Prevalence and perception of schistosomiasis in irrigated rice field area in Mali

Summary The aim of this work was to assess prevalence and clinic of schistosomiasis as well as the knowledge, attitude and practice (KAP) of populations living in the village of Molodo, a rice irrigated area of Mali. By cross sectional survey with a single passage, we enrolled 346 children aged of 7 to 14 years and 308 parents. The prevalence of Schistosoma haematobium and S. mansoni were respectively 72% and 68%. Micro-hematuria (Sy=86%; Sp=45%), urinary difficulty (Se=828% ; Sp=33%), high frequency of urine (Se=76% ; Sp=31%) and suspubians pain (Se=78% ; Sp=31%) associated with urinary schistosomiasis indicated that these symptoms could be relevant diagnosis signs. Similar observations could be considered as a good sign of diagnosis of intestinal schistosomiasis due to S. mansoni with abdominal pains (Se=75% ; Sp=36%), to have a fancy of stool (Se=75% ; Sp=32%), diarrhea (Se=71% ; Sp=32%), des conjunctival paleness (Se=85,% ; Sp=33%) et de spleen enlargement (Se=71% ; Sp=33%). The transmission patterns of schistosomiasis were not well known by populations, because only 15% of pupils and 38% of parents incriminated the canal and/or the 'fala" (the lake) as genitourinary bilharzias contamination source especially after bathing. The intestinal form was known by 11% of pupils and by 24% of parents. These results show that in spite of schistosomiasis endemic pattern, in this area, populations didn't know well this pathology.

Attitude and practice of health staff in the management of simple malaria in the health district of niono in mali

Summary The aim of this work was to assess the attitude and practice of health staff about malaria. We undertook a cross sectional survey in the district hospital, two community health centers (CSCOM), one private doctor's cabinet and one private nurse's cabinet. We observed the doctors and the nurses during the visit of 261 patients. The most frequent presumption diagnosis was simple malaria without vomiting (53%). Among presumption diagnosis the high frequency of confirmed cases was malaria with vomiting (42%). In the health center, injectable quinine was the most prescribed drug (82%), followed by chloroquine (23%). The injectable quinine was more prescribed by nurses (85%) than doctors (15%) (p=10-6). At the time of follow-up, 98% of patients was cured clinically. Even though malaria was the first reason of visit (99,2%), only one out of ten practitioners checked up temperature of patients. Treatment administered dit not follow guidelines suggested by the national program for malaria control. We thus suggested the training of health staff as well as regular supervision of health centers.

Interleukin-13 in the skin and interferon-gamma in the liver are key players in immune protection in human schistosomiasis

Immunity against schistosomes includes anti-infection immunity, which is mainly active against invading larvae in the skin, and anti-disease immunity, which controls abnormal fibrosis in tissues invaded by schistosome eggs. Anti-infection immunity is T-helper 2 (Th2) cell-dependent and is controlled by a major genetic locus that is located near the Th2 cytokine locus on chromosome 5q31-q33. Mutations in the gene encoding interleukin (IL)-13 that decrease or increase IL-13 production account, at least in part, for that genetic control. In contrast, protection against hepatic fibrosis is dependent on interferon (IFN)-gamma and is controlled by a major genetic locus that is located on 6q23, near the gene encoding the IFN-gamma receptor beta chain. Mutations that modulate IFN-gamma gene transcription are associated with different susceptibility to disease. These data indicate that IL-13 in the skin and IFN-gamma in the liver are key players in protective immunity against schistosomes. These roles relate to the high anti-fibrogenic activities of IFN-gamma and to the unique ability of IL-13 in Th2 priming in the skin and in the mobilization of eosinophils in tissues. The coexistence of strong IFN-gamma and IL-13-mediated immune responses in the same subject may involve the compartmentalization of the anti-schistosome immune response between the skin and the liver.

Identification of the Kna/Knb polymorphism and a method for Knops genotyping

BACKGROUND

DNA mutations resulting in the McCoy and Swain-Langley polymorphisms have been identified on complement receptor 1 (CR1)-a ligand for rosetting of Plasmodium falciparum-infected RBCs. The molecular identification of the Kna/Knb polymorphism was sought to develop a genotyping method for use in the study of the Knops blood group and malaria.

STUDY DESIGN AND METHODS

CR1 deletion constructs were used in inhibition studies of anti-Kna. PCR amplification of Exon 29 was followed by DNA sequencing. A PCR-RFLP was developed with NdeI, BsmI, and MfeI for the detection of Kna/Knb, McCa/McCb, and Sl1/Sl2, respectively. Knops phenotypes were determined with standard serologic techniques.

RESULTS

A total of 310 Malian persons were phenotyped for Kna with 200 (64%) Kn(a+) and 110 (36%) Kn(a-). Many of the Kn(a-) exhibited the Knops-null phenotype, that is, Helgeson. The Kna/b DNA polymorphism was identified as a V1561M mutation with allele frequencies of Kna (V1561) 0.9 and Knb (M1561) 0.1.

CONCLUSION

The high frequency (18%) of Knb in West African persons suggests that it is not solely a Caucasian trait. Furthermore, because of the high incidence of heterozygosity as well as amorphs, accurate Knops typing of donors of African descent is best accomplished by a combination of molecular and serologic techniques.

[Assessment of chloroquine resistance two years after stopping chemoprophylaxis in 0 to 9-year-old children living in a malaria-endemic village of Mali]

This study was carried out in the village of Faladié, Mali located in the malaria-endemic Kati region, two years after routine use of chloroquine prophylaxis was discontinued in children 0 to 9 years old. The main purpose of this study was to assess changes in chloroquine resistance. Two cross-sectional surveys in association with WHO in vivo chloroquine sensitivity testing were conducted, i.e., one in September 2000 and one in December 2002. Findings in 2000 showed that 77.5% of mothers administered chloroquine prophylaxis to their children in compliance with physician orders. The plasmodic index was 62%. The overall level of parasitologic resistance (based on the 1996 WHO in vivo tests) was 80%. The overall therapeutic failure rate was 17.5%. Findings in 2002 demonstrated a plasmodic index of 28%, an overall parasitologic resistance rate of 45% (based on WHO in vivo tests), and an overall therapeutic failure rate of 15%. The diminution of resistance in 2002 may be due to the decrease of drugs pressure and to low exposure of individuals to mosquitoes at the end of transmission season. Althougt these data indicate a 44% drop in chloroquine resistance (P=0.0001), no increase in the clinical efficacy of chloroquine was observed (P=0.05). In view of these results we propose more emphasis on information campaigns to increase public awareness of the need for chemoprophylaxis only for pregnant women, on the promotion of the use of bednets and insecticide-impregnated materials, and on environmental management.

