Excess of seminomas observed in Vietnam service U.S. military working dogs.

During the Vietnam War, US military working dogs served with their companion dog handlers in close proximity, sharing common exposures to war-related activity, many zoonotic infectious agents, chemical pesticides, phenoxy herbicides, and extensive use of therapeutic drugs. To gain insight into the effects of the Vietnam experience, we investigated the occurrence of neoplasms in military working dogs based on standard necropsy examination by the Armed Forces Institute of Pathology. We observed that these dogs experienced significant elevated risks for testicular seminoma and, independently, testicular dysfunction. Experimental evidence shows testicular dysfunction and impaired spermatogenesis in laboratory animals exposed to phenoxy herbicides, dioxin, or tetracycline, and antibiotic used extensively in military working dogs in Vietnam. Because an unexplained significant decrease in sperm quality in Vietnam veterans has been observed by the Centers for Disease Control, further research is warranted if we are to clarify military service in Vietnam as a risk factor for testicular dysfunction. The testis should be made a priority site in the study of Vietnam experience-related cancers.

Narrowing the zone of uncertainty between research and development in biological warfare defense.

Although "research" is not prohibited by the Biological Weapons Convention, States Parties to the Convention have maintained the spirit of the Convention in actions relating to research. The confidence-building measures agreed to at RC2 refer to research facilities, publication of research results, and promotion of contacts between scientists engaged in research related to the Convention. However, assessment of basic research on biological agents is not a productive way to distinguish an offensive from a defensive program. Additionally, if a country were to initiate a biological weapons program, basic research on biological agents may not be necessary. For example, the extensive published research on Bacillus anthracis, both as a cause of anthrax in cattle and other species and as a biological-warfare agent, would enable any motivated group or nation to initiate a biological weapons program that could immediately advance to the development and scale-up stages. Research on biological agents for offensive purposes would be characterized by activities such as selection for growth, virulence, and toxin production; improving stability under varying environmental conditions; and selection of strains that might overcome existing means of prophylaxis and treatment. A biological program with an offensive intent would in most cases be characterized by evidence of development efforts in mass production and dissemination, which are often agent-specific. Thus, an assessment of development may distinguish offensive from defensive programs. If a country were to initiate a biological weapons research program, and were willing to risk worldwide condemnation should existence of such a program become known, it is likely that such a program would include development and production capabilities. If a country were not committed to production capability, there would be no rationale for an offensive biological research that would bring worldwide condemnation. Critics of the U.S. Biological Defense Research Program have suggested that the program could easily and quickly be turned into an offensive effort. To accomplish this, however, we have to assume that all military personnel, including the civilians employed by the Department of the Army, are unethical and willing to break the law and run the risk of placing the U.S. in a noncompliance status. The Army is under constant scrutiny by governmental agencies, by visiting scientists, by audiences at scientific meetings, by scientists who review manuscripts for publications, by news media, and by private citizens.(ABSTRACT TRUNCATED AT 400 WORDS)

Serological evidence for a high incidence of transmission of Rickettsia tsutsugamushi in two Orang Asli settlements in Peninsular Malaysia.

Two communities of Orang Asli (aborigines) in Peninsular Malaysia were observed for evidence of Rickettsia tsutsugamushi infection over periods of 1-8 mo. Sequential sera were examined for antibody by the indirect immunofluorescence test. The incidence of infection in the two self-selected populations in the two communities was calculated to be 3.9% per month and 3.2% per month.

Evidence of a serologic relationship between Ehrlichia canis and Rickettsia sennetsu.

A serologic relationship between Rickettsia sennetsu, the etiologic agent of human sennetsu rickettsiosis in western Japan, and Ehrlichia canis, the agent of canine ehrlichiosis, has been demonstrated. Using the indirect fluorescent antibody test, convalescent sera from patients with sennetsu fever reacted with Ehrlichia canis antigen. In the direct fluorescent antibody test, immunoglobulins from four patients with sennetsu rickettsiosis stained E. canis morulae in canine monocytes. This finding is significant in view of the morphologic uniqueness of the two agents and a lack of serologic relatedness with other major rickettsial agents.

Adaptation of a microimmunofluorescence test to the study of human Rickettsia tsutsugamuskh antibody.

A microimmunofluorescence (micro-IFA) test has been adapted to the study of naturally occurring antibody to Rickettsia tsutsugamushi in humans. The micro-IFA test was comparable to the present immlnofluorescent assay in sensitivity and reproducibility, but offered distinct advantages in the quantity of reagents necessary. Also the micro-IFA could be used to simultaneously titer a serum to as many as nine strains of the organism resulting in a great saving of time.

