Which of the following hosts would be most resistant to infection by enterohemorrhagic Escherichia coli (EHEC)?

• A. Pigs
• B. Cattle
• C. Sheep
• D. Humans

Answer: (B)

Verified step by step guidance

1. Understand the nature of enterohemorrhagic Escherichia coli (EHEC), which is a pathogenic strain of E. coli that primarily colonizes the intestines of certain animals without causing disease in them, but can cause severe illness in humans.
2. Recognize that EHEC is commonly found in the gastrointestinal tracts of ruminant animals, especially cattle, where it acts as a natural reservoir. This means cattle carry the bacteria without showing symptoms, making them less susceptible to infection.
3. Consider the host specificity and susceptibility: pigs, sheep, and humans are generally more susceptible to infection and disease caused by EHEC, whereas cattle have evolved mechanisms to tolerate or resist the pathogenic effects of EHEC.
4. Analyze the ecological relationship: since cattle are the primary reservoir, they are most resistant to infection by EHEC compared to pigs, sheep, or humans, who are more likely to develop symptoms upon exposure.
5. Conclude that among the given options, cattle would be the most resistant host to infection by enterohemorrhagic Escherichia coli (EHEC) due to their role as asymptomatic carriers.