The first reported case of Blaptica dubia cockroach allergy

Periplaneta americana and Blattella germanica cockroaches are widespread, and risk of sensitization increases in urban environments where these roaches thrive as household pests. There are no prior reports of Blaptica dubia cockroach allergy, though human exposure to B. dubia is increasing through commercial breeding as feeder insects.

A 50-year-old B. dubia cockroach breeder presented with progressively worsening upper and lower respiratory symptoms in recent years. Symptoms were worse with exposure to her B. dubia roach colony. Skin prick testing (SPT) to B. dubia cast skin, internal organs, and feces was performed in both the subject and a human control. Testing for P. americana and B. germanica sensitization was also performed in the subject. SDS-Polyacrylamide gel electrophoresis (PAGE), immunoblots, and enzyme-linked immunosorbent assays (ELISA) studies were performed using the subject and control serums to explore for specific IgE binding to B. dubia as well as P. americana. Our results showed SPT was positive to B. dubia internal organs in the subject and negative in the control. In the subject, SPT was negative to P. americana though intradermal (ID) testing was positive and serum specific IgE (sIgE) testing was negative to B. germanica. Immunoblotting of the subject's serum to B. dubia internal organ extract showed several distinct bands of IgE binding at 47 kilodaltons (kD), 68 kD, 74 kD, 83 kD, and 118 kD. The strongest band was at 118 kD on B. dubia immunoblotting, which was absent in P. americana on SDS-PAGE. ELISA studies showed an increased IgE response to both B. dubia and P. americana in the subject versus the control.

This case confirmed the first reported allergy to B. dubia cockroaches. There may be cross-reactivity between B. dubia and P. americana, though our case suggests SPT and sIgE testing using P. americana and B. germanica extract has potential to miss a B. dubia cockroach allergy. This allergy is likely underreported, and further study is needed to explore the natural history of B. dubia cockroach allergy.