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Disease surveillance

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Reporting disease cases refers to modern international human infectious disease surveillance. Surveillance of the causative agents of human diseases can include surveillance of that agent in nonhumans.

In modern times, reporting incidences of disease outbreaks has been transformed from manual record keeping to instant world wide internet communication.

The number of cases could be gathered from hospitals - who could be expected to see most of the occurrences - collated, and eventually made public. With the advent of modern communication technology, this has changed dramatically. Organizations like the World Health Organization and the Centers for Disease Control now can report cases and deaths from significant diseases within days - sometimes within hours - of the occurrence. Further, there is considerable public pressure to make this information available quickly and accurately.

Mandatory reporting

Infectious diseases reporting is a requirement placed upon health care providers by many regional and national governments, and upon national governments by the World Health Organization (WHO). Since 1969, WHO has required that all cases of six diseases, cholera, plague, yellow fever, smallpox, relapsing fever and typhus, be reported to it. In 2005, the list was extended to include polio and SARS. Regional and national governments typically monitor a larger set of (around 80 in the U.S.) communicable diseases that can potentially threaten the general population. Tuberculosis, HIV, botulism, hantavirus, and anthrax are examples of such diseases.[citation needed]

World Health Organisation

The World Health Organisation is the lead agency for coordinating global response to major diseases. The WHO maintains Web sites for a number of diseases, and has active teams in many countries where these diseases occur.

During the SARS outbreak in early 2004, for example, the Beijing staff of the WHO produced updates every few days for the duration of the outbreak.[1] Beginning in January, 2004, the WHO has produced similar updates for H5N1.[2] These results are widely reported and closely watched.

WHO's Epidemic and Pandemic Alert and Response (EPR) to detect, verify rapidly and respond appropriately to epidemic-prone and emerging disease threats covers the following diseases:[3]

Political challenges

As the lead organization in global public health, the WHO occupies a delicate role in global politics. It must maintain good relationships with each of the many countries in which it is active. As a result, it may only report results within a particular country with the agreement of the country's government. Because some governments regard the release of any information on disease outbreaks as a state secret, this can place the WHO in a difficult position.

The WHO coordinated International Outbreak Alert and Response is designed to ensure "outbreaks of potential international importance are rapidly verified and information is quickly shared within the Network" but not necessarily by the public; integrate and coordinate "activities to support national efforts" rather than challenge national authority within that nation in order to "respect the independence and objectivity of all partners". The commitment that "All Network responses will proceed with full respect for ethical standards, human rights, national and local laws, cultural sensitivities and tradition" ensures each nation that its security, financial, and other interests will be given full weight.[4]

Technical challenges

Testing for a disease can be expensive, and distinguishing between two diseases can be prohibitively difficult in many countries. One standard means of determining if a person has had a particular disease is to test for the presence of antibodies that are particular to this disease. In the case of H5N1, for example, there in a low pathogenic H5N1 strain in wild birds in North America that a human could conceivably have antibodies against. It would be extremely difficult to distinguish between antibodies produced by this strain, and antibodies produced by Asian lineage HPAI A(H5N1). Similar difficulties are common, and make it difficult to determine how widely a disease may have spread.

There is currently little available data on the spread of H5N1 in wild birds in Africa and Asia. Without such data, predicting how the disease might spread in the future is difficult. Information that scientists and decision makers need to make useful medical products and informed decisions for health care, but currently lack include:

  • Surveillance of wild bird populations
  • Cell cultures of particular strains of diseases

H5N1

H5N1

Surveillance of H5N1 in humans, poultry, wild birds, cats and other animals remains very weak in many parts of Asia and Africa. Much remains unknown about the exact extent of its spread.

H5N1 in China is less than fully reported. Blogs have described many discrepancies between official China government announcements concerning H5N1 and what people in China see with their own eyes. Many reports of total H5N1 cases have excluded China due to widespread disbelief in China's official numbers.[5]

"Only half the world's human bird flu cases are being reported to the World Health Organization within two weeks of being detected, a response time that must be improved to avert a pandemic, a senior WHO official said Saturday. Dr. Shigeru Omi, WHO's regional director for the Western Pacific, said it is estimated that countries would have only two to three weeks to stamp out, or at least slow, a pandemic flu strain after it began spreading in humans."[6]

Dr. David Nabarro, chief avian flu coordinator for the United Nations, says avian flu has too many unanswered questions:

  • No one knows how many could die.
  • No one knows how far it has spread. In Africa "surveillance is so poor that deaths of chickens or humans could easily go undiagnosed for weeks."
  • No one knows much about future pandemic mutations, except they are increasingly likely due to millions more birds in many more countries leading "to an exponential increase of the load of virus in the world [...] Each infected bird and person is actually awash in minutely different strains, and it takes lengthy genetic testing to sequence each one - so if a pandemic strain were to appear it might be quite difficult for us to pick up that change when it happens."
  • No one knows why "the disease, after years of smoldering in poultry, suddenly start hitchhiking in migratory birds."
  • No one knows why "the northern China strain - the one now spreading westward - cause[s] so many false negatives in diagnostic tests".
  • No one knows why so many people fell sick so quickly in Turkey.
  • No one knows the significance of H5N1 spread by mammals such as cats.
  • No one knows enough about what virus strains are in which bird species to make useful predictions.
  • No one knows enough about bird migration patterns to make useful predictions. Bird species' migration strategies can vary according to age, sex, weather and season, among other things.
  • No one knows how lethal the next influenza pandemic will be.
  • No one knows when it will occur.
  • No one knows if any of the prepandemic vaccines now being tested will have been of any use when the pandemic happens.
  • No one knows if any of the nonvaccine drugs will be of any use against the pandemic virus when it comes.
  • No one knows if H5N1 will ever go away.[7][8]

