Identification of prognostic factors for survival in patients with metastatic gastric adenocarcinoma in a Mexican population.

INTRODUCTION AND AIMS: Gastric adenocarcinoma is among the high-ranking tumors, with respect to frequency and mortality, worldwide. The inflammatory process and immune system activity are associated with oncologic control. Our aim was to identify whether the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and other variables are prognostic factors for survival in patients with metastatic gastric cancer in a Mexican population. MATERIAL AND METHODS: Patients diagnosed with metastatic gastric adenocarcinoma, hospitalized within the time frame of December 2011 to 2021, were analyzed. The NLR, PLR, and albumin and hemoglobin levels obtained from blood samples were calculated. Functional status (ECOG and Karnofsky), sex, histology, and the presence of signet ring cells were also considered possible prognostic factors. Each factor's prognostic value for overall survival was determined through univariate and multivariate analyses. RESULTS: The study included 956 patients diagnosed with metastatic gastric cancer, of whom 494 (51.7%) were men and 462 (48.3%) were women. The main histologic finding was diffuse adenocarcinoma (n = 619, 64.7%), followed by intestinal adenocarcinoma (n = 293, 30.6%), and the presence of signet ring cells was found in 659 (68.9%) patients. Diagnostic laparoscopy was performed on 238 patients (24.9%) to confirm peritoneal carcinomatosis. The multivariate analysis showed that an NLR above 3.2 (HR 1.51, 95% CI 1.27-1.8; p < 0.001), albumin below 3.5 g/dl (HR 1.25, CI 1.06-1.47; p = 0.006), and an ECOG performance status of 2 or higher (HR 1.39, CI 1.10-1.76; p = 0.005) were independent factors that predicted a lower survival rate, whereas a Karnofsky score above 70% (HR 0.69, CI 0.53-0.91; p = 0.008) was associated with a better survival rate. Lastly, the PLR was not statistically significant in the multivariate analysis. CONCLUSIONS: The NLR, nutritional status assessed through albumin measurement, and functional status can act as independent prognostic survival factors in hospitalized Mexican patients diagnosed with metastatic gastric adenocarcinoma and be taken into account during therapeutic decision-making.

Prevalence of primary eosinophilic colitis in patients with chronic diarrhea and diarrhea-predominant irritable bowel syndrome.

INTRODUCTION: Primary eosinophilic colitis (PEC) is an inflammatory disease caused by the infiltration of eosinophils into the mucosa of the colon, determined after having ruled out other possible causes. It is characterized by abdominal pain and diarrhea and its prevalence is unknown. AIMS: To know the prevalence of PEC in patients with chronic diarrhea and in those with clinical criteria for diarrhea-predominant irritable bowel syndrome (IBS-D). PATIENTS AND METHODS: All patients with chronic noninflammatory diarrhea that were consecutively seen over a decade were studied through colonoscopy, with systematic biopsy. Patients with a known or decompensated organic disease, alarm features, abnormal minimal laboratory test results, and factors associated with eosinophilia were excluded. Patients with the clinical criteria for IBS-D (Rome III) were selected from the general group. Eosinophilic colitis was defined as the presence of > 35 eosinophils/100 epithelial cells per field in any of the segments. RESULTS: From the 683 patients seen, a total of 545 patients (361 women) were included in the study. Twenty-two cases of PEC were detected, resulting in a prevalence of 4.0%. A total of 343 patients had IBS-D criteria (223 women), with 16 cases of PEC detected, for a prevalence of 4.7%. Colonoscopy was normal, or almost normal, in all the PEC cases detected. CONCLUSIONS: The prevalence of PEC was 4.0% in the patients with chronic diarrhea and 4.7% in the patients with IBS-D. Peripheral eosinophilia appeared to be the main distinctive clinical characteristic, but systematic biopsy was essential for making the diagnosis.

Prevalence of primary eosinophilic colitis in patients with chronic diarrhea and diarrhea-predominant irritable bowel syndrome. / Prevalencia de colitis eosinofílica primaria en pacientes con diarrea crónica y síndrome de intestino irritable con predominio de diarrea.

