1452.pdf

SU

SA N L YN N BAR BE E

.

Ap pli

c a

tio n o

f I

n

Vitr o

C

e

l l

Cu

lt

u r e

A

s s a

y t

o

C

r

y p t

o s

p

o

h diu

m

p

a r v um

o o c

_y

st In a c

t i

v a

tio n

_{b y Th}

e rma

l P

r o c e s s e s

₍

U

n

de r

the

dir e c

tio n o

f M

a r

k D

.

So

bs e

y

)

C

r

_{y p t}

o s

_p

o

ri diu

m

is a n

i

m

p

o r

t

a n

t

w a

te r

bo r n e

_p

a

tho

_g

e n a n

d

it

s o o c

_y

sts a r e v e r

_{y p}

e r s

is

te nt

in

th

e e n v

i

r o nme n

t

a n

d

v e r

_y

r e s

is

ta nt t

o c

he

m

ic a

l

dis

in

f

e c

tio

n.

In a

ctiv a

tio n o

f

Cr

y p t

o s

p

o

ri d iu

m

p

a r v um o o c

_y

s

ts

b y h

e a

t i

s a

_p

o

te n

tia

l d is

in

f

e c

tio n

p

r o c e s s

f

o r w a

t

e r, w a s

te w a

t

e r a n

d

b

i

o s o

li

ds

.

W

e

s

t

u

d ie

d the

k in e

t ic s a n

d

e x

t

e nt o

f t he r

ma

l in a cti

v a

tio n o

f C

.

p

a r

w

m o o c

y

s

ts

in

bu

ffe r e

d

w a

t

e r a

t

35

° ,

4

9

'

,

5

0

°

,

5 5

"

a n

d

60

°

C,

a n

_d

by th

e rmo

_{ph ili}

c a n a e r o

b i

c

di

_g

e s

ti

o n o

f

c o w ma n u r e a

t 55

°

C

u s

in

_g

mam ma

l ia n c e

ll

c u

lt

u r e

to

_q

u a n

tify

o o c

_y

s

ts

in

fe c

ti

v

ity

.

Co

m

p

a r

i

s o n s o

f i

n

fe c

tio u s o o c

y

st

c o n c e n

tr a

tio n s

be

tw e e n u n

tr e at

e

d

c o n

tr o

l

s a n

d the rm

a

lly t

r e a

t

e

d

s am

_{p l}

e s

in

d ic a

t

e

d

s

ig

n

ific a n

t

lo s s e s o

f

o o c

_y

s

t in

f

e ctiv

_{ity by hig h}

e r

te

m

_p

e r a

t

u r e

the r

ma

l t

r e a

t

me n

t in

b

o

th

m

il ie u

.

W hile

t he r e

wer e o n

ly

m

in o r r e

du c

tio n s o

f

o o c

_y

s

t i

n

f

e c

tiv

ity

in

bu

ffe r e

d

w a

t

e r a

ft

e r

24

ho u r s a

t

23

° a n

d 35

°

C,

te

m

_p

e r a

t

u r e s o

f 55

°

a n

d

60

°

C

r e

du c e

d

o o c

_y

st in

fe ctiv

it y by 9

9

.

9%

w

ith in

6

0

m

in u

t

e s.

Ex

p

o s u r e a

t

5 5

°

C

in a n a e r o

bic a

_{lly di g}

e s

t

e

d

ma n u r e

f

o r

60

m

i

n u

te s r e

d

u c e

d

o o c

_y

st in

f

e c

tiv

ity by 9 9

.

9%

,

b

u

t i

n

the u n

t

r e ate

d

ma n u r e o o c

_y

s

t i

nfe c

tiv

ity

w a s s

t

a

b le

fo r

ma n

_{y h}

o u r s a

t 2 3

°

C

.

T h

e s e

d

a

ta

de

mo n str a

t

e

tha

t the

i

n

f

e c

tiv

ity

o

f

C

.

p

a r v um o o c

y

s

ts

is r a

pi dly

a n

d

e x

te n s

iv e

ly

r e

d

u c e

d i

n w a

te r

a n

d b

o v

in e

ma n u r e a

t t he r

mo

_{p hi li}

c

te

m

_p

e r a

tu r e s a s

lo w a s

5 5

°

A C K N OW

L ED G M E NT S

I

w o u

ld l ike

t

o

th

a n

k D

r

M

a rk

So

bs e

_{y fo}

r

hi

s

_g

u

i da n c e a n

d

a

dv

ic e

du r

i

n

_g

_m

_y

s

tu

d y i

n

t he

D

e

_p

a r

tm

e n

t

o

f En v

i

r o nme n

t

a

l S

c

ie n c e s a n

d En

_g

in e e r

in

_g

.

He

h

a s

be e n

m

y

a

dv o c a

te

du r

in

g

e v e r

y

s

te

_p

o

f

m

y g

r a

d

u a

te

t

r a

in

in

_g

, a n

d I

r ema

i

n

I

n a w e o

f h is u n e n

di

n

g k

n o w

le

d g

e a n

d

hi

s a

b

ility t

o

j

u

_{g gl}

e a m

illio n

thi

n

_g

s a

t

o n c e.

I

am

_g

r a

t

e

f

u

l to

Dr

.

M ic

ha e

l A itke n

,

Dr

.

Ge

da

l ia

h S he

la

f

a n

d D

r.

M i ke

Ar r o w o o

d f

o r

t he

i

r

he

_lpf

u

l

a

dv

ic e

, c om me n

ts a n

d

s u

pp

o r

t d

u r

in

g t h

e c o u r s e o

f t his r e s e a r c

h

.

I

w o u

ld

a

ls o

l ike

to

th

a n

k

D

r.

Ric

ha r

d Se e

d fo r c o

m

in

g t

o m

y

a s s

is

t

a n c e a n

d be

in

g

o n e o

f

m

y t

e c

h

n

ic a

l

r e

p

o r

t

r e a

d

e r s a

t the

la s

_{t p}

o s s

i ble

mome n

t

.

I th

a n

k Do u

_g

W

a

it

a n

d D

o r o

_{th y T h}

o m

_p

s o n

f

o r a

lw a

_y

s

be

in

_{g th}

e r e w

h

e n

I

n e e

de

d

t he

m a n

d

p

r o v

idi

n

_g

a n e n v

ir o n

me n

t

w

h

e r e

la

b

o r a

to r

_y

r e s e a r c

h

c o u

l

d p

r o c e e

d

w

it h th

e u

tm

o s

t

e

ffic

i

e n c

_y

.

