We welcome the article by Loon et al.1 Earlier, we published our finding of the SARS coronavirus in specimens collected by the novel technique of conjunctiva upper respiratory tract irrigation (CURTI), but not in paired nose and throat swabs, very early in the course of the disease.2 In designing CURTI, we considered safety to medical personnel and, also, finding a method that samples all three portals of entry for upper respiratory viral pathogens—the eyes, nose, and mouth. Loon et al’s findings complement our study by showing that SARS coronavirus can indeed be found in tears.
While we agree with their conclusion that the ability to isolate the virus early in the course is important, we do not think that the eyes are important organs that propagate the virus, other than to ophthalmologists and to unwary close contacts. For instance, the eyes cannot generate infectious aerosol. Rather, we feel that the eyes are important portals of entry and have not been given sufficient attention—witness medical personnel in full personal protection gear and N95 masks but without watertight goggles, and sometimes without splashguards.
We also think that employing the services of ophthalmologists for the purpose of collecting tear specimens for the diagnosis of SARS is difficult to achieve in most medical environments. On the other hand, our method of CURTI is entirely self help, deployable in quarantine locations, and avoids unnecessary contact between an infectious source and susceptible individuals.
The finding of SARS CoV in tear raises several additional questions:
How does the virus end up in the tear? Was it the result of direct inoculation at the time of infection into permissive conjunctival epithelial cells, either by hand or aerosol, or was it the result of secretion from a lacrimal gland infected haematogenously? The lacrimal glands are not very different anatomically from the salivary glands. Yet saliva has been shown to be a poor specimen for the laboratory diagnosis of SARS.3
Was there any evidence of conjunctivitis, lacrimitis, or evidence of infection of the globe or nasolacrimal sac?
Is there any means or advantage in sampling the nasolacrimal sac, to which the tear drains, and could the nasolacrimal duct system be itself a hiding place for the SARS coronavirus during the incubation period?
References
- 1.Loon SC, Teoh SC, Oon LL, et al. The severe acute respiratory syndrome coronavirus in tears. Br J Ophthalmol 2004;88:861–3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Tong TR, Lam BH, Ng TK, et al. Conjunctiva-upper respiratory tract irrigation for early diagnosis of severe acute respiratory syndrome. J Clin Microbiol 2003;41:5352. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Drosten C, Chiu LL, Panning M, et al. Evaluation of advanced reverse transcription-PCR assays and an alternative PCR target region for detection of severe acute respiratory syndrome-associated coronavirus. J Clin Microbiol 2004;42:2043–7. [DOI] [PMC free article] [PubMed] [Google Scholar]