Public Health and Medical Entomology
Other species of fleas that are parasites of rodents are involved in the transmission of plague and murine typhus, both of which occur in the southwestern U.S. You are encouraged to learn more about the biology of fleas, especially the cat flea, so that you can make more informed decisions about health risks to you and your pets, how to avoid being bitten, how to prevent or suppress infestations, and whether flea control is warranted in and around your residence. Bites of cat fleas can be very annoying to humans because chemicals in flea saliva stimulate an immune response that causes itching. A flea of potential importance to vacationers in subtropical and tropical areas is the so-called “Chigoe flea,” Tunga penetrans. At least 30 species of fleas have been found on mammals in Indiana, but only the cat flea is a serious pest of pets, livestock, and humans. Despite its common name, the cat flea is the primary flea that infests dogs. Like all fleas, the cat flea develops from egg to adult via a process of “Complete metamorphosis.” This process involves the transformation of the last larval stage into a non-feeding pupal stage. The presence of flea bites on a person suggests that the home is supporting the development of flea larvae, which can be a continuous source of adult fleas that then infest your pets. Infested barns can be a continual source of adult cat fleas that can infest cats and dogs that sleep in them, and a source of flea bites to people who enter them. Pet owners contribute to the success of cat fleas by failing to monitor their pets for the presence of adult fleas and by failing to practice sanitation methods that reduce the development of flea larvae. Effective control of cat fleas can be difficult and complicated, and depends on the conditions in and around homes, yards, and barns that affect the number of flea larvae that develop. We recommend consulting with a veterinarian regarding which product and approach to use for control of fleas on pets and consulting with a professional pest control company regarding which product and approach to use for control of flea infestations in homes, yards, and barns. Controlled scientific studies have shown that ultrasonic devices have no effect on fleas and that products such as brewer’s yeast, B-complex vitamins, and garlic are not effective flea repellents. Several Web sites provide information on the biology and control of fleas, nearly all of which focus on the cat flea. The following Web site is recommended for accurate and detailed information on fleas of public health risk, including information on plague and murine typhus, and the chigoe flea, Tunga penetrans. A recent textbook by G. Mullen and L. Durden, Medical and Veterinary Entomology, has an excellent chapter devoted to fleas and flea-borne diseases that cover biology, behavior, medical and veterinary risk, and general information on prevention and control.
One can look at the history of pigs in research as a barometer of attitudinal changes toward animals, both by the public and the professions that make use of them. “We want to know: How important is social contact and space? What do they like and need.” Over the last fifteen years, there has been an increase in the amount of research done on pigs for welfare determinations for pigs in agriculture production. Temple Grandin has posted a series of her research articles on pigs relating to handling and environment when they are being raised as a food resource. For general information on husbandry see Comfortable Quarters for Pigs in Research Institutions by Temple Grandin. Pigs were one of the earliest research animals: in ancient Greece Erasistratus used them to investigate the mechanics of breathing. As scientific research became a large and successful endeavor, pigs, like rats, became increasingly popular since most people lack the emotional attachment to swinethey became in many protocols the replacement animal for dogs and cats. Miniature pigs are purpose bred for research; they are smaller than those bred for production, with a much slower growth curve, but physiologically in all other ways they are similar to agricultural pigs. During recent years, pigs have become utilized for their biological parts, e.g. cardiac valve replacement; the area of xenotransplantation, a recent development, has resulted not only in increased scientific research but also new and difficult ethical questions. Given the exponential increase in biotechnological research using pigs, along with genomic knowledge in general, there are ethical concerns now that could never have been foreseen. There is a wealth of information about pigs since they have become a critically important animal in biomedical research: Information Resources on Swine in Biomedical Research 1990-2000 contains resources as well as informative articles as to their biology. Although bacterial illnesses accounts for most symptomatic disease in research pigs, an asymptomatic virus load can interfere with research in less obvious but critical ways. Comfortable Quarters for Pigs in Research Institutions, has specific details. Genetically altered pigs for potential use in clinical xenotransplantation are now technically feasible as precise genetic modifications in the pig genome are achieved. The housing standards for pigs raised in agriculture for food are very different from those for pigs used in research institutions. Why do you think the standards are so different? For example, the practice of giving straw to pigs for bedding and enrichment, cited in the Comfortable Quarters for Pigs in Research Institutions is generally not standard in research institutions and rare in agriculture, although the Guide noted above states, “When supplemental zone-heating is not provided, farrowing houses should be bedded with a suitable material such as straw.