T

o

a

l l t he

_p

a s

t

a n

d

_p

r e s e n

t l

a

bm

a

t

e s a n

d

s

t

u

_d

e n

t

s, m

y th

a n

k

s

f

o r a

ll t h

e

he

lp

a n

d fr

ie n

ds

hip

a

lo n

g th

e

w a

_y

.

i

e s

_p

e c

ia

lly

a

_pp

r e c

i

a

t

e

t he

lo v

in

_g

s u

_{p p}

o r

t

o

f

m

y h

u s

ba n

d,

J

o

hn

, a n

d d

a u

g

hte r

,

Elle n

.

T he

y

g

a v e me

t he

fr e e

d

om,

ti

me a n

d

lo v e

I

n e e

de

d

to

p

u r s u e

this

d

e

g

r e e.

T h is

_p

r o

_j

e ct w a s s u

_p

_p

o r

te

d b

_{y t h}

e

E

n v

ir o n m e n

t

a

l

S

_y

s

te

ms,

Lim

ite

d

-a s u

bs

idi

a r

_y

o

f the

T A B L E

O

F

C

ON T EN T S

A B

S

T R A C T

i.

A C KN O W L ED

G

M EN T S

ii

.

T A B L

E O

F

CO

N T E NT

S

ii i.

LI

S

T

O

F T A B LE

S

v

i.

L I

S

T

O

F F I

G

U R E

S

v

il

.

C

H A P

T

E

R 1

:

IN T R

O

D

UC

T I

O

N

1

.

C

H A P

T E

R

2

:

LIT ER AT

U

R

E

R E

V

I

E

W

P

a

tho

_g

e n

C

ha r a c

te r

istic s

H i

sto r

_y

3

.

T

a x o n om

_y

4

.

L ife

_{C y}

c

le

5

.

C

r

_{y pt}

o s

_p

o r

idi

o s

is

7

.

T

r a n sm

is s

io n

9

.

W

a

te r

bo r n e

O

u

tb

r e a

k

s

10

.

A

n a

ly

s

is o

f C

r

_{y p t}

o s

_p

o r

i

d

iu

m

C

o n c e n

t

r a

t

i

o n a n

d Re c o v e r

_y

11

.

W

a

t

e r

S

am

_pl

e s

11

.

O

r

_g

a n

ic

S

am

_{p l}

e s -

F

e c e s,

S

l

u

d g

e a n

d Se w a

g

e

1

3

.

P

u r

ific a

tio n

14

.

D

e

t

e ctio n

A

n a

ly

s

is

15

.

I

n

d ic a

t

o r s

1

6

.

M

e

t ho

d

s

f

o r

Ev a

lu a

ti

n

_g

O

o c

_y

s

t V ia

b

_ility

A

n

im

a

l In

fe c

ti

v

_ity

17

.

// I w

fr

o

E

x c

_y

s

ta

ti

o n

1

8

.

V

it

a

l D y

e

S

t

a

i

n

i

n

_g

1

9

.

P

C

R

2

0

.

In v

itr o

C

e

ll

C

u

lt

u r e

A

s s a

_y

20

.

O

c c u r e n c e a n

d

S

o u r c e s o

f

O

o c

_y

s

ts

in

the

E

n v

ir o n

me n

t

S

o u r c e

W

a

t

e r

2 3.

D

rin

k in

_{g W}

a

te r

2 5

.

W

a ste w a

t

e r

2

6

.

Dr

in

k in

_g

Wa

t

e r

T

r e a

t

me n

t

2 8

.

Ph y

s

ic a

l Pr o c e s s e s

29

.

In a c

tiv a

tio n

Pr o c e s s e s

30

.

Wa st

e w a

te r

T

r e a

tm

e n

t

32.

Slu

d g

e

Tr e a

t

me n

t

33

.

Se w a

g

e

Slu

d

_g

e

3

3

.

A

n

i

ma

l W

a ste

35

.

Oo c

y

s

ts

S

u r v

iv a

l i

n

the

En v

i

r o nme n

t

36

.

Sta n

da r

ds a n

d Re

_g

u

la

to r

_y

Co n

t

r o

l

o

f

Oo

c

_y

sts

in

the

En v

i

r o nme n

t

W

a

te r

-

R

a w a n

d F in

is

he

d

39

.

W

a stewa

te r

40

.

Se w a

_g

e

S lu

d g

e

4

0

.

A

n

im

a

l W

a s

te

4 0.

C

HA PT ER

3:

R

ESEA R

CH

OBJ ECT IV ES

42.

C

HA PT ER 4

:

IN IT IA L R ES

EA R

C

H

ON A

C

E LL

CU LT U R E IN F ECT IV IT Y A S

SAY

M E

T H

OD

IN T R

OD U CT ION

4 3

.

M A T E R IA L

S

A N D M ET H O D S

So u r c e a n

d

_p

r o

du c

tio n

C

.

p

a r v um o o c

y

s

t

s

43

.

H

o s

t

c e

lls

-

MD

C

K

c e

ll

c u

ltu r e s

4

4

.

M

o n o c

lo n a

l

a n

ti bo

_{dy p}

r e

_p

a r a

tio n

4 4

.

Oo c

_y

s

_{t p}

r e

_p

a r a

tio n a n

d

e n ume r a

tio n

f

o r e x

_p

e r

im

e n

t

s

4 5

.

M D

C

K in

fe c

tiv

_{it y}

a s s a

_y

o

f Cr

_y

_p

to s

_p

o

ri diu

m o o c

_y

s

t

4 5

.

Da

ta a n a

l

_y

s

is

46

.

R E

S

U LT

S

Effe c

t

o

f in c u

b

a

tio n

tim

e o n

_p

a r a s

ite

de v e

lo

_p

me n

t

o

f

Cr

_{y p t}

o s

_p

o

ri diu

m

liv

i

n

_g

s

ta

_g

e s

4 7

.

D

o s e

-r e s

_p

o n s e r e

la

tio n s

h

ip

o

f the

_q

u a n

t

a

l in vit

r o

i

n

fe c

tiv

ity

a s s a

_y

4

9

.

D ISC

U

SSI

O

N

50

.

C

H A PT ER 5

:

KI

NET I

CS O

F T H ER M A L

IN A

CT IVA

T ION O

F

C

.

PA R VUM OOCY

STS

IN

BUF F

E

RED

WA TE

R

IN T R O D U CT IO N

58

.

M AT E R IA LS

A

ND M

ET H

ODS

So u r c e

,

p

r e

p

a r a

ti

o n, e n ume r a

tio n a n

d i

n

fe c

tiv

itiy

a s s a

y

o

f

Cr

y p

to s

p

o

ri

diu

m

M D

C

K in

fe c

tiv

_ity

a s s a

_y

5 9.

