Theileria parva

Pienaar, Ronel, Troskie, P. Christo, Josemans, Antoinette I., Potgieter, Fred T., Maboko, Boitumelo B., Latif, Abdalla A. & Mans, Ben J., 2020, Investigations into the carrier-state of Theileria sp. (buffalo) in cattle, International Journal for Parasitology: Parasites and Wildlife 11, pp. 136-142 : 138

3.3. Monitoring T. parva and T. sp. (bu ff alo) positive cattle

Six cattle (B24, B53, B120, B121, B163, B164) positive for T. parva were moved from Bedrog to ARC-OVR for long term monitoring. One animal (B24) became negative shortly after arrival and did not test positive over a 24-month period. One animal (B164) with intact spleen that showed an increase in parasitemia died of natural causes ~ one year into the monitoring period. Two animals (B53 and B120) were splenectomized a week after their CP values reached the PCR cutoff value (37 cycles) on 05 August 2014 (8 months after the outbreak). The animals showed intermitted CP values that fluctuated below the PCR cutoff value before steadily decreasing (increased parasitemia) ~6 months after splenectomy. For the non-splenectomized animals (B121 and B163) the CP values fluctuated around the detection limit ( Fig. 2 ).

Four cattle (B21, B79, B123, B631) positive for T. sp. (buffalo) were moved from Bedrog to ARC-OVR for long term monitoring. All animals became PCR negative within 5 months, except for B79 for which CP values fluctuated around the cut-off for ~2 years of testing. B123 and B631 remained negative for the duration of the testing. One animal (B21) was splenectomized a week after its CP value reached the cutoff, after which it tested negative for ~6 months before it became PCR positive again ( Fig. 2 ). This animal remained positive to date with a trend of detectable but fluctuating parasitemia ( Fig. 2 ).

3.4. Infection of an African bu ff alo and a bovine using a macroschizont-infected lymphoblastoid cell culture of T. sp. (bu ff alo)

Neither the bovine nor the African buffalo showed adverse signs after infection using the cell culture material. On day 35 post infection both animals were monitored for the appearance of piroplasms using Giemsa stained smears and for the presence of T. sp. (buffalo) using real-time PCR. Buffalo 114 showed the presence of piroplasms and schizonts and tested positive for T. sp. (buffalo) using real-time PCR with a CP value of 33.2. The bovine did not show the presence of any schizonts or piroplasms and tested negative using real-time PCR.

Figures

Fig. 2. Monitoring of Theileria parva and Theileria sp. (buffalo) positive animals over a period of 24 months. The gray shaded areas indicate CP values below the cut- off of the PCR assays. Stars indicate animals that were splenectomized and the arrow indicate the date of splenectomy. The cross indicates an animal that died of natural causes.