INTRODUCTION: Primary eosinophilic colitis (PEC) is an inflammatory disease caused by the infiltration of eosinophils into the mucosa of the colon, determined after having ruled out other possible causes. It is characterized by abdominal pain and diarrhea and its prevalence is unknown. AIMS: To know the prevalence of PEC in patients with chronic diarrhea and in those with clinical criteria for diarrhea-predominant irritable bowel syndrome (IBS-D). PATIENTS AND METHODS: All patients with chronic noninflammatory diarrhea that were consecutively seen over a decade were studied through colonoscopy, with systematic biopsy. Patients with a known or decompensated organic disease, alarm features, abnormal minimal laboratory test results, and factors associated with eosinophilia were excluded. Patients with the clinical criteria for IBS-D (Rome III) were selected from the general group. Eosinophilic colitis was defined as the presence of>35eosinophils/100 epithelial cells per field in any of the segments. RESULTS: From the 683 patients seen, a total of 545 patients (361 women) were included in the study. Twenty-two cases of PEC were detected, resulting in a prevalence of 4.0%. A total of 343 patients had IBS-D criteria (223 women), with 16 cases of PEC detected, for a prevalence of 4.7%. Colonoscopy was normal, or almost normal, in all the PEC cases detected. CONCLUSIONS: The prevalence of PEC was 4.0% in the patients with chronic diarrhea and 4.7% in the patients with IBS-D. Peripheral eosinophilia appeared to be the main distinctive clinical characteristic, but systematic biopsy was essential for making the diagnosis.

Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico.

AIMS: To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico. METHODS AND RESULTS: Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l-1 ). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41. CONCLUSIONS: These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.

Placenta previa total acreta complicada con ruptura prematura de membranas pretérmino: reporte de un caso / Total placenta praevia accreta complicated with preterm premature rupture of membranes: A case report

Resumen ANTECEDENTES La incidencia de acretismo placentario se ha elevado en países industrializados debido al incremento en la tasa de cesáreas. La ruptura prematura de membranas pretérmino se asocia con complicaciones en 3% de todos los embarazos. En la actualidad no existen publicaciones que documenten la atención médica de ambas alteraciones en conjunto. CASO CLÍNICO Paciente de 31 años, en curso del segundo embarazo (30.2 semanas de gestación), que acudió al servicio médico por salida de líquido transvaginal. Se confirmó la ruptura prematura de membranas pretérmino por cristalografía y determinación de microglobulina alfa 1 placentaria por tira reactiva Amnisure®. La valoración de los médicos del servicio de Medicina Materno-Fetal fue: placenta previa total, con lagunas placentarias y flujo turbulento, grosor miometrial menor de 1 mm y pérdida de la interfase deciduomiometrial. Después de comprobar el bienestar fetal se inició el tratamiento conservador de la ruptura prematura de membranas pretérmino. Se decidió finalizar el embarazo a las 31 semanas, debido a que se confirmó el inicio del trabajo de parto y actividad uterina normal; se efectuó cesárea-histerectomía sin complicaciones maternas. CONCLUSIÓN La placenta previa total con datos de acretismo, concomitante con ruptura prematura de membranas pretérmino, es una complicación poco común. Estas pacientes deben recibir tratamiento conservador y adecuada vigilancia materno-fetal. A pesar de los buenos resultados obtenidos en este caso, se requiere mayor evidencia para indicar el tratamiento conservador en estas pacientes.

Abstract BACKGROUND The incidence of placental accreta has increased in industrialized countries, due to the increase in the rate of cesarean sections. On the other hand, the premature rupture of membranes (PPROM), complicate approximately 3% of all pregnancies and is associated mainly with neonatal complications related to prematurity. At present, there is no documented evidence in the medical literature of the approach of both pathologies together. CLINICAL CASE 31-year-old woman at 30.2 weeks' gestation in her second pregnancy is admitted to the hospital with vaginal discharge. PROM is confirmed by fern-type crystallization and quantification of placental alpha macroglobulin-1 (PAMG-1) microglobulin by Amnisure® test strip. Medical assessment is performed by the maternal-fetal specialists, finding complete placenta praevia with the presence of vascular lacunae with turbulent lacunar flow, myometrium thickness < 1mm and loss of the clear space. Fetal well-being is confirmed and conservative management of PPROM is initiated. Obstetric delivery is conducted at 31 weeks of gestation with Caesarean section - Hysterectomy without complications. CONCLUSIONS The premature rupture of membranes in presence of placenta accreta is a rare complication. In this patients, conservative management is a suitable alternative, with an appropriate maternal and fetal surveillance. More evidence is required to indicate the conservative treatment in these patients.