[Epidemiology of malaria in a village of Sudanese savannah area in Mali (Bancoumana). 2. Entomo-parasitological and clinical study ]

We carried out five cross sectional surveys between 1993 and 1994 to assess the epidemiology of malaria in the village of Bancoumana, located in the Sudanese savannah areas of Mali. Each survey included a collection of entomological, clinical, parasitological and immunological data. The study population involved 1600 children from six months to 9 years of age. The main vector was Anopheles gambiae s.l., man bite rate and entomological inoculation rate were maximum respectively in August (peak of the transmission season) and October (end of transmission season). Plasmodium. falciparum was the main parasite species observed. Spleen enlargement rate, parasite rate, gametocyte rate and parasite density varied significantly with age and season. The parasite rate, gametocyte rate and parasite density were significantly low in October 1994 compared with October 1993 while the entomologic parameter did not show any variation over the two years. This reduction of parasitologic index between 1993 and 1994 may be related to an increase of anti-malarial drug use in the population. Our results show that malaria is hyperendemic in the village of Bancoumana.

[Epidemiology of malaria in a village of Sudanese savannah in Mali (Bancoumana). Anti-TRAP and anti-CS humoral immunity response]

Vaccine development research is an important component of malaria control strategies. Thrombospondin related anonymous protein (TRAP) and the circumsporozoite (CS) protein are two antigens of sporozoite surface. Immune response to these two antigens may contribute to the development of anti-sporozoite vaccine. Recent studies suggest that antibodies anti-TRAP may partially block sporozoites penetration in hepatocyte, and thereby reducing malaria morbidity. We carried out a study to assess the seroprevalence of anti-TRAP and anti-CS antibodies and to identify a possible role of these antibodies on malaria morbidity in children 1-9 years old living in a rural hyperendemic village. We performed 5 cross sectional surveys and a longitudinal follow up in 1993 and 1994. During each cross sectional study, children were examined for fever and splenomegaly; all febrile children received thick film examination, and serologic analysis was performed in one third of these, randomly selected. The results show that the seroprevalence of anti-TRAP and anti-CS varied with age and season (p < 0.05). Association between the prevalence of anti-TRAP and splenomegaly was observed during two cross sectional surveys (June and October 1993). The presence of anti-TRAP antibody was associated with Plasmodium falciparum infection at the beginning of the transmission season (June 1993 and July 1994). A negative association between the level of anti-TRAP title and parasitemia was observed (March and October 1994). These findings suggest no clear evidence of the protective role of anti-TRAP antibodies in uncomplicated malaria, possibly due to the limited persistence of these antibodies under natural situations.

[Transmission of schistosomiasis in an urban population and prevalence of intestinal helminthiasis in Bamako, Mali ]

Parasitological, malacological and anthropological studies were performed to assess the prevalence of Schistosoma haematobium and S. mansoni in schoolchildren living in the suburban area of Bamako. A total of 1017 schoolchildren aged 6-14 years were selected in two different areas between September 1997 and December 1999. In Djikoroni, the prevalence of S. haematobium and S. mansoni was 80.7% (339/420) and 22.8% (85/372) respectively. There was no significant difference of prevalence and intensity of infection with S. haematobium between schools, gender and age (p > 0.05), whereas, those of S. mansoni were higher in the vicinity of (+/- 100 m from) major sites where infected Biomphalaria pfeifferi were found (p < 0.001). In Niomirambougou, S. haematobium was prevalent in 46.7% (279/597) and S. mansoni in 28.2% (134/475). Boys and children aged 11-14 years were more infected (p < 0.001). Associated intestinal helminths (Hymenolepis nana, Necator americanus and Ascaris lumbricoides) were relatively scarce (prevalence < 1%). The prevalences of schistosome infected snails intermediate host were relatively high, 49.3% (100/203) in B. pfeifferi, 20.6% (88/138) in B. truncatus and 24.1% (7/29) in B. globosus. We recorded a total of 2514 water contacts about which 1130 in December and 1384 in January. Most of the children, 42.9% (1077/2511) were attracted to water bodies for bathing, swimming and playing, suggesting the lack of recreational facilities in these areas. Developing local control programmes in schools located in the vicinity of water bodies would contribute to break the parasite transmission cycle in Bamako.

[Systematic search for parasites among leprosy patients in Mali]

Practice of multidrug therapy in leprosy (combination Dapsone + Rifampicine + Clofazimine) established since 1981, has significantly reduced the incidence of the disease. However, immunosuppression due to treatment of multi-drugs therapy induced adverse reactions with glucocorticoid and the change in host immune response due to the leprosy itself, might increase the risk of parasitic infections. To test this hypothesis, we carried out a case-control study at the "Institut Marchoux" in Bamako. Stool and urine samples from all patients included in the study were examined for parasites identification. In addition, we performed thick and thin blood film to identify malaria infection and skin biopsy (snip) to detect onchocerciasis. A total of 121 cases of leprosy and 219 controls aged 10-84 years old were included in the study from March 1999 to February 2000. Sixty two percent (n = 121) of cases were treated with glucocorticoid. The prevalence of infection due to Entamoeba coli and Entamoeba histolytica were higher in cases than in controls (p = 0.02). The prevalence of infection due to hookworms was higher in cases than in controls. There was no difference of the infections to the other intestinal parasites. Three cases of cryptosporidiosis and one case of isosporosis were observed in leprosy group vs none in the control group. There was no significant difference between cases and controls with regard to prevalence of Schistosoma haematobium, Trichomonas vaginalis and Onchocera volvulus. The prevalence of Plasmodium falciparum was 4.9% (6/121) in the leprosy case and 7.8% (17/219) in the control group. In conclusion, despite the corticotherapy and immunosuppression due to leprosy, there was no difference in prevalence of pathogenic parasites. Entomoeba coli, Entamoeba histolytica which have significantly higher prevalence among the cases were not pathogen therefore there was no higher risk of severe intestinal parasitosis among the cases of leprosy. Treatment with glycocorticoid in patients with leprosy did not suggest any impact on the prevalence of this parasitic infections. In addition, multidrug therapy did not show any effect on the carriage of Plasmodium falciparum.

[Gastrointestinal manifestations of AIDS in adults in Mali]

Our main objective consists in evaluating the frequency of digestive signs and digestive opportunistic infections in AIDS patients with diarrhea. The prospective study occurred from January 1997 to July 1998 in Bamako hospitals. The patients underwent a clinical examination, blood and stools tests, and sometimes upper digestive endoscopy. Among 434 cases of AIDS, 426 patients (98%) had at least one digestive sign. The main digestive signs were diarrhea (80.1%), abdominal pains (62.2%), vomiting (47.2%) and dysphagea (36.6%). Isospora belli and Cryptosporidium parvum have been pointed up in respectively 9% and 16.3% of examined specimen. Echerichia coli was found in 8.6% of stool cultures and in 2.9% in the case of Salmonella Arizonae. Twenty cases of Kaposi's sarcoma were diagnosed and mycosis was found in 71.9% of patients. In conclusion, digestive change is a constant phenomenon in AIDS patients. Patients survival could be improved by early management, improvement of diagnosis and provisioning of medicines.

