The role of protozoa in the etiology of chronic urticaria

Chronic spontaneous urticaria and internal parasites--a systematic review

Chronic spontaneous urticaria (CSU) is defined as persistent wheals, angioedema, or both lasting for >6 weeks due to known or unknown causes. Some epidemiological studies and case reports suggest that internal parasite infections (PI) can cause CSU. Here, we provide a systematic overview of published findings on the prevalence and relevance of PI in CSU and we discuss possible pathomechanisms. The prevalence of PI in CSU was investigated by 39 independent studies and comorbidity reportedly ranged from 0 to 75.4% (two-thirds of these studies reported infection rates of 10% or less). The prevalence of PI in adult and pediatric CSU patients ranged from 0% to 75.4% and from 0% to 37.8%, respectively. CSU patients were more often diagnosed with protozoa and had a significantly higher risk of toxocariasis seropositivity and Anisakis simplex sensitization when compared to healthy controls. Patients with chronic urticaria more frequently had seropositivity of fasciolosis, Anisakis simplex sensitization, and the presence of Blastocystis hominis allele 34 (ST3) as compared with control subjects. In 21 studies, efficacy of treatment with antiparasitic drugs ranged from 0 to 100% (35.7% of 269 CSU patients benefitted). In 9 (42.8%) of 21 studies, more than 50% of efficacy was observed. The reported rate of urticaria comorbidity in PI patients in 18 independent studies is 1-66.7%. Urticaria including CSU might be a quite common symptom of strongyloidiasis and blastocystosis. Pathogenic mechanisms in CSU due to PI may include specific IgE, Th2 cytokine skewing, eosinophils, activation of the complement, and the coagulation systems.

Do not forget the stool examination!-cutaneous and gastrointestinal manifestations of Blastocystis sp. infection

Blastocystis sp. is one of the most common parasites in the human intestinal tract. This infection commonly is accompanied by diarrhoea and abdominal pain, but extraintestinal symptoms, such as skin lesions, may also accompany the disease. In this study, our aim was to assess the frequency, clinical symptoms and skin manifestations of confirmed positive Blastocystis sp. infections. Data of 80 patients with confirmed positive Blastocystis sp. infections were assessed retrospectively. The average age of the patients was 46.3 years of age (with a range between 13 and 85 years of age). The number of female patients was higher than the number of males (48 vs. 32; 60 vs. 40%). Gastrointestinal and dermatological symptoms and the results of routine biochemical and haematological blood tests of enrolled patients were collected and analyzed. The skin manifestations were analyzed using the data available (including descriptions, photos and histologies). We discovered that 11.25% of our enrolled patients exhibited skin manifestations associated to Blastocystis sp., mainly on the females. The occurrence of Blastocystis sp. was 6% in symptomatic patients who required medical attendance in the time period between 2005 and 2013. Of the 80 patients, 73.75% indicated that they had gastrointestinal symptoms: 40 patients complained of abdominal pain and 17 with blood in their stool, while other symptoms, such as meteorism (15 subjects), weigh loss (8 subjects), perianal pain or itching (6 subjects), passing stool with mucus (5 subjects), vomiting (2 subjects) and fever (2 subjects) were less frequent. The prevalence of abdominal pain in the cohort without skin lesions was higher compared to those patients with skin problems (p = 0.007). The mean value of C-reactive protein showed elevated levels, but eosinophils were within a normal range. In addition, we did not find significant difference in eosinophilia between patients with vs. without skin manifestations. Thus, we suggest that eosinophilia is not an obligatory laboratory finding in protozoon infections, such as Blastocystis sp. In the light of our results, we suggest a stool parasite examination for patients with skin lesions of unknown origin.