Molecular Diagnosis of Human Taenia martis Eye Infection

Abstract

Taenia martis, a tapeworm harbored in the intestine of mustelids, is a rarely encountered zoonotic cysticercosis pathogen. The larval stage closely resembles the Taenia solium cysticercus, but the natural host and thus the epidemiology of the disease is different. We here report a human eye infection diagnosed molecularly in a previously healthy female German patient. The case represents the third human infection described worldwide; the two previous cases were also European, involving eye and brain.

Figure 1.

Histological section through the cystic tapeworm larva recovered from the patient's eye. The parasite's spongy tissue is surrounded by a ruffled tegument. Periodic acid–Schiff stain, original magnification ×10.

Figure 2.

Phylogram of the patient's Taenia martis isolate and sequences from GenBank (bootstrap consensus tree). The asterisks denote T. martis sequences from human infections. A multiple sequence alignment using parasite cox sequences was generated using MUSCLE. Poorly aligned and divergent positions were removed using Gblocks with the parameter settings –t = d, -b1 = 6, -b2 = 6, -b3 = 8, -b4 = 5, -b5 = h. The final alignment comprised 396 of the original 1,620 positions from 10 sequences. MEGA 6 was used for subsequent substitution model estimation as well as phylogenetic tree reconstruction. The evolutionary history was inferred by using the maximum likelihood method based on the Hasegawa–Kishino–Yano model. The tree inferred from 500 replicates is taken to represent the evolutionary history of the taxa analyzed. Branches corresponding to partitions reproduced in less than 50% bootstrap replicates are collapsed. Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the maximum composite likelihood approach, and then selecting the topology with superior log likelihood value. The analysis involved 10 nucleotide sequences. Codon positions included were 1st + 2nd + 3rd + noncoding.

Figure 3.

Left eye after surgical removal of subretinal Taenia martis cysticercus. (A) Close-up view showing conjunctival injections 4 weeks after vitrectomy. (B) Fundoscopy displaying retinal scar 8 weeks after fluid-gas-exchange and endolaser treatment. (C) Fundoscopy showing reattached macular area 8 weeks after vitrectomy.