1. Blood & Tissue Protozoa
Lange Chapter 52
Faculty: AGUAZIM SAMUEL, M.D.

2. The medically important organisms:
The sporozoans: Plasmodium and Toxoplasma
The flagellates: Trypanosoma and Leishmania

3. CASE
40 year old male on a business trip to WEST AFRICA presented with sudden fever, joints pains and headache which were most severe every 3rd day. In between, he would fell weak, but the fever would lyse.
He had vaccine for yellow fever and HAVRIX prior to leaving the US.
He was staying in a urban hotel, and had limited trips except for the office.

4. CASE
Thick blood smear showed:

5. CASE
Impression: Malaria, probably non-Chloroquine resistant; secondary to Plasmodium species

6. It was discovered more than 100 years ago
A French army doctor in Algeria observed parasites inside red blood cells of malaria patients and proposed for the first time that a protozoan caused disease
-Malaria can present with a non-specific prodrome lasting up to several days. Symptoms include malaise, anorexia, headache, myalgia and low grade fever. However, malaria can also start more suddenly, with acute onset of severe illness.
-After several more days, the classic cyclic "paroxysms" may develop. These include 3 stages – cold, hot, & sweating. It may take 3-7 days for the cycles to appear, if they appear at all. Until then the fevers may be erratic.
-The cold stage lasts 15 minutes to several hours. Symptoms include feeling cold, shivering, and teeth chattering. Temp rises rapidly, skin is pale and cold, may see cyanosis of the lips and nail beds.
-The hot stage lasts 2 to 6 hours. Fever is up to 106F with falciparum and up to 104F with others. Symptoms include severe headache, malaise, myalgia, anorexia, nausea and vomiting, diarrhea, dry cough, and shortness of breath; may have delirium.
-The defervescence or sweating stage lasts 2 to 4 hours. The fever falls rapidly; there is profuse sweating. Afterward, the patient may be exhausted and sleep for hours, but is much improved.
-After an interval free of fever the cycle of chills, fever, and sweating is repeated either daily, every other day, or every 3rd day.
-With falciparum, fevers tend to be persistent with intermittent spikes. Falciparum malaria is typically not as cyclic as the other three. But remember that these classic paroxysms often are not present, and that malaria can have ANY pattern.
Ref: 1.
Charles Louis Alphonse Laveran

7. 1907 Nobel Prize for Physiology or Medicine!
French army doctor in Algeria observed parasites inside red blood cells of malaria patients and proposed for the first time that a protozoan caused disease
-Malaria can present with a non-specific prodrome lasting up to several days. Symptoms include malaise, anorexia, headache, myalgia and low grade fever. However, malaria can also start more suddenly, with acute onset of severe illness.
-After several more days, the classic cyclic "paroxysms" may develop. These include 3 stages – cold, hot, & sweating. It may take 3-7 days for the cycles to appear, if they appear at all. Until then the fevers may be erratic.
-The cold stage lasts 15 minutes to several hours. Symptoms include feeling cold, shivering, and teeth chattering. Temp rises rapidly, skin is pale and cold, may see cyanosis of the lips and nail beds.
-The hot stage lasts 2 to 6 hours. Fever is up to 106F with falciparum and up to 104F with others. Symptoms include severe headache, malaise, myalgia, anorexia, nausea and vomiting, diarrhea, dry cough, and shortness of breath; may have delirium.
-The defervescence or sweating stage lasts 2 to 4 hours. The fever falls rapidly; there is profuse sweating. Afterward, the patient may be exhausted and sleep for hours, but is much improved.
-After an interval free of fever the cycle of chills, fever, and sweating is repeated either daily, every other day, or every 3rd day.
-With falciparum, fevers tend to be persistent with intermittent spikes. Falciparum malaria is typically not as cyclic as the other three. But remember that these classic paroxysms often are not present, and that malaria can have ANY pattern.
Ref: 1.
Charles Louis Alphonse Laveran

8. PLASMODIUM Disease: Malaria
Malaria is caused by four plasmodia: vivax, ovale, malariae, and falciparum.
Vivax and falciparum are more common causes of malaria than are ovale and malariae.

