Table of contents
- Introduction
- Parasite species
- Types and number of trials
- Timing of trials
- Adequacy of infestation
- Rainfastness
- Wool or hide damage
- Preamble for Appendix A of the WAAVP guideline: ticks on ruminants
- Preamble for Appendix C of the WAAVP guideline: myiasis-causing parasites on ruminants
- Preamble for Appendix D of the WAAVP guideline: lice and sheep keds on ruminants
1. Introduction
The World Association for the Advancement of Veterinary Parasitology (WAAVP) is a not-for-profit organisation for scientists who study the parasites of non-human animals. The guidelines, developed by the international expert working groups of the WAAVP, assist in the international harmonisation of standards and procedures for the evaluation of veterinary parasiticides. The WAAVP guidelines for evaluating the efficacy of ectoparasiticides on ruminants aim to standardise the minimum set of data that should be submitted to demonstrate the efficacy of new ectoparasiticides for use on or in ruminants.
The Australian Pesticides and Veterinary Medicines Authority (APVMA) has adopted the WAAVP guidelines for evaluating the efficacy of ectoparasiticides on ruminants to assist registration holders in the conduct of regulatory trials. The APVMA notes that in some instances the WAAVP guidelines advise consultation with the regulator. We also recognise that because of Australia’s unique environmental and geographic parameters, parasite burdens and their population dynamics, farm management practices and animal breeds, there are some differences between the WAAVP guidelines and the APVMA’s recommendations for efficacy trials for products to be registered in Australia. Therefore, applicants should conduct efficacy trials within Australia under typical farm management practices covering relevant geographical regions and the following additional guidance is provided to assist you in conducting these trials. If you follow this additional guidance, your data should generally be sufficient for the APVMA to assess its confidence in the product’s efficacy given Australia’s unique conditions.
This preamble refers to the following World Association for the Advancement of Veterinary Parasitology (WAAVP) guideline: Holdsworth, P., Rehbein, S., Jonsson, NN., Peter, R., Vercruysse, J., Fourie, J., 2022, World Association for the Advancement of Veterinary Parasitology (WAAVP) second edition: Guideline for evaluating the efficacy of parasiticides against ectoparasites of ruminants, Veterinary Parasitology, vol. 302.
2. Parasite species
|
Parasite |
Species |
|---|---|
|
Lice |
In Australia, efficacy studies in sheep should use Bovicola ovis as the target parasite species |
|
Blowfly |
You should use Lucilia cuprina as the target parasite species for a claim for blowfly strike in your efficacy studies. |
|
Tick |
Rhipicephalus (Boophilus) microplus is the most important cattle tick in Australia, although Haemaphysalis longicornis, Ixodes holocyclus and Rhipicephalus sanguineus also occur. You should use Rhipicephalus microplus as the target parasite species in your efficacy studies, as well as the other parasite species (e.g. Ixodes holocyclus) if you propose to claim efficacy against such parasites. If you make claims against specific resistant strains of cattle ticks, you should also demonstrate efficacy against those strains. |
3. Types and number of trials
All studies should be conducted using the final formulation intended for marketing. The use of alternative formulations is only acceptable if adequate justification for doing so is provided.
|
Parasite |
Dose determination |
Dose confirmation |
Field studies |
||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Ixodidae (hard ticks) |
At least 2 |
At least 2 |
At least 2 field study sites in each geographical location being assessed. At least 3 geographical locations required.
As additional guidance, the APVMA recommends the number, location and timing of field trials for Rhipicephalus microplus set out in Table 2a.
For Ixodes holocyclus, 2 field trials are required in each geographic region. The 2 recommended geographic regions in Australia are coastal New South Wales and coastal Queensland. |
||||||||||||||||
|
Biting and nuisance flies |
At least 2 |
At least 2 |
A minimum of 4 trial sites to be selected from Table 2b, which sets out the number, location and timing of field trials for buffalo fly. At least 2 of these trial sites should be situated in Tropical Queensland and one in Central Queensland. The fourth site can be located in the South East, or in one of the other areas mentioned. Where the intention is to register the product for use on dairy cattle, a fifth site, located on a dairy farm in one of the regions listed, should also be chosen for an efficacy trial.
|
||||||||||||||||
|
Myiasis causing flies |
At least 2 |
At least 2 |
General recommendation: a minimum of 2 studies should be selected in 2 distinct geographical locations.
Strike flies: The sponsor must demonstrate that the test product when used, as directed, will be effective in a range of geographic environments as well as in animals of variable age, breed, sex, wool, length, etc. This will normally require a minimum of 5 to 10 well-conducted and strategically located regional field studies where adequate fly challenge is demonstrated. |
||||||||||||||||
|
Lice |
At least 2 |
At least 2 |
General: A minimum of 2 studies per geographical region with at least 2 geographical regions included in the study protocol.
Sheep: for products used on sheep off-shears or in short wool, the APVMA requires 5 studies conducted with mob sizes of not less than 300 and ideally at least 500 sheep, for at least 20 weeks. Three of these trials should be conducted with fine-wool merinos. Fine-wool merinos are defined as having wool less than 20 µm (microns) in diameter. A mob is defined as all the sheep treated with the test product being maintained together at all times throughout the trial period. At least 25 tagged tracer sheep should be included in each mob.
For products used on sheep in long wool, the APVMA requires 6 studies (2 each at 3, 6 and 9 months), 3 of which (one per wool length) should be conducted in fine-wool merinos, with mob sizes not less than 300 and ideally at least 500 sheep, for 20 weeks or until next shearing (whichever occurs first). At least 25 tagged tracer sheep should be included in each mob. |
||||||||||||||||
|
Mange and itch mites |
At least 2 |
At least 2 |
A minimum of 2 studies should be selected in each geographical location where each mite species resides in a region.
At least 2 geographical regions should be included in the study protocol. |
4. Timing of trials
Therapeutic and persistent efficacy field studies should be conducted at times consistent with the usual peak season for the target parasite in a region.
4.1. Claims and level of efficacy
|
Parasite |
Claims and levels of efficacy |
|---|---|
|
Lice |
The WAAVP guidelines refer generally to a ‘lice eradication/elimination’ claim (100%) and a ‘lice management’ claim (95%). For clarity and consistency in new and existing registered products, the APVMA uses the term ‘eradication’ for an ‘eradication/elimination’ claim and the term ‘control’ for a ‘lice management’ claim.
Eradication – This claim is only applicable to products applied off-shears or in short wool. ‘Eradication’ is defined as: ‘Elimination of all live lice and viable eggs from treated animals, as determined by inspection of sheep 52 weeks after treatment.’
Control – For products used off-shears and in short wool, ‘control’ is defined as: ‘Elimination of all live lice and viable eggs from treated animals, as determined by inspection of sheep 20 weeks after treatment.’
For products used in long wool, ‘control’ is defined as: ‘Reduction of the lice population by more than 95% after 90 days (or less as supported by data) in sheep examined in pen and field trials’.
For products used in long wool, if you present unequivocal evidence of a reduction in fleece damage caused by the lice at any time, then the 95% figure may be modified. The term ‘aids in control’ would apply. |
|
Blowfly |
Efficacy of at least 90%, supported by appropriate statistical analysis is recommended to demonstrate acceptable efficacy of the investigational product. |
|
Tick |
For single-host and multi-host ticks at least 95% efficacy is required for both therapeutic (control) and persistent efficacy claims |
|
Mites |
For each targeted mite species, the criterion for efficacy is to achieve statistically significant (p ≤ 0.05) differences in mite counts (all parasitic stages) between treated and negative control groups and at least 90% efficacy (from Days 14 to 56 of the study).
The WAAVP guidelines refer to ‘therapeutic efficacy’. In the interests of clarity and consistency for new and existing registered products, the APVMA will use the term ‘control’ and not ‘therapeutic efficacy’.
With respect to Psorergates ovis, ‘control’ is defined as: ‘Reduction of the mite population to non-detectable levels at all post-treatment examinations of treated sheep, in the presence of normal seasonal fluctuations in the population on untreated sheep kept under the same conditions’. |
|
Biting and nuisance flies |
Based on controlled studies (fly exposure houses) a level of confidence can be generated in performance of the test product with a percentage efficacy of at least 90% being considered an indicator of high performance. |
5. Adequacy of infestation
Animals should be infested with a suitable number of parasites. The adequacy of infestation should be addressed in terms of the statistical, parasitological and clinical relevance of the level of infestation. For a study to be considered valid, parasites should be recovered from at least 80% of the negative control animals at each post-treatment observation.
6. Rainfastness
The World Association for the Advancement of Veterinary Parasitology guidelines address rainfastness generally: ‘Where artificial rainfall is used in dose confirmatory studies to test the efficacy of a topically applied test product after heavy rain, the method of wetting used and the equivalent in terms of natural rainfall should be stated (e.g. artificial rain applied by sprinklers, equivalent to a rainfall of 20 millimetres in a storm lasting 30 minutes). The time of animal wetting before or after test product application should be recorded (e.g. zero, 2 hours, etc.)’.
For trials conducted for buffalo fly and cattle tick, the APVMA suggests as a guide that animals be subjected to the equivalent of 12.5 millimetres of rainfall over a 10-minute period.
7. Wool or hide damage
Given the importance of the wool and cattle by-product industries to Australian commerce, it is recommended that applicants collect and submit data on wool staining or damage, hide or skin damage, or damage to animal products.
