Effectiveness and Cost Efficiency of Different Surveillance Components for Proving Freedom and Early Detection of Disease: Bluetongue Serotype 8 in Cattle as Case Study for Belgium, France and the Netherlands.

Quick detection and recovery of country's freedom status remain a constant challenge in animal health surveillance. The efficacy and cost efficiency of different surveillance components in proving the absence of infection or (early) detection of bluetongue serotype 8 in cattle populations within different countries (the Netherlands, France, Belgium) using surveillance data from years 2006 and 2007 were investigated using an adapted scenario tree model approach. First, surveillance components (sentinel, yearly cross-sectional and passive clinical reporting) within each country were evaluated in terms of efficacy for substantiating freedom of infection. Yearly cross-sectional survey and passive clinical reporting performed well within each country with sensitivity of detection values ranging around 0.99. The sentinel component had a sensitivity of detection around 0.7. Secondly, how effective the components were for (early) detection of bluetongue serotype 8 and whether syndromic surveillance on reproductive performance, milk production and mortality data available from the Netherlands and Belgium could be of added value were evaluated. Epidemic curves were used to estimate the timeliness of detection. Sensitivity analysis revealed that expected within-herd prevalence and number of herds processed were the most influential parameters for proving freedom and early detection. Looking at the assumed direct costs, although total costs were low for sentinel and passive clinical surveillance components, passive clinical surveillance together with syndromic surveillance (based on reproductive performance data) turned out most cost-efficient for the detection of bluetongue serotype 8. To conclude, for emerging or re-emerging vectorborne disease that behaves such as bluetongue serotype 8, it is recommended to use passive clinical and syndromic surveillance as early detection systems for maximum cost efficiency and sensitivity. Once an infection is detected and eradicated, cross-sectional screening for substantiating freedom of infection and sentinel for monitoring the disease evolution are recommended.

Quantification of rHVT-F genome load in feather follicles by specific real-time qPCR as an indicator of NDV-specific humoral immunity induced by day-old vaccination in SPF chickens.

The purpose of this study was to look for a reliable molecular method for confirmation of uptake of recombinant turkey herpesvirus vaccine against Newcastle disease (rHVT-F) and for use as a valuable prediction tool of Newcastle disease virus (NDV)-specific immune response in chickens deprived of maternally derived antibody (MDA). A quantitative real-time polymerase chain reaction (real-time qPCR) specific to rHVT-F was developed. The method was applied to various tissue samples taken from specific pathogen free (SPF) chickens experimentally inoculated at day-old with one dose of rHVT-F vaccine over a 6-week period. Among the tested tissues, the rHVT-F vaccine was detected predominantly in the bursa of Fabricius (BF) and the lung for the first week, followed by a progressive decline from 9 days onwards. Then, an increase of genome load was observed in the feather follicles (FF) with a peak at 2 weeks, rising to a level almost 10(3)-fold greater than in the other tissues. Importantly, the rHVT-F genome load in FF appeared to be strongly correlated to the humoral immunity specific to NDV as evaluated by haemagglutination inhibition (HI) test and NDV-specific IgG, IgM and IgA ELISAs. This is the first report of quantification of rHVT-F vaccine in FF and its correlation with the induction of ND-specific immune response in chickens with no MDA. Our data indicate that the application of this real-time qPCR assay on FF samples taken from chickens in the field may be used to confirm rHVT-F vaccine administration and uptake with the important added benefit of offering a non-disruptive sampling procedure.

The impact of viral tropism and housing conditions on the transmission of three H5/H7 low pathogenic avian influenza viruses in chickens.

In this study, shedding and transmission of three H5/H7 low pathogenic avian influenza viruses (LPAIVs) in poultry was characterized and the impact of floor system on transmission was assessed. Transmission experiments were simultaneously conducted with two groups of animals housed on either a grid or a floor covered with litter. Transmission was observed for H5N2 A/Ch/Belgium/150VB/99 LPAIV. This virus was shed almost exclusively via the oropharynx and no impact of floor system was seen. Transmission was also seen for H7N1 A/Ch/Italy/1067/v99 LPAIV, which was shed via both the oropharynx and cloaca. A slight increase in transmission was seen for animals housed on litter. H5N3 A/Anas Platyrhynchos/Belgium/09-884/2008 LPAIV did not spread to susceptible animals, regardless of the floor system. This study shows that environmental factors such as floor systems used in poultry barns may act upon the transmission of LPAIVs. However, the level of influence depends on the virus under consideration and, more specifically, its principal replication sites.

Bovine tuberculosis surveillance alternatives in Belgium.

Belgium obtained the bovine tuberculosis (bTB) officially free status in 2003 (EC Decision 2003/467/EC). This study was carried out to evaluate the components of the current bTB surveillance program in Belgium and to determine the sensitivity of this program. Secondly, alternatives to optimize the bTB surveillance in accordance with European legislation (Council Directive 64/432/EEC) were evaluated. Separate scenario trees were designed for each active surveillance component of the bTB surveillance program. Data from 2005 to 2009 regarding cattle population, movement and surveillance were collected to feed the stochastic scenario tree simulation model. A total of 7,403,826 cattle movement history records were obtained for the 2,678,020 cattle from 36,059 cattle herds still active in 2009. The current surveillance program sensitivity as well as the impact of alternative surveillance protocols was simulated in a stochastic model using 10,000 iterations per simulation. The median (50% percentile) of the component sensitivities across 10,000 iterations was 0.83, 0.85, 0.99, 0.99, respectively, for (i) testing the cattle only during the winter screening, (ii) testing only imported cattle, (iii) testing only purchased cattle and (iv) testing only all slaughtered cattle. The sensitivity analysis showed that the most influential input parameter explaining the variability around the output came from the uncertainty distribution around the sensitivity of the diagnostic tests used within the bTB surveillance. Providing all animals are inspected and post mortem inspection is highly sensitive, slaughterhouse surveillance was the most effective surveillance component. If these conditions were not met, the uncertainty around the mean sensitivity of this component was important. Using an antibody ELISA at purchase and an interferon gamma test during winter screening and at import would increase greatly the sensitivity and the confidence level of Belgium's freedom from bTB infection status.

