Dracunculiasis, also known as guinea worm disease, is caused by the large female of the nematode Dracunculus medinensis, which emerges painfully and slowly from the skin, usually on the lower limbs. The disease can infect animals, and sustainable animal cycles occur in North America and Central Asia but do not act as reservoirs of human infection. The disease is endemic across the Sahel belt of Africa from Mauritania to Ethiopia, having been eliminated from Asia and some African countries. It has a significant socioeconomic impact because of the temporary disability that it causes. Dracunculiasis is exclusively caught from drinking water, usually from ponds. A campaign to eradicate the disease was launched in the 1980s and has made significant progress. The strategy of the campaign is discussed, including water supply, health education, case management, and vector control. Current issues including the integration of the campaign into primary health care and the mapping of cases by using geographic information systems are also considered. Finally, some lessons for other disease control and eradication programs are outlined

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Thiopurine methyltransferase (TPMT) activity determines biotransformation of azathioprine and, thereby, drug efficacy and safety. Evaluation of a possible long-term effect of mesalazine or azathioprine on TPMT activity is of particular clinical importance because both drugs can to be given for several years in inflammatory bowel disease. Monitoring of TPMT activity and three thiopurine metabolites was performed prospectively during a 1 year postoperative period in 21 patients with Crohn's disease randomly assigned to azathioprine (2.0-2.5 mg/kg per day) or mesalazine (4 g/day). TPMT activity did not change significantly within each treatment group during 52 weeks. At any study visit, TPMT activity was not different between 13 patients on azathioprine and eight patients on mesalazine. Concentrations of 6-thioguanine nucleotides (6-TGN, active moiety of azathioprine) and 6-methyl-mercaptopurine ribonucleotides (6-MMPR) did not alter significantly during the observation period, except for a slight decrease in 6-TGN levels when comparing the first with the last visit. In this first report of serial monitoring of 6-methyl-thioguanine nucleotides (6-MTGN) in patients with inflammatory bowel disease taking azathioprine, high levels of 6-TGN were correlated with high levels of 6-MTGN, with the mean 6-TGN:6-MTGN ratio being 2.4. In a well-standardized clinical setting of inflammatory bowel disease, neither mesalazine nor azathioprine significantly affected TPMT activity during a whole year of treatment.

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Observations on the course of Hymenolepis nana infection in immunosuppressed mice are presented. Treatment of the host with hydrocortisone acetate caused superinfection of the bowel with worms and the development of normal cysticercoids in the mesenteric lymph node and liver. Natural infection of mice deprived of their T-cells by pre-adult thymectomy and administration of antithymocyte serum resulted in superinfection and widespread metastasis of aberrant cysticercoids that were greatly enlarged and without scolices, causing death after about five months. The significance of these findings and their possible relevance to human infection with H. nana are discussed.

The model of Onchocerca lienalis microfilariae (mf) injected into inbred CBA/Ca mice was studied for its usefulness as an additional primary/secondary drug screen for onchocerciasis. Invermectin, DEC, suramin, flubendazole, mebendazole, levamisole, Mel W, furapyrimidone, metrifonate, amoscanate and the new Ciba-Geigy compounds CGP 6140, CGP 20'376 and CGI 17658 all significantly reduced levels of mf at a dose of 5x100 mg/kg or less. An early dosing protocol, on days 3–7 after infection, was found to be generally more effective than dosing on days 11–15, followed by necropsy on day 18. In some cases there were important differences in levels of drug activity depending on whether the drug was administered by the subcutaneous or oral route, indicating that new compounds should be tested via both routes. Ivermectin was by far the most active compound examined, virtually clearing mf from the skin at a dose of 5x0.0063 mg/kg and producing a significant mf reduction (63.5%) at 5x0.008 mg/kg following subcutaneous administration. In comparison, DEC was much less active, producing a 32.4% mf reduction at 5x25 mg/kg ranging up to a maximum of 72% reduction at 5x100 mg/kg. CGI 17658 was the most active compound examined next to ivermectin, almost 100% effective against skin mf at a dose of 5x6.25 mg/kg via the oral route while being less effective via subcutaneous administration (65% reduction). The lowest effective dose examined was 5x3.13 mg/kg (per os) which reduced mf levels by 64%. CGP 20'376 was also very active, resulting in a 46% (subcutaneous) and 62% (per os) reduction at a dose of 5x6.25 mg/kg. This mouse model has clearly identified all the known microfilaricides examined and also, to a lesser extent, those compounds considered to be principally macrofilaricides. We believe it has value as an additional drug screen for onchocerciasis, which will enable the evaluation of novel compounds against skin-dwelling Onchocerca mf at the primary/secondary level, providing complementary information to new in vitro screens using adult Onchocerca.

The relationships between intestinal parasitism and excreta disposal technologies in Gaborone (Botswana), Ndola (Zambia) and Kumasi (Ghana) were investigated. Parasitic prevalence and intensity rates amongst groups of urban residents having similar socio-economic status and housing, but different excreta disposal technologies, were compared. In Gaborone, there was no evidence of a difference in intestinal parasitism between those using aqua privies and having access to public taps and those in identical houses enjoying flush toilets, in-house water connections and showers. In Ndola, the group with sewered aqua privies had larger houses, cleaner toilets, better water supplies, longer residence and more people in paid employment than the groups using pit latrines or communal flush toilets. Despite this, the sewered aqua privy users were not found to be different from the other groups with regard to hookworm and protozoal infection but had significantly higher Ascaris infection rates. In Kumasi, despite the differences in toilet type--from squalid communal aqua privies, through often fouled bucket latrines to well-maintained flush toilet systems--and despite also the differences in water provision, no evidence was obtained of any differences in intestinal parasitism between the groups studied. These findings suggest that the provision of superior water and sanitation facilities to a small cluster of houses, or to houses scattered through an area, may not protect those families from infection if the over-all level of faecal contamination of the environment is high. The sample sizes and response rates achieved in this study were low and follow-up studies, employing the same methodology but with larger samples, are recommended.