The focus of disease in Northern Ethiopia is centered around large farms that grow sorghum and sesame, where ecological conditions for transmission (black cotton soil, Acacia trees, Balanites trees) are in abundance. Each year, twice per year, huge numbers of migrants (300,000-500,000) enter the areas to work on these farms. Conditions are extremely tough, with little food, water and shelter provided to the workers by the farms. There are no labour rights and some very harsh conditions and exploitative practices occur often.
The workers come from all over Ethiopia, and from Sudan and Eritrea to seek employment. They arrive for 3-4 months in the period of Mar-Jun to prepare the land (the planting season) and again after the rains in Oct-Jan for harvest. During this time they work and live predominantly outside, in the fields, using the trees as shade and shelter (photo). This is the time when it is assumed that VL transmission is at its highest. The occupational risk of transmission is very high, because the migrant workers have no protection. Trees that are their shelters (pictured) are also the optimum breeding sites for the sandfly vector.
Conventional vector control tools like indoor residual spraying or insecticide treated nets are of no use because migrant workers sleep in the open so they cannot protect themselves using these methods. After completion of their work, the workers return to their places of origin, bringing the disease with them and potentially opening up new foci of disease in villages and towns across the region.
The farms are the site of the KalaCORE entomology research in Ethiopia and the main areas where programme activities are implemented in a series of clinics that serve the area - including the provision of drugs and diagnostic tests, training and clinical mentoring and health education.
There are urgent needs to identify appropriate tools for preventing transmission of VL in seasonal workers, to strengthen health education messages to ensure that they have knowledge of the disease and can take actions to prevent it, and to strengthen advocacy in policy makers and the wider disease control community (i.e. malaria) to address other vector borne diseases (i.e. malaria).