Mathematical Calculation of Expected Malaria Cases
Using the provided predictive formula with the given environmental parameters, the expected number of malaria cases is 171, which does not match any of the provided answer choices (A-150, B-185, C-200, D-135).
Step-by-Step Calculation
The formula provided is: Expected cases = 5 + (0.2 × temperature) + (1.2 × rainfall) + (0.5 × humidity)
Substituting the given values:
- Temperature = 30°C
- Rainfall = 100 mm
- Humidity = 80%
Calculation:
- Expected cases = 5 + (0.2 × 30) + (1.2 × 100) + (0.5 × 80)
- Expected cases = 5 + 6 + 120 + 40
- Expected cases = 171
Clinical Context of Environmental Predictors
While this mathematical exercise yields 171 cases, it's important to understand the epidemiological basis for such predictive models:
Temperature effects: Temperature directly affects mosquito development from egg to adult and the extrinsic incubation period of the parasite within the mosquito, with mosquito biting rates and gonotrophic processes being temperature-dependent 1
Rainfall impact: Rainfall contributes to the proliferation of Anopheles mosquito breeding sites, though heavy rainfall events can conversely cause "washing-out" of breeding sites 1
Humidity influence: Combined with temperature and rainfall, humidity creates the environmental conditions that determine vectorial capacity and disease transmission potential 1
Important Caveats
The relationships between climatic factors and malaria transmission are complex and multi-faceted, with mosquito growth, survival, and disease transmission potential restricted above or below certain temperature thresholds 1. Optimum ranges for climatic suitability vary according to vector species, pathogen, and region, with disease transmission further influenced by social and ecological factors beyond simple environmental parameters 1.
Given that the calculated answer (171) does not match any provided option, there may be an error in the question stem, the formula provided, or the answer choices themselves.