Module 3: Other Parasites & Their Role In Nature and Human Health

Invertebrates

• Animals that lack a column (backbone).

• Most abundant on the planet.

Exoskeleton

Arthopods

Hydrostatic Skeleton

Annelids and chiarians

Shells

Mollusk

Hymenoptera

• Diverse order containing ants, bees, wasps, and sawflies.

  • Includes the parasitod wasp and the Asian Giant Hornet

Tree of Life

• Many approaches to describe life.

  • Included in Mayan antiquity, Darwin, and Linnaeus

Authority

• Whoever first names and describe a species.

DNA Barcoding

• Method that identifies and classifies living species using a short section of DNA.

Steps of DNA Barcoding

1. Extract DNA

• DNA is extracted from numerous sources.

• Environmental DNA (eDNA) contains numerous of species samples.

2. Denature: breaks bonds

3. Anneal: primers bond to the complementary sequence

4. Elongation: Taq polymerase builds a new DNA strand

Cytochrome Oxidase (COI) Gene role in DNA Barcoding

• Cytosome oxidase (COI) gene is used to help identify. Gene is conserved over many species becuse of the mitochrondrial genome. Primers prime to the complementary sequence.

How To Collect Ticks

• Sticky traps + CO₂

• Flagging

Chagas Disease

• Caused by a trypanosome - endemic to the Americas

• Vectored by an arthropod

• Zoonotic

• Named after Dr. Charles Chagas

Acute Symptoms of Chagas Disease

• Can range from asymptomatic and fatal.

• Flu-like symptoms

• Detectable in blood parasitemia smear

  • More parasites → worse outcome

Chronic Phase of Chagas Disease

• Last a lifetime

• 70% of cases were asymptomatic

• Inflammatory responses

  • Heart, colon, esophagus

• No cure or vaccine

How does Trypanosoma cruzi infect?

• Tricks the immune system

• Can enter through phagocytosis by macrophages.

• The parasite can live in spleen, lymph, cardiac, and smooth muscle cells.

  • Muscles, skeletal muscle, placenta.

Reservoir Mammals

• Can be infected by eating infected animals.

• Harbors a specific pathogen or parasite over a long period without being affected.

Transmission of Trypanosomes

• Trypanosomes are injested by triatomine bug (ex. Kissing Bug).

  • Kissing bug feces can enter through the bite, allowing the parasite to enter.

  • Inside the bug’s gut, the parasite multiplies; fission occurs, and it becomes slender epimastigotes.

• Contamintaed Food

• Blood transfusions

• Mother → Child

Diagnosis of Chagas Disease

• PCR Analysis - DNA Barcoding

• Clinical Approach: Blood smears, examining lymph, tissues, cerebrospinal fluid.

• Immunodiagnostic Test: Testing antigens

  • Risk: can give a false positive/negative

Spread of Chagas Disease

• Endemic throughout in Latin America and Southern tier of North America.

• Although Chagas has been found everywhere.

Malaria

• Disease caused by the Plasmodium genus.

Human Pathological Importance for Malaria

• P. vivax

• P. falliparum

• P. malariae

Diagnosis of Malaria

• DNA

• Blood Smear from Host

Symptoms of Malaria

• Anemia

• Paraxysm - extreme shivers.

• Chills and fever

• Metabolic acidosis

• Cerebral complications

Distribution of Malaria

• Southern North America

• South America

• Africa

• Southern Parts of Asia

• Mosquito infects human by injecting saliva

• Infected sporozoites travel to the liver.

• Sporozoites asexually reproduces (schizogony)

• Merozoites form and are released to RBCs underfoes schizogony

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African Sleeping Sickness

• Caused by trypanosoma brucei

• Vectored by the tsetse fly

Why are some trypanosome lack functional Krebs Cycle?

• Trypanosomes that infects mammals live in the bloodstream.

• The bloodstream provides sufficient energy sources.

• Functional Krebs cycle and cytochrome chains are not necessary.

Tabanindae

• Family of flies that feed on blood.

• Diachlorus ferrugatus

  • Yellow or doctor fly

  • Found near water

  • Causes welts and irritation.

What are good characteristics of insect traps?

• Attracts host - seeking flies

• Entice flies

• Direct flies - hard to escape

Dematobia hominis

• Human Bot Fly

• Common in Mexico and S. America

• Forest biting fly - develops in the skin of mammals.

• Blue color

• Bot fly delivers eggs → female mosquito → bites human → eggs released → larvae develops in human.

Screw Worm

Cochliomyia hominivorax

• New World Species

• Obligate Parasite (needs to feed on living)

• Causes Nasopharyngeal myiasis

• Introduction of sterile flies can control the screw worms

  • Radiation → sterilizes

Trematodes

• Class of flatworms - platyhelminth phylum

• Flukes and trematodes

• Obligate Parasites

• Monogena and Digenea (most importance for human pathology)

• Ex. Schitosoma mansoni

Trematodes reproduce asexually in…

• The intermediate host - typically snails

Trematodes reproduce sexually in…

• Definitive host - vertebrates.

