Rodent mite dermatitis

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Rodent mite dermatitis
Other names: Rat mite dermatitis
Young child with skin injuries caused by bites of the Tropical rat mite- Ornithonyssus bacoti
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Rodent mite dermatitis (also known as rat mite dermatitis) is an often unrecognized ectoparasitosis occurring after human contact with haematophagous mesostigmatid mites that infest rodents, such as house mice,[1] rats[2] and hamsters.[3] The condition is associated with the tropical rat mite (Ornithonyssus bacoti), spiny rat mite (Laelaps echidnina) and house mouse mite (Liponyssoides sanguineus)[4] which opportunistically feed on humans. Rodent mites are capable of surviving for long periods without feeding and travelling long distances when seeking hosts.[4] Cases have been reported in homes, libraries,[5] hospitals[6] and care homes.[7] A similar condition, known as gamasoidosis, is caused by avian mites.[8]

Symptoms and signs

Rodent mite bites leave multiple groups or individual small itchy papules (around 1–2 mm in diameter)[7] on the skin (papular urticaria).[9][10] These are found mostly "on the upper extremities, neck, upper trunk and face".[7]


Diagnosis requires species identification of the parasite, which will be likely to be found in the environment of its host rather than on the hosts’ skin.[10] Rodent mites are very small, for O. bacoti "female mites reach a size between 0.75 and 1.40 mm, males are a little smaller".[7]


The original rodent host of the mites must be located and eradicated,[11] and their nests removed.[12] Steps should also be taken to prevent future infestations, such as by blocking the rodents means of entry into the building. The patient's environment should then be treated,[10] using both non-residual and residual insecticides, mites crawling in the open can be removed by vacuuming or with a cloth moistened with alcohol.[12]

Bites can be treated with antihistamines and corticosteroids, to relieve the associated itching and allergic reactions.[7]


L. sanguineus has been implicated in the spread of Rickettsialpox.[13]

See also


  1. Reeves, Will K.; Cobb, Kristin D. (2005-07-01). "Ectoparasites of House Mice (Mus musculus) from Pet Stores in South Carolina, U.S.A". Comparative Parasitology. 72 (2): 193–195. doi:10.1654/4178. ISSN 1525-2647. S2CID 85650971.
  2. Engel, Peter M.; Welzel, J.; Maass, M.; Schramm, U.; Wolff, H. H. (1998). "Tropical Rat Mite Dermatitis: Case Report and Review". Clinical Infectious Diseases. 27 (6): 1465–1469. doi:10.1086/515016. ISSN 1058-4838. PMID 9868661.
  3. Creel, Naomi B.; Crowe, Mark A.; Mullen, Gary R. (2003). "Pet hamsters as a source of rat mite dermatitis". Cutis. 71 (6): 457–461. ISSN 0011-4162. PMID 12839256.
  4. 4.0 4.1 Watson, J. (2008-01-01). "New Building, Old Parasite: Mesostigmatid Mites--An Ever-Present Threat to Barrier Rodent Facilities". ILAR Journal. 49 (3): 303–309. doi:10.1093/ilar.49.3.303. ISSN 1084-2020. PMC 7108606. PMID 18506063.
  5. Chung, Sang Lip; Hwang, Sung Joo; Kwon, Soon Baek; Kim, Do Won; Jun, Jae Bok; Cho, Baik Kee (1998). "Outbreak of rat mite dermatitis in medical students". International Journal of Dermatology. 37 (8): 591–594. doi:10.1046/j.1365-4362.1998.00558.x. ISSN 0011-9059. PMID 9732004. S2CID 34760181.
  6. Haggard, Carl N. (1955-03-01). "Rat Mite Dermatitis in Children". Pediatrics. 15 (3): 322–324. doi:10.1542/peds.15.3.322. ISSN 0031-4005. PMID 14356805. S2CID 32691957. Archived from the original on 2017-08-28. Retrieved 2023-03-21.
  7. 7.0 7.1 7.2 7.3 7.4 Baumstark, J.; Beck, W.; Hofmann, H. (2007). "Outbreak of Tropical Rat Mite (Ornithonyssus bacoti) Dermatitis in a Home for Disabled Persons" (PDF). Dermatology. 215 (1): 66–68. doi:10.1159/000102037. ISSN 1018-8665. PMID 17587843. S2CID 3124223. Archived (PDF) from the original on 2017-08-12. Retrieved 2023-03-21.
  8. Kowalska, M.; Kupis, B. (1976). "Gamasoidosis (gamasidiosis)-not infrequent skin reactions, frequently unrecognized". Polish Medical Sciences and History Bulletin. 15–16 (4): 391–394. ISSN 0301-0236. PMID 826895.
  9. Engel, P. M.; Welzel, J.; Maass, M.; Schramm, U.; Wolff, H. H. (1998). "Tropical rat mite dermatitis: case report and review". Clinical Infectious Diseases. 27 (6): 1465–1469. doi:10.1086/515016. ISSN 1058-4838. PMID 9868661.
  10. 10.0 10.1 10.2 Beck, W. (2007-11-01). "Tropical Rat Mites as newly emerging disease pathogens in rodents and man". Travel Medicine and Infectious Disease. 5 (6): 403. doi:10.1016/j.tmaid.2007.09.016. ISSN 1477-8939.
  11. Fox, James G. (1982-09-01). "Outbreak of Tropical Rat Mite Dermatitis in Laboratory Personnel". Archives of Dermatology. 118 (9): 676–8. doi:10.1001/archderm.1982.01650210056019. ISSN 0003-987X. PMID 7114872.
  12. 12.0 12.1 "Parasitic Mites of Humans | Entomology". Archived from the original on 2017-06-12. Retrieved 2018-06-05.
  13. Azad, A. F.; Beard, C. B. (1998). "Rickettsial pathogens and their arthropod vectors". Emerging Infectious Diseases. 4 (2): 179–186. doi:10.3201/eid0402.980205. PMC 2640117. PMID 9621188.