Studies on the screwworm fly Cochliomyia hominivorax in Libya: effect of temperature on pupation and eclosion.

The American screwworm fly Cochliomyia hominivorax has recently been reported in Libya (El-Azazy 1989). Fly larvae were cultured on blood agar at different temperatures (-5 degrees, 5 degrees, 18 degrees, 20 degrees, 30 degrees, 37 degrees, or 40 degrees C). Larvae pupated at 18 degrees, 20 degrees, 30 degrees, or 37 degrees C, and the highest pupation (100%) occurred at 20 degrees C. Adult flies emerged from pupae that were maintained at 18 degrees, 20 degrees, 30 degrees, or 37 degrees C; the maximal eclosion (94%) occurred at 20 degrees C. Correlation of these findings with meteorological temperature data from local areas in which C. hominivorax myiasis occurs suggests a crucial role for temperature in the determination of the effective environment for this fly species.

Anticestodal action of oxfendazole on Raillietina tetragona in experimentally infected chickens.

Oxfendazole was tested against Raillietina tetragona in experimentally infected chickens using single oral doses of 20, 10, 7.5, 5, and 2.5 mg/kg body weight. The minimal dose of the drug which produced 100% efficacy against immature worms was 10 mg/kg whereas the same effect on the mature parasite was obtained with 7.5 mg/kg. Doses lower than these significantly reduce worm burdens. The compound appears to be safe for chickens and a dose of 20 mg/kg (twice the recommended dose) produced no untoward clinical reactions.

Anthelmintic activity of praziquantel on Raillietina tetragona in chickens.

Praziquantel was tested against mature (17-day-old) and immature (7-day-old) Raillietina tetragona in experimentally infected chickens using single oral doses of 10, 7.5, 5, or 2.5 mg/kg body wt. The compound showed potent anticestodal activity, with 100% efficacy at 10, 7.5, and 5 mg/kg against immature worms and an efficacy of 100% 97.1%, and 95% against mature worms when given at 10, 5, and 2.5 mg/kg, respectively. Residual worms surviving drug treatment had less biomass than the controls. Praziquantel appears to be well tolerated by chickens, and treated birds showed no clinical reactions at any of the doses tested.

The ant, Pachycondyla sennaarensis (Mayr) as an intermediate host for the poultry cestode, Raillietina tetragona (Molin).

The role of several species of ants as intermediate hosts for poultry cestodes in the Sudan was investigated by a search for cysticercoids in specimens from poultry houses in various localities in the country. Pachycondyla sennaarensis, Messor galla and Acantholepis sp. were the only species collected from the areas surveyed. All these ants were examined for cysticercoids of poultry tapeworms but only P. sennaarensis was found to carry cysticercoids, all of which were identical to those of the poultry cestode, Raillietina tetragona. This tapeworm was recovered from all chicks fed the cysticercoids obtained from P. sennaarensis. R. tetragona cysticercoids were present in 63.3% of the P. sennaarensis sampled with 1-40 cysticercoids per ant, which is the heaviest recorded infestation of an ant species with these cysticeroids.

Raillietina cesticillus: variability of infections in experimentally infected chickens.

In experimental Raillietina cesticillus infections in chickens, the age of cysticercoids, the method by which the cysticercoids are administered and prior starvation of the host are factors that influence the development of infections.

Hymenolepis diminuta: immunogenicity of the strobilate worm.

Mice were immunized against challenge with Hymenolepis diminuta by feeding cysticercoids or by surgically implanting into the duodenum strobilate worms of different ages. Young worms stimulate stronger immunity than older ones, although the latter presents the host with a greater amount of strobilar tissue per unit time. An increase in the number of immunizing worms is associated with an increase in the level of protection. It is concluded that the development of functional immunity against H. diminuta in mice has both quantitative and qualitative antigenic requirements; it is influenced by worm age and is independent of worm mass.

Raillietina cesticillus: rejection by bursa-deficient chickens.

Chickens in which antibody-forming capacity was abrogated by bursectomy and irradiation developed protective immunity against Raillietina cesticillus as effective as controls which had specific antiworm antibodies in their sera and immunoglobulin positive cells in splenic and intestinal tissues. It is concluded that antibodies are not essential for the rejection of the tapeworm by chickens and may even retard rejection.