High levels of congenital transmission of Toxoplasma gondii in a commercial sheep flock

Outbreak of ovine congenital toxoplasmosis in Iran, confirmed by different diagnostic methods

“…There are a lot of unclear aspects of its congenital importance. According to the results of the recent researches in the UK, Toxoplasma vertical transmission can occur more frequently than what was previously thought (Duncanson et al 2001;Morely et al 2005Morely et al , 2007Hide et al 2009;Innes et al 2009;Dubey 2009), but Edwards and Dubey (2013) reported that this problem is resolved in the involved flock after one year or two years. If this kind of abortion takes place, it needs to be dealt with either by taking prophylactic measures or culling infected sheep from the flock which is more economical.…”

“…It was first described by Hartley et al (1954) which even today is known as one of the major causes of sheep abortion world wide (Buxton 1991). Another characteristic of vertical transmission of T. gondii is that this kind of transmission can occur more frequently than what was previously thought (Duncanson et al 2001;Morely et al 2005Morely et al , 2007Hide et al 2009;Innes et al 2009;Dubey 2009). …”

High frequency detection ofToxoplasma gondiiDNA in human neonatal tissue from Libya

“…Further DNA purification was carried out using phenol/ chloroform/isoamyl alcohol as previously described. 22 Purified DNA was tested by PCR using primers to the mammalian tubulin gene to ensure the suitability of the DNA for PCR as previously described. 22 Appropriate protocols were used at each stage of the DNA purification and any subsequent PCR amplifications to prevent cross-contamination as described previously.…”

“…[16][17][18] However, the frequency of this mode of transmission in natural populations of animals, or humans, is less clear. PCR based studies on the transmission of T. gondii in several mammalian species, e.g., mice, woodmice 17,[19][20][21] and sheep [22][23][24][25] have suggested that congenital transmission may be occurring at a higher frequency than previously thought. Although higher frequencies of congenital transmission are reported in these studies, in many cases there seems to be no measurable disease effect on the neonates in these species.…”

“…1 However, some studies have suggested that more sensitive techniques, such as PCR or parasite detection by bioassay, are capable of detecting parasites in seronegative individuals (e.g., in rodents, 29,30 pigs 31 and humans 32 ). In the PCR based studies on sheep, 22,23 the measurement of congenital transmission was conducted utilising umbilical cord tissue as a proxy for neonatal tissue. In those studies, comparison of PCR detection of Toxoplasma DNA in umbilical cord tissue with internal tissues (brain) from infected and uninfected aborted lambs showed very strong agreement.…”