Novel Relapsing Fever Spirochete in Bat Tick

Tick-borne relapsing fever in western North America is a zoonosis caused by spirochetes in the genus Borrelia that are transmitted by argasid ticks of the genus Ornithodoros (1). Human disease occurs in many focal areas and is associated with infections of Borrelia hermsii, B. turicatae, and possibly B. parkeri (2,3). Although the ecologic parameters that maintain B. hermsii and B. turicatae differ, human infections usually occur in rustic cabins (B. hermsii) and caves (B. turicatae) inhabited by ticks and their terrestrial vertebrate hosts (1). Recently, Gill et al. (4) provided evidence that the argasid bat tick, Carios kelleyi, feeds upon humans. Subsequently, Loftis et al. (5) used PCR analysis and DNA sequencing to detect in C. kelleyi an unidentifi ed Borrelia species that was closely related to B. turicatae and B. parkeri.

EC30-39 Swine Sanitation

From the very beginning of Nebraska's agricultural development its farmers have recognized that the production of swine must of necessity accompany the growing of corn. The latter, one of the state's most important staples, cannot be marketed in a more economical manner than after having been transformed into pork, bacon, and lard. As a result the state has for many years maintained a rather dense swine population mainly divided into large herds kept on relatively small areas of land. This density of population, as well as certain practices in management and selective breeding, has brought about conditions favorable for the propagation of a number of microbic or parasitic diseases which, in a costly manner, force themselves to our attention. The various factors which affect the incidence of swine diseases are numerous and in a given situtation may be so intricately interwoven as to baffle the observer. This extension circular discusses these factors and how to prevent the spread throughout the swine population.

COMMENSAL RODENTS

The evolution of effective rodent control has been greater in the past 20 years than during the previous 200 years. Mankind need no longer fear the "black death," typhus, and other rodent-borne diseases. Likewise, there is no longer any reason why we must bear the cost of serious economic losses because of commensal rodent damage to property. Unfortunately, the latter still totals many millions of dollars each year. Damage and contamination of food products by house mice now probably equals or exceeds that caused by rats.

Emergence of Diseases From Wildlife Reservoirs

Interest in the epidemiology of emerging diseases of humans and livestock as they relate to wildlife has increased greatly over the past several decades. Many factors, most anthropogenic, have facilitated the emergence of diseases from wildlife. Some livestock diseases have ‘‘spilled over’’ to wildlife and then ‘‘spilled back’’ to livestock. When a population is exposed to an infectious agent, depending on an interaction of factors involving the host, agent, and environment, the population may be resistant to infection or may become a dead-end host, a spillover host, or a maintenance host. Each exposure is unique; the same species of host and agent may respond differently in different situations. Management actions that affect the environment and behavior of a potential host animal may allow the emergence of a new or as yet undetected disease. There are many barriers in preventing, detecting, monitoring and managing wildlife diseases. These may include political and legal hurdles, lack of knowledge about many diseases of wildlife, the absence of basic data on wildlife populations, difficulties with surveillance, and logistical constraints. Increasing interaction between wildlife and humans or domestic animals may lead to disease emergence and require innovative methods and strategies for disease surveillance and management in wildlife.

A Preliminary Linkage Map of the Hard Tick, Ixodes Scapularis

Blackwell Publishing Ltd. A linkage map of the Ixodes scapularis genome was constructed, based upon segregation amongst 127 loci. These included 84 random amplified polymorphic DNA (RAPD) markers, 32 Sequence-Tagged RAPD (STAR) markers, 5 cDNAs, and 5 microsatellites in 232 F1 intercross progeny from a single, field-collected P1 female. A preliminary linkage map of 616 cM was generated across 14 linkage groups with one marker every 10.8 cM. Assuming a genome size of ~ 10 9 bp, the relationship of physical to genetic distance was found to be ~ 300 kb/cM in the I. scapularis genome.

