The health service has detected 72 cases of the illness cryptosporidiosis in Gwynedd and Anglesey since the start of October.
The infection can be spread through drinking water
The National Public Health Service have issued advice on the parasite which causes the stomach bug.
Q: What is cryptosporidiosis?
Cryptosporidiosis is a diarrhoeal disease of humans and animals, caused by a microscopic parasite called Cryptosporidium. The organism is common in farm and domestic animals, and is passed on through their manure. It is present in the environment at low levels all the time, but higher levels are common in springtime, particularly when heavy rain washes the parasite into the ground and into rivers and lakes.
Q: How is cryptosporidiosis spread?
It can spread to humans by a variety of routes. Person-to-person spread is an important source of infection if care is not taken with personal hygiene. Contact with farm animals - and sick pets - can put people at risk of infection. Water supplies may be vulnerable to contamination with Cryptosporidium, and the infection can be spread via drinking water.
Q: What precautions can be taken against cryptosporidiosis?
Personal hygiene is very important, particularly if there is someone with diarrhoea in the household or if farm animals or sick pets have been handled. Hand washing is important after using the toilet, or a soon as possible after touching potential sources of infection - farmyard animals, sick pets, manure on the ground or people with diarrhoea. Good hygiene is particularly important before handling food.
Q: What is the current problem in Gwynedd and Anglesey?
There has been a recent increase in cases of a stomach illness caused by the cryptosporidium parasite. The increase coincides with a higher rate of infection in people in Gwynedd and Anglesey, especially those who are supplied with water from the Cwellyn Reservoir. As a precaution, people in the Gwynedd and Anglesey areas are being asked to boil bottled and tap water before using it.
Q: What are the public health authorities doing about this?
The National Public Health Service, environment health officers, local health boards and the water suppliers are working together to ensure that any possible risks to the public are kept to a minimum. By asking people to boil their tap water before use, we are preventing people from being affected by cryptosporidiosis. Welsh Water is checking the treatment works and carrying out environmental investigations to ensure that any cryptosporidium in the water is removed.
Hygiene advice has been issued to swimming pools. People who have had cryptosporidiosis are advised not to go swimming for two weeks after they have recovered.
Q: What should I do if I become ill?
The infection will usually clear up by itself in a healthy person, although this may take several days. You should consult your GP if diarrhoea is unduly prolonged or if you are at all concerned. A GP should also be consulted if the person affected is very young, elderly or frail. It is generally recommended to increase your fluid intake if you have diarrhoea.
Q: What treatment is available for cryptosporidiosis?
There is no effective treatment for cryptosporidiosis, which is why people with immune problems are particularly advised to avoid contracting the infection in the first place if at all possible.
The helpline number for people with questions or concerns is 0845 850 9850. It is open seven days a week from 0900 - 1700 GMT.