9. Malaria
300–500 million infections worldwide and approximately 1 million deaths annually.
10 million new cases
more than 2 million die of it each year, making it the most common lethal infectious disease.

10. Important Properties of Malaria
The vector and definitive host for plasmodia is the female Anopheles mosquito (only the female takes a blood meal).
There are two phases in the life cycle:
Sexual cycle, which occurs primarily in mosquitoes.
Asexual cycle, which occurs in humans the intermediate hosts.

11. Sexual Asexual 1. Sporozoite 2. Parenchymal cells of the liver.
13. Fertilization
14. Invasion of gut mucosa
15. Oocyte
16. Sporozoite
17. Released into gut
18. Salavary glands
1. Sporozoite
2. Parenchymal cells of the liver.
4. Mature in two weeks into schizonts.
5. Rupture to produce 10-40,000 merozoites.
6. Circulate for a few minutes before entering the red blood cell.
7. Merozoites mature into the ring form in the RBC.
8. From ring form to Trophozoite.
9. From Trophozoite to Schizont.
10. Completion of life cycle to release merozoites into the blood stream.
11. Some merozoites initiate the sexual stage to form male and female gametocytes.
12. Gametocytes taken up by the Anophles mosquito; eight male microgametes and female macrogametes are produced in the gut.
Sexual
Asexual
Some ring form merozoites, go on to initiate the sexual stage, maturing within the red blood cells to form male and female gametocytes
12) Which can be taken up by the Anopheles mosquito on feeding. On entering the gut of the insect, produce, eight spermlike male microgametes and female macrogamete.
13) The male microgametes fertilize the female macrogamete to form the zygote.  
(14) This then invades the gut mucosa.
(15) Where it develops into an oocyst.
(16) This develops to produce thousands of sporozoites
17) Which are released into the gut.
(18) Finally migrating to the salivary glands of the insect.
whence the cycle begins again

13. Mosquito feeds on blood of infected host & ingests gametocytes

14. Gametes unite in mosquito stomach to form oocysts in wall of stomach

15. Oocysts

17. Sporozoites produced in oocysts by sporogony move to salivary glands of mosquito & are injected into next host

18. Sporozoites invade liver cells and undergo schizogony to produce merozoites

19. Merozoites invade circulating RBCs

20. Each merozoite produces as many as 36 new merozoites through schizogony in RBCs

21. Merozoites rupture RBCs to invade other RBCs
Simultaneous lysing of RBCs causes the sudden chills & fever typical of malaria

22. Gametocytes are produced in blood & ingested by mosquito to complete the cycle

23. Man
Mosquito
Sporozoites from mosquito bite
Ingest gametocytes
Sporozoites to liver
Fertilization in stomach
Oocyst forms
Schizogony to make merozoites
Merozoites enter RBCs
Sporozoites by sporogony
Schizogony to make merozoites
Sporozoites invade salivary gland
Merozoites become gametocytes
Bites man

25. Plasmodium falciparum merozoites ring form.
                                          
Plasmodium falciparum merozoites ring form.

26. Pathogenesis of Malaria:
Most of the pathologic findings of malaria result from the destruction of red blood cells.
Red cells are destroyed both by the release of the merozoites and by the action of the spleen.
Malaria caused by P falciparum is more severe than that caused by other plasmodia.
It is characterized by infection of far more red cells than the other malarial species.

