Taenia solium metacestode preparation in rural areas of sub-Saharan Africa: a source for diagnosis and research on cysticercosis.

BACKGROUND: Taenia solium metacestodes/cysts obtained from pig carcasses constitute a primary source for diagnostic tools used for the detection of human cysticercosis. Data on T. solium cyst preparation in Africa is still scarce but required to establish independent reference laboratories. OBJECTIVES: The aim of the present study is a) to present the likely yield of T. solium cyst material by the use of two different preparation methods in the field and b) to investigate its suitability for immunodiagnosis of human cysticercosis. METHODS: In Zambia, Uganda and Tanzania 670 pigs were screened for T. solium infection. Cysts were prepared by 'shaking method' and 'washing method'. Generated crude antigens were applied in a standard western blot assay. RESULTS: 46 out of 670 pigs (6.9%) were found positive for T. solium (Zambia: 12/367, 3.3%; Uganda: 11/217, 5.1%; Tanzania 23/86, 26.7%). Mean values of 77.7 ml whole cysts, 61.8 ml scolices/membranes and 10.9 ml cyst fluid were obtained per pig. Suitability of collected material for the use as crude antigen and molecular diagnostic techniques was demonstrated. CONCLUSION: This study clearly shows that T. solium cyst preparation in African settings by simple field methods constitutes an effective way to obtain high quality material as source for diagnostic tools and research purposes.

Risk factors for anaemia in schoolchildren in Tanga Region, Tanzania.

Anaemia is one of the major public health problems affecting more than half of school children along the coast in Tanzania. Due to the multiplicity of its causes it sometimes becomes difficult to find appropriate intervention measures. In order to assist schools in implementing appropriate public health measures for anaemia in Tanga Region of Tanzania risk factors were investigated in school children. A total of 845 schoolchildren age 7-14 years were randomly selected in a cross-sectional survey conducted in 20 randomly selected schools for inclusion in the investigations. Socio-economic, environmental and biological data were collected, as well as academic information, health care and feeding practices. Diagnosis of anaemia was based on haemoglobin concentration below 115 g/L determined by HemoCue meter. Serum Retinol was determined by High performance liquid chromatography and serum ferritin by an Enzyme linked immunosorbent assay. Urine from each child was tested for blood using a haematest reagent strip and those testing positive were examined microscopically by filtration method for Schistosoma haematobium ova. A faecal sample collected from them was also examined microscopically for ova and larvae of intestinal worms. To analyse variables associated with anaemia a stepwise multiple regression model was used. The prevalence of anaemia was 79.6%. Micronutrient deficiencies were highly prevalent. Iron deficiency (SF <20 microg/dl) was affecting 33%, vitamin A deficiency (SR < 20 microg/dL) 31.9% and 25% of the children had mild iodine deficiency (UIE < 20 microg/L). Intestinal helminths were also highly prevalent; 68% of children had hookworm and 54% had urinary schistosomiasis. Inadequate diet was a feature in >50% of children. About 10% of households had no latrines and multiple infection rank score was high especially in older age children. The risk of having anaemia was two times higher in children with iron deficiency (RR=2.1) and 49% higher in those with vitamin A deficiency. These deficiencies correlated significantly with the anaemia (P<0.05). Vitamin A deficiency and infections with hookworm and schistosomiasis were the most significant factors predicting for anaemia (r=0.318 and r2=0.101). We therefore conclude that high prevalence of infections and nutritional deficiencies are important risk factors for anaemia in this community. The high attributable fractions for hookworm, schistosomiasis, iron deficiency and vitamin A confirms that these are significant risk factors to be considered when designing public health measures for anaemia prevention in this community.

Anthelmintic treatment improves the hemoglobin and serum ferritin concentrations of Tanzanian schoolchildren.