A

s s e s sme n

t

o

f tr

ea

te

d

o o c

_y

s

t

s

60.

R E

S

U LT S

T he rm

a

l In a c

tlv a

tio n o

f C

.

p

a r v um

60

.

D IS C U S S IO N

6 2.

C HA PT E R 6

:

R EC

OV ER Y O F

OO

CYST S F ROM F EC A L M AT ER IA L A N D T H E INA C T IVA T IO N

O F C

.

PA R V

l

/M O

OCY ST S BY T H E R M O PH ILICA L LY A NA E R O BIC S L U DGE D IG EST ION

INT

ROD UCT ION

70

.

MAT

ERI

A L

S

A

N D

M ET

_HODS

So u r c e

, s

tr a

in

,

p

r e

p

a r a

tio n a n

d

e n ume r a

tio n o

f

C

r

y p t

o s

p

o

ri d iu

m

7 1

.

W

a s

te s a

m

_{p l}

e c o

lle c

ti

o n a n

d

_p

r o c e s s

i

n

_g

7 1

.

Se e

di

n

_g

s

tu

die s o n

C

r

_{y p t}

o s

_p

o

ri diu

m r e c o v e r

_{y f}

r om w a ste

72

.

O

_p

e r a

ti

o n o

f

a

be n c

h

,

l

a

bo r a

to r

y

-s c a

le

mo

de

l the r

mo

_{p hili}

c a n a e r o

bi

c

di

_g

e s

t

e r

73

.

Effe c

ts o

f t he r

mo

_{ph ili}

c e x

_p

o s u r e s o n s u r v

iv a

l

o

f Cr

_{y p t}

o s

_p

o

ri diu

m o o c

_y

s

t

s

74

.

M D C K

c e

ll

c u

ltu r e

in

f

e ctiv

ity

a s s a

_y

75

.

Cr

_yp

to s

_p

o

ri d iu

m o o c

_y

s

t i

n

f

e c

ti

v

ity d

e

te r

m

in a

ti

o n

75

.

RESULTS

In

iti

a

l

c

ha r a ct

e riz a

ti

o n o

f

c o w

f

e c e s

7

6

.

O

p

e r a

ti

o n c

h

a r a c

te r

i

stic s o

f

s em

i

-c o n

ti

n u o u s, mo

de

l

a n a e r o

bic

,

th

e rmo

ph ili

c

d

i g

e ste r

7 6

.

Re c o v e r

_y

o

f

o o c

_y

sts

fr o

m w a ste a n

d

c o n

ti

-o

l

s am

p l

e s

7

6

.

As s e s s

me n

t

o

f

tr e a

te

d

oo c

y

sts

7 7

.

D ISC

USS

I

ON

7 8

.

C

H A PT E R V I:

SU

M M A R Y A N D

CO

N

C LU

SI

O

N S

8 5.

R EF ER E NCE

S

86

.

L

I S

T

O

F T A B L

E S

T

a

b le

2 1

L

ev e

l

s o

f C

r

_{y p}

to s

_p

o ri

d

ium

O

o c_ysts

in

Su r

f

a c e an

d G

r o u n

d w

a_te r s 2 7

T

a

b le

2 2 Le v e

l

s o

{ C

r

_{y p}

to s

_p

o ri

d

ium

O

oc_ysts

i

n Dr

_i

n

k i

n

_g

W

ate r 2 7 T a

b le

2 3

O

cc ure nce o

f C

r

_{y p}

to s

_p

o ri

_d

iu

m O

o c_ysts

in

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T i m

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ect o

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M

D C K C

e

l l

C

u

lt

u r e s : En u

m

e r at

i

v e A s s a_y

56

.

F i g

u r e 4

5

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e ct o

f

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l A

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F

_{i g}

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Re_gr e s s

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io n

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p

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S

at 3

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°

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p

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S

at 4 9 °

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l I

n a ct

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v at

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f C

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/

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in

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at

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°

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67

F i g

u r e

5 5

T h

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m

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n a ct

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/

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B

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t

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f C p

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n

PB

S

a n

d

M

a n u r e at

2

3°

C

82

IN T R

OD U C T IO N

Cr

_{y p t}

o s

_p

o

ri diu

m

_p

a r v um r e

_p

r e s e n

ts a

_{hig hly i}

n

fe ctio u s

,eme r

g i

n

g di

s e a s e, e s

p

e c

ia

ll y

amo n

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p

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d in

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ls

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b

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t

n a

t

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f the o o c

y

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lo w

in

fe ct io u s

do s e

c om

b in e

d

w

it h

r e s

ist

a n c e

to c o

m mo n

_ly

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d d is

i

n

fe c

ta n

t

s ma

k

e

th

e_se o r

_g

a n

is

ms

dif fi

c u

lt to c o n

tr o

l

a n

d

a s e r

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t hr e a

t to

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lth

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ts

fo

llo w a

fe c a

l

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l

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t

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d

c a n

be

tr a n s

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itte

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mu

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e s o u r c e s.

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m

pt

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d

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m

pt

oma

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ma n s

p l

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l

a n

d d

ome s

tic

a n

i

ma

l

s c a n s

he

d

o o c

_y

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hic

h

c a n

be c a r r

ie

d int

o w a

t

e r c o u r s e s a n

d

le a

d t

o o u

tb

r e a

ks o

f

e n

t

e ric

d is e a s e

.

T he

US

En v

ir o n

me n

t

a

l Pr o

t

e c

tio n

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_y

(

U SE PA

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,

by th

e

dir e c

tio n o

f the

Sa

fe

W

a

te r

Dr

in

k i

n

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A

c

t

.

pl

a c e

d Cr

y p t

o s

p

o

ri diu

m o n

its

D

r

in

k i

n

g W

a

te r

Pr

io r

ity L i

s

t in

1986

T he

En

h

a n c e

d

Su r

f

a c e

W

a

te r

Tr e a

tm

e n

t Ru

le c u r r e n

_{tl y}

r e

_q

u

ir e s

mo n

ito r

in

_g

o

f th is o r

_g

a n

is

m

by l

a r

g

e u

ti litie s u s

in

_g

s u r

fa c e a n

d g

r o u n

d

w a

t

e r s a s

dir e c

te

d b y th

e r e

_g

u

la

t

o r

_y

n e

_g

o

tia

te

d In

f

o rma

tio n

C

o

lle c

tio n

Ru

le

(

I

C

R

₎

.

