Medical Parasitology Part 1

Microbio

Protista

Single cell

Metazoa (helminths)

large

Leishmania - disease of skin and digestive tract

can cause cutaneous or visceral infection

leishmaniasis

transmitted by sandflies of the genus phlebotomus

L. Major

cutaneous disease with ulcerative sores (prevalent on the eastern hemisphere)

L. Donovani

visceral leishmaniasis (kala azar)

prevalent in the old world

• Liver: diffuse fibrosis

Promastigote Stage

The infected stage (i)

Amastigote Stage

The diagnostic stage, Multiply in cells including macrophages of various tissues (d)

Protistan disease of the skin and GenitoUrinary Tracts

When present: Cyst - Dormant for and is the infectious stage (causes Disease)

Trophozoite: Actively feeding and pathogenic stage

Giardiasis - Giardia Intestinalis

Trans: Through food and water contaminated w/ sewage containing cysts

Trophozoites emerge and attach to intestinal lining

Symp: nausea, cramps, flatulence, diarrhea

Cryptosporidiosis

Intestines of mammals - acute, short-term infection

fecal oral route - immunocompromised individuals  

symp: self-limiting diarrhea, usuallys severe and often fatal 

Isolated in HIV?AIDS - positive pt presenting w/ diarrhea

Cyclosporiasis - Cyclospora Cayetanensis

Trans: Contaminated fresh produce and water

Symp: diarrhea, nausea, cramping, bloating, vom 

can last more than a month and can return later 

Amoebiasis - Entamoeba Histolytica

Cyst & Trophozoite

symp: amoebic dysentery

• blood, mucus visible in foul smelling stools, severe colitis

Trichomoniasis - Trichomonas Vaginalis

Res: Humans

about 70% asymptomatic, no cyst stage

Symp come and go, strawberry cervix

Men: itching/irritation in penis, buring urination/ejaculation

Women: itching, burning genitals, discharge can be white, yellow, greenish

can last months or even years

Balantidium Coli

rare in the US

only ciliate known to parasitize humans 

2 nuclei and reproduce by transverse binary fission, conjugation, autogamy, cytogeny 

2 contractile vacuoles

Res: Animals, esp. Swine (farm animals)

Malaria - Plasmodium species

disease of the liver and blood

anopheles mosquito

Plasmodium vivax (most common, can be latent and rare)

Plasmodium Falciparum (most dangerous) 

Also Ovale, and Malariae

Symp: fever, flu, rigors, headaches, sweats, tiredness, myalgia, diarrhea, slight jaundice, enlarged liver & spleen “blackwater” fever 

Life cycle of Plasmodium species

1, salivary glands - parasite develops

2. sporozoites - infective stage (infects liver

3. Merozoites - binds to red BC and gets infected

4. Gametocytes - what mosquito picks up

5. Micro-Macrogametocyte male and female

Malaria - clinical manifestations

Febrile Paroxysm

1 cold stage 2. hot stage 3. sweating 

Fever spikes will last 2 days for tertian malaria 

fever spikes will last 4 days for quartan malaria 

Black water (urine) fever - Plasmodium Falciparum

Acute intravascular hemolysis with hemoglobinuria

cycle and recovery around 48 hours

Babesia

Apicomplexan parasite (ticks)

causes malaria like disease 

Invades red BC causes Anemia, headache, occasional meningitis 

"Maltese cross” not seen with malarial parasites 

Babesiosis life cycle

tick → Gametocytes → sporozoites → humans → human to human trans through blood 

Trypanosoma parasites

can cause life threatening systemic disease

can cause african sleeping sickness (T. brucei)

tsetse fly 

chancre forms at site of bite 

invades bloodstream and then central nervous system 

Tryptophol = chem compound that induces sleep in humans

Two forms of African sleeping sickness: West

progress slowly, after 1-2 years of infection, parasite crosses blood brain barrier and infects CNS, people rarely live longer than 6-7 years and usually die around year 3

Two forms of African sleeping sickness: East

progress rapidly, large chancer sore, after few weeks of infection parasite will invade CNS, death within months 

American Trypanosomiasis (chagas disease)

caused by T. cruzi

trans: triatomid insect bites (Triatoma bug, kissing bug)

parasites reproduce in the blood while the pt may remain asymptomatic.

chronic, irreversible disease may appear in 10-30 years 

• Romana’s sign, fever heptasplenomegaly 

Toxoplasma Gondii (toxoplasmosis)

• parasite disease cause by protozoan

• can infect most warm blooded animals, cats are primary host & major reservoir

• Infection spreads through eating infected meat, ingestion of feces  

• mild flu like illness or none 

toxoplasmosis

• no serious illness occurs in most people

• parasites cross across the placenta and infect fetal tissue in pregnant women can can cause: neurologic damage, hydrocephalus, spontaneous abortion

• TORCH antibody for panel pediatrics - diagnosing prenatal infection

• HSV1 and II

• Can cause harm for AIDS pt.: inflammation, swelling, cerebral lesions, seizures death

Primary Amebic Meningoencephalitis (PAM) - Naegleria Fowleri

free living (brain eating) amoeba

• warm lakes, ponds, rock pits, mud puddles

• can not live in salt water, swimming pools, or properly treated municipal water

• leads to destruction of brain tissue, meninges

• death within 1-12 days