RESUMEN

The Itwara focus of onchocerciasis covers an area of approximately 600 km(2) in western Uganda about 20 km north of Fort Portal. The vector is Simulium neavei, whose larvae and pupae live in a phoretic association on freshwater crabs. The phoretic host in the Itwara focus is the crab Potamonautes aloysiisabaudiae. Before any onchocerciasis control, ATPs were estimated to reach between 4500 and 6500 infective larvae per person per year. S. neavei was found to be a very efficient vector with 40% of parous flies harbouring developing larvae of Onchocerca volvulus. After 4 years of community-based distribution of ivermectin transmission was still considerable and in 1995 monthly treatment of streams with the larvicide temephos commenced in the first of three sub-foci, and was gradually extended to the whole focus. Biting S. neavei disappeared from the first sub-focus (Itwara main) in June 1996, and the last infested crab was caught in November 1996. In the second sub-focus (Siisa) treatment commenced towards the end of 1995, and the last biting fly was caught in March 1997, but a deterioration in the security situation interrupted the programme (after only three treatments in the third sub-focus). Monthly treatments restarted in the second and third sub-foci (Aswa) in September 1998, and when the situation was reassessed in 2003 no biting flies were found anywhere, and the flies had not reinvaded the first sub-focus, but infected crabs were found in the second and third sub-foci. The last treatments were carried out in April-June 2003, and since then no infested crabs have been found. In summary, no S. neavei-infested crabs have been found anywhere in the focus since June 2003 and the vector is considered eliminated from that date. However, transmission had already been halted since February 2001, when the last biting flies had been collected. The parasite reservoir should die out in the human population by 2016.

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The national onchocerciasis-control programme in Uganda successfully eliminated Simulium neavei s.s. from the Itwara focus in 1997, by monthly ground spraying with larvicidal temophos (Abate). Since then, no vectors have been caught in the main Itwara focus or two secondary foci in the same area. After 4 years of intervention, S. neavei s.s. has also been nearly eliminated from the Mpamba-Nkusi focus, and the elimination of this vector from two more foci (West Nile and Wambabya-Rwamarongo) appears quite feasible. There are, however, four isolated foci in Uganda (Budongo, Kashoya-Kitomi, Mount Elgon and Kigezi-Bwindi) which are probably too large and inaccessible to make the elimination of S. neavei s.s. by ground spraying a realistic possibility. Encouragingly, >70% of Ugandans have received an annual dose of ivermectin for at least 10 years, and the national programme of community-directed treatment with ivermectin (CDTI) is thought to be progressing towards sustainability. Despite the good treatment coverages, however, many potential vectors are still found infected with Onchocerca volvulus and many Ugandans have O. volvulus in their skin. There is now evidence that adult O. volvulus can be eliminated, within a period of about 6 years, through semiannual treatment with ivermectin. Together, the isolated foci where vector elimination is not considered feasible have a human population of about 700,000, most of whom (595,000) are eligible to receive ivermectin treatment. The estimated cost of each treatment, via the Ugandan CDTI, is U.S.$0.78 if the salaries of the government-employed personnel and the working time lost by the volunteers who act as community-directed drug distributors (CDD) are taken into account. If these 'expenses' are ignored, however, the cost falls to just U.S.$0.17/treatment, and the total costs for the four isolated foci where vector control is not likely to be successful become about U.S.$101,150/year for annual treatment (for an indefinite period of time) or approximately U.S.$202,300/year for semi-annual treatment (for the 6 years needed to eliminate adult O. volvulus), which would be the more cost-effective option. With the necessary financial support and the continued free supply of ivermectin from Merck, the national onchocerciasis-control programme could eliminate human onchocerciasis from Uganda, through a combination of semi-annual treatment with ivermectin in the isolated foci where S. neavei s.s. elimination is not feasible, and vector elimination in all the other foci.

