Diarrhoea is one of the leading killers of children under the age of five in developing countries. Diarrhoea is rampant in India, with diarrhoeal diseases being the most prevalent of all waterborne diseases in the country. Diarrhoea leads to the third highest proportion of child deaths in South Asia.
A study titled ‘Cryptosporidium concentrations in rivers worldwide’ published in the journal Water Research informs that one of the important causes of diarrhoea is cryptosporidiosis, a parasitic infection which is a leading cause of diarrhoeal disease among children under the age of two in developing countries.
For example, cryptosporidium related deaths in children under two are estimated to be as high as 202,000 in both Sub-Saharan Africa and South Asia. Community based studies in India show that cryptosporidium alone contributes to 3.9 to 7.1 million diarrheal episodes and 58,000 to 146,000 deaths each year in children under two years of age.
Cryptosporidiosis is a diarrhoeal disease caused by a parasite named cryptosporidium. The parasite completes its lifecycle in humans and animals. The disease spreads from person to person after the parasites are shed into the environment; and their oocysts are found in soil, food, water, or on surfaces that have been contaminated with faeces from infected humans or animals. Oocysts are essentially thick walled and sturdy cysts or spores released by the parasite that are highly infectious and can infect a person through water and food.
Infection often occurs through water, such as drinking or bathing in river water contaminated with faeces. Cryptosporidium oocysts can tolerate various environmental conditions and can survive in water and soil for many months. They can be transported long distances in the air and also flushed quickly into water sources because of their small size. The common symptoms of cryptosporidiosis include watery diarrhoea, stomach cramps and pain, dehydration, nausea, vomiting and fever.
The study attempts to estimate the concentration of cryptosporidium parasite oocysts in rivers by using a global model that assesses and computes pathogen concentrations in rivers. The study takes into consideration human and animal sources of infection, the impact of factors such as the role of surface runoff in transport of oocysts from land to rivers, the impact of temperature and seasons on oocyst survival and spread, and the impact of soil, river sedimentation and river characteristics on the spread of infection.
The paper calls for the need to conduct more studies to gain insights into the transmission of cryptosporidium oocyst through rivers that can help in: