Sweat is painting jazzy patterns on your dust-covered skin, your eyes are burning with salt, your fingers feel stickier than dried coke. The lake is dabbling invitingly, sun is glittering on the water. Water that promises the desiderated refreshment and cleanliness. It's quite natural to succumb to this temptation, to escape from heat and dirt in the chilling waveletts.

Putting aside the hippos, crocs, hookworms, giardia, medina worms and all other little sweeties, you are still running the risk of getting infected with bilharzia (schistosomiasis). This disease is caused by the larvae of parasitic distoma (worms), entering the skin, migrating through the body to the blood vessels of the lungs and liver. From there they advance to the veins traversing bowel or bladder. The worms will lay eggs which can either be passed in the urine or faeces. Whenever these contamined excretions are getting to fresh water, larvae will slip and host a specific species of snail. There they will ripen within 4-6 weeks and develop into so-called cercariae, which again will leave their temporary host. Now they will lurk for their final host: any mammal (including humans) coming into contact with the contamined water. Penetrating the mammals' skin the cycle starts anew.

Worldwide, approximately 250 to 300 million people are infected and help to spread the disease. Furthermore numerous irrigation projects and the building of new dams create ideal biotopes for the host snail. Therefore the number of infections is steadily increasing.

In case of an infection, different symptoms will appear: Only a few hours after the schistosomes have entered the body a cercariae dermatitis develops. It is characterized by a strong itching and a rash. Two weeks to two months later the infection reaches it's second stage. The Katayama Fever, which comes along with chills, cough and headache. Lymph nodes, liver and milt will enlarge. If there is a high concentration of larvae and eggs either in the bowel or in the bladder, abdominal pain accompanied by blood in the stools or urine will add. Within a few weeks these symptoms will regress. However, the infection will become chronical if there is no medical treatment.

Bilharzia can be life-threatening in all stages of infection. But we are favoured by fortune (compared to many people from Third World countries), because bilharzia medication is available and affordable for everyone of us. Therapy is quite easy, quickly done and doesn't have severe side-effects. This might be the reason for many travellers to jump into contamined waters overcareless and unconcerned.

Of course, it's up to you. But if you don't want to take the risk of an infection please resign from a swim in inland waters, specially in standing or slow-flowing waters with a dense under-water vegetation like seaweed or algae. Furthermore you should meet your needs of water for drinking and brushing your teeth from sealed bottles exclusively, not only to avoid bilharzia...

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