Factores de riesgo para accidente vascular encefálico en un hospital universitario / Cerebrovascular risk factors seen in a university hospital

INTRODUCCIÓN: Los factores de riesgo (FR) para accidente vascular encefálico (AVE) pediátrico difieren del adulto e incluyen un amplio rango de enfermedades, como pueden ser cardiopatías, infecciones, leucemias y errores congénitos del metabolismo. OBJETIVOS: Describir FR en AVE isquémico en población pediátrica y explorar asociación de los FR con edad, sexo y tipo de AVE. Pacientes y método: Se analizaron 114 casos pediátricos con AVE isquémico ocurridos entre enero del 2003 y julio del 2012. Los FR se estratificaron en 6 categorías, los AVE isquémicos se clasificaron como arterial y venoso. Se compararon los FR con edad, sexo y tipo de infarto (chi al cuadrado y odds ratio). RESULTADOS: La mediana de edad fue 2,5 años, 74 (62,2%) hombres. El 7,9% de los pacientes no tenía FR identificable y el 67% tenía más de uno. La mayor frecuencia de FR fue: enfermedades sistémicas agudas (56,1%), cardiopatías (35,1%) y enfermedades crónicas sistémicas (29,8%). Hubo asociación estadísticamente significativa entre FR enfermedad sistémica aguda y edad menor de 5 años (p < 0,001) y entre enfermedad crónica sistémica y edad mayor o igual a 5 años (p < 0,02). El FR cardiopatía se asoció a infarto arterial (p < 0,05) y el FR enfermedad aguda de cabeza y cuello con infarto venoso (p < 0,05). CONCLUSIONES: Los FR de AVE isquémico en la población pediátrica son múltiples y algunos de ellos se asocian a edades específicas y tipo de AVE. La detección de estos factores permitirá la prevención primaria en la población de riesgo así como un diagnóstico y tratamiento precoz, haciendo igualmente posible la prevención de recurrencias

INTRODUCTION: Risk factors (RF) in pediatric stroke differ from those of adults, and they include a wide range of diseases such as heart disease, infections, leukemias, and inborn errors of metabolism. OBJECTIVES: To describe RF for ischemic stroke in a pediatric population, and to examine the relationship of RF with age, sex and type of stroke. PATIENTS AND METHODS: An analysis was made of database of 114 children and adolescents with ischemic stroke from January 2003 to July 2012. Risk factors were stratified into 6 categories and ischemic strokes were classified as arterial and venous. We compared the RF with age, sex, and type of stroke (chi2 and OR). RESULTS: The median age was 2.5 years, with 74 (62.2%) males. No RF was identified in 7.9% of patients, and 67% had more than one RF. The most common RF were acute systemic diseases (56.1%), heart disease (35.1%), and chronic systemic diseases (29.8%). There was a statistically significant association between acute systemic disease and age less than 5 years (P<0.001), and between chronic systemic disease and age 5 years or more (P<.02). The RF of heart disease was associated with arterial infarction (P<0.05), and the acute head and neck disease RF was associated with venous infarction (P<0.05). CONCLUSIONS: The RF for ischemic stroke are multiple in the pediatric population, and some of them are associated with a specific age and type of stroke. The detection of these factors may help in the primary prevention of people at risk, an early diagnosis, and treatment and prevention of recurrences

[Cerebrovascular risk factors seen in a university hospital]. / Factores de riesgo para accidente vascular encefálico en un hospital universitario.

INTRODUCTION: Risk factors (RF) in pediatric stroke differ from those of adults, and they include a wide range of diseases such as heart disease, infections, leukemias, and inborn errors of metabolism. OBJECTIVES: To describe RF for ischemic stroke in a pediatric population, and to examine the relationship of RF with age, sex and type of stroke. PATIENTS AND METHODS: An analysis was made of database of 114 children and adolescents with ischemic stroke from January 2003 to July 2012. Risk factors were stratified into 6 categories and ischemic strokes were classified as arterial and venous. We compared the RF with age, sex, and type of stroke (chi2 and OR). RESULTS: The median age was 2.5 years, with 74 (62.2%) males. No RF was identified in 7.9% of patients, and 67% had more than one RF. The most common RF were acute systemic diseases (56.1%), heart disease (35.1%), and chronic systemic diseases (29.8%). There was a statistically significant association between acute systemic disease and age less than 5 years (P<.001), and between chronic systemic disease and age 5 years or more (P<.02). The RF of heart disease was associated with arterial infarction (P<.05), and the acute head and neck disease RF was associated with venous infarction (P<.05). CONCLUSIONS: The RF for ischemic stroke are multiple in the pediatric population, and some of them are associated with a specific age and type of stroke. The detection of these factors may help in the primary prevention of people at risk, an early diagnosis, and treatment and prevention of recurrences.