[Prevalence and perception of schistosomiasis in a periurban school of Bamako in Mali]

The prevalence of urinary and intestinal schistosomiasis, the knowledge, attitude and practice (KAP) regarding the disease among both the children and their parents were investigated in Djikoroni para, a Suburban area of Bamako. The prevalence of Schistosoma haematobium and S. mansoni were respectively 69.8% and 8.7%. Compared with the girls, the boys were significantly more infected by S. haematobium (p = 5.10(-3)), but no difference between the sexes was observed for S. mansoni (p = 0.36). Interviews indicated that 88% of children and 91% of adults considered micro-haematuria as a pathology, but did not know anything about intestinal schistosomiasis. The low sensitivity of micro-haematuria (56.8%) and of the criterion "abdominal pains" (66.7%) indicated that they couldn't be relevant diagnosis signs. The symptoms and mode of transmission were generally well understood for S. haematobium but not for S. mansoni. The later parasite, its intermediate host and their interactions were unknown. The main man water contacts are bathing and playing in the Woyowayanko and in the Niger river. Inadequate perception of schistosomiasis contributes to maintain schistosomiasis at a high level of prevalence in Djikoroni.

[Treatment of epilepsy in rural areas in Mali]

Epilepsy is a public health problem in Africa due to prevalence and social exclusion. We report a follow-up protocol for epileptic patients treated at home in rural areas of Mali. The objectives were: education for the patient, family, and village leaders in orders to achieve good compliance, uninterrupted supply of generic phenobarbitol, follow-up visits once a month for one year then every two months if good compliance with a country physician with delivery of phenobarbitol in sufficient quantity to reach the next visit, verification of correct drug dosage and use, supervision of treatment effect. After two years, the follow-up visits showed that 57.4% of the patients had been seizure free for at least 24 months (more than 4 monthly seizures before treatment). Rate of seizures decreased in 15.7% of the patients. Results were excellent with no seizures, clear physical, psychic and social improvement (work, married life, school attendance). Very few side effects were observed. There were no cases of poisoning. The management scheme is very cost effective: 1.5 USD per month per patient, including phenobarbitol and implementation. There is a need for anti-epilepsy programs in Africa which should be implemented on the local (rural medicalisation), national and international level ("Epilepsy out of the shadows" campaign).

[Evaluation and treatment of snake bites in Bancoumana village in Mali]

A retrospective study was conducted on the epidemiological patterns and treatment of snakebites in the village of Bancoumana, 60 km south-west from Bamako. We analysed a total of 17 cases (8 males and 9 females). The distribution of snakebite cases by gender and by age showed that among subjects aged 5 to 20 years, boys were more exposed than girls (6 vs. 2), whereas, in those of 21 years and above, females were more frequently bitten than males (7 vs. 2) (p = 0.04). The treatment was mainly based on the use of anti-inflammatories and antibiotics, and sometimes of saline, glucose or anti-tetanic serum. Vitamin K was used in 7 cases and no patient was treated specifically. The success of therapy mostly depended on the shortness of delay between the snakebite occurring and patient referral to the health centre, and the low rate of envenomation. All the patients referred the same day they were bitten were cured, whereas three persons referred to the health centre at D3, D7 and D43 after bite died. The surveillance parameters were oedema, bleeding and vomiting.

Ocular lesions associated with malaria in children in Mali

This study sought to estimate the frequency of ocular complications in malaria and its prognostic value in Mali. A total of 140 children (aged 6 months to 9 years) with severe malaria (105 with cerebral malaria, 35 without neurological complications) were compared with 34 children with mild malaria and 82 children with nonmalarial fever. Ocular lesions were rare in the mild malaria group (5.8%). Retinal hemorrhages occurred in 11.8% of the children in the severe noncerebral malaria group. Cerebral malaria was associated with retinal hemorrhages (22.9%) and retinal edema (10.5%). No association was found between ocular signs such as retinal hemorrhages or retinal edema and mortality. Exudates, papilledema, and the presence of cottonwool spots were associated with an increased risk of death. Coma score and convulsions were significantly associated with death but not with ocular signs. The presence of retinal signs in a child in a malaria-endemic area may signal a case of severe malaria.

Evaluation of an immunofluorescent-antibody test using monoclonal antibodies directed against Enterocytozoon bieneusi and Encephalitozoon intestinalis for diagnosis of intestinal microsporidiosis in Bamako (Mali)

A 2-month study was carried out in Mali to evaluate an immunofluorescent-antibody test (IFAT) using monoclonal probes specific for Enterocytozoon bieneusi or Encephalitozoon intestinalis. Sixty-one human immunodeficiency virus (HIV)-seropositive adult patients and 71 immunocompetent children were enrolled. Microsporidia were detected in stools from 8 of 61 patients (13.1%) seropositive for HIV. A single species, E. bieneusi, was identified. All the children were negative for microsporidia. The sensitivity and specificity of IFAT were 100% compared with those of PCR, which was used as the "gold standard." Moreover, species identification by IFAT was more rapid and less expensive than that by PCR. These results show the suitability of IFAT for detection of microsporidia in developing countries.

Recognition of synthetic polypeptides corresponding to the N- and C-terminal fragments of Plasmodium falciparum Exp-1 by T-cells and plasma from human donors from African endemic areas

The present work describes the recognition of three synthetic polypeptides encompassing the N- and C-terminal regions of the transmembrane Exp-1 protein of the parasite Plasmodium falciparum by plasma and peripheral blood mononuclear cells from naturally exposed individuals living in African endemic areas. The three polypeptides comprise the sequences 23-105, 73-162 and 101-162, and overlap at the transmembrane domain (73-105). Thus, they permitted characterization of the immune response specific to the N- and C-terminal domains in an independent fashion. Two different populations were evaluated, one in the village of Safo in Mali and the other in the villages of Somnaway, Kabortenga and Toussouktenga in Burkina Faso. Antibodies to the sequence 73-162 of Pf Exp-1 were found in 70% of adult Mali donors and in all of the donors tested from Burkina Faso. Strikingly, the N-terminal fragment Pf Exp-1 23-105 was only weakly recognized by a few donors. Evaluation of the T-cell response indicated that the peptide Pf Exp-1 23-105 was more potent than Pf Exp-1 73-162 in inducing a proliferative response. A correlation between peptide-specific interferon-gamma and interleukin-6 production and proliferation to peptide Pf Exp-1 23-105 was observed. Further studies are needed to evaluate this molecule as a vaccine candidate.

