Prof Meir Broza and Dr Yechezkel Kashi have found a biotic association between V.cholerae and the non-biting midges (chironomids), one of the most common invertebrate groups in freshwater; and also the potential of these airborne adult midges to serve as vectors of the disease.
The paper includes evidence and small scale experiments suggesting that adult non biting midges, a highly mobile flying insect group (Chironomidae), are the vectors that may support continental and intercontinental distribution of cholera. Until 1967, researchers believed that humans may be the reservoir of cholera disease in the inter-epidemic period. In 2001, the University of Haifa team, led by Prof Meir Broza suggested that egg masses of non biting midges serve as a natural reservoir of cholera. It was discovered quite 'accidentally'.
Broza explains: "We were looking for a safe way to control nuisance midges in an Israeli drinking water system. One day hundreds of egg masses were brought to the lab and left overnight. The next morning they had apparently vanished. We discovered that V. cholerae serogroup O9 was the microbial agent responsible for digesting the egg masses and making them disappear."
A cooperative study by both Israeli groups showed that the most abundant protein secreted by V. cholerae is a protease used by bacteria to utilize the gelatinous like matrix of the midge egg masses as a nutrition source for their growth.
In the second phase of the research they asked; could these waterborne bacteria, which grow and multiply in egg mass
Contact: Lucy Mansfield
Blackwell Publishing Ltd.