Short communication: Passive shedding of Mycobacterium avium ssp. paratuberculosis in commercial dairy goats in Brazil.

Goat farming is a low-cost alternative to dairy production in developing countries. In Brazil, goat production has increased in recent years due in part to the implementation of programs encouraging this activity. Mycobacterium avium ssp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a disease that causes chronic granulomatous enteritis in ruminants, but MAP transmission dynamics are still poorly understood in goats. In a previously published study of our research group, 10 dairy goat farms (467 animals) from Minas Gerais state were analyzed for MAP detection; 2 fecal cultures and 11 milk samples tested positive for MAP by conventional PCR and were confirmed by sequencing. Because no clinical signs were observed over 1 yr of monitoring, we hypothesized that these MAP-positive goats could be passive shedders. Thus, in the present study, 4 positive goats (4/13) from the previous study were purchased and feces and milk samples were collected for evaluation (twice, with an interval of 3 mo between tests) by culture of MAP, IS900 PCR, or both. All analyses were negative for MAP. At the last time point, blood samples were collected for ELISA, the animals were killed, and tissues collected for tissue culture and histopathology. At necropsy, no macroscopic lesions related to paratuberculosis were observed. Similarly, no histological changes were observed and MAP in samples stained by Ziehl-Neelsen was not detected. These animals were characterized as potential passive shedders with upward contamination of the teat canal by MAP. This is the first report of the passive shedding phenomenon in goats in Brazil and it highlights the importance of identifying these animals for control programs and to ensure the quality of dairy products.

Spatial disorientation in U.S. Army rotary-wing operations.

This paper describes two surveys concerning spatial disorientation (SD) in U.S. Army rotary-wing operations that sought to assess the hazard and to identify recommendations to control it. One survey was of accident records, and the other was of aircrew experiences. Both surveys highlighted the magnitude of the problem. The accident survey showed that 30% of class A to C accidents involved SD as a significant factor, while the aircrew survey showed that 78% of aircrews have been disoriented (8% to the extent that flight safety was threatened). Both surveys showed a significant increase in SD associated with combat operations. Several differences between the two surveys were noted: 90% of the reviewed accidents were thought to involve type I (unrecognized) SD compared with only 43% of the reported incidents; both pilots in a particular aircraft were considered to have been disoriented in at least 59% of accidents compared with 23% of incidents; sudden loss of visual cues ("brownout," "whiteout," or inadvertent entry to instrument meteorological conditions) accounted for 25% of SD accidents compared with 13% of incidents; and 62% of the accidents occurred at night compared with only 36% of incidents. Neither survey showed any association between SD and fatigue or other human factors. The results of both surveys suggested that crew coordination, alerting devices (e.g., audio warnings on the radar altimeter), flight information displays, and autopilot functions would be good targets for improvement.

A PCR-restriction enzyme technique for determining dengue virus subgroups within serotypes.

The polymerase chain reaction (PCR) and restriction enzyme analysis were used to develop a rapid and simple procedure for identifying geographic subgroups of dengue virus within serotypes for epidemiologic investigations. The entire structural protein region of dengue viruses was amplified and the products were digested with the endonucleases AluI or DdeI. By comparing the restriction fragment length polymorphisms (RFLPs), we recognized dengue-2 and dengue-3 subgroups that corresponded to those previously determined by oligonucleotide fingerprinting or genomic sequencing. This procedure can be performed in 2 days without the use of radioisotopes, and results can be interpreted without computer analysis. For those analyses which require only subgroup affiliations, this is a useful tool for rapidly screening multiple virus isolates.

Sickle cell anemia trait in the military aircrew population: a report from the Military Aviation Safety Subcommittee of the Aviation Safety Committee, AsMA.

The question of whether sickle cell trait (SCT) is potentially dangerous to military aircrew personnel who have it and, consequently, whether such individuals should be allowed to fly in military aircraft is a very emotional issue. This article traces the evolution of how the U.S. military has dealt with the problem, and the present status of individuals with SCT in the U.S. military aviation community. Extensive studies and means for subjectively evaluating the problem were instituted by the Department of Defense in 1981, after making the decision not to restrict aircrew with the trait from aviation duties. All research projects and educational programs were abruptly stopped in 1985. Today, there are no actual restrictions on individuals with SCT for duty in the aviation and diving communities.