In

fo r

ma

ti

o n

g

a

i

n e

d thr o u

gh thi

s s

t

u

d y

w

i ll be u s e

d to

de v e

lo

p

r e

g

u

la

tio n s a n

d

e v a

lu a

te

th

e

e

ffe c

tiv e n e s s o

f tr e a

tm

e n

t

me a s u r e s a n

d

th

e

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t

o

f im

_{p l}

eme n

ti

n

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c o n

tr o

l

me a s u r e s.

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d

e

te c

tio n o

f

o o c

_y

s

t

s

i

s

_{p l}

a

_g

u e

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w

ith p

r o

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ems,

it is e x

p

e c

te

d tha

t

r e

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u

l

a

tio n w

ill

r e

q

u

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t

me n

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to r e

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%

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f

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s

ts

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t

ro

l

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f t his o r

g

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m

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t

ma

d

e

th

r o u

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a

mu

lti

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r o a c

h.

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r s

t b

a r r

ie r

in

_p

r o

te c

ti

n

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r

in

k i

n

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w a

t

e r s o u r c e s

is w a s

t

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t

me n

t

.

Stu

d ie s

ha v e s

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th

a

t

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y

s

t

s a r e

p

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a

t hig h l

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in r a w s e w a

g

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t

r e a

tm

e n

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r o c e s s e s a

lo n e c a n n o

t be r e a

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tic a

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e

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d

u

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to

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t the r e

le a s e o

f

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ts

i

n

to

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me n

t

.

W

a s

te w a

te r

t

r e a

tm

e n

t p

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t

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to

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g

e

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e s,

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t

s

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t he e n v

ir o n

me n

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to

da

t

e

ha v e s

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t ha

t

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ts a r e e

ffe c

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d

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th i

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_{p hili}

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d

me s o

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c r a n

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e, a s e v

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d b y

t he rm

o

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c

d

i

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tio n

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me r

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in

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r e a

tm

e n

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r o c e s s

fo r

mu n

ic

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a

l

s

lu

d

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d

o n e

th

a

t i

s

be

i

n

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d

t

o

tr e a

t

wa s

te a

t

s ome

la r

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a

ir

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a c

il itie s

.

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o a s s e s s

the e

ffe c

tiv e n e s s o

_{f ph y}

s

ic a

l

a n

d

c

he m

ic a

l tr e a

t

me n

_{t p}

r o c e s s o n

th

e v

ia

_{b ility}

o r

in

f

e c

ti

v

_ity

o

f

C

.

p

a r v um

t

hr e e

ba s

ic

me

tho

ds

ha v e

be e n e

m

pl

o

y

e

d

:

1

)

in v

it

r o e x c

y

s

t

a

tio n o

f

o o c

_y

s

ts

,

2

)

v

ita

l d y

e s

t

a

i

n

in

g

(

D A Pl/P I

)

, a n

d 3

)

i

n v

iv o

in

f

e c

ti

o n o

f

a s u

ita

ble a n

im

a

l

mo

de

l

.

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a n

im

a

l

mo

de

ls a r e a c c e

_pt

e

d

a s

t he

"

g

o

ld

s

t

a n

d

a r

d

"

fo r a s s e s s

in

_g

v

ia

b ility

a n

d i

n

f

e c

tiv

ity

,

the

y

a r e

c o s

_tly

a n

d

d

o n o

t

a

lw a

_y

s

_{y i}

e

l d p

r e c

is e

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u a ntita

tiv e

da

t

a.

V ia

bility h

a s

be e n a

d dr e s s e

d b y

a

_p

_p

l ic a

tio n o

f in v

itr o e x c

_y

s

ta

ti

o n a n

d

sta

in

in

_g

w

ith

v

it

a

l d

_y

e s.

Qu e s

ti

o n s r ema

i

n a s

to

t he a

b

i lit y

o

f

t he s e

me

t ho

d

s

t

o

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r e

dic

t i

n

fe cti

v

_ity

r e

lia

_{b ly b}

e c a u s e r e s u

lts a r e o

f te n n o

t

c o r r e

la

t

e

d

w

_{it h}

p

r e

d ic

ti

o n s

fr o

m a n

im

a

l

mo

de

l

s

(

Fi

n c

h

e

t

a

l

,

19

93 & Ko r

ic

h

e

t

a

l,

19 90

)

.

Re c e n

t

a

dv a n c e s

in

in

v

iti

^

o c e

ll

c u

lt

u r e a s s a

_y

me

tho

ds

(

Ar r o w o o

d

e

t

a

l,

1996,

Slifc o e

t

a

l,

1996

)

ma

k

e

th is a n a

tb

-a c

ti

v e

a

lt

e r n a

ti

v e

be c a u s e

t he

_{y p}

r o v

i de

in

fo r

ma

ti

o n o n

t he v

ia

_bility

o

f ti

"

e a

t

e

d

o o c

y

s

t

s a s

de

t

e rm

in e

_{d by}

t he a

_{bil ity t}

o

in

iti

a

t

e

inf

e ctio n a n

d p

r o

life r at

e.

T he a

bil ity t

o

de

te c

t q

u a n

ti t

a

ti

v e

ly t h

e

inf

e c

ti

v

ity

o

f C

.

p

a r v um o o c

_y

s

ts

in c e

ll

c u

lt

u r e

_p

r o v

ide s a c o n v e n

ie n

t to o

l fo r

b

e

tte r

de

te r

m

in a

ti

o n o

f

w a

t

e r,

w a s

t

e w a

te r a n

d

s

l

u

dg

e

t

'

e a

ti

n e nt e

ffe c

ti

v e n e s s a n

d

a s s e s s

in

_g

ris

ks

to

t he

_p

u

b

lic

he a

lt h

.

T he

_p

u r

_p

o s e o

f thi

s s

tu

dy

w a s

t

o e v a

lu a

t

e

the

M

a

di

n

Da r

by

c a n

in e

k id

n e

_y

(

M D

CK

)

c e

ll

c u

ltu r e a s s a

_y

me

tho

d fo r u s e a s a

to o

l fo r

_q

u a n

ti t

a

ti

v e a s s e s sme nt o

f to

'

e a

ti

n e n

t

e

f fic

ie n c

ie s

;

the n

a

_{pp ly thi}

s me

tho

do

lo

_{gy t}

o

_q

u a n

ti

fy th

e r e

du c

ti

o n s o

f

o o c

_y

s

t i

n

f

e c

ti

v

ity i

n

the r

ma

l

_p

r o c e s s e s a n

d

a n a e r o

bic

the rm

o

_{p hili}

c

_{d ig}

e s

te

d

s

lu

_dg

e.

