New Test May Help Prevent Blindness in Developing World

FRIDAY, May 12 (HealthDay News) -- A new test for trachoma, the leading infectious cause of blindness in the world, is more accurate than existing techniques and could spare millions of people the fate of permanent vision loss.

"This is a very exciting development," said Dr. Jacob Kumaresan, president of the International Trachoma Initiative. "The whole issue of trachoma has been neglected for many years. This shows that the current tools we''re using can be improved, although more work needs to be done to make sure it''s applicable in the field."

"It''s an important advance, because trachoma is one of the leading causes of blindness in the world, especially in the Third World," added Dr. Robert Cykiert, clinical associate professor of ophthalmology at New York University School of Medicine in New York City.

The study appears in the May 13 issue of the Lancet.

According to the World Health Organization, as of 1995, nearly six million people worldwide are already blind because of trachoma, and 150 million people have the infection and need treatment, most of them in developing countries.

Trachoma is caused by the Chlamydia trachomatis bacterium, which can infect the eyes and genitals. While the disease is most common in children, over several decades of re-infection, the continuing inflammation can force the eyelids to invert. This forces the lashes to abrade the cornea and produces blinding scars.

The bacteria are spread by means of hand-to-eye contact and by the omnipresent flies that feed on cow dung and human waste in poor villages. Proper sanitation and hygiene are critical factors in controlling the infection, say experts.

In African and Asia, unclean conditions keep the bacteria rampant. As a result, up to 25 percent of older people infected with the microbe eventually will go blind.

One of the major problems so far in fighting the scourge has been the lack of a good diagnostic test.

"Up to now, it hasn''t been easy to determine if somebody has it," Cykiert explained. "The findings are suggestive, but you don''t always know for sure, so you''re missing some cases or maybe misdiagnosing some."

In this study, the authors compared a new point-of-care test for the infection with the current standard, which looks for clinical signs of trachomatous inflammation (TF). The current standard, however, does not match especially well with presence of actual infection.

The study involved 664 children, aged 1 to 9, in remote villages in the East African country of Tanzania.

The new test had a higher specificity (meaning the proportion of people without infection who produced a negative result on the test) as well as a higher sensitivity (the proportion of infected people who came back with a positive result). Specificity of the new test was 99.4 percent compared to 80.2 percent for the old screen. The test''s sensitivity was 83.6 percent compared with 64.1 percent for the older test.

"The test is very simple to perform, very rapid and does not require trained personnel or any equipment," said study senior author Helen Lee, of the University of Cambridge, in the United Kingdom. "We have shown that it works very well in the Masai villages in Tanzania, with no electricity or running water. Even the cell phone did not work. We used tables and chairs as makeshift lab benches, and it took less than an hour to train the local healthcare personnel to do the test, and we were able to test hundreds of children easily and effectively," she said.

"Our study shows that the new point-of-care test predicts the presence of Chlamydia trachomatis infection much better than clinical signs and thereby allows more accurate and targeted antibiotic treatment, which will save precious resources in these very poor communities," Lee continued.

The new test does need further study, however.

"They''ve shown that, in clinical settings, it does make a significant difference," Kumaresan said. "The next step is to go and do it in field settings. These studies are very, very crucial."

"Once that is done and the test can be applicable for mass communities, I think costs will go down," he continued.

And lower costs mean more people can be screened and treated.

"We have received a grant from the Wellcome Trust to test 6,000 children in Tanzania, Gambia and Ethiopia," Lee said. "I am optimistic that the excellent test performance will be confirmed in the larger population from different countries. The new test will enable programme managers to better target antibiotic treatment to those communities that really need it," she said.

More information

To learn more about trachoma, visit the International Trachoma Initiative.

SOURCES: Robert Cykiert, M.D., ophthalmologist, New York University Medical Center, and clinical associate professor, ophthalmology, New York University School of Medicine, New York City; Helen H Lee, Ph.D., Department of Haematology, University of Cambridge, Cambridge, U.K; Jacob Kumaresan, M.D., president, International Trachoma Initiative, New York City; May 13, 2006, Lancet

Last Updated: May 12, 2006