Chloropidae are not of importance in human medicine in the same way as blood sucking parasites such as mosquitoes or Simuliidae. Also, in contrast to specialist pathogens such as "Plasmodium" or "Trypanosoma", the pathogens that Chloropidae transmit are not adapted to particular vectors. However, some Chloropidae are troublesome in that they act as purely mechanical agents of disease transmission. Species that occur in large numbers and are attracted to animal secretions such as tears and dung, sometimes cause serious irritation and infection. Prominent examples include the eye gnat genera: "Liohippelates" in the Americas and "Siphunculina" in parts of Asia. Their larvae are soil saprophages that have several generations per year and accordingly can multiply rapidly. In warm seasons they may emerge in huge numbers and swarm about the eyes, up the nostrils and in the mouths of mammals, including livestock and humans. The irritation can be so great as to compel the use of gauze face masks for humans and even for animals. Furthermore, the flies are so small that the gauze must be very fine to offer effective protection. Apart from the irritation however, the flies frequently move from host to host and from anus to face or to open lesions; accordingly they can be dangerous vehicles for many infectious organisms. Bacterial examples, in particular in the Caribbean and parts of South America, include the transmission of "Treponema pallidum pertenue", the spirochaete that causes yaws. Less specifically, any of a range of bacterial species can cause human acute conjunctivitis (pinkeye), and understandably the incidence of pinkeye tends to rise sharply when relevant species of Chloropidae are swarming. "Haemophilus influenzae" biotype "aegyptius" is the pathogen that causes the highly dangerous Brazilian purpuric fever; in children it usually is rapidly fatal, and various species in the family Chloropidae are potential transmitters of the disease. As another example of bacterial transport, some species of Chloropidae may carry various strains of Streptococcal skin infections. Apart from bacterial pathogens, Chloropidae also may transmit viral diseases; in particular they have been shown to carry the vesicular stomatitis virus. Though Chloropidae generally do not attack vertebrates directly, the larvae of the Australian frog flies, genus "Batrachomyia", are exceptions. They cause myiasis in frogs.