Phylum Apicomplexa Final

Front 1

Cryptosporidium parvum

Back 1

•Transmissionby oocysts incontaminated water or food; too small to be filtered out by normal watertreatment facilities.

•Invadesand lyses intestinal epithelium cells.•Symptoms–severe watery diarrhea, abdominal cramping, and weight loss.

–Normally1-10 day infection

–Severe infection in AIDS patients

•6-25bowel movements per day•Dehydration,electrolyte imbalance, and death.

Front 2

Cryptosporidium parvum 2

Back 2

•Diagnosis: Oocysts in fecal float.•Treatment: None. Testing nitazoxanide. Lack mitochondria so drugs that killanaerobic bacteria may be effective.•Prevention: Filtered or bottled water.–Municipalwater systems can’t filter out the oocysts and chlorine does not kill oocysts.•Boilingand freezing below -10oF does kill it.–Outbreakshave occurred in many areas•Particularlyin the spring•This is another organism that has onlybecome known due to AIDS research.

Front 3

CryptosporidiumLife Cycle

Back 3

•Ingestion of oocyst,sporozoites emerge•Sporozoites invade intestinal cells

•Merogony for multiple generations in intestine•Gametogony in intestine

•Oocysts released in feces

Front 4

Cryptosporidium Life Cycle 2

Back 4

Front 5

Toxoplasma gondii

Back 5

•“Toxoplasma”derives from the Greek (toxon: bow) in reference to the organism’screscent shape

•Broadhost and tissue specificity; infects almost all nucleated cells.

•Mostpeople show no or benign symptoms (headache, sore throat, fever)

Front 6

Toxoplasma gondii 2

Back 6

•DefinitiveHost: Cats of many species•IntermediateHosts:domestic and wild animals – Anything a cat would eat

–Humans– accidental host and dead end•GeographicDistribution: Cosmopolitan–50%prevalence in U.S.–13%worldwide

•Modeof Transmission: Cat ingests infected host or oocyst

–Humansaccidentally ingest oocysts in feces

Front 7

Life cycle of Toxoplasma gondii

Back 7

•Intestinalphase (cats):

•Cat ingests oocysts or tissue cysts, which release sporozoites

•Merogony for multiple generations•Gametogony produces oocysts which are excreted in the feces andremain infective for months. •

•Oocysts must sporulate to become infective (about 48hours after defecation)

Front 8

Life cycle of Toxoplasma gondii2

Back 8

•Tissuephases (intermediate host):

• IH ingests oocysts or tissue cysts, which release sporozoites

• Sporozoitespenetrate the intestine and invade macrophages and other types of cells.

• Parasites multiply by merogony

Merogonyin IH:

• “Tachyzoites” arereleased which will invade new host cells

• As the host develops immunity,replication rate slows down and parasites form “tissue cysts” containing “bradyzoites”.

Front 9

Toxoplasma gondii parasiticforms

Back 9

•TACHYZOITES:rapidly growing meronts observed in the early stage of infection

• BRADYZOITES:Slow-growing merontsinside the tissue cysts

• TISSUE CYSTS:Found in the tissues and contain bradyzoites. Infective form.

OOCYSTS:Zygote form. Highly resistant. Infective form

Front 10

Bradyzoite cysts

Back 10

•Bradyzoites markthe beginning of the chronic phase of infection

•Tissuecysts show very little evidence of inflammation or immune cell infiltrates.•Bradyzoites (not tachyzoites) are resistant to low pH and digestiveenzymes during stomach passage

•Protective cyst wall is eventuallydissolved and bradyzoites infect tissue to transform into tachyzoites

•Tachyzoites:pathogenesis

Bradyzoites:transmission

Front 11

Toxoplasma crieteria

Back 11

•Threesituations can lead to severe disease:

1) ocular toxoplasmosis

2) lossof a functional immune system

3) congenital toxoplasmosis

Front 12

Effects of Toxoplasmosison Intermediate Hosts

Back 12

•Abortionand stillbirth in many mammals•Neurologicalsymptoms– head shaking, lack of co-ordination, seizures and tremors

•Rats–behaviors that increase transmission

–decreased ability to learn in mazes

–increased activity

–increased preference for exposed areas–Attracted to cat urineR

Front 13

Toxoplasmosis Prevention

Back 13

•Avoidraw or undercooked meat. (Cooking kills Toxoplasma)

•Wash raw fruits and vegetables wellbefore eating.

•Remove cat feces from the litter box every day, to eliminate any parasitesbefore oocysts sporulate

•Keep cats from getting infected:

• Prevent hunting (keep indoors)

• Feed cats only commercial food or well-cooked meat.

• Do not adopt cats who have lived outdoors orwho have been fed raw meat.

• Do not handle stray cats.•

•Wash hands well with soap and warm water after:

• Gardening

• Yard Work•

• There is no treatment available to prevent Toxoplasma in cats, or to prevent an infected cat from shedding the parasite in its stool.{i

Front 14

TreatingToxoplasmosis]

Back 14

•Combination of:

-Pyrimethamine– antimalarial drug

-Sulfonamides– class of antibiotics that workssynergistically with pyrimethamine

- side effects can be severe inAIDS patientst

Front 15

T. gondii andHuman Behavior"

Back 15

•Acuteinfections can cause schizophrenic symptoms

Reactivationof cysts in AIDS patients cause delusions, auditory hallucinations and “thoughtdisorders”

•Sexdifferences:

–Infectedmen more likely to score lower on relationship warmth, self-control andtidiness (increased “masculine” traits)

–Femalesopposite response.

–Bothmore guilt-prone