Musi pollution: Hookworm threat due to use of sewage in agriculture

December 22, 2008
By Syed Akbar
Hyderabad, Dec 21: Hyderabadis, who consume fruits and vegetables grown over 3,600 hectares under Musi ayacut, run the risk of severe worm infection that may cause appetite loss, abdominal pain, shortness of breath and a variety of skin diseases.
According to a joint study by the London School of Hygiene and Tropical Medicine and the International Water Management Institute, Hyderabad, farmers as well as consumers are hit by use of sewage or wastewater in agriculture in and around Hyderabad. As unpolluted water is not available in sufficient quantities in the State capital region for agriculture, scores of farmers in the downstream of Musi are increasingly going in for untreated water for their crops and orchards,
exposing their health as well as of consumers.
If the WHO standards are to be followed, wastewater used in Hyderabad to irrigate is unfit for crop production.
"Intestinal nematode infections have been identified as the main health risk associated with this practice. To protect consumer and farmer health, the World Health Organisation has established an intestinal nematode water quality standard... The use of wastewater poses a number of health risks. Predominant among these is the risk of intestinal helminth infection," Jeroen H J Ensink of London School of
Hygiene and Tropical Medicine, told this correspondent.
The study found that in Hyderabad around 250 households use wastewater from the Musi river to irrigate 500 hectares of land. Downstream of Hyderabad, farmers, with the help of weirs, irrigate 3,100 hectares of agricultural land.
For the purpose of the study, the research team divided the city and its suburbs into three zones, centre of Hyderabad (high concentration of hookworm eggs), peri-urban zone of Hyderabad (medium concentration of hookworm infection) and villages downstream of the river Musi.
The team found prevalence of hookworm and heavy hookworm infection and other intestinal parasites like Ascaris (giant round worms) and Trichuris (whip worms). Overall, 31.2 per cent of persons, who formed part of the study, were infected by at least one intestinal nematode infection. Of these, hookworm is the most prevalent (29.8 per cent), followed by Ascaris lumbricoides and Trichuris trichiura.
The mean intensity of infection ranged from 35 eggs per gram of faeces (epg) for hookworm to 1.7 epg for T. trichiura. The highest intensity of infection in a person was found for hookworm (1,789 epg), followed by A. lumbricoides (1,333 epg) and T. trichiura (336 epg).He said a significant difference in the prevalence of hookworm, Ascaris and Trichuris was found among the three city zones. Farming families
in centre of Hyderabad had a significantly higher prevalence of hookworm, Ascaris and Trichuris infection. In addition, they also exhibited a significantly higher intensity of infection for all three infections relative to farming families in other two zones.
"Among all persons, use of untreated wastewater, when controlled for confounding variables, was associated with an almost four-fold increased risk of hookworm and heavy hookworm infection. This result was in contrast to the use of partially treated wastewater, which showed no significant association with hookworm infection when controlled for confounding variables. Use of untreated wastewater further showed a greater than five-fold increased risk of Ascaris and Trichuris infection.
Use of partially treated wastewater was associated with a greater than three-fold increased risk of Ascaris infection," Jeroen Ensink said.
The highest risks were associated with use of untreated wastewater, and use of partially treated wastewater was associated only with an increased risk of Ascaris. Use of untreated wastewater was also associated with a higher intensity of infection, especially for hookworm infection.