A case report of a Hymenolepis diminuta infection in a child in St James Parish, Jamaica

Hymenolepis diminuta is a tapeworm which is an intestinal parasite of rats and mice. Rarely, through accidental ingestion of an infected arthropod, man can become the definitive host. This report documents, for the first time, that such infections occur in Jamaica, West Indies. The life cycle of the parasite and its treatment are also discussed. (AU)

Routine focal mollusciciding after chemotherapy to control Schistosoma mansoni in Cul de Sac valley, St. Lucia

Concluding results of a ten year schistosomiasis control programme in Cul de Sac valley, St. Lucia, are described. After an area wide mollusciciding campaign (1970-1975), and a surveillance/treatment programme supplemented with selective population chemotherapy in 1975 and 1976, prevelence rates of Schistosoma mansoni were reduced to low levels. To prevent a resurgence of transmission a cost effective routine focal mollusciciding programme, suitable for public health implementation was evaluated from 1977 to 1981. Streams and main collector drains in banana fields, considered to be potential S. mansoni transmission sites, were treated every four weeks with Bayluscide 6076 emulsifiable concentrate (Clonitralide). Snail populations were effectively controlled in the treated areas but large numbers were present where no treatment was given. Only 0.06 percent of sentinel snails became infected. Prevalence of infection in the human population remained low (over-all 5 percent) and intensity of infection at a level not normally associated with schistosomal disease. Since control started ten years earlier the level of potential contamination has fallen by 92 percent in high transmisssion areas. The four year programme cost US$12,909, of which 54 percent was for molluscicide, 27 percent for labour and 19 percent for transport, equipment and sundries. The average annual cost per head of population was US$0.46

Reduction in transmission of Schistosoma mansoni by a four-year focal mollusciciding programme against Biomphalaria glabrata in St. Lucia

The effect on transmission of Schistosoma mansoni of a focal snail control programme was investigatsd over four years amongst approximately 1250 people living in 5 communities in the steep-sided Soufriere river valley, St. Lucia, West Indies. Bayer 6076 was applied from constant flow drip cans to 12 stream sections at a target dose of 8mg/litre clonitralide every four weeks. Only proven and potential transmission sites were treated (AU)

Evaluation of an experimental mollusciciding programme to control Schistosoma mansoni transmission in St Lucia

The size and number of colonies of Biomphalaria glabrata were reduced after four years of a surveillance/treatment snail control programme using an emulsifiable concentrate of niclosamide (25 percent active ingredient). Surveys among the human population showed that the incidence of new Schistosoma mansoni infections in 0-10 year-old children fell from 22 percent to 4.3 percent, while in a comparison area the incidence remained at 20 percent. With the reduced transmission over four years, the prevalence of infection in a cohort of children examined in 1971 and 1975 fell from 34 percent to 23 percent. The fall in prevalence and intensity of infection led to a reduction of 66 percent in the index of potential contamination, which was reflected in a reduced rate of infection among sentinel snails and representative samples of B. glabrata collected during surveillance searchs. The overall annual cost of the programme was US $3.24 per capita (AU)

Persistence of the molluscicide Bayluscide (clonitralide) emulsifiable concentrate on mud surfaces in the tropics

Clonitralide (the active ingredient of the molluscidide Bayluscide) is commonly regarded as non-persistent. It was importnt to determine if this assuption was correct during the development of a programme on St. Lucia to control the intermediate host of Schistosoma mansoni, the snail Biomphalaria glabrata. In 3 separate experiments, aqueous solutions of an emulsifiable concentrate of clonitralide were sprayed onto pans containing dried mud or mud covered with 2.5 cm of water. All snails present at the time of spraying were killed, whether or not water was present. Mortalities were high in similar, unsprayed pans but subsequent chemical and biological assays demonstrated that clonitralide remained active for over a year in tropical conditions, despite several cycles of wetting and drying. Clonitrlide residues from vegetation sprayed in an operational snail control programme remained toxic for 8 weeks exposed to full sunlight, heavy rainfall, temperatures of 20 to 30 degrees C and relative humidities of 70 percent to 95 percent. The implications of these findings for the control of aquatic and amphibious snails are discussed together with some possible mechanisms to explain the persitence of the molluscicide.(AU)