Aerosol transmission of foot-and-mouth disease virus Asia-1 under experimental conditions.

Foot-and-mouth disease virus (FMDV) control measures rely on understanding of virus transmission mechanisms. Direct contact between naïve and infected animals or spread by contaminated fomites is prevented by quarantines and rigorous decontamination procedures during outbreaks. Transmission of FMDV by aerosol may not be prevented by these control measures and this route of transmission may allow infection of animals at distance from the infection source. Understanding the potential for aerosol spread of specific FMDV strains is important for informing control strategies in an outbreak. Here, the potential for transmission of an FMDV Asia 1 strain between pigs and cattle by indirect aerosol exposure was evaluated in an experimental setting. Four naïve calves were exposed to aerosols emitted from three infected pigs in an adjacent room for a 10h period. Direct contact between pigs and cattle and fomite transfer between rooms was prevented. Viral titres in aerosols emitted by the infected pigs were measured to estimate the dose that calves were exposed to. One of the calves developed clinical signs of FMD, whilst there was serological evidence for spread to cattle by aerosol transmission in the remaining three calves. This highlights the possibility that this FMDV Asia 1 strain could be spread by aerosol transmission given appropriate environmental conditions should an outbreak occur in pigs. Our estimates suggest the exposure dose required for aerosol transmission was higher than has been previously quantified for other serotypes, implying that aerosols are less likely to play a significant role in transmission and spread of this FMDV strain.

Experimental pig-to-pig transmission dynamics for African swine fever virus, Georgia 2007/1 strain.

African swine fever virus (ASFV) continues to cause outbreaks in domestic pigs and wild boar in Eastern European countries. To gain insights into its transmission dynamics, we estimated the pig-to-pig basic reproduction number (R 0) for the Georgia 2007/1 ASFV strain using a stochastic susceptible-exposed-infectious-recovered (SEIR) model with parameters estimated from transmission experiments. Models showed that R 0 is 2·8 [95% confidence interval (CI) 1·3-4·8] within a pen and 1·4 (95% CI 0·6-2·4) between pens. The results furthermore suggest that ASFV genome detection in oronasal samples is an effective diagnostic tool for early detection of infection. This study provides quantitative information on transmission parameters for ASFV in domestic pigs, which are required to more effectively assess the potential impact of strategies for the control of between-farm epidemic spread in European countries.

Risk based surveillance for early detection of low pathogenic avian influenza outbreaks in layer chickens.

Current knowledge does not allow the prediction of when low pathogenic avian influenza virus (LPAIV) of the H5 and H7 subtypes infecting poultry will mutate to their highly pathogenic phenotype (HPAIV). This mutation may already take place in the first infected flock; hence early detection of LPAIV outbreaks will reduce the likelihood of pathogenicity mutations and large epidemics. The objective of this study was the development of a model for the design and evaluation of serological-surveillance programmes, with a particular focus on early detection of LPAIV infections in layer chicken flocks. Early detection is defined as the detection of an infected flock before it infects on average more than one other flock (between-flock reproduction ratio Rf<1), hence a LPAI introduction will be detected when only one or a few other flocks are infected. We used a mathematical model that investigates the required sample size and sampling frequency for early detection by taking into account the LPAIV within- and between-flock infection dynamics as well as the diagnostic performance of the serological test used. Since layer flocks are the target of the surveillance, we also explored whether the use of eggs, is a good alternative to sera, as sample commodity. The model was used to refine the current Dutch serological-surveillance programme. LPAIV transmission-risk maps were constructed and used to target a risk-based surveillance strategy. In conclusion, we present a model that can be used to explore different sampling strategies, which combined with a cost-benefit analysis would enhance surveillance programmes for low pathogenic avian influenza.

Within herd transmission and evaluation of the performance of clinical and serological diagnosis of foot-and-mouth disease in partially immune cattle herds.

