Parasites and Prions - Basic Science Core

Medical Microbiology

Three Types of Parasites

1) Protozoa

2) Helminths (worms)
3) Ectoparasites

Protozoa

• single-celled organisms that can multiply inside the host

Helminths

• multi-cellular organisms often visible to the naked eye in their adult stage

Ectoparasites

basically insects that live on the skin’s surface, feeding on blood, body fluids or tissue (dead skin cells)

Types of Protozoa (4)

1) Giardia

2) Plasmodium

3) Toxoplasma gondii

4) Cryposporidiosis

Giardia

• A Protazoa

• Causes GIARDIASIS

• Lives in the intestines of infected people and animals and comes out of the body in the feces

• It can survive for weeks to months outside the body (e.g., soil).

• Short-term symptoms include:

  • Diarrhea, stomach cramps, gas and nausea (2 to 5 times a day)

  • Smelly, greasy feces that float

  • Dehydration (loss of fluids

Malaria

• A Protazoa

• Caused by Plasmodium parasites Plasmodium falciparum and Plasmodium vivax

• Transmitted to humans through bites of infected female Anopheles mosquitos

• Early symptoms resemble the flu (fever, chills, headache, fatigue) and cause jaundice, seizures, come and severe anemia

• Treatment involves anti-malarial medications, but prevention with insect repellant and antimalarial medication is best

Toxoplasmosis

• A Protazoa

• Caused by Toxoplasma gondii Contracted eating undercooked meat, drinking contaminated water or exposure to cat feces

• Most healthy individuals experience no symptoms, but flu-like symptoms are possible

• PREGNATE WOMEN CAN HAVE A MISSCARAGE!

Cryposporidiosis

1) Contaminated by taco bell lettuce

2) Watery diarrhea, dehydration, stomach cramps, nausea, fever

• A Protazoa

Types of Helminths (3)

1) Nematodes (Roundworm)

2) Trematodes (Flukes)

3 Cestodes (Tapeworms)

Nematodes

• Roundworms

• have a cylindrical body and generally infect the intestines

• Helminths, Transmitted by the bottom/top route

• Blood in diaharia, abdominal Pain, weight loss

Trematodes

• Flukes

• Have a flat body and leaf-shaped head with a sucker that helps them attach to tissue and infect the bile ducts, liver and blood

• Helminths, Transmitted by the bottom/top route

• Blood in diaharia, abdominal Pain, weight loss

Cestodes

• Tapeworms

• Are long, segmented flatworms that infect the intestines

  Helminths, Transmitted by the bottom/top route

• Blood in diaharia, abdominal Pain, weight loss

Medications For Helminths (2)

1) Albendazole

2) Mebendazole

Types of Ectoparasites (3)

1) Pediculosis (lice)

2) Scabies

3) Bed Bugs

Pediculosis Types (3)

• Lice

• Three Types

• 1) Pediculosis capitis (head louse 🡪 hair and scalp [B])

  2) Pediculosis corporis (body louse 🡪 trunk [C])

  3) Pediculosis pubis (crab louse 🡪 pubic hair [A])
  

Pediculosis capitis

• Headlice

• Direct contact with head of an infested person is generally considered the primary mode of transmission

• HEAD LICE CANNOT FLY OR JUMP

• Lifespan approx. 1 month; female lays 7-10 eggs (nits)/day, cementing them firmly to the base of a host hair; eggs hatch in 7-8 days ……then it’s time to feed!

• Treatment →

  • Topical pediculicide

• Mechanical removal of lice by wet combing

• Mechanical removal of nits from hair (good lighting and a special nit comb are a must

• Shave Hair

Permethrin & Pyrethrin (piperonyl butoxide)

Neuro Toxin Treatments for head lice and public lice

• Permethrin 1% is for lice

• Permethrin 5% is for Scabies

Pediculosis corporis

• Lice on the body

• Direct contact with head of an infested person is generally considered the primary mode of transmission

• Kill them by washing and bathing alot or medication

• symptoms are primarily itching

• Treatment

  • Topical pediculicide

Pediculosis pubis

• Otherwise known as crabs, this is pubic lice

• Direct contact with either a person with it or a towel used by someone with it is the primary mode of transmission

• Treatment →

  • Topical pediculicide

How to primarily treat the Pediculosis Types with medication

• Topical Pediculicide

• For Head Lice & Pubic Lice 1% Permethrin

Sarcoptes scabiei

• This is another word for scabies

• Scabies can affect anyone and can be common in

  areas of poor sanitation, poverty and overcrowding

• Females burrow into the epidermis and lay eggs

  which mature in 10-14 days

• Transmission of scabies is usually from person to

  person by direct contact.

• The essential lesion is a small, erythematous,

  nondescript papule, often excoriated and tipped with

  hemorrhagic crusts

Sarcoptes scabiei Treatment

Treatment 🡪 Topical scabicides

• 5% (not 1% as for head lice) permethrin cream

  (Elimite)

• Oral ivermectin

Bed Bugs

1) Bed bugs are small, reddish-brown, wingless insects that

feed on the blood of humans and animals.

2) Bed bugs prefer to hide in cracks and crevices near where

people sleep, such as in mattresses, box springs, bed

frames, and furniture.

3) Very good at hitch hiking

4) Bed bugs feed on blood, usually at night while people are

sleeping

5) Treatment is get pest control

Prions

• misfolded versions of a normal cellular protein called PrPC (Prion Protein Cellular).

• Misfolding leads to the formation of an abnormal, infectious form called PrPSc (Prion Protein Scrapie).

• All prion diseases affect the nervous system and are always fatal

Types of Prion Diseases (6)

1) Creutzfeldt-Jakob disease (CJD)

2) Variant Creutzfeldt-Jakob disease (vCJD)

3) Kuru

4) Scrapie

5) Bovine spongiform encephalopathy (BSE)

6) Chronic wasting disease (CWD): Affects deer, elk, and moose

1) Creutzfeldt-Jakob disease (CJD)

The most common human prion disease, with sporadic, inherited, and acquired forms

• Kids who received hGH from cadaver pituitaries developed CJD

Variant Creutzfeldt-Jakob disease (vCJD)

A form of CJD linked to the consumption of prion-contaminated beef from cattle with bovine spongiform encephalopathy (BSE)

Kuru

A prion disease primarily found in Papua New Guinea, transmitted

through ritualistic cannibalism

Scrapie

A prion disease affecting sheep and goats

Bovine spongiform encephalopathy (BSE)

Also known as "mad cow disease," it affects cattle

Chronic wasting disease (CWD)

Affects deer, elk, and moose