­   Should this situation sound familiar to you: stop handling bloodworms immediately and start feeding your aquatic pets other foods. Your body shows a hypersensitivity to bloodworms, meaning your immune system is being triggered excessively. Or in other words: you are allergic to bloodworms. In severe cases you will need to look for medical help right away, and tell the medical personnel you handled midge larvae. Hypersensitivity to bloodworms has been frequently reported in literature, e.g. by Ballesteros et al. (2006)[1] or Meseguer et al. (2013)[2], to cause urticaria (also called the hives, a sort of skin rash), rhinoconjunctivitis (a runny nose, sneezing, nasal congestion), asthma, angioedema (most common is the swelling of the lips and eyes) and even anaphylaxis. You should not only stop handling bloodworms but even avoid coming close to bloodworms.

ALLERGY WITH REFERENCE TO INSECTS

   Bloodworms are actually not worms but the aquatic larvae of non-biting midges as explained here. Fully grown midges are insects which look like large mosquito’s (they can reach a length of around 1 cm) and which is why bloodworms are also called ‘red mosquito larvae’ in most European countries. The red color of the worms is caused by the presence of a certain type of hemoglobin molecules called erythrocruorins, these are very large molecules occurring in the hemolymph of certain invertebrates and their function basically is the same as that of hemoglobin in vertebrates: the transport of oxygen. Midge larvae can actually survive and thrive in anoxic (oxygen poor), stagnant to slow-moving bodies of water due to the presence of these erythrocruorins, which have a very strong binding affinity for oxygen enabling the larvae to take up the very limited amount of oxygen available in an anoxic environment whilst most other animals can not.

   Unfortunately for us, humans, erythrocruorins have been proven to be able to act as a powerful allergen to some people. An allergen is a substance (usually a protein, glycoprotein, peptide or a lipoprotein) which provokes a serious response from our immune system. Not everybody is affected by erythrocruorins, there seems to exist a certain genetic predisposition in people towards being allergic to certain kind of insects. Not only bloodworms are known to be a potential cause for insect allergies, but so are house mites, certain beetles, mealworms, silkworms, cockroaches etc.[3]

   Adult midges do not contain any hemoglobin anymore but unfortunately some species were found to contain tropomyosin[4], another protein known to be able to act as a powerful allergen (e.g. in American cockroaches, spiny lobsters and dust mites). Adult midges are not commercially sold but form a serious problem in certain parts of the world (e.g. Egypt, Sudan, Singapore, Japan, Korea, certain parts of the USA, …) for those people being allergic to tropomyosin when a mass emergence of midges takes place.

FREEZE-DRIED BLOODWORMS: A NO-GO ZONE!

   If youcan not handle frozen bloodworms, you should definitely avoid coming in the vicinity of freeze-dried bloodworms. As most moisture has been removed from freeze-dried bloodworms, these worms are very brittle and they can easily turn into a fine powder. These powdered, very lightweight bloodworm particles can easily become airborne and inhalation of these particles will cause a larger allergic reaction as compared to touching frozen bloodworms. Some people don’t even need to inhale the freeze-dried bloodworm particles but already start reacting when their skin comes into contact with these particles.