The control of foot-and-mouth disease (FMD) in vaccinated populations relies upon surveillance activities such as clinical inspections (CI) and serological monitoring. New evidence to refine current surveillance guidelines has been provided by evaluating (1) the diagnostic performance of CI and serological tests for detection of FMD virus (FMDV) non-structural proteins (NSP), and (2) the within-herd transmission of the virus in partially immune cattle. Data came from 23 affected herds during an epidemic of FMDV type O in Bolivia, in 2007. All cattle (n=957) in these herds were clinically inspected and serum samples were collected one month after the last animal with clinical signs was detected. Samples were tested for the presence of antibodies against NSP using the PANAFTOSA 3ABC-ELISA test and a subset of samples were tested using the enzyme-linked immunoelectrotransfer blot assay (EITB). Data from clinical and serological diagnoses were analysed using a Bayesian model. The sensitivity Se and specificity Sp of the tests, as well as the prevalence and the within-herd reproduction ratio R of FMDV were estimated. In addition, risk factors for infection were identified. The Se of CI, the 3ABC-ELISA and the EITB tests were estimated to be 0.30, 0.88 and 0.96 respectively. The estimated Sp, in the same order, were 0.88, 0.93 and 0.97. The within-herd prevalence of infected animals ranged from 0.04 to 0.91 and R ranged from 1.02 to 2.68. It was observed that cattle coming from areas with high vaccination coverage had a lower risk of becoming infected than home-bred cattle from the affected herds, where vaccination coverage was thought to be low. Although these estimates come from herds kept under specific conditions, they provide a reference for future surveillance design and can inform simulation models for surveillance and control of FMD in similar cattle populations.

Using egg production data to quantify within-flock transmission of low pathogenic avian influenza virus in commercial layer chickens.

Even though low pathogenic avian influenza viruses (LPAIv) affect the poultry industry of several countries in the world, information about their transmission characteristics in poultry is sparse. Outbreak reports of LPAIv in layer chickens have described drops in egg production that appear to be correlated with the virus transmission dynamics. The objective of this study was to use egg production data from LPAIv infected layer flocks to quantify the within-flock transmission parameters of the virus. Egg production data from two commercial layer chicken flocks which were infected with an H7N3 LPAIv were used for this study. In addition, an isolate of the H7N3 LPAIv causing these outbreaks was used in a transmission experiment. The field and experimental estimates showed that this is a virus with high transmission characteristics. Furthermore, with the field method, the day of introduction of the virus into the flock was estimated. The method here presented uses compartmental models that assume homogeneous mixing. This method is, therefore, best suited to study transmission in commercial flocks with a litter (floor-reared) housing system. It would also perform better, when used to study transmission retrospectively, after the outbreak has finished and there is egg production data from recovered chickens. This method cannot be used when a flock was affected with a LPAIv with low transmission characteristics (R(0)<2), since the drop in egg production would be low and likely to be confounded with the expected decrease in production due to aging of the flock. Because only two flocks were used for this analysis, this study is a preliminary basis for a proof of principle that transmission parameters of LPAIv infections in layer chicken flocks could be quantified using the egg production data from affected flocks.

Transmission characteristics of low pathogenic avian influenza virus of H7N7 and H5N7 subtypes in layer chickens.

Low pathogenic avian influenza virus (LPAIv) infections of H5 and H7 subtypes in poultry are notifiable to the OIE, hence surveillance programmes are implemented. The rate at which LPAIv strains spread within a flock determines the prevalence of infected birds and the time it takes to reach that prevalence and, consequently, optimal sample size and sampling frequency. The aim of this study was to investigate the transmission characteristics of an H7N7 and an H5N7 LPAIv in layer chickens. Two transmission experiments were performed, which consisted of 30 (first experiment) and 20 (second experiment) pairs of conventional layers, respectively. At the start of the experiments, one chicken per pair was inoculated with LPAIv and the other chicken was contact-exposed. Occurrence of infection was monitored by regularly collecting tracheal and cloacal swab samples, which were examined for the presence of virus RNA by RT-PCR. The results of the test were used to estimate the transmission rate parameter (ß), the infectious period (T) and the basic reproduction ratio (R(0)). In addition, egg production and virus shedding patterns were quantified. For the H7N7 virus, the ß, T and R(0) estimates were 0.10 (95% confidence interval (CI): 0.04-0.18) day(-1), 7.1 (95% CI: 6.5-7.8) days and 0.7 (95% CI: 0.0-1.7), respectively. With the H5N7 virus, only a few inoculated chickens (5 out of 20) became infected and no transmission was observed. This study shows that transmission characteristics of LPAIv strains may vary considerably, which has to be taken into account when designing surveillance programmes.

Transmission between chickens of an H7N1 Low Pathogenic Avian Influenza virus isolated during the epidemic of 1999 in Italy.