To investigate the relationships between helminth infections and iron status among school-aged children, 1,115 Tanzanian children in grades 2 through 5 were randomly assigned to treatment or control groups. The children in the treatment group were screened for infection with Schistosoma haematobium and hookworm at baseline, 3 months, and 15 months; infected children were given albendazole against hookworm and praziquantel against schistosomiasis. The control group received a placebo and did not undergo parasitological screening until 15 months after the baseline. Hematological variables were compared between the treatment and control groups. The main results were, first, that the hemoglobin concentration significantly improved after treatment for hookworm (p < .001) by 9.3 g/L in children treated for hookworm only and by 8.8 g/L in children treated for hookworm and schistosomiasis. The ferritin concentration also improved in children treated for schistosomiasis (p = .001) or hookworm (p = .019). Second, a longitudinal analysis of the data from the children in the control group showed that hookworm and schistosomiasis loads were negatively associated with hemoglobin and ferritin concentrations. Moreover, ferritin concentrations increased as C-reactive protein levels increased. Overall, the results showed that anthelmintic treatment is a useful tool for reducing anemia in areas with high hookworm and schistosomiasis endemicity. The empirical relationship between ferritin and C-reactive protein indicated that simple procedures for adjusting cutoff points for the use of ferritin as an indicator of low iron stores were unlikely to be useful in this population.

Schistosomiasis, helminth infection and health education in Tanzania: achieving behaviour change in primary schools.

Over a period of one school year a study was carried out into the feasibility and effectiveness of introducing active teaching methods into primary schools in Tanzania with a view to enhancing health education. The Lushoto Enhanced Health Education Project had as a focus personal hygiene with reference to the control of schistosomiasis and helminth infections. When a randomly selected group of children were compared with a comparison group there was evidence of changes in both knowledge and health-seeking behaviour. The passing of messages from children to the community met with mixed results. The observed changes were still evident over 1 year after the project had ended.

Heavy schistosomiasis associated with poor short-term memory and slower reaction times in Tanzanian schoolchildren.

Cross-sectional studies of the relationship between helminth infection and cognitive function can be informative in ways that treatment studies cannot. However, interpretation of results of many previous studies has been complicated by the failure to control for many potentially confounding variables. We gave Tanzanian schoolchildren aged 9-14 a battery of 11 cognitive and three educational tests and assessed their level of helminth infection. We also took measurements of an extensive range of potentially confounding or mediating factors such as socioeconomic and educational factors, anthropometric and other biomedical measures. A total of 272 children were moderately or heavily infected with Schistosoma haematobium, hookworm or both helminth species and 117 were uninfected with either species. Multiple regression analyses, controlling for all confounding and mediating variables, revealed that children with a heavy S. haematobium infection had significantly lower scores than uninfected children on two tests of verbal short-term memory and two reaction time tasks. In one of these tests the effect was greatest for children with poor nutritional status. There was no association between infection and educational achievement, nor between moderate infection with either species of helminth and performance on the cognitive tests. We conclude that children with heavy worm burdens and poor nutritional status are most likely to suffer cognitive impairment, and the domains of verbal short-term memory and speed of information processing are those most likely to be affected.

Predicting the distribution of urinary schistosomiasis in Tanzania using satellite sensor data.

In this paper, remotely sensed (RS) satellite sensor environmental data, using logistic regression, are used to develop prediction maps of the probability of having infection prevalence exceeding 50%, and warranting mass treatment according to World Health Organization (WHO) guidelines. The model was developed using data from one area of coastal Tanzania and validated with independent data from different areas of the country. Receiver operating characteristic (ROC) analysis was used to evaluate the model's predictive performance. The model allows reasonable discrimination between high and low prevalence schools, at least within those geographical areas in which they were originally developed, and performs reasonably well in other coastal areas, but performs poorly by comparison in the Great Lakes area of Tanzania. These results may be explained by reference to an ecological zone map based on RS-derived environmental data. This map suggests that areas where the model reliably predicts a high prevalence of schistosomiasis fall within the same ecological zone, which has common intermediate-host snail species responsible for transmission. By contrast, the model's performance is poor near Lake Victoria, which is in a different ecological zone with different snail species. The ecological map can potentially define a template for those areas where existing models can be applied, and highlight areas where further data and models are required. The developed model was then used to provide estimates of the number of schoolchildren at risk of high prevalence and associated programme costs.

