists lack specialized tissues and organs.
• Many protists are capable of movement using structures like flagella, cilia, or pseudopodia.
• Protists can be heterotrophic (obtaining nutrients from other organisms) or autotrophic (producing their own food through photosynthesis).
• Protists can reproduce asexually (through binary fission, multiple fission, or budding) or sexually.
• Some protists have cell walls composed of various materials—cellulose, silica, chitin, or others.
• Protists play several crucial roles in various ecosystems as primary producers, decomposers, and as components of the food web.
• Some protists cause diseases in plants, animals, and humans.

HELMINTHS

• Helminths are parasitic worms that belong to the Phylum Platyhelminthes (flatworms) or Nematoda (roundworms).
• They infect humans and other animals.
• Helminths are multicellular, unlike some parasites (bacteria or protozoa).
• Helminths have eukaryotic cells.
• Helminths have bilateral symmetry.
• Helminths typically have specialized tissues and organs.
• Many helminths have complex life cycles, involving different stages (e.g., eggs, larvae, adult forms), potentially in multiple hosts, for transmission.
• Some are hermaphroditic (having both male and female reproductive organs), while others are dioecious (with separate male and female individuals).
• They can cause diseases in humans such as intestinal worms, filarial worms, and liver flukes.
• Those worms have a tough, external cuticle.
• Helminths are parasitic meaning they live in or on a host organism, deriving nutrients from the host at the expense of the host.

FUNGAL DISEASES

• Fungi are often involved in various diseases
  • Athlete's foot (Tinea pedis) is a fungus infection that affects the skin of the feet. The signs of athlete's foot are itching, swelling, redness, and blisters.
  • Oral thrush is a fungus infection in the mouth, often presenting as white spots.
  • Candidiasis is a yeast infection, with symptoms including vaginal or genital redness, itchiness, and discharge. Other forms of candidiasis can affect various locations around the body.
  • Aspergillosis is a lung disease with diverse symptoms, varying from cough to fever.
  • Histoplasmosis is a lung disease involving the inhalation of spores.
  • Cryptococcosis affects lungs and the central nervous system presenting with various symptoms.
  • Prevention for fungal diseases involves avoiding contact with contaminated surfaces or people, maintaining hygiene, and treating infections promptly. In some cases, antifungal medications are needed.

PROTIST DISEASES

• Malaria is a blood disease caused by parasitic protozoa. Symptoms include shivering, fever, and sweating (episodes). Bites of infected mosquitoes transmit these parasites.
• Toxoplasmosis is a disease caused by the protozoan Toxoplasma gondii. Some infections are without symptoms. However, in immunocompromised people, symptoms can include fever, headache, confusion, and seizures. The infection can be passed from an infected cat to another organism or from a mother to a child before birth.
• Giardiasis is an intestinal infection causing diarrhea, gas, and abdominal cramps. It spreads through contaminated water or food sources.
• Amebiasis is an intestinal infection characterized by diarrhea containing mucus and blood, severe abdominal cramps, and low-grade fever (in some cases). This infectious disease is also known as amebic dysentery.
• African trypanosomiasis (sleeping sickness) is spread through insect bites and characterized by fever, headache, joint and muscle aches, and sometimes neurological issues.
• Chagas disease is caused by the parasite Trypanosoma cruzi; it has acute and chronic phases, can be passed between animals and humans, and affects the heart and intestine.
• Cryptosporidiosis is caused by the Cryptosporidium parasite and is characterized by infection of the guts, diarrhea, nausea, fever, and stomach cramps.
• Prevention involves avoiding contaminated water and food, avoiding contact with contaminated surfaces, and using appropriate methods for treating infected individuals.

PARASITIC WORMS

• Ascariasis (caused by Ascaris lumbricoides): Asymptomatic or mild infection can involve pain, nausea, and diarrhea. Transmission is fecal-oral via contaminated food or hands, especially with poor sanitation. Diagnosis involves microscopic examination of feces. Prevention involves proper sewage management and hygiene. Treatment often involves medications (e.g., Albendazole, Mebendazole).
• Trichuriasis (caused by Trichuris trichiura): Similar to ascariasis, this parasitic infection presents with symptoms such as abdominal discomfort, diarrhea, and anemia when severe; transmission is via contaminated soil/food; prevention includes improved sanitation, hygiene, and access to clean water.
• Necatoriasis (caused by Necator americanus): This parasitic infection causes few symptoms unless heavy worm load occurs. transmission is via skin penetration by larvae through bare feet. Diagnosis often relies on microscopic identification of eggs in stools; treatment commonly involves medications such as Albendazole or Mebendazole. Prevention is primarily related to sanitation and wearing appropriate footwear..
• Enterobiasis (caused by Enterobius vermicularis): Common worm infection causing itchy anus, disturbed sleep, or teeth grinding. Transmission involves ingestion of eggs that stick to hands/surfaces; diagnosis through tape adhesion tests; treatment typically involves Pyrantel pamoate, for the whole household if one person is diagnosed.
• Schistosomiasis (caused by Schistosoma): Characterized by itching, fever, cough or muscle aches in some cases, the infection involves contact with contaminated freshwater. Diagnosis involves microscopy or molecular and antibody tests; prevention involves avoiding contact with water sources or improved sanitation. Treatment often involves medications (Praziquantel).
• Taeniasis (tapeworm infection): This infection can be asymptomatic. However, the worms can be found in the intestines causing discomfort, weight loss, or diarrhea. Transmission is via contaminated food. Individuals need to carefully cook foods consumed so eggs or proglottids are destroyed.
• Cystic echinococcosis(caused by Echinococcus granulosus): Mild symptoms such as pain, diarrhea and nausea can be present. Prevention involves avoiding contact with infected dogs or contaminated environments; diagnosis through ultrasound, CT, or MRI (to view the cysts). Treatment usually involves surgery and medicines such as Albendazole.
• Alveolar echinococcosis(caused by Echinococcus multilocularis): This parasitic infection presents with slow-growing, tumor-like lesions in the liver; prevention involves controlling fox populations, avoiding contact with contaminated environments and proper hygiene. Diagnosis entails ultrasound, CT, MRI, and antibody tests. Treatment involves surgical interventions and medication like Albendazole.
• Filariasis (caused by Wuchereria bancrofti or similar species): Filariasis has an acute stage characterized by fever, swelling in the limbs, sometimes skin lesions. Often asymptomatic. In its chronic stage, the disease is characterized by elephantiasis and hydrocele; prevention involves control of mosquitos, insect repellents, and prophylactic medication. Treatment involves medications such as diethylcarbamazine (DEC), Ivermectin, or others.