The transmissibility of an H7N1 Low Pathogenic Avian Influenza (LPAI) virus isolated from a turkey flock during the large epidemic in Italy in 1999, was experimentally studied in chickens. Four group transmission experiments were performed. Infection and transmission were monitored by means of virus isolation on swab samples and antibody detection in serum samples. From the results of these groups, we estimated the mean infectious period at 7.7 (6.7-8.7) days, the transmission rate parameter at 0.49 (0.30-0.75) infections per infectious chicken per day and the basic reproduction ratio at 3.8 (1.3-6.3). These estimates can be used for the development of surveillance and control programmes of LPAI in poultry.

Low-pathogenic notifiable avian influenza serosurveillance and the risk of infection in poultry - a critical review of the European Union active surveillance programme (2005-2007).

BACKGROUND: Since 2003, Member States (MS) of the European Union (EU) have implemented serosurveillance programmes for low pathogenic notifiable avian influenza (LPNAI) in poultry. To date, there is the need to evaluate the surveillance activity in order to optimize the programme's surveillance design. OBJECTIVES: To evaluate MS sampling operations [sample size and targeted poultry types (PTs)] and its relation with the probability of detection and to estimate the PTs relative risk (RR) of being infected. METHODS: Reported data of the surveillance carried out from 2005 to 2007 were analyzed using: (i) descriptive indicators to characterize both MS sampling operations and its relation with the probability of detection and the LPNAI epidemiological situation, and (ii) multivariable methods to estimate each PTs RR of being infected. RESULTS: Member States sampling a higher sample size than that recommended by the EU had a significantly higher probability of detection. Poultry types with ducks & geese, game-birds, ratites and "others" had a significant higher RR of being seropositive than chicken categories. The seroprevalence in duck & geese and game-bird holdings appears to be higher than 5%, which is the EU-recommended design prevalence (DP), while in chicken and turkey categories the seroprevalence was considerably lower than 5% and with that there is the risk of missing LPNAI seropositive holdings. CONCLUSION: It is recommended that the European Commission discusses with its MS whether the results of our evaluation calls for refinement of the surveillance characteristics such as sampling frequency, the between-holding DP and MS sampling operation strategies.

Bovine trypanosomosis in the Bolivian Pantanal.

Trypanosomosis caused by Trypanosoma vivax has been a constraint for cattle production in the Bolivian lowlands, since it was introduced in 1996. Flooded areas like the Bolivian Pantanal have a suitable environment for the presence and transmission of Salivarian trypanosomes and farmers from that region often report trypanosomosis-like problems on their farms. The objective of the present study, therefore, was to characterize the epidemiology of bovine trypanosomosis in the Bolivian Pantanal. In order to achieve this objective, 202 cattle from the province of Angel Sandoval and 209 cattle from the province of German Busch were randomly sampled (the Pantanal is located in both provinces). Twenty-nine farms in both provinces were visited, the farmers interviewed, and biologic samples collected from their cattle. Samples were submitted for parasitological and PCR evaluation and the prevalence of bovine trypanosomosis was estimated for each province. Laboratory results were correlated with the sampled animals packed cell volume (PCV) and body condition (BC) scores and the observed T. vivax parasites measured for morphometry analysis. Results from this study show differences in morphometric measures between T. vivax parasites from each province. Differences between provinces were also observed in the T. vivax-related disease situation. While in Angel Sandoval the PCV and BC of T. vivax-affected animals were significantly lower than those of the T. vivax-negative animals, in German Busch no differences were observed in the PCV and BC of T. vivax-positive or negative animals. Animal prevalence of T. vivax in Angel Sandoval was 27.79% (95% CI: 14.52-44.28) and in German Busch was 19.03% (95% CI: 9.19-30.75). The T. evansi animal prevalence in each province was 0.99% (95% CI: 0.27-2.99) and 5.71% (95% CI: 2.43-12.19), respectively. Based on questionnaire and laboratory results, it was concluded that trypanosomosis is a primary constraint for cattle production in the Bolivian Pantanal.

Sensitivity of different Trypanosoma vivax specific primers for the diagnosis of livestock trypanosomosis using different DNA extraction methods.

