Arthropod Vectors of Biological Agents and Their Control

Arthropod Vectors of Biological Agents and Their Control

Arthropod Vectors for Biological Weapons

Vector control in response to attacks with biological weapons.

Methods of Control - Short or Long Term

In the event of an attack with a vector-borne biological weapon, e.g. using a mosquito, a number of what may be seen as harsh short term measures may need to be taken to prevent the vector becoming established in the area and causing continuing problems. If the vector and disease should become established, which can be a risk if the vector is well matched to the area, then a number of long term measures, such as diverting or re-engineering the flow of rivers may become necessary. The emphasis here is on short-term responses.

Arthropod Vectors of Biological Agents and Their Control

Arthropod Vectors for Biological Weapons

Mosquitos (Culicidae)

Anopheline mosquitos

Culicine mosquitos

Horseflies (Tabanidae)

Fleas (Siphonaptera)

Lice (Anoplura)

Hard Ticks (Ixodidae)

Scrub typhus mites (Trombiculidae)

Vector control in response to attacks with biological weapons.

About half of all of the agents listed by the Australia group are dependent upon a vector to carry the disease to victims. These are almost always arthropods (insects and arachnids, including mites, ticks and fleas). In the event of such an attack, control of the vector is a key component to limiting its effects.

When an attack with a vector-dependent agent is suspected the vector must be rapidly identified to confirm the identity of the agent and to guide and monitor efforts at control. In particular, warning and informing the general public and getting their cooperation, e.g. in identifying possible vector habitats. and in accepting controversial actions such aerial spraying of insecticides will become immediately important.

Methods of Control - Short or Long Term

In the event of an attack with a vector-borne biological weapon, e.g. using a mosquito, a number of what may be seen as harsh short term measures may need to be taken to prevent the vector becoming established in the area and causing continuing problems. If the vector and disease should become established, which can be a risk if the vector is well matched to the area, then a number of long term measures, such as diverting or re-engineering the flow of rivers may become necessary. The emphasis here is on short-term responses.

Consider the following questions.

When does the vector feed?

Does it feed:

At dawn (crepuscular feeding)?

During the day?

At evening twilight?

At night?

Where does it feed?

Indoors?

Outdoors?

Where does it rest when not feeding?

In buildings?

In open areas?

Where does it lay its eggs?

In clean, fresh water?

In fresh water contaminated with organic waste?

In brackish water?

In damp areas?

How often does the vector take a blood meal?

How long is the life cycle?

What other diseases might the vector carry?

What other organisms might the vector feed on to create reservoirs of the agent?

What sort of agents will kill the vector?

What sort of repellents can be used?

What sort of behavioral changes will protect people?

Once the vector is identified, many of these questions can be answered and appropriate actions can be taken. For example, treatment of standing water is important in mosquito control, but not in the control of horseflies. Indoor fogging may be effective against some species but not others. Some vectors will bite light-skinned people through dark clothing, but not through light clothing.

Some of these identifications are actually very difficult and the technicalities of sampling and identification will no be discussed here. It is more important to ensure that public health entomologists are aware of the problem and that they are familiar with the necessary identification procedures and are ready to become involved in responding to an attack.