OBSERVATION Multiple Pruritic Papules From Lone Star Larvae Bites

Emily J. Fisher, MD; Jun Mo, MD; Anne W. Lucky, MD

Background: are the second most common vec- was treated with permethrin cream and the lesions re- tors of human infectious diseases in the world. In addi- solved over the following 3 weeks without sequelae. The tion to their role as vectors, ticks and their larvae can also organism was later identified as the larva of Amblyomma produce primary skin manifestations. Infestation by the species, the lone star tick. larvae of ticks is not commonly recognized, with only 3 cases reported in the literature. The presence of mul- Conclusions: Multiple pruritic papules can pose a di- tiple lesions and partially burrowed 6-legged tick larvae agnostic challenge. The patient described herein had an can present a diagnostic challenge for clinicians. unusually large number of pruritic papules as well as tick larvae present on her skin. Recognition of lone star tick Observation: We describe a 51-year-old healthy woman larvae as a cause of multiple bites may be helpful in simi- who presented to our clinic with multiple erythematous lar cases. papules and partially burrowed organisms 5 days after exposure to a wooded area in southern Kentucky. She Arch Dermatol. 2006;142:491-494

ATIENTS WITH MULTIPLE PRU- acteristic clinical and diagnostic features of ritic papules that appear to be infestation by larvae of Amblyomma species bitespresentachallengetothe and may help clinicians make similar di- clinician. We present a case of agnoses in the future. a healthy 51-year-old woman whowasbittenbymultiplelarvaeofthetick, P REPORT OF A CASE Amblyomma species, most likely A ameri- canum or the lone star tick. Ticks have been recognizedashumanparasitesforthousands A 51-year-old white woman presented with of years and are the second most common multiple, diffuse, intensely pruritic pap- vector of human infectious disease after ules and papulovesicles (Figure 1). Five mosquitos.1 Their role in the transmission days prior to her presentation, the pa- of several human infectious diseases has tient was boating on a lake in southern Kentucky. On 2 occasions, she had dis- For editorial comment robed in a wooded area near the lake, leav- ing her clothes on the ground for several see page 497 minutes before redressing. One day after the second time she undressed, the pa- been known since the beginning of the 20th tient noted the onset of an erythematous century.1 In particular, Amblyomma species pruritic rash that progressed with addi- have been identified as the vector for tional lesions over the next few days. several human diseases including Rocky She visited several physicians in the fol- Mountain , , ehrlichio- lowing days who variously diagnosed infes- sis, , and African tick bite fever tationswith“no-see-ums”(forwhichshewas Author Affiliations: Division of via salivary secretions. In addition to being prescribed cetirizine hydrochloride [Zyrtec; Pediatric Dermatology vectors for human diseases, ticks can cause Pfizer US, New York, NY] and a 5-day course (Drs Fisher and Lucky) and severalprimarydermatologicmanifestations of prednisone), bedbugs, and finally pubic Department of Pathology including erythematous papules, skin hem- lice (for which she was given a prescription (Dr Mo), Cincinnati Children’s Hospital Medical Center, and orrhages, papular urticaria, diffuse derma- of 5% permethrin cream). Despite numer- Department of Dermatology, titis, necrotic ulcers, prurigo, erythema ousshowersandscrubs,therashprogressed, The University of Cincinnati migrans–like rash, and patchy alopecia, but and the patient began to note the presence School of Medicine (Drs Fisher reports of primary infestations are rare.2-5 of tiny dark “bugs” attached to her skin in and Lucky), Cincinnati, Ohio. The present report summarizes the char- the centers of many of the papules.

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021 Figure 1. Multiple erythematous papules on a 51-year-old woman seen 5 days after her exposure to wooded area.

Figure 3. Amblyomma species, microscopic view, showing 6-legged larval A B form.

