18. Protozoa (Cryptosporidium)

Question 1

why study Cryptosporidium? (3)

Answer 1

1. Its importance as a water pollutant.
2. A remarkable opportunist, taking advantages of the defective immune system of its host.
3. Emerging or Re-emerging disease?

Question 2

what are the types of emerging diseases?

Answer 2

1. Not occurred in humans before -This type is difficult to establish and probably rare.
2. Occurred previously but affected only small numbers of people in isolated places.
3. Occurred throughout human history but have only recently been recognized as distinct diseases.

Question 3

what are re-emerging diseases?

Answer 3

Diseases that once were major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population

Question 4

what is an example of an emerging disease that was not seen in humans before? (#1)

Answer 4

Ebola - hemorrhagic fever

Question 5

what are 2 examples of emerging diseases that occurred previously but only affected small numbers before (#2)

Answer 5

Lyme borreliosis

AIDS

Question 6

what is an example of a disease that has occurred in human history but had only been recognized as a distinct disease? (#3)

Answer 6

Cholera

Pandemic influenza

Question 7

what group of emerging diseases does Zika fall into?

Answer 7

2 - emerging diseases that occurred previously but only affected small numbers before

Question 8

what is the association with Zika that caused the CDC to issue a travel alert to several countries in South America including Mexico?

Answer 8

Microcephaly in neonates infected trans-placentally

Question 9

how is Zika transmitted?

Answer 9

through the bite of the Aedes mosquito

Question 10

what is the phylum of Cryptosporidium?

Answer 10

Apicomplexa

Question 11

what are Coccidia?

Answer 11

a group known as the apicomplexa (phylum)

Question 12

what are the 3 different niches of coccidia?

Answer 12

1. The species of coccidia developing in the gastrointestinal tract of vertebrates
2. Those developing extra intestinal
3. Vector-borne

Question 13

what is the hallmark of the apicomplexa?

Answer 13

lack of axonemal locomotive structure

Question 14

what is the hallmark of Myzozoa?

Answer 14

they feed through myzocytosis (sucking)

Question 15

what is the hallmark of alveolata?

Answer 15

having a cavity - it means organisms with cavities

Question 16

how many predominantly distinct genotypes are there of C. parvum, seen in humans?

Answer 16

2

Question 17

what is the infective stage of C. parvum?

Answer 17

oocysts

Question 18

where is the infective stage of C. parvum found?

Answer 18

in the environment

Question 19

what is the vegetative stage of C. parvum?

Answer 19

sporozoites

Question 20

what does the vegetative stage of C. parvum cause?

Answer 20

the pathology

Question 21

what is the asexual life cycle of C. parvum?

Answer 21

a) Oocysts excyst in the small intestine
b) The 8 sporozoites attach to the villi
c) Trophozoites reproduce asexually (schizogony)
d) Develop into type 1 meronts
e) Containing 8 merozoites (Some can cause autoinfection)

Question 22

what is the sexual life cycle of C. parvum?

Answer 22

f) Other meronts become type II meronts containing 4 type II merozoites developing into
g) Microgamonts ♂
h) Macrogamonts ♀
i) Zygotes develop into oocysts
j) Some have thick walls and are excreted in the environment
k) Some have thin walls and reinfect the host

Question 23

what is the machinery for penetrating the host cell?

Answer 23

the apical complex

Question 24

what does the oocyst have at the end on the wall?

Answer 24

a suture

Question 25

what is the use of the suture on the wall of the oocyst?

Answer 25

The suture dissolves during excystation, opening the wall to 4 sporocysts each containing 2 sporozoites

Question 26

by what route is C. parvum transmitted?

Answer 26

the fecal oral route

Question 27

is Crypto a zoonosis?

Answer 27

yes

Question 28

is C. parvum host-specific?

Answer 28

non

Question 29

what can increase transmission of C. parvum?

Answer 29

Person-to-person contacts Person-to-animal contacts Using water for drinking or recreational purposes

Question 30

what contributes to the pathology of C. parvum?

Answer 30

1. Metabolites secreted by Cryptosporidium. 2. Inhibition of glucose-stimulation affecting Na absorption. 3. Increase production of mucosal prostaglandin which can inhibit NaCl absorption leading to secretory diarrhea. 4. Leukocytes can produce high levels of prostaglandins. 5. Alterations in intestinal permeability due to the immune response to the parasite. i.e.: Increased secretions of cytokines like IFN-gamma and transforming growth factor (TGF).

Question 31

which groups are at risk for C. parvum infection?

Answer 31

- workers: - verinarians - farmers - medical professionals - day-care centers - immunodeficient people

Question 32

what are social factors that increase risk for C. parvum?

Answer 32

``` Social Factors: Family Sexual activities Children (day care) Pet’s owner Travelers Drinking non-filtered water ```

Question 33

what are the necessary steps of water analysis for C. parvum?

Answer 33

- At least 50 liters of water must be filtered (1 micron porosity) - Wash the filter with water - Centrifugation - Staining - Microscope - Efficacy about 6.3%

Question 34

what are the new detection methods for C. parvum?

Answer 34

1. Antibody-based (ELISA) | 2. DNA-based (PCR)

Question 35

what are the issues with the "new" methods

Answer 35

- Both tests suffer from non-specificity (other species and other agents). - Both are expensive. - Neither necessarily distinguishes viable from non-viable oocysts.

Question 36

where does Crypto reside in the intestine?

Answer 36

at the apical surface of the intestinal epithelial cells and doesnt invade the deeper layers

Question 37

which branch of the immne system is stimulated by moderate to severe infections?

Answer 37

both, innate and aquired branches

Question 38

what is observed in mucosal infection?

Answer 38

the presence of macrophages and neutrophils at the site of infection

Question 39

why is Crypto such a threat to surface water and the environment?

Answer 39

because it can be passed between all groups, man/animals/env/imported livestock/domestic animals which increases its abundance in nature

Question 40

what is the supreme art of controlling infectious diseases?

Answer 40

prevention | - Faubert

Question 41

what are the species of apicomplexa inhabiting the intestinal niche?

Answer 41

Eimera Isospora Cyclospora Cryptosporidium

Question 42

which are the species of coccidia inhabiting the extra-intestinal niche?

Answer 42

Neosporia Sarcocystis Toxoplasma

Question 43

which are the species of coccidia which are vector borne?

Answer 43

Plasmodium Babesia Theileria (mosquito and tick vectors)