Malaria and Snail Fever Overview

Malaria

• Caused by 5 species of protozoa
• Protozoa have a complex indirect life cycle
• Anopheles mosquitoes are vectors and definitive hosts
• Malaria is horizontally transmitted by blood transfusions
• Malaria is vertically transmitted via sequestration of parasites in the placenta
• Common in sub-Saharan Africa, previously worldwide
• Immunity (premunition) can develop in endemic areas
• Emerging vaccines and antimalarial drugs exist
• Symptoms typically develop 10-15 days after infected mosquito bite; can be delayed months
• Causal Agent: Plasmodium Falciparum
• Type of Organism: Protozoan
• Most Prevalent Region: Sub-Saharan Africa
• Transmission: Biological Vector
• Definitive Hosts: Mosquitoes
• Intermediate Hosts: Humans, Primates
• Infected Tissues/Organs: Red blood cells
• Symptoms: Fever, chills
• Primary Avoidance: Prophylaxis, bugspray

Snail Fever (Human Schistosomiasis)

• Caused by flukes
• Transmission in humans is by direct penetration
• Complex life cycle with snails as intermediate hosts
• Most infections in sub-Saharan Africa
• Estimated global prevalence of 82 million people
• Humans can develop immunity
• Some species cause swimmer's itch, a non-contagious Michigan disease
• Causal Agent: Schistosomes
• Type of Organism: Fluke
• Most Prevalent Region: Africa and Brazil
• Transmission: Direct penetration
• Definitive Hosts: Humans
• Intermediate Hosts: Freshwater snails
• Infected Tissues/Organs: Liver, bladder
• Symptoms: Fever, chills, headache, itching
• Primary Avoidance: Stay out of water with schistosomes

Human Threadworm Disease (Strongyloidiasis)

• Caused by human threadworm
• Type of Organism: Nematode
• Most Prevalent Region: Tropical and subtropical areas
• Transmission: Direct penetration
• Definitive Hosts: Humans
• Intermediate Hosts: None
• Infected Tissues/Organs: Large intestine
• Symptoms: None
• Primary Avoidance: Avoid infected soil, wear shoes

Trichinosis

• Caused by a nematode (trichina worm)
• Transmission is trophic
• Simple (direct) life cycle, unusual as definitive hosts serve as intermediate hosts
• Muscle cells are invaded causing myofibrils to break down; juveniles are encapsulated
• Capillary network surrounds muscle cell, creating a nurse cell
• Common worldwide
• Man is an accidental host, primarily through consuming infected carnivore meat
• Causal Agent: Trichina worm
• Type of Organism: Nematode
• Most Prevalent Region: Cosmopolitan
• Transmission: Trophic
• Definitive Hosts: Pigs, rats
• Intermediate Hosts: Pigs, rats
• Infected Tissues/Organs: Small intestine and striated muscle cells
• Symptoms: Fever
• Primary Avoidance: Don't eat undercooked meat, especially game

Hookworms

• 2017 study found 34% of participants suffering from hookworm, a parasitic infection contracted by walking barefoot on contaminated soil or fecal matter
• Hookworms are species-specific; cannot be identified just by eggs
• Can cause cutaneous larva migrans (ground itch) in humans, but mature in other animals
• Live in small intestine, attached to villi and feed on blood and tissue
• Severe infections: up to 200mL of blood loss per day
• Causal Agent: Hookworms
• Type of Organism: Parasites
• Most Prevalent Region: Worldwide
• Transmission: Fecal-oral, and direct penetration
• Definitive Hosts: Humans
• Intermediate Hosts: None
• Infected Tissues/Organs: Small intestine, attached to villi (feed on blood and tissue)

Giant Intestinal Roundworms

• Trypsin (proteolytic enzyme) breaks down proteins in small intestine. Worms excrete anti-trypsin
• Symptoms: appetite loss, impaired weight gain, growth/cognitive impairment,
• Can cause difficulty breathing and fever as larvae migrate through the lungs, or abdominal discomfort, distension, nausea, and diarrhea when adults settle in the small intestine.

Whipworms

• Human whipworm causes constant urge to defecate, sometimes with prolapse
• Diagnosed by finding eggs in stool sample
• Eggs can be hard to find in light infections; a concentration procedure is recommended
• Prevention: Avoid ingesting soil with human feces. Wash hands, wash, peel, or cook vegetables before eating
• Causal Agent: Parasitic worms
• Type of Organism: Nematodes
• Most Prevalent Region: Subtropical/tropical climates
• Transmission: Fecal-oral, and direct penetration
• Definitive Hosts: Humans, Intermediate hosts: None

Freshwater Ich (white spot disease)

• Protozoan parasite causing "white spot disease" in freshwater fish
• Highly contagious, obligate parasite
• Life cycle: Trophont (attaches to fish; resistant to treatment), Tomont (develops in cysts; not treatable), Theront (free-swimming and treatable stage)
• Symptoms: White spots, lethargy, gasping, and sudden death
• Treatments: Copper sulfate and formalin, Regular dosing to target theronts; removal of debris and dead fish
• Prevention: Quarantine new fish, maintain water temperature, reduce stress

Crypto Disease

• Waterborne protozoan causing cryptosporidiosis
• Protozoan life cycle: Oocysts that survive outside the host and are resistant to disinfectants.
• Transmission: Fecal-oral route, contaminated water/food, or direct contact
• Symptoms: Watery diarrhea, dehydration, nausea; severe in immunocompromised
• Treatment: Rehydration therapy, Nitazoxanide (less effective in immunocompromised) - Prevention: Avoiding untreated water, maintaining hygiene, and boiling water if suspected contamination

Pubic Lice (Pediculosis)

• Primitive parasite infecting coarse hair, spread primarily via direct, sexual contact
• Life cycle: Egg(Nit)- hatches in 6-10 days. Nymph- feeds on blood, matures in 2-3 weeks; and Adults - lives 3-4 weeks, dies without a host in 24-48 hours.
• Symptoms: Itching, small red/blue spots, yellow/white dots on hair, crusty eyelashes.
• Treatments: Over-the-counter lotions (permethrin, pyrethrins). Hair removal ineffective.
• Prevention: Practice safe sex, avoid sharing bedding or clothing
• Habitat: Found worldwide; infects humans only.

Explore the key aspects of Malaria and Snail Fever, including their causes, transmission methods, and prevalent regions. Understand the life cycles of the parasites involved and the symptoms associated with these diseases. This quiz provides insights into prevention and current medical advancements.