With the rainy season on in the Dhofar region, swimming in wadis or small ponds can lead to a parasitic disease called schistosomiasis, warns an expert. Dr Euan Scrimgeour, a former associate professor in infectious and tropical diseases at Sultan Qaboos University, told Muscat Daily that the disease is caused by an obligate parasite of humans and snails it requires both humans and snails to survive.
The onset of the disease begins when the schistosoma worm, a parasitic flatworm, penetrates human skin and then enters the bloodstream. Larval forms of the parasite released by freshwater snails penetrate the skin of humans. "The infection is contracted when humans come in contact with the parasite in contaminated water, as is the case in Salalah," he said.
On entering the blood stream, if the parasite reaches the liver, it continues to grow in it, and migrates to the gut or gall bladder after developing. It then lives in the veins, draining the intestine. "This disease, which infects only the blood vessels of the intestine, is common in the Dhofar region and is a matter of serious concern."
"The small water bodies near Salalah are full of these snails, which cannot be eradicated. The flukes develop in snails and grow into huge numbers of microscopic larval flukes, which swim and penetrate the skin of humans in the water," Dr Scrimgeour explained.
To prevent the disease, freshwater sources must be monitored to prevent snail buildup and people warned not to enter snail infested water bodies.
The disease is most likely to affect small children in Salalah. "Most of the signs forbidding excretion and swimming in freshwater springs have been removed by unauthorised people around Wadi Sahanout near Salalah. The area is known for Biomphalaria arabica snails, the vectors (an organism that transmits a disease or parasite from one animal or plant to another) for Schistosoma mansoni."
Listing the symptoms, he said, "Blood will be present in the stool six to eight weeks after bathing in infected freshwater. Later the liver gets swollen with eggs from flukes. Chronic infection can be fatal. Within days of getting infected, some people develop rashes or itchy skin. Fever, chills, cough and muscle aches begin within a month or two of infection. Some people have no symptoms in the early phases of infection."
There is a need for constant vigilance at foci (the principal site of an infection or disease) where vector snails exist in Salalah. With a few cases reported annually to the Ministry of Health, the diagnosis of schistosomiasis is critical to successful treatment. "It is likely that many cases are not diagnosed or simply go unreported," Dr Scrimgeour said.
© Muscat Daily 2011