Lifecycle and Behavior of Trematodes

1. Miracidium: hatches from its shell and pentrates an immediate host.

• They are ciliated

2. Sporocyst: larva metamorphoses into a sac like sporocyst.

• Embryos develop. Have tails (motile)

3. Rediea: More differienated. Has a gut and pharynx

* 4. Cercaria: Has a tail to swim in water to find a host.

Morphology of Trematodes

• Suckers - anterior and ventral

  • Absorbs food through the skin

• Has both male and female reproductive organs

• Eats food - no anus for excretion

  • Waste is regurgitated

• Cerebral Ganglion: simple nervous system.

  • Ventral and lateral nerves.

Schistosomes

• Genus: trematodes (aka blood flukes)

• Parasitic flatworms

Lifecycle of Schistosoma

1. Mature flukes reside in the intestines

2. Fertilized eggs → water through human feces

3. Eggs develop into miracidia → infects snails

4. Develop into cercariae (asexual reproduction)

5. Enter the human skin → mature and sexually reproduces

Schistosomiasis

• AKA bilharzia

• Caused by S. mansoni

• Found throughout sub-Saharan Africa and the Americas

• Intermediate Host: Biomphalaria (aquatic snails)

• Reservoir Host: Baboons, Monkeys (Africa)

S. haematobium

• Prevalent in Africa and parts of the Middle East

• Intermediate Host: Bulinus

• Causes: urinary and urogenital schistosomiasis (FGS)

• Carcinogenic

Female genital schistosomiasis (FGS)

• Caused by the parasite S. haematobium

• Mimics STI pathology, but is not a STI

• Causes mucous lesions

• Negleted Tropical Disease

S. haematobium Clinical Impacts

• Swimmers itch at the infection site.

• Painful and bloody urination

• Anemia

• Inflammation and scarring of the bladder

• Lymph node enlargement

• Attacks on the liver and spleen

How can we apply the One Health Concept to Female genital schistosomiasis (FGS)?

• More funding is necessary to understand this disease and help the communities.

• Congress + Politicians → Mostly are men

• FGS is not concerning → mostly affecting women

• Gaps in the research, funding, and access.

Treatment of Schitosomas’s

• Avoid contact with contaminated water.

• Wear boots in swampy areas.

• Yearly treatment.

• Improve waste management (lantrines)

• Drug: praziquantel

• Avoid Stagnant Water → snails grow better here.

Arrival of S. mansoni

• Snail arrived before the split of Pangea.

• African schitosomiasis is prevalent recently → Atlantic Slave Trade brought the parasite to the Americas

• Snail Biomphalaria served as an intermediate host.

• Definitive host: humans

Apicomplexa

• Phylum: Apicomplexa

• Alveolate lineage

• Ex. Toxoplasmosis

Characteristics of Apicomplexa

• Apical Complex: attach, recognizes, and penetrates the host.

• Microtubules arranged spirally.

• Circular plasmid

• Microneme

• Rhoptries

Microneme

• Secretory glands attached to the moptries.

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Toxoplasmosis gondii

• Causes toxoplasmosis

• Mostly affects warm blooded animals

Transmission of toxoplasma gondii

• Definitive host: Cats. Contaminated feces.

• Intermediate Host: Humans → ingestion of infected oocysts containing the parasite.

Impacts of Toxoplasma gondii

• Alzheimer’s Disease

• Depression

• Schizophrenia

Amoeba

• Single celled eukaryotic cell.

• Protist

• Irregular shaped - moves through pseudopodia

• Amoebozoa: Entamoeba and Acanthamoeba

Naegleria fowleri

• “Brain-eating amoeba”

• Free-living

• Thrives in freshwater, rivers, and hotsprings.

• Goes up the nose → brain (Primary amebic meningoencephalitis)

• Fatal

• Use distilled water or boiled tap water.

Balamuthia mandrillaris

• “Brain eating amoeba”

• Lives in water, soil, and dust.

• Can infect the skin, brain, and organs

• Causes: granulomatous amoebic encephalitis

Water Mites

• Arachnids

• Group: Acari

• Parasitizes the species chironomids

  • eats copepods, mosquitoes larvae

• Found in freshwater environments

Integrated Pest Management

• Various ecological methods to manage pests within an habitat or environment.

• Chemical

• Mechanical

• Biological

Chemical Integrated Pest Management

• Pesticides and molluscicides

Biological Integrated Pest Management

• Biocontrol

• Ex., introduction of sterile organisms into the environment.

Mechanical Integrated Pest Management

• Collecting, traps, hand-picking, etc.

Prevention of Chagas Disease

• Clean-up litter and clutter from the yard and the house.

• Keep animals away from house.

• Sealing windows