There are several T. vivax specific primers developed for PCR diagnosis. Most of these primers were validated under different DNA extraction methods and study designs leading to heterogeneity of results. The objective of the present study was to validate PCR as a diagnostic test for T. vivax trypanosomosis by means of determining the test sensitivity of different published specific primers with different sample preparations. Four different DNA extraction methods were used to test the sensitivity of PCR with four different primer sets. DNA was extracted directly from whole blood samples, blood dried on filter papers or blood dried on FTA cards. The results showed that the sensitivity of PCR with each primer set was highly dependant of the sample preparation and DNA extraction method. The highest sensitivities for all the primers tested were determined using DNA extracted from whole blood samples, while the lowest sensitivities were obtained when DNA was extracted from filter paper preparations. To conclude, the obtained results are discussed and a protocol for diagnosis and surveillance for T. vivax trypanosomosis is recommended.

Dietary risk factors associated with the transmission of Helicobacter pylori in Lima, Peru.

The factors influencing the risk of acquisition of Helicobacter pylori infection are not well established. One hundred four children (0-17 years of age) requiring an endoscopy for the evaluation of gastrointestinal symptoms had demographic and dietary data collected and biopsy specimens of the gastric antrum stained for the identification of H. pylori. The 52 (50%) infected subjects were significantly older than the uninfected ones with no difference in gender, crowding, source of drinking water, or exposure to domestic animals. Increased prevalence of infection was associated with increased consumption of food from street vendors, and decreased consumption of fruits in the subgroup that denied consuming food from street vendors. No association was found with consumption of fish, chicken, beef, beans, vegetables, rice, cheese, milk, and unboiled water. These findings support the role of food prepared under unhygienic conditions as a probable mechanism of transmission of H. pylori in developing countries.

Evaluation of the effects of the addition of morphine sulfate to a standard Bier block solution in peripheral arm surgery.

The purpose of this study was to analyze postoperative pain differences in patients undergoing peripheral arm surgery. Differences between patients' perceived pain who received 2 mg of morphine sulfate added to the standard Bier block solution and the standard Bier block solution without morphine were studied. A quasi-experimental nonequivalent control group design was utilized. Thirty adult subjects (22 men and 8 women) ages 21 to 76 years constituted the convenience sample. Pain scores were measured by a verbal descriptor scale at the following times: upon admission to the postanesthesia care unit, at 30 minutes and 60 minutes after surgery, and at 24 hours postoperatively. A two-tailed Mann-Whitney U test was used to analyze pain scores for the two groups (P < .05). No statistically significant differences were found in postoperative pain between the group receiving a Bier block solution with 2 mg of morphine sulfate and the group with a standard Bier block solution without morphine sulfate. The mean scores for the morphine sulfate group were lower in each time period measured. This study suggests a questionable benefit for adding 2 mg of morphine sulfate to a Bier block solution. A larger sample may have yielded different results. Many issues remain undecided regarding the potential role of opioids in various regional anesthetic techniques. Further studies are warranted to investigate the peripheral effects of opioids and to understand the mechanisms of action of opioid analgesics at peripheral sites.

Helicobacter pylori infection in children with abdominal ailments in a developing country.

Helicobacter pylori commonly infects children in developing countries. To determine the frequency of this infection and its potential role in specific gastrointestinal entities, all patients requiring upper gastrointestinal endoscopy for the evaluation of abdominal ailments in a gastroenterology practice in Lima, Peru, were evaluated during a 1-year period. Gastric biopsies were obtained for each child and were stained with hematoxylin-eosin and Warthin-Starry stains. Of the 107 evaluable patients (mean age 7.4 years, 58% boys), 52 (49%) were infected. The infection rate increased with older patients (P = 0.004). Children with recurrent abdominal pain (P = 0.04), an endoscopic finding of nodular gastritis (P = 0.007), and a histologic finding of chronic active gastritis (P < 0.0001) were infected more commonly.

A randomized trial of misoprostol and oxytocin for induction of labor: safety and efficacy.

OBJECTIVE: To compare the safety and efficacy of misoprostol and oxytocin for induction of labor. METHODS: One hundred thirty women requiring induction of labor were randomized to receive either intravenous oxytocin or 100 micrograms misoprostol, administered intravaginally every 4 hours until labor was established. RESULTS: Compared with women receiving oxytocin, a greater percentage of women in the misoprostol group had Bishop scores of 3 or less (58 versus 38%, P < .05). Nonetheless, the median induction-to-delivery interval was significantly shorter (585 versus 885 minutes, P < .001) in the misoprostol group. Women in the misoprostol group were more likely to deliver vaginally within 24 hours of the start of induction (77 versus 55%, P < .002). Epidural analgesia was used more frequently in women receiving oxytocin than in those receiving misoprostol (73 versus 50%, P = .025). The total percentage of cesarean deliveries was not significantly different, although the percentage of cesarean deliveries for dystocia was lower in the misoprostol group (8 versus 21%, P = .02). Uterine tachysystole was significantly more common (70 versus 11%, P < .001) and hospital charges significantly less with misoprostol. CONCLUSION: Compared with oxytocin for labor induction, misoprostol results in a shorter induction-to-delivery interval, a reduction in the rate of cesarean delivery for dystocia, and a decreased use of epidural analgesia. Uterine tachysystole is significantly more common with the use of misoprostol.

