The public health significance of Trichuris trichiura

An estimated 1049 million persons harbour T. trichiura, including 114 milli on preschool-age children and 233 million school-age children. The prevalen ce of T. trichiura is high and may reach 95 % in children in many parts of the world where protein energy malnutrition and anaemias are also prevalent and access to medical care and educational opportunities is often limited. The Trichuris dysentery syndrome (TDS) associated with heavy T. trichiura, which includes chronic dysentery, rectal prolapse, anaemia, poor growth, a nd clubbing of the fingers constitutes all important public health problem, as do lighter but still heavy infections, even if not strictly TDS, especi ally in children. The profound growth stunting in TDS can be reversed by re peated treatment for the infection and, initially, oral iron. However findi ngs from Jamaica strongly suggest that the significant developmental and co gnitive deficits seen art: unlikely to disappear without increasing the pos itive psychological stimulation in the child's environment. The severe stun ting in TDS now appears likely to be a reaction at least in part to a chron ic inflammatory response and concomitant decreases in plasma insulin-like g rowth factor-1 (IGF-1), increases in tumor necrosis factor-alpha (TNF-alpha ) in the lamina propria of the colonic mucosa and peripheral blood (which l ikely decrease appetite and intake of all nutrients) and a decrease in coll agen sythesis. Improvements in cognitive performance have been found after treatment for relatively heavy infections (without chronic dysentery) in sc hool-going children; it is unclear precisely how much T. trichiura interfer es with children's ability to access educational opportunities, but treatme nt of infections whenever possible is obviously sensible. The blued loss th at can occur in T. trichiura infection is likely to contribute to anaemia, particularly if the child also harbours hookworm, malaria and/or has a low intake of dietary iron. Community control is important, particularly for th e individuals within a population who harbour heavy worm burdens; this mean s children, with special attention to girls who will experience increased i ron requirements: and blood loss due to menstruation, pregnancies, and lact ation. Mebendazole and albendazole, both of which are on the WHO Essential Drugs List, are very effective against T. trichiura; multiple doses are nee ded to attain complete parasitological cure in all cases. However the goal of control programmes in endemic areas is morbidity reduction, which follow s when intensity of infection is significantly reduced.