From AIDS to SARS to malaria and polio, infectious diseases are the scourge of people around the world. They sicken and kill millions, but their impact would be much greater if there was no coordinated global response. For that, the World Health Organization (WHO) and it's extensive network of agencies monitor disease hot spots, and respond to areas where there are outbreaks in an effort to contain them and save lives.
Global surveillance of infectious diseases is the main job of the World Health Organization which keeps its eye on outbreaks that could quickly become aggressive and spread to other countries.
Sometimes, people are stricken by local or regional outbreaks that flare up suddenly, such as cholera, polio, and Ebola. Other times, they fall ill to life-threatening illnesses no one has ever seen before, such as severe acute respiratory syndrome, or SARS, that threaten to become global pandemics.
SARS started in southern China in late 2002 and spread around the world, infecting 8,000 people and killing nearly 800 before it was brought under control. Most of the deaths occurred in China, Vietnam, and Singapore.
The WHO's Department of Communicable Disease Surveillance and Response keeps a close eye on such outbreaks. According to this WHO promotional video, the organization is alerted to potential epidemics by six regional offices and 141 country and liaison offices.
VIDEO: "Working with WHO staff worldwide, this network mobilized hundreds of others throughout the world; each playing an important role in this global effort. Epidemiologists, clinicians, laboratory scientists, environmental investigators, veterinarians, logisticians, communications experts, health care workers. They were all put through a hard test when SARS first struck. Questions had no answers. What is this? Where did it come from? How do we stop it? What is going on?"
The backbone of the World Health Organization's global surveillance and response effort is an early warning system called the Global Health Intelligence Network (GPHIN).
Developed by the Canadian government, GPHIN analysts monitor media reports of possible disease outbreaks, including potential biological weapons attacks by terrorists, 24 hours per day, seven days per week in seven languages.
Dr. Stephen Corber is with the Pan-American Health Organization of WHO.
"Traditionally, surveillance and reporting systems were set up so that local physicians or local laboratories notified local governments of confirmed cases of infectious disease," explained Mr. Corber. "This information was then passed to the provincial or state level, then to the national level, and eventually usually taking weeks or even months, internationally. GPHIN, on the other hand, gathers electronic media reports that have possible relevance to public health, and then makes these available around the world in a structured way, in a user friendly platform, all in near real time. After further assessment of the situation, a response to an outbreak may occur much sooner."
GPHIN officials say the system picks up some 20,000 reports per month of potential infectious disease outbreaks.
Public health analysts in Canada then sift through the information electronically and decide whether the reports are new information, or are of potential significance.
Mr. Corber says about half of the leads are discarded because they do not meet accepted criteria. He says those remaining are forwarded to the WHO for further screening.
"Everyday, we review this information, looking for such things as the extent of mortality, the need for assistance, the potential for containment, the risk to international spread," added Mr. Corber. "So, the things like that. Those things that pass through that screen are then evaluated by a senior team, and then a decision is made."
The process results in four to five serious leads per week.
In October 2004, reports started coming in of people dying of a mysterious illness in Uige province in Northern Angola. The disease was quickly identified as Marburg hemorrhagic fever, a lethal illness related to Ebola that is spread through contact with the body fluid of sick individuals.
There had been a less severe Marburg outbreak in neighboring Congo between 1998 and 2000 that killed 128 people.
Once the outbreak was confirmed, the World Health Organization mobilized international partners. Among the agencies that sent responders to Angola was the U.S. Centers for Disease Control (CDC) in Atlanta. The CDC's Epidemic intelligence officer, Boris Pavlin, says he managed field data.
"And then the other big thing that I was doing was field investigation of cases, which is sort of more what the movie-like portrayal is; riding out in jeeps to remote villages, and donning full protective suits to enter houses and evaluate patients that were, in most cases, already dead and take samples, in this cases, oral swabs of their cheek, to take back to the lab," said Mr. Pavlin.
A genetics lab set up by the Canadians could tell responders in about four hours whether someone had died of Marburg.
Mr. Pavlin says he had a visa to go to Congo to investigate any reports of outbreaks there, but responders were able to contain the disease in Angola.
There have been at least 323 deaths from Marburg hemorrhagic fever in Angola in an outbreak that is seen as largely over. But as is the case with hundreds of infectious diseases detected daily, it takes a highly motivated global surveillance and response effort to keep them in check.