Detecting the known- latest technologies in pen-side tests…a reliable test even when it is raining and dark?

Kath Webster & Andrew Soldan

Constraints- Resource poor?• Not much money

– Low input systems eg sheep in Australia or poultry in Malawi• No/poor facilities

– Heat, light, power, shelter• Little expertise

– Laboratory tech, service engineers, result interpretation skills• Poor supply/communication lines

– Cold chain + storage, no transport, result communication • Inability to take sample

– Blood, faeces, • Very little time

– Other work to do – stopping to run a test does not fit into work flow

Other drivers to move test from the lab

• No existing test• Human safety• Better customer service• Lower overall cost• Need for rapid results• Sample deterioration

Personal case studies

Sheep with mouth lesions during FMD outbreak in UK 2001

• Flock of 30 – not quite pets but close!

• Lesions in mouth of three• Two miles from infected

farm but not contiguous• FMD could not be ruled out• Slaughtered• Compensation ~US$2,000

Dog with starey eyes in Chitipa Northern Malawi

• One person bitten• Whole village concerned• Post exposure treatment second

biggest drug cost to Malawi health system after malaria treatment

• No holding facilities• 8 hrs drive to central lab

Horse with nasal discharge in Devon, UK

• DIY livery yard with ~30 horses

• New horse with runny nose• Differential – Strangles (S

equi equi)• Other owners saying horse

should be moved out of yard• Swab taken, horse isolated

and result in 48hrs

What is an ideal test for such situations

• Cheap- <$1 to $20 for test. No equipment or very cheap equipment - <$500?

• Robust in range of situations, ideally does not need external power source

• Easy to use - 10 min familiarisation with the instructions, result interpretation easy

• Little/no sample prep, droppers not pipettes• Temperature stable in storage• Rapid result - <30 min• Accurate enough to inform a decision

Yes• Rose Bengal Plate test• Latex agglutination tests• Lateral flow devices• SNAP tests• Urine dip sticks• Glucometer

Do such tests exist?

Pregnancy test

• Gold standard for point of care testing• Untrained user• Rapid – 1 to 3 minutes• >99% accurate 2w after conception• Informative• Cheap ~ $4 each

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Some interesting technologies

• More of what we have already – LFD, SNAP etc• Miniaturised/simplified PCR based• Array based• Isothermal amplification based• Paper based• Biological sensor based• Sequencing

Miniaturised/simplified PCR based

Miniaturised/simplified PCR based

Array based

Isothermal amplification based

Isothermal amplification based

Isothermal amplification based

Paper based

Biological sensor based

Sequencing

Technology is great but ………

• Is it cheap enough? – both instrument and test cost

• Does the operator have the right skills?– To select test– To do test– To take sample– To interpret result

• Is it robust enough?• Is it accurate enough?

Where will the test be done?

• Pen side• In the kitchen/farm office• At a forward operating base in an outbreak• In a laboratory

– Regional lab– Local lab– Central lab

Conclusions

• Confusion between the need for rapid results and the need for on farm testing – technical solutions may be different

• Technology is advancing rapidly• New tests will appear • Molecular – no/little equipment costs• These tests will require little training to use• There will be a move from central labs to local labs –

Abattoir, LDCCs, practice labs, private labs etc• Advantages for the developing worldThe major move is going to be from central lab to local lab – not onto farm