A preliminary linkage map of the tick, Ixodes scapularis

A linkage map of the Ixodes scapularis genome was constructed based upon segregation amongst 127 loci. These included 84 random amplified polymorphic DNA (RAPD) markers, 32 Sequence-Tagged RAPD (STAR) markers, 5 cDNAs, and 5 microsatellites in 232 F1 intercross progeny from a single, field-collected P1 female. A preliminary linkage map of 616 cM was generated across 14 linkage groups with one marker every 10.8 cM. Assuming a genome size of ∼109 bp, the relationship of physical to genetic distance is ∼300 kb/cM in the I. scapularis genome.

Borrelia lonestari Infection after a Bite by an Amblyomma americanum Tick

Erythematous rashes that are suggestive of early Lyme disease have been associated with the bite of Amblyomma americanum ticks, particularly in the southern United States. However, Borrelia burgdorferi, the causative agent of Lyme disease, has not been cultured from skin biopsy specimens from these patients, and diagnostic serum antibodies usually have not been found. Borrelia lonestari sp nov, an uncultured spirochete, has been detected in A. americanum ticks by DNA amplification techniques, but its role in human illness is unknown. We observed erythema migrans in a patient with an attached A. americanum tick. DNA amplification of the flagellin gene flaB produced B. lonestari sequences from the skin of the patient that were identical to those found in the attached tick. B. lonestari is a probable cause of erythema migrans in humans.

Zoonotic Diseases in the Changing Arctic

Compatible with the biotic uniformity of northern regions, the occurrence of certain organisms which cause zoonotic diseases is general throughout the Arctic. In the past, most frequently affected by such diseases have been aboriginal peoples whose way of life involved encroachment upon naturally occurring parasite-host assemblages. Now, as changes take place in socioeconomic conditions in the Arctic, the importance of zoonotic diseases as a cause of morbidity may lessen among such peoples, but on the other hand, more nonaborigines may be affected. Although my remarks relate mainly to Alaska, again the biotic uniformity of the North seems to have its effect even with regard to man's activity, for similar changes are occurring throughout the arctic zone. Thus far, the natural environment has not been extensively disrupted at higher latitudes, and the arctic regions remain important for basic research in the natural history of zoonotic diseases. Because of the biotic peculiarities of these regions, conditions there especially favor the investigation of parasite-host relationships and the transmission of disease among the inhabitants. Significant benefit to the human population, in the temperate zone as well, can be expected to accrue from future studies in an undisturbed arctic wilderness.

Parasites and Diseases of Mullets (Mugilidae)

The following treatment of parasites, diseases and conditions affecting mullet hopefully serves several functions. It acquaints someone involved in rearing mullets with problems he can face and topics he should investigate. We cannot go into extensive illustrative detail on every species or group, but do provide a listing of most parasites reported or known from mullet and some pertinent general information on them. Because of these enumerations, the paper should also act as a review for anyone interested in mullet parasites or the use of such parasites as indicators about a mullet's diet and migratory behavior. Unfortunately, limited space prohibits us from presenting all the references used. The paper also deals with the public health aspects of eating or selling mullet, whether the product is to be raw, cooked, salted or smoked.

Emerging Marine Diseases: Climate Links and Anthropogenic Factors

Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997-98 is coincident with high El Niño temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations.

SIGNIFICANCE AND CONTROL OF FUNGAL DISEASES RELATED TO BIRD ROOSTS

Certain fungi have been found frequently as saprophytes in areas containing large amounts of bird excreta. These fungi have the ability to survive, multiply, and cause disease once they have entered a host. Two of these are Crypto-coccus neoformans and Histoplasma capsulatum. Both may easily become airborne and be disseminated throughout an area by the prevailing winds. C. neo-formans is commonly isolated from the excreta of pigeon habitats, and in turn has been associated with clinical cases of cryptococcosis, while blackbird roosts, harboring H. capsulatum, have been responsible for several outbreaks of histoplasmosis. When either of these fungi have become established in nature, the sites may become foci for infection and epidemics may occur if the sites are disturbed. This has led to investigation of these organisms with respect to: 1) the frequency of isolation of H. capsulatum from the soil beneath blackbird roosts in a histoplasmosis endemic area; 2) the infectivity of undisturbed roosts positive for H. capsulatum; and 3) the effectiveness of chemical decontamination of areas containing C. neoformans or H. capsulatum.