T his s

t

u

d y p

r e s e n

ts

da

ta o n

the

th

e rma

l in a c

ti

va

ti

o n o

f C

.

R EV IEW OF T H

E

L IT ER A T

URE

Pa

t ho g e n

Ch

a r a c

te r

iz a

tio n

H is

t

o r

_y

Cr

_{y p t}

o s

_p

or

idiu

m

_p

a r v um w a s

fi

r s

t

de s c r

ibe

d

a s a n e w s

_p

e c

ie s

in

1912 b

_{y th}

e

A

me r

ic a n

p

a r a s

ito

lo

_{g i}

st Er n e s

t Edw a r

d T y

z z e r

(

T y

z z e r,

19 29

)

.

It

w a s

d isti

n

g

u

is

he

d f

r om

p

r e v

i

o u s

ly id

e ntifie

d

s

_p

e c

i

e s o

f C

r

_{y p t}

o s

_p

o

ri diu

m

by it

s s

iz e

₍

3

-7 p M

)

a n

d it

s r e s

t

ric

tio n

to

the

d ig

e st iv e

tr a c

t

o

f

a s

_y

m

_pt

oma

tic

la

bo r a

to r

_y

m

ic e

.

T y

z z e r '

s

in

itia

l in v e s

tig

a

tio n s o

f this

_g

e n u s o

f p

a r a s

it

e s e

lu c

ida

t

e

d

th

e

d

e

ta

ils o

f the c o

m

_pl

e x

l if

e c

_y

c

l

e o

f this o r

_g

a n

i

sm w

h i

c

h

e v e n

t

o

d

a

_{y h}

o

l

d

s u

_p

a s

th

e

de

fin

itiv e

de s c r

_{i pti}

o n o

f th

e

i

r r e

p

r o

du ctio n

de v e

lo

_p

me n

t

a n

d

mo r

_ph

o

lo

_gy

{

T y

z z e r,

19 07

)

.

R

e

_g

a r

de

d

a s a n o

_pp

o r

tu n

i

s

tic z o o n o s

i

s w

ith l ittle

if

a n

_y

me

dic a

l in

te r e s

t

o r e c o n om

i

c

im

_p

a c

t

₍

C

a s emo r e a n

d Ja c

ks o n

,

19 84 & Sc

hu

ltz

,

198 3

)

,

C

r

y p t

o s

p

o

ri diu

m r e c e

iv e

d

v

i

rtu a

lly

n o

a

tte n

tio n

f

o r mo r e

tha n s

ix

t y y

e a r s a

fte r

it

w a s

dis c o v e r e

d

.

Ev e n

tho u

g h

n ume r o u s r e

p

o rts

c o n

fi

rme

d the

_p

r e s e n c e o

f this

_p

a r a s

ite

i

n ma n

_{y h}

o s

t

s

_p

e c

ie s

it

r ema

i

n e

d

r e

la

tiv e

ly

o

bs c u r e

.

In

1

9

7 1

,

C

.

p

a r v um w a s a s s o c

ia

te

d

w

ith

a c a s e o

f b

o v

i

n e

dia r r

he a a n

d t he

i

n

te r e s

t

o

f the v e

te r

in a r

y

c om mu n

ity

w a s s

tim

u

l

a

te

d

a s

its r o

l

e a s a

_p

a

tho

_g

e n

i

n a n

im

a

ls w a s a

ffir

me

d

.

T he

fi

r s

t de s c r

ip ti

o n

o

f

a

hu

ma n c a s e w a s r e

_p

o r

te

d fiv e

_y

e a r s

la

te r w

he n

In

19 76

a

t hr e e

-y

e a r

-o

ld im m

u n o c om

p

e

t

e n

t

c

hil d fr o

m a r u r a

l fa r m

in

_g

c om mu n

ity

de v e

lo

_p

e

d in

fe c

ti

o n

d

u e

to z o o no

tic

t

r a n sm

is s

io n

₍

N im

e e

t

a

l

. ,

19 76

₎

.

W it hin a

mo nt h, a n o

t he r r e s

id

e n

t

o

f

a

f

a rm

in

g

c o mmu n

ity

w a s

d ia

g

n o s e

d

w

ith

c r

_{y pt}

s

_p

o

ri dio s

is

(

N im

e e

t

a

l

,

19

76 & Me

is e

l

e

t

a

l

,

19 76

)

.

Re

p

o r

ts o

f hu

ma n c r

y pt

o s

p

o r

idio s

is

r ema

in e

d

r a r e u n

til 198

2

w

h

e n

phy

s

i

c

ia n s

thr o u

_gh

o u

t t he

U

n

it

e

d Sta

te s

be

_g

a n r e

_p

o r

tin

_g

a n e v e r

in c r e a s

in

_g

n um

b

e r o

f

c a s e s, e s

p

e c

ia

lly

amo n

g y

o u n

g

ma

le s w

ith

a c

q

u

ir e

d im m

u n o

de

fic

ie n c

y

d is e a s e

,

to

t he

C

e n

t

e r s

fo r

D is e a s e

C

o n

t

r o

l

.

W hile a

p p

a r e n

tly

a s e

lf li

m

it

e

d d is e a s e

in

h

e a

lthy

p

e o

_pl

e,

p

a

tie n

ts w

ith

s u

p p

r e s s e

d im m

u n

itie s c a n

de

ve

lo

p

c

hr o n

ic

in

f

e c

ti

o n s w

ith hi g h

mo r

t

a

lity

r a

te s

.

Sin c e

th

e e a r

ly

80

'

No w a c c e

_p

t

e

d

a s a

_p

r o m

i

n e n

t

a

_g

e nt o

f

d

ia r r

he a

in

l

i uma n s a n

d d

ome stic a

te

d

a n

im

a

l

s

t hr o u

_{g h}

o u

t th

e w o

ri d

,

C

r

y p t

o s

p

o

ri diu

m

is

t he

le a

di

n

g

c a u s e o

f

w a

te r

bo r n e o u

tbr e a

ks

fo r w

hic

h

a n

e

tio

lo

_gi

c a

g

e n

t ha s

be e n

ide n

tifie

d in

t he

Un

ite

d St

a

t

e s

(

Kr a

me r,

19 9

6

)

.

T h

e

C D C

r e c e n

tly

i de n

tifie

d C.

_p

a r v um a s a n eme r

_gi

n

_{g i}

n

fe c

tio u s

dis e a s e

d

u e

to e v

i de n c e s u

_{g g}

e s

t in

g th

a

t it is n e w

ly

s

_p

r e a

d

a n

d

n e w

ly

a

b l

e

t

o c a u s e

life

th

r e a

t

e n

in

_{g d i}

s e a s e.

