An ABC-ELISA for malaria serology in the field.

An avidin biotin peroxidase complex enzyme-linked immunosorbent assay (ABC-ELISA) was examined for the diagnosis of malaria in a controlled area in Sudan Gezira. The titers of the ABC-ELISA coincided with those of the IFAT. The method was more sensitive than the ordinary ELISA as the final enzyme reaction was amplified through the use of the ABC system. This allowed the resulting color spots on the dried plate wells to be read clearly with the naked eye. This test can be carried out without using major electrical equipment.

Control of schistosomiasis in the Gezira.

For the control of schistosomiasis in irrigated agricultural schemes, the inhabitants must have:- 1) Enough potable water. 2) Latrines. 3) Proper health education to motivate the community to participate in the control. 4) Proper diagnostic facilities. 5) Proper available chemotherapy. 6) Focal mullusciciding. 7) If possible trial of biological and environmental methods of control. Following the above methods, we could reduce the prevalence of schistosomiasis from over 50% to about 13%. The important achievement, is the improvement of the health of the community; therefore more production and reduced morbidity and mortality.

Control of schistosomiasis in the Gezira

For the control of schistosomiasis in irrigated agricultural schemes, the inhabitants must have: 1) Enough potable water. 2) Latrines. 3) Proprer health education to motivate the community to participate in the control. 4) Proper diagnostic facilities. 5) Proper availabel chemotherapy. 6) Focal mullusciciding. 7) If possible trial of biological and environmental methods control. Following the above methods, we could reduce the prevalence of schistosomiasis from over 50% to about 13%. The important achievement, is the improvement of the health of the community; therefore more production and reduced morbidity and mortality.

Control of schistosomiasis in the new Rahad Irrigation Scheme of Central Sudan.

As the new Rahad Irrigation Scheme in Central Sudan began its first agricultural season in 1978, the Blue Nile Health Project was being developed to prevent schistosomiasis and other water-associated diseases in the Rahad and Gezira-Managil schemes. Taken as an indication of overall transmission in the Rahad scheme, the prevalence of infection among children in the newly established schools was found initially to be 14% for Schistosoma mansoni and 1% for Schistosoma haematobium in 1980. In the older Gezira-Managil irrigation system nearby, where transmission had not been controlled there was also little S. haematobium but the prevalence of S. mansoni in school-aged children was rising above 70%. To avoid a similar future in the Rahad scheme an integrated control strategy was implemented in 1980 using chemotherapy and snail control, supported by safe water supplies in every village. Under this strategy the prevalence of S. mansoni in the schoolchildren was reduced below 10% by 1983 at an annual cost of less than $4 per capita, about $300 per square kilometer. S. haematobium remained at 1% in the schoolchildren in 1983. The major cost was for village water supplies with about 20% of the total going for snail control and 10% or less for chemotherapy. Over a third of the cost was for equipment and supplies purchased abroad, requiring hard currency. Economically feasible prevention of transmission in the long-term will require reduction of the annual cost to about $1 per capita. Cost reductions should be made primarily in operation and maintenance of the water supply systems and in snail control.

Protection of Sudanese irrigation workers from schistosome infections by a shift to earlier working hours.

Although schistosomiasis is an important occupational hazard for irrigation workers in Central Sudan, few measures have been found to protect them, short of abandoning the work. In an attempt to reduce their exposure to the large numbers of schistosome cercariae encountered in the water at midday, a group of Gezira canal cleaners were shifted to early morning working hours after being cured of their infections. They left the water each day at 10.00 hours, working from the canal banks thereafter. At the end of 6 months the prevalence of infections with Schistosoma mansoni was much lower in this group than in a similarly treated group with normal working schedules, indicating a practical way to protect irrigation and agricultural labourers.

Malaria control in the Gezira-Managil Irrigated Scheme of the Sudan.

The development of malaria control in the Gezira-Managil Irrigated Scheme of Central Sudan has gone through several phases. As a result of agricultural and irrigation practices in the Gezira, falciparum malaria transmission became perennial instead of seasonal and the mosquito vector developed resistance to several insecticides. Subsequent failure to maintain control led to serious epidemics after 1971. By 1975 malaria was again put under control through an annual round of house spraying with malathion from 1975 to 1980, and with fenitrothion since 1981. A proposal is outlined for a rational strategy for malaria control in the future.

The Blue Nile Health Project: a comprehensive approach to the prevention and control of water-associated diseases in irrigated schemes of the Sudan.

This is a general report on the Blue Nile Health Project in the Sudan. The project was initiated in 1979 to develop better strategies for controlling the major water-associated diseases in tropical irrigation schemes. The 10-year programme will cost about $154 million (1978 prices). The Gezira, Managil and Rahad irrigation systems, all irrigated from the Blue Nile River, were selected for the project area as typical of irrigation systems throughout Africa and the Middle East where malaria, diarrhoeal diseases and schistosomiasis are endemic, and as the areas most urgently in need of disease control in the Sudan. The methods used for control of the water-associated diseases emphasize permanent improvements in water supply and sanitation, in environmental and agricultural practices, in health education, community participation and primary health services, and a reduction in dependence on pesticides and drugs.

Use of the in vitro microtechnique for the assessment of drug sensitivity of Plasmodium falciparum in Sennar, Sudan.

In 1978, studies on the chloroquine sensitivity of Plasmodium falciparum were carried out in the district of Sennar, Sudan. The results of the in vivo tests showed parasites resistant at the RI level only, but the mean clearance time of trophozoites from the blood was higher than for strains found in many other areas of tropical Africa. The in vitro tests, using the microtechnique, indicated a lower sensitivity to chloroquine in the local P. falciparum isolates than in those of most other African countries. However, similar results have been reported from Ethiopia. The chloroquine sensitivity of P. falciparum from Sennar is close to the critical level of resistance. The in vitro microtechnique was also used to test for the sensitivity to Dabequin, 4-aminobenzo-quinoline, and was generally found to be a suitable and reproducible method, with a greater potential than the standard macro method. At parasite densities of over 100 000 asexual parasites per microlitre of blood the effect of a given concentration of chloroquine was related to the parasite density owing to the selective uptake of the compound by the parasitized cells.