Identification and antigenic typing of Rickettsia tsutsugamushi in naturally infected chiggers (Acarina: Trombiculidae) by direct immunofluorescence.

Rickettsia tsutsugamushi organisms were detected and typed antigenically by direct immunofluorescence in mites from laboratory-maintained infected colonies of Leptotrombidium (Leptotrombidium) fletcheri and L. (L.) arenicola. Rickettsiae were identified most readily in unengorged larvae, but were also discernable in engorged larvae and all post-larval stages of the vectors.

Characterization of Rickettsia tsutsugamushi strains in two species of naturally infected, laboratory-reared chiggers.

The strains of Rickettsia tsutsugamushi found in naturally infected, laboratory-reared Leptotrombidium (Leptotrombidium) arenicola and L. (L.) fletcheri chiggers were characterized by direct immunofluorescence (FA) and by mouse and monkey virulence tests. The strains existing in the L. (L.) arenicola chiggers consisted of different combinations of TA716, TA763, TA686, Karp, and Kato. In addition to these five strains, Gilliam was found in the L. (L.) fletcheri chiggers. Results indicate that individual chiggers can be simultaneously infected with several antigenic strains of R. tsutsugamushi. Although these antigens appear to remain stable within familial lines when several generations were viewed, the antigenic patterns observed in two succeeding generations did not always correlate. This variable expression of antigens was considered to be due to a quantitative fluctuation from one generation to the next in the strains of rickettsiae combined with a lack of sensitivity of the direct FA test in detecting small numbers of antigenically different rickettsiae. Phenotypic variation was considered to be a less probable explanation. Morbidity and mortality were minimal in ICR mice fed upon by individual chiggers of either species, but infection rates were 85-99%. Tissue suspensions prepared from mice infected by L. (L.) arenicola produced higher mortality and longer duration of illness in mice than those prepared from L. (L.) fletcheri-infected mice. Silvered leaf and cynomolgus monkeys were fed upon by the two species of chiggers or inoculated with the mouse tissue suspensions. In both cases, minimal clinical responses were observed.

Febrile illness in Malaysia--an analysis of 1,629 hospitalized patients.

We studied 1,629 febrile patients from a rural area of Malaysia, and made a laboratory diagnosis in 1,025 (62.9%) cases. Scrub typhus was the most frequent diagnosis (19.3% of all illnesses) followed by typhoid and paratyphoid (7.4%); flavivirus infection (7.0%); leptospirosis (6.8%); and malaria (6.2%). The hospital mortality was very low (0.5% of all febrile patients). The high prevalence of scrub typhus in oil palm laborers (46.8% of all febrile illnesses in that group) was confirmed. In rural Malaysia, therapy with chloramphenicol or a tetracycline would be appropriate for undiagnosed patients in whom malaria has been excluded. Failure to respond to tetracycline within 48 hours would usually suggest a diagnosis of typhoid, and indicate the need for a change in therapy.

The longevity of antibody to Rickettsia tsutsugamushi in patients with confirmed scrub typhus.

Serological surveillance for up to two years of 114 patients with laboratory confirmed scrub typhus showed that antibody to Rickettsia tsutsugamushi as demonstrated by the indirect fluorescent antibody test is short-lived. The mean reversion time from mean peak titre (1:499) was 48.9 weeks and the calculated annual reversion rate to a titre less than 1:50 was 61%. This can be used to estimate attack rates based on point prevalence of antibody. The relationship between antibody prevalence and attack rates observed by other workers was confirmed using this model. The possible uses of the finding and its implications in Malaysia are briefly discussed.

Single dose doxycycline therapy for scrub typhus.

A single dose of 200 mg of doxycycline was shown to be as effective as a seven day course of tetracycline, in patients suspected of having scrub typhus. 65 (44%) of the 149 patients studied fulfilled the criteria for definite diagnosis of scrub typhus; 10 had an additional diagnosis. Rickettsia tsutsugamushi was isolated from 49 (75%) patients. There was no difference between the two treatment groups in time to defervescence, abolition of cough and headache, or in the time taken to recover well-being. There were no relapses in either group. Of the remaining 84 patients, a causal diagnosis was achieved in 52. Irrespective of a diagnosis there was no difference in apparent response to either doxycycline or tetracycline.