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The transmission of Onchocerca volvulus Leuckart (Spirudida: Onchocercidae) and the prospects of Simulium neavei Roubaud (Diptera: Simuliidae) vector elimination through ground larviciding were investigated in the Mpamba-Nkusi focus, western Uganda. Transmission levels and the initiated vector elimination activities were assessed to supplement the ongoing ivermectin mass distribution programme. Searches for breeding sites, adult fly catches, dissection of flies, river treatment with temephos (Abate) and a review of annual ivermectin treatment data were conducted. High levels of crab infestation with S. neavei sensu stricto immature stages were recorded; 57.9% and 100% for the Mpamba and Nyabugando river systems, respectively. The mean numbers of larvae/pupae per crab were 3.6 +/- 0.5 in the Mpamba and 20.6 +/- 1.8 in the Nyabugando systems. Pre-intervention mean biting densities were 39 and 32 flies/(man day) in 2001 and 2002, respectively, and an annual biting rate in 2001 of > 14 000. The bimodal biting pattern of S. neavei s.s. consisted of two peaks; one in the morning (09.00-10.00 hours) and one in the afternoon (14.00-15.00 hours) with a mid-day lull in biting. The infection/infective rates were 13.3%/2.8% and 16.6%/2.9% in the dissected parous flies from the Mpamba and Nyabugando river systems, respectively. Out of approximately 1000 parous flies, 129 and 109 were found to be harbouring infective larvae of Onchocerca volvulus in their heads from the Mpamba and Nyabugando river systems, respectively. In spite of the > 10 years of ivermectin treatment, at a mean coverage of 71.3%, infection remained relatively high. Ground larviciding with temephos (Abate) initiated in June and October 2002 had a significant impact. In the Mpamba river system there was a significant (P < 0.001) reduction in positive crabs from 57.9% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 3.6 +/- 0.5 in 2001 to 0.0007 +/- 0.0001 (P < 0.002) in 2003. Similarly, in the Nyabugando river system, a significant (P < 0.001) reduction in crab infestation from 100% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 20.6 +/- 1.8 in 2001 to 0.06 +/- 0.03 in 2003. Drastic reductions were observed in the mean number of biting flies from 3 flies/h in 2001 to 0 flies/h in 2003 and the annual biting rates fell from 14,235 flies/year in 2001 to only 730 flies/year in 2003. These data suggest that substantial progress towards the goal of S. neavei s.s. vector elimination has been made and this will enhance the ongoing ivermectin treatment in this isolated focus.

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Community-directed treatment with ivermectin (CDTI), for the control of onchocerciasis, was launched in Uganda in 1997. In East Africa, as in other endemic areas, the refusal to take the drug reduces treatment coverage and therefore poses a serious threat to attempts to eliminate onchocerciasis as a disease of public-health importance. In early 2003, an attempt was therefore made to determine the factors associated with refusal to take ivermectin during mass treatment in 2002, by interviewing the individuals, from three Ugandan villages with CDTI, who had been eligible to receive ivermectin. The subject's socio-demographic characteristics, history of adverse reactions and participation in CDTI-related activities were explored, as potential 'risk' factors for refusing ivermectin in the treatment round in 2002. When odds ratios (OR) for refusal and their associated 95% confidence intervals (CI) were calculated, the villagers aged 18-35 years were found more likely to have received ivermectin in 2002 than their older counterparts (OR = 0.55; CI = 0.33-0.93). Individuals with an inter-current medical condition were also more likely to have received ivermectin in 2002 than the other villagers (OR = 0.56; CI = 0.32-0.99). Worryingly, the ingestion of ivermectin at any time before the 2002 treatment round was strongly associated with refusal to take ivermectin in that round (OR = 7.72; CI = 2.00-29.81), although there was no evidence that the adverse effects of treatment were significantly reducing coverage.

