Trombiculosis (Chigger Infestation)

Share me

Table of Contents

Introduction

Trombiculosis is a skin condition caused by the larval stages of many types of mites, particularly those from the genus Trombicula. It is sometimes referred to as chigger infestation or harvest mite infestation. Fields, woodlands, and grassy places are common habitats for these mites and they are common in warm and humid areas. The mites typically range in size from 0.2 to 0.4 millimeters and are hardly visible to the naked eye.

Trombiculid mites may attach themselves to the skin when a person comes into contact with the soil or vegetation where they live. Once they have a hold of the skin, they pierce it with their mouthparts to consume tissue fluids. Trombiculid mite bites typically occur in groups or clusters and are frequently discovered in places where clothing presses closely against the skin, such as the waistline, sock lines, or skin folds. Because trombiculosis is a self-limiting disorder, it typically goes away on its own within a few weeks without any kind of medical attention.

Incidence

Geographical location and environmental factors can affect the prevalence of trombiculosis, or chigger infestation.
The condition is more frequently observed in areas where trombiculid mites are abundant.
Trombiculosis is frequently underreported and is not generally recognized as a condition that needs to be reported; therefore, precise incidence rates might not be easily accessible.
Trombiculosis is known to be common in many regions of the world, including North and South America, Europe, Asia, and Africa,
It’s vital to remember that seasonal variations and factors in the environment that support the presence of chigger mites can affect the occurrence of trombiculosis.
For instance, trombiculosis cases may increase in the summer, when chigger activity is highest.

Incubation Period of Trombiculosis

The incubation period normally ranges from a few hours to a few days.

Causes of Trombiculosis

The bite of trombiculid mites, Neotrombicula autumnalis, causes Trombiculosis.

Risk Factors of Trombiculosis

Trombiculosis can be made more likely by several circumstances such as:

Geographical location: Trombiculid mites are more common in some areas, especially those with hot and muggy weather.
Outdoor activities: Taking part in outdoor activities that require coming into contact with grassy or woody regions, such as hiking, camping, gardening, or playing sports, can raise your risk of developing trombiculosis.
Direct contact with plants, tall grass, bushes, or soil: Direct contact with plants, tall grass, bushes, or soil patches where trombiculid mites are present can increase the chance of infestation.
Clothing Options: Chiggers frequently latch onto places where clothing is tightly fastened to the skin, such as waistbands, sock lines, and shoelaces.
Personal habits: The likelihood of getting chigger bites can be increased by sitting or sleeping on the ground in infested regions, wearing clothing that exposes a lot of skin, or failing to take preventative measures such as using insect repellents.

Mode of Transmission of Trombiculosis

The mode of transmission of trombiculosis is direct contact with Trombicula mites. It is not possible to spread from person to person.

Signs and Symptoms of Trombiculosis

The bite goes unnoticed at the initial phase, but within one to three hours, symptoms appear in the area of the bite. The most typical signs and symptoms of trombiculosis are as follows:

Intense itching
Skin Redness and swelling
Rashes (tiny, red papules or spots)
Blistering (fluid-filled under the skin)
Secondary bacterial infections due to scratch

Pathophysiology of Trombiculosis

When a human comes into contact with soil or a plant, the mites’ larvae latch onto the skin. They frequently cling to places like the waistline, sock lines, or skin folds where clothing presses closely against the skin. Larvae pierce the skin with their mouthparts and start consuming the fluids of the tissues.

They inject saliva into the skin as they feed. Digestive enzymes, which are crucial for dissolving skin cells and promoting eating, are among the many compounds found in saliva. These enzymes aid in the host’s tissue fluids being broken down by the mites. The host’s body mounts an immunological response in reaction to the trombiculid mite saliva entering the skin. The immune system detects the foreign nature of the mite saliva and launches an inflammatory response to counter the perceived threat. Histamine, cytokines, and chemokines are among the inflammatory mediators that are released by the immune response in the skin.

These compounds expand blood vessels (vasodilation) and make blood vessels in the afflicted area more permeable. The inflammatory response causes trombiculosis-specific symptoms. Itching, redness, and a rash appear as a result of histamine and other mediators being released.
Trombiculosis is typically a self-limiting condition, it gets better on its own with time. After finishing their feeding cycle, the mites fall off the skin as the immune response finally wanes. The signs disappear as the skin begins to heal, and the symptoms gradually subside.

Diagnosis of Trombiculosis

Trombiculosis is often diagnosed based on a combination of the patient’s clinical symptoms, exposure history, and physical exam. To diagnose trombiculosis, no particular imaging or laboratory tests are often employed. In general, the diagnosis includes the following steps:

History

Most recent outdoor activities like any potential exposure to trombiculid mites in grassy or wooded areas
Exposure area
Asking symptoms such as itchiness, rash, and redness in typical body parts
Any other people who have complained of the same symptoms

Physical examination

Examination of injured skin
Finding signs such as rashes, redness, grouped or clustered red papules, welts, or tiny blisters

Video dermatoscopy

Video dermatoscopy is a non-invasive procedure used to examine cutaneous skin lesions.
It can detect a strong fluorescent orange-reddish color of the mite’s larva presenting on the skin.

