The estimates for North America alone are between 5 and 8 million new infections each year, with an estimated rate of asymptomatic cases as high as 50%.

The degree to which malabsorption occurs in symptomatic and asymptomatic cases is highly varied.

Further, in asymptomatic cases, sudden death is considered one of the most feared complications associated with the disease in select pediatric population.

Mr. Jubeir said the thousands of doctors Saudi Arabia hires in hajj season to screen pilgrims could not detect asymptomatic cases.

They strongly suspected that the difference due to prostate cancer was a result of greater detection of asymptomatic cases in the U.S.

On April 14, Chinese officials also reported the first asymptomatic case in Beijing.

Other rather conservative medical treatments for stable and asymptomatic cases include low sodium diet, diuretics, digoxin, calcium blockers and avoiding very strenuous activity.

The largest number of asymptomatic cases was confirmed in 2006 among Korean workers who had assisted in massive culls of H5N1-infected poultry.

The disease is non-progressive and in most cases asymptomatic, with mild photophobia reported by some patients.

Normally, asymptomatic cases are not treated.