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A retrospective study based on paediatric ward registers was conducted in the Ugandan districts of Hoima and Kabale, which are areas of stable and unstable malaria transmission, respectively. The records of Hoima hospital from 1990 to 2001 and of Kabale hospital from 1994 to 2000 were reviewed and the initial diagnoses for all young children (i.e. those aged <5 years) were noted. Admissions for malaria and for anaemia were significantly more common among the young children admitted to Hoima hospital than among those admitted to Kabale hospital (P<0.0001 for each). Over the study periods, there were significant linear increases in the numbers of young children admitted with malaria or anaemia, at both Hoima hospital (with chi2 values of 25.6 and 191.5, respectively; P<0.0001 for each) and at Kabale hospital (with chi2 values of 31.6 and 29.0, respectively; P<0.0001 for each). Anaemia was not an important cause of mortality at Kabale hospital during the period reviewed. As in other sites in the East African highlands, the increasing malaria-related morbidity and mortality at Kabale hospital between 1994 and 2000 could be explained by the general increase in air temperatures over the same period. This increase may have made the local climate more conducive to mosquito survival and to parasite development in the vector, leading to increases in the intensity of transmission. At Hoima hospital, however, the increasing numbers of admissions for anaemia or malaria between 1990 and 2001 seem more likely to be the result of increased resistance to chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) in the parasites and to changes in treatment seeking behaviour. With the recent change in the national drug policy, from the use of CQ alone as the first-line treatment of uncomplicated malaria to the use of a combination of CQ with SP, and the abolition of user charges at government health facilities, a reversal of these worrying trends might be anticipated. Although it may be not be appropriate to extrapolate the conclusions of studies based on hospital records to the communities at risk of malaria, such conclusions do allow the health services to monitor general trends in the morbidity and mortality associated with malaria and anaemia.

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OBJECTIVE: To understand and elicit the factors influencing compliance with mass treatment with ivermectin for onchocerciasis control with a view of suggesting remedial measures. DESIGN: Qualitative methods using focus group discussion and individual key informant interviews. SETTING: Bushenyi district, Uganda. PARTICIPANTS: Fifty key informants who were local council chairpersons and community directed drug distributors (CDDs) for ivermectin. Five focus group discussions with community members. MAIN OUTCOME MEASURES: Explored knowledge about onchocerciasis and its treatment, consequences, benefits and perceived dangers of treatment with ivermectin. In addition the FGDs elicited information regarding social influence towards ivermectin treatment and who the source of social influences are. Perceived barriers and supports towards ivermectin treatment were also explored. The key informant interviews mainly elicited the problems they face in ivermectin distribution and their suggestions for improvement. RESULTS: Factors that could possibly influence mass treatment with ivermectin that were elicited include consequences of treatment, programme organization, charging for ivermectin distribution and programme/community support to the ivermectin drug distributors. CONCLUSIONS: These results are helpful in redirecting community education and in helping to design further quantitative research.

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Community-directed treatment is a relatively new strategy that was adopted in 1997 by the African Programme for Onchocerciasis Control (APOC), for large-scale distribution of ivermectin (Mectizan). Participatory monitoring of 39 of the control projects based on community-directed treatment with ivermectin (CDTI) was undertaken from 1998-2000, with a focus on process implementation of the strategy and the predictors of sustainability. Data from 14,925 household interviews in 2314 villages, 183 complete treatment records, 382 focus-group discussions, and the results of interviews with 669 community leaders, 757 trained community-directed drug distributors (CDD) and 146 health personnel (in 26 projects in four countries) were analysed. The data show that CDD dispensed ivermectin to 65.4% of the total population (71.2% of the eligible population), with no significant gender differences in coverage (P > 0.05). Treatment coverage ranged from 60.2% of the eligible subjects in Cameroon to 76.9% in Uganda. There was no significant relationship between the provision of incentives to CDD and treatment coverage (P > 0.05). The frequency of treatment refusal was highest in Cameroon (29.2%). Although most (72.1%) of the communities investigated selected their CDD on the basis of a community decision at a village meeting, only 37.9% chose their distribution period in the same way. There is clearly a need to improve communication strategies, to address the issues of absentees and refusals, to emphasise community ownership and to de-emphasise incentives for CDD. The investigation of the 'predictor indicators' of sustainability should enable APOC to understand the determinants of project performance and to initiate any appropriate changes in the programme.