27. Malaria Clinical Findings
Abrupt onset of fever, chills and Headache
Myalgias, about 2 weeks after the mosquito bite.
Fever may be continuous early in the disease
Untreated malaria caused by P. falciparum is potentially life-threatening as a result of extensive brain and kidney damage.
Malaria caused by the other three plasmodia is usually self-limited, with a low mortality rate.
life-threatening hemorrhage and necrosis, particularly in the brain (cerebral malaria).
Extensive hemolysis and kidney damage occur, with resulting hemoglobinuria.
The dark color of the patient’s urine has given rise to the term “blackwater fever.”

28. Malaria Clinical Differences between species:
P. falciparum causes a high level of parasitemia, because it can infect red cells of all ages.
P vivax infects only reticulocytes.
P malariae infects only mature red cells; they produce much lower levels of parasites in the blood.

29. SPECIES
DISEASE
IMP:FEATURES
BLOOD
SMEARS
LIVER STAGES
TRT
P.VIVAX
BENIGN TERTIAN
48HRS FEVER SPIKES
Enlarge host cells, schuffner’s dots ameboid trophozoites
Persistent hypnozoites relapse
Chloroquine then primaquine( needed to eliminate the exoerythrocytic form)
p. ovale
“ “ “”
Oval, jagged, infected RBC
P .malariae
Quartan or malarial
72hrs fever spikes, recrudescence
Bars and band forms, rosette schizonts
No persistent, Recrudescence
chloroquine
P .falciparum
Malignant tertian
Irregular fever spikes, cerebral malaria
Multiple ringforms, crescent shape gametes
Chloroquine resistance a problem

30. Bars and band forms,
schuffner’s dots
Multiple ringforms,
Oval, jagged, infected RBC

31. Sickle Cell Anemia and Malaria
Individuals with sickle cell trait are protected against malaria
Their red cells have too little ATPase activity and cannot produce sufficient energy to support the growth of the parasite.

32. Malaria and the Duffy antigen
The receptor for P vivax is the Duffy blood
group antigen.
People who are homozygous recessive for the genes that encode this protein are resistant to infection by P. vivax.
More than 90% of black West Africans and many of their American descendants do not produce the Duffy antigen.
Homozygous: having identical genes at one or more loci

33. intravenous drug abuse also occur.
Malaria is transmitted primarily by mosquito bites, but transmission can occur:
across the placenta
in blood transfusions
intravenous drug abuse also occur.

34. Laboratory Diagnosis of Malaria:
Diagnosis rests on microscopic examination of blood, using both thick and thin Giemsa-stained smears.
- thick smear: used to screen for the presence of organisms
- thin smear is used for species identification.

35. It is important to identify the species, because the treatment of different species can differ.
Ring shaped trophozoites can be seen within infected red blood cells.
The gametocytes of P. falciparum are crescent shaped (banana-shaped)
The gametocytes of the other plasmodia are spherical.

36. P falciparum female gametocyte banana-shaped

37. Treatment of Malaria:
Chloroquine:acute malaria: (kills the merozoites) reducing the parasitemia. Check CDC for Chloroquine resistant areas!!!
Dose, 500 mg. orally per week for one week prior to travel, during travel and 4 week afterwards.
Chloroquine prophylaxis only effective for travelers to malaria-risk areas in:
- Mexico -Central America
- Haiti -Middle East
- Dominican Republic -Eastern Europe

40. Other Malaria Treatments
For chloroquine resistant strains of P falciparum: mefloquine, doxycycline or a combination of quinine and Fansidar is used. Neurologic side effects such as psychosis for Mefloquine.
Primaquine or Pyrimethamine: is used to treat the hypnozoites of P vivax and P ovale in the liver. Primaquine must be used to prevent relapses.
Malarone: new drug: combination of atovaquone and proguanil. First dose 1-3 days before travel, during travel and 7 days after travel. Can’t use in pregnant women, breast-feeding women and infants< 24 lbs.

