*Varies in each area, in India and Africa, the dog apparently is not involved in L. donovani transmission. RES = Reticuloendothelial system. 146 Concise Book of Medical Laboratory Technology: Methods and Interpretations TABLE 8.4: Blood flagellate diseases of man Disease and etiology Clinical features Laboratory diagnosis

 

concentration, culture

10–40% of women examined. It is mainly transmitted

by coitus but may also be transferred by recently

contaminated toilet articles. The male is the chief agent of

spread, although he seldom suffers symptoms. Treatment

of the female, however, should always include treatment

of her sexual partner.

The Basis of Serum Biochemical Tests for Leishmaniasis

These tests assess alterations in serum proteins particularly

serum gamma globulin. The positive results are obtained

after 2 to 3 months or more.

Napier’s aldehyde test: When serum of the patient is treated

with formaldehyde, it causes flocculation and opacity. To

1 mL of patient’s serum, add 2 drops of formaldehyde—if

flocculation and opacity occur within 10 minutes, the test

is strongly positive. If this change occurs in about 2 hours

time, it is labeled as weakly or doubtful positive.

Chopra’s antimony test: Dilute patient’s serum 10 times

with normal saline. To 1 mL of diluted serum, add 2 drops

of 4% urea stibamine solution. Immediate appearance of

flocculum and turbidity indicates a positive test.

For exact determination of individual classes of gamma

globulins, immunoturbidometric or nephelometric

techniques may be used. However, for screening purposes

and normal routine clinical testing, the given above tests

are quite satisfactory.

ELISA techniques are ideal.

126 Concise Book of Medical Laboratory Technology: Methods and Interpretations Entamoeba histolytica

Morphology

Contd...

Medical Parasitology 127

Contd...

128 Concise Book of Medical Laboratory Technology: Methods and Interpretations Entamoeba histolytica (causing amebiosis) life cycle

Medical Parasitology 129

Pathogenesis

Contd...

130 Concise Book of Medical Laboratory Technology: Methods and Interpretations Contd...

Medical Parasitology 131

The Intestinal Flagellates

132 Concise Book of Medical Laboratory Technology: Methods and Interpretations Intestinal Cilliate

Balantidium coli (Causing Balantidiasis)

Medical Parasitology 133

The Nonpathogenic Intestinal Amebae

134 Concise Book of Medical Laboratory Technology: Methods and Interpretations MALARIAL PARASITES OF MAN (TABLE 8.2)

TABLE 8.2: Morphology of different erythrocytic forms of plasmodia of man

P. vivax P. falciparum P. malariae P. ovale

Trophozoite

Size Relatively large, 2.5 µ Small; < 1.5 µ Relatively large, 2.5 µ Relatively large, 2.5 µ

Shape Round or oval,

delicate ring

Round or oval, very delicate

ring

Round or oval, compact ring Round or oval, dense

ring

Chromatin Prominent dot in thin part

of cytoplasm or in vacuole;

at times two dots

Fine dot; frequently two or bar

shaped

A prominent mass often inside the vacuole of the ring.

‘Bird’ eye form is common

A dense well-defined

mass at the thin segment

of the cytoplasm

Accole form At times thickened Frequent None None

Cytoplasm Opposite to chromatin No thickening opposite to

chromatin

Thicekned all through,

more opposite to chromatin

Thickened opposite to

chromatin

Pigment Nil Nil May be present Nil

Number in an RBC One May be more One One

Growing form rarely seen in peripheral blood

Size Large Small Small Small

Shape Irregular; ameboid with

fine streaming cytoplasmic

pseudopodia

Compact Compact; cytoplasm more

collected together; egg

form, equatorial band form,

Ribbon, comet form

Compact; may be slightly

ameboid

Vacuole Prominent Inconspicuous Disappears early Inconspicuous

Chromatin Dots or threads Dots or threads; chromatin is

relatively more

compared to cytoplasm

Dots or threads Large irregular clumps

Pigment color Yellowish brown Black or pepper-like Dark brown Dark yellowish brown

Microgametocyte (male)

Size Large (10 to 12 µ); fills

enlarged RBC

Large (8 to 10 µ × 2 to 3 µ);

larger than RBC

Smaller than size of a

normal RBC

About the size of normal

RBC

Shape Round or oval, compact Kidney or bean shaped; ends

bluntly rounded

Round; compact Round; compact

Cytoplasm Light blue Pinkish blue Reddish blue (stains badly) Pale blue

Chromatin Fibril in skin; large, diffuse;

stains poorly; lies across

equator, surrounding area

unstained

Fine granules; scattered through

1/3 of the body of the parasite

lie amongst pigment granules,

stains lightly in the central part

Fibril in skin; medium, diffuse; arranged in zone like

bands, surrounding area

unstained

As in P. vivax

Pigment (i) Fine granular (ii) Light

brown to yellow brown

(iii) Scattered throughout

cytoplasm

(i) Fine granular

(ii) Blackish

(ii) Scattered throughout.

