The use of an enzyme-linked immunosorbent assay for tropical theileriosis research in Morocco

An enzyme-linked immunosorbent assay (ELISA) using sonicated purified Theileria annulata piroplasms was compared with an indirect immunofluorescent antibody test (IFAT) during a vaccination trial in cattle to test different doses and passage numbers of an attenuated T. annulata-infected lymphoblastoid cell-line, and also with Giemsa-stained blood smears during an epidemiological field study of tropical theileriosis in Morocco. The sensitivities of both the ELISA (0.56) and the IFAT using T. annulata piroplasm antigen (0.56) were lower than the IFAT using schizont antigen (0.94) for detecting serum antibodies from 18 cattle immunised 38 days previously with cell-line. The ELISA was, however, the most sensitive test after 180 days (0.50 compared with 0.06 for the piroplasm IFAT and 0.39 for the schizont IFAT), and each test detected antibodies in all sera after challenge with live T. annulata sporozoites. There were minor differences in the ability of blood smear examinations and the ELISA to detect infected and uninfected cattle in the field study at the start and end of the disease season. Initially, the sensitivity and specificity of blood smears were both 0.96 and for the ELISA were 0.83 and 0.86, whereas at the end of the season sensitivity and specificity of blood smears were 0.96 and 0.86 and for the ELISA were 0.95 and 0.94. The specificity of the ELISA was affected by the presence of calves with colostral antibodies, and if these were disregarded the specificities before and after the season were 0.94 and 1.00.     

Observations on the epizootiology of gasterophilus intestinalis and G. nasalis in horses in morocco

Ninety four horses from the Settat region of Morocco were examined for Gasterophilus intestinalis and G. nasalis larvae. All the horses were infected with G. intestinalis and 89 with G. nasalis; the mean larval burdens were 219 and 153, respectively. Third instar larvae of both species were present throughout the year. Second instar larvae of G. intestinalis were absent in April and May and those of G. nasalis in April only. More than 50% of horses had total burdens of more than 300 larvae and 4% harboured more than 1000 larvae. Young horses had higher infections than older animals. The period of adult activity of G. intestinalis is from April to October, with a maximum in summer. Second instar larvae of G. intestinalis are present in peak numbers from July to January and the third instars are voided in the faeces mainly in spring and summer.Infection with G. nasalis starts sooner than that with G. intestinalis. Second instar larvae are present from May to December in peak numbers. During January to March, many second instars of G. nasalis were found trapped in nodules.     

Epidemiological observations on Gasterophilus intestinalis and G. nasalis in donkeys from Morocco.

During a 24 month period, 198 donkeys were examined for Gasterophilus intestinalis and Gasterophilus nasalis larvae. Gasterophilus intestinalis was found in 97.5% and G. nasalis in 95.5% of donkeys. The third instars (L3) of both species occurred during all months of the year and so did the second instars (L2), except in April (G. nasalis) and May (G. intestinalis). Over 75% of the animals had up to 200 larvae and 1.5% had over 600 larvae. The maximum number of both L2 and L3 larvae found in any animal was 418 G. intestinalis, 433 G. nasalis and 715 of both species combined. The seasonal variation in the numbers and development status of larvae indicated that the period of greatest activity of adult flies of G. intestinalis was from August/September to November, and that of G. nasalis from May to September. Consequently, the L2 larvae in the stomachs were in peak numbers between November and January for G. intestinalis and between July and September for G. nasalis. The L3 larvae of G. intestinalis had peak numbers between December and July, and those of G. nasalis between October and March. During January-March, most of the L2 larvae of G. nasalis were trapped in polypous nodules near the pyloric end of the stomach. It is concluded that the high-risk period for infection is during late spring and autumn, leading to the heavy larval burden of Gasterophilus in the stomach of donkeys during winter.     

Effect of infection by Babesia spp. on the development and survival of free-living stages of Boophilus annulatus

Oviposition, egg hatching and survival of newly-hatched larvae of Boophilus annulatus were studied in relation to infection by Babesia species and different temperature regimens. Infection of female ticks by Babesia bigemina or B. bovis had no effect on the time elapsed between engorgement and oviposition. The duration of oviposition was shorter in infected females incubated at 25 degrees C or 35 degrees C and infected females laid fewer eggs than the controls. No larvae hatched at 16 degrees C. B. bigemina-infected eggs hatched more quickly than uninfected eggs at 35 degrees C. The hatching percentage of B. bigemina-infected eggs was reduced by 50% at an incubation temperature of 25 degrees C and by 75% at 35 degrees C. At 16 degrees C there was no difference in the duration of survival of infected and non-infected larvae but at 25 degrees C and 35 degrees C the mean survival period of infected larvae was significantly lower than those of controls.