An extensive review of the importance of ectoparasite control on mammals and its relation to public health. Fleas, ticks, mites, and lice are discussed in detail, as well as their roles as vectors of disease of public health importance in the U.S. Ectoparasite control methods are described. The role of flea control and/or rodent control in the prevention or control of enzootic plague is discussed. Specific recommendations on use of insecticides within bait boxes are provided, as is the practice of burrow dusting for flea control. Control of lice that infect humans is discussed, as well as the potential role of lice in epidemic typhus in some areas of the world. Mites that affect humans, including chiggers and the tropical rat mite, are mentioned and control recommendations are provided. The role of ticks in serving as vectors of various rickettsia, bacteria, viruses, and protozoa is discussed in some detail, especially in relationship to human diseases that tick bites may cause. Tick biology, identification, and control are described in detail and some case studies are provided. A list of literature citations regarding ectoparasites is included.

An increasing trend in the frequency of human bubonic plague cases in the United States, the principal sources of human Infection, and emerging control techniques are described. Development of an integrated control program involving public health education, citizen participation in plague surveillance, and insecticidal control of flea vectors in response to evidence of plague and potential human exposure substantially reduced human plague cases in a Bernalillo County, New Mexico, hyperendemic plague area. Permethrin 0.5% dust (Pyraperm 455) applied at a rate of 7 g per burrow was found to provide effective control of flea vectors for at least 6 weeks.

Rodent populations - particularly those that live in close proximity to man - constitute a perennial and often severe threat to man's health as reservoirs and often as direct sources of infection for a wide variety of viral, rickettsial, and bacterial disease producing agents. The following will discuss the place of rodent population reduction for the control of plague, a bacterial disease of rodents transmitted by fleas endemic in the western United States.

Vector-borne disease prevention and control strategies, aside from those associated with domestic rodents, have rarely involved management of vertebrate populations, even though in many cases such management would appear to represent the most effective and economical long-term approach. Prevention of a long list of arthropod transmitted diseases ls often at best a stop-gap procedure undertaken only after substantial disease hazard is detected in reservoir populations. More often, control actions await the detection of human cases, at which time short-term emergency control measures may be conducted, usually involving the use of toxicants against arthropod vectors and occasionally vertebrate reservoirs. In some cases, action is not taken because techniques are not available, but more often the decisive factors in action versus inaction are economic, jurisdictional, and/or organizational. Often, public health problems proceeding from unmanaged vertebrate populations are (justifiably) given low priority on the basis of costs versus benefits. If the same populations constitute a problem for health, economic, wildlife, or recreational interests, it may behoove us to pool our priorities, skills, and resources in collaborative management program designed for the greatest overall benefit rather than to proceed only on those programs that can be justified on the basis of one special Interest.

During the first quarter of the 20th century, massive rat-borne plague epidemics occurred in port cities of the United States in conjunction with the last world-wide pandemic which originated in China in 1893. By 1950, plague was found to be firmly established in wild rodent populations in states west of the 100th meridian. Presumably because of improved sanitation coupled with retreat of the world-wide pandemic, there have been no human cases in this country associated with urban rats since 1924. However, sporadic cases, fewer than 10 per year, are reported as due to contact with wild rodents, lagomorphs, rural rats, and/or their fleas. Recent observations suggest that: a) in the current decade there has been an increase in human plague cases; b) there continues to be a serious potential of a single undiagnosed and untreated case, which possibility is intensified by the very paucity of human cases decreasing the likelihood of a correct diagnosis and by changing patterns of life exhibited by members of our society (e.g., hippie communes and a generally increased mobility); and c) the apparent distribution of plague only in the area west of the 100th meridian might be found to represent an unrealistic generalization if adequate surveillance were carried out. At the present time human plague cases from wild animal sources tend to be isolated events both spatially and temporally and often cannot be attributed to confined and definable epizootic sources amenable to effective control programs. Improved means for epizootic control and long-term management of enzootic plague sources must be sought aggressively. These measures should include development of: a) a surveillance network to detect plague activity in rodent and lagomorph populations throughout the western United States; b) effective, yet ecologically sound, means of ectoparasite control, including suitable materials and methods of application; c) methods for management of plague-susceptible wild animal populations, particularly where they exist in contact with high use recreation and residential areas; and d) more extensive knowledge of enzootic plague and the factors that bring about epizootic plague and potential human contact.

Plague is widespread among rodents and their fleas in the western United States, but most human cases occur in several definable, ecologically unique, and geographically limited high risk areas in the Southwest and Pacific Coast states. Control strategies to prevent human cases in high risk areas must vary from one epizootic focus to another, depending on such basic ecological factors as rodent/flea species involved; their distribution, abundance, seasonality, and relationship with the plague organism; climatic factors that affect transmission; the lifestyles of human residents; and others. This paper briefly summarizes preliminary results of a long-term program to define human risk and develop effective surveillance and control measures against plague in a north-central New Mexico plague focus.

Carnivores obtain plague infection through ingestion of infected rodents or rabbits or via flea bite. Most are resistant to infection, show little or no symptoms, and produce antibodies to Yersinia pestis which may persist for several months. Consequently, carnivores can be used as serological plague sentinels using the specific passive or indirect hemagglutination test in the laboratory. A carnivore serology program for plague detection began in California in 1974. The program is a cooperative effort incorporating state and federal vector-borne disease units and state and federal predator animal control personnel. The program has proven to be an important tool in the overall statewide plague surveillance program of the California Department of Health Services, and has been effective in detecting plague over broad geographical areas of the state, as well as in areas heretofore unknown to experience plague activity. Carnivore serology has also proven useful in helping to delineate the extent of plague epizootics, and has given insight into the patterns of enzootic plague among wild rodent populations.