Q: Which of the following is the correct formula for calculating the FC:FS ratio used to determine the source of faecal contamination?

$$FC:FS = \frac{\text{Number of faecal coliforms}}{\text{Number of faecal streptococci}}$$

Question 1

Which of the following best describes a waterborne disease?

Accepted Answer

A disease caused by ingestion of water contaminated with faecal matter or urine.

Question 2

A community experiences an outbreak of cholera after heavy rainfall. Which of the following is the most likely explanation for this outbreak?

Accepted Answer

Contamination of groundwater with sewage carrying Vibrio cholerae.

Question 3

Which laboratory method is most appropriate for quantifying enterococci in a water sample?

Accepted Answer

Membrane filtration on mEnterococcus agar.

Question 4

A water sample has a faecal coliform (FC) to faecal streptococci (FS) ratio of 5. What does this indicate about the source of contamination?

Accepted Answer

The contamination is likely from human sources.

Question 5

Which of the following is NOT a trait that makes waterborne pathogens successful in causing disease outbreaks?

Accepted Answer

Requirement for high infectious dose to cause disease.

Question 6

A patient presents with severe abdominal pain, vomiting, and a worm in their stool. Microscopy reveals large, oval eggs. Which organism is most likely responsible?

Accepted Answer

Ascaris lumbricoides

Question 7

Which of the following drugs is considered the treatment of choice for schistosomiasis?

Accepted Answer

Praziquantel

Question 8

Which indicator organism is most useful for detecting recent faecal contamination in water?

Accepted Answer

Enterococci

Question 9

A water sample is tested for E. coli using a presence-absence method based on enzyme detection. Which enzyme is detected to confirm E. coli?

Accepted Answer

\beta-glucuronidase

Question 10

Which of the following best describes the life cycle of Schistosoma species?

Accepted Answer

Eggs hatch in water, miracidia infect snails, cercariae released and penetrate human skin.

Question 11

Which of the following is a water-based disease requiring an aquatic intermediate host?

Accepted Answer

Schistosomiasis

Question 12

A hospital experiences an outbreak of Legionnaires’ disease. Which of the following is the most likely source?

Accepted Answer

Aerosols from showers or air conditioning systems

Question 13

Which of the following statements about Giardia lamblia is TRUE?

Accepted Answer

It is a protozoan that forms cysts and causes waterborne disease.

Question 14

Which of the following is the correct formula for calculating the FC:FS ratio used to determine the source of faecal contamination?

Accepted Answer

$$FC:FS = \frac{	ext{Number of faecal coliforms}}{	ext{Number of faecal streptococci}}$$

Question 15

Which of the following is a key reason why routine monitoring of all pathogens in water is not practical?

Accepted Answer

There are too many different pathogens to monitor individually.

Question 16

A water sample from a reservoir shows high levels of sulphate-reducing clostridia but no E. coli or enterococci. What does this suggest about the contamination?

Accepted Answer

Remote or intermittent faecal contamination.

Question 17

Which of the following is a major protozoan pathogen associated with waterborne outbreaks and is known for causing a large outbreak in Milwaukee in 1993?

Accepted Answer

Cryptosporidium hominis

Question 18

Which of the following is a recommended point-of-use technique for controlling opportunistic pathogens in drinking water?

Accepted Answer

UV sterilization

Question 19

Which of the following is a characteristic of water-washed diseases?

Accepted Answer

They are caused by poor personal hygiene due to water shortages.

Question 20

A sample of bottled water is tested for microbial contamination. According to the Drinking Water Directive, what is the maximum allowable concentration of E. coli per 250 mL?

Accepted Answer

0/250 mL

Water Contamination and Its Implications in Environmental Microbiology

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