Fernanda Rosalinski-Moraes

Sensitivity and specificity of the FAMACHA © system in Suffolk sheep and crossