|Year : 2015 | Volume
| Issue : 4 | Page : 583-585
An ocular cysticercosis case: Caused by Asian genotype of Taenia solium
M Sharma1, N Beke2, S Khurana1, HS Bhatti1, R Sehgal1, N Malla1
1 Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Submission||17-Mar-2014|
|Date of Acceptance||09-Sep-2014|
|Date of Web Publication||16-Oct-2015|
Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
An ocular cysticercosis case of a 42-year-old male, who presented with anterior uveitis is being reported. Microscopical examination of the cyst revealed presence of only one hooklet suggestive of T. solium cysticercus. Mitochondrial DNA analysis confirmed it to be T. solium cysticercus of Asian genotype. This is the first report on molecular typing of cysticercus isolate from ocular cysticercosis patient in India. The study suggests that the molecular analysis of cox1 gene may be a useful diagnostic tool in cases where microscopic examination is not confirmatory.
Keywords: Cox 1 gene, ocular cysticercosis, Taenia solium
|How to cite this article:|
Sharma M, Beke N, Khurana S, Bhatti H S, Sehgal R, Malla N. An ocular cysticercosis case: Caused by Asian genotype of Taenia solium. Indian J Med Microbiol 2015;33:583-5
|How to cite this URL:|
Sharma M, Beke N, Khurana S, Bhatti H S, Sehgal R, Malla N. An ocular cysticercosis case: Caused by Asian genotype of Taenia solium. Indian J Med Microbiol [serial online] 2015 [cited 2019 Oct 15];33:583-5. Available from: http://www.ijmm.org/text.asp?2015/33/4/583/167319
| ~ Introduction|| |
Cysticercosis caused by the larval stage of cestode parasite T. solium is a serious public health problem world wide including China, India, Indonesia, Pakistan, Eastern Europe and Central America. Generally the cysts lodged in non-vital organs are of minor clinical significance, but their development in the central nervous system (CNS) and eye leading to neurocysticercosis (NCC) and ocular cysticercosis respectively, are causes of serious concern due to significant morbidity and mortality rates. The ocular manifestations can vary from asymptomatic in early stage of infection to destructive in later because cysticercus lesion gradually increases in size and can lead to blindness in 3–5 years. Ocular and orbital cysticercosis show various clinical symptoms such as proptosis, acquired ptosis, restriction of ocular motility, atypical optic neuritis, papilloedema, lid nodule, subretinal cyst and intra vitreous cyst., Initial medical treatment of ocular cysticercosis with antihelminthic drugs like praziquantel or albendazole is not known to be remedial and early surgical removal of the parasite is the treatment of choice. Reports from Japan  and Indonesia  have shown differentiation of Taenia species based on cox1 gene from NCC and ocular cysticercosis patient respectively. Within co x1, differential nucleotides served as diagnostic marker for human taenid cestodes or differentiation of two genotypes of Taenia. In the present study molecular characterization of T. solium cysticercus extracted from ocular cysticercosis patient was carried out based on the sequencing of cox1 gene.
| ~ Case Report|| |
A 42-year-old North Indian male presented with a 10 days history of redness in left eye, accompanied by mild degree of headache radiating from left periorbital region. There was no history of diminution of vision, seizures, vomiting and weakness. On ocular evaluation his best-corrected vision (Snellen's) was 6/6 in both eyes. Right eye evaluation on slit-lamp was within normal limits. Evaluation of the left eye on slit lamp revealed a pearly white coloured translucent cyst with a bright yellowish-white dot-like structure in its core. The cyst measured approximately 3 x 3 mm in its largest diameter, was freely mobile with undulating movements of its cyst wall, primarily confining itself to the inferior half of anterior chamber. The examination of anterior chamber was within range in other aspects, with no conjunctival/circumciliary congestion and no inflammatory cells/flare in anterior chamber. A dilated posterior segment evaluation was withheld, as there was risk of the mobile cyst migrating to access the posterior chamber, thus becoming irretrievable without considerable iatrogenic trauma to ocular structures in process. Ultrasound B-scan of the involved eye was within range and did not show presence of any cyst. A computed tomography (CT) scan of brain and orbit was also done to rule out the possibility of nerurocysticercosis and to support the diagnosis of ocular cysticercosis which was found to be negative. The cyst was surgically removed through a stab incision at limbus by viscoexpression technique and was subjected to parasitological evaluation. Post-operatively, patient maintained 6/6 vision (Snellen's) in the operated eye, and slit lamp evaluation showed anterior chamber with minimal inflammatory activity commensurate to surgical trauma, which was managed with topical steroids. Posterior segment evaluation through a dilated pupil was within range.
