Acquisition and transmission of Theileria parva by vector tick, Rhipicephalus appendiculatus

Abstract

In order to investigate the transmission dynamics of Theileria parva (T. parva) by the brown ear tick, Rhipicephalus appendiculatus (R. appendiculatus), under experimental conditions, detection of T. parva in ticks and cattle was performed by a quantitative real-time PCR assay. A calf inoculated with a T. parva mixture became PCR-positive for T. parva infection on day 8 post-inoculation, and subsequently, nymphal ticks were introduced and maintained to feed on the infected calf for 6 days. Engorged nymphs were collected daily and allowed to molt into adults, and overall, 70.8% (121/171) of the adult ticks acquired the T. parva infection. Furthermore, the T. parva infection rate in ticks under field conditions was monitored by real-time PCR in R. appendiculatus ticks collected from a traditionally-managed pastoral land of Zambia, on which Sanga breed cattle are traditionally reared and the area has endemic East Coast fever (ECF).A total of 70 cattle were randomly selected in the same area and 67 (95.7%) were found to be serologically positive for R. appendiculatus tick antigen (RIM36). Twenty-nine (43.3%) of the 67 serologically positive cattle were real-time PCR-positive for T. parva, although no piroplasms could be detected in the blood smears. Unexpectedly, out of 614 R. appendiculatus nymphal and adult ticks collected by flagging vegetation, 4.1% were positive for T. parva DNA. However, since the rate of transmission of T. parva from infected cattle to ticks and vice versa and the serological evidence of exposure to R. appendiculatus ticks in naturally-exposed cattle were relatively high, it would be wise in such a case to consider vector control as well as vaccination against ECF as control measures.3

Abundance and distribution of Ixodid tick species infesting cattle reared under traditional farming systems in Tanzania

“…Of the tick species that were identified in this study, R. appendiculatus was the most abundant in Mara region, followed by A. variegatum. R. appendiculatus is a vector of Theileria parva which causes a fatal disease known as East Coast fever (ECF) in cattle (Mulumba et al, 2001;Konnai et al, 2006). East Coast fever has a considerable epidemiological and economic impact in the affected areas.…”

Quantitative Analysis of Cytokine mRNA Expression and Protozoan DNA Load in Theileria parva-Infected Cattle

“…The T. parva-infected ticks were used for experimental infection of cattle. The infection rate of adult R. appendiculatus ticks was determined by T. parva-specific nested PCR described previously [16].…”

“…Real-time quantitative-PCR for the detection of T. parva p104 gene: Real-time PCR amplification of the p104 gene was performed in a Light Cycler TM (Roche Diagnostics, Mannheim, Germany) as described previously [16]. A three microliter aliquot containing 100 ng of DNA derived from 0.5 ml of bovine whole blood was added to a 17 µl reaction mixture containing SYBR Premix Ex Taq TM II (TAKARA) and each of the oligonucleotide primers at the final concentration of 0.2 µM.…”

Attachment Duration Required forRhipicephalus appendiculatusto TransmitTheileria parvato the Host

“…In an experimental model, both R. appendiculatus and Boophilus microplus acquired and transmitted T. parva and Babesia equi after feeding on experimentally infected animals with low-level parasitaemia (Konnai et al 2006, Ueti et al 2005. In case of T. parva infection, ticks (70.8%) that acquired T. parva from an infected cow with low-level parasitemia, successfully transmitted the parasite to naive cattle (Konnai et al 2006).…”

“…In an experimental model, both R. appendiculatus and Boophilus microplus acquired and transmitted T. parva and Babesia equi after feeding on experimentally infected animals with low-level parasitaemia (Konnai et al 2006, Ueti et al 2005. In case of T. parva infection, ticks (70.8%) that acquired T. parva from an infected cow with low-level parasitemia, successfully transmitted the parasite to naive cattle (Konnai et al 2006). Transmission rate of T. parva from infected cattle to ticks and vice versa, as well as serologic evidence (RIM36) of natural exposure to R. appendiculatus ticks (Bishop et al 2002) have been shown to be relatively high (Konnai et al 2006).…”