Health Watch: The Bilharzia Parasite

2 April 2009

Killer Fact: About half of all swimmers in Lake Malawi test positive for Bilharzia when checked at InterHealth or other tropical centres...

So, what is Bilharzia?

Bilharzia is caused by a parasitic worm (schistomes) with a smart life cycle. In fresh water certain types of snail are present that are carriers of the worm. If you’re unlucky, these worms will penetrate your skin, do a grand tour of the body, and then settle down in the blood vessels surrounding your bladder or large intestine. Here they enjoy themselves producing eggs which when released cause irritation of the bladder or bowel before rediscovering the outside world.
Where is it found?

Bilharzia can only be contracted in FRESH WATER. Most travellers pick up the parasite in sub-Saharan Africa in Lakes Malawi, Victoria, Kariba and Volta. However, instances have been known in North Eastern Brazil, some islands in the Caribbean and parts of the Middle East, the Philippines, Indonesia and Southern China.

Killer Fact: About half of all swimmers in Lake Malawi test positive for Bilharzia when checked at InterHealth or other tropical centres.

The symptoms

If you are very unlucky you’ll get acute Schistosomiasis or Katayama fever. This can mimic malaria and typical symptoms are fever, muscle ache, cough, diarrhoea and itchy skin. This usually happens within 1 or 2 months of infection.
About half of all travellers who become infected show no symptoms, and for those who do, tiredness is the most common. Occasionally, after months or years, more serious symptoms can occur such as blood in the urine, which is why it’s worth getting checked and treated. Most people with Bilharzia have this discovered by a blood test after returning home. Any form of Bilharzia can cause fatigue, so before anyone labels you with Chronic Fatigue Syndrome make sure you have a Bilharzia blood test.

What can I do about it?

Avoid any contact with infected water in areas where Bilharzia occurs. That means giving that alluring lake in sub-Saharan Africa a miss.

Don’t swim, wash, paddle, push vehicles or wade through rivers or water, especially if slow–flowing or stagnant.
Don’t drink water, which could be infected without boiling it for at least one minute first.
Wear protective foot-wear if you are walking through mud or damp areas near rivers or lakes.

If you have foolishly exposed yourself, recent research from the London School of Hygiene & TropicalMedicine has found that you can still reduce your risk. Apply 50% DEET based insect repellent over your whole body excluding scalp and the genitalia, 8 to 12 hours AFTER exposure. This penetrates the skin and helps to kill larvae, which remain under the skin for some hours before moving on. A brisk rub down with a towel after a swim is also thought to reduce the risk.

But the advice still remains – avoid swimming in the lake!

How is it treated?

Once Bilharzia has been diagnosed it can be treated by taking Praziquantel (PZQ), a relatively low-toxin drug. For people of average weight, 4 or 5 of the 500mg or 600mg tablets is needed. However, Praziquantel is hard to get hold of in some countries, including the UK, but specialist travel centres will have it and we keep it at InterHealth. If you think you may be displaying Bilharzia symptoms, give our friendly reception team a ring on 0207 902 9000 to arrange a consultation.

In summary

Try to avoid fresh water when on your travels. If you have been at any risk of catching Bilharzia then arrange a blood test when you get home, ideally at least 60 days after your last exposure.

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InterHealth provides holistic healthcare to people committed to making the world a better, fairer andhealthier place, including missionaries, relief and development workers, GAP volunteers, expeditioners, UK charity workers and those in Christian Ministry.

As a centre for international travel medicine our team of 15 health professionals look after individual travellers and staff from over 300 organizations. Our medical, psychological health, occupational health and travel health services support people in the UK and internationally. As medical advisor to many of the major international agencies involved in humanitarian relief and poverty reduction across the world, we support many dedicated staff and volunteers to be physically and psychologically fit, resilient, and prepared for tough environments and demanding work.

Written by Dr. Ted Lankester Author of The Berlitz Travel Health Guide and Director of Healthcare at travel health charity InterHealth.

Press enquiries: +44 (0)207 902 9038

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