Use of the nested polymerase chain reaction for detection of Toxoplasma gondii in slaughterhouse workers in Thika District, Kenya

Abstract

Background. The widely used methods of diagnosis of Toxoplasma gondii are serological. Current reports indicate a high seroprevalence of T. gondii in humans in Kenya. There is a need for more sensitive diagnostic tests, especially when the specific antibody titres are below detectable threshold levels. Use of the polymerase chain reaction (PCR) targeting the repetitive 529 base pair loci has been reported to be sensitive and specific. Objective. To detect T. gondii in a high-risk group of public health workers in Thika District, Kenya. Methods. In total, 87 human blood samples were collected from male slaughterhouse workers between 1 March 2013 and 25 June 2013. The DNA extracted was amplified by the nested PCR. Results. T. gondii was detected in 39.1% (34/87) of the workers. In the cow-sheep-goat slaughterhouses the prevalence ranged between 20% and 60%, while all the chicken slaughterhouse workers (6/6, 100%) tested positive. The difference in T. gondii positivity between the workers in the chicken slaughterhouse and those in the cattle-sheep-goat slaughterhouses was statistically significant (p=0.003). Conclusion. This study shows the presence of T. gondii in an asymptomatic high-risk group in Thika District, indicating the need for enhancement of public health awareness.

Detection of NaturalToxoplasma gondiiInfection in Chicken in Thika Region of Kenya Using Nested Polymerase Chain Reaction

“…The study was undertaken in an area which was previously shown to have high prevalence of T. gondii among the slaughterhouse workers [9]. The high (79%) prevalence of T. gondii in all the areas showed that the free-range chickens are a major reservoir for T. gondii parasites.…”

“…In this study, detection of T. gondii DNA in brain samples was done by nPCR, based on the multilocus 529 bp repeat element which gives increased diagnostic sensitivity and accuracy compared to that which can be obtained when targeting the B1 gene that exists in 35 copies/genome [13, 28]. However, the sensitivity of PCR may be limited by the random distribution of the parasite and varying parasite densities in affected tissue [9, 29]. The use of PCR may also be limited by the need for thermocycler, expensive reagents, and skilled manpower.…”

“…In Thika region, farmers indicated that they disposed cat faeces in areas accessible by free-range chickens [7]. In the same region, a higher prevalence (39%) of toxoplasmosis was observed in chicken slaughterhouse workers compared to workers in other types of slaughterhouses [9] and this shows that chicken meat and offal could be a source of the Toxoplasma- derived tissue cysts for man.…”

Development of Neurological Mouse Model for Toxoplasmosis Using Toxoplasma gondii Isolated from Chicken in Kenya

“…D3025) and amplification of the 529 bp repeat units was carried out by nested PCR as previously described [14, 15]. Secondary amplification products were electrophoresed on 1.5% agarose gel stained with ethidium bromide and visualized under ultraviolet (UV) light.…”

A Review on the Present Advances on Studies of Toxoplasmosis in Eastern Africa

“…In another study carried out by Njuguna et al [ 49 ] to establish the prevalence of gastrointestinal (GIT) parasites in fecal samples of 103 cats kept by households in Thika region, Toxoplasma gondii was detected in 7.8% (95% CI: 4.5–11.1%) of the samples collected. Another recent study in Thika region showed that up to 39% of the slaughterhouse workers were infected with T. gondii as detected using nPCR [ 50 ].…”