A high malaria reinfection rate in children and young adults living under a low entomological inoculation rate in a periurban area of Bamako, Mali

In areas of intense malaria parasite transmission, preliminary studies of the rate of reinfection after curative therapy suggest that small sample size studies of vaccine efficacy are feasible. However, the effect of transmission rate, which may vary considerably between transmission seasons, on reinfection rate has not been assessed in areas of mesoendemicity with seasonal transmission. To address this question, the Plasmodium falciparum reinfection rate after curative therapy was measured in Sotuba, a Malian village with historically low transmission rates, as estimated by the entomological inoculation rate (EIR). The reinfection rate after curative Fansidar (sulfadoxine-pyrimethamine) treatment was 80.7% (88/109). The EIR during the 13-week study period (seasonal transmission) varied between 1 and 4.5 infected bites/person/month. The finding that reinfection rates were high despite low EIRs suggests that a low EIR may be sufficient to support small sample size vaccine efficacy trials in mesoendemic areas.

Treatment with phenobarbital and monitoring of epileptic patients in rural Mali

OBJECTIVE

To assess the efficacy of phenobarbital treatment for epileptic patients in rural Mali.

METHODS

Epileptic patients were treated at home with phenobarbital at daily dosages ranging from 50 mg for children to 200 mg for adults and their condition was monitored. Advice was given to patients, their families, and the village authorities in order to achieve compliance. An uninterrupted supply of generic phenobarbital was provided and a rural physician made two follow-up visits to each village to ensure that the drug was taken in the correct doses. The physician gave information to the population, distributed the phenobarbital in sufficient quantities to cover the periods between visits, and monitored the patients' responses to treatment. During the first year the physician visited the patients every two months. The frequency of visits was subsequently reduced to once every four months.

FINDINGS

In the six months preceding treatment the average rate of seizures among patients exceeded four per month. After a year of treatment, 80.2% of the patients experienced no seizures for at least five months. A total of 15.7% of patients experienced a reduction in seizures. In many cases no further seizures occurred and there were improvements in physical health, mental health and social status. There were very few side-effects and no cases of poisoning were reported. The cost of treatment per patient per year was 7 US dollars for generic phenobarbital and 8.4 US dollars for logistics.

CONCLUSION

Low doses of phenobarbital were very effective against epilepsy. However, there is an urgent need for programmes involving increased numbers of physicians in rural areas and, at the national level, for the inclusion of epilepsy treatment in the activities of health care facilities. Internationally, an epilepsy control programme providing free treatment should be developed.

[Ultrasonographic aspects of urinary schistosomiasis in children of the Dogon plateau and the Niger office; impact of praziquantel treatment]

Urinary bilharziasis is a parasitic infection responsible for vesical, urethral and renal lesions. The authors demonstrate the importance of ambulatory echography on a large scale and describe various echographic lesions. Vesical attacks occurred in 27% of the wall irregularity, 44% of the masses and polyps. Pyelic and urethral abnormalities occurred in 16.6% and 29.9% of cases respectively at the baseline in 1991. These prevalence rates decreased after seven years, in 1998. The authors discuss the utility of chemotherapy with praziquantel and the necessity of a periodical mass treatment in the areas with high bilharziasis endemicity in Mali.

[Reinfection with Schistosoma haematobium and mansoni despite repeated praziquantel office treatment in Niger, Mali]

The dynamics of reinfection by Schistosoma haematobium and Schistosoma mansoni after repeated treatment with praziquantel (40 mg/kg body weight, single dose) was studied in a cohort of schoolchildren living in an endemic area. A total of 214 urine and 220 stool samples were collected and examined at three different times, i.e., February 1989, July 1989 and February 1990. Mass chemotherapy was administered at the beginning of study (February 89). Treatment was repeated in children with positive tests at each subsequent sampling. Prevalence rates were 55.1 p. 100, 3.7 p. 100, and 35.0 p. 100 for Schistosoma haematobium and 62.7 p. 100, 46.3 p. 100 and 73.1 p. 100 for Schistosoma mansoni in February 1989, July 1989 and February 1990 respectively (p < 0.001). From July 1989 to February 1990, reinfection was observed in 84.5 p. 100 of children by Schistosoma haematobium versus 57.8 p. 100 by Schistosoma mansoni. The risk of reinfection by Schistosoma haematobium was higher in children between the ages of 7 and 10 years than in children between the ages of 11 and 15 years (p < 0.001), The incidence of intense Schistosoma haematobium egg excretion rose from 0 p. 100 in July 1989 to 6.0 p. 100 in February 1990. The incidence of intense Schistosoma mansoni excretion in February 1990 was 4.5 p. 100. The reinfection rate at 7 months was over 50 p. 100 for both parasite species despite repeated treatment. This finding demonstrates that additional measures such as proper sanitation and vector control are needed to control human schistosomiasis in irrigated rice paddies.

[Onchocerciasis and epilepsy. Epidemiological survey in Mali]

A door-to-door survey was conducted in 18 villages in Mali with a total of 5,243 inhabitants classified according to the endemicity of onchocerciasis. Each epileptic was matched with two controls. The survey protocol included the following steps in cases and controls: census taking, socioeconomic data, screening for epilepsy, clinical examination, laboratory testing to detect parasites in stools and urine, and snip-test. The crude prevalence of epilepsy was 13.35 per 1,000 (n = 70). Epidemiological study provided a number of valuable demographic insights concerning age at onset, type of seizure activity during seizure and personal and family medical history. A transverse study showed that the prevalence of epilepsy was not significantly higher (p = 9.09) in zones of high endemicity of onchocerciasis (16.1 per 1000) than in zones of low endemicity (10.8 per 1000). Case-control findings showed evidence of onchocerciasis in 22.4 p. 100 of epileptics and 21.7 p. 100 of controls (odds ratio = 1.02 IC 95 p. 100: 0.4-2.19, not significant). Various risk factors including genetic factors and low socio-economic status could explain the trend toward a higher incidence of epilepsy as well as higher morbidity rates in zones of high endemicity of onchocerciasis.

Child malaria treatment practices among mothers in the district of Yanfolila, Sikasso region, Mali

We studied child malaria treatment practices among mothers living in the District of Yanfolila in southern Mali. For sampling, we first chose five of 13 health areas with probability proportional to size. Then villages, compounds and mothers with at least one child aged 1-5 years were randomly chosen. We assessed the spleen size of one 1-5 year-old child of each mother, collected a thick blood film and recorded the body temperature of every child whose mother thought he/she was sick. 399 mothers in 28 villages were interviewed with a structured questionnaire divided into two parts. If the child had had soumaya (a term previously associated with uncomplicated malaria) during the past rainy season, we asked about signs and symptoms, health-seeking behaviour (who the mother consulted first) and treatment. If not, information about knowledge of the disease and treatment to be given was collected. 86% of the mothers interviewed stated that their child had been sick and almost half of them had had soumaya. All mothers named at least one sign by which they recognized the disease. Vomiting, fever and dark urine/yellow eyes/jaundice were the three most common signs mentioned. 75.8% managed their child's disease at home and used both traditional and modern treatment. The most common anti-malarial drug was chloroquine, often given at inappropriate dosage. The sensitivity and specificity of the mothers' diagnosis was poor, although this might be explained by the large percentage of children who had already been treated at the time of the interview. The results of our survey call for prompt educational action for the correct treatment of uncomplicated malaria/soumaya, particularly for mothers and possibly for shopkeepers. The high spleen rate (58.1%) among randomly selected children confirms that malaria is a common disease in this area. Improved case-management at home could only be beneficial.