Surveillance strategies for foot and mouth disease to prove absence of disease and absence of viral circulation.

Free trade of animals and their products is based on the international or bilateral recognition of the health status of the animal populations being traded. This recognition is based on documentation of their health status by the exporting country, based on the results of continuing surveillance. According to the Terrestrial Animal Health Code of the World Organisation for Animal Health (OIE), this may be based on various methods of surveillance, such as: documenting non-specific surveillance (clinical surveillance, passive notification of suspect cases, etc.); documenting activities that increase the sensitivity of non-specific surveillance (training activities, rewards/sanctions for notification/failure to notify, etc.); documenting all specific surveillance and its results (random surveys, targeted and risk-based surveillance, convenience-testing activities, etc.). Usually, the infection is the subject of the declaration of freedom. While clinical and passive surveillance can provide a high level of confidence that foot and mouth disease (FMD) infection is absent, this is not the case in vaccinated populations. In these populations, specific surveillance becomes much more important than non-specific clinical surveillance. Specific surveillance is severely restricted by the performance of the test(s) employed. The imperfect specificity of any serological test is further complicated when techniques to differentiate infected from vaccinated animals (DIVA) are used, because imperfect purification of the antigen used for vaccination may foster the production of undesired antibodies in the vaccinated animals. The authors discuss various approaches to overcome this problem; their merits and flaws in documenting the absence of infection or virus circulation for animal diseases in general, and for FMD in particular. Particular attention is paid to finding methods that can be applied in a variety of epidemiological conditions and organisational structures, since these vary greatly among OIE Members.

The role of models in estimating consequences as part of the risk assessment process.

The degree of disease risk represented by the introduction, spread, or establishment of one or several diseases through the importation of animals and animal products is assessed by importing countries through an analysis of risk. The components of a risk analysis include hazard identification, risk assessment, risk management, and risk communication. A risk assessment starts with identification of the hazard(s) and then continues with four interrelated steps: release assessment, exposure assessment, consequence assessment, and risk estimation. Risk assessments may be either qualitative or quantitative. This paper describes how, through the integration of epidemiological and economic models, the potential adverse biological and economic consequences of exposure can be quantified.

Tratamiento de una lesión endoperiodontal tipo III (combinada o verdadera): reporte de un caso / Treatment of type III periodontal-endodontic lesion (combined or true): a case report

Se presenta un caso clínico de una lesión endoperiodontal tipo III (combinada o verdadera) en un paciente de sexo femenino de 41 años de edad sin antecedentes sistémicos. La paciente fue derivada del Curso de Especialización en Periodoncia de la Escuela de Graduados de la Universidad de Chile debido a una lesión periapical en la pieza 3.6. El pronóstico en este tipo de lesiones es dudoso, ya que es necesario que se efectúe el tratamiento endodóntico así como el periodontal, y el resultado recae más en el tratamiento periodontal. La pieza fue tratada endodónticamente dejando medicamento intraconducto a base de Clorhexidina al 2 por ciento en gel por 7 días. Una vez obturado el diente se citó a la paciente 3 meses después para un control radiográfico. Actualmente el diente está totalmente asintomático, sin movilidad y con señales de reparación.

We report a case of a type III periodontal-endodontic lesion (combined or true) in a 41-year-old female patient without systemic history. The patient was transferred from the Specialization Course in Periodontology at the Graduate School of the University of Chile due to a periapical lesion in the tooth 3.6. The prognosis for this type of lesion is uncertain, since it is necessary to perform endodontic and periodontal treatment, and the result depends more on the periodontal treatment. The piece was treated endodontically leaving intracanal medication based on 2 percent Chlorhexidine gel for 7 days. Once the tooth obturated, we gave the patient an appointment 3 months later for a control radiography. Currently, the tooth is completely asymptomatic, without mobility and with signs of repair.

Characterization of Rhynchosia yellow mosaic Yucatan virus, a new recombinant begomovirus associated with two fabaceous weeds in Yucatan, Mexico.

Rhynchosia minima (L.) DC. (Fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in Yucatan, México [1]. To characterize the begomovirus infecting these plants, the complete bipartite genome was cloned and sequenced. Sequence comparisons indicated that the virus was distinct from all other begomoviruses known to date, including those previously identified from symptomatic R. minima, and the name Rhynchosia yellow mosaic Yucatan virus (RhYMYuV) is proposed. Pairwise comparisons indicated that RhYMYuV DNA-A [2,597 nt, (EU021216)] and DNA-B [2,542 nt, (FJ792608)] components shared the highest nt sequence identity with Cabbage leaf curl virus (CaLCuV), 87% for component A and 71% for component B. Phylogenetic analysis indicated that both components of RhYMYuV are most closely related to other New World begomoviruses, having as closest relatives immediate outliers to the major Squash leaf curl virus (SLCV) clade. Recombination analysis of the RhYMYuV genome indicated that the DNA-A component has arisen through intermolecular recombination. R. minima plants inoculated with the monomeric clones developed a bright yellow mosaic similar to symptoms observed in naturally infected plants, confirming that the clones were infectious. Nicotiana benthamiana plants biolistically inoculated with monomeric clones developed curling and chlorosis in the newly emerging leaves. RhYMYuV was also detected in symptomatic Desmodium sect. Scorpiurus Benth. (Fabaceae) that were collected near the RhYMYuV-infected plants.

First Report of Okra yellow mosaic Mexico virus in Okra in the United States.

During the okra growing season from August to November of 2009, symptoms reminiscent of geminivirus infection were observed on 75% of 'Green Emerald' Abelmoschus esculentus (L.) Moench, plants in a 0.2-km2 field in Hidalgo County, TX. Visible symptoms consisted of irregular yellow patches on leaves, distinctive yellow borders on leaf edges, and chlorosis of subsequently developing leaves. The whitefly vector of begomoviruses, Bemisia tabaci (Genn.), infested okra plants in the early growth stages during late July 2009. Total DNA was isolated from the leaves of three symptomatic okra plant samples (1) and used as the PCR template to amplify a 575-bp fragment of the coat protein gene (CP) using the universal begomovirus primers AV494 and AC1048 (2). PCR products of the expected size were cloned into the pGEM-T Easy (Promega, Madison, WI) and sequenced using the universal M13F and M13 R primers. ClustalV alignment indicated 99 to 100% shared nucleotide (nt) identity, and BLAST analysis revealed that the closest relative was Okra yellow mosaic Mexico virus - Tetekalitla (OkYMMV) (GenBank Accession No. EF591631) at 98%. To amplify the full-length DNA-A and a possible cognate DNA-B component, one plant that was positive by CP-PCR and DNA sequencing was selected for further analysis. Total DNA from this plant was used as template for a second detection method that consisted of rolling circle amplification (RCA) using the TempliPhi 100 Amplification System (GE Healthcare). RCA is a non-sequence-specific approach that permits amplification of circular DNA. The RCA products were linearized to release unit length ~2.6 kb DNA-A and DNA-B components using BamHI, and EcoRI, respectively. These products were cloned into pGEM3zf+ (Promega) and sequenced using M13F and M13 R primers and then by primer walking (>300 base overlap). Full-length DNA-A and DNA-B components were obtained, respectively, at 2,613 bp (GenBank Accession No. HM035059) and 2,594 bp (GenBank Accession No HM035060). Alignment of the DNA-A component using ClustalV (MegAlign, DNASTAR, Madison, WI) with begomoviral sequences available in GenBank indicated that it was 99% identical to OkYMMV DNA-A (GenBank Accession No. DQ022611). The closest relative to the DNA-B component (ClustalV) was Sida golden mosaic virus (SiGMV) (GenBank Accession No. AJ250731) at 73%. The nt identity of the 172-nt 'common region' present in the DNA-A and DNA-B components was 99%, and the iterons (predicted Rep binding motif) were identical for the two components, indicating that they are a cognate pair. The genome organization was typical of other New World bipartite begomoviruses. The economic losses due to infection by this virus could not be determined because an early freeze killed the plants. Hidalgo County is adjacent to Tamaulipas, Mexico, where ~50 km2 of okra are grown and the whitefly vector is also present. The identification of OkYMMV based on two independent detection methods, and the presence of begomovirus-like symptoms together with the whitefly vector, provide robust evidence for the association of OkYMMV-TX with diseased okra plants. To our knowledge, this is the first report of OkYMMV-TX infecting okra crops in Texas and in the continental United States. References: (1) J. J. Doyle and J. L. Doyle. Focus 12:13, 1990. (2) S. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.

