First phase of baseline data collection completed in Mali

The first phase of the Mali baseline data collection (BDC) took place in March and April 2004.

The first phase of the Mali baseline data collection (BDC) took place in March and April 2004. The team was composed of Ministry of Health staff (led by Dr Robert Dembele, Coordinator of the Programme National de Lutte contre les Schistosomiases, by Dr Moussa Sacko, Dr Aly Landoure and Dr Godefroy Coulibaly, epidemiologists of the Institut National de Recherche en Santé Publique, and by Dr Adama Keita, ultrasound specialist) and accompanied by Dr Albis-Francesco Gabrielli from SCI.

During the first half of the BDC, 537 children were enrolled from five village schools along River Niger, in an area highly endemic for urinary schistosomiasis, located in the Segou region. Information recorded on each child included age, sex, anthropometric measurements (such as height, weight, sternum and umbilical circumference), a clinical and an ultrasound examination. Biological samples collected included blood for anaemia assessment, urine and faeces for parasitological examination for schistosomes and intestinal helminths. Each child enrolled in the survey was treated with the appropriate dose of Praziquantel and Albendazole, and any potential side effects were monitored.

Above: Urine samples with gross haematuria (left) and Ultrasound scan of the bladder showing masses protruding into the organ's lumen (right)

In each of the five schools the parasitological prevalence of Schistosoma haematobium infection was higher than 98%; the mean prevalence of microhaematuria (assessed by Hemastix©) was 85.9%. 50.4% of the sample had urinary system pathology detectable by Ultrasound, and lesions were almost uniformly spread all over the sample age groups, from 7 to 14 years old. The ultrasound image presented here is particularly striking of the sequelae often associated with S. haematobium infection.

Data collection has subsequently continued in other areas of the Segou region, namely the Office du Niger-Macina area and the San area, and results will be reported shortly. Segou is the first of five regions of Mali where the Malian Ministry of Health will collect data on prevalence, intensity and morbidity due to urinary and intestinal schistosomiasis and soil-transmitted helminths among school-age children.

Transmission of schistosomiasis along River Niger in Mali

River Niger near Segou. Disease epidemiology in this area is linked with the seasonal overflowing of the great river.

The epidemiological-ecological pattern of disease transmission in villages situated along the River Niger in the Segou area is strictly linked to seasonal overflowing of the river. During the rainy season (the so-called hivernage, which starts in June, reaches its peak in August-September, and starts to decline in October to end up in November) the river overflows and the water fills a plain about 500m-wide between its banks and the villages, which are usually slightly higher (ca. 5m) than the surrounding plains, or are protected by small dams.

The flooded plains, where many temporary ponds are created by the overflowing of the river, and many others by the rain itself (that also creates small rivers pointing towards the River Niger) are the major foci of transmission, because snails thrive there and many human water contact activities are linked to them, both occupational (e.g. agricultural and fishing) and recreational (e.g. playing).

Collective fishing in the Office du Niger area. Many of the small natural water bodies are the sites of very intense water contact and potential disease transmission.

During the dry season many small ponds are left behind by the river as it retreats to its bed. Many of them gradually dry up (temporary ponds or “mares temporaires”), but many others persist all year round (permanent ponds or “mares permanentes”). These can sustain snails and therefore disease transmission during the whole year, as they are frequently used for irrigation purposes (especially horticulture). Market gardening and fishing are the main sources of income, but both are responsible for behavioural patterns that highly increase the risk of transmission. Schistosomiasis is in this case an “occupational disease” for all age-groups, since also very young children are employed for fishing and water collection and transport.