50 years ago: Scope of mosquito issues highlighted

George-Town-50-years-finalIn the Oct. 19, 1966 edition of the Caymanian Weekly, a precursor of the Cayman Compass, news from George Town included:

“Dr. M.E.C. Giglioli has informed the Caymanian that the Mosquito Research and Control Unit has recently been granted 41,329 pounds from Colonial Development and Welfare funds to cover capital equipment costs during its first two years of operation ending in April 1968.

“In his memorandum (7 foolscap pages) to the Secretary of State for the Colonies, Dr. Giglioli sets out the methods, reasons and chronology of the work proposed by the Unit over the next 3-4 years.

“Naturally the rate at which progress can be made, now that funds are available, depends on the rate of supply of capital equipment. In this the Unit are totally dependent on the manufacturers and shippers. For example, delays in the delivery of a dragline (now due to arrive in January) inevitably set back the chronology of the whole scheme and, unfortunately, there is nothing that the Unit can do to resolve such unforeseen delays except to be patient which must be very trying for them when the general public are somewhat impatient for action …

“Under the heading ‘Objects and Reasons’ [in his memorandum] are two points:

“1. The extremely high densities of nuisance, salt-marsh mosquitoes found in the Cayman Islands prevent the extension of the tourist season and present a threat to this industry which constitutes the basis of the Islands’ economy.

“2. Although these islands enjoy a reputation for being healthy and free from endemic mosquito-borne diseases, vector species exist locally and the danger of epidemics, if and when a pathogen is introduced, exists as an ever present threat to health. (Malaria epidemics of varying intensity have been reported in 1957, 1936, 1930, and 1929, with several deaths in 1934 in West Bay.)

“It might have also been added that the residents who have put up with this pest in its millions for their lifetime would be rather relieved to have it removed too!

“When commenting on his scientific observations so far, Dr. Giglioli records peak collections per night, per trap during the dry season (following rainfall, lunar or wind tides) were in the order of 1000-5000 mosquitoes. By comparison, the peak collection for one trap during the night, in the initial high densities of this year’s mosquito season were as follows: Aedes Taeniorhynchus 96,000 other, 6 species 90.

“The 1966 mosquito season ‘exploded’ in mid-May …

“It is obvious that figures in excess of 10,000 mosquitoes per trap per night are common during the rains, and that these are mainly salt-marsh mosquitoes, the eggs of these species resist 3-6 months dessication and are laid in mangrove areas and salt flats covered by low succulent halophyten. These mosquitoes lay their eggs only on damp soils and not directly on water as is usual with other species, this characteristic is used successfully in controlling the species by permanently flooding the breeding ground and thus depriving them of their egg laying sites.

“Among the relatively low proportion of other species recovered, Culex nigripalpus, the vector of encephalities (Florida, 1962, Jamaica, 1963) is disturbingly high.”