Dr. Naides reply

We thank Dr. Russell for raising the issue of reporting the false positivity rate of antinuclear antibody (ANA) indirect immunofluorescent assay (IFA) testing.1 It is difficult, however, for a laboratory to state a false positive rate, per se, as the determination of “falseness” is dependent on clinical evaluation that is typically not available to most laboratories.

Evaluating the serological status of COVID-19 patients using an indirect immunofluorescent assay, France

ABSTRACTAn indirect immunofluorescent assay was developed in order to assess the serological status of 888 RT-PCR-confirmed COVID-19 patients (1,302 serum samples) and controls in Marseille, France. Incorporating an inactivated clinical SARS CoV-2 isolate as the antigen, the specificity of the assay was measured as 100% for IgA titre ≥ 1:200; 98.6% for IgM titre ≥ 1:200; and 96.3% for IgG titre ≥ 1:100 after testing a series of negative controls as well as 150 serums collected from patients with non-SARS-CoV-2 Coronavirus infection, non-Coronavirus pneumonia and infections known to elicit false-positive serology. Seroprevalence was then measured at 3% before a five-day evolution up to 47% after more than 15 days of evolution. We observed that the seroprevalence as well as the titre of specific antibodies were both significantly higher in patients with a poor clinical outcome than in patients with a favourable evolution. These data, which have to be integrated into the ongoing understanding of the immunological phase of the infection, suggest that serotherapy may not be a therapeutic option in patients with severe COVID-19 infection. The IFA assay reported here is useful for monitoring SARS-CoV-2 exposure at the individual and population levels.

Serological Survey of Ehrlichia canis and Anaplasma phagocytophilum in Dogs from Central Italy: An Update (2013–2017)

Ehrlichia canis and Anaplasma phagocytophilum are tick-borne bacteria of veterinary concern. Indirect immunofluorescent assay was carried out to detect antibodies against E. canis and A. phagocytophilum in 1026 owned dogs living in Central Italy during the period 2013–2017. One hundred and eighty-six (18.12%) dogs were positive for at least one pathogen and 14 (1.36%) for both agents. More in detail, 166 (16.18%) samples were positive for E. canis and 34 (3.31%) for A. phagocytophilum. No statistically significant differences in the seroprevalence values related to gender were detected, whereas the highest rate to E. canis occurred in animals aged more than 10 years. Mean seroprevalence values for both E. canis and A. phagocytophilum detected in 2014 and 2015 were statistically higher with respect to other years. Even though dogs’ owners are informed about the risk of pet infections by tick-borne pathogens and prophylaxis against ticks is often executed, E. canis and A. phagocytophilum are still present and infect the canine population in Central Italy.

Unusual Maculopapular Rash on the Scalp of a Patient with Mediterranean Spotted Fever

Objective: To report a rare case of maculopapular rash on the scalp in a patient with Mediterranean spotted fever (MSF). Clinical Presentation and Intervention: A 58-year-old woman with breast cancer and chemotherapy-induced alopecia contracted MSF. Her clinical features were typical, except for a maculopapular rash covering the scalp. The diagnosis of MSF was confirmed by immunofluorescent assay. The disease had a favorable course and the patient was discharged in good condition. Conclusion: The rash on the scalp described in this report enriches our knowledge on the clinical characteristics of MSF.