Community perception of school-based delivery of anthelmintics in Ghana and Tanzania.

This paper presents the results of an evaluation of community perception of two large-scale, government-run, school-based health programmes delivering anthelmintic drugs to primary school children, in Ghana (80 442 children in 577 schools) and Tanzania (110 000 children in 352 schools). Most teachers (96% in Ghana and 98% in Tanzania) were positive about their role in the programme, including administration of anthelmintic drugs, and parents and children fully accepted their taking on this role. The benefits of the programme were apparent to teachers, parents and children in terms of improved health and well-being of the children. Over 90% of parents in both Ghana and Tanzania indicated a willingness to pay for the continuation of drug treatment. The evaluation also highlighted areas that are critical to programme effectiveness, such as communication between schools and parents, the issue of collaboration between the health and education sectors, parents' perception of the importance of helminth infection as a serious and chronic health problem (compared with more acute and life threatening illnesses such as malaria), and who should pay for treatment of side-effects.

Evaluation of efficacy of school-based anthelmintic treatments against anaemia in children in the United Republic of Tanzania.

OBJECTIVE: To determine the impact of deworming on anaemia as part of a large-scale school-based anthelmintic treatment programme in the Tanga Region of the United Republic of Tanzania. METHODS: Both the reduction in the prevalence of anaemia and the cost per case prevented were taken into consideration. Cross-sectional studies involved parasitological examination and anaemia evaluation before and at 10 months and 15 months after schoolchildren were dewormed. FINDINGS: Baseline studies indicated that the prevalence of anaemia (haemoglobin < 110 g/l) was high (54%) among schoolchildren, particularly those with high intensities of hookworm and schistosomiasis. Attributable fraction analysis suggested that hookworm and schistosomiasis were responsible for 6% and 15% of anaemia cases, respectively. Fifteen months after deworming with albendazole and praziquantel the prevalence of anaemia was reduced by a quarter and that of moderate-to-severe anaemia (haemoglobin <90 g/l) was reduced by nearly a half. The delivery of these anthelmintics through the school system was achieved at the relatively low cost of US$ 1 per treated child. The cost per anaemia case prevented by deworming schoolchildren was in the range US$ 6-8, depending on the haemoglobin threshold used. CONCLUSIONS: The results suggested that deworming programmes should be included in public health strategies for the control of anaemia in schoolchildren where there are high prevalences of hookworm and schistosomiasis.

The effects of sex and age of responders on the reliability of self-diagnosed infection: a study of self-reported urinary schistosomiasis in Tanzanian school children.

Self-reported schistosomiasis has been proven to be a reliable estimation of the prevalence of infection in school children. For the first time, this paper presents an investigation into the use of self-reported schistosomiasis to estimate the prevalence of urinary schistosomiasis, due to Schistosoma haematobium, in school children with particular emphasis on whether the age and sex of respondents influences the reliability of diagnosis. It is shown first, that the prevalence and intensity of infection vary with sex; infection in boys is always more prevalent and more intense than in girls of the same age and second, that age and sex influence the reliability of self-reported schistosomiasis as a diagnostic method. Age and sex are factors that should be considered when implementing control measures in endemic areas.

Anaemia in schoolchildren in eight countries in Africa and Asia.