Microscopical and molecular DNA analysis
The examination of cyst under the microscope, revealed the presence of single hooklet suggestive of T. solium cysticerci. Further for definitive diagnosis, mitochondrial DNA analysis was done. The parasitic cyst was lysed in tissue lysis buffer and DNA extraction was done by using a QIAamp DNA mini kit. PCR amplification of cox1 gene was performed by using the primers and PCR conditions as described previously  with minor modifications. PCR was carried out in a 50 μl reaction mixture containing 2 μl DNA, 0.2 mM premixed solution of dNTP, 10 pmol of each primer, 1X PCR buffer, and 1 U of TaqDNA polymerase. Amplification program included an initial denaturation step of 95 ˚ for 5 min and 30 cycles each of denaturation (95 ˚ for 30 s), annealing (56 ˚ for 30 s), extension (72 ˚ for 90s) and final extension of 72 ˚ for 10 min. After agarose gel electrophoresis, PCR products were purified and sequenced.
The nucleotide sequence of the isolate (Accession number KC709810) was aligned with sequence of cox1 gene from known human Taenia cestodes [Figure 1]. Within cox1, differential nucleotides are dispersed over the entire length and served as diagnostic marker for human taenid cestodes or differentiation of two genotypes of Taenia. The nucleotide at 672 is for differentiation of three species of Taenia and nucleotides at positions 690 and 723 are useful to differentiate the two genotypes of T. solium. The nucleotide sequence of the isolate showed 100% homology with the sequence of T. solium cysticercus isolated from pigs in India (Accession No KC709806). In phylogenetic analysis the isolate was found to be clustered with other Asian genotype of T. solium [Figure 2].
|Figure 1: Representative Multiple alignments of partial cox1 mitochindrial gene sequences from human taeniid cestodes. The nucleotide sequence of the case described in this study, accession number KC709810 (shown on the top) was aligned with sequence of the Asian (from India and China) genotype of T. solium (AB066489 and AB066485), the American (from Brazil) and African (Tanzania) genotype of T. solium (AB066492 and AB066493), T. saginata (AB066495) and T. asiatica (AB066494)|
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|Figure 2: Dendrogram constructed with the cox1 mitochondrial gene sequence obtained from human taeniid cestodes. The sequences were compared with sequence of reference genotypes|
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| ~ Discussion|| |
T. solium cysticeri can settle in any part of eye but the cyst is most commonly present in subretinal space (35%) followed by conjunctiva (22%), other vitreous locations (22%), and rarely (1%) in the orbit. In the western literature, vitreous and sub retinal space have been reported as the commonest site but in India, sub conjunctiva has been the favourable site for the parasite.,, There are few reports describing the anterior uveitis due to cysticercus cyst in the anterior chamber., In the present case, patient presented with severe uveitis due to cysticercal cyst in the anterior chamber of eye. Microscopical examination of the cyst revealed only one hooklet suggestive of T. solium cysticercus. Molecular analysis of mitochondrial cox1 gene confirmed it a T. solium cysticercus of Asian genotype.
This is the first report on molecular typing of cysticercus isolate from ocular cysticercosis patient in India. The study suggests that the molecular analysis of cox1 gene may be a useful confirmatory diagnostic tool and for molecular identification of taeniid cestodes.
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[Figure 1], [Figure 2]