Toxicity and genotoxicity of antimalarial alkaloid rich extracts derived from Mitragyna inermis O. Kuntze and Nauclea latifolia

The toxicity and the genotoxicity of antimalarial alkaloid rich extracts derived from two plants used in traditional medicine in Mali (Mitragyna inermis (Willd.) O. Kuntze Rubiaceae and Nauclea latifolia (Sm.) Rubiaceae) were evaluated on in vitro and in vivo systems. The results demonstrated that an alkaloid rich extract derived from M. inermis induced a strong inhibition of protein synthesis in mammalian cells but did not exhibit mutagenic or genotoxic activity. An alkaloid rich extract derived from N. latifolia could interact in vitro with DNA of bacteria and mammalian cells, leading to G2-M cell cycle arrest and heritable DNA-damage, as well as inducing in vivo single-strand breaks in liver, kidney and blood cells.

Hemoglobin C associated with protection from severe malaria in the Dogon of Mali, a West African population with a low prevalence of hemoglobin S

The malaria hypothesis proposes a survival advantage for individuals with hemoglobin variants in areas of endemic Plasmodium falciparum malaria. Hemoglobin C (HbC) is a possible example in West Africa, where this hemoglobin has a centric distribution with high frequencies among certain populations including the Dogon ethnic group. To test whether HbC is associated with protection from malaria, we performed a case-control study in the Dogon of Bandiagara, Mali. HbC was present in 68 of 391 (17.4%) of uncomplicated malaria control cases, whereas it was detected in only 3 of 67 cases (4.5%) of severe malaria (odds ratio [OR], 0.22; P =. 01). Further, HbC was present in only 1 of 34 cases (2.9%) with cerebral manifestations, the most common presentation of severe malaria in this population (OR, 0.14; P =.03). Episodes of uncomplicated malaria and parasitemias (4800-205 050/microL) were identified in cases of homozygous HbC (HbCC), which indicates that P falciparum parasites are able to efficiently replicate within HbCC erythrocytes in vivo. These findings suggest that HbC does not protect against infection or uncomplicated malaria but can protect against severe malaria in the Dogon population of Bandiagara, Mali. The data also suggest that the protective effect associated with HbC may be greater than that of HbS in this population.

What does a single determination of malaria parasite density mean? A longitudinal survey in Mali

Temporal variations of blood parasite density were evaluated in a longitudinal study of young, asymptomatic men in a village with endemic malaria in Mali (West Africa). Our main intention was to challenge the value of a single measure of parasite density for the diagnosis of malaria, and to define the level of endemicity in any given area. Parasitaemia and body temperature were recorded three times a day in the wet season (in 39 subjects on 12 days) and in the dry season (in 41 subjects on 13 days). Two thousand nine hundred and fifty seven blood smears (98.5% of the expected number) were examined for malaria parasites. We often found 100-fold or greater variations in parasite density within a 6-hour period during individual follow-up. All infected subjects had frequent negative smears. Although fever was most likely to occur in subjects with a maximum parasite density exceeding 10000 parasites/mm3 (P = 0.009), there was no clear relationship between the timing of these two events. Examples of individual profiles for parasite density and fever are presented. These variations (probably due to a 'sequestration-release' mechanism, which remains to be elucidated) lead us to expect a substantial impact on measurements of endemicity when only a single sample is taken. In this study, the percentage of infected individuals varied between 28.9% and 57.9% during the dry season and between 27.5% and 70.7% during the wet season. The highest rates were observed at midday, and there were significant differences between days. Thus, high parasite density sometimes associated with fever can no longer be considered as the gold standard in the diagnosis of malaria. Other approaches, such as decision-making processes involving clinical, biological and ecological variables must be developed, especially in highly endemic areas where Plasmodium infection is the rule rather than the exception and the possible causes of fever are numerous.

Identification of complement receptor one (CR1) polymorphisms in west Africa

Complement receptor one (CR1) is a ligand for the rosetting of Plasmodium falciparum infected red cells with uninfected cells. Since CR1 exhibits three known polymorphisms, we studied European-Americans (n = 112) and African-Americans (n = 330) and Malians (n = 158) to determine if genetic differences existed in an area endemic for malaria that could offer a survival advantage. The frequencies of Knops blood group phenotypes McC(b+) and Sl(a-) were greatly increased in Africans vs Europeans. Although the frequency of McC(b+) was similar between Africans from the USA or Mali, the Sl(a-) phenotype was significantly higher in Mali (39% vs 65%, respectively). There was an increased frequency of the largest size (250 kD) of CR1 in Mali, but this did not differ significantly from the USA (P = 0.09). Both cohorts of Africans had higher expression of red cell CR1 than European-Americans but this showed little difference between the USA and Mali groups. Thus, the most important CR1 polymorphism relevant to rosetting of malaria infected cells appears to be the Knops blood group.

Antimalarial activity of four plants used in traditional medicine in Mali

Mitragyna inermis (De Willd.) O. Kuntze Rubiaceae, Nauclea latifolia (Sm.) Rubiaceae, Glinus oppositofolius (Linn) Molluginaceae and Trichilia roka (Forsk.) Chiv. Meliaceae were investigated for their in vitro antimalarial activity. Leaves, roots and stem barks were submitted to aqueous, hydromethano and chloroform extractions and antimalarial activity was evaluated by microscopic and flow cytometric analysis. The results present evidence that the alkaloids contained in chloroform extracts and ursolic acid, purified from the hydromethanol extract of M. inermis induced a significant decrease of parasite proliferation. However, aqueous extracts, traditionally used for medication did not show high antimalarial activity. Statistical comparison between microscopic and cytometric analysis demonstrated the validity of this new technique for the screening of active antimalarial compounds isolated from plants.

[Kirikirimasien (epilepsy) in Mali: etiologic and nosologic dimensions]

Epilepsy is a chronic, disabling disease. Its incidence in Mali is 15.6 cases per 1000 people which is four to five times higher than in the West. Kirikirimasien is the name of a local bambaran disease entity similar to epilepsy with respect to both manifestations and course. A field study in a rural, bambaran area was performed to ascertain the nosologic nature of kirikirimasien and determine whether it was comparable with epilepsy in the west. Interviews with patients, family, friends, and healers were carried out and analyzed using qualitative investigative techniques, results showed that diagnosis was established on the basis of symptoms as well as underlying etiology. Nosologic information from the descriptions was correlated with contextual data in order to better understand the nature of the disease. To some extent close attention to pathologic signs associated with this disease such as dreaming and running away, revealed the important sociocultural dimension of kirikirimasien. This dimension is further supported by circumlocutions to avoid pronouncing the name of this disease considered as socially unacceptable. In summary, the sociocultural implications of kirikirimasien are evident in both criteria used for diagnosis and language used to describe it.