Treatment/Management of Trombiculosis

The goal of trombiculosis, or chigger infestation, treatment is to reduce symptoms and protect against further problems. The following methods are frequently employed:

Symptomatic relief

Itch Reduction: Topical corticosteroids or over-the-counter antihistamines such as diphenhydramine (Benadryl) can help soothe irritation and lessen inflammation. Hydrocortisone cream or calamine lotion may also be helpful.
Pain relief: Ibuprofen and other nonsteroidal anti-inflammatory medicines (NSAIDs) can be used to treat the pain and inflammation brought on by trombiculosis.

Care and hygiene

Gentle Cleaning: Washing the affected areas with moderate soap and water regularly aids in removing mite remains, lowering the risk of infection, and accelerating healing. Avoid excessively cleaning the skin, as this can make the irritation worse.
Avoid too much scratching: Scratching aggravates skin irritation, raises the possibility of secondary infections, and prolongs healing time. To reduce skin damage, avoid over-scratching and maintain neat fingernails.

Prevent secondary infections

It is best to get medical help if symptoms of infection such as increased redness, swelling, warmth, discomfort, or pus manifest.
If a secondary bacterial infection is present, the doctor may advise antibiotic treatment.

Complications of Trombiculosis

Trombiculosis rarely causes complications. However, some elements or behaviors may raise the likelihood of difficulties. The following are a few probable trombiculosis complications:

Secondary bacterial infections: Impetigo, cellulitis, dermatitis
Allergic Reactions
Psychological Effect: sleep difficulties, irritability, and emotional anguish.

Prevention of Trombiculosis

The prevention of trombiculosis is possible by minimizing contact with trombiculid mites and reducing the bite risk. Some preventive measures are:

Keep away from high-risk areas: Avoid places with tall grass, dense vegetation, and rodent activity, which are known to have high populations of trombiculid mites.
Put on protective clothing: When going to locations where chiggers may be prevalent, put on long-sleeved shirts, long pants, and closed-toe shoes. To block the mites from entering, tuck your slacks into your socks and wrap adhesive tape around your ankles and wrists.
Use insect repellents: Follow the package recommendations for applying insect repellents with DEET (N,N-diethyl-meta-toluamide) or permethrin to exposed skin and clothes. These
Take a shower and change your clothes: After spending time in a location that may be chigger-infested, quickly wash your clothes and take a shower to remove stuck chiggers.
Treat outdoor gear and dogs: Ticks and fleas can also transport chiggers, so if your dog spend time outside, check them regularly. To lessen the possibility of getting chiggers into your home, you should also inspect and treat outside equipment, such as camping gear or gardening tools.
Environmental actions: Keep lawns neatly mowed, remove brush, and trim back overgrown vegetation to reduce the occurrence of trombiculid mites in outdoor spaces .Be mindful of high-risk regions like long grass, dense undergrowth, or rodent habitats, and limit your exposure to those areas.

Prognosis

Trombiculosis typically has a positive prognosis.
The body’s immune response clears the infestation, and mites usually go away on their own.
The healing process could be slowed down by frequent scratching, which can harm the skin and raise the chance of secondary infections.
Secondary bacterial infections might develop if you scratch chigger bites excessively or break the skin. These infections may require medical attention if left untreated since they might lead to problems.

Summary

Trombiculosis is a skin ailment brought on by the bites of trombiculid mites, usually known as chiggers. The mites are prevalent in grassy or wooded environments and are most active during the warm months. The mites cling to the skin and inject saliva, which irritates the skin and produces itching, redness, and swelling. Direct contact with the mites in their environment is the mode of transmission. Outdoor activities in high-risk areas, such as hiking or camping, are risk factors for trombiculosis.

Trombiculosis is characterized by severe itching, red papules or welts, and perhaps blisters. The clinical presentation, history, and physical examination serve as the mainstays of the diagnosis. Although trombiculosis complications are uncommon, they can include subsequent bacterial infections and allergic responses. Preventive measures include avoiding high-risk areas, using safety gear, applying insect repellents, and maintaining excellent hygiene. Trombiculosis typically resolves on its own within a few weeks and does not require any special medical care.

Also Read:

References

Alexander, L., & Buckley, C. J. (2022, Jan). Chigger Bites. StatPearls Publishing Retrieved on 2023, June 17 from https://www.ncbi.nlm.nih.gov/books/NBK538528/
Caputo, V., Santi, F., Cascio, A., Trizzino, M., & Colomba, C. (2018). Trombiculiasis: an underreported ectoparasitosis in Sicily. Le infezioni in medicina, 26(1), 77–80. PMID: 29525801
Ramondetta, A., Ribero, S., Peano, A., Quaglino, P., & Broganelli, P. (2020). In Vivo Observation of Trombiculosis with Fluorescence-Advanced Videodermatoscopy. Emerging infectious diseases, 26(8), 1904–1905. https://doi.org/10.3201/eid2608.200077
Cleveland Clinic. (2022, June 7). Chigger bites. Retrieved on 2023, June 16 from https://my.clevelandclinic.org/health/diseases/23267-chigger-bites
Salvadori, C., Formenti, N., Trogu, T., Lanfranchi, P., Rossi, L., Citterio, C., Obber, F., & Poli, A. (2019). Pathology and distribution of trombiculosis in Northern Chamois (Rupicapra rupicapra rupicapra) in the Italian Alps. Journal of wildlife diseases, 55(1), 183-188. DOI: 10.7589/2018-01-020