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A total of 3443 people were screened by ultrasound to determine the prevalence of hydatid disease in southern Sudan. Hydatid cysts were found in 16 (0.5%) of the people screened. Thirteen of the 16 hydatid cases were from among the Bouya people who showed an overall hydatid prevalence of 2% by ultrasound. All ultra-sound positive cases were further confirmed by dot-blot ELISA. At the time of the survey, Chukudum Hospital had five cases with histories and clinical manifestations consistent with hydatidosis. However, on scan examination only three of them were confirmed to be cases of hydatid disease. The proportion of hydatid infected women in south-western Sudan was almost twice that of men (M:F ratio of 1:1.7), with most of those infected being women in the child-bearing age bracket. Dogs are common in this area and they could be the main reservoirs of Echinococcus granulosus in the Sudan. Due to the low prevalence of hydatid in humans in the study area, and the dispersed nature of the population, it is recommended that hydatid control measures for south-western Sudan include an educational component coupled with treatment of the infected people.

The prevalence of malaria in the human population of southern Sudan was studied during March to April, 1996. A total of 330 people including adults and children were screened for malaria by microscopic examination of Giemsa stained thick and thin blood smears prepared from a finger prick sample. Plasmodium falciparum was the only malaria parasite detected in blood smears in the present study, even though hospital records indicated presence of P. vivax. About 24.5% of those examined were infected. .

Onchocerciasis is endemic in southern Sudan. The prevalence in human population may range from 10% to 40%. In the Eastern Equatorial Region of Southern Sudan, more cases are found in Nimule on the Sudan-Uganda border than in rural highlands of Labone and Chukudum basins. Onchocerciasis was highest in males (with a prevalence of 70.2% based on data from hospital records)) than in females, with prevalence of 19%. Overall, prevalence of onchocerciasis in children was 10.8%.Considering cost-effectiveness, public health priorities and the security situation in this area, we recommend active search on onchocerciasis cases in the community and treatment.

The larval forms of Echinococcus granulosus were surgically removed from Turkana hydatid patients and studied on the electron microscope. It was found that the larval forms "hydatid cyst" consists of a protective laminated layer that surrounds the germinal layer. The germinal layer is made up of numerous germinal cells that transform to brood capsules within which protoscolices are formed. Protoscolices are formed from accumulations of undifferentiated germinal cells. The brood capsule wall is similar to germinal layer and they were found to contain numerous invaginated protoscolices. The invaginated protoscolices were of various sizes and they were not attached to the wall of the brood capsule. The evaginated protoscolex has two body regions, the head (scolex) and body (soma). The scolex is covered by numerous long microtriches whereas the soma is covered with few short microtriches.

A fundamental feature of Echinococcus granulosus infection is its chronicity. There are many reasons for this, including weak natural immunity and the ability of the larval stages to evade or resist elimination by the hosts' specific immune responses. To identify the types of hosts' cellular immune response, a series of ultrastructral studies of hydatid cysts surgically removed from Turkana patients was conducted based on transmission electron microscopy. Ultrastructurally, the ectocyst (adventitial layer) is organised into three layers; an inner layer containing mainly the infiltrating mononuclear leukocytes; a middle, loose connective tissue layer with inflammatory cells mainly plasma cells, fibroblasts, scant neutrophils, eosinophils and lymphocytes, and an outer loose connective tissue layer that blends with the surrounding host tissue. The mast cells and basophils were not observed. This study has showm that the adventitial layer of hydatid cysts infiltrated by leukocytes, principally by macrophages and plasma cells.