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The epizootic of rabies in raccoons in Maryland has been accompanied by 129 confirmed cases of rabies in cats from Jan 1, 1983 to Sept 30, 1992 and only 12 cases in dogs. An epidemiologic and clinical study of rabies in cats was conducted for the period Jan 1, 1983 to May 31, 1986. Only 3 of 31 rabid cats had a history of being currently vaccinated against rabies, and 13 were of unknown ownership. A history of prior wound or injury within 6 months of onset of signs of rabies was reported in 11 of the cats and most of these had a wound in a hind limb. The median interval between reporting of a wound and a development of rabies was 4 to 6 weeks. Rabies in cats is difficult to diagnose in the early stages and, of the 14 cats examined by a veterinarian, only 3 were believed to have rabies on initial examination. Major signs of rabies in cats reported by veterinarians included behavior change, gait abnormality, strange or unusual look in the eyes, and a wound within the preceding 6 months. Owners reported increased frequency of vocalization as an early sign. Postexposure treatment was given to 194 human beings including 63 veterinarians or their personnel. The estimated cost of postexposure biologics was +68,000.

The epizootic of rabies in raccoons entered Maryland in 1981 and systematically moved through the state affecting raccoons in all counties except those of the lower Eastern Shore. A precoded surveillance form was provided to all county and city health departments and data were requested for each animal head submitted for testing for the year 1985. The disease persisted and, in 1987, all counties previously reporting rabies in raccoons also had documented cases in other species. The incidence of rabies in raccoons increased in late winter and peaked in March. Most human exposures occurred during daylight hours and in private yards. Agricultural areas were similarly affected by rabid animals. Analysis of vaccination status of animals exposed to rabid animals gave estimations of statewide vaccination rates for dogs (70%) and cats (28%). The danger of rabies in cats was emphasized by the large number of animals exposed by each rabid cat. The spillover of rabies in raccoons to other species persisted in all jurisdiction through 1992, with periodic upsurges of disease at 3- to 4-year intervals as the raccoon population is replenished. Rabies was not diagnosed in any human beings.

Records from the Maryland Public Health Department were screened for confirmed rodent and lagomorph rabies between 1981 and 1986. Questionnaires were designed for collection of information about events that led to the exposure of human and/or domestic animals to rabid rodent or lagomorphs. These species comprised 1.2% of all the reported rabies in the state. Woodchucks (Marmota monax) constituted 80.0% of all the reported rodent/lagomorph rabies cases in Maryland. The majority showed aggressive behavior (55.0%). Woodchucks exposed 15 persons (75.0% of all the exposures by rodents/lagomorphs). Domestic animal and human rabies exposure due to rodents and lagomorphs represents a small but significant number of the total exposure to rabid animals.

Recent analysis of the Faroe Islands MS outbreak suggests that initiation of MS could occur at any time of life (before menopause), with puberty acting as an inducer for those with early onset of disease. It was further suggested that disease induction relates to hormonoimmunologic factors. This paper critiques current epidemiologic knowledge of MS and suggest where the Faroe Islands analysis leads. The generally accepted unimodality of the age-incidence curve is challenged with several examples of bimodality, and the concept of the hormonoimmunologic nature of MS induction is strengthened by analogies with tuberculosis, postvaccinal rabies encephalitis, and systemic lupus erythematosus (SLE). Major hormonal, lipid, and neurologic changes occur during the puberty period, but their roles in MS induction are undetermined. The concept of bimodality suggests that the search for etiologic risk factor relationships using small age at onset groups is more appropriate than using total MS populations. The question of the representativeness of the Faroe Islands outbreak can only be resolved by studies in other populations.