41. Prevention of Malaria: Chemoprophylaxis
Travelers to areas where the plasmodia are found should take chloroquine starting 1-2 weeks before arrival and continuing for 4-6 weeks after departure.
Travelers to areas where chloroquine resistant P falciparum is endemic consists of mefloquine. This should be followed by a 2-week course of primaquine if exposure was high.
use of mosquito netting, window screens, protective clothing, and insect repellents.
The mosquitoes feed from dusk to dawn, so protection is particularly important during the night.

42. Although….
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43. Babesia Babesiosis: fever and hemolytic anemia(malaria-like)
Predominantly in the northeastern U.S.
Co-infection with borrelia
Blood smear, no RBC pigment
Appears as a “Maltese cross”(tetrad in RBCs)
MOT: TICK BITE(ixodes tick)
hemolytic anemia, jaundice, fever and hepatomegaly, usually 1-2 weeks after infection
DOC:atovaquone and azithromycin (mild-to-moderate cases) or clindamycin and quinine (severe or resistant cases).

44. Acanthamoeba castellanii (FREE-LIVING AMEBA)
"the brain-eating amoeba“
Rapidly fatal meningoencephalitis
( granulomatous amebic encephalitis)
Thought to be acquired via respiratory route and via breaks in the skin
Their life cycle involves trophozoite and cyst stages. Cysts are quite resistant and are not killed by chlorination
Free living amebae in contaminated and contact lens solution(airborne-cyst)
DX: Amoebas in spinal fluid
Pentamidine, ketoconazole, or flucytosine may be effective in Acanthamoeba infections
ACANTHAMOEBA ALSO CAUSES KERATITIS .

45. Naegleria fowleri (FREE-LIVING AMEBA)
"the brain-eating amoeba“
Rapidly fatal meningoencephalitis
( primary amebic meningoencephalis), severe frontal headache, nausea, high fever. Altered sense of smell ( often fatal)
Swimming in freshwater lakes
Their life cycle involves trophozoite and cyst stages. Cysts are quite resistant and are not killed by chlorination
Enters via the cribriform plate
DX: Amoebas in spinal fluid
AMP B MAY BE EFFECTIVE FOR NAEGLERIA

46. Tissue Protozoa

47. Toxoplasma gondii
Disease: Toxoplasmosis

48. WHAT IS TOXOPLASMOSIS?
Toxoplasmosis is an infection caused by a parasite most often found in cats and farm animals. Humans can catch this disease from:
coming into contact with infected cat feces
eating raw or undercooked meat that’s infected
eating contaminated vegetables or fruits
being born with it
Note: Once a person is infected, the infection remains in the body for life, usually in an inactive form. It can reactivate when that person’s immune system is weak.

49. Epidemiology
More than 60 million people in the United States probably carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness. However, expectant mothers should be cautious because an infection can cause problems in pregnancy.
Image pictured is of brain tissue with abnormal growth due to toxoplasmosis

50. About 98% of cases of Toxoplasmosis are acquired through Congenital Toxoplasmosis.
One study showed that 76% of infants infected with congenital toxoplasmosis had ocular lesions, 51% had neurological involvement, and 26% had either hydrocephalus (increased intracranial pressure) or microcephaly (small brain). It is evident that vision problems are very common with Congenital Toxoplasmosis.
Once the mother develops immunity to the organism, all future pregnancies are protected from transmission of the organism.

51. Toxoplasma Characteristics:
Tissue protozoan.
Life cycle in human:
Cysts in cat feces or meat
Ingested by humans
Differentiate in the gut and invade
Infect macrophages
Form trophozoites (tachyzoites) that multiply, kill cells, and infect other cells
Cysts containing bradyzoites form later in the host cell, brain, muscle, and other tissues!!!!!!

52. Toxoplasmosis (tachyzoite form) of myocardium
Toxoplasmosis (tachyzoite form) of myocardium. Note the intracellular cyst formation.