Further evidence of antigenic drift and protective efficacy afforded by a recombinant HVT-H5 vaccine against challenge with two antigenically divergent Egyptian clade 2.2.1 HPAI H5N1 strains.

In this study, we have compared the protection afforded by a recombinant turkey herpesvirus vaccine expressing the H5 gene from a clade 2.2 H5N1 strain (rHVT-H5) and a Mexican-origin H5N2 inactivated vaccine, alone or in combination, against two antigenically divergent H5N1 Egyptian strains isolated in 2007 and 2008. Our results confirm the existence of a major antigenic drift among the Egyptian H5N1 strains such that, although protection against the "classical" 2007 HPAI H5N1 Egyptian strain could be obtained with both types of vaccines, only vaccination with the rHVT-H5 vaccine protected against challenge with the "variant" 2008 HPAI H5N1 Egyptian strain.

Arthropod dermatoses acquired in the UK and overseas.

International tourism to tropical and sub-tropical areas, both to resource-poor and developed countries, has almost trebled within the past 20 years. We examined the records of patients referred to the Liverpool School of Tropical Medicine over 6 years. 46 (63%) of infestations originated in the UK. Ticks were most common in the UK (19 cases, 41%) whereas myiasis was most common in travellers (18 cases, 67%). These records suggest that whereas many overseas acquired infestations are potentially dangerous if infections are transmitted, ticks constitute the greatest risk, and both domestic and exotic species may act as disease vectors.

Management of pulmonary tuberculosis suspects with negative sputum smears and normal or minimally abnormal chest radiographs in resource-poor settings.

SETTING: Queen Elizabeth Central Hospital, Blantyre, Malawi. OBJECTIVES: 1) To determine the proportion of pulmonary tuberculosis (PTB) suspects with negative sputum smears and a normal/minimally abnormal chest radiograph (CXR) who are culture-positive for Mycobacterium tuberculosis, and 2) to determine how many develop smear or radiographic evidence of PTB (TB CXR) during follow-up. METHODS: PTB suspects with negative sputum smears and a normal/minimally abnormal CXR were given a second course of antibiotics and followed up at 3-week intervals over 3 months with repeat sputum smears and chest radiography. RESULTS: Of 79 patients (38 men and 41 women, mean age 33 years) with negative smears and a normal/minimally abnormal CXR, 16 (21%) were culture-positive for M. tuberculosis. Of 15 culture-positive patients who were alive and attended follow-up, seven (47%) developed a TB-CXR by 3 months. Of 41 culture-negative patients who were alive and attended follow-up, 13 (32%) developed a TB-CXR, including one patient who became sputum smear-positive. TB-CXRs were found only in patients with a cough. CONCLUSION: TB suspects with negative smears and normal/minimally abnormal CXRs in high human immunodeficiency virus (HIV) prevalent countries should be given a second course of antibiotics. If cough improves, patients can be advised not to return for further follow-up. If cough continues, patients should return for further follow-up with sputum smear examination and chest radiography. Approximately 50% of those who have culture-positive PTB will develop a TB-CXR by 3 months and can be identified if radiographic facilities are available.

Prevalence of tuberculosis in TB suspects with short duration of cough.

The prevalence of pulmonary tuberculosis (PTB) in patients with short duration of cough was determined. Ninety-eight adult out-patients (60 men, 38 women; mean age 32 years) at Queen Elizabeth Central Hospital, Blantyre, Malawi, who had cough for 1-3 weeks which was unresponsive to a course of antibiotics, were successfully screened by microscopy and culture of 2 or 3 sputum specimens and chest radiography; 34 (35%) had PTB. Ten patients were sputum smear-positive and 24 were smear-negative and culture-positive. There was no difference in age, gender or clinical features of general illness, respiratory disease and HIV-related disease between patients with PTB and those with no evidence of PTB. Nine patients (26%) with microbiologically confirmed tuberculosis (TB) had chest radiograph abnormalities consistent with TB, compared with 5 (8%) of patients with no microbiological evidence of TB. Certain classes of patients with a short history of cough would benefit from PTB screening strategies with the emphasis on sputum examination rather than chest radiography, which is unreliable in such patients. The classes include (i) patients with other features of TB whose cough has not improved with antibiotic therapy, (ii) seriously ill patients, and (iii) patients in high risk institutions such as prisons and refugee camps.

Autonomic neuropathy is common in human immunodeficiency virus infection.

We prospectively evaluated autonomic nervous system function in 17 consecutive ambulant patients with HIV infection [mean age (S.D.) 34.5 (5.5) years] and 17 controls matched for sex and age [31.2 (7.4) years]. A questionnaire was administered, and neurological examination and standard bedside autonomic function tests were performed. Eleven of 17 HIV-infected individuals (64.7%) had symptoms suggestive of autonomic dysfunction, particularly urogenital problems. Thirteen of 17 (76.5%) had autonomic neuropathy (one or more abnormal tests), including nine of 11 symptomatic individuals. Only two controls had any autonomic symptoms, and all had normal tests. Autonomic dysfunction is common in those with HIV infection and AIDS.