Biosafety training course for Africa related to genetically modified disease vectors

Containment issues during planned field cage trials




Phased testing

  1. Laboratory studies.
  2. Analytic or computer simulation studies.
  3. Contained field trials.
  4. Open release trials.


Phased testing

Figure 1: Flow chart describing the phased testing of GM mosquitoes. Column A shows the testing phase, column B shows the steps required for research and development, and Column C shows the field site development pathway.


1. Laboratory studies

Evaluate basic characteristics of GM mosquitoes:

Does the anti-pathogen gene work?

Does the gene drive system work?

Test for unintentional adverse effects of transgenic DNA:


2. Analytic or computer simulation studies

Incorporate information from all biological studies:

Results can contribute to:


3. Contained field trials


Field Cage

Figure 2: A mosquito containment facility at the Ifakara Health Research and Development Center in Tanzania.


Requirements before beginning contained field trials:

Phases of contained field trials:

Before conducting the trial:

Conducting the trial:


4. Open release trials

Phases of open release trials:


Containment methods

Physical containment:

Biological containment:

Ecological containment:


Breaches of containment


Possible breaches of containment: How they can be avoided:

Structural failure of the cage due to:

  • Predictable environmental damage (e.g. wind, rain, UV exposure)
  • Unpredictable environmental damage (e.g. tornados, earthquakes, lightning)
  • Human damage (e.g. vehicles)
  • Animal damage

  • Design cage to withhold weather and environmental damage.
  • Plan experiments for more environmentally stable times of the year (e.g. not during monsoon season).
  • Restrict vehicle and parking access around the facility.
  • Plan routine examination of cage integrity.

Accidental release due to:

  • Unavoidable accident (e.g. water leak containing eggs, larvae, pupae)
  • Preventable accident (e.g. leaving door open due to human error)
  • Unapproved change or conscious relaxation of biosecurity protocol
  • Inadequate training of personnel.

  • Placement of cage to minimize possibility of accidents.
  • Write clear and explicit protocols in the languages of all employees.
  • Develop safety courses and rehearse procedures regularly.

Deliberate actions leading to a breach:

  • Vandalism.
  • Sabotage.
  • Burglary.

  • Establish good community relations, education and outreach.
  • Take local ethical, social and cultural issues into account during site selection.
  • Maintain an ongoing commitment before, during and after the trial.
  • Install physical barriers and security systems at the site.
  • Perform background checks on all potential employees.

Caged GM mosquitoes could mate with wild local mosquitoes through the cage mesh walls.

  • Design a cage having two walls of screening.

Possible interactions between caged mosquitoes and non-target organisms:

  • Exposure of GM mosquitoes to microbes and nematodes resident in soil or on plants within the cage.
  • Entry of small invertebrate organisms from the wild into the cage through cracks, mesh or drains.
  • Transfer of organisms into the cage by employees via clothing, footwear, tools or equipment.
  • Exposure of organisms brought into the cage as a source of bloodmeal to transgenic material.

  • Design transgenic DNA to be non-functional in non-target organisms.
  • Design containment facility to prevent entry and exit of small organisms.
  • Decontaminate soil, plants, animals and employee clothing before removing them from the cage.
  • Prevent interactions between mosquitoes and employees within the cage.
  • Treat drainage water from the cage.

Table 1: Possible breaches of containment from field cages and how they can be avoided.


Recommendations for trial conduct

Choice of location:

Design choices:


Containment room

Figure 3: A containment room for entry into individual cages designed to enhance protection against escape.



Prevention of inadvertent release:

Remediation of inadvertent release: