Cocirculation of avian H9N2 and contemporary "human" H3N2 influenza A viruses in pigs in southeastern China: potential for genetic reassortment?

Pigs are permissive to both human and avian influenza viruses and have been proposed to be an intermediate host for the genesis of pandemic influenza viruses through reassortment or adaptation of avian viruses. Prospective virological surveillance carried out between March 1998 and June 2000 in Hong Kong, Special Administrative Region, People's Republic of China, on pigs imported from southeastern China, provides the first evidence of interspecies transmission of avian H9N2 viruses to pigs and documents their cocirculation with contemporary human H3N2 (A/Sydney/5/97-like, Sydney97-like) viruses. All gene segments of the porcine H9N2 viruses were closely related to viruses similar to chicken/Beijing/1/94 (H9N2), duck/Hong Kong/Y280/97 (H9N2), and the descendants of the latter virus lineage. Phylogenetic analysis suggested that repeated interspecies transmission events had occurred from the avian host to pigs. The Sydney97-like (H3N2) viruses isolated from pigs were related closely to contemporary human H3N2 viruses in all gene segments and had not undergone genetic reassortment. Cocirculation of avian H9N2 and human H3N2 viruses in pigs provides an opportunity for genetic reassortment leading to the emergence of viruses with pandemic potential.

Mapping between SNOMED RT and Clinical terms version 3: a key component of the SNOMED CT development process.

SNOMED RT and Clinical Terms Version 3 are two large, controlled medical terminologies that are being merged to form a new work titled SNOMED Clinical Terms (SNOMED CT). One of the first steps in this process was to create maps between semantically equivalent and proximate concepts in the two terminologies. Same-as and is-a relationships were used to map the descriptions from one terminology to concepts in the other terminology. The objectives were to identify semantically equivalent concepts in the two terminologies, to find the most semantically proximate is-a relationships for non-equivalent concepts, and to evaluate the synonymy in the source terminologies. The results suggest that the rate of semantic overlap between descriptions in SNOMED RT and CTV3 is approximately 28%. This article discusses the methodology, issues, and findings of the description mapping process.

Messages for communication of electronic health care records in diabetic care.

This paper summarises the current status of work to develop a European Standard message for communication information from Electronic Health Care Records. This is part of the current work programme of the Technical Committee of the European Standardization Committee concerned with Health Informatics. This Standardization process is aimed at providing a general solution to the requirements for electronic communication between a diversity of clinical information systems. However, the two priority areas chosen for initial validation are Primary Care and Diabetes Care. The second of these areas is being addressed in close liaison with a messaging sub-group of the Diabetes Optimization through Information Technology study group of the European Association for the Study of Diabetes. Good early progress has been made and the timetable for completion of this work is short. The project team hopes to complete their work by the end of 1998 and formal adoption as a European Standard is scheduled for mid 1999. At this stage suppliers of clinical information systems will be able to implement Standard messages to support the communication of Electronic Health Care Record information. Once the Standard has been widely implemented, diabetologists, general practitioners, other specialists and health professionals from other disciplines should be able to exchange clinical information in a safe and useful manner.

Interspecies transmission of influenza viruses: H5N1 virus and a Hong Kong SAR perspective.

This account takes stock of events and involvements, particularly on the avian side of the influenza H5N1 'bird flu' incident in Hong Kong SAR in 1997. It highlights the role of the chicken in the many live poultry markets as the source of the virus for humans. The slaughter of chicken and other poultry across the SAR seemingly averted an influenza pandemic. This perspective from Hong Kong SAR marks the coming-of-age of acceptance of the role of avian hosts as a source of pandemic human influenza viruses and offers the prospect of providing a good baseline for influenza pandemic preparedness in the future. Improved surveillance is the key. This is illustrated through the H9N2 virus which appears to have provided the 'replicating' genes for the H5N1 virus and which has since been isolated in the SAR from poultry, pigs and humans highlighting its propensity for interspecies transmission.

Validation of a European message standard for electronic health records.

