Medical Officer's annual report [to] Durban Corporation.

  • Durban (South Africa). Public Health Department.
Date:
[1949]
Catalogue details

Licence: Public Domain Mark

Credit: Medical Officer's annual report [to] Durban Corporation. Source: Wellcome Collection.

    29/60 (page 27)
    5. PLAGUE AND MEASURES TAKEN AGAINST PLAGUE PROOFING OF STORES AND OTHER BUILDINGS. RODENTS INCLUDING RAT- During the year, the Home Disinfection Unit, previously controlled by the City Fever Hospital, was seconded to the Field Hygiene Section. The staff, accordingly, was increased by one European General Assistant and one Indian Labourer. The only re-arrangement of existing staff was the allocation of one General Assistant (European) to full-time employment with the eight Native Health Assistants on surveys of Anopheline mosquito breeding foci. All anti-pest measures were well maintained and, on the whole, results were very satisfactory. MOSQUITOES : Field experiments with phenolic sprays and D.D.T. emulsion as larvicides were carried out during the year. As a result, phenolic materials were regarded as being unsatisfactory for use in Durban, by reason of their rapid decomposition in the presence of ‘ organic ’ matter (rotting vegetation, etc.) in swamp areas under treatment. D.D.T. in most instances gave excellent results. Exceptions were in pools polluted with household waste- water. Soap and other scum present caused most of the D.D.T. crystals to clot, so preventing contact with larvae. Thus, repeated applications of emulsion were required to kill the first, second and third stage larvae, whilst fourth stage larvae and pupae remained virtually unaffected. In the absence of surface scum, D.D.T. gave highly satisfactory results particularly in view of the low concentration used, i.e., 0 08% D.D.T. Experiments with emulsions continue and should result in establishing the efficacy of D.D.T. under al conditions. With improved emulsifying agents and spraying technique, it should be possible to force the D.D.T. solution well under the surface of the water being treated. Oil as a larvicide should be entirely superseded by D.D.T. before long. The normal anti-mosquito programmes of oil-spraying, ditch digging and cleaning, reclamation and bush removal were maintained. ENTOMOLOGY : Of 9,030 Anopheline larvae collected, none was a Malaria vector. The following species were identified : A. Leesoni. 68 A. Marshalli. ... 5 A. Demeilloni ... 2,492 A. Squamosis ... 2 A. Maculipalpis ... ... 531 A. Squamosis Var. ... 57 A. Pretoricnsis ... ... 2,773 A. Longipalpis ... 14 A. Cinereus ... 2,408 A. Natalensis ... 18 A. Coustoni. ... 661 A. Ardensis . ... 1 BUGS : The anti-cimex programme in Municipal institutions employed D.D.T. alone or D.D.T./B.H.C. solutions. The lasting results obtained with these materials indicate their superiority to Hydrogen Cyanide, which is no longer used by the Department. ROACHES: Benzene Hexachloride and D.D.T. in solution has proved its efficacy in dramatic fashion. The roach has almost vanished from Municipal premises under regular control. This applies particularly to the much maligned sewerage system where manholes treated at intervals of 10 to 12 weeks remain entirely free of roaches. The roach problem to-day is confined to private premises and, in the main, it is an educational problem, i.e., to instruct the public in proper methods of applying the new insecticide. A pamphlet ‘ Family Forum No. 6 ’ on the subject is now being prepared and, on completion, will be issued to all householders. Practical demonstrations in restaurant kitchens have proved conclusively that the roach can be eliminated. PLAGUE AND RODENT CONTROL: The programme of rodent destruction, coupled with sampling for Plague index, proceeded without respite. Cyanogas dust, supplemented by poison baiting and trapping, were the chief weapons of destruction. Of the poisons, phosphorus was chiefly relied on, barium carbonate being no longer used. Arsenic and strychnine were used under favourable conditions. Some 10,521 rodent carcases were recovered, of which 953 were examined for B. Pestes with negative results. There was full co-operation between the Rodent Staff and District Health Inspectors. Numerous rodent¬ proofing programmes were carried out as a result of close liaison between the Rodent staff and District Health Inspectors. FLIES AND LICE : To forestall outbreaks of Typhus and Typhoid Fever at refugee camps, used in connection with January riots, all horizontal surfaces were dusted with 10% D.D.T. in talc. All vertical surfaces were sprayed with D.D.T. and Benzene Hexachloride solution. Further, all areas fouled with waste-water and dejecta were dosed with disinfectant. Every assistance was given to Health Visiting staff in ‘ body-dusting ’ louse-ridden refugees. This treatment was repeated where the need was indicated. Complete freedom from flies and a remarkable absence of illness in the forty-seven camps concerned prove the value of the pest control measures adopted. HOUSE DISINFECTION : The normal programme of disinfection of furniture and rooms by Formalin and removal of bedding and clothing to a steam disinfector was maintained. STATISTICS : Rodents : Premises trapped for Plague index Baits laid . Traps set . Cyanogas used—lbs*. Rodent carcases recovered Rodents examined for B. Pestis 2,003 123,130 21,624 l,056i 10,521 953