Cost-effective communication skills training for state hospital employees.

OBJECTIVE: This study evaluated the cost-benefits of a staff communications training program designed to improve patient management skills and relieve staff stress. METHODS: The interpersonal communications program, based on the Carkhuff model, was specially designed for mental health settings. The training program focused on developing accurate empathy by teaching staff members to use appropriate cognitive and emotional components of interpersonal communication. Staff on a short-stay adult inpatient recidivist unit received the training, while those on a matched unit served as a quasi-control group. Data from routine reports from six months before and six months after training were analyzed. The main cost-benefit variables of interest were improved staff retention and patient outcomes. RESULTS AND CONCLUSIONS: The trained unit had less staff turnover, and staff members on that unit used less sick and annual leave. Fewer patients' rights complaints were filed, and fewer assaults on staff were reported. The cost-benefit analysis revealed substantial savings for the trained unit and increased expenditures for the control unit. The results suggested that training in empathic communication skills for direct care staff is a promising proactive, cost-effective approach to coping with staff stress and turnover and may also improve patient outcomes.

False positive of ADA determination in cerebrospinal fluid.

The elevation of ADA in CSF is useful as a diagnostic means for detecting tuberculous meningitis, and in other etiologies such as lymphoma, neurosarcoidosis, fulminant bacterial meningitis, cryptococcal meningitis, neurobrucellosis and AIDS. We report an increase of ADA in CSF in association with SHA. In our case the total activity of ADA was the same as that obtained in serum, which can be interpreted among the false positives of the determination.

Cardiovascular risk factors in Mexican Americans in Laredo, Texas. I. Prevalence of overweight and diabetes and distributions of serum lipids.

An epidemiologic survey of cardiovascular risk factors was carried out on a random sample of Mexican Americans living in two low income census tracts in Laredo, Texas. The prevalence of overweight was found to be intermediate between US national estimates and the rates recorded for Pima Indians. Similarly, the prevalence of fasting hyperglycemia was intermediate between the rates observed in a sample or predominantly Caucasian individuals and those observed in Pima Indians. Excess hyperglycemia in the Laredo Mexican American population compared to predominantly Caucasian populations does not appear to be due to a lower level of medical control of diabetes in the former. Rather, it probably reflects a true excess in the prevalence of diabetes. Serum cholesterol and triglyceride concentrations were also higher in Laredo Mexican Americans than in a Caucasian comparison population. Mexican Americans are of mixed European and native American ancestry. Native Americans have high rates of diabetes which could be on a genetic basis. The intermediate rates of hyperglycemia in Mexican Americans could thus have a genetic explanation. On the other hand, sociocultural determinants could be important since these are known to influence obesity which is a major precursor of diabetes.

Cardiovascular risk factors in Mexican Americans in Laredo, Texas. II. Prevalence and control of hypertension.

In recent years there has been a marked improvement in the level of hypertension control nationally in both blacks and whites. Information is still lacking, however, on the level of hypertension control in Mexican Americans. The authors carried out a cardiovascular risk factor survey on a random sample of Mexican Americans living in two low income census tracts in Laredo, Texas. The percentages of hypertensive women who had been previously diagnosed, were under treatment, and were "under control" compared favorably with national figures for blacks and whites. Corresponding percentages for men indicated that their level of diagnosis, treatment and "control" still lagged behind the national figures. The prevalence of hypertension in Laredo Project participants was intermediate between those observed in national studies for blacks and whites. This finding did not clearly emerge when comparisons were based on either blood pressure distributions or prevalence of elevated diastolic pressures. These results indicate that, because of the increasing number of "controlled" hypertensives in the population, comparisons between populations and across time can no longer be based exclusively on blood pressure measurements, but must include cases of "controlled" hypertension.