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Pneumocystis jirovecii and Toxoplasma ygondii:

A Tale of Two Parasites orOpportunistic Infections In Immuno-deficient Hosts

Charles Knirsch, MD, MPH

Protozoan Parasites1. Toxoplasma gondii

2 Th M l i2. The MalariasPlasmodium falciparumPlasmodium vivaxPlasmodium ovalePlasmodium malariae

3 Diarrheal disease-causing protozoa:3. Diarrheal disease-causing protozoa:Giardia lambliaEntameba histolyticaCryptosporidium parvumCyclospora cayetanensis

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Toxoplasma gondii

Protozoa:

and

Pneumocystis jirovecii*formerly P. carinii

*actually an unusual fungus

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Western & Central Europe

Eastern Europe & Central Asia

Adults and children estimated to be living with HIV, 2007

Central Europe730 000730 000

[580 000 [580 000 –– 1.0 million]1.0 million]

Middle East & North Africa

380 000380 000[280 000 [280 000 –– 510 000]510 000]Sub-Saharan Africa

22.0 million22.0 million[20.5 [20.5 –– 23.6 million]23.6 million]

& Central Asia1.5 million 1.5 million

[1.1 [1.1 –– 1.9 million]1.9 million]

South & South-East Asia

4.2 million4.2 million[3.5 [3.5 –– 5.3 million]5.3 million]Oceania

74 00074 000[66 000 [66 000 –– 93 000]93 000]

North America1.2 million

[760 000 – 2.0 million]

Latin America1.7 million1.7 million

[1.5 [1.5 –– 2.1 million]2.1 million]

East Asia740 000740 000

[480 000 [480 000 –– 1.1 million]1.1 million]Caribbean230 000

[210 000 – 270 000]

Total: 33 million (30 – 36 million)

[[ ]]

And the Band Played On• Politics, people and the AIDS epidemic, p p p• CDC April 1981: “This guy should go back

to medical school if he can’t find some simple neoplasm”

• June 1981 MMWR: Pneumocystis pneumonia in young men

• GRID

4

Opportunistic Infections Associated with Progressive

Immunodeficiency500500

4+ T

-Lym

phoc

ytes

r C

ubic

Mill

imet

er

500500450450400400350350300300250250200200150150

TBTBThrush & vaginal candidiasisThrush & vaginal candidiasis

PCP, Chronic or recurrent herpes infections

PCP, Chronic or recurrent herpes infections

Systemic fungal infections CMVSystemic fungal infections CMV

CD

4pe

r

1001005050

0066 1212 1515

Time After HIV Infection (Years)

infections, CMV, Toxoplasmosisinfections, CMV, Toxoplasmosis

MACMAC

1010

Pneumocystis jirovecii (PCP)

• Commensal organism and opportunistic• Commensal organism and opportunistic pathogen

• Morphologically resembles protozoan• Difficult to grow in vitro• Life cycle???• Life cycle???

– Cyst stage : 5 um in diameter with 4-8 sporozoites

– Trophozoite : 2-5 um in diameter – attach to cell surfaces

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6

PABA (Para-aminobenzoic Acid)

Pteridine +

Sulfonamides /Dapsone

Dihydropteroate Synthetase

Folic Acid Inhibitors are Drugs of Choice for PCP

Folic acid

Dihydrofolic acid

Pyrimethamine, Proguanil

Dihydrofolate reductase

Tetrahydrofolic acid

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Is P. carinii a Fungus or Protozoon?

ProtozoonM h l• Morphology

• Inability to culture in vitro• Response to anti-protozoal drugsFungus• Ribosomal rRNA sequence homology• ELF3

AnimalsAnimals

PlantsPlants

ProtozoaProtozoaFungiFungiSlime moldsSlime molds

Algae (red brownAlgae (red brown

Higher protistsHigher protistsEarly protozoaEarly protozoa

Algae (red, brown, green, others)Algae (red, brown, green, others)

Cyanophytes (blue-green algae)Cyanophytes (blue-green algae)

BacteriaBacteria

Lower protistsLower protists

??

??

??

Ancestral procaryotic group

Ancestral procaryotic group

Precellular forms Precellular forms

VirusesViruses

????

??

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Protozoa:

Toxoplasma gondii

Toxoplasma gondii

The Apicomplexa

Toxoplasma gondiiThe Plasmodia (malaria)Cryptosporidium hominis

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Toxoplasma gondii infects all mammalsand all tissues in each of them.

