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WHO Report on Health Aspects of Biological
and Chemical Weapons

16 October 2001

Dear Doctor,

Public health surveillance is the cornerstone to monitor diseases and injuries that affect the health of the population. Prompt recognition of unusual disease trends and patterns, whether natural or man-made, is vital to contain an outbreak and its source. This same principle applies to diseases caused by biological weapons. Here, indeed, the role of the alert clinician is paramount, because he/she may be the first person to pick up unusual signs of diseases and act as the trigger for further action.

In this connection, the World Health Organization (WHO) has recently published via its homepage (This link will open in a new window a 179-page draft projected second edition of Health Aspects of Chemical and Biological Weapons : Report of a WHO Group of Consultants, Geneva : WHO (1970). The main purpose of the Report is to provide technical support to the international community for developing or strengthening preparedness and response activities against risks posed by biological and chemical agents, as an integral part of their emergency management programmes. Some parts of the Report on biological weapons are highlighted below for your easy reference.

  Biological Weapons

In order to be effective as a weapon, an agent needs to be highly infective, be stable enough to resist degradation during handling and storage, and be spread in a such way that the necessary infective dosage is delivered to the target population.

Biological agents may be bacteria, rickettsiae, chlamydia, viruses or toxins. While thousands of pathogenic microorganisms have been investigated for their potential utility as weapons, only some forty biological agents have been identified as satisfactory candidates, for examples, Bacillus anthracis (anthrax), Yersinia pestis (plague), Variola major (smallpox), Brucella species (brucellosis) and Salmonella typhi (typhoid fever).

Biological agents can be characterized by their intrinsic features, notably infectivity, virulence, lethality, pathogenicity, incubation period, mode of transmission and stability, all of which influence their potential for use as weapons.

The most immediate consequence of incidents involving biological weapons is their ability to cause mass casualties and their potential for overwhelming medical resources and infrastructure secondary to psychological reaction of the population to the attack. They may also have the potential for causing physical or mental illnesses months or years after the attack.

Public Health Preparedness and Response

The first indication of an incident could be a warning, or the finding of an unusual device or unusual materials. One or more of the following activities may be required :

  • analysis of available information
  • initiation of a search procedure for a suspect device or location
  • establishment of a cordon
  • hazard reduction and/or neutralization
  • early identification of a nature of the hazard, whether it is biological, chemical or mixed

Generally speaking, a biological agent attack would have the characteristics of a disease outbreak. Establishing routine sensitive and near real time disease surveillance systems will serve a dual purpose in natural and deliberate outbreaks.

Response to an established biological attack is a multidisciplinary and complex task, which will require co-operation between civil defence, emergency response, law enforcement, public health and medical personnel. The requisite response activities can be identified through the principles of risk management.

  1. Identify the hazards
    Identify the nature of agent involved; define the population at risk and develop an initial hypothesis on the source of the agent and mode of transmission.

  2. Evaluate the hazards to determine initial risk
    Evaluate potential outbreak spread, and assess current and delayed case management requirements.

  3. Introduce risk reduction strategies
    Implement a risk communication programme for the affected population that conveys information and instructions as needed; order necessary supplies and organize needed personnel; protect responders and healthcare workers; introduce infection prevention and control procedures and ensure medical care of infected cases.

  4. Quantify the residual risk, and make a risk acceptance decision
    Decide whether local resources are adequate and whether international resources should be accessed.

  5. Monitor the risk management programme, and repeat the process as
    Implement active surveillance to monitor the effectiveness of prevention and control procedures and follow up activities.

As you can see from the WHO Report, proper surveillance and quick coordinated response are vital to protect the public from the deliberate use of biological agents.

Hong Kong has a well-established disease surveillance system involving healthcare providers in both the public and private sectors. This disease surveillance system forms an integral part of the Hong Kong Government's Comprehensive Contingency Plan to deal with attacks involving biological and chemical agents. It is important to note that the risk of Hong Kong as a target for biological and chemical attacks is very low. This notwithstanding, the Hong Kong Government has already stepped up security measures and vigilance in our preparation for countering possible incidents, whether accidental or intentional.

The Department of Health (DH) stands ready to offer advice and assistance to medical professionals who detect unusual or unexplained pattern of illnesses. Please notify the DH Headquarters at 9031 6925 or 9031 8675 of such incidents.

Yours sincerely,

(Dr. L.Y.Tse)
for Director of Health
  Last Revision Date : 11 Jan 2013