COMMENT

Ticks are obligate blood-sucking arthropods that para- sitize every class of vertebrate in almost every region of the world. They are currently considered to be second only to mosquitoes as vectors of human infectious dis- eases in the world.1 The life cycle of most hard ticks requires 2 years for completion and includes the egg, the 6-legged larva or Figure 2. Organism partially burrowed in the skin. A, The organism appears “seed tick,” the 8-legged immature nymph, and the as a dark spot. B, Close-up view of the organism on the skin, later identified 8-legged reproductively mature adult. All stages except as Amblyomma species larva, the lone star tick. the egg require a blood meal for morphogenesis.6,7 The larvae emerge from eggs deposited on the ground and then She presented to our dermatology clinic for further crawl up grasses and other low vegetation where they can recommendations before using the permethrin cream. In easily attach to passing animals or humans.2 The tick clings the clinic, we found hundreds of red, blanching papules to hair or clothing, waits until the host is at rest, moves and papulovesicles on her trunk and extremities, espe- to an appropriate exposed area of the host’s body, and cially in areas that had been under her clothing. On close then bites. inspection, we found dark, 1-mm organisms in the cen- It appears that this patient must have undressed near ter of many of the papules. Under magnification, these a nest of newly hatched tick larvae that were attracted to were determined to be bugs of unknown type whose heads her clothing and attached themselves before transfer- were partially burrowed under the skin (Figure 2). Sev- ring to her skin when she redressed. Ticks inject an an- eral of the organisms were removed with forceps and vi- esthetic similar to lidocaine, which usually makes their sualized in mineral oil under the microscope; they were bites painless. A tick may spend up to 24 hours on the rotund, 6-legged organisms (Figure 3). host before biting and then feed for 2 hours to 7 days be- The patient was instructed to complete a single overnight fore dropping off.8 After completion of a blood meal at 1 application of 5% permethrin cream and try to scrub off the site, the larva typically drops to the ground where it molts organisms the next morning. The initial diagnosis was in- to become a nymph.3 The larval and nymphal stages are festation by chigger , but because of the unusual na- so small they often are not seen until they have fully en- ture of the presentation, including the large size and num- gorged with blood. This may account for the patient not ber of organisms and the fact that the organisms were still noticing the ticks until the fourth or fifth day of her in- attached and burrowed, this diagnosis was questioned. festation. Sample organisms were sent for definitive identifica- For most tick-borne diseases, it appears that the tick tion to the C. Wayne Ellett Plant and Pest Diagnostic Cen- must remain attached for 24 to 48 hours before disease ter of Ohio State University, Columbus, and found to be transmission occurs.9 Among the 13 genera of Ixodidae, the larvae of Amblyomma species, most likely A ameri- 3 are known to transmit disease to humans in the United canum, the lone star tick. The patient’s pruritus began States: Amblyomma, Dermacentor, and Ixodes.7 All stages to resolve approximately 2 days after application of the of Amblyomma except the egg are capable of transmit- permethrin cream, and the erythematous papules gradu- ting disease.2,3 ally resolved over the next 3 weeks. She has not had any Amblyomma americanum is the most common spe- further complications. cies of Amblyomma found in the United States. It is named

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021 the lone star tick due to the prominent white dot on the NH). In a study comparing these 3 tools with tweezers, back of the adult female and is abundant in the south cen- it was found that all of these tools were more effective tral and southeastern United States. Amblyomma ameri- than tweezers in removing nymph-stage ticks.14 canum and Amblyomma cajennense ticks will feed on small There are no data to indicate that prophylactic treat- or large mammals during any stage of their life cycle and ment with after a tick bite reduces the risk of are commonly found on white-tailed deer.2,10 They are disease transmission in all cases. A recent randomized known to transmit several human diseases including ehrli- trial showed that a single 200-mg dose of chiosis () in the mid-Atlantic, south administered within 72 hours after a recognized Ixodes central, southeastern, and western (California) states; tu- scapularis bite had an efficacy of 87% in preventing ery- laremia () in the southeastern and thema migrans. The number needed to treat to prevent south central states; and, less commonly, Rocky Moun- 1 case of erythema migrans was 36 among people with tain spotted fever ( rickettsi) and Q fever (Coxi- any I scapularis bite and 12 among people with bites from ella burnetii). Amblyomma americanum is a rare cause of engorged nymphal I scapularis.15 The possible effects of tick paralysis.6 In the past several years, A americanum prophylactic treatment on other infections transmitted has been shown to be the vector for an erythema migrans– by deer ticks and on strains of Borrelia in Europe and like rash illness termed “southern tick-associated rash ill- Asia, as well as its use to prevent in chil- ness” (STARI) caused by Borrelia lonestari.11-13 dren, have not been evaluated. Because of the low cost, Ticks can also cause problems in the host without safety, simplicity, and efficacy, some authors argue that transmitting infection. Uncomplicated bites can be pain- a single dose of doxycycline is recommended for adults ful and leave a red puncture wound that takes 1 to 2 weeks who live in areas where Lyme disease is endemic and who to heal. Rarely, bites cause a delayed hypersensitivity re- seek treatment for a bite from an engorged I scapu- action, with fever, pruritus, and urticaria. A granuloma laris.15 These same authors state that bites from Derma- can develop if a tick is removed improperly.8 Other re- centor variabilis and A americanum do not require pro- ports describe prurigo lesions, skin hemorrhages, papu- phylactic treatment. Testing for the presence of antibodies lar urticaria, diffuse dermatitis (papules, vesicles, and bul- against tick-borne bacteria at presentation and at 3 to 6 lae), necrotic ulcers, and patchy alopecia.4,5 The severity weeks and treating if there is clinical or serologic evi- of the skin reaction to tick feeding may depend on sev- dence of infection is not recommended because of the eral variables, including duration of feeding, size of the low sensitivity, low positive predictive value, and the cost mouthparts, type of tick secretions (eg, saliva or ce- of the tests. Clinicians must observe and treat only if a ment), changes in secretion during feeding, previous ex- disease occurs.1 posure of the host to the tick or related species, and al- Tick bites are best prevented by avoiding tick- lergic reactions of the host.4 infested areas. When this is not possible, tick bites may Only 3 other cases of primary infestation by A ameri- be prevented by wearing long pants that are tucked into canum larvae have been reported. Two cases were in chil- boots. In addition, the application of a topical DEET (N,N- dren and presented as asymptomatic clusters of small Am- diethyl-m-toluamide) repellent to exposed skin and treat- blyomma larvae on the neck, back, and scrotum. The third ment of clothing with permethrin can prevent tick bites. case was an adult woman who presented with multiple This system is currently used by the US Army and nu- pruritic erythematous macules and plaques on the trunk merous armies throughout the world to protect their sol- and thighs with burrowed pinhead-sized organisms, simi- diers.1 It produces nearly 100% protection. When used lar to our case.2,3 alone, DEET provides greater than 90% protection for When patients present with attached ticks, removal up to 2.7 hours against A americanum.16,17 The optimal may be difficult. Most authors recommend removal with concentration of DEET to use for maximum protection blunt forceps (tweezers). The tick should be grasped close is 15% to 33%. Its efficacy plateaus at a concentration of to the skin and steady pressure applied, pulling the tick 30%, which is the maximum concentration currently rec- straight out perpendicular to the skin. A twisting mo- ommended for infants and children.6,18 Treating cloth- tion can cause the head to separate from the body and ing with permethrin can be accomplished through a pres- potentially remain in the bite wound. The area should surized spray formulation (Duranon; [Sawyer Products/ be immediately cleansed with a disinfectant, according Clouston, Tampa, Fla], Sawyers [Sawyer Products], Repel to some authors.1,9 Punch or shave biopsy is an alterna- Permanone [Spectrum Brands, St Louis, Mo]) or via im- tive approach. After the tick is isolated, some authors rec- pregnation. It can be used in any age group and remains ommend storing the arthropod at −20°C in the event that effective for several weeks and through several weekly the patient develops a disease.1,6 Suffocating ticks with washings.1 When used alone, permethrin-treated cloth- agents such as petrolatum, sun tan oil, or fingernail pol- ing kills or disables 79%to 100% of A americanum ticks ish may take several hours to cause the tick to with- for up to several hours.19,20 draw, allowing more time for possible pathogen trans- In conclusion, ticks are the second most common vec- mission.9 Burning the tick with a match or other hot tor of human infectious disease in the world. In addi- devices should be avoided because this might cause the tion to their role as a disease vector, ticks can also pro- tick to regurgitate thus increasing the risk of transmit- duce primary skin disorders. The 6-legged larvae can also ting disease.6 Several commercial tick removal tools are bite, which may make a correct diagnosis difficult if the available to consumers. These include Tick Nipper (Saw- clinician is not aware of the development of ticks from yer Products, Tampa, Fla), Pro-Tick Remedy (SCS Ltd, this 6-legged organism to the adult with 8 legs. The pa- Lake Ariel, Pa), and Ticked Off (Ticked Off Inc, Dover, tient described in this report was a diagnostic challenge