OBJECTIVE: To report on the haemoglobin concentrations and prevalence of anaemia in schoolchildren in eight countries in Africa and Asia. DESIGN: Blood samples were collected during surveys of the health of schoolchildren as a part of programmes to develop school-based health services. SETTING: Rural schools in Ghana, Indonesia, Kenya, Malawi, Mali, Mozambique, Tanzania and Vietnam. SUBJECTS: Nearly 14 000 children enrolled in basic education in three age ranges (7-11 years, 12-14 years and > or =15 years) which reflect the new UNICEF/WHO thresholds to define anaemia. RESULTS: Anaemia was found to be a severe public health problem (defined as >40% anaemic) in five African countries for children aged 7-11 years and in four of the same countries for children aged 12-14 years. Anaemia was not a public health problem in the children studied in the two Asian countries. More boys than girls were anaemic, and children who enrolled late in school were more likely to be anaemic than children who enrolled closer to the correct age. The implications of the four new thresholds defining anaemia for school-age children are examined. CONCLUSIONS: Anaemia is a significant problem in schoolchildren in sub-Saharan Africa. School-based health services which provide treatments for simple conditions that cause blood loss, such as worms, followed by multiple micronutrient supplements including iron, have the potential to provide relief from a large burden of anaemia.

The impact of weekly iron supplementation on the iron status and growth of adolescent girls in Tanzania.

We evaluated the effect of weekly doses of 400 mg of ferrous sulphate for 4 months on the iron status of adolescent girls in a controlled trial in Tanga, Tanzania. Supplementation led to a significantly greater increase in serum ferritin compared with the control group (+ 15.6 microg/l vs. 8.6 microg/l) (P = 0.002) but there was no significant difference in change in haemoglobin. Children given iron showed a significantly greater weight gain than controls (+ 2.4 kg vs. + 1.4 kg) (P = 0.03). Weekly iron supplementation may be an effective means of increasing iron stores and growth in children vulnerable to iron deficiency.

The health of enrolled and non enrolled children of school age in Tanga, Tanzania.

The health of 227 children enrolled at primary school was compared with that of 214 non enrolled children living in rural Tanga, Tanzania. No consistent difference was observed with respect to prevalence and intensity of parasitic infection (hookworm, T. trichiura, A. lumbricoides, S. haematobium and P. falciparum). Since enrolled children were as commonly and as heavily infected as non enrolled children, treatment of enrolled children would be effective in reducing transmission throughout the total population. Non enrolled children were more stunted (P=0.0001) and wasted (P=0.0001) than enrolled children and also tended to be more anaemic (P=0.080) showing that poor nutrition is not only associated with delayed enrolment but continues to be associated with non enrolment throughout the school age years. Given that treatment has the greatest impact on the most malnourished children, additional measures to extend treatment to non enrolled children would be justified.

The impact of population level deworming on the haemoglobin levels of schoolchildren in Tanga, Tanzania.

The impact of albendazole (400 mg) and praziquantel (40 mg/kg body weight) treatment of schoolchildren was compared with placebo according to the presence of anaemia (haemoglobin concentration < 11. 0 g/dl) and heavy (> 5000 epg) or light (< 5000 epg) hookworm egg load. The study was conducted in rural Tanga. Medication was administered in September 1994 and children were followed-up in January 1995. Overall, anthelminthic treatment reduced the fall in haemoglobin concentration compared with that observed in the placebo group (- 0.11 g/dl vs. - 0.35 g/dl; P = 0.02). Anthelminthic treatment was of greatest benefit to the 9% of children with both anaemia and heavy hookworm egg load (+ 0.67 g/dl vs. - 0.67 g/dl) and was also of significant benefit to the 38% of children with anaemia and light hookworm egg load (+ 0.07 g/dl vs. - 0.21 g/dl). It was of no significant benefit to children who were not anaemic. This study suggests that single-dose anthelminthic treatment distributed in schools in this area achieves haematological benefits in nearly half of children infected with S. haematobium and geohelminths (37% of total population).

Bancroftian filariasis on Pemba Island, Zanzibar, Tanzania: an update on the status in urban and semi-urban communities.

