Biology
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What is the diagnosis in this case?
The diagnosis in this case is swimmer’s itch, also known as Cercarial Dermatitis. This infection occurs when the skin is infested by larvae (cercariae) of non-human schistosomes, which are normally hosted by small mammals and birds (Horák et al., 2015). A person acquires swimmer’s itch when his or her skin is exposed to fresh water. The larvae enter the integral human skin within a small period of time, i.e. within minutes. This type of infection occurs in people who are constantly exposed to water bodies i.e. swimmers. In this case, the patient has been a member of the swimming team for a while; therefore, the development of swimmer’s itch infection can be attributed to the patient’s constant exposure to water.
Why was the potassium hydroxide preparation from his hands negative?
The potassium hydroxide preparation (KOH test) from his hands is negative because the infection is non-fungal. This type of test is usually carried out to test the presence of fungi (e.g. yeast or dermophytes). It is important to note that lesions of swimmer’s itch or eczema may look like the peeling patches of a superficial infection caused by fungi. Therefore, the KOH test was done to rule out a fungus infection on the patient’s hands.
What are some of the organisms involved in this type of infection? Name at least 3.
The cause of the Cercarial Dermatitis is the larval stage of a group of flatworm parasites. These parasites are from the family of Schistosomatidae. Gigantobilharzia and Trichobilharzia are the most common genera associated with Cercarial Dermatitis in human beings. Another cause of swimmer’s itch infection can be attributed to schistosome parasites of non-avian vertebrates (Horák et al., 2015). A good example of the parasites is the Schistosomatium douthitti, which infects rodents and snails. Schistosoma bovis and Bilharziella polonica have also been known to cause swimmer’s itch.
What are some of the other major clinical subtypes of infections caused by these organisms?
One of the major clinical subtypes of infection caused by these organisms is bilharzias. This is a parasitic infection caused by worms. An individual can get infected with bilharzias when their skin is exposed to contaminated fresh water. The parasites penetrate the skin and then migrate to the lungs and liver’s blood vessels. They may then migrate to the veins located around the bladder or bowel. Eggs will be laid by the worms and will be passed in faeces or urine, or remain in the host’s tissues (Colley et al., 2014). Fresh water can be infected if people with the infection defecate or urinate in it.
Another major clinical subtype of infection that can be caused by the organisms is urinary schistosomiasis. This type of infection occurs when the parasitic worms are lodged in the urinary tract, and it can cause blood in the urine. If the infection is not treated, it can ultimately cause malnutrition, anaemia, and kidney failure. Health professionals usually diagnose the infection by checking if the urine has the worm eggs. Intestinal schistosomiasis is yet another clinical subtype infection, and it develops when the egg worms are lodged in the wall of the intestine, and lead to a reaction refers to granulomatous reaction (Colley et al., 2014). The infected person may then develop an abdominal swelling that looks like a potbelly.
What treatment would be recommended for this patient?
It is not necessary to treat swimmer’s itch when the itching spots are few. Once a person gets the reaction, he or she should lightly rinse the skin with isopropyl (rubbing) alcohol. The next step is to coat the skin with calamine lotion. Notably, the doctor can prescribe a mild corticosteroid cream (1 percent hydrocortisone) or an antihistaminic to control the infection. The patient should be advised avoid scratching the rashes constantly since doing this can cause abrasions and more severe skin infections (Horák et al., 2015). Other treatment options for Cercarial Dermatitis include application of baking soda paste to the rash, cool compresses and bathing with baking soda.
References
Colley, D. G., Bustinduy, A. L., Secor, W. E., & King, C. H. (2014). Human schistosomiasis.
The Lancet, 383(9936), 2253-2264.
Horák, P., Mikeš, L., Lichtenbergová, L., Skála, V., Soldánová, M., & Brant, S. V. (2015).
Avian schistosomes and outbreaks of cercarial dermatitis. Clinical microbiology reviews, 28(1), 165-190.
