Lingual palpation for porcine cysticercosis: a rapid epidemiological tool for estimating prevalence and community risk in Africa

Abstract

ObjectiveTo assess the association between the prevalence of tongue cyst‐positive and antigen‐positive pigs across different settings in Africa, to evaluate whether examining pigs for cysts could be used as a rapid surveillance tool for identifying geographical areas with a higher probability of high transmission of cysticercosis.MethodsPublished data were collated from 26 study sites across Africa that reported the prevalence of porcine cysticercosis by both lingual and serological examinations. The study sites were located in 10 countries across Africa.ResultsSeroprevalence rates ranged from 4% to 41%. Despite the varied study sites, the relationship between the two variables was highly consistent and suggests identification of tongue cysts may be useful for cysticercosis surveillance. We found that all areas with more than 10% of pigs having cysts in their tongues had at least 30% seroprevalence (PPV of 100%), although this cut‐off is less reliable at predicting that an area is of low transmission (NPV of 84%).ConclusionAssessing the prevalence of tongue cyst‐positive pigs is a potential rapid epidemiological tool for identifying areas at high risk of cysticercosis, although further refinement and validation is required using standardised data sets.

Pig populations at risk of <em>Taenia solium</em> cysticercosis and subsequent financial losses in West and Central Africa

“…The expected prevalence of 30.05% calculated in our study is similar to that reported by Guyatt and Fèvre (2016). In a recent study, Braae et al (2015) used a Bayesian framework to estimate and map-informed district-level prevalence of porcine cysticercosis in Africa.…”

“…It is clear that this serological test has overestimated the real prevalence of porcine T. solium cysticercosis in the endemic areas of West and Central Africa, where T. hydatigena was present in studies carried out during the past two decades (Assana et al, 2013;Braae et al, 2015). In the studies conducted in Africa, the prevalence of meat and tongue cyst-positive pigs was lower than the prevalence of antigen-positive pigs (Guyatt and Fèvre, 2016). Subsequently, critical views have been raised to indicate that most positive pigs presented in the epidemiological studies in Africa in the past decades using Ag-ELISA are often not infected with any cysticercosis (Lightowlers et al, 2016).…”

“…Nevertheless, both tongue palpation and meat inspection methods have a specificity approaching 100% indicating that cysticerci identified by these methods classify the animal as true infected with T. solium cysticercosis (Dorny et al, 2004). Therefore, at the present time meat inspection and tongue palpation are the only practical and cost-effective techniques available for the diagnosis of porcine T. solium cysticercosis under field conditions (Guyatt and Fèvre, 2016).…”

Current Status of Prevalence, Possible Control and Risk Factors Associated with Porcine Cysticercosis from Endemic Countries in Africa

“…Because the prevalence of pigs with Tongue examination/palpation do relate to the prevalence of heavy infection. The data on this method were from [14] [26] [38] [39].…”

Possibilities of establishing a smallholder pig identification and traceability system in Kenya

“…The performance of these tests is variable; Dorny et al (2004) reported 21%, 22%, 35% and 86% as sensitivities for the tongue, meat inspection, antibody ELISA and antigen ELISA respectively. The tongue test is perhaps the easiest to conduct in live pigs and can be used by farmers, traders and veterinarians to identify infected pigs (Guyatt and Fevre 2016). The ability to detect cysts during meat inspection largely depends on the nature of the incisions and infection load (easy in heavily infested pigs).…”