Certain worms which may be present in a child s intestine like roundworm,whipworm,hookworm(termed as helminths) are brown in colour .Their presence in child s intestine is really of concern because they may lead to severe malnourishment of your child,may cause intestinal obstruction or even some allergic reactions also.The white worms which you are aware of are actually the commonest type of worms infesting a child s intestine.They are the pin worms and are usually mild infection and do not cause serious complications. Once your child has expelled a brown worm in his stool,I think he should have a stool examination done to examine the exact type of worm from any cysts or ova, if possible. Anti helminthic medications should be taken by him in full course to get rid of these worms.He should also be checked for presence of any other problems which may be due to presence of these worms and treated accordingly.Certain precautions must be taken for future like 1.elimination of meat products,refined carbohydrates,processed foods which can provide a friendly environment for these worms to survive in the intestine 2.consume boiled water and well cooked food and take extra precautions for food and water during travel 3.Thorough cleaning of the anal area and proper washing away of stool particles 4.practise handwashing before and after each meal and on regular basis,maintain good hygeine by proper regular washing of bedsheets and mattresses 5.prevent him to play in the soil bare foot 6.take regular deworming sessions from your family physician. Its nothing to worry about much.But do not ignore the fact and get a medical check up done. Hope I have been able to answer your query.