In a letter to the editor in the March 2013 issue of Emerging Infectious Diseases, the Hong Kong Department of Health writes about the first known outbreak of the microsporidium Vittaforma cornea. The outbreak occurred during an international rugby tournament and caused 160 infections in athletes from five different countries.
Microsporidia are spore-forming parasitic organisms that occasionally cause infections of the eye cornea in animals. The parasites are considered an emerging infection in both humans and animals with fifteen known species that infect the human digestive tract and the cornea of the eye. Infections of the cornea, known as microsporidial keratitis or keratoconjunctivitis, usually resolve on their own and do not generally need treatment. Symptoms include eye pain, discharge, blurred vision, swelling and itchiness.
The microsporidium Vittaforma corneae has a widespread global distribution and infection with this particular species is largely associated with exposure to hot springs, dirty water and soil. The spores of V. cornae are common to Singaporean soil and over the past decade the country has seen an increase in cases of V. cornae infection that have involved eye contact with soil. Athletes playing contact sports on grassy pitches or turf have shown to be at higher risk of acquiring the infection.
Over 1600 school-age athletes from 16 rugby clubs from Singapore, Malaysia, Hong Kong, Australia and the United Arab Emirates participated in the tournament from April 21 to April 22, 2012. The outbreak began four days later and lasted until May 22. All five countries were struck by the outbreak, although with a 37 percent increase of infections relative to other nations, athletes from Hong Kong was disproportionately affected.
Health officials from Hong Kong and Singapore note that athletes experienced heavy rainfall and excess mud on the playing field throughout the tournament; it has been suggested that these environmental conditions may have been responsible for the spread of the outbreak by increasing the likelihood of eye contact with soil.
Infections and outbreaks among athletes that play contact sports are not uncommon, though they tend to be infections of the skin and soft-tissue and are generally caused by bacterial, fungal and viral organisms. This is the first known incident of an outbreak in athletes caused by a microsporidium parasite and is notable for its broad international impact.