Thrombospondin related adhesive protein (TRAP), a potential malaria vaccine candidate

We have investigated whether naturally induced immunity to Plasmodium falciparum thrombospondin related adhesive protein contributes to protection against malaria in humans. We have carried out a case control study in children living in an endemic region of West Africa to reveal associations between PfTRAP seroprevalence and the risk of cerebral malaria. Sera collected from the case and control groups were analysed by ELISA to compare their serum reactivity against PfTRAP, the circumsporozoite protein and the merozoite surface protein 1. Children with uncomplicated malaria had a significantly higher PfTRAP seroprevalence when compared to children with cerebral malaria. The risk of developing cerebral malaria appeared to depend on the reciprocal relationship between sporozoite inoculation rates and humoral immunity against PfTRAP. Our results suggest that naturally induced humoral immunity against PfTRAP contributes to the development of protection against severe malaria. Experimentally induced immunity against TRAP in different rodent models has consistently proven to elicit a high degree of protection against malaria. This together with the functional properties of TRAP and data describing CD4 and CD8 epitopes for PfTRAP indicate that this molecule could increase the protective efficiency of available sporozoite malaria vaccines.

Gametocyte infectivity by direct mosquito feeds in an area of seasonal malaria transmission: implications for Bancoumana, Mali as a transmission-blocking vaccine site

Infectivity of gametocytemic volunteers living in Bancoumana, a village 60 km from Bamako, Mali, was determined by direct feeds of laboratory-reared Anopheles gambiae s. l. Gametocytemic adolescents (10-18 years old) were as infectious to mosquitoes as younger volunteers and appear to be a more suitable population for testing transmission-blocking efficacy as compared with adults (> 18 years old). To begin to validate the membrane-feeding assay, sera collected from these same volunteers were subjected to a standard membrane-feeding assay. The data suggest that areas with intense but seasonal transmission might be feasible sites for testing transmission-blocking vaccines because of the high gametocytemic rates, high mosquito infectivity rates, and lack of pre-existing humoral-mediated transmission-blocking activity. The differences observed between field-based direct mosquito feeds and laboratory-based membrane feeding assays suggests that caution be used in interpreting Phase I study results in which laboratory-based membrane-feeding assays are used as a surrogate for vaccine efficacy.

Use of antimalarial drugs in Mali: policy versus reality

Inappropriate use of antimalarial drugs undermines therapeutic efficacy and promotes the emergence and spread of drug-resistant malaria. Strategies for improving compliance require accurate information about current practices. Here we describe Knowledge-Attitude-Practice surveys conducted among health providers and consumers in two Malian villages, one rural and one periurban. All sanctioned providers limited their first choices of antimalarial drug to those recommended by the national malaria control program and reported using correct dosing regimens. However, the majority of consumers in the two villages chose non-recommended treatments for malaria and reported suboptimal treatment regimens when they did use recommended drugs. Antimalarial drugs were also widely available from unsanctioned sources, often accompanied by erroneous advice on dosing regimens. This study demonstrates that even when the most peripheral health providers are well-trained in correct use of antimalarial drugs, additional measures directly targeting consumers will be required to improve drug use practices.

Natural polymorphism in the thrombospondin-related adhesive protein of Plasmodium falciparum

We have developed a typing system using natural sequence variation in the thrombospondin-related adhesive protein (TRAP) gene of Plasmodium falciparum. This method permits a haplotype to be assigned to any particular TRAP gene. We have applied this method to a hospital-based, case control-study in Mali. Previous sequence variation and conservation in TRAP has been confirmed. Particular TRAP haplotypes can be used as geographic hallmarks. Because of the high level of conflict between characters, we have examined the phylogenetic relationships between parasites using a network approach. Having received patient samples from urban and periurban areas of Bamako, the majority of haplotypes were closely related and distinct from TRAP sequences present in other continents. This suggests that the structure of TRAP can only tolerate a limited number of sequence variations to preserve its function but that this is sufficient to allow the parasite to evade the host's immune system until a long-lived immune response can be maintained. It may also reflect host genetics in that certain variants may escape the host immune response more efficiently than others. For vaccine design, sequences from the major regional variants may need to be considered in the production of effective subunit vaccines.

Resistance to antifolates in Plasmodium falciparum monitored by sequence analysis of dihydropteroate synthetase and dihydrofolate reductase alleles in a large number of field samples of diverse origins

Resistance of Plasmodium falciparum to antifolate chemotherapy is a significant problem where combinations such as Fansidar (pyrimethamine-sulfadoxine; PYR-SDX) are used in the treatment of chloroquine-resistant malaria. Antifolate resistance has been associated with variant sequences of dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS), the targets of PYR and SDX respectively. However, while the nature and distribution of mutations in the dhfr gene are well established, this is not yet the case for dhps. We have thus examined by DNA sequence analysis 141 field samples from several geographical regions with differing Fansidar usage (West and East Africa, the Middle East and Viet Nam) to establish a database of the frequency and repertoire of dhps mutations, which were found in 60% of the samples. We have also simultaneously determined from all samples their dhfr sequences, to better understand the relationship of both types of mutation to Fansidar resistance. Whilst the distribution of mutations was quite different across the regions surveyed, it broadly mirrored our understanding of relative Fansidar usage. In samples taken from individual patients before and after drug treatment, we found an association between the more highly mutated forms of dhps and/or dhfr and parasites that were not cleared by antifolate therapy. We also report a novel mutation in a Pakistani sample at position 16 of DHFR (A16S) that is combined with the familiar C59R mutation, but is wild-type at position 108. This is the first observation in a field sample of a mutant dhfr allele where the 108 codon is unchanged.

A comparison of the incidence of severe malaria in Malian children with normal and C-trait hemoglobin profiles

Although a protective effect against malaria has been demonstrated for several hemoglobin variants, no selective factor is established for the high incidence of HbC in regions of West Africa. Here we report a survey of hemoglobin profiles among children admitted with symptomatic and severe malaria to the Gabriel Touré Hospital in Bamako, Mali, where the frequency of the HbC gene is 8-10%. Children with AC and AA profiles presented with severe malaria at comparable rates, indicating lack of protection by the heterozygous state. Two admitted children, one of whom presented with cerebral malaria, were found to have SC profiles. No CC homozygotes were detected in the study cohort.

