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This study was conducted to determine tick burden and immunological parameters of resistance to East
Coast fever (ECF) in Tarime and Sukuma cattle. Tick load, packed cell volume (PCV), Theileria parva (T.
parva) specific antibody percent positivity (PP), and prevalence of T. parva parasites were studied in relation
to dipping regime, strains, and season. A total of 50 experimental cattle were included in this study. Tick load
was determined by whole body counts, antibody percent positivity was determined by the polymorphic
immunodominant molecule (PIM)-based T. parva enzyme-linked immunosorbent assay (ELISA), and
prevalence of T. parva parasites was detected by a nested polymerase chain reaction (PCR) based on the
p104 gene. Dipping frequency on tick burden showed no statistically significant differences when cattle of
either strain were dipped either once every 2 or 3 weeks in the dry and wet seasons. However, Tarime cattle
had higher (p<0.05) tick count than Sukuma cattle and non dipped groups maintained high tick infestation
throughout the experimental period. The PCV values were within the physiological range, although this
parameter was lower in Tarime cattle (p<0.05). All cattle regardless of strain were seropositive, although
Tarime cattle maintained higher PP compared to Sukuma by 15%. Conversely, the prevalence of T. parva
parasites was lower in Tarime (38%) compared to Sukuma cattle (38.5%), but the difference was not
significant (p>0.05). During the study period, 20% (5/25) of Sukuma cattle contracted ECF, but none of the
Tarime cattle showed clinical signs for the disease. The differences between the two strains shown in terms
of PP and T. parva parasite prevalence may indicate the ability of individual cattle to resist tick infestation
and ECF infection under natural challenge. Higher antibody levels but lower parasite prevalence attained by
Tarime cattle, suggests inherent ability of Tarime cattle to resist clinical development of ECF infection, but to
remain as T. parva carriers. |
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