Swimmer's Itch: Frequently Asked Questions
What causes swimmers itch?
Swimmer's itch is caused by a blood fluke common in waterfowl. The itching is caused when the fluke, while in the immature stage of its life cycle, mistakes you for its primary host -- waterfowl -- and burrows into your skin. Aside from the annoying itching, swimmer’s itch is harmless to humans. The irritation can last from two days to several weeks, depending on the individual’s susceptibility. Preventive measures can be taken, and there are no permanent effects from swimmer’s itch.
Source: dnr.wi.gov
Swimmers itch is caused by parasites related to the life cycle of snails in the lakes and has nothing to do with the applied herbicides.
Source: lindenhurstil.org
What is swimmer's itch?
Swimmer's itch or schistosome cercarial dermatitis is a skin reaction that certain people have to the entry of a larval stage of certain flatworms into the epidermal layer of the skin. After the parasite enters, it dies and may cause dermatitis in individuals who have been previously sensitized. This sensitivity will rarely disappear; it usually get worse to subsequent exposures.
Source: www.hope.edu
Cercarial dermatitis, most commonly known as swimmer's itch, is a skin rash caused by an allergic reaction to infection with certain parasites. For further information on swimmer's itch, please visit: www.cdc.gov/ncidod/dpd/parasites/schistosomiasis/factsht_cardmer
Source: www.nassaucountyny.gov
What are the symptoms of swimmer's itch?
Sensitized people get swimmer's itch when the cercarial stage (originating in specific snail species) accidentally enters their skin. Usually within 30 minutes, a small red spot appears at the site where the cercaria penetrated. This red spot will continue to increase in size for the next 24-30 hours. The raised, reddened spot is now called a papule. It will continue to itch for up to a week. Papules are limited to areas of the body that get exposed to water because cercariae can not live out of the water. ...
Source: www.hope.edu
How is swimmers itch treated?
If you think you may have contracted swimmers itch (or any other aquatic dermatitis), it is recommended that you seek a physician's advice for treatment. Treatment is symptomatic and generally includes the use of topical anti-itch and antihistamine medications. Antimicrobial drugs may be used to treat secondary infections brought on by repeated scratching. The rash and itching usually disappear within a week of infection, depending on the degree of exposure and the individual’s sensitivity.
Source: www.co.suffolk.ny.us
What are symptoms of swimmers itch?
Symptoms include an initial itchy or tingling sensation that usually subsides quickly, leaving the infected individual with tiny red spots at the sites of penetration. After a number of hours, intense itching may develop and the red spots enlarge to form pimple-like bumps (papules). As with most allergens, repeated exposure to the cercaria usually results in increased sensitivity.
Source: www.co.suffolk.ny.us
What is swimmers itch?
Swimmers itch is a dermatitis that develops on exposed areas of the skin after contact with waters containing cercaria (larval forms) of avian schistosomes (parasitic flatworms). The rash that develops is an immune response caused by penetration of the skin by the cercaria. Waterfowl are the usual hosts of these schistosomes, with humans accidentally infected. Typically, adult worms live in the blood of their avian hosts (waterfowl) and produce eggs that are passed in the feces. ...
Source: www.co.suffolk.ny.us
What is swimmers itch and how can it be avoided?
Swimmers itch are small red bumps that itch and appear after swimming on hot summer days. It is caused by a small parasite that is harmless to humans. To avoid swimmers itch, towel dry upon exiting the lake and shower if possible. See the swimming beaches section for more information.
Source: www.minneapolisparks.org
What is the cause of Swimmers Itch?
Several species of parasites known as blood flukes (all in the genus Schistosoma) are known to cause swimmers’ itch. The adult parasites live in the bloodstream of a host animal, which may be a bird, fish, turtle or muskrat. The adults produce eggs which are released from the host and are subsequently ingested by snails. A free-swimming larva later emerges from the intermediate-host snail looking for a suitable host animal. ...
Source: www.wasecalakes.org
Can swimmer's itch be eliminated completely?
Under normal circumstances, it can be greatly reduced, possibly eliminated. The success and cost of a control program follows the law of diminishing returns as illustrated below:
Source: www.hope.edu
Is there other information available on swimmer's itch?
Yes, more than a thousand articles have been published on the topic; in addition, we have several papers that were published in recent years. Ours can be obtained from libraries or for a nominal fee from us.
Source: www.hope.edu
Will swimmer's itch spread?
No, a papule forms only where a cercaria has entered the skin of a person. If the person gets exposed to more cercariae, additional papules will form.
Source: www.hope.edu
What is the relationship of snails to swimmer's itch?
Certain stages of the parasites that cause swimmers' itch must cycle through snails. Larval stages develop and reproduce in the internal organs of the snail. Each day, a couple thousand of these free-swimming cercariae emerge from the snail but do not feed and therefore will not live for much more than 24 hours in the water.
Source: www.hope.edu
How common is swimmer's itch in Michigan?
It is widely scattered throughout Michigan, but uncommon in the thumb region. Major outbreaks occur on the larger recreational lakes in the northern part of the Lower Peninsula. Nearly every lake in Michigan has the potential to support the snails and birds that host the schistosomes that cause swimmer's itch.
