US and Haitian health officials said Monday that the strain of cholera in the deadly outbreak in Haiti is not from the impoverished, quake-ravaged island, but similar to strains found in South Asia.
Tests using pulsed field gel electrophoresis (PFGE) on bacterial isolates recovered from patients with cholera in Haiti, conducted by the US Centers for Disease Control and Prevention (CDC) found all 13 isolates to be identical and also indicated that they were the same as a strain found in South Asia.
The strain was identified last week by Haiti's National Public Health Laboratory (NPHL) as Vibrio cholerae serogroup O1, serotype Ogawa.
"Although these results indicate that the strain is non-Haitian, cholera strains may move between different areas due to global travel and trade," said Haitian Minister of Health Alex Larsen.
"Therefore, we will never know the exact origin of the strain that is causing the epidemic in Haiti. This strain was transmitted by contaminated food or water or an infected person," he said.
Global travel and trade provide many opportunities for infectious diseases such as cholera to spread from one country to another, the CDC said.
"In most instances, cholera does not spread widely within a country if drinking water and sewage treatment are adequate. When water and sewage treatment is inadequate, as in post-earthquake Haiti, cholera can spread rapidly," the US federal health agency said.
Additional laboratory testing, including whole genome DNA sequencing, is being conducted on the cholera strain, but even those tests may not explain how cholera was introduced into Haiti, the CDC said.
"Our primary focus here is to save lives and control the spread of disease," said CDC medical epidemiologist Jordan Tappero, who is leading the CDC cholera response team in Haiti.
"We realize that it's also important to understand how infectious agents move to new countries. However, we may never know the actual origin of this cholera strain," Tappero said.