Ultrastructure of Cimex lectularius salivary glands after blood meal infected with Bartonella henselae

Bed bugs (Hemiptera:Cimicidae) are hematophagous ectoparasites of humans and animals. Two species, Cimex lectularius and C. hempiterus, are known to bite humans and occur in temperate and tropical climates. Over the last 30 years, reports of both species have been increasing in hostels, hotels, and permanent residencies. Bed bugs have been implicated in the transmission of up to 40 disease agents, including various Bartonella species, however biological disease transmission has not yet been confirmed. Bartonella spp. are transmitted by a variety of arthropods, including fleas, lice and sand flies, and it is speculated that bed bugs may also serve as a potential vector. In this study, we used an artificial membrane to feed two treatment groups of adult Cimex lectularius rabbit blood that was either infected or uninfected with Bartonella henselae (8.8 x 10⁸ CFU/mL). After two weeks, the presence of Bartonella henselae was assessed via PCR, and salivary glands from infected and uninfected bed bugs were dissected and fixed in 2.5% glutaraldehyde and 2mM sodium cacodylate buffer. Transmission electron microscopy (TEM) was performed on salivary glands using a JEOL 1230 120kV electron microscope to determine the presence of Bartonella henselae within the salivary gland. Even though bed bugs fed on B. henselae infected blood two weeks earlier were PCR positive for the agent, there were no bacteria seen upon TEM consistent with B. henselae. Further studies should be conducted to confirm these (negative) findings and to rule out the possibility of mechanical transmission of the agent.