"The Scientific Seminar on Avian Influenza, the Environment and Migratory Birds met from 10-11 April 2006 at UN Office in Nairobi, Kenya. The Seminar was organized by the United Nations Environment Programme (UNEP) Division of Early Warning and Assessment (DEWA) in cooperation with the Convention on Migratory Species of Wild Animals (CMS) and its Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). [...] Hepworth identified the Seminar’s objectives to: stimulate debate on the role of wild birds in transmitting the virus; provide up-to-date status reports and advice for decision-makers; increase awareness of the recent multilateral environmental agreement (MEA) resolutions among all governments; promote further research on virus behavior and transmission; and encourage international technical cooperation and risk mitigation." The seminar concluded with reaffirmations to disseminate the Seminar’s findings and to manage the risks associated with HPAI. The seminar examined surveillance issues: "Ward Hagemeijer, Wetlands International, presented options for an early warning system for HPAI in wild birds. He stated that an early warning system should function as a strategic tool to avoid dramatic impacts and elaborated on different components of early warning, including sampling. He said the cost implications of sampling are high in situations where prevalence is low, highlighting that only six out of 13,000 birds tested positive for the virus in China. He underscored the importance of establishing baseline data and the possibility of using sentinel birds – virus-negative birds that are closely monitored – to ascertain the prevalence of the virus. [...] Addressing FAO’s activities on wild bird surveillance in Africa, Vincent Martin, FAO, said that FAO, with support from other partners, initiated five regional technical cooperation programmes (TCPs) in November 2005 as a proactive response to HPAI. He noted that these programmes aim to enhance local knowledge and capacity with regard to epidemiology, wildlife surveillance and laboratory diagnostics. Martin discussed the West African TCP, which focuses on the Senegal, Niger and Chad River basins for active surveillance using a quick risk assessment process. He noted that as these river basins are significant wetlands with large congregations of wild birds in proximity to poultry, they are potential sites for the introduction of the H5N1 virus into West Africa. Observing that H5N1 was not detected in 3500 samples taken in Chad, Mali, Ethiopia and Morocco, Martin highlighted the constraints of wild bird surveillance noting that it is resource intensive. He called for training in capture and sampling techniques in addition to collaboration within different government departments. Martin emphasized the need to analyze surveillance results, review surveillance protocols and enhance understanding of migratory patterns within Africa, including through ringing and examining wetlands dynamics as environmental triggers for migration. Ahmed Djoghlaf, CBD Executive Secretary, presented the outcomes of the CBD brainstorming meeting on HPAI held prior to the eighth Conference of the Parties (COP-8) to CBD in March 2006, and the resulting COP-8 Decision on Avian Flu (UNEP/CBD/COP/8/L.35). He addressed the impact of HPAI on wildlife and lamented the lack of knowledge on the issues, particularly in Africa. [...] Christianne Bruschke, OIE, reaffirmed that HPAI is only a “notifiable disease” in poultry, not in wildlife. Noting factors that prevent some countries from fulfilling their notification requirements, she elaborated on a joint mechanism with FAO to pool all reported information and input from rapid assessment teams to inform other countries about the risk of contracting HPAI. [...] In a section on surveillance, early warning and risk assessments, participants state that early detection is essential for the control or eradication of HPAI, subtype H5N1. They note the considerable efforts of FAO, WHO and OIE to develop an integrated early warning system and underline the need to build upon existing initiatives. They stress the importance of ensuring adequate surveillance and rapid reporting and data-sharing systems, and specify that surveillance programmes should: be web-based; facilitate integrated responses and risk management; report associated meta-data that allow full analysis of the results; and facilitate timely and effective risk management."[8]

CIDRAP reported on August 25,2006 on a new US government Web site that allows the public to view current information about testing of wild birds for H5N1 avian influenza which is part of a national wild-bird surveillance plan that "includes five strategies for early detection of highly pathogenic avian influenza. Sample numbers from three of these will be available on HEDDS: live wild birds, subsistence hunter-killed birds, and investigations of sick and dead wild birds. The other two strategies involve domestic bird testing and environmental sampling of water and wild-bird droppings. [...] A map on the new USGS site shows that 9,327 birds from Alaska have been tested so far this year, with only a few from most other states. Last year officials tested just 721 birds from Alaska and none from most other states, another map shows. The goal of the surveillance program for 2006 is to collect 75,000 to 100,000 samples from wild birds and 50,000 environmental samples, officials have said."[9]

See also

Further reading

Sources and notes

  1. ^ WHO SARS
  2. ^ WHO H5N1
  3. ^ WHO EPR
  4. ^ WHO Outbreak Network
  5. ^ WHO WHO WHO WHO
  6. ^ ABC News from AP published May 7, 2006
  7. ^ NYT article picked up by IHT
  8. ^ a b International Institute for Sustainable Development (IISD) SCIENTIFIC SEMINAR ON AVIAN INFLUENZA, THE ENVIRONMENT AND MIGRATORY BIRDS ON 10-11 APRIL 2006 published 14 April 2006.
  9. ^ CIDRAP News article New Web tool tracks H5N1 testing of US wild birds published August 25, 2006
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