It

s r o

le

in

th

e e

p id

em

i

c o u

tb

r e a

k i

n

M ilw a u

k

e e

in

1993

_g

e n e r a

t

e

d

mu c

h p

u

blic a

tte n

tio n a n

d

c o n c e r n

f

o r

th

e

_p

o

t

e n

tia

l fo r w a

t

e r

bo r n e

t

r a n sm

is s

io n

.

It

'

s u

biq

u

it

o u s n a

t

u r e, sma

ll

s

i

z e a n

d

a

lo w

i

n

f

e c

tio u s

do s e c o

m

b in e

d

w

ith its r e

la

tiv e

r e s

is

t

a n c e

t

o

ty pi

c a

l

w a

te r

tr e a

t

me n

t p

r o c e s s e s a n

d dis

in

fe c

tio n

ma

ke s

it

o

f p

a rtic u

la r c o n c e r n

t

o

t he

_p

u

b lic

he a

lt h

.

T

a x o n om

y

Cr

_{y p t}

o s

_p

o

ri diu

m

be

lo n

_g

s

t

o

the

_g

e n e r a o

f C

o c c

id

a e

_p

r o

to z o a n

_p

a r a s

ite s

in

t he

_{p hy l}

um

A

_p

ic o

m

_pl

e x a

(

t he s

_p

o r o z o a n s

)

.

T he

mem

be r s o

f this

g

e n u s

de v e

lo

p

w

ith in

t he e

pit h

e

l ia

l

c e

lls o

f

t he

_g

a s

tr o

in

t

e stin a

l

a n

d

r e s

_p

ir a

to r

_{y t}

r a c

ts o

f

v e r

te

b

r a

t

es.

Sp

e c

ie s w

ithi

n

thi

s

g

e n u s c om

p

l

e

te

the

i

r

life c

_y

c

le w

ithin a s

in

_gl

e

h

o s

t

a n

d

ha v e

the s

ma

lle s

t

o o c

_y

sts amo n

_{g th}

e c o c c

id ia

.

A ltho u

g

h

o n c e

c o n s

ide r e

d

s

tr

ic

_{tly h}

o s

t

s

_p

e c

ific

,

the

y

a r e n o w

k

n o w n

t

o

b

e c r o s s

tr a n s

m

is s

ible

(

Pa

y

e r a n

d U

n

g

a r,

1

₉

86

₎

,

be

t

w e e n

diff

e r e n

t ho sts w

ith in

th

e s ame v e r

t

e

b

r a

t

e c

la s s

.

In

itia

_lly

, n ome n c

la

t

u r e w a s

b

a s e

d

o n

t he s

p

e c

ific

ho s

t

-p

a r a s

it

e r e

la

tio n s

hi p

₍

Pa

_y

e r e

t

a

l

,

1

₉

9 0

₎

a n

d

a s ma n

_y

a s

tw e n

ty

-o n e

d

iff

e r e n

t

s

_p

e c

i

e s w e r e

id

e n

tifie

d

.

T

a x o n om

i

c c

l

a s s

ific a

tio n

r ema

in s c o n

f

u s

in

_{g d}

u e

t

o

th

e

la c

k

o

f ho st

s

_p

e c

ific

ity

a n

d Is

t he r e

f

o r e u n

de r r e v

is

io n

.

A t p

r e s e n

t

, s

ix

s

_p

e c

ie s o

f

C

r

_{y p t}

o s

_p

o

ri diu

m a r e a c c e

_p

te

d

(

C

a s emo r e,

1

990

)

;

C

.

p

a r v um

in

fe c

t

s mam ma

ls

,

i

n c

lu

d

i

n

_g

ma n

_;

_C

. mu n s

in

f

e ct r o

d

e n

ts

;

C

.

b

a

ile

y

a n

d C

. me

/e a

g

n

'

cl/s

inf

e c

t

b

ir

d

s;

C

. c r o

fa

// i

n

f

e c

ts

r e

ptil

e s_; a n

d

C

. n a s o r um

in

f

e c

ts

fis

h.

V

a

ri

a

tio n s w

ithi

n

h

o s

t

s

p

e c

if

ic

ity

, s

it

e s o

f in

fe ctio n a n

d

p

a

tho

_g

e n

i

c

ity

ma

_y

e v e n

t

u a

lly l

e a

d to v a

li da

tio n o

f

a

dd itio n a

l

s

_{pe c}

ie s

.

A ltho u

gh

c r o s s

tr a n s

m

is s

io n

do e s o c c u r

,

C

.

p

a r v um

is

the s

p

e c

ie s r e s

p

o n s

ible

fo r

mo s

t hu

ma n a n

d

a n

im

a

l i

n

f

e c

tio n s a n

d it is

t he o n

_ly

w a

te r

bo r n e

C

o c c

i d t

o

in

fe c

t hu

ma n s

(

C

u r

d

s,

1992

)

.

s

_p

o r o z o

ite s

f

r om

h

uma n,

ho r s e a n

d

c a

lf

s o u r c e s.

Fo u r o r

fiv e o

f the s e

is o

la

te s s

ho w e

d

s u

f fic

ie n

t

diffe r e n c e s

i

n

_p

e

_ptid

e

_p

r o

_p

e r

tie s

t

o a

l lo w

ide n

tific a

tio n o

f the

is o

l

a

te

.

Ye

t

,

the r e

is s

till i

n s u

f fic

ie n

t

e v

i

d

e n c e

t ha

t Is o

la

te s c a n

be s u

bd iv

ide

d ba s e

d

o n a n

tig

e n

ic o r o

t he r s u

_btyp

e s

(

Ca s e

mo r e,

198 4

)

.

Ot he r s

t

u

di

e s

h

a v e

id

e n

tifie

d d iffe r e n c e s

be

t

w e e n

is o

la

te s a

t the

_g

e n e

tic a n

_{d p h}

e n o

typi

c

le v e

l,

b

u

t

a r e n '

t

c o n c

lu s

iv e

(

N ic

ho

ls e

t

a

l,

199 0,

Aw

a

d

-

EI

-

Ka rie

m e

t

a

l

,

19 95

,

Ca r r a

wa

y

e

t

a

l,

19 96

)

.

In a r e c e n

t

dis

_p

a

t

c

h i

n

C

D

C

'

s

Em

e r

_g

i

n

_g

I

n

fe c

tio u s

Dis e a s e

_j

o u r n a

l

,

i

n v e s

ti

g

a

to r s

de s c r

ibe

d

a

_g

e n e

tic

_p

o

_ly

mo r

_p

h is

m w

ithi

n

the

T RA P

-

2 g

_{e n e w}

h ic

h

_{m a}

y

a

l lo w

f

o r

th

e

ide n

tific a

t io n o

f th

e s o u r c e o

f

o o c

_y

s

ts

₍

Pe n

_g

e

t

a

l,

199 7

₎

.

T he a u

tho r s r e

p

o r

te

d tha

t b

o v

i

n e a n

d hu

ma n

i

s o

la

te s c a n

be

d is

ti

n

_g

u

is

he

d b

a s e

d

o n

the s e

mo

le c u

la r

te c

hn

i q

u e s.

T his r e

p

r e s e n

ts a s

ig

n

ific a n

t br e a

kt hr o u

g h if

the

_y

a r e a

ble

to v e r

ify th i

s

_p

a

tte r n w

ith fu r

th

e r r e s e a r c

h

.

De

te r

m

in a

tio n o

f

s o u r c e s o

f

o o c

y

sts

is

im

_p

o r

t

a n

t in

th

e

in v e s

_{ti g}

a

tio n o

f f

u

t

u r e o u

tb

r e a

k i

n v e s

ti

_g

a

tio n s a n

d

c o n

tr o

l

e

f fo rt

s.

F i

_g

u r e

2

.

1

T

ax o n om

y

o

f

Cr

y

p

t

o s

p

o

ri d i

u

m

P h y la Sar co m a st igophora

(

a m o eba s,f lagellate s, Entamo eba. G ia rd ia

)

Orde r

Subo rde r Fam ilie s Gene ra

Pr oto z o a A p lc o_{m p l}e x a

(

s_po r o z o a n s

₎

C iliop ho r a

(

ciliate s

)

Eu c o c ci d lo rida

.E imio rin a^., ^ ^ ^

Sa r c o c_yst ida e Cr_{y p t}o s_pori dilda

T

^ Eiin e ii i_da e Sa rc o cyslis,

To x op la sma

Cr_{y p}to s_po rid ium E ime ria, Is o s_po r a

Life

C

y

c

le

Cr

_{yp t}

o s

_p

o r

idiu

m, a mo n e c

io u s

p

a r a s

ite

, c om

p l

e

t

e s

it

s e n

tir e

life c

y

c

le w

ithi

n a s

in

gl

e

ho st

.

It

s

life c

_y

c

le

is s

im

i l

ar

to o

the r

Co c

c

ida e

in

tha

t it

c a n

be

d i

v

ide

d int

o s

ix

dis

tin c

tiv e

_{p h}

a s e s :

e x c

_y

s

t

a

tio n

, me r o

g

o n

y

,

g

ame

to

g

o n

y

,

f

e r

ti l iz a

tio n

, o o c

y

s

t

s w a

ll fo r

ma

ti

o n, a n

d

s

p

o r o

g

o n

y

(

C

u r r e n

t,

198 7

₎

.

I

nfe c

ti

o n

is

in

iti

a

te

d f

o

llo w

in

g i

n

g

e s

ti

o n o

f the

th ic

k

w a

lle

d,

e n v

ir o n

me n

ta

lly

r e s

is

ta nt

o o c

y

s

t

w

hic

h

is s

he

d in

the

fe c e s o r n a s a

l

s e c r e

ti

o n s o

f the

in

fe c

t

e

d

ho s

t

s.

Oo c

y

s

t

s c a n

be

p

r e s e n

t in

c o n

t

am

in a

te

d

fo o

d,

w a

te r o r

the

_g

e n e r a

l

e n vir o nme n

t

a n

d

a r e e x

ti

'

f

r om

t

he o

oc

_y

sts

i

n

the

_g

a str o

i

nte st

in a

l

o r r e s

_{p i}

r ato r

_{y t}

r a c

t

a n

d

in

f

ec

t

e

_p

it he

li

a

l

c e

lls

.

A ll

e n

do

_g

e n o u s s

ta

_g

e s o

f the

_p

a r a s

it

e a r e

fo u n

d

a

t the

lu

m

in a

l

s u rfa c e o

f the e

_{p it h}

e

liu

m.

W hile

a n a

to

m

i

c a

l

s

ite s o

f In

f

e c

tio n u s u a

lly i

n v o

lv e

the a

li

me n

t

a r

_{y t}

r a c

t,

o

the r

mu c o s a

l

s u r

f

a c e s

lin e

d

w

ith

e

_{pit h}

e

lia

l

c e

lls a r e a

ls o

_p

e rm

is s

iv e

t

o

in

fe c

tio n

(

Ca s e

mo r e,

1988

)

.

Ex c

_y

s

ta

tio n

is

tho u

_{g ht t}

o r e s u

lt fr o

m e x

_p

o s u r e

to a c o

m

bin a

tio n o

f bo

dy t

em

_p

e r a

t

u r e,

CO

j,

p

r o

te o

lyt i

c e n z

_y

me s a n

d

bile s a

lts

(

C

u r r e n

t

,

1987

)

.

Up

o n at ta c

h

me n

t

o

f th

e s

p

o r o z o

ite

t

o a c e

ll,

a

f

e e

d

e r o r

_g

a n e

ll

e

de v e

l

o

_p

s

be

t

w e e n

the s

_p

o r o z o

it

e s a n

d

c e

ll

c

_{y t}

o

_p

l

a sm.

T he

p

a r a s

it

e u n

de r

g

o e s

diffe r e n

ti

a

ti

o n w

ithi

n

t he

ho s

t

s

_p

a r a s

it

o

_{p h}

o r o u s v a c u o

le m e

m

br a n e

t

o

fo r

m a n

in

tr a c e

llu

la r

t

r o

_{p h}

o z o

ite

.

As e x u a

l di

v

is

io n

, me r o

go

m

y

, r e s u

lts

in

th

e

f

o rma

tio n o

f ty p

e

I

me r o nts.

T he s e

me r o n

t

s c o n

ta

in s

ix

t

o e

ig ht

me r o z o

it

e s a n

d

c a n

in

fe c

t

a

ho s

t

c e

l l to

de v e

lo

_{p i}

n

t

o a n e w

T yp

e

I

me r o n

t

o r

T yp

e

II

me r o n

t

s.

T yp

e

II

me r o n

t

s u n

d

e r

g

o a s e x u a

l

div

i

s

io n s

t

o

p

r o

du c e

f

o u r me r o z o

ite s

th

a

t g

o o n

to

de v e

lo

_{p i}

n

to

_g

amo n

ts

,

t he s e x u a

l

s

ta

g

e.