(i) Coarse granular (ii) Dark

brown (iii) Scattered and

also aggregated in chunks

and masses

Macrogametocyte (female)

Size Large (12 to 14 µ; larger

than male); fills enlarged

RBC

Larger (10 to 12 µ × 2 to 3 µ)

larger than male; larger than

RBC

Smaller than size of RBC Size of RBC

Shape Round or oval Crescent shaped; ends sharply

rounded or pointed

Round; compact Round; compact

Contd...

Medical Parasitology 135

Contd...

P. vivax P. falciparum P. malariae P. ovale

Cytoplasm Deep blue Deep blue Deep blue Deep blue

Chromatin Condensed into compact

mass; eccentric in position

often surrounded by a halo

Condensed into a small deep

staining compact mass; in position lies in the midst of pigment

(no halo)

As in P. vivax As in P. vivax

Pigment (i) Yellow brown

(ii) Aggregated in small

masses (iii) Arranged at

periphery or wreath-like

(i) Black (ii) Granular or small

clumps (iii) Arranged round the

chromatin masses

(i) Dark brown (ii) and as

in P. vivax; abundant pigment—pigmented parasite

(i) Dark yellow brown;

(ii) and as in P. vivax

Morphology of Malarial Parasites Stained by Leishman of Giemsa

136 Concise Book of Medical Laboratory Technology: Methods and Interpretations Morphology of Malarial Parasites Stained in Thin Films

Contd...

Medical Parasitology 137

Contd...

Contd...

138 Concise Book of Medical Laboratory Technology: Methods and Interpretations Contd...

Medical Parasitology 139

Life Cycle of Malarial Parasites

140 Concise Book of Medical Laboratory Technology: Methods and Interpretations The Pathogenesis of Malaria

Medical Parasitology 141

Pathogenesis of Malaria

1. Acute Phase

142 Concise Book of Medical Laboratory Technology: Methods and Interpretations Pathogenesis of Malaria

2. Chronic Phase

Medical Parasitology 143

Pathogenesis of Malaria

3. Complications and Sequelae

144 Concise Book of Medical Laboratory Technology: Methods and Interpretations Pathogenesis of Malaria

4. Blackwater Fever

Acuter hemolytic attacks in MT malarias; associated with

taking of quinine; numerous theories as to mechanism

Medical Parasitology 145

BLOOD FLAGELLATES OF MAN (TABLES 8.3 AND 8.4)

TABLE 8.3: Blood flagellates of man

Prevalence depends upon presence of vertebrate reservoirs and proper insect hosts and varies with human habitation, habits, and

agricultural practices

Parasite and distribution Fly host Enters man Life cycle in man Exit Cycle in fly Reservoir host*

Leishmania donovani

Asia, Africa, tropical

South America, Middle

East, Mediterranean

basin

Phlebotomus

or Lutzomyia

(Sandfly)

Plug of

promastigotes

(leptomonad)

injected with bite

of fly

Become amastigotes

(leishmania or LD

bodies) in RES

macrophages

Sucked

into fly with

blood of host

Become

promastigotes

(leptomonads)

in the intestine

of fly

Man, dogs,

foxes or other

carnivores, wild

rodents

Leishmania tropica

Asia, South and Central

America, Middle East,

Europe

Phlebotomus

or Lutzomyia

(Sandfly)

-do- Become amastigotes

in endothelial cells

of skin

-do- -do- Man, various

wild rodents,

possibly dogs

Leishmania braziliensis

Central and South

America

Lutzomyia

(Sandfly)

-do- Become amastigotes

in endothelial

cells of skin and

secondarily in

mucous membranes

of nasopharynx

-do- -do- Man, various

wild rodents,

possibly dogs

Trypanosoma

gambiense

Central and West Africa

Glossina

palpalis

(Tsetse fly)

Fly bites;

metacyclic

trypomastigotes

(trypanosomes)

injected with

saliva

Trypomastigotes in

lymph and blood;

later in spinal fluid

-do- Become

epimastigotes

(crithidia) and

then metacyclic

trypomastigotes

in the intestine

and salivary

glands of fly

Man, domestic

animals

Trypanosoma

rhodesiense

Central and East Africa

Glossina

morsitans

(Tsetse fly)

-do- -do- -do- -do- Man, wild

game animals

(antelopes)

Trypanosoma cruzi

Central and South

America

Panstrongylus

megistus

(kissing bug)

and other

reduvid bugs

Metacyclic

trypomastigotes

in feces

scratched into

skin or rubbed

into mucous

membrane of eye

Become amastigotes

in tissue cell

(particularly cardiac

muscle) and

trypomastigotes in

bloodstream

Sucked into

bug with

blood of host

Become

epimastigotes

and then

metacyclic

trypomastigotes

in the hind

intestine of bug

Man, dogs,

cats, foxes,

armadillo,

opossum,

rodents

*Varies in each area, in India and Africa, the dog apparently is not involved in L. donovani transmission. RES = Reticuloendothelial system.

146 Concise Book of Medical Laboratory Technology: Methods and Interpretations TABLE 8.4: Blood flagellate diseases of man

Disease and etiology Clinical features Laboratory diagnosis

Kala-azar

(visceral leishmaniasis)