Zoonotic Hookworm Infection and Cutaneous Larva Migrans
Amanda Truong, MD, PhD, provides her perspective on diagnosis, treatment, and environmental factors, considering her involvement in a recent human case.
Zoonotic hookworm infection, CLM.
Image credits: CDC
Zoonotic hookworm infection in humans, commonly presenting as cutaneous larva migrans (CLM), occurs when hookworm larvae, typically from animals like dogs or cats, penetrate human skin. Primarily caused by Ancylostoma braziliense, the larvae migrate through the epidermis, leading to raised, erythematous tracks that often cause intense itching. While CLM usually resolves on its own, severe cases may require medication. Diagnosis is clinical, based on the characteristic skin lesions and exposure history, particularly in individuals with recent contact with contaminated soil or sand. In rare cases, larvae can migrate to internal organs, causing complications such as eosinophilic enteritis or ocular larva migrans.1
In an email Q&A with Amanda Truong, MD, PhD, a physician scientist at UCLA specializing in dermatology, we discussed CLM. Trumong co-authored the case of a 19-year-old beach lifeguard from Southern California who presented with asymptomatic, erythematous, raised, serpiginous lesions on the neck, published in NEJM.2
Contagion: Can you describe the clinical presentation of CLM’s, and how do you distinguish it from other dermatologic conditions?
Truong: Cutaneous larva migrans (CLM) typically presents as an itchy, serpiginous (wavy, snake-like) rash caused by the larvae of hookworms burrowing into the skin. The classic presentation is a patient who recently walked barefoot on the beach and develops this rash on their feet or ankles, usually about a week later. The key distinguishing features are the itching and the migratory, winding path of the rash as the larvae move under the skin
Contagion: What diagnostic methods are most effective in confirming CLM, and are there any challenges in making the diagnosis early?
Truong: Diagnosis is primarily clinical, based on the patient's history (such as recent exposure to sand or soil where infected animals may have defecated) and the characteristic appearance of the rash. Though the rash typically appears days to weeks after inoculation, diagnosing CLM prior to the onset of symptoms can be challenging.
Contagion: How do environmental factors, such as geography or animal populations, influence the incidence of CLM, and what areas are most at risk?
Truong: Environmental factors play a large role in CLM incidence. The hookworm larvae are typically transmitted to human skin through contaminated sane or soil, often from animal feces of dogs and cats. It is most commonly seen in tropical climates, especially in areas with free-roaming animals and poor sanitation.
Contagion: What are the current treatment options for CLM, and are there any emerging therapies or challenges in managing the infection?
Truong: CLM is usually treated with anti-helminthic medications, such as albendazole and ivermectin. There are no significant emerging therapies at this time, but challenges can arise in cases where secondary bacterial infections complicate the rash.
Contagion: What role do veterinarians and pet owners play in preventing the transmission of hookworm larvae to humans, and what public health measures can help reduce the incidence of CLM?
Truong: Veterinarians and pet owners play a crucial role in preventing the transmission of hookworm larvae by ensuring regular deworming of pets and proper disposal of animal waste, particularly in areas where CLM is more common. Public health initiatives should focus on education—particularly for locals and tourists—on the importance of wearing shoes on beaches, using towels or blankets when sitting in sand, deworming stray animals, and improving beach sanitation.
Contagion: What are the potential complications or long-term effects if CLM is left untreated, and how can clinicians best manage these cases?
Truong: Fortunately, CLM is self-limiting and responds well to a short course of anti-helminthics. Because the skin barrier is compromised, there is a possibility for the rash to become secondarily infected with bacteria, in which case topical or oral antibiotics may be necessary.
Zoonotic hookworm infection, particularly CLM, highlights the importance of accurate diagnosis, environmental awareness, and early intervention. Most cases resolve naturally, but severe cases require medical attention. Truong emphasizes the need for prevention through pet care and public health initiatives, along with proper management of complications.