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In the control of onchocerciasis using mass treatment with ivermectin, coverage needs to be monitored regularly so that communities with poor or insufficient coverage can be identified and timely and appropriate interventions then instituted. The aim of the present study was to assess whether ivermectin-treatment coverage in schoolchildren, as monitored by schoolteachers, could be used as a proxy of population coverage. Although the coverages estimated in schoolchildren were found to be significantly correlated with estimates based on household surveys (P=0.01), there was poor correlation between either school and household-survey coverage and the values recorded in community registers. Although the community-register figures are the ones which the district health services normally use to report treatment coverage, they may be unreliable. Ivermectin-treatment coverage in schoolchildren monitored by schoolteachers could give a good and more accurate approximation of total population coverage. Further, large-scale studies, that take into consideration the cost-effectiveness of the various methods available to validate reported treatment coverage, are recommended.

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A retrospective hospital record-based study for Uganda was conducted in Hoima district (an area of stable malaria transmission) and in Kabale district (an area of unstable malaria transmission). In-patient and maternity ward registers for January 1997-December 1998 were reviewed and malaria admissions, mortality, abortions, stillbirths and birthweights were recorded. Data were analysed in relation to rainfall patterns. Admissions due to malaria were significantly higher at Hoima compared to Kabale hospital in 1997 (P < 0.0001). However, the situation reversed in 1998 with significantly more malaria cases registered at Kabale compared to Hoima hospital (P < 0.0001). The increase at Kabale hospital in 1998 was attributed to increased and prolonged rains during 1997 (E1 Niño). Pregnancy was a risk factor for admission with malaria at Kabale, but not at Hoima. Anaemia was significantly more common among patients admitted to hospital at Hoima compared to Kabale in 1997 and 1998 (P < 0.0001 and P = 0.02, respectively). The rate of low birthweight (birthweight < 2.5 kg) was significantly higher among primigravidae and multigravidae at Hoima hospital compared to Kabale hospital (P < 0.0001). There were significantly more stillbirths at Kabale compared to Hoima hospital (P < 0.0001). Routine hospital data such as birthweight and number of malaria cases can provide information on the level of malaria transmission useful for the health services to target appropriate malaria interventions and allocate resources to control outbreaks of malaria epidemics.

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A study of knowledge, attitudes and practice was carried out in the Rukungiri district of Uganda, in order to investigate the involvement of women in community-directed treatment with ivermectin (CDTI), for the control of onchocerciasis. The data analysed came from interviews with 260 adult women (one from each of 260 randomly-selected households in 20 onchocerciasis-endemic communities), community informants, and participatory evaluation meetings (PEM) in eight communities. The women who had been treated with ivermectin in 1999 generally had more knowledge of the benefits of taking ivermectin, were more likely to have attended the relevant health-education sessions and were more involved in community decisions on the method of ivermectin distribution than the women who had not received ivermectin in that year. There were fewer female community-directed health workers (CDHW) than male CDHW in the communities investigated. The reasons for not attending health-education sessions, not participating in community meetings concerning the CDTI, and the reluctance of some women to serve as CDHW were investigated. The most common reasons given were domestic chores, a reluctance to express their views in meetings outside their own kinship group, suspicions that other women might take advantage of them, and a lack of interest. Most of the women interviewed (as well as other community members) felt that there were relatively few women CDHW. The women attributed this to a lack of interaction and trust amongst themselves, which resulted in more men than women being selected as CDHW. The rest of the community members were not against women working as CDHW. It is recommended that communities be encouraged to select women to serve as CDHW in the CDTI, and that the performances of male and female CDHW be compared.

