“Skeeter Syndrome” and other mosquito hypersensitivity reactions at a sleepaway summer camp in flooded Rainy River Basin

Abstract

Introduction In the summer of 2022, the Rainy River Basin in Northern Minnesota and nearby Ontario Canada experienced historic flooding with the highest levels in over 70 years, and with water levels peaking on June 15th. This flooding caused unusually large amounts of standing water in the region and resulted in an atypical year for mosquitos in the region, particularly the Summer Floodwater mosquito, or Aedes vexans. Mosquito bite hypersensitivity is characterized by edema and skin reactions. There are some known causes of hypersensitivity reactions to mosquito bites. Epstein Barr Virus, natural killer (NK) cell lymphocytosis, and chronic urticaria are conditions known to be associated with mosquito hypersensitivity. Children with atopy, and grass allergies are more likely to have mosquito hypersensitivity. However, the exact cause of these associations is unknown. Methods We observed mosquito bite reactions in a camp of 108 campers and 52 staff located in the Rainy River Basin, and with wilderness trips throughout Northern Minnesota and Southern Ontario, Canada. We tracked reactions throughout 3.5-week sessions for campers and over 9 weeks for staff. Results Unusual hypersensitivity reactions were observed in the Rainy River Basin near Rainy Lake at a sleep away summer camp among staff and campers. These reactions were indicative of allergic reactions or “skeeter syndrome.” Skeeter syndrome is a rare allergic and often severe allergic reaction to mosquito bites resulting in blistering and swelling at the site of the bite, and in less severe cases bruising. Reactions that were observed at the camp included periorbital edema, ulcerative lesions, blistering, and ecchymosis. One case in particular resulted in swelling at the joint of multiple mosquito bites, resulting in movement restriction and pain. Some reactions were observed on international staff who had no previous exposure to mosquito bites while others were observed on individuals with previous mosquito exposure. Some reactions that cause breaks in skin continuity are of concern due to increased risk of complications such as cellulitis and, in rare cases, systemic infection and sepsis. Conclusions As natural disasters become increasingly common with climate change, preventative measures should be taken in areas experiencing lake and river flooding to avoid mosquito hypersensitivity reactions. Best practices include using permethrin on clothing and applying products with 20-50% DEET concentrations every 6 hours to exposed skin. Children and pregnant women can use Picaridin and IR3535 as safe alternatives to DEET. In cases where hypersensitive reactions did occur, treatment was initiated with diphenhydramine cream and bandages to prevent skin breakdown or infection from itching. We also used 0.1% hydrocortisone cream and wrapped extremities to prevent swelling.