8. Preamble for Appendix A of the WAAVP guideline: ticks on ruminants
8.1. Animals
The World Association for the Advancement of Veterinary Parasitology guidelines are silent on which cattle breed should be used in these studies. The APVMA prefers that you use Bos taurus cattle which are naturally less resistant to cattle tick infestation than Bos indicus cattle.
Animal welfare considerations, along with some legislative requirements, may restrict the intensity and longevity of tick exposure to experimental animals. However, it must not be overlooked that one of the principle aims of these types of studies is to demonstrate how the test product is likely to perform under field situations. In field situations, under conditions favourable for tick survival and replication, tick populations and subsequent tick infestation pressure on animals will be substantial. Dose determination and dose confirmation studies should mimic such 'in-field' tick infestation pressure to give the sponsor confidence that the proposed product is adequately efficacious, and development should proceed to field studies.
8.2. Acaricides for cleansing tick-infested cattle
Given the importance of maintaining tick-free areas in Australia, if products claim efficacy for cleansing tick-infested cattle before cattle are introduced into a tick-infested area, then multiple treatments, commonly within a period of 7 days, are used to ensure that cattle from infested or quarantined areas can be moved to tick-free country. Before moving these cattle, they are inspected by relevant authorities to ensure that there are no signs of tick life.
If you seek a claim for the cleansing of tick-infested cattle, you should conduct multiple treatments of infected cattle according to current movement control requirements and carry out efficacy assessments. However, examinations to support such a claim should include not only records of adult ticks collected or counted but also detailed observations of the presence of other tick stages on the animals after they have been treated.
9. Preamble for Appendix C of the WAAVP guideline: myiasis-causing parasites on ruminants
9.1. Field trials
The WAAVP guidelines recommend that you include a negative control group in field trials to demonstrate adequate fly-strike pressure. We consider that as an alternative to including a negative control group in field trials, you may provide daily rainfall data, temperature data, wind speed data and fly-trap records of catches of Lucilia cuprina, and any other data that demonstrate adequate fly pressure. You should also include at least one positive control group (sheep treated with an appropriate registered product) in the field trials in that case. Hearsay by farmers or local advisory people would not be considered acceptable evidence of fly pressure.
9.2. Fly-strike dressings
When assessing fly-strike dressings as treatments against existing strikes, the World Association for the Advancement of Veterinary Parasitology guidelines recommend that ‘the test product should preferably demonstrate efficacy in killing active, advanced third instar field-derived larvae on sheep, as this is the stage most likely to be detected by farmers’.
We recommend that the test product should demonstrate efficacy in killing active, advanced third-instar field-derived larvae on sheep, as this is the stage most likely to be detected by farmers.
10. Preamble for Appendix D of the WAAVP guideline: lice and sheep keds on ruminants
10.1. Terminology
- Off-shears: within 24 hours after shearing
- Short wool: at least 24 hours and up to 6 weeks after shearing
- Long wool: at least 6 and up to 43 weeks after shearing
10.2. Lice counts
For determining the level of infestation of biting lice in sheep, the World Association for the Advancement of Veterinary Parasitology guidelines specify the examination of 40 sites (partings), about 10 cm wide, in total per animal or 80 sites (partings), about 5 cm wide, per animal. The sites should be spaced so that they are representative of the full area of the body covered by the fleece on each side of the sheep. In addition, the APVMA recommends that you divide the examination sites equally on each side of the animal, that is, 20 (10 cm) or 40 (5 cm) sites should be examined on each side of the body (total = 40 (10 cm) or 80 (5 cm) sites). Furthermore, the APVMA recommends that you distribute the number of partings on each side of the body equally between the neck, shoulder, withers, rump and flank, that is, 4 (10 cm) or 8 (5 cm) partings at each location on each side of the body.
10.3. Level of lice infestation
The World Association for the Advancement of Veterinary Parasitology guidelines specify that sheep in field studies should have at least a moderate infestation of lice (30 lice per animal) at the pre-treatment examination. The APVMA also recommends that sheep in field studies should have at least a moderate infestation of lice at the pre-treatment examination; however, the APVMA defines the level of infestation as follows:
- Low infestation: less than 1 louse per 10 cm parting
- Moderate infestation: 1 to 5 lice per 10 cm parting
- Heavy infestation: more than 5 lice per 10 cm parting
Therefore, sheep with a moderate infestation would have at least 40 lice per animal (based on 40 x 10 cm partings).
10.4. Persistency studies for lice
For persistent efficacy studies in sheep, the World Association for the Advancement of Veterinary Parasitology guidelines recommend infestation with 50 lice on the shoulder and/or flank. The APVMA finds this recommendation to be unclear, that is, the total could be 50 or 100 lice. To clarify, the APVMA recommends infestation with 50 live lice on the right shoulder and right flank (total = 100). The APVMA also recommends that the studies be conducted in merinos.