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The prevalence of urinary schistosomiasis among the schoolchildren living in Kigogo administrative ward of the Kinondoni district of Dar-es-Salaam city, Tanzania, and the factors influencing the transmission of the causative agent, Schistosoma haematobium, were investigated in a cross-sectional study. The estimate of overall prevalence, based on microscopical examination of a single urine sample/subject, was 47.6%. Compared with the girls, the boys were more likely to be excreting schistosome eggs (54.6% v. 40.8%; P = 0.004) and had, in general, higher intensities of infection (54 v. 38 eggs/10 ml urine; P = 0.001). The children aged 10-14 years had higher prevalences and intensities of infection than those in the younger or older age-group studied. The sensitivity of micro-haematuria as an indicator of infection (compared with the microscopical examination of single urine samples) was 84.3% overall, reaching 92% among the children excreting > or = 50 eggs/10 ml urine. The corresponding positive and negative predictive values were 77% and 84%, respectively. The sensitivity, specificity and positive and negative predictive values of the history of haematuria as an indirect screening technique for S. haematobium were 60.4%, 72.7%, 67% and 67%, respectively. Recreational activities such as bathing, swimming and playing in the water were the most frequent activities attracting children to water bodies and carried the highest risks of infection with S. haematobium. Knowledge about the disease, especially on the symptoms and mode of transmission, was generally good but the methods of prevention were inadequately known. Chemotherapy to control urinary schistosomiasis in schoolchildren is recommended; infected children may be identified on the basis of haematuria, detected using questionnaires or reagent strips. Additional health education, to heighten awareness of the disease and its prevention, would also be beneficial.

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The effects of weekly chloroquine prophylaxis, daily iron-weekly folic acid supplementation or passive case management on maternal haemoglobin and parasitaemia and on birthweight were examined in primigravidae in a randomized, double-blind placebo-controlled intervention trial in 1996-98 in Hoima District, western Uganda. Iron-folic acid supplementation significantly increased mean birthweight as compared to case management (P = 0.03). Low birthweight (< 2.5 kg) occurred in 2% of babies of women receiving chloroquine prophylaxis for > or = 8 weeks and in 9% in the case management group (RR = 0.36, 95% CI 0.13-1.00, P = 0.009). Parasitaemia at enrolment significantly correlated with low birthweight in the case management group as compared to the intervention groups (P = 0.02). Women in the case management group who were parasitaemia and had haemoglobin levels < 100 g/L at delivery had babies with lower mean birthweight as compared to babies in the other groups (P = 0.04). Low haemoglobin level at enrolment, irrespective of parasitaemia status, was a predictor of low birthweight in the case management group only (P = 0.04). Chloroquine prophylaxis and iron-folic acid supplementation significantly increased maternal haemoglobin levels during pregnancy as compared to case management (P = 0.01 and 0.007, respectively) and the increase correlated to the duration of the intervention.

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In rural Ugandan communities where onchocerciasis is meso- or hyper-endemic, control of the disease is now being carried out using a strategy of community-directed programmes for the annual distribution of ivermectin to all persons eligible to take the drug. For these programmes to achieve their annual target coverage of at least 90% of the population eligible to take ivermectin, and to continue to sustain themselves for 10-15 years or more, even after external donor funding ceases, it has been found essential to replace the initial community-based strategy, imposed from outside, by a community-directed strategy developed by the community members themselves. Furthermore, it is essential for success that full use be made of the traditional social system, which is very strong in all rural communities in Uganda. This system is based on patrilineal kinships and clans, governed by traditional law, and in it women pay an important role. If this system is ignored or by-passed by government health personnel or by the sponsors and promoters of the programme, the communities are likely to fail to reach their targets. When rural communities increase in size and complexity, following development and the arrival of migrant families, they become semi-urbanized. The kinship/clan system is then weakened, community-directed drug distribution is much more difficult to organize, and coverage targets are not often achieved. This effect is of minor importance in a rural disease, such as onchocerciasis, but is likely to be of greater significance in the control of diseases, such as tuberculosis and lymphatic filariasis, which thrive in urban environments.

