The parasite fauna of two populations of feral pigeons from North and South Trinidad [abstract]

Two populations of feral pigeons (Columba livia) from two locations in Trinidad were examined for their internal and external parasites. Twenty-five birds were live-captured from the Eric Williams Medical Sciences Complex (EWMSC) while twenty were captured in San Fernando. Microscopic examination of blood smears for haemoparasites revealed that both populations had high infection rates of Plasmodium and Haemoproteus and relatively low infection rates of Toxoplasma. Examination of faecal samples revealed that a high proportion of birds were infected with with coccidia, reaching 100 percent in birds from the EWMSC. Other gastrointestinal parasites observed included Capillaria, Ascardia and termatodes. All birds from both localities had high burdens of lice, mite and pigeon fly infestations. The significnce of these results in relation to the role of wild pigeons as reservoirs of pathogens affecting the poultry industry and in the transmission of zoonotic diseases is discussed. (AU)

Comparison of fusional ranges measured by Risley prisms, vectograms, and computer orthopter.

Maximum base-in (BI) and base-out (BO) fusion vergence ranges were measured in 38 normal subjects using 3 different clinical procedures. These procedures used different instruments, instructions, and vergence stimuli (Risley prisms, vectograms, and video-displayed contour and random dot stereograms) presented at 50.8 cm. Test-retest measures, which were taken on each test for each subject, indicated high positive correlations between test and retest measures for most vergence tests. Paired inter-test correlations among five different tests varied as a function of the pairing as well as type of measure taken (BI, BO, break, recovery). It was concluded that different methods of measuring vergence provide different kinds of information and such tests may not be used interchangeably.