Trypanosomiasis 'risk' or 'challenge': a review.

Area of Science:

• Veterinary Entomology
• Epidemiology
• Parasitology

Background:

• African trypanosomiases pose significant threats to human and animal health.
• Understanding the 'challenge' posed by tsetse flies is crucial for disease control strategies.
• Previous studies have explored factors influencing disease transmission.

Purpose of the Study:

• To review and define 'challenge' in the context of African trypanosomiases.
• To analyze the relationship between tsetse fly parameters and trypanosomiasis incidence.
• To evaluate the economic viability of different cattle breeds under varying challenge levels.

Main Methods:

• Analysis of incidence data from West and East African sites.
• Correlation analysis between tsetse fly Apparent Density, infection rates, and human/animal trypanosomiasis.
• Evaluation of Berenil's prophylactic effect in cattle.
• Statistical modeling to determine relationships between challenge and infection probability.

Main Results:

• Linear relationships observed between trypanosomiasis incidence and man-tsetse contact or Apparent Density.
• A linear relationship found between cattle Berenil Index and the logarithm of challenge (Apparent Density x fly infection rate).
• Apparent Density is a variable component of challenge; tsetse fly density explains ~50% of its variability.
• Berenil provides approximately 22 days of prophylaxis in cattle.
• A direct, linear relationship exists between daily cattle infection probability and total challenge after accounting for prophylaxis.

Conclusions:

• Tsetse fly density and infection rates are key determinants of African trypanosomiasis challenge.
• Trypanotolerant cattle show potential economic advantages over drug-treated zebus in high-challenge environments.
• The effectiveness of tsetse control measures remains critical for sustainable cattle farming in endemic areas.