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Sensitivity of Plasmodium falciparum to chloroquine and sulfadoxine-pyrimethamine was tested among asymptomatic school children in 1995 and 1998 using a modified in vivo test with examination for parasitaemia on day 0, 2 and 7. Sensitivity (S/RI) to chloroquine in 'urban' areas was found in 42% in 1995 and 62% in 1998 with resistance at the RII/RIII level observed in 58 and 38%, respectively (P<0.01). In 'rural' areas, sensitivity to chloroquine was 76% in 1995 and 72% in 1998 (P=0.6) with resistance at the RII/RIII level observed in 24 and 18%, respectively (P=0.4). Sensitivity to sulfadoxine-pyrimethamine was found in 98 and 99% in 1995 and 1998, respectively. The apparent improvement in sensitivity to chloroquine in 'urban' areas might be due to a different school being included in the two studies. It is concluded that the pattern of sensitivity of P. falciparum to chloroquine and sulfadoxine-pyrimethamine has not changed over a period of 2.5 year.

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A randomized, double-blind, placebo-controlled trial, which compared the effects of three interventions (weekly chloroquine prophylaxis, daily iron and weekly folic-acid supplementation, and case management of malaria) on congenital malaria, maternal haemoglobin (Hb) and foetal outcome, was conducted among primigravidae resident in Hoima district, Uganda. Among 473 babies examined at birth or within 7 days of birth, 198 (42%) were parasitaemic, the level of parasitaemia in an infant being strongly correlated with those of placental (P< 0.01) and maternal, peripheral parasitaemia (P < 0.01). However, 33 (17%) of the parasitaemic babies were born to mothers who had placental but not peripheral parasitaemia, 22 (11%) to mothers who had peripheral but not placental parasitaemia, and 12 (6%) to mothers with neither peripheral nor placental parasitaemia. Overall, 163 babies were each examined for malarial parasites at birth and 1 month later. Of the 76 (47%) found to have parasitaemia at birth, 37 (23%) appeared aparasitaemic at the 1-month follow-up but 28 (17%) were still parasitaemic at that time. Among the babies born to the mothers who only received case management of malaria during pregnancy, parasitaemia at birth was associated with infant anaemia at birth (i.e. < 140 g Hb/litre; P = 0.03). Infants found to be parasitaemic at the 1-month follow-up had lower mean concentrations of Hb at that time than their aparasitaemic counterparts (P= 0.03). Parasitaemia at birth was not significantly associated with low birthweight, in any of three intervention groups. The intervention given to the mother had no significant effect on the parasitaemia of her baby, either at birth or at the age of 1 month. Congenital malaria per se may have little influence on birthweight but may have an impact on infant anaemia. In conclusion, congenital parasitaemia was not associated with birthweight, but was related to anaemia at birth in infants born to women who had only received active case management during their pregnancies.

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In rural Ugandan communities where onchocerciasis is meso- or hyper-endemic; control of the diseases is now being carried out using a strategy of community-directed programmes for the annual distribution of ivermectin to all persons eligible to take the drug. For these programmes to achieve their annual target coverage of at least 90of the population eligible to take ivermectin; and to continue to sustain themselves for 10-15 years or more; even after external donor funding ceases; it has beenfound essential to replace the initial community-based strategy; imposed from outside; by a community-directed strategy developed by the community members themselves. Furthermore; it is essential for success that full use be made of the traditional social system; which is very strong in all rural communities in Uganda. This system is based on patrilineal kinships and clans; governed by traditional law; and in it women pay an important role. If this system is ignored or by-passed by government health personnel or by the sponsors and promoters of the programme; the communities are likely to fail to reach their targets. When rural communities semi-urbanized. The kinship/ clan system is then weakened; community-directed drug distribution is much more difficult to organize; and coverage targets are not often achieved. This effect is of minor importance in a rural disease; such as onchocerciasis; but is likely to be of greater significance in the control of diseases; such as tuberculosis and lymphatic filariasis; which thrive in urban environments

