Human African trypanosomiasis and Leishmaniasis Flashcards Preview

Infection and Immunity > Human African trypanosomiasis and Leishmaniasis > Flashcards

Flashcards in Human African trypanosomiasis and Leishmaniasis Deck (38)
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1
Q

what type of parasite is Kinestoplastida?

A

parasitic protozoa

2
Q

which species of Kiestoplastida infect human?

A
  1. Leishmania species

2. Trypanosoma species

3
Q

parts of the kinestoplastida

A

flagellum, kinetoplast (like cytoplasm) and nucleus

4
Q

do trypanosome species affect only humans?

A

no - they cause disease in both man and animals

5
Q

what species of trypanosomes affect domestic animals?

A

trypanosoma vivid, trypanosoma congolenesl and trypanosoma brucei brucei

6
Q

what species of trypanosoma affect humans?

A

trypanosoma brucei gambiense and trypanosoma brucei rhodesiense

7
Q

which is the vector which transmits human african trypanosomiasis?

A

tsetse fly (glossina)

8
Q

what determines the distribution of african trypanosomiasis?

A

the vector - tsetse fly vector (genus glossina)

9
Q

how are trypanosomes transmitted between people?

A

via the bite of infected tsetse flies

10
Q

what form of disease cause T. b. gambiense?

A

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

11
Q

what form of disease cause T. b. rhodesiense?

A

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

12
Q

how are T. b. gambiense and rhodiense similar?

A

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

13
Q

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

A

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

14
Q

what do late stages of the african trypanosomiasis disease involve?

A

brain disorders including changes to sleep wake patterns - sleeping sickness

15
Q

how do parasites infect the human after an immune response?

A

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.

16
Q

what is the surface of trypanosome covered by?

A

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

17
Q

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

A

they form homodimers

18
Q

how do they form homodimers?

A

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

19
Q

what does the protein coat do?

A

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

20
Q

how many vsg coats do they express at a time?

A

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

21
Q

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

A

on 5 drugs

- suramin, pentamidine, mearsoprol, eflornithine and nifurtimox

22
Q

what are suramin and pentamidine useful for?

A

useful against early stage disease - before invasion of the CNS

23
Q

what are melarsoprol and eflornithine useful for?

A

useful against late stage disease - after CNS invasion

24
Q

how is eflornithine used?

A

in combination with nifurtimox

25
Q

control methods for tsetse flies

A

insecticide spraying, tsetse trapping and sterile male release

26
Q

what causes Leishmaniases?

A

parasitic protozoa of the genus Leishmania

27
Q

how does leishmania affect the body

A

parasites of different species affect different parts of the body

28
Q

types of Leishmaniases

A

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

29
Q

what do leishmania parasites invade?

A

they invade macrophages

30
Q

what do leishmania parasites become after invading the macrophages?

A

they become amastigote forms proliferating inside macrophages

31
Q

how are leishmania parasites transmitted?

A

by tiny bloodsucking sandflies

32
Q

what animals serve as a reservoir host for leishmaniasis?

A

dogs - leishmaniasis is zoonotic

33
Q

stages of leishmaniasis infection ?

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

2. human stages (2,3,4)

34
Q

Human stages of leshmaniasis (after biting of sandfly)

A
  1. promastigotes are phagocytise by macrophages
  2. promastigotes transform into amastigotes inside macrophages
  3. amastigotes multiply in cells (including macrophages) of various tissues
35
Q

sandfly stages of leishmaniasis

A
  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
36
Q

leshmaniasis treatment

A
  • 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)
37
Q

leshmaniasis vaccines?

A

no vaccine currently exists

38
Q

how is cutaneous leishmaniasis treated?

A

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