MT2 > Plague Paper Stuff

Question 1

(Madagascar Plague) What molecular techniques did the researchers use to identify Y. pestis biovars?

Answer 1

Pulse Field Gel Electrophoresis, RFLP of 16S rRNA genes.

Question 2

Is Y. pestis gram positive or gram negative?

Answer 2

Gram negative.

Question 3

(Madagascar Plague) Which biovar of Y. pestis was found to have caused the 2017 plague?

Answer 3

Biovar orientalis.

Question 4

(Madagascar Plague) Which ribotype(s) correspond(s) to biovar Orientalis?

Answer 4

Mainly ribotype B, but occasionally ribotype G or E and even once S.

Question 5

(Madagascar Plague) What was the research objective?

Answer 5

To show that:

• Before 1982 ribotype B
• After 1982 ribotype R, Q, & T appeared

Question 6

(Madagascar Plague) How many strains of Y. pestis were isolated between 1939 and 1996?

Answer 6

187 strains.

Question 7

(Madagascar Plague) What enzymes were used to digest Y. pestis DNA prior to hybridization?

Answer 7

EcoR1 and EcoR5.

Question 8

(Madagascar Plague) What is a ribotype?

Answer 8

A way to identify bacteria based on their ribosomal gene (16S rRNA).

Question 9

(Madagascar Plague) What is a pulsotype?

Answer 9

A distinct strain of bacteria as separated by Pulsed-Field Gel Electrophoresis. Genomic DNA.

Question 10

(Madagascar Plague) What can we conclude from finding that ribotypes Q and R share a consistent pulsotype?

Answer 10

That this would have a clonal origin.

Question 11

(Madagascar Plague) How was plague introduced to Madagascar? When?

Answer 11

From India by ship in 1898.

Question 12

(Madagascar Plague) Where in Madagascar is plague endemic?

Answer 12

The high plateau regions of Ambositra and Ambohimasahoa.

Question 13

(Madagascar Plague) Besides ribotyping and pulsotyping, how else can related strains be differentiated?

Answer 13

By analysis of plasmid profiles (plasmid DNA).

Question 14

(Madagascar Plague) How did the three new ribotypes likely develop from the original ribotype B in Madagascar?

Answer 14

Probably subjected to long-term selective pressures in specific ecosystems which was eventually relieved and allowed modification without affecting survival.

Question 15

(Madagascar Plague) What did the researchers conclude about bacterial evolution and strain modification?

Answer 15

Distinct ribotypes can evolve in a short time period even when isolated. Local modifications can explain variation in other parts of the world.

Question 16

(Madagascar Plague) What is a “suspected” case?

Answer 16

Someone who was exposed to an infected individual and may have been infected.

Question 17

(Madagascar Plague) What is a “probable” case?

Answer 17

Someone who has had their symptoms tested by dipstick and found to be positive for the disease.

Question 18

(Madagascar Plague) What is a “confirmed” case?

Answer 18

Someone who has been tested using PCR and is confirmed to be infected with the disease.

Question 19

(Outbreak Investigation) Why might we want to investigate the outbreak of a disease? Just list a couple of reasons.

Answer 19

• Prevent additional cases
• Prevent future outbreaks
• Evaluate prevention strategies
• Address public concerns
• Improve understanding of the disease

Question 20

(Outbreak Investigation) What are the 3 types of activities associated with outbreak investigation?

Answer 20

1. Epidemiological investigation
2. Environmental investigation
3. Interaction with public, press, legal system

Question 21

(Outbreak Investigation) What are some things that might constrain an outbreak investigation? Just list a couple of examples.

Answer 21

• Urgency to find and eliminate source
• Pressure to conclude investigation quickly
• Limited number of cases to study
• Early media reports cause bias
• Legal liability
• Longevity of clinical and environmental samples

Question 22

(Outbreak Investigation) What 10 steps outline an investigation? (ok if you can’t get them all, there’s a fuckton).

Answer 22

1. Establish case definition
2. Confirm cases are real
3. Establish background rate
4. Define scope of outbreak
5. Examine epidemiological features
6. Generate hypotheses
7. Test hypotheses
8. Collect/test environmental samples
9. Implement control measures
10. Inform the public

Question 23

(Outbreak Investigation) What is a case definition? What are the 4 main components?

Answer 23

A way to standardize the classification of cases of interest based on:

1. Person
2. Place
3. Time
4. Clinical features

Question 24

(Outbreak Investigation) What test must a hypothesis pass during an investigation in order to be valid?

Answer 24

The Koch test.