53. Infective form: oocysts Pathogenic form: tachyzoite

54. Toxoplasma Life cycle in cat:
1. Cat ingests cysts in raw meat
2. Bradyzoites released from the cyst in the small intestine.
3. Multiply, and form gametocytes.
4. These fuse to form oocysts in cat gut, which are excreted in cat feces.
Bradyzoites: cysts in which the organism multiplies slowly.

55. Toxoplasma
Human infection: usually occurs from eating undercooked meat lamb or pork, from animals that grazed in soil contaminated with infected cat feces.
Transmission: Transmitted by ingestion of cysts and transplacentally from mother to fetus. Cat is definitive host; humans and other mammals are intermediate hosts. Occurs worldwide.
Definitive host: The host in which the organism reproduces sexually.

56. Toxoplasma
Pathogenesis: Trophozoites infect many organs, especially brain, eyes, and liver. Cysts persist in tissue.
Laboratory Diagnosis: Serologic tests for IgM and IgG antibodies are usually used.
Treatment: Sulfonamide and pyrimethamine for congenital or disseminated disease.
Leucovorin (folinic acid rescue) to avoid marrow suppression
Prevention: Meat should be cooked. Pregnant women should not handle cats, cat litter boxes, or raw meat.

57. Toxoplasma
In immunocompetent individuals, the host response contains infections and patients present asymptomatically or with a mononucleosis-like illness such as sore throat, fever, and swollen lymph nodes.

58. Toxoplasma
In immunocompromised individuals, cysts rupture and release tachyzoites that leads to toxoplasmosis. Patients present with:
Chorioretinitis
Encephalitis
Pneumonitis (rarely)

59. Ring Enhancing lesion Toxoplasmosis

60. CONGENITAL TOXOPLASMOSIS
classic clinical triad
retinochoroiditis
cerebral calcifications
convulsion
TORCH
T – Toxoplasmosis
O – Others (VSZ and Parvovirus B19
R – Rubella
C – CMV
HE – Herpes, HIV
S – Syphilis

61. CONGENITAL TOXOPLASMOSIS
If a pregnant woman without previous exposure becomes infected, T. gondii protozoa may cross the placenta, causing congenital toxoplasmosis.

62. Children infected in utero with Toxoplasma, rubella, cytomegalovirus, or herpes simplex virus show remarkably similar symptoms.

63. 3. Children born with Toxoplasmosis, which accounts for about 98% of cases, may show symptoms including:
Fever
Swollen glands
Jaundice
An unusually large or small head
Rash
Bruises or bleeding under the skin
Anemia
Enlarged liver or spleen
Seizures
Limp muscle tone
Mental retardation
Hearing loss
Vision problems (toxoplasmosis of the eye)

64. TOXOPLASMOSIS

65. Ocular toxoplasmosis: Macular scarring

66. DAMAGE TO THE EYE
The parasite usually invades the retina and the choroid tissue. Depending upon the area and severity of the infection, visual acuity can be unaffected to severely affected. The retina is inflamed by the infection and sometimes when the inflammation settles, scars are left on the retina. Symptoms include floaters and blurred vision. If the scarring is on the central macula, detailed vision will be affected. Approximately 35% of all retinachoroiditis cases can be attributed to toxoplasmosis.
Active Toxoplasmosis Inactive Toxoplasmosis Scar
                              

67. Effects of Ocular Toxoplasmosis
Common Effects:
Inflammation of retina
Blurred vision
Floaters
Nystagmus
Amblyopia
Squint
Occasional Effects:
Cataracts
The eye can be small
Optic atrophy
Cerebral visual impairment

68. Blueberry muffin rash (congenital toxoplasmosis, rubella, CMV)

69. Classic Triad of Congenital toxoplasmosis
Chorioretinitis ( Cotton-like white/yellow scars on the retina)
Hydrocephalus
Intracranial calcification( multiple ring- enhancing lesions in the cortex and basal ganglia on head CT)

70. Thank You!!!!
In the Race of Life Overtaking is Permitted. Remember Life is a Privilege not a right. DRS