A prolonged outbreak of ornithosis in duck processors.

In 1985 an outbreak of ornithosis affected 13 of 80 (16%) workers in a duck-processing plant. New employees were three times more likely to become cases than established employees. The highest attack rate was in those on the production line. Following the outbreak, an occupational health scheme was set up to monitor the health of new recruits to the company. Serological evidence of recent infection was demonstrated in 18 of 37 (49%) new employees tested in the first 3 months of employment. Five (14%) also had clinical evidence of ornithosis. Veterinary investigation of the ducks demonstrated a high proportion with asymptomatic chlamydial infection. It is suggested that ornithosis may be more common in duck processors than is currently supposed. Strategies to reduce occupational risks are discussed.     

The development and evaluation of a mu-capture ELISA detecting Chlamydia-specific IgM

A mu-capture enzyme-linked immunosorbent assay (ELISA) for detecting chlamydia-specific IgM was developed by use of the heat stable, lipopolysaccharide group-specific antigen and an alkaline phosphatase-labelled anti-chlamydia group-specific monoclonal antibody conjugate. The test was used to study the serological response in chlamydial respiratory tract infection among patients with acute respiratory tract symptoms in Cambridgeshire during the past 7 years. Results were compared with those of the complement fixation test (CFT) in routine use as well as those of a whole inclusion indirect immunofluorescence (WIF) test for IgM. Correlation between results of the mu-capture ELISA and those of the WIF test was 87.5%. The percentage of patients in whom specific IgM was found fell with increasing age. This may be due to lack of recall of IgM as a response to reinfection. Chlamydia-specific IgM was more likely to be detected when the CFT titre was greater than or equal to 64 and was rarely detected more than 6 months after the onset of symptoms. However, several patients less than 20 years of age were found to have specific IgM with CF antibody titres less than 64. We have found the mu-capture ELISA a useful test for the diagnosis of respiratory tract chlamydial infections, particularly in younger patients.     

Cytomegalovirus pneumonitis and bone marrow transplantation: identification of a specific high risk group.

AIMS--To study the association between cytomegalovirus (CMV) excretion and interstitial pneumonitis in allogeneic bone marrow transplant (BMT) recipients, with reference to donor and recipient CMV antibody response. METHODS--The incidence of CMV excretion was prospectively studied in 62 allogeneic bone marrow transplantations performed on adults and children. All recipients received CMV seronegative blood products. Prophylaxis with high dose acyclovir and CMV immune globulin was given to high risk patients (donor or recipient, or both, CMV seropositive). RESULTS--CMV excretion was detected in eight of 26 (31%) high risk patients but in only one of 36 low risk patients (donor and recipient both CMV seronegative). Five of the eight (63%) excretors in the high risk category developed CMV, of whom four (80%) belonged to the seropositive recipient/seronegative donor group, and included the three CMV seropositive recipients whose CMV complement fixation antibody titres were 64 or greater before transplantation. CONCLUSIONS--These findings suggest that there is a subgroup of patients at especially high risk of developing CMV.     

Group C rotavirus associated with fatal enteritis in a family outbreak

A family outbreak of gastroenteritis involving three adults and three children is described in which diarrhoea and vomiting were the main clinical features. One infant died in whom no pathogens could be detected in either small or large intestinal postmortem samples. Stool samples from two symptomatic siblings contained rotaviruses as demonstrated by electron microscopy. Both of these faecal samples were negative when assayed in a group A specific rotavirus enzyme-linked immunosorbent assay (ELISA) and subsequent genomic analysis of these rotaviruses was suggestive of group C rotavirus. Serological evidence showed that these atypical rotaviruses were members of serogroup C. Other atypical rotaviruses in faecal samples from sporadic cases in symptomatic children were detected over a similar time period and location. These had electrophoretic RNA profiles similar to those in the family outbreak. Furthermore, seroepidemiological studies detected group C rotavirus antibody in blood donors resident in the location of the family outbreak.     

Amphetamine's effects on food consumption and body weight: the role of adaptive processes

Three experiments were conducted to characterize the time course of amphetamine's effects on food consumption using procedures that would allow both decreases and increases in eating to be evident relative to control levels. In Experiment 1 we measured eating over 12 postinjection hr in rats. Orderly changes in within-day temporal patterns of eating over the 12 days of amphetamine administration suggest the role of conditioned adaptive processes. In Experiment 2, animals were not presented food until 2 hr after drug administration. Initial anorexia and subsequent hyperphagia were produced by repeated administration of amphetamine. Experiment 3 assessed both within-day and over-day changes in body weight and food consumption and showed that in addition to the drug's anorectic effect, amphetamine also reduces body weight via other mechanisms. In interpreting tolerance to anorectic drugs, it is necessary to evaluate such changes in body weight that indicate shifts in hunger that occur over days as well as shifts in within-day temporal patterns of eating that indicate the presence of conditioned adaptive changes. It is proposed that these two adaptive mechanisms account for pharmacodynamic tolerance.     

Characterizing withdrawal in rats following repeated drug administration using an amphetamine-vehicle-haloperidol drug discrimination

Rationale: Previous research using an amphetamine (AM)-haloperidol (HA) drug- drug discrimination task has shown that predominant responding on the HA-appropriate lever occurs 24 h after a single or multiple administrations of 10 mg/kg AM. Conversely, rebound responding on the AM-appropriate lever occurs following single or multiple administrations of 1 mg/kg HA. HA-appropriate responding was also observed 24 h following a single injection of AM using a three-lever, AM-vehicle-HA discrimination task. However, a single administration of HA did not produce robust rebound responding on the AM-appropriate lever. The present studies seek to clarify the discrepancy between responding following HA in the two- and three-choice tasks. Objective: Experiment 1 examined the extent of rebound responding that could be achieved following ten daily administrations of either 10 mg/kg AM or 1 mg/kg HA. Experiment 2 explored potential differences between the two- and three-choice tasks in characterizing the post-HA cue. Methods: Animals were trained to discriminate 0.35 mg/kg AM, vehicle, and 0.033 mg/kg HA. In experiment 1, animals received ten daily injections of 10 mg/kg AM, vehicle, or 1 mg/kg HA, and were tested 24 h after the final injection, and again 8, 15, and 22 days post-treatment. In experiment 2, animals were retrained and then treated daily with either vehicle or 1.0 mg/kg HA for 10 days, and then tested 24 h after the final injection, and again 5 and 11 days post-treatment, with either all three levers or with only the AM- and HA-appropriate levers available. Results: In experiment 1, multiple injections of AM produced robust HA lever responding, which is consistent with results from previous studies that used the two-choice, AM-HA discrimination task. However, multiple injections of HA did not produce predominant responding on the AM-appropriate lever. In experiment 2, animals treated with either vehicle or HA responded predominantly on the vehicle-appropriate lever when tested with all three levers present. When tested with the vehicle lever removed, however, animals treated with vehicle responded predominantly on the HA-appropriate lever, whereas those treated with HA responded predominantly on the AM-appropriate lever. Conclusions: These results suggest that the two-choice and three-choice task used here differ in how the post-HA withdrawal cue is characterized. This finding emphasizes the importance of knowing the relative locations of the agonist-, vehicle-, and antagonist-produced cues on the interoceptive stimulus continuum established by discrimination training. Received: 3 December 1997/Final version: 16 November 1998