[Human intestinal microsporidiosis in Bamako (Mali): the presence of Enterocytozoon bieneusi in HIV seropositive patients]

A study was conducted between 1993 and 1996 in Bamako to determine the rate of occurrence of microsporidia in 88 patients. Most (80%) had chronic diarrhea associated with weight loss and 87.5% were HIV-positive. Intestinal microsporidia were detected in 32% of the patients infected with HIV-1, HIV-2, or coinfected with both strains. Microsporidiosis was also diagnosed in three of the eleven HIV-negative individuals (27%). Microsporidiosis was confirmed by electron microscopy in 6 HIV-positive patients and 1 HIV-negative individual. Enterocytozoon bieneusi was detected in each case. These results suggest that microsporidia are common pathogens in HIV-positive patients in Bamako. Cases of microsporidiosis have been reported for the first time in HIV-2-infected patients. The proportion of women microsporidiosis patients is higher in Mali than in industrialized countries. The presence of microsporidia in HIV-negative patients suggests that these parasites may be an underestimated cause of enteritis in developing countries.

Detection of Loa loa-specific DNA in blood from occult-infected individuals

Accurate and specific diagnosis of human loiasis is of crucial importance in an endemic area where two-thirds of infected individuals are without circulating microfilariae (occult loiasis). By using the polymerase chain reaction (PCR) and specific primers to the repeat 3 region (15r3) of the gene coding for Loa loa 15-kDa polyprotein antigen, DNA was amplified from total blood lysate of occult-infected subjects. A 396-bp DNA fragment was specifically detected. We tested the specificity of this method by qualitative hybridization to PCR products using blood lysates of the following subjects: (1) from Gabon (80 individuals residing in L. loa endemic area where loiasis exists sympatrically with Mansonella perstans); (2) from Togo (12 individuals infected with Onchocerca volvulus and M. perstans); (3) from Tahiti (12 individuals infected with Wuchereria bancrofti); and (4) from Mali (12 individuals infected with O. volvulus and M. perstans). Samples from Gabon included 60 L. loa amicrofilaremics and 20 L. loa occult-infected subjects. Qualitative hybridization carried out at 50 degrees C on PCR products, using a 15r3-specific oligonucleotide probe, revealed hybridization with L. loa-infected samples from Gabon and four samples from Togo after 2 days exposure to the film. The positive samples from Togo were characterized by the use of nested PCR. Three nested PCR products have been sequenced. No differences were observed between the three sequences and they are 99.72% identical to L. loa 15r3. None of bancroftian-infected individuals from Tahiti, nor O. volvulus- and M. perstans-infected individuals from Mali reacted after 1 week's exposure (overexposure) to the film. This allows us to conclude first that our 15r3 PCR assay is specific for L. loa and secondly that L. loa infections occur in Togo. The sensitivity of this 15r3 PCR assay was further investigated with occult patients and field-collected amicrofilaremic samples. We found that 19 of the 20 occult-infected individuals were positive on Southern hybridization, whereas 35/60 amicrofilaremics were positive. These results have shown that the sensitivity of this assay in detecting unequivocal, parasitologically proven occult loiasis was 95%, while the specificity with regard to the sympatric M. perstans was 100%.

Distribution and genetic diversity of Schistosoma haematobium within its bulinid intermediate hosts in Mali

Random amplified polymorphic DNA (RAPD) markers were used to assess distribution and genetic diversity of Schistosoma haematobium populations within their bulinid intermediate hosts in Mali. Naturally infected snails (Bulinus truncatus and B. globosus) were collected at four sites in the Bamako district. S. haematobium cercariae from single snails were used to infect mice and genotypes of the resultant adult worms were characterized using RAPD markers. Diversity indices were calculated at the scale of one snail, both within and among sites. One third of the molluscs harboured multiple miracidial infections (the maximum number equal to five) with slightly overdispersed distributions in three sites and a random distribution at one site. Similarity indices revealed significantly less variation among populations compared with populations, indicative of the absence of distinct S. haematobium populations within the Bamako district. RAPD markers represent an accurate tool for determining genetic diversity and amount of gene flow among parasite populations contained within different individual snails and among intermediate host populations.

Nitazoxanide in the treatment of cryptosporidial diarrhea and other intestinal parasitic infections associated with acquired immunodeficiency syndrome in tropical Africa

Eighteen patients hospitalized with intestinal parasitic infections associated with diarrhea and dehydration completed a study of nitazoxanide in the treatment of Cryptosporidium parvum and other intestinal parasitic infections. Seventeen of the 18 patients were positive for human immunodeficiency virus. Twelve patients were diagnosed with clinical Stage 4 acquired immunodeficiency syndrome (AIDS) according to the 1990 World Health Organization proposed clinical classification system and cryptosporidiosis. Nitazoxanide (500 mg tablets) were administered orally, one tablet twice a day for seven consecutive days. Cryptosporidium parvum oocysts were eradicated or reduced by more than 95% in seven of the 12 Stage 4 AIDS patients who completed the study based upon two post-treatment fecal examinations conducted on days 7 and 14 following the initiation of treatment. The elimination or reduction of C. parvum oocysts was associated with a complete resolution of diarrhea in four of the seven patients. The test drug was also effective against cases of Isospora belli, Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Enterobius vermicularis, Hymenolepis nana, and Dicrocoelium dentriticum. Treatment with nitazoxanide was well tolerated by the patients. There were no abnormalities in blood chemistry or hematology data that were considered to be attributable to nitazoxanide therapy. Transient episodes of vomiting were observed in four patients, all with Stage 4 AIDS and cryptosporidiosis, which resolved spontaneously without discontinuation of treatment and were not considered to be related to administration of nitazoxanide.

Seasonality and malaria in a west African village: does high parasite density predict fever incidence?

In this cohort study, the authors studied the effect of blood malaria parasite density on fever incidence in children in an endemic area with 9 days' follow-up of 1- to 12-year-old children during two time periods: the end of the dry season (May 1993: n = 783) and the end of the rainy season (October 1993: n = 841) in Bougoula, West Africa (region of Sikasso, Mali). The cumulative incidence of fever (temperature > 38.0 degrees C) was 2.0% in the dry season and 8.2% in the rainy season (p < 0.0001). In the rainy season, the risk of fever was increased in children of ages 1-3 years (relative risk (RR) = 2.5, 95% confidence interval (CI) 1.6-4.1); in those with an initial parasitemia > 15,000/microliter (RR = 2.7, 95% CI 1.4-5.4); in children with an enlarged spleen (RR = 2.0, 95% CI 1.2-3.3); or in those with anemia (hematocrit < 30%: RR = 1.8, 95% CI 1.1-2.9). In the dry season, anemia was the only predictor of fever incidence. In the rainy season, the best predictors of fever were, in order, age (< 4 years), enlarged spleen, and high parasite density. Even in the higher risk groups, the cumulative incidence was < 20%. The authors conclude that most children with high parasite density do not develop fever subsequently. The association between parasite density and fever varies according to age and season. Since even high levels of parasite density do not reliably predict fever incidence, parasite density should be considered as just one of a group of indicators that increase the probability of a fever of malarial origin.

