Dynamics of infestation by Rhinoestrus usbekistanicus in donkeys (Equus asinus) in Tunisia.

Examination of a total of 125 slaughtered donkeys in Tunisian slaughterhouses revealed the presence of 1,508 larvae of Rhinoestrus usbekistanicus in their nasal cavities, with an overall infestation prevalence of 52.8%. The highest overall intensity (number of larvae per infested donkey) and abundance (number of larvae per donkey examined) of infestation were reported in winter (35.6 and 12.1, respectively). Larvae 1 (L1) were the most frequent stage and reached a peak prevalence of 100% during November. The number of larvae 2 (L2) and 3 (L3) was low and the maximum was recorded during March and April. Post-mortem observations showed that infestation intensity increases with age. The ethmoid bone was the most frequently infected portion of the nasal cavity (83.75%). This is the first study on nasal bots in donkeys in Tunisia.