• When trying to analyze what triggered an allergic reaction keep
in mind that many reactions are “biphasic.” That is, after exposure to an
airborne allergen or a food, many people have not only an immediate
reaction, but also a second, delayed reaction (delayed up to 8 to 12
hours) after a single exposure.
• This is ragweed season. Keep in mind that rainfall releases more
ragweed pollen from the plants. Certain foods augment ragweed allergy,
especially melons and chamomile.
Now, say that fast three times with your mouth full of mushrooms. Shitake toxicoderma is a very common dermatitis in Asia, especially, China, Japan and Korea. However, it is being seen more commonly in the U.S. as the popularity of shitake mushrooms increases. The rash is fairly unique, consisting of a long linear array of urticaria. The skin looks like it has been whipped with cat-o-nine tails having red raised streaks that are very pruritic. The itchy lines can last for several weeks, and typically occur within a day of eating raw or cooked shitake mushrooms.
The mechanism of rash is felt to be due to Lentinam a polysaccharide found in the mushrooms that has immune-modulating effects. In fact, Lentinan has been used for chemotherapy in the treatment of colon and gastric cancers, It seems that individuals who get the rash have a hyper-immune response. Sun exposure can act as an adjunctive factor. The rash can be treated with steroids, usually topically, but if the problem is severe, oral steroids are used.
Since the article in the last issue of Allergic Reaction about Ramsay Hunt Syndrome from shingles, four patients from this office have commented on the much more common problem from shingles. That is eye involvement. Four individuals either had the complication themselves or knew a relative or friend with the eye involvement. All four of them felt that since the eye issue is so severe, people should know about it so they can protect themselves with the vaccine.
So here are some facts:
The most common complication of shingles (herpes zoster) is post-herpetic neuralgia. This occurs in about 20 percent of people who have shingles and can be a life-long source of recurrent pain in the area where the shingles broke out.
The second most common complication of shingles is herpes zoster opthalmicus (eye involvement), which occurs in about 2.5 to 3 percent of cases of shingles. Types of eye problems include conjunctivitis, iritis, uveitis and keratitis. All of these conditions can lead to varying degrees of loss of vision – including blindness. In some people the eye condition re-occurs repeatedly, even though the shingles don’t.
Once again, the best prevention for this complication is vaccination. Of note, when the vaccine was first released, the recommended age was 60 and older. Because the vaccine has proven to be so safe and so effective in preventing shingles and its complications, the age recommendation has been shifted to 50 and older.
The frequent rains this summer have led to a bumper crop of hungry mosquitoes. Although many repellants are available, the most effective compound seems to be DEET. It works because its scent is extremely irritating to biting insects, such as mosquitoes and fleas. Unfortunately, DEET is fairly allergenic with upwards of 30 percent of individuals developing a rash after repeated use. The types of rash seen are contact dermatitis (looks like poison ivy), eczema and urticaria (hives). The fact that DEET is a somewhat irritating chemical, and that it is repeatedly applied to the same skin areas, leads to the development of allergy.
Luckily, a new effective repellant has recently been developed – picordin. It, too, works because its scent dissuades biting insects; however, unlike DEET, it is not irritating or allergenic to the skin. Also, it is tolerated even in individuals already allergic to DEET.
Dear Dr. K: Please give us an update on the vaccine for peanut allergy.
Your request is very timely as I recently finished reading a pro/con editorial in the journal Asthma and Allergy Proceedings. I think these two editorial viewpoints sum things up quite nicely. The first of the two is titled, “Oral and Sublingual Peanut Immunotherapy Is Not Ready for General Use.” In this article written by the director of allergy at the University of Michigan, the focus in on the high frequency of patients who experience symptoms from the oral vaccine – including anaphylaxis – which required use of epinephrine.
Analyzing five recently published trials on peanut vaccine revealed that in each study, more than one half of patients had some type of reaction as the vaccine was built up. The reactions led to some parents removing their children from the study. In the five protocols reviewed the drop-out rate varied from 5 to 25 percent.
The author points out that the vaccine works by two mechanisms: tolerance and desensitization. Tolerance occurs by depleting the allergic antibody (IgE) to peanut. To maintain the depletion, the vaccine must be continued daily. If the vaccine is stopped, tolerance also stops because IgE rebuilds itself.
Desensitization is what occurs with traditional allergy shots. It leads to an increase in protective IgG against peanut (called blocking antibody), and a decrease in IgE. This type of protection is more desirable and can persist even after the vaccine is stopped. The author points out that even though the vaccines do seem to elicit both modes of protection, no long-term study has been done to show how long-lasting the benefit is. Therefore, the author concludes that for now, the vaccine should be restricted to research protocols until the risk/benefit ratio is better understood and the long-term benefit is fully determined. The contrasting editorial is from the Paul Foster School of Medicine in El Paso, Texas, and is titled, “Oral Immunotherapy for Peanut Allergy in a Clinical Practice is Ready.” This author argues that the annual rate for accidental peanut ingestion is 10 percent which leads to severe symptoms, including anaphylaxis and the need for epinephrine. This number far exceeds the number of vaccine-induced reactions requiring epinephrine. He further argues that peanut allergy has a major effect on the quality of life of the patient and his/her family, and can be psychosocially debilitating. Also, unlike other food allergies where remission is high, less than 20 percent of peanut allergic children have spontaneous remission. Finally, he cites the outcome of three clinical trials done in office-based settings that treated a total of 150 children. Of these, 111 were successfully able to take the vaccine and were protected in a purposeful challenge of eight peanuts.
Spleenectomy (surgical removal of the spleen), or functional asplenia, is a significant risk factor for meningitis. And curiously, the most common bacteria to cause meningitis in these patients is the germ pneumoccus (most commonly associated with bronchitis and pneumonia). Patients with splenic dysfunction lose an important site of both antibody production and immune cell production. They also can no longer filter blood-borne bacteria; hence, a germ that normally causes a respiratory infection can get into the bloodstream and land in the brain.
In the general public, pneumoccus accounts for 70 percent of the cases of meningitis, and is even a more common cause in people with dysfunctional spleens. The most common reason for surgical removal of the spleen is because it ruptured from blunt trauma, such as in sports injuries or motor vehicle accidents. The most common causes for functional asplenia are congenital hyposplenism, sickle cell disease, celiac disease, bone marrow transplant, HIV infection, liver cirrhosis and lymphoma. Luckily there is an excellent way to prevent this meningitis risk and that is to take the pneumovax, also known as PPV-23 (23-valent polysaccharide pneumococcal) vaccine.
One caveat though, is to be sure to measure post-vaccine antibodies. Because the spleen isn’t functional, there is a chance that a single vaccine may not be fully effective. By measuring the antibody levels after vaccination, a determination can be made if a booster is needed.