The transient, sublethal infection produced by intracerebral inoculation of the Flury high egg passage (HEP) strain of rabies virus into adult mice was converted into a lethal one (approx. 80 to 100% mortality) by administering 150 mg/kg cyclophosphamide (CY) 2 days after infection. Immunosuppressed, infected animals showed no immunological response to rabies and died 15 to 20 days after infection. However, mortality was reduced to 12% when suppressed mice were adoptively immunized, 4 days after infection, with an intravenous injection of 60 X 10(6) spleen cells from rabies-immune syngeneic donors. The lymphocytes obtained early after donor immunization (4 to 11 days) reduced mortality, whereas those obtained late (16 to 32 days after immunization) were not effective. The ability of donor cells to protect animals corresponded very closely with donor cytotoxic T lymphocyte (CTL) activity. Within 4 days after immune cell transfer, serum neutralizing antibody and CTL levels in recipients were comparable to those found in virus-infected control animals. Immune donor cells were fractionated into thymus-derived (T-enriched) and bone marrow-derived (B-enriched) subsets. The T and B subsets reduced mortality to 32% and 34% respectively. CTL and serum neutralizing antibody responses could be detected in these animals, although they appeared later than in mice treated with unfractionated immune spleen cells. The present study demonstrates that both B and T lymphocytes are required for optimum clearance of rabies from the central nervous system (CNS) and suggests a functional role for rabies-specific CTL in vivo.

A study was conducted among 13,844 members of a meat-cutter's union, from July 1949 to December 1980, to examine cancer occurrence in the meat industry. Separate analyses were carried out for the whole group, and for subgroups defined by job-categories characteristic of the industry, including a control group. Mortality was compared with that of the United States through the estimation of standardized mortality ratios (SMR) and proportional mortality ratios. A statistically significant proportional mortality ratio of 2.9 was obtained for Hodgkin's disease among abattoir workers; the SMR of 2.2 was not significant. Among meat-packing plant workers, highly statistically significant SMRs were recorded for bone cancer, SMR = 9.6; cancer of the buccal cavity and pharynx, SMR = 3.4; and lung cancer, SMR = 1.9. The role of oncogenic viruses and other carcinogenic exposures was investigated.

Establishing a causative relationship for the association between geographic distribution of caves and the occurrence of rabies in foxes in the United States will require the demonstration of a plausible biological mechanism and proof from carefully designed epidemiologic studies. Considerable data implying biological plausibility exists in the form of rabies as an enzootic disease in bats, bat predation by ground animals, bat migratory patterns, and several possible virus transmission routes to the fox. Further data showing development of rabies in the fox following appropriate bat contact are needed. Evidence leading to the acceptability of a causal relationship should distinguish between spurious, causal, and indirect hypotheses. An alternative hypothesis is whether cave areas are superior fox habitats and harbor far greater populations of foxes than do noncave areas.

The concept that the pathogenesis of multiple sclerosis (MS) is dependent on both an environmental factor and host factors associated with the puberty period was tested using the data for the Faroe Islands "outbreak." Although this "outbreak" affected only 25 individuals, its value may be unique since it is the only virgin outbreak described. The population affected demonstrated an age-associated bimodality. Incubation period for the older group, using 1942 (midpoint of British troop occupation) as onset time, was 5 years, while for the younger group, using puberty as onset time, a similar 5.7-year incubation period was demonstrated. Male and female incubation periods for both groups were similar, demonstrating an internal validity check. Although 10 cases were below the age of puberty at the time of the occupation, none of these developed disease prior to reaching puberty. The data suggest that onset of pathogensis of MS is dependent on passing or having passed through the puberty period. This would explain why MS is rarely seen below age 10, is unusual below age 15, why age 15 has been a "critical time" in migration studies and why females have an earlier onset than males. The data further indicate that susceptibility to MS may be acquired over a wide range of ages. The fact that many aging curves such as those for estrogen, testosterone or 17-hydroxycorticosteroid show striking similarity to the MS incidence curves raises the question whether infection is the entire explanation for the age distribution.

A follow up study of 7261 white women from a meatcutters' union was conducted between July 1949 and December 1980. Proportional mortality ratio (PMR) and standardised mortality ratio (SMR) analyses, using the United States general population mortality rates, were conducted for the group as a whole and for subgroups defined according to the four main job categories in the meat industry, and a fifth category of workers from outside the industry but belonging to the same union (control group). At least a threefold risk of death was observed both for myeloid leukaemia and non-Hodgkin's lymphomas among workers in the meat department of retail food stores. No excess risk from these diseases was observed in the control group. SMRs of 4.56, 4.02, and 1.95, which were statistically significant, were observed for lung cancer among workers in chicken slaughtering plants, meatpacking plants, and retail food stores respectively. The lung cancer SMR for abattoir workers was 1.41 (not significant) and 1.11 for workers in non-meat companies. The role of potentially harmful exposures within the industry in the occurrence of these excesses is discussed.