Reactivation of Strongyloides stercoralis in patients with SARS-CoV-2 pneumonia receiving dexamethasone

To the Editor:

Low-dose dexamethasone therapy has been established as one of the mainstays in the management of hospitalised patients with SARS-CoV-2 pneumonia requiring oxygen therapy.¹ However, the risk of reactivation of Strongyloides stercoralis (S. stercoralis) after 10 days of treatment with low-dose dexamethasone at 6 mg/day is not well defined.

We report two cases of cutaneous reactivation of chronic S. stercoralis infection with the appearance of larva currens in patients hospitalised for SARS-CoV-2 pneumonia and treated with dexamethasone.

A 44-year-old man from Bolivia, resident in Spain for 17 years, with a history of smoking, hypertension and obesity, was admitted for severe bilateral SARS-CoV-2 pneumonia requiring high-flow oxygen therapy and dexamethasone 6 mg/day. On the seventh day, the patient developed generalised pruritus and a new linear urticarial lesion on the abdomen. Suspecting possible larva currens, serology for S. stercoralis IgG (ELISA) was requested, showing a positive result with a value of 2.27 (normal values < 1.01). Laboratory tests showed eosinophils 0.29 x 10e9/L, leukocytes 10.47 x 10e9/L CRP 35.99 mg/L, D-dimer 1,410 ng/mL and ferritin 663.3 ug/L. Seven days of treatment with dexamethasone was completed until oxygen therapy was withdrawn and treatment with ivermectin 200 mcg/kg/day for two days was initiated with complete resolution of the skin condition.

A 74-year-old woman from Honduras, resident in Spain for seven years, with a history of pyrazolone allergy, hypertension, dyslipidaemia, chronic kidney disease and disseminated tuberculosis correctly treated for four years, admitted for bilateral SARS-CoV-2 pneumonia requiring dexamethasone 6 mg/day. On the tenth day of treatment, the patient presented intense pruritus mainly on the upper limbs. Physical examination revealed an erythematous, serpiginous, raised linear lesion in the right peri-umbilical abdominal area (Fig. 1). Laboratory tests showed eosinophils 0.0 x 10e9/L, lymphocytes 1.20 x 10e9/L, CRP 19.17 mg/L, D-dimer 650 ng/mL, and ferritin 320 x 10e9/L. Serology for S. stercoralis IgG (ELISA) was positive with a value of 2.47 (normal values < 1.01), so treatment was started with ivermectin 200 mcg/kg/day for two days with complete resolution of the skin condition. In both cases, further studies with serology for HIV-1/2, viral hepatitis and HTLV-1/2 were negative. At three months, both patients were still asymptomatic and the follow-up serology for S. stercoralis IgG remained positive pending subsequent controls.

Fig. 1.

Serpiginous and erythematous linear rash (larva currens) in the abdominal region. The black arrows indicate the path of the rash.

Other described cases of reactivation of S. stercoralis in patients with SARS-CoV-2 pneumonia include immunosuppressive therapy with tocilizumab or anakinra and corticosteroid therapy.^2–4 In our experience, both patients had reactivation of S. stercoralis while receiving low-dose dexamethasone treatment (6 mg/day). The prevailing clinical presentation was the cutaneous manifestation in the form of larva currens, a transient linear serpiginous rash representing filariform migration of S. stercoralis larvae under the skin. The absence of eosinophilia is noteworthy, and may be absent due to treatment with dexamethasone, possibly responsible for the reduction in peripheral eosinophil count. The clinical course was favourable with resolution of the symptoms after completing two doses of ivermectin 200 mcg/kg/day. Monitoring of treatment response was based on clinical response, as the period of serological response can extend up to two years.

Reactivation of chronic S. stercoralis infection in patients on dexamethasone treatment for SARS-CoV-2 pneumonia warrants a high index of clinical suspicion in immigrant populations from endemic areas,⁵ and new onset rash or pruritus should be monitored as a possible early indicator. Diagnostic confirmation by serology is not available in all centres and the time elapsed until results are obtained can vary from five to 10 days, which implies a significant delay in the established diagnosis.

When faced with a patient hospitalised for moderate-severe COVID-19 infection on treatment with dexamethasone and with risk factors for S. stercoralis infection, we suggest considering the possibility of empirical treatment with ivermectin, given the potential life-threatening complications of this infection. Likewise, to improve the diagnosis and management of these patients, it would be necessary to speed up the serology results for S. stercoralis IgG, ensure access to treatment with ivermectin as an essential medication and standardise protocols for action, especially in centres with a high prevalence of patients from endemic areas at high risk of chronic-latent S. stercoralis infection.