The current epidemiological status of bovine theileriosis in eastern Zambia

Abstract

SummaryResults of a longitudinal study conducted in the eastern province of Zambia from 1994 to 1997 indicate that it is doubtful whether a state of endemic stability of East Coast fever (ECF) can be reached in the near future. Even in endemic areas, the mortality of Theileria parva infections is still estimated above 50%. The main factors limiting progress towards endemic stability are high innate susceptibility of the Zebu cattle, the virulence of the parasite and the climate. The unimodal rainfall pattern results in restricted activity of Rhipicephalus appendiculatus instars and year-to-year variation in rainfall causes fluctuations in tick phenology and T. parva transmission. Adult tick activity invariably peaks during the rains and is associated with the highest ECF incidence. Nymphal transmission of T. parva to cattle appears to be less important. Second periods of activity of both adult and nymphal instars are pronounced only when the climate is suitable. These second waves of tick activity ensure a more continuous and efficient transmission of T. parva and also play a key role in the dynamics of prolonged outbreaks in epidemic areas. ECF control methods may have an important influence on ECF epidemiology. Immunizations as well as chemotherapy of clinical cases create a reservoir of virulent parasites in susceptible cattle, resulting in artificial endemic stability.

Further evidence for geographic differentiation in R. appendiculatus (Acari: Ixodidae) from Eastern and Southern provinces of Zambia

“…In addition, Tempia (1997) reported higher infection rates for Theileria parva (Katete), strain from the Eastern province in adults of R. appendiculatus from the Southern province than Haplotype location: Haplotype 1 = Southern province and Nyimba district; Haplotypes 2-5 = Eastern province plateau districts 1 C R. appendiculatus from the Eastern province plateau. These diVerences manifest themselves in signiWcant diVerences in the epidemiology of ECF between the Southern and Eastern provinces (Speybroeck 2004;Billiouw 2005).…”

“…The reported diVerence in the epidemiology of ECF in Eastern and Southern Zambia (Billiouw 2005;Speybroeck et al 2004) is therefore due in a large part to the diVerence in the vector ticks. The spread and establishment of either group of ticks into another group's area of endemicity has a potential to change the epidemiology of ECF for that area.…”

“…IdentiWcation of ticks and DNA extraction DNA extraction was based on the method of Boom et al (1990Boom et al ( , 1999 as described in Mtambo et al (2006). All the 60 specimens of R. appendiculatus used in this study were identiWed by the use of a PCR-RFLP based on the digestion of the ITS2 with Bau I (JM unpublished).…”

Epidemiological analysis of tick-borne diseases in Zambia

“…Moreover, it has been more than twenty years since any comprehensive studies on the epidemiology of babesiosis and anaplasmosis in Zambia have been conducted (Jongejan et al, 1988) and there is no available data on heartwater in cattle. Although there have been a number of studies on ECF (Berkvens, 1991;Billiouw et al, 1999;Fandamu et al, 2005), there is no information on the prevalence of T. parva in most parts of the country. This paucity of epidemiological information is a significant impediment to the development of cost-effective control strategies.…”

Genetic Variation in 12S and 16S Mitochondrial rDNA Genes of Four Geographically Isolated Populations of Gulf Coast Ticks (Acari: Ixodidae)

“…Using the mitochondrial COI gene, Mtambo et al (2007) discovered signiÞcant genetic variation between Rhipicephalus appendiculatus populations in the eastern and southern provinces of Zambia where this vector transmits Theileria parva (Katete), the causative agent for East Coast fever in cattle. In addition, Tempia (1997) found higher infection rates for T. parva in R. appendiculatus adults in the Eastern province than the Southern province, which lends support to the significant regional differences in the epidemiology of East Coast fever (Speybroeck et al 2004, Billiouw 2005. Additional population genetic studies have been conducted on disease vectors, such as Aedes aegypti, Ae.…”