MODULE 7 - Habitat and Transmission

Question 1

Humans are the only reservoir for MTB, which generally infects the lungs, as facultative intracellular parasites in alveolar macrophages. But, they can also affect other parts of the body.

Answer 1

Mycobacterium tuberculosis

Question 2

Transmission is by inhalation of droplet nuclei from a person with active disease in the lungs. It is estimated that less than 10 bacilli may initiate a pulmonary infection in a susceptible individual.

Answer 2

Mycobacterium tuberculosis

Question 3

are propelled into the air when infectious person coughs, sneezes, sings, talks, or spits, or during respiratory manipulations such as bronchoscopy. They are more than 5 µm in diameter, so they immediately settle
out of air. When inhaled, they become lodged in the upper respiratory tract (the nose and throat), where infection is unlikely to develop. However, the smaller droplet nuclei, which are the dried-out residuals of droplets, may reach the alveoli, where
infection begins.

Answer 3

Droplets containing tubercle bacilli

Question 4

Humans are the only natural host of

Answer 4

T. pallidum subspecies pallidum

Question 5

Transmission pf Treponema pallidum occurs by the following routes

Answer 5

i. Direct contact with active lesions
ii. Vertical transmission across the placenta
iii. Other routes of transmission includes:
‣ Nonsexual contact with an active lesion
‣ Transfusion of fresh blood products (< 48 hours of storage)
‣ Accidental needle stic

Question 6

how much treponemes are required for infection?

Answer 6

<60

Question 7

Habitat is the mucous surfaces of the human respiratory tract (upper
respiratory and bronchial epithelial cells) and associated with disease.

Answer 7

Mycoplasma pneumoniae

Question 8

Transmission is by inhalation of infectious respiratory droplets.

Answer 8

Mycoplasma pneumoniae

Question 9

Humans are the sole reservoir; In infected individuals, it is inhabiting skin (sparing warm areas such as armpit, groin and perineum), and the superficial nerves. It is intracellular typically within skin histiocytes and endothelial cells and the Schwann cells of the peripheral nerves

Answer 9

Mycobacterium leprae

Question 10

Genetically identical species have also been isolated form [?] that develop a granulomatous disease similar to leprosy

Answer 10

armadillos

Question 11

Spread from person-to-person requires prolonged contact with infected person. The most common mode of transmission is by inhalation of infectious aerosols from nasal secretions, and less commonly by skin contact with skin lesions.

Answer 11

Mycobacterium leprae

Question 12

found in soil and organic
material worldwide and cause disease in many
animals and in fish

Answer 12

nocardiae

Question 13

Infections result either by inhalation of the
organism from soil or dust or following trauma and
contact with contaminated soil

Answer 13

nocardiae

Question 14

s a louse-borne borrelia which has a world wide distribution although it once became more common in South America, Europe, Africa, and Asia

Answer 14

B. recurrentis

Question 15

B. recurrentis s transmitted via the body louse, [?], which carries the borreliae in its body cavity.

Answer 15

Pediculus humanus

Question 16

Transmission occurs when the infected lice are crushed and scratched into skin

Answer 16

B. recurrentis

Question 17

Humans are the only known reservoir of this louse-borne borrelia

Answer 17

B. recurrentis

Question 18

is widely distributed throughout the world. It is
transmitted by a large variety of soft ticks of the genus Ornithodoros. Transfer from the vector to a vertebrate host takes place via infected saliva during tick attachment

Answer 18

B. hermsii

Question 19

Borrelia hermsii,
the cause of relapsing
fever in the western United
States, is transmitted by

Answer 19

Ornithodoros hermsii

Question 20

The species name of the
[?] genus is often the
same as that of the tick

Answer 20

Borrelia

Question 21

responsible for transmission of endemic relapsing fever

Borrelia

Answer 21

“soft tick”

Question 22

Other causes of tickborne relapsing fever include

Answer 22

Borrelia cuttonia

B. parkeri.

Question 23

has been documented in North and West America, Asia, and in Europe

Answer 23

B. burgdorferi

Question 24

constitute the main

animal reservoirs of B. burgdorferi, but other rodents and birds may also be infected

Answer 24

Mice and deer

Question 25

is primarily transmitted by bites of hard ticks of the genus Ixodes, species of which may vary as determined by their geographical distribution

Answer 25

B. burgdorferi

Question 26

Borreliella burgdorferi was

named after its discoverer

Answer 26

Dr. Willy Burgdorfer

Question 27

has a world wide distribution. Rats,
mice, wild rodents, dogs, swine, and cattle are the
principal sources

Answer 27

Leptospira interrogans

Question 28

L. interrogans in bodies of water contaminated

with animal urine enter through breaks in the

Answer 28

skin

mucous membranes

Question 29

Persons working with animals or in rat-infested surroundings or those most likely to come in contact with water contaminated by rats (eg, miners, sewer
workers, farmers, and fishermen) run the greatest risk of infection.

Answer 29

Leptospira interrogans

Question 30

The species name of the organism has been associated with its characteristics bent or “question mark” ends.

Answer 30

Leptospira interrogans

Question 31

spread primarily through sexual contact

Answer 31

genital mycoplasmas

Question 32

Transmission to man is via the gastrointestinal tract, but transmission via the respiratory tract is also possible.

Answer 32

Mycobacterium avium complex (MAC)