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Having visited Venezuala, why can't I donate blood - 2000

Question: I recently went to try and give blood at the Blood Transfusion Centre. I went through the questions successfully until the travel questions came up and when I revealed that I had travelled to Venezuela back in '95 and in a rural area I was promptly told "Sorry but you can't donate, due to the possibility of you having trypanosomiasis and their is no test for it at present. Try Dracula for your donation". So what is this strange disease, is there a test, and why aren't travellers made aware of this before they go?

Answer: Thanks for this interesting question. This is not such a strange disease really but it commonly is known by another name. Chagas' disease. It is caused by a single celled organism called a trypanasome, which infects the blood and more importantly other cells in our body that are responsible for our immunity.

Chagas' disease is only found in the Americas from Central America southwards with it's range ending before Patagonia. It is commonest in Brazil. The reason it has this distribution is that, like a lot of tropical illnesses, it needs an insect vector to spread the disease from human to human.

In the case of Chagas' it is the Cone-nosed bug. This is a large beetle like creature measuring up to 4 cms long, with a nose shaped like its name suggests. The way the traveller gets infected is by being bitten by the bug, which excretes the trypanasome that lives in its digestive tract and then the organism enters through the bite wound. Now the good thing about this illness is that the cone-nosed bug only likes living in the walls of mud huts in semi rural areas. These are rarely stayed in by travellers as they tend to be the houses for poorer locals on the fringes of the bigger cities.

Protection against the bug bites is simple by using a standard mosquito net and sleeping away from the walls of the hut, however there is no vaccination against this disease at the moment. Now the reason that you were told that by the Transfusion Service is that it can be very difficult to detect the infection after 3 weeks have elapsed after the bug bite, and it is very easy to pass on to others with a blood transfusion.

What I suggest is that anyone coming back from these sort of areas and who have stayed in adobe walled huts should have a blood test within 3 weeks of their return when Chagas' is detectable. But if you have been to these sorts of areas and not been tested on your return then as it is hard to detect the trypanasome in your body you cannot be considered for blood donation until a reliable test becomes available.

Symptoms of Chagas' vary from the bite itself with some local swelling around it, through fever and enlarged glands in the area of the bite, to some very serious complications of infection that can develop at a later date. Because the trypanasomes infect the immune cells they are very difficult to get rid of without destroying many other cells in the body, so there is no real effective treatment at the moment.

But don't be put off going to South America because if you stay in normal brick walled accommodation, camp in the jungle or use a mossy net you will be fine.


Dr Jules Eden

Dr Jules Eden
MBBs BSc MRCGP




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Information published on this website is not a substitute for professional medical care or advice but should be used only as an aid in understanding current medical knowledge. A Doctor should always be consulted for any health problem or medical condition.

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