A

ma

j

o r

ity

o

f t he

me r o

ite s

fr o

m

T yp

e

II

me r o n

t

s

_g

o o n

t

o

fo r

m ma c r o

_g

ame

ts

(

80%

)

,

the r e

ma

i

n

i

n

g

fo r

m m

ic r o

g

amo n

t

s

(

20%

)

,

t he

f

ema

le

a n

d

ma

le

co u n

te r

_p

a r

ts r e s

_p

e ctiv e

ly

(

Cu r r e n

t

,

1987

)

.

F

e rtil iz a

tio n r e s u

lts

in

the

p

r o

du c

tio n o

f

a z

_{y g}

o

te

th

a

t de v e

lo

_p

s

i

nto e

ithe r

thin o r

th ic

k

w a

lle

d

o o c

_y

ste w

h ic

h

s

_p

o r u

la

te s

in v

iv o

.

Bo

th typ

e s o

f

o o c

_y

st c o n

t

a

in

f

o u r s

_p

o r o z o

it

e s.

M

o st o

f th

e o o c

y

s

ts

p

r o

d

u c e

d

a r e

t hic

k

w a

l le

d

a n

d

a r e s

h

e

d i

n

the

f

e c e s.

T he s e a r e

t he e n v

ir o n

me n

ta

lly

r e s

ist

a n

t fo r

ms

th

at c a n

tr a n s

m

it the

in

fe cti

o n

to o

the r

ho s

t

s

.

T he

thi

nwa

lle

d

o o c

_y

s

t is s u r r o u n

de

d

o n

ly b y

a u n

it

mem

br a n e a n

d

e x c

_y

st w

ith i

n

the

g

a s

t

r o

in

te s

tin a

l tr a c

t

o

f the

ho st

s o o n a

fte r r e

l

e a s e

fi

'

om a

h

o s

t

c e

ll

a n

d

a r e c a

_p

a

ble o

f

r e

in

iti

a

ti

n

_g

the e n

do

_g

e n o u s c

_y

c

le

.

T he

p

o

te n

tia

l fo r r e c

y

c

lin

g

s

p

o r o z o

it

e s

thr o u

gh th

e

g

e n e r a

tio n o

f th i

n w a

ll

e

d

o o c

_y

s

t

s

i

s u n

i

_q

u e

to

t his

_g

r o u

_p

o

f

Co c c

idia

'

s

_p

a r a s

ite s

(

Cu r r e n

t

a n

d

Lo n

_g

,

1

983

)

.

T his

fe a

tu r

e

is

p

r o

ba

bly

r e s

_p

o n s

ib le

f

o r

the

l

o w

i

n

f

e c

ti

v e

do s e r e

_q

u

i

r e

d to

i

n

itia

t

e

in

fe c

tio n a n

d the

_p

e r s

is

te n

t l ife

t hr e a

t

e n

in

_g

i

n

f

e c

tio n

in a

bs e n c e o

f

r e

_p

e a

t

o r a

l

e x

_p

o s u r e o

fte n s e e n

i

n

A ID

S

_p

a

tie n

ts

.

T he

ti

me r e

_q

u

i

r e

d to c o

m

_p

le

t

e

the e n

tir e

lif

e c

_y

c

le o

f this

_p

a r a s

it

e v a r

ie s w

ithi

n

ho s

ts

,

bu

t is

r e

_p

o rte

d to

be

be

tw e e n

18

-

24 ho u r s w

ithi

_n

hu

m

a n s.

T he

p

e r

io

d be

tw e e n

in

f

e c

ti

o n a n

d

o o c

y

s

t

s

he

dd

in

_g

in

h

uma n s v a r

i

e s

fi

s

he

d i

n

f

e c e s a

_pp

e a r s

to

be a s s o c

ia

te

d

w

ith

s e v e r

_ity

o

f

s

y

m

_pt

oms,

b

u

t

a s

y

m

pt

oma

t ic c a r r

ie r s a r e

a

ls o c a

_p

a

b le o

f

s

h

e

d di

n

_g

o o c

_y

s

t

s.

Fi g

u r e

2

.

2

L if

e

C

y

c

le o

f

Cr

y p t

o s

p

o

ri d i

u

m

4 Ho st^p iihali iiV

m rs Gt kH i Inge stio n

I I

Twe ime ran t

Matu r e

o o cyst T Mi elme r aM

Ma c r ogamo nl

C

r

_{y pt}

o s

p

o ri dio s

is

T he e

ffe c

t

o

f in

_g

e stin

_g

C

.

p

a r v um o o c

y

s

t

c a n r a n

g

e

f

r om a s

y

m

pt

oma

tic

i

n

f

e c

tio n

, a

fe w

d

a

_y

s o

f

m

i ld to s e v e r e

dia r r

h

e a, c

ho

le r a

-

lik

e

di

a r r

he a r e

_q

u

ir

in

_g

me

d ic a

l

a

tte n

tio n

,

ho s

pit

a

liz a

tio n

a n

d

_p

o

te n

ti

a

ll

_y

de a

t h

.

T he

mo s

t p

r om

in e n

t

a n

d fr e

q

u e n

tly id

e n

tifie

d

ma n

ife s

ta

tio n o

f

c r

_{y pt}

o s

_p

o rd io s

is

is

_p

r o

f

u s e,w a

te r

y d i

a r r

he a

, a s s o c

ia

te

d

w

ith

v om

itin

g

, a

bd

om

in a

l p

a

in

, a n o r e x

ia

, w e

ig ht l

o s s,

de

hy d

r a

tio n a n

d lo w

g

r a

de

f

e v e r

(

C

u r r e n

t

a n

d Ga r c

i

a,

1991

)

.

Ge n e r a

lly

a s e

lf

-

lim

ite

d

inf

ec

tio n o

f

s

ho r

t

du r a

tio n

in

im m

u n o c om

_p

e

te n

t

v

ic

tim

s,

the s e v e r

ity

a n

d

du r a

tio n o

f the

illn e s s

a

_pp

e a r s

t

o

b

e c o n n e c

te

d to

th

e

im m

u n e s

_y

s

t

em

₍

Un

_g

a r,

19 90

)

.

Sy

m

p t

oms u s u a

lly

o n s e

t

o n e

to

tw o w e e

k

s a

ft

e r e x

_p

o s u r e,

g

e n e r a

lly l

a s

tin

g

be

tw e e n e

ig ht

a n

d tw e n

ty

da

y

s,

bu

t

c a n

b

e c ome