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Felines are the definitive hosts for Felines are the definitive hosts for Toxoplasma gondiiToxoplasma gondii

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Oocysts of Toxoplasma gondii

Sporulated

Unsporulated

Rack of lamb is usually served rare

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Macrophage Infected With Toxoplasma gondii*

* The hunter becomes the hunted

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Toxoplasma gondii in culture

Trophozoites (T) prevent fusionof lysosomal menebranes to thparasitophorous vacuole, thereescaping digestion

Toxoplasma gondii in culture

Heat-killed organisms cannotprevent fusion of lysosomal membranes with the parasitophorous vacuole

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C it l

Clinical Disease:

Congenital

Adult-acquired

AIDS relatedAIDS-related

Congenital Toxoplasmosis

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Calcified Lesions Due To Congenital Toxoplasmosis

Congenital Toxoplasmosis

Photo courtsey: Gary Baumbach, M.D., Department of Pathology, University of Iowa College of Medicine

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Congenital Toxoplasmosis:

Still Birth

Chorioretinitis

Mental Retardation

Congenital Toxoplasmosis Following Maternal Infection During First and Second Trimester*

Not Infected 73%Subclinical Infection 13%Mild Infection 7%Severe Infection 6%Severe Infection 6%

* From Desmonts and Couvier, NEJM 290: 1110, 1974

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Toxoplasma Ocular Disease

• Usually from congenital infection• Usually from congenital infection manifesting in adults– Episodic flares may destroy retinal tissue– Specific treatment necessary

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Adult-Acquired Toxoplasmosis

Infection by Blood or Organ Transplant

• Parasitemia (WBC’s) for up to 1 year• Parasitemia (WBC s) for up to 1 year post infection

• Heart, bone marrow, liver, kidney donors– Dangerous when recipient toxo (-)g p ( )

• Myocarditis, diffuse lymphadenopathy

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Adult-Acquired Toxoplasmosis

Signs and symptoms:Lymphadenopathy

Fever

Headache

Chronic Malaise

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Differential Diagnosisof LymphadenopathyDifferential Diagnosisof Lymphadenopathy

ToxoplasmosisToxoplasmosis

++++++

Inf. MonoInf. Mono

++

LymphomaLymphoma

++++++L h d th With tLymphadenopathy Without +++

+

+++

+

0

0

+++

+

+++

+

0

0

+

+++

+

++++

+

++++

+

+++

+

++++

+

++++

+++

+

+++

+

+++

0

+++

+

+++

+

+++

0

Lymphadenopathy WithoutOther Symptoms

Pharyngitis

Monocytosis, Eosinophilia

Atypical Lymphocytes

Anemia

Positive Heterophil

Lymphadenopathy WithoutOther Symptoms

Pharyngitis

Monocytosis, Eosinophilia

Atypical Lymphocytes

Anemia

Positive Heterophil 0

0

+

ReticulumCells

0

+

ReticulumCells

++++

+

Germinal Cells

++++

+

Germinal Cells

0

++

+++

Bizarre Cells

++

+++

Bizarre Cells

Positive Heterophil

Altered Liver Function

Hilar Lymphadenopathy

Lymph Node Pathology

p

Altered Liver Function

Hilar Lymphadenopathy

Lymph Node Pathology

Pseudocyst of Toxoplasma gondii in Liver

PseudocystPseudocyst

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AIDS-related Disease

Pseudocysts of Toxoplasma gondii in a microglial nodule with a variety of inflammatory cell types

in an HIV/AIDS patient

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AIDS-related Disease:1. CD4 < 200 and reactivation of latent infection

2 Encephalitis2. Encephalitis1. Diffuse inflammation and swelling2. Localized ring enhancing lesions on CT scan3. Herniation4. Death if untreated

Toxoplasma abscess in the brain would appearas a ring-enhancing lesion with CT scan.

CT Scan

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Diagnosis

Serological correlatesin acute and chronic infection

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Indirect Fluorescent Antibody (IFA)Test

PABA (Para-aminobenzoic Acid)

Pteridine +

Sulfonamides /Dapsone

Dihydropteroate Synthetase

Folic Acid Inhibitors are Drugs of Choice

Folic acid

Dihydrofolic acid

Pyrimethamine, Proguanil

Dihydrofolate reductase

Tetrahydrofolic acid

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Prevention:

1. Prevent pregnant women from handling cat litter

2 Avoid eating raw or under-cooked meats2. Avoid eating raw or under-cooked meats

Automated litter collection boxTrained cat

Host status

• Pneumocystis • Toxoplasma• Pneumocystis carinii– No Life cycle!– Lung disease in

AIDS– Malnourished

• Toxoplasma gondii– Cat definitive host– Disease: Host status– CNS Disease in

AIDSMalnourished children

– Organ Transplants

AIDS– Congenital Infections– Organ Transplants

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Disease Number of Cases Population at-risk

Ascariasis 807 million 4.2 billion

The Most Common Neglected Infections of Poor People

Trichuriasis 604 milion 3.2 billion

Hookworm 576 million 3.2 billion

Amebiasis 500 million ND

Schistosomiasis 200 million 0.6 billion

Lymphatic Filariasis 120 million 1.0 billionTrachoma 84 million 0 5 billionTrachoma 84 million 0.5 billion

Onchocerciasis 18 million 0.1 billionChagas Disease 16 million 0.1 billionLeishmaniasis 12 million 0.4 billionLeprosy 0.4 million ND

Dracunculiasis 0.01 million ND

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Global Network for Neglected Tropical Diseaseshttp://www.GNNTDC.org

• Schistosomiasis Control Initiative I t ti l T h I iti ti• International Trachoma Initiative

• Helen Keller International• Liverpool School - GAELF• Human Hookworm Vaccine Initiative• Earth Institute at Columbia Univ.• Task Force for Child Survival

– Mectizan Donation Program– Albendazole Donation Program– Mebendazole Donation Program