Laser-induced micron and submicron ordering effects in quasi-percolated nanostructured silver thin films.

Quasi-percolated nanostructured silver thin films are used as the starting morphology for inducing simultaneously changes in shape and ordering effects by laser irradiation. The complex fingered nanostructures are transformed into nanospheres which in turn are arranged in micro-circular patterns when irradiated through a pinhole. These transformations are characterized by transmission electron microscopy and atomic force microscopy. The observed effects are explained using Fresnel diffraction theory. Good agreement with the experimental results is obtained. These results suggest that precise patterning engineering can be achieved through control of the spatial parameters such as the pinhole diameter and the distance from the mask to the sample.

Compartmentalisation in aquaculture production systems.

Compartmentalisation is a new tool for disease management within a country. In aquaculture, the successful application of compartmentalisation is largely dependent on the system of production and the epidemiology of the disease(s) for which the compartment is being defined. Therefore, compartmentalisation may not be universally applicable across all systems and diseases. The paper examines the implementation of the concept, providing examples of specific industries, and discusses the application of hazard analysis and critical control points (HACCP) to the biosecurity of the system. The role of compartmentalisation in the management of aquaculture disease emergencies is also discussed.

The role of diagnostic laboratories in support of animal disease surveillance systems.

Diagnostic laboratories are an essential component of animal disease surveillance systems. To understand the occurrence of disease in populations, surveillance systems rely on random or targeted surveys using three approaches: clinical, serological and virological surveillance. Clinical surveillance is the basis for early detection of disease and is usually centered on the detection of syndromes and clinical findings requiring confirmation by diagnostic laboratories. Although most of the tests applied usually perform to an acceptable standard, several have not been properly validated in terms of their diagnostic sensitivity and specificity. Sensitivity and specificity estimates can vary according to local conditions and, ideally, should be determined by national laboratories where the tests are to be applied. The importance of sensitivity and specificity estimates in the design and interpretation of statistically based surveys and risk analysis is fundamental to establish appropriate disease control and prevention strategies. The World Organisation for Animal Health's (OIE) network of reference laboratories acts as centers of expertise for the diagnosis of OIE listed diseases and have a role in promoting the validation of OIE prescribed tests for international trade. This paper discusses the importance of the epidemiological evaluation of diagnostic tests and the role of the OIE Reference Laboratories and Collaborating Centres in this process.

Assessing the probability of the presence of low pathogenicity avian influenza virus in exported chicken meat.

Avian influenza (AI) is a disease of concern for the poultry industry. In its highly pathogenic form, AI viruses (AIVs) can cause a high morbidity and case fatality rate as well as severe economic consequences. Low pathogenic AIVs (LPAIVs), in contrast, only cause localized infections in the respiratory and gastrointestinal tracts of affected birds. Although there is apparently sufficient scientific evidence documenting the absence of LPAIV in poultry meat, several countries still place restrictions for international trade of poultry meat on LPAIV-infected countries. These restrictions are extremely trade disruptive and entail significant losses to the poultry industry. This article presents a quantitative approach to assess the probability of LPAIV presence in chicken meat and provides a model that can be tailored to reflect the epidemiology of LPAIV and surveillance systems in different countries. Results show that the probability of introducing LPAIV through chicken meat imports is insignificant.

Surveillance and compartmentalisation as a tool to control avian influenza.

Surveillance for avian influenza can have several objectives. Generally, these are to detect the presence of infection or to declare disease freedom. Claims for disease freedom can refer to an entire country, a zone within a country, or a compartment. Disease freedom cannot be demonstrated absolutely; however, through a multi-pronged approach employing different surveillance strategies, sufficient confidence in the absence of infection can be achieved. The recently developed OIE guidelines for surveillance for avian influenza offer different approaches to meet these goals. The guidelines are not intended to be prescriptive but rather offer options that countries may apply depending on their epidemiological situation. Compartmentalisation is a new concept that allows the recognition of populations of different health status based on management as opposed to geographic factors (regionalisation). A proposed approach for the application of this novel concept is presented.