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/24/2021 because of the unusually large number of bites and lar- 7. Spach DH, Liles WC, Campbell GL, Quick R, Anderson D, Fritsche T. Tick-borne vae present on her skin and the vesicular reaction that diseases in the United States. N Engl J Med. 1993;329:936-947. 8. Middleton DB. Tick-borne Infections. Postgrad Med. 1994;95:131-139. ensued. Recognition of lone star tick larvae as a cause of 9. Moody EK, Barker R, White J, Crutcher J. Ticks and tick-borne diseases in Oklahoma. pruritic papules may be helpful in similar cases. J Okla State Med Assoc. 1998;91:438-445. 10. Steiert JG, Gilfoy F. Infection rates of Amblyomma americanum and Dermacen- Accepted for Publication: August 30, 2005. tor variabilis by Ehrlichia chaffeensis and in southwest Missouri. Vector Borne Zoonotic Dis. 2002;2:53-60. Correspondence: Emily J. Fisher, MD, Divison of Pedi- 11. Burkot TR, Mullen GR, Anderson R, Schneider BS, Happ CM, Zeidner NS. Bor- atric Dermatology, University of Cincinnati School of relia lonestari DNA in Adult Amblyomma americanum ticks, Alabama. Emerg In- Medicine, 234 Goodman Ave, Pavilion A, Cincinnati, OH fect Dis. 2001;7:471-473. 45267 ([email protected]). 12. Kirkland KB, Klimko TB, Meriwether RA, et al. Erythema migrans-like rash ill- ness at a camp in North Carolina: a new tick-borne disease? Arch Intern Med. Author Contributions: Study concept and design: Fisher 1997;157:2635-2641. and Lucky. Acquisition of data: Fisher and Mo. Drafting 13. Varela AS, Luttrell MP, Howerth EW, et al. First culture isolation of Borellia lonestari, of the manuscript: Fisher. Critical revision of the manu- putative agent of southern tick-associated rash illness. J Clin Microbiol. 2004; script for important intellectual content: Mo and Lucky. Ad- 42:1163-1169. ministrative, technical, and material support: Fisher and 14. Stewart RL, Burgdorfer W, Needham G. Evaluation of three commercial tick re- moval tools. Wilderness Environ Med. 1998;9:137-142. Mo. Study supervision: Lucky. 15. Hayes EB, Piesman J. How can we prevent Lyme disease? N Engl J Med. 2003; Financial Disclosure: None. 348:2424-2430. 16. Solberg VB, Klein TA, McPherson KR, Bradford BA, Burge JR, Wirtz RA. Field evaluation of DEET and a piperidine repellent against Amblyomma americanum. REFERENCES J Med Entomol. 1995;32:870-875. 17. Schreck CE, Fish D, McGovern TP. Activity of repellents applied to skin for pro- 1. Parola P, Raoult D. Ticks and tickborne bacterial diseases in humans: an emerg- tection against Amblyomma americanum and Ixodes scapularis ticks (Acari: ing infectious threat. Clin Infect Dis. 2001;32:897-928. Ixodidae). J Am Mosq Control Assoc. 1995;11:136-140. 2. Duckworth PF, Hayden G, Reed C. Human infestation by Amblyomma america- 18. American Academy of Pediatrics. Follow safety precautions when using DEET num larvae (“seed ticks”). South Med J. 1985;78:751-753. on children. 2003. Available at http://aapnews.aappublicatons.org/cgi/content 3. Jones BE. Human “seed tick” infestation. Arch Dermatol. 1981;117:812-814. /full/e200399v1. Accessed February 9, 2006. 4. Krinsky WL. Dermatoses associated with the bites of mites and ticks (Ar- 19. Evans SR, Korch G, Lawson M. Comparative field evaluation of permethrin and thropoda: Acari). Int J Dermatol. 1983;22:75-91. deet-treated military uniforms for personal protection against ticks (Acari). J Med 5. Yesudian P, Thambiah A. Persistent papules after tick-bites. Dermatologica. 1973; Entomol. 1990;27:829-834. 147:214-218. 20. Mount GA, Snoddy EL. Pressurized sprays of permethrin and DEET on clothing 6. Singh-Behl D, La Rosa S, Tomecki K. Tick-borne infections. Dermatol Clin. 2003; for personal protection against the lone star tick and the american dog tick (Acari: 21:237-244. Ixodidiae). J Econ Entomol. 1983;76:529-531.

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