Cross-sectional clinical, parasitological and entomological surveys for bancroftian filariasis were conducted in Konde, Chake Chake and Kengeja, three urban and semiurban communities on Pemba Island, and the results were compared with similar surveys done 15 years earlier. The overall prevalences of clinical manifestations among males aged 15 years or more (n = 614) was remarkably similar to those recorded 15 years earlier: elephantiasis 1.4% in 1975 and 1.1% in 1990; hydrocele, 22.4% and 21.8%, respectively. However, when the communities were compared individually, there was a reduction in the hydrocele prevalence in Konde from 22.4% to 11.5% and an increase in Kengeja from 27.0% to 35.5%. The overall microfilarial prevalence found during night blood surveys of all individuals aged 1 year or more (n = 2687) was 9.7%, compared to 14.2% recorded in 1975. The reduction was most pronounced in Konde. Of 1052 female mosquitoes caught with CDC light traps, 95% were Culex quinquefasciatus and 5% Anopheles gambiae s.l. Infective larvae of Wuchereria bancrofti were found only in the former. The filariasis situation in urban and semiurban communities on Pemba Island appears not to have changed considerably over the last 15 years.

Alternatives to bodyweight for estimating the dose of praziquantel needed to treat schistosomiasis.

Data on age, height and mid upper-arm circumference (MUAC) from nearly 6000 schoolchildren in Ghana, Tanzania and Malawi (not MUAC) were used to examine their power to predict bodyweight and thus the dosage of praziquantel required to treat schistosomiasis. Height was found to provide a simple and reasonably accurate estimate of weight, and about 75% of children would have been given a dosage of praziquantel within the range normally given using bodyweight at a dosage of 40 mg/kg bodyweight. The upper and lower ranges in dosage did not exceed dosages of praziquantel which have been used before or are currently recommended to treat schistosomiasis. A pole marked with the number of tablets could thus be used as a simple way to determine the dose of praziquantel to treat children in school-based health programmes.

The reliability of self-reported blood in urine and schistosomiasis as indicators of Schistosoma haematobium infection in school children: a study in Muheza District, Tanzania.

The use of self-reported blood in urine and schistosomiasis by school children was investigated as a tool to estimate the prevalence of infection with Schistosoma haematobium and to identify infected individuals. A general questionnaire about common health problems, including questions about blood in urine and schistosomiasis, was administered by teachers to 25443 children in 137 primary schools in Muheza District, Tanzania. The prevalence of reported schistosomiasis was calculated for each school and used to select 15 schools across a range in prevalence. All children in the 15 schools (n = 2370) were interviewed again by a nurse and gave a urine sample which was subjected to a quantitative microscopical examination for the eggs of S. haematobium by filtration. The prevalence of reported schistosomiasis by the interview in the 15 schools correlated strongly with the prevalence reported during the questionnaire survey. The prevalence of reported schistosomiasis in the interview was strongly correlated with the prevalence of infection determined by microscopy and consistently under-estimated the latter by around 20% across a range in prevalence from 22% to 93%. The sensitivity of diagnosis by an interview increased almost linearly with the prevalence of infection, so that when the prevalence was high, more infected children reported schistosomiasis. The percentage of children who were correct in their self-diagnosis was independent of the prevalence of infection and of the mean concentration of eggs in urine, and averaged 75%. These findings suggest that self-reported schistosomiasis is a useful method to estimate the prevalence of infection in schools and might be used to identify infected individuals.

Potential for diagnosis of intestinal nematode infections through antibody detection in saliva.

The present study was the first to investigate the potential of saliva in community diagnosis of the major human intestinal nematode infections, Trichuris trichiura, Ascaris lumbricoides, and the hookworms. Immunoglobulin G (IgG) antibodies specific to parasite antigens were quantified in saliva samples of 187 individuals (all ages) from a St Lucian community, and 120 school-aged children from Tanga region, Tanzania, and relationships with current infection status (determined by numbers of parasite eggs in stool) were examined. For T. trichiura infection, the age relationships of parasite-specific salivary IgG antibodies mirrored those of infection intensity at the community level. Within both areas, children with current T. trichiura infection exhibited significantly higher anti-T. trichiura salivary IgG responses than uninfected children. Similar trends were apparent for A. lumbricoides and hookworm infections, though not to a level of statistical significance. Comparison of mean T. trichiura infection levels and antibody responses in age-matched children from St Lucia and Tanzania suggested that measurement of parasite-specific salivary IgG may have potential as a marker of transmission intensity at the community level.

