Trombiculosis is a seasonal (summer - autumn) skin disease caused by the pathogenic action of small larvae of the Trombiculidae family: Neotrombicula autumnalis. They are also known as augusts, grape harvesters, trombidions, red mullets, red spiders. These larvae are orange in colour and measure between 0.25 and 0.75 mm depending on whether they have eaten or not. They are mainly contaminated by the outdoor environment: lawns, groves, hedges, cedars, etc.
Adults and nymphs do not live on animals but in the environment where they feed on other soil mites. The larvae, on the other hand, are obligate parasites that attach themselves to the skin of animals or humans in a similar way to ticks. The evolutionary cycle lasts from 2 to 12 months but the period during which the augustine larva feeds on the host is 3-4 days.
Most commonly, speckled depilations with crusts, papules (small pimples) and erosions are visible. The larvae sometimes grouped together appear as orange "clusters" of parasites. Pruritus, which manifests itself as biting, licking or scratching, very often accompanies the infestation. The most frequently affected body sites in dogs are the interdigital spaces, the folds of the elbows, the duplication of the auricle (on the auricle) and the interocular region. In cats, the skull region at the base of the ears and the ventral part of the body are added to the classic locations found in dogs.
The location of the lesions and the demonstration of orange hexapod (6-legged) larvae confirm the diagnosis.
The main problem with treatment is frequent reinfestation by a contaminated environment. Lawns, cedars and other shrubs should therefore be avoided as much as possible during the summer season if your dog suffers from this dermatitis.
Repeated topical application of acaricides containing permethrin or fipronil is necessary to kill the Augustate larvae attached to the infected animal and when the inflammation is too severe, oral anti-inflammatory treatments are recommended.
PS: If you are staying in the same environment, the bites may be present. The bites are often observed on the elastic bands of socks, pants, bras, etc. The pruritus can be intense. Contagion from the animal to man is not the source of infestation.
Copyrights Dr Luc Beco