Seasonality, malaria, and impact of prophylaxis in a West African village. II. Effect on birthweight

The impact of malaria on low birthweight was investigated in Bougoula village (Sikasso region, Mali). In two successive years, pregnant women were followed until delivery. Phase I (1992) was observational, with 135 complete observations. Phase II (1993) included 126 participants, who were offered malaria prophylaxis with proguanil (200 mg/day) and chloroquine (300 mg/week). The results show that 1) infants of first and second pregnancies had lower birth weights (-382.7 +/- 62.6 g; P < 0.0001) compared with higher rank pregnancies; 2) strong seasonal variation in birthweight was observed in Phase I, with an annual cycle, a nadir in January, and an amplitude of 372.4 g (P = 0.0002); 3) parasitemia measured during pregnancy was associated with lower birthweight in infants from first and second pregnancies, but not from higher parity mothers; and 4) malaria prophylaxis taken for 20 weeks or more in Phase II suppressed the seasonal variation of birthweight and the effect of low parity (+423.4 +/- 118.8 g; P = 0.0004). We conclude that malaria in pregnancy has an important negative impact on birthweight in first and second pregnancies. Prophylaxis with proguanil and chloroquine is an effective prophylaxis when taken for 20 weeks or more.

Seasonality, malaria, and impact of prophylaxis in a West African village I. Effect of anemia in pregnancy

The importance of malaria as a cause of anemia in pregnancy in endemic areas remains controversial. The prevalence of anemia in pregnant women following the dry (May) and the rainy (November) seasons was compared in two successive years in Bougoula village (region of Sikasso, Mali). Phase I (1992) was observational and included 172 pregnant women and 208 controls. In Phase II (1993, 174 pregnant women and 206 controls), malaria prophylaxis with proguanil (200 mg/day) and chloroquine (300 mg/week) was offered to pregnant women. A strong seasonal variation in the prevalence of moderate to severe anemia in pregnant women (hematocrit < 30%) occurred in Phase I (dry season = 8.7%, rainy season = 41.2%). This variation was present only in women of parity lower than five, and paralleled variation in parasitemia. In Phase II, the seasonal variation of anemia was suppressed in women under malaria prophylaxis (presence of antimalarial metabolites in urine), and the overall prevalence of moderate to severe anemia in pregnancy decreased by 55.5% (22.8-74.3%). We conclude that malaria is the major cause of anemia in pregnancy in this region. A high priority should be given to prevention of malaria in pregnancy.

[Protozoan infections and intestinal helminthiasis among the population of a village in the northern Sudan savannah area of Mali (West Africa)]

A cross sectional survey was carried out on intestinal parasites in a rural village located in a Sudan savannah area of Mali in September 1994. This survey was aimed to describe the prevalence of intestinal protozoa and helminths, and to evaluate the possible epidemiological impact of some sociobehavioural factors. A total of 209 stool specimens were examined with 3 methods: fresh stool examination, Kato thick smear technique and a formalin-ether concentration technique in a closed system. Cryptosporidium was also searched following the Ziehl-Neelsen staining and the immunofluorescence method using monoclonal antibody. Microsporidia were investigated by Trichrome staining technique. The concentration technique, as expected, was the more sensitive method: the protozoan cyst rate and the helminth egg rate were 70.3% and 11%, respectively. The low prevalence of intestinal nematodes, unexpected for this area, could be attributed to the improvement in sanitation (traditional WC present in 73.9% of the families), but also to the repeated treatments of the population against onchocercosis with ivermectin since 1992. We found no cases of isosporosis, cryptosporidiosis and microsporidiosis in our study population, neither significant association between socio-behavioural factors and parasitic infections.

Pyrimethamine and proguanil resistance-conferring mutations in Plasmodium falciparum dihydrofolate reductase: polymerase chain reaction methods for surveillance in Africa

As chloroquine resistance spreads across Africa, the dihydrofolate reductase (DHFR) inhibitors pyrimethamine and proguanil are being used as alternative first-line drugs for the treatment and prevention of Plasmodium falciparum malaria. Resistance to these drugs is conferred by point mutations in parasite DHFR. These point mutations can be detected by polymerase chain reaction (PCR) assays, but better methods for sample collection, DNA extraction, and a diagnostic PCR are needed to make these assays useful in malaria-endemic areas. Here we report methods for collecting fingerstick blood onto filter paper strips that are air-dried, then stored and transported at room temperature. Cell lysis and DNA extraction are accomplished by boiling in Chelex-100. We also report a nested PCR technique that has improved sensitivity and specificity. These procedures readily detect mixed infections of parasites with both sensitive and resistant genotypes (confirmed by direct sequencing) and are reliable at parasite densities less than 250/mm3 in field surveys.

[Epidemiology of schistosomiasis in a suburban school area of Bamako (Republic of Mali)]

Epidemiology of schistosomiasis has been assessed in October, 1990 in three primary schools of a suburban district of Bamako: Magnambougou. It was a cross sectional study which was carried out on an hazardous sample of 549 pupils of 7 to 14 years old. The Kato-Katz and urine filtration methods were used to search schistosome eggs. The prevalence rate was 50% (256/512) in Schistosoma haematobium and 5.6% (26/464) in S. mansoni. Children from 11-14 years old were more infected by Schistosoma haematobium (59.4%), than those from 7-10 years old (35.2%) (p < 0.005). Among these children, 26.2% excreted more than 100 eggs per 10 ml of urine. The infection did not varied significantly no matter what the sex is (53.7 and 44.8% respectively in boys and girls) (p = 0.05). According to the residence, pupils living in Magnambougou were more infected (54.9%) than those of others district (31.1%) (p < 0.001). Likewise, S. haematobium infection was more important in A and C schools (64.9 and 73.2% respectively) than in B school (11.2%) (p < 0.001). Two major snails species which are the intermediate hosts of urine schistosomiasis in Mali (Bulinus truncatus and Bulinus globosus) were found in the shelters: however, B. truncatus was only infected in 13.1% (19/145). Contamination was local and "ruralization" activities (particularly gardening) seemed to be the most important displaying factor.

Analysis of the human antibody response to thrombospondin-related anonymous protein of Plasmodium falciparum

Thrombospondin-related anonymous protein (TRAP) of the malaria parasite Plasmodium falciparum shares two sequence motifs with other proteins which possess adhesive properties. Recently, findings indicate that TRAP is an antigen which contributes to antisporozoite immunity. We have cloned and expressed the TRAP coding sequences in Escherichia coli to investigate the human humoral immune response against this protein in a region of malaria endemicity of West Africa characterized by a seasonal transmission. Our results show that antibodies against TRAP are present in infected individuals. The anti-TRAP antibodies were analyzed in both a longitudinal and a prospective study. The longitudinal analysis shows seasonal fluctuations of the levels of specific antibodies as well as age-dependent quantitative differences. The immune response is long-lived in most of the adults and some of the older children but short-lived in young children. More importantly, the prospective analysis suggests that the presence of anti-TRAP antibodies in older children before the beginning of malaria transmission correlates with the subsequent control of parasite densities.