School health programmes.

PIP: In sub-Saharan Africa, the population of school-age children is expected to increase by 205 million during the 1990s. Mortality is low among this group, but morbidity commonly affects physical growth, school attendance, and ability to learn. Given that there are more schools than clinics and that schools collect children in one place, schools are an ideal place for health education. Training of teachers as health educators will require cooperation between ministries of health and education. Some health problems can be treated in schools. These include the presence of intestinal worms (which is assumed to warrant mass treatment if 50% or more of the smears of 30 children are infected), schistosomiasis (in which mass treatment is warranted if 30% of children report blood in their urine), and micronutrient deficiencies. Teachers can be trained to determine disease prevalence and deficiency levels and to administer treatment. Body height can be used to determine the correct dosage of praziquantel to treat schistosomes. Teachers can also be trained to detect poor vision and growth faltering and can administer iodine and vitamin A to their students as well as iron supplementation to adolescent girls. One problem with this school-based approach is that it misses children who are not enrolled in schools. School health programs, however, can achieve good coverage in a very cost-effective manner, as can be seen by the experiences of Ghana and Tanzania, where praziquantel and albendazole are administered together by teachers under the supervision of local health personnel. The low cost of all of the drugs needed to combat these diseases and deficiencies combined with the existence of the delivery system has led to identification of school health services as one of the six most cost-effective public health interventions.^ieng

Clinical efficacy and pharmacokinetics of artemisinin monotherapy and in combination with mefloquine in patients with falciparum malaria.

1. The aim of this study was to assess the pharmacokinetics, clinical efficacy and safety of artemisinin alone and in combination with mefloquine. 2. Thirty-eight adults with symptomatic Plasmodium falciparum malaria were randomly assigned to receive either artemisinin (500 mg single dose followed by another 500 mg on day 1 and then 250 mg twice daily for 4 days) or artemisinin (500 mg single dose followed by 750 mg on day 1 and then 250 mg three times daily for one more day) in co-administration with mefloquine (250 mg three times daily for the first day). All drug administration was by the oral route. Patients were hospitalized at the Kibaha Designated District Hospital, Kibaha, Tanzania, for 6 days and a follow up for 3 weeks was performed. 3. Treatment with the artemisinin/mefloquine combination resulted in a shorter parasite clearance time (PCT) of 24 (22, 27; 95% confidence interval) h vs 31 (27, 36) h and fever subsidence time (FST) of 14 (12, 16) h vs 20 (18, 23) h compared with artemisinin monotherapy. The 95% CI for the difference of the PCT and FST were 1.7, 12 and 3, 10, respectively. Parasites were detected in 7 out of 17 patients (41%) receiving artemisinin monotherapy at the 3rd and 4th week follow up visits. No parasites were detected after the combination therapy. 4. The maximum plasma concentrations (Cmax) were similar after artemisinin monotherapy (615.4 +/- 387.0 ng ml-1) and in combination with mefloquine (851.8 +/- 523.6 ng ml-1). Elimination half-lives (t1/2) were also identical at 2.2 +/- 0.6 h and 2.5 +/- 0.7 h, respectively. However, the AUC values were higher (P < 0.05) after combination therapy (3252 +/- 1873 ng ml-1 h) than after monotherapy (2234 +/- 1502 ng ml-1 h). The oral clearance values were lower (P < 0.05) after combination therapy (195.4 +/- 86.9 l h-1) than after monotherapy (314.3 +/- 189.4 l h-1). PCT and FST normalized to initial parasitaemia correlated with AUC(0, t) (rs = 0.56, P = 0.02, rs = 0.58, P = 0.01, respectively) and with Cmax (rs = 0.62, P = 0.01, rs = 0.68, P = 0.005, respectively) in the artemisinin monotherapy only. 5. One patient on the combination therapy developed a psychiatric condition and two patients on the monotherapy developed skin itch.