A European Standard message for communication of the contents of Electronic Health Records is currently at a late stage in development and is due to be adopted during 1999. This paper reports on the development and content of this message and on current work to clinically validate this message. The validation process involves a new method based on an instantiation of the proposed message in the Extensible Mark-up Language. This method allows the message to be viewed and compared with the same record on the source system.

Characterization of avian H5N1 influenza viruses from poultry in Hong Kong.

The transmission of avian H5N1 influenza viruses to 18 humans in Hong Kong in 1997 with six deaths established that avian influenza viruses can transmit to and cause lethal infection in humans. This report characterizes the antigenic and biological properties of the H5N1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in Hong Kong during 1997 and compares them with those of virus isolated from the index human case. Each of the H5N1 viruses from Hong Kong poultry markets that were tested were lethal in chickens, possessed polybasic amino acids at the carboxy-terminus of HA1, and by definition were highly pathogenic in poultry. The available nonpathogenic H5 influenza viruses and the pathogenic H5N1 virus from Hong Kong were analyzed with monoclonal antibodies prepared to A/chicken/Pennsylvania/1370/83 (H5N2). The analysis revealed limited antigenic drift in 15 years and established that monoclonal antibodies are useful reagents for identification and antigenic analysis of avian strains that may transmit to humans in the future. One of the monoclonal antibodies permitted separation of the H5N1 influenza viruses from poultry into two groups that correlated with the presence or absence of a carbohydrate at residue 158 adjacent to the receptor binding site on HA. The H5N1 viruses examined replicated in geese, pigs, rats, and mice, but to only a very limited extent in ducks. It is noteworthy that all infected geese shed virus and that the H5N1 viruses caused disease signs and death in a portion (3 of 16) of the geese, with evidence of systemic spread to the brain. The tropism for geese is unusual and may provide insight into the origin of these viruses. In mice, the H5N1 virus caused lethal pneumonia and spread systemically to the brain. Mice would thus provide an ideal model system for studying immune responses and pathogenesis. Transmission experiments in chickens revealed that the H5N1 viruses are spread by fecal-oral transmission rather than by aerosol, and that the viruses are inactivated by drying of feces at ambient temperature. However, infectivity is maintained for at least 4 days in wet feces at 25 degreesC. There were differences in the morphology of the H5N1 viruses isolated from birds and humans. The perpetuation of H5N1 influenza viruses in the poultry markets in Hong Kong and the transmission of these viruses to humans emphasize the importance of these markets in the epidemiology of influenza. The poultry markets are of critical importance in the perpetuation and transmission of influenza viruses to other avian species and to mammals, including humans.

A proposed standard for registration of coding schemes.

This paper describes a proposed European standard for the Registration of Coding Schemes used in electronic healthcare information exchange. The requirements for such a standard are outlined together with the manner in which the work to meet these requirements has been carried out. The paper includes a summary of the main points contained in the proposed standard and in the supporting documents delivered by the project team. The paper concludes with a report on the progress of this proposal towards acceptance as a standard and a brief comment on how it may influence other work in medical informatics standardisation.

Possible waterborne transmission and maintenance of influenza viruses in domestic ducks.

Two duck farms in Hong Kong were examined monthly for 1 year for the occurrence and persistence of influenza viruses within the duck communities. The predominant virus in one community was H3N2, a virus antigenically related to the pandemic Hong Kong strain. This virus was isolated monthly throughout the year from feces or pond water or both, indicating a cycle of waterborne transmission. Viruses of the same antigenic combination were isolated 1 and 2 years after the last sampling occasion, implying persistence in the community. Infection was asymptomatic. Maintenance of virus appeared to be dependent upon the continual introduction of ducklings susceptible to infection onto virus-contaminated water; the feces of ducks 70 to 80 days old were generally free of detectable virus despite the exposure of the ducks to virus in pond water. In the second community, in which ducklings were not introduced after the initial sampling, the prevailing viruses, H7N1 and H7N2, also present asymptomatically, ceased to be detected once the ducks were 70 to 80 days old. The normal practice of raising ducks of different ages on the same farm, wherein the water supplies are shared, as typified by the first community, appears to be instrumental in maintaining a large reservoir of influenza viruses in the duck population of southern China.