Cysticercosisis a parasitic zoonoses caused by the metacestodes of Taenia solium, a two-host zoonotic cestode.
It is of much economicand public health importance causing morbidity and mortality in many developingcountries of South-East Asia, Africa and Latin America (Giri & Parija, 2012;Rajshekhar et al, 2003; Ito et al, 2004) where pigs are raised forconsumption under traditional husbandry practices. It has been designated as a”biological marker” of the social and economic development of a community(Carpio et al. 1998).Cysticerci(larval cysts) can develop in any organ in the body. Cystercerci in the centralnervous system (brain or spinal cord) causes the most serious form of infectionknown as neurocysticercosis (NCC).
It is considered to be the most commonparasitic infection of the human nervous system and the most frequentpreventable cause of epilepsy in the developing world (Román et al.,2000; Del Brutto et al., 2001).
The clinical manifestations of NCC varywith seizures being the most common presentation of symptomatic NCC, affectingfrom 69% to 96% of cases (Del Brutto etal.,1992; Bern et al., 1999; Carpio and Hauser, 2002; Garcia etal, 2005) which is the main cause of late onset epilepsy in endemic areas(Flisser et al., 1998).
In additionto seizures and epilepsy, NCC can manifest with severe chronic headaches,blindness, hydrocephalus, meningitis, symptoms due to space-occupying CNSlesions, dementia and even death (Townes et al., 2004; Sorvillo et al., 2007). People who neither raisepigs nor consume pork are also at risk of cysticercosis if they ingest T.solium eggs after coming into direct or indirect contact with tapewormcarriers. Vegetarians in India have been found to be at high risk of infectionfrom tapeworm infected food preparers (Rajshekar et al.
, 2003).Thedisease is prevalent in virtually all states of the country, although theprevalence rates vary significantly between different states (Rajshekhar andChandy, 2000). Thesingle cyst infection (47.7% – 53.4%), is the most common in Indiansubcontinent (Prasad et al., 2008).
In most cases, NCC diagnosis is based on neuroimaging studies i.e.Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). MRI isconsidered the best neuro-imaging tool for the detection of degenerating andinnocuous (viable) cysticerci, while CT is the best for calcified lesions(Garcia et al.
, 2003). Thesetechniques are also not accessible for the poor people of endemic area becauseof very high cost. Therefore the development of immunodiagnostic tests thatdetects specific antibodies in the serum or CSF is the need of urgency (Ito et al., 2003). ELISAhas been used widely by for the detection of antibodies in the serum withvariable sensitivities and specificity in diagnosis of NCC in definitive cases(Shukla et al.
, 2008). Western blotwith lentil lectin purified glycoprotein (LLGPs) or the enzyme-linkedimmunoelectro transfer blot (EITB) has been the “gold standard” serodiagnosticassay and was originally reported to have sensitivity of 98% and specificity of100% (Tsang et al., 1989).Immunodiagnostic techniques depend largely on a good, potent and purifiedantigen prepared from the Taenia soliummetacestodes like low molecular mass antigens (Atluri et al., 2009), excretory/secretory, somatic antigens (Sahu et al., 2009), crude soluble extract(Atluri et al.
, 2009), total salineextract (Oliveira et al., 2007),vesicular fluid (Arruda et al.,2005), membrane and scolex extracts (Arruda etal., 2005). For many parasitic diseases like malaria, amoebiasis etc.excretory secretory (ES) antigens have been found to perform much better thanthe crude somatic antigens. There are a few studies on use of ES antigens fordeveloping antibody ELISA. An advantage of using ES antigens instead of somaticantigens for detection of antibodies against T.
solium cysticerci isthat it is possible to determine whether the parasite larva is living, dead ordegenerated (Molinari et al., 2002).Neurocysticercosisremains a serious neglected problem in marginalized communities in many areasof India mainly due to poverty, ignorance, lack of suitable diagnostic &management capacity and inappropriate prevention and control strategies. Thecosts for performing neuroimaging techniques are very high, mainly for thepublic health system. For routine laboratory tests, the best choice for a NCCscreening could be the use of immunoassays that combines accuracy, sensitivity,and reasonability (Ito, 2002? Flisser etal., 2006). The present study utilizes three different antigenicpreparations (Sccolex antigen, excretory secretory antigen and membrane bodyantigen) from Cysticercus cellulosaein the serodiagnosis of NCC in epileptic patients by indiect IgG-ELISA andEITB. Simultaneously, for the first time, an attempt has been made for thedetection of NCC by PCR from blood samples of the same patients targeting LSUrRNA gene of Taenia solium.
Materials and methodsCollection of samplesThepresent study was conducted in the Department of Veterinary Public Health,Nagpur Veterinary College, Nagpur, Maharashtra, India. A total of 26 epilepticpatients who visited Get Well Hospital and Research Institute, Nagpur fortreatment during the period from January 2016 to July 2016, suspected to be NCCclinically and/or radiologically with history of seizures, within the age rangeof 6-53 years were included in the study after obtaining consent from them.Blood and sera samples were collected along with their CT scan/ MRI findings(as observed by the neurologist). Parallel 10 samples from healthy volunteershaving no neurological symptoms were included in the study as negative controlsin order to calculate the cut-off O.D. value.
The sera were subjected to screeningof anti-cysticercus antibodies by in-house developed ELISA employing threedifferent antigens prepared from Cysticercuscellulosae followed by determination of immunodominant proteins by EITBemploying the same antigens. The blood samples were subjected to DNA isolationfor molecular identification.