Human African Trypanosomiasis and Leishmaniasis

Question 1

what type of parasite is Kinestoplastida?

Answer 1

parasitic protozoa

Question 2

which species of Kiestoplastida infect human?

Answer 2

1. Leishmania species

2. Trypanosoma species

Question 3

parts of the kinestoplastida

Answer 3

flagellum, kinetoplast (like cytoplasm) and nucleus

Question 4

do trypanosome species affect only humans?

Answer 4

no - they cause disease in both man and animals

Question 5

what species of trypanosomes affect domestic animals?

Answer 5

trypanosoma vivid, trypanosoma congolenesl and trypanosoma brucei brucei

Question 6

what species of trypanosoma affect humans?

Answer 6

trypanosoma brucei gambiense and trypanosoma brucei rhodesiense

Question 7

which is the vector which transmits human african trypanosomiasis?

Answer 7

tsetse fly (glossina)

Question 8

what determines the distribution of african trypanosomiasis?

Answer 8

the vector - tsetse fly vector (genus glossina)

Question 9

how are trypanosomes transmitted between people?

Answer 9

via the bite of infected tsetse flies

Question 10

what form of disease cause T. b. gambiense?

Answer 10

causes a chronic form of the disease - it can pass several years between infection and death
- endemic in west and central africa

Question 11

what form of disease cause T. b. rhodesiense?

Answer 11

causes an acute form of the disease - just weeks between infection and death
- endemic in east and southern africa

Question 12

how are T. b. gambiense and rhodiense similar?

Answer 12

they are morphologically indistinguishable, but they can be differentiated at the DNA level

Question 13

what parts of the body do the parasite injected by the tsetse fly infect in the human body?

Answer 13

the blood and lymphatic systems, later the central nervous system and the brain

Question 14

what do late stages of the african trypanosomiasis disease involve?

Answer 14

brain disorders including changes to sleep wake patterns - sleeping sickness

Question 15

how do parasites infect the human after an immune response?

Answer 15

when the parasite is injected in the human body, it grows for about a week while the immune system confirms their foreign status and then mounts a fatal antibody response.
some parasites change their coat and can grow while the immune system checks again their status, so they can attack again.

Question 16

what is the surface of trypanosome covered by?

Answer 16

is covered in a densely packed “variant surface glycoprotein” (Vsg) coat

Question 17

what do the proteins in the coat covering the trypanosome form?

Answer 17

they form homodimers

Question 18

how do they form homodimers?

Answer 18

they anchor to the membrane via a glycosyl phosphatidyl inositol (dpi) anchor

Question 19

what does the protein coat do?

Answer 19

does not restrict access of low molecular weight solutes to the membrane
it prevents complement proteins fixing at the trypanosome’s plasma membrane

Question 20

how many vsg coats do they express at a time?

Answer 20

they have the potential to express over 1,000 msgs, but express only one at a time with complex gene expression regulation

Question 21

what does the chemotherapy of human african trypanosomiasis (HAT) depend on?

Answer 21

on 5 drugs

- suramin, pentamidine, mearsoprol, eflornithine and nifurtimox

Question 22

what are suramin and pentamidine useful for?

Answer 22

useful against early stage disease - before invasion of the CNS

Question 23

what are melarsoprol and eflornithine useful for?

Answer 23

useful against late stage disease - after CNS invasion

Question 24

how is eflornithine used?

Answer 24

in combination with nifurtimox

Question 25

control methods for tsetse flies

Answer 25

insecticide spraying, tsetse trapping and sterile male release

Question 26

what causes Leishmaniases?

Answer 26

parasitic protozoa of the genus Leishmania

Question 27

how does leishmania affect the body

Answer 27

parasites of different species affect different parts of the body

Question 28

types of Leishmaniases

Answer 28

cutaneous, mucutaneous, visceral, post tala-azar dermal syndrome

Question 29

what do leishmania parasites invade?

Answer 29

they invade macrophages

Question 30

what do leishmania parasites become after invading the macrophages?

Answer 30

they become amastigote forms proliferating inside macrophages

Question 31

how are leishmania parasites transmitted?

Answer 31

by tiny bloodsucking sandflies

Question 32

what animals serve as a reservoir host for leishmaniasis

Answer 32

dogs - leishmaniasis is zoonotic

Question 33

stages of leishmaniasis infection ?

Answer 33

1. sandfly stages (1, 5,6,7,8,)

2. human stages (2,3,4)

Question 34

Human stages of leshmaniasis (after biting of sandfly)

Answer 34

2. promastigotes are phagocytise by macrophages
3. promastigotes transform into amastigotes inside macrophages
4. amastigotes multiply in cells (including macrophages) of various tissues

Question 35

sandfly stages of leishmaniasis

Answer 35

1. sandfly takes a blood meal (injects promastigote stage into the skin)
   - -human is infected–
2. sandfly takes a blood meal (ingests macrophages infected with amastigotes)
3. ingestion of parasitised cell
4. amastigotes transform into promastigote stage in midgut
5. divide in midgut and migrate to proboscis

Question 36

leshmaniasis treatment

Answer 36

• antimony based drugs remain first line (but toxicity and increasing resistance are limiting use)
• amphoteric in B, miltefosine, pentamidine and paromomycin (have variable efficacy depending on species of Leishmania)

Question 37

leshmaniasis vaccines?

Answer 37

no vaccine currently exists

Question 38

how is cutaneous leishmaniasis treated?

Answer 38

this form of infection is usually self-healing, followed by roust immunity thus it is possible vaccines will be possible