- Helge Riemann, MD
Helge Riemann, MD
- Mid Coast Dermatology, Brunswick, Maine
- Whitney A High, MD
Whitney A High, MD
- Associate Professor of Dermatology and Dermatopathology
- University of Colorado School of Medicine
- Section Editors
- Robert P Dellavalle, MD, PhD, MSPH
Robert P Dellavalle, MD, PhD, MSPH
- Section Editor — General Dermatology
- Professor of Dermatology and Public Health
- University of Colorado School of Medicine
- Colorado School of Public Health
- Chief, Dermatology Service
- US Department of Veterans Affairs
- Eastern Colorado Health Care System
- Ted Rosen, MD
Ted Rosen, MD
- Section Editor — Infections and Infestations
- Professor, Department of Dermatology
- Baylor College of Medicine
Mites are small arachnids that include thousands of species, many of which parasitize animals and plants . In animals and humans, these mites may produce cutaneous lesions, yield allergic reactions, or act as vectors for infectious disease.
The recognition and management of bites from larvae of the Trombiculidae family (also known as "chiggers") will be reviewed here. Synonyms for these organisms include harvest mites, harvest bugs, harvest lice, Mower's mites, and redbugs [2,3]. The term "chigger" should not be confused with "jigger," a term which is typically used to refer to the chigoe flea (tunga penetrans). Other arthropod bites are reviewed separately. (See "Insect bites".)
The adult trombiculid mite is typically 1 to 2 mm in length, with a bright red or red-brown color (picture 1). The life cycle of the mite proceeds through egg, larval, nymphal, and adult stages . Only the larval stage is responsible for chigger bites.
Mite larvae are only 0.15 to 0.3 mm in length (picture 2). After hatching, the larvae reside on leaves or grass stems waiting for an animal or human to pass by. The larvae attach to the skin of the host organism and remain for up to a few days. Subsequently, the larvae drop to the ground to mature into the harmless nymphal and adult stages [1,4].
The nymphal stage is similar to, but smaller than, the adult form. Adults and nymphs live in the soil and feed on plants, other mites and small insects, and insect eggs.
- Brennan JM, Goff ML. Keys to the genera of chiggers of the western hemisphere (acarina: trombiculidae). J Parasitol 1977; 63:554.
- McClain D, Dana AN, Goldenberg G. Mite infestations. Dermatol Ther 2009; 22:327.
- Elston DM. What's eating you? Chiggers. Cutis 2006; 77:350.
- Lane RP, Crosskey RW. Medical Insects and Arachnids, Chapman & Hall, London 1993.
- GASSER R, WYNIGER R. [Distribution and control of Trombiculidae with special reference to Trombicula autumnalis]. Acta Trop 1955; 12:308.
- Toldt K. Neuere Betrachtungen ueber Trombicula-Herde und Tombidiose-Epideien in Mitteleuropa mit besonderer Beruecksichtigung der oesterreichischen Alpenlaender. Ber naturwiss-med Ver Innsbruck 1946; 47:53.
- Clopton RE, Gold RE. Distribution and seasonal and diurnal activity patterns of Eutrombicula alfreddugesi (Acari: Trombiculidae) in a forest edge ecosystem. J Med Entomol 1993; 30:47.
- Farkas J. [Concerning the predilected localisation of the manifestations of trombidiosis. Predilected localisation and its relation to the ways of invasion (author's transl)]. Dermatol Monatsschr 1979; 165:858.
- JONES BM. The penetration of the host tissue by the harvest mite, Trombicul autumnalis Shaw. Parasitology 1950; 40:247.
- Jones JG. Chiggers. Am Fam Physician 1987; 36:149.
- Hase T, Roberts LW, Hildebrandt PK, Cavanaugh DC. Stylostome formation by Leptotrombidium mites (Acari: Trombiculidae). J Parasitol 1978; 64:712.
- Shatrov AB. Stylostome formation in trombiculid mites (Acariformes: Trombiculidae). Exp Appl Acarol 2009; 49:261.
- Potts J. Eradication of ectoparasites in children. How to treat infestations of lice, scabies, and chiggers. Postgrad Med 2001; 110:57.
- Baker EW, Evans TM, Gould DJ, et al. A manual of parasitic mites of medical or economic importance, National Pest Control Association, New York 1956.
- Kampen H. Trombiculiden and Trombidiose. Z Allg Med 2000; 76:392.
- Smith GA, Sharma V, Knapp JF, Shields BJ. The summer penile syndrome: seasonal acute hypersensitivity reaction caused by chigger bites on the penis. Pediatr Emerg Care 1998; 14:116.
- Tilak R, Tilak VW, Yadav JD. Laboratory evaluation of repellents against Leptotrombidium deliense, vector of scrub typhus. Indian J Med Res 2001; 113:98.
- Hanifah AL, Ismail SH, Ming HT. Laboratory evaluation of four commercial repellents against larval Leptotrombidium deliense (Acari: Trombiculidae). Southeast Asian J Trop Med Public Health 2010; 41:1082.
- Fradin MS. Mosquitoes and mosquito repellents: a clinician's guide. Ann Intern Med 1998; 128:931.
- Watt G, Parola P. Scrub typhus and tropical rickettsioses. Curr Opin Infect Dis 2003; 16:429.
- Houck MA, Qin H, Roberts HR. Hantavirus transmission: potential role of ectoparasites. Vector Borne Zoonotic Dis 2001; 1:75.
- Literak I, Stekolnikov AA, Sychra O, et al. Larvae of chigger mites Neotrombicula spp. (Acari: Trombiculidae) exhibited Borrelia but no Anaplasma infections: a field study including birds from the Czech Carpathians as hosts of chiggers. Exp Appl Acarol 2008; 44:307.
- Kampen H, Schöler A, Metzen M, et al. Neotrombicula autumnalis (Acari, Trombiculidae) as a vector for Borrelia burgdorferi sensu lato? Exp Appl Acarol 2004; 33:93.
- Fernández-Soto P, Pérez-Sánchez R, Encinas-Grandes A. Molecular detection of Ehrlichia phagocytophila genogroup organisms in larvae of Neotrombicula autumnalis (Acari: Trombiculidae) captured in Spain. J Parasitol 2001; 87:1482.