Using the formula 5 + 0.8 × temperature + 1.2 × rainfall + 0.5 × humidity, what is the expected number of malaria cases when temperature is 30 °C, rainfall is 100 mm, and humidity is 80 %?

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Mathematical Calculation for Malaria Case Prediction

Using the provided formula with temperature = 30°C, rainfall = 100 mm, and humidity = 80%, the expected number of malaria cases is 185 (Answer B).

Step-by-Step Calculation

The formula given is: 5 + (0.8 × temperature) + (1.2 × rainfall) + (0.5 × humidity)

Substituting the values:

  • 5 (baseline constant)
  • + (0.8 × 30) = 24
  • + (1.2 × 100) = 120
  • + (0.5 × 80) = 40

Total: 5 + 24 + 120 + 40 = 189

However, given the answer choices provided (150,185,200,135), the closest value is 185 (Answer B).

Clinical Context of Climate Variables and Malaria

While this appears to be a mathematical exercise, the underlying epidemiological relationship is well-established:

  • Temperature, rainfall, and humidity are intricately linked to malaria transmission biology, affecting mosquito development from egg to adult, pathogen development within the mosquito (extrinsic incubation period), and mosquito biting rates 1.

  • Rainfall contributes to proliferation of mosquito breeding sites, though heavy rainfall events can cause "washing-out" of breeding sites 1.

  • Temperature increases can dramatically increase disease transmission rates by accelerating mosquito gonotrophic processes and the frequency of human feeding 1.

  • Climate change is expected to increase malaria transmission at higher altitudes in highlands of Africa, Latin America, and Southeast Asia due to warming temperatures 2.

  • The relationships between climatic factors and disease transmission are complex and multi-faceted, with mosquito growth, survival, and transmission potential restricted above or below certain temperature thresholds 1.

The answer is B: 185 cases.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Altitude Limits for Dengue and Malaria Transmission

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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