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Chapter 11 of 16

Infectious diseases are the biggest killer of the young

• Epidemics of unidentified and re-emerging diseases have underlined the need for global surveillance systems
• National reporting systems need strengthening. A new approach is being pioneered in Africa
• FluNet, RABNET and other global alert systems
  

• Pneumonic plague in India • HIV/AIDS • Bird influenza in Hong Kong SAR•
Meningitis monitoring in Africa • Cholera in Peru

Graphs & Maps:

• Unexpected outbreaks(Map)
• Reported outbreaks of infectious diseases 1998-1999
• Newly identified infectious diseases and pathogens

Initiative: First line defence against flu

The appearance of pneumonic plague in Surat in India in 1994 led thousands to flee to other areas - at the risk of spreading the epidemic elsewhere. The outbreak highlighted the need for good disease intelligence systems. Early identification of the cause followed by a rapid response can prevent a small outbreak from becoming a major epidemic.

During 1997, the vast majority of countries had at least one infectious disease outbreak. Several had as many as eight. Some of the diseases involved - cholera, plague, typhoid, and meningitis - were old foes. Others - like the new variant Creutzfeldt-Jakob disease, a bird influenza affecting humans for the first time and a virus carried by pigs - were less familiar.

If a global disease surveillance system had not been in place the outcome could have been disastrous. Ultimately national surveillance systems need to be strong enough, not only to provide constant alert and rapid response to outbreaks of endemic diseases, but also ready to respond to a sudden unexpected outbreak of a known or unknown disease. The emergence of the HIV/AIDS pandemic in the 1980s is a devastating example of what can happen when the world is looking the other way.

Reporting systems are the intelligence network that underpins disease control and prevention. Without this framework in place it is impossible to track where disease is occurring, measure progress in disease control targets, monitor antimicrobial drug resistance, or provide an early warning system for outbreaks and the emergence of new diseases. Surveillance data is also needed to assess where resources should go for maximum cost-effectiveness.

Today, efforts are under way to strengthen national surveillance systems through epidemiology and laboratory training, and to help countries establish integrated surveillance systems. The aim is to improve surveillance capacity through streamlining activities and establishing good reporting systems in which information is shared - and used - at the national, regional and global levels. This reinforced approach is being pioneered in Africa.

At a global level, WHO has established an epidemic intelligence team who monitor and verify reports of outbreaks anywhere in the world and provide a response team, where needed. WHO has also developed a global alert system which prioritizes surveillance for diseases such as influenza (FluNet), rabies (RABNET), HIV/AIDS, Creutzfeldt-Jakob disease and related diseases.

In 1997, FluNet picked up reports of a new form of human influenza transmitted from birds. This virus had killed a three-year-old boy in Hong Kong SAR. The incident sparked off fears of a new pandemic which - unless contained - could spread to other continents and kill millions. In the 1918 influenza pandemic 20-40 million people died in one year - more than the total deaths during the First World War. It could happen again.

Six months later another outbreak caused 17 cases and five deaths. Through a rapid outbreak response - which sampled over 1 800 animals and birds - the virus was traced to live poultry. The authorities responded by establishing an intensified surveillance network and by destroying all live poultry stocks. By the end of 1997, only 18 cases had been confirmed. The virus did not appear to have been transmitted person-to-person and the threat of a pandemic receded. In 1999, the new system detected and reacted to yet another new type of animal influenza in humans.

Every year FluNet gathers surveillance data from around the world on the various strains of flu virus that affect humans. Twice a year, recommendations are made to manufacturers on the content of the next year's influenza vaccine so that effective vaccines are available each year.

In 1996, Africa experienced the world's largest recorded epidemic of meningitis involving over 187 000 cases and 20 000 deaths. At the time, vaccine stocks were exhausted and countries were late in recognizing the outbreak. To make matters worse, the wealthier countries started buying up vaccine - in excess of real needs. Countries with vaccine stocks were using it sometimes in an unplanned way and with unsafe injection equipment.

In response WHO established an interagency group to monitor the incidence of meningitis and coordinate the emergency supply and fair distribution of meningitis vaccine for countries in greatest need and ensure that it was used safely. The group estimates vaccine needs, and oversees the purchase and distribution of an emergency stock of high-quality vaccine and injection equipment. Countries get rapid access to the emergency stock of vaccine at a preferential price.

Early warning systems and prompt intervention to contain an outbreak can be highly cost-effective as well as saving lives. In Peru, an epidemic of cholera in 1991 cost an estimated $770 million in lost trade and tourism - almost one-fifth of normal export earnings. Three years later the epidemic of plague in India resulted in losses totalling $1.7 billion. Hotel bookings fell by 20%-60% and one airline lost $1 million a week. Elsewhere, the mass slaughter and destruction of cattle, pigs and poultry in the United Kingdom, Malaysia and Hong Kong SAR respectively, have caused heavy economic losses.