Source: www.hope.edu
Is swimmer's itch found only in Michigan?
No, cases have been reported from nearly every state as well as from all of the provinces of Canada. In North America, most of the problems of swimmer's itch occur in the northern tier of states, north to Alaska. In addition, swimmer's itch has been reported from more than 30 countries.
Source: www.hope.edu
What is Swimmer’s Itch?
Itchy red spots that can occur on your skin after swimming in the lake and may last several days. They are caused by a parasite that lives in tiny snails and aquatic birds during two stages of their life cycle. It can be prevented by showering or towelling off thoroughly after swimming, and by staying away from the shallow areas where geese, ducks, and other waterfowl congregate. It can be treated with 1% hydrocortisone cream. Swimmer’s Itch rarely occurs and should not be a deterrent to most swimmers. More details ......
Source: www.olwqs.org
What types of control are used in Michigan to combat swimmer's itch?
For more than 50 years, the application of copper sulfate as a molluscicide was used on some of the larger recreational lakes to break the life cycle by killing the snail intermediate hosts. Although this method is still used, fewer lakes are requesting permits because of the uncertainty of long-term consequences to a particular lake and because the results are unpredictable. A second method that has recently been introduced is to remove the adult worms from the birds hosts with an antihelmintic drug. ...
Source: www.hope.edu
When does the first outbreak of swimmer's itch occur?
Often during the first warm period in the spring, usually in late May or early June. In 1998, swimmer's itch cases were reported during the second week of May. These outbreaks are delayed in the more northern regions of Michigan.
Source: www.hope.edu
Are birds important to the organisms that cause swimmer's itch?
Yes, many species of birds and some rodent species can harbor the adults parasites within their blood vessels. Some common hosts include common mergansers, mallards, Canada geese, swans, red-winged blackbirds, etc., as well as muskrats and mice.
Source: www.hope.edu
What can be done to prevent or to reduce swimmer's itch?
avoid swimming for long periods in shallow water
avoid swimming in areas where swimmer's itch is a problem and where there is an onshore wind
towel off immediately after leaving the water may help reducing swimmer's itch caused by cercariae of some species that enter only as the water dries on the skin
post appropriate signs on beaches where swimmer's itch is an annual problem
do not encourage birds to stay in your area by feeding them
avoid placing rip-rap on your shore. ...
Source: www.hope.edu
Why may swimmer's itch be a problem one year but not the next?
The following are factors that may determine whether swimmer's itch may be a problem on a specific lake at a given time:
distribution and number of snails that can serve as intermediate hosts
distribution and number of bird hosts that can serve as hosts for the adult worm
wind direction
water currents
number of hours that people stay in the water
time of day
sensitivity of the individual to swimmer's itch. All of these factors can change on an annual basis.
Source: www.hope.edu
Is there reason for optimism for swimmer's itch control in the future?
We think so. During the last 15 years, many advances have been made with the help and commitment from various lake associations in the Leelanau Peninsula. Currently, we are conducting experiments to develop better methods of control.
Source: www.swimmersitch.org
Why do children often develop the most severe cases of swimmer's itch?
They usually swim more regularly, their skin may be more sensitive, and young children have a tendency to stay near the water's edge. It appears that cercariae may concentrate near the shoreline.
Source: www.hope.edu
Are Canada geese and mute swans important hosts for swimmer's itch?
No, they usually are not because the snail intermediate hosts for the schistosomes that cycle through them are snails found typically in marshy areas where people do not swim. Remember, the stage that causes swimmer's itch comes from the snail and not directly from the bird host.
Source: www.hope.edu
How many species of avian schistosomes can cause swimmer's itch in Michigan?
Nobody knows the answer to this question. Based on previous work, it appears that there may be from 12-15 species in Michigan. This question is difficult to answer for several reasons. First. there are a large number of birds that potentially can serve as hosts for the adult worm. Second, the adult worms are so small and so difficult to remove from the blood vessels that few people have attempted to work out the classification scheme. A final difficulty is that for most species, the life cycles are not known. ...
Source: www.hope.edu
What can individuals do who have a bad case of swimmer's itch?
They should see a doctor and ask for a prescription to relieve the itching and for a topical cream that will reduce the swelling. Ken-tox is a nonprescription cream that gives relief.
Source: www.hope.edu
What can our lake association do about swimmer's itch?
It can do several things including the following: educate members about swimmer's itch, assess the problem of swimmer's itch on its lake, make recommendations for relieving the itching, and begin a control program if swimmer's itch is a regular problem.
Source: www.hope.edu
Do all snails carry the organisms that cause swimmer's itch?
No, there are at least nine species reported in Michigan that can serve as intermediate hosts for the parasites. Remember that most species of schistosomes have only one snail species that can serve as its host.
Source: www.hope.edu
How many hosts are there in the life cycle of the parasites that cause swimmer's itch?
There are always two, a snail intermediate and vertebrate final host. The parasite must be transmitted from snail to bird and from bird to snail. It can never go from snail to snail or from bird to bird.
Source: www.hope.edu
