Gce Model Questions Vol1 2019 Agricultural Science Question 25

Practice objective / multiple choice question 25 from the 2019 Gce Model Questions Vol1 Agricultural Science examination.

Gce Model Questions Vol1 2019 Agricultural Science Objective / Multiple Choice Medium Difficulty
Question 25 GCE_MODEL_QUESTIONS_VOL1 • 2019 • AGRICULTURAL_SCIENCE • objective

In a poultry farm an outbreak of Newcastle disease shows the following weekly new case numbers: Week 1 = 5, Week 2 = 12, Week 3 = 28, Week 4 = 65. Assuming the disease follows the discrete exponential model \(C_{t+1}=R_{0}\,C_{t}\), where \(C_{t}\) is the number of cases in week \(t\):\n(a) Estimate the basic reproduction number \(R_{0}\) from the data.\n(b) If a vaccination programme reduces the effective reproduction number to \(R_{e}=0.8\,R_{0}\), how many weeks will it take for the number of cases to fall below 1, starting from the initial 5 cases?\n(c) Discuss one management strategy that could achieve the required reduction.

Answer Options

A. R₀ ≈ 2.10; with Re = 1.68 the cases will never fall below 1, so vaccination must reduce Re below 1 (e.g., achieve >40 % effective coverage).
B. R₀ ≈ 3.00; with Re = 2.40 the cases will never fall below 1, so vaccination must reduce Re below 1 (e.g., achieve >66 % effective coverage).
Correct Answer C. R₀ ≈ 2.35; with Re = 1.88 the cases will never fall below 1, so vaccination must reduce Re below 1 (e.g., achieve >57 % effective coverage).
D. R₀ ≈ 1.90; with Re = 1.52 the cases will fall below 1 after about 4 weeks, so vaccination need not be higher.
Correct Answer
C
Correct Option:
R₀ ≈ 2.35; with Re = 1.88 the cases will never fall below 1, so vaccination must reduce Re below 1 (e.g., achieve >57 % effective coverage).

About This Question

This is Gce Model Questions Vol1 2019 Agricultural Science Question 25. It is one of the objective questions from the 2019 Gce Model Questions Vol1 Agricultural Science examination.

Difficulty level: Medium .

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