Key Words  
  Lice, bed bugs, fleas, vectors
  The role of biting or bloodsucking pesu such a lice, bedbug and flea in the'transmission of human pathogens is well known. The role of other anhropod pesu such as cockroaches, ants and flies is less clear and whilst there is a large body of evidence that they carry a wide range of pathogenic organisms, whether they act as reservoirs or vectors of these organisms is largely unknown. The fint pan of tlus paper deals with the biting, bloodruchng and burrowing pests that directly attack humans and gives details of the types of disease that they can transmit. The= include not only diseases that are well known to be transmitted by this means (such as typhus) but also recent evidence about the role of some of thew pests as possible transmitters of Hepatitis B virus, and a brief discussion of whether or not they can act u vmors of HIV. The main pa^ of the paper is devoted to a detailed review of the groups of organisms that are known to be carried by the other types of urban insect pesu. These indudc viruses, bacteria, chlamydia, protozoq fungi and helminths. Simply finding an organism in or on an imm pen is not sufficient evidence that the pest is acting as a vmor. The find pan of the paper is devoted to a ducusion of the evidence u to whether these pests actually transmit human pathogens.