Cimex (Acanthia) lectularia[1068] (Cimex lectularius) (Bed Bug).
The puncture in the skin made by the bed bug gives rise to an extraordinary amount of severe itching and a burning sensation, and when the skin is sensitive wheals of remarkable size (urticaria ex cimicibus). These eruptions that cause such severe itching are scratched by those attacked, till very soon blood begins to flow, and this generally leads to the formation of a dried crust of blood at the point of eruption.
The diagnosis is not always easy, as urticaria arising in other ways frequently leads to similar vigorous scratching and formation of crusts of dried blood. Men who have some experience in this matter (for example, commercial travellers), when they are attacked by severe itching at night, are in the habit of striking a light and searching in their bed and body-linen for the bugs, in order to be able to hand over the corpora delicti to the landlord if need be. The assumption that the bugs in the East play an actual part in the propagation of tuberculosis and bubonic plague has been proved by investigations made by Nuttall[1069] to be at least very exaggerated if not wholly without foundation. Further investigations may decide how far the bugs participate in the transmission of kala-azar, as is believed by Rogers to take place.
The bed bugs must be exterminated by spraying the chinks and joints in the boards with petroleum and benzine, pulling up the carpets and cleansing the bedsteads. For the treatment of the bite itself the methods recommended as an antidote against insects’ stings in general are suitable: 2 per cent. carbol vaseline (Rosenbach[1070]), thymol dissolved in spirit (1 in 50[1071]), æthrol or deci-æthrol, form-æthrol (manufactured by Dr. Nordlinger, Flörsheim a. /M.), formol[1072] (formol 15 parts, xylol 5 parts, acetone 44 parts, Canada balsam 1 part), with the aid of a pad of wadding placed over the part bitten, lavages with vinegar, citron juice and spirit of salmiac.
Pulex irritans (Human Flea).
The bite of the flea produces a slight discharge of blood about the size of a pin’s head, which rapidly becomes surrounded with a circular area similar to a patch of roseola. The redness fades away after a longer or shorter while (several hours), whilst the discharge of blood is to be seen for one or two days longer. In dirty people the whole body may be covered with such discharges of blood. Individuals with very delicate, sensitive skin, especially small children, show true wheal formation at the site of the bite. In certain cases there develops from one such single bite an urticaria that extends over a large part of the body. The manner by which an irritating substance is introduced into the skin upon biting by the bed bug and also by the flea is clear. The bite is followed by a feeling of itching, which is liable to rob nervous persons of their sleep. Sensitive individuals are upset even by the fleas moving over the surface of the skin during their rest at night.
Treatment consists in extreme cleanliness, capture of the parasites, sprinkling the body and bed-linen with insect powders. The fleas are difficult to remove from barracks, schools and hospitals.
Dermatophilus (Sarcopsylla) penetrans (Sand Flea).
The fertilized females penetrate into the skin with their heads, and here they swell, in consequence of the numerous and growing eggs and larvæ, to a white ball the size of a small pea, on which the head is recognizable only as a small brown point.