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Anemia in pregnancy: Plasmodium falciparum infection is an important cause in primigravidae in Hoima District; Western Uganda. Infection with Plasmodium falciparum is a major cause of anaemia in pregnancy; especially in primigravidae. Of 853 primigravidae visiting an antenatal clinic in Hoima district; western Uganda; for the first time; 530(62.1) were found to have P. falciparum parasitaemias and 305 (57.5) of these had atleast 1000 parasites/microliter blood. Plasmodium falciparum parasitaemia was significantly associated with anaemia (relative risk = 0.84; with 95confidence limits = 0.74-0.96; P=0.01). Malarial parasites were detected in 80of the women who had severe anemia (P=0.0008) and hemoglobin concentrations decreased with increasing intensity of infection (P=0.03). Malarial hyper-reactive splenomegaly was associated with high parasite density (P=0.01) and low haemoglobin level (P0.0001). Effective measures aimed at prevention of malaria and anemia in pregnancy; especially in primigravidae; would significantly reduce anemia and its deleterious effects on both the mother and the baby

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Infection with Plasmodium falciparum is a major cause of anaemia in pregnancy, especially in primigravidae. Of 853 primigravidae visiting an antenatal clinic in Hoima district, western Uganda, for the first time, 530 (62.1%) were found to have P. falciparum parasitaemias and 305 (57.5%) of these had at least 1000 parasites/microliter blood. Plasmodium falciparum parasitaemia was significantly associated with anaemia (relative risk = 0.84, with 95% confidence limits = 0.74-0.96; P = 0.01). Malarial parasites were detected in > 80% of the women who had severe anaemia (P = 0.0008) and haemoglobin concentrations decreased with increasing intensity of infection (P = 0.03). Malarial hyper-reactive splenomegaly was associated with high parasite density (P = 0.01) and low haemoglobin level (P < 0.0001). Effective measures aimed at prevention of malaria and anaemia in pregnancy, especially in primigravidae, would significantly reduce anaemia and its deleterious effects on both the mother and the baby.

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Onchocerciasis is far more prevalent and far more of a public-health and socio-economic problem in Uganda than it was thought to be a decade ago. It appears that over a million Ugandans have the disease and nearly two million others live in endemic areas. A few years of annual treatment with Mectizan (ivermectin, MSD) have reduced the community microfilarial load (CMFL) in sentinel villages in Uganda by 52%-100%. The greatest reductions (100%) have been in those villages with the lower CMFL pre-treatment. Assessments at intervals of much less than 1 year should help to show how quickly skin cleared by Mectizan is re-invaded by microfilariae and give an idea of how frequently treatment should be given to produce the greatest benefits. It seems likely that it would be best to give Mectizan at intervals of < 1 year and that such frequent treatment only becomes feasible if Mectizan distribution is community-directed.

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In 1990 a community-based programme of onchocerciasis control, involving the use of ivermectin, was introduced in Uganda. The problems confronting it are discussed and suggestions are made for making it sustainable.

PIP: Onchocerciasis (river blindness) is caused by the filarial worm Onchocerca volvulus, which is transmitted between people by the female blackfly (Simulium). The thread-like adult worms live coiled in nodules beneath the skin. Approximately 85.5 million people in Africa, Latin America, and the Arabian Peninsula are at risk of contracting onchocerciasis. Globally, approximately 18 million people are infected, 1 million are visually impaired, and more than 350,000 have been blinded by infection. Approximately 95% of all infected people live in Africa. About 1.36 million people in Uganda are infected and 1.8 million are at risk. Simulium neavei is responsible for about 85% of onchocerciasis transmission in Uganda. Successful control efforts began in the 1950s consisting of spraying blackfly breeding habitats with DDT were terminated in 1973 due to the imposition of a ban against the use of DDT. Control activities were resumed in 1990 in the form of the launching of the National Onchocerciasis Control Program and the mass distribution of ivermectin. Progress and obstacles in the national, community-based program are described.

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