Challenges to Global Surveillance and Response to Infectious Disease Outbreaks of International Importance

Notional Scheme of Global Surveillance and Response

Figure 1. Some of the factors that affect the flow of information in the scheme are detailed in the footnotes to the figure.22

Once infected, onset of illness may be fast or slow. Self-recognition of illness depends on the severity of signs and symptoms; these can range from unnoticeable to mild, moderate, or severe.
If a person recognizes he or she is sick, he or she may or may not seek health care.
If a sick person seeks health care, the healthcare provider may diagnose a common or an unusual disease.
Some reasons for not seeking care include: health care is unavailable; health care is unaffordable; the healthcare system is not trusted; illness may be very mild; the disease is stigmatized; severe illness prevents healthcare seeking.
A disease outbreak may be detected by other societal elements, such as schools (increases in absenteeism), first responders (increases in emergency rescues), or pharmacies/traditional healers (increases in medicine sales).
If an unusual case of disease is recognized, particularly if it meets the case definition (e.g., watery diarrhea) for diseases of concern (cholera), one or more notification processes may begin. The healthcare provider may informally discuss the case with other clinicians; hospital infection control may be notified; the ministry of health may be notified.
An unusual cluster of disease cases is an outbreak of a “common disease or syndrome” that is unusual with respect to season, location, demographics, or morbidity/mortality. For example, based on historical analyses of influenza pandemics, abnormal clusters of disease may be the first warning of the emergence of a strain with pandemic potential. Possible signals include an early or an extended flu season, severe illness in younger people, increased mortality, or changes in mortality patterns (i.e., seasonal or demographics of fatal cases). Recognition of such trends is difficult without making comparisons with historical population-based data.
If available, a diagnostic test may be ordered. To be useful in the primary or emergency care facility, such diagnostic tests must be simple and affordable without sacrificing accuracy. When performed on patients who have signs and symptoms of disease, the results of the test must provide actionable information for care of the patient, for infection control in the healthcare facility, for outbreak reporting, for investigation, and for rapid containment.
The diagnostic test results may reveal an unusual disease. If the patient was not hospitalized, it may be difficult to relocate him and provide appropriate treatment and/or vaccination.
If the laboratory test confirms the sick person has a disease that is vaccine preventable (e.g., polio), screening for asymptomatic carriers and vaccination campaigns may be initiated.
The news media may report disease outbreaks from a variety of information sources, including societal sources, healthcare providers, or other people who work in hospitals, health departments, or other government departments.
Concerns about the impact of the disease outbreak on international trade and travel responses may dissuade countries from reporting the disease outbreak or requesting assistance. Such delays affect the size of the outbreak in the country as well as regional or international spread of the disease.23
Member States of the World Health Assembly that have agreed to IHR 2005 are responsible for reporting outbreaks of seven diseases, as well as any unusual disease outbreaks and unusual clusters of disease cases with potential for international public health impact, to the World Health Organization within 24 hours, regardless of the location of the outbreak.
WHO staff reviews disease outbreak reports daily; several questions are considered before WHO takes action on the report:
• Is the disease one of seven that is reportable (smallpox, plague, yellow fever, cholera, polio, SARS, or influenza caused by a new strain of human virus)?
• Is it an unknown disease?
• Is there potential for spread beyond national borders?
• Is there a serious health impact or unexpectedly high rates of illness or death?
• Is there potential for interference with international trade or travel?
• Does the country have the capacity to contain the outbreak?
• Is the outbreak suspected of being caused by a laboratory accident, or a deliberate act?6
If the report seems credible and the outbreak could potentially be a threat of international public health significance, a request for verification is relayed to the appropriate WHO regional office and the involved country is asked to investigate the outbreak report.6
WHO offers assistance to the country for the investigation of the reported disease outbreak. Assistance includes, but is not limited to, information, diagnostic tests, and field staff. In most cases, the involved country must request the assistance. The type and amount of assistance reflect the disease, the size of the outbreak, and the national resources of involved countries.24
If the outbreak is verified, WHO will provide additional resources, such as therapeutics and vaccines; maintain situational awareness; and coordinate any and all aspects of the response, including the involvement of WHO’s Global Outbreak Alert and Response Network (GOARN).24
GOARN is a voluntary technical partnership of approximately 140 institutions coordinated by WHO to support countries in disease outbreak response, primarily through the deployment of multidisciplinary teams of experts.25
The response to the outbreak will occur on multiple levels within the involved country. If the outbreak has spread beyond the borders of the involved country, responses of countries in the region and/or the international community may occur simultaneously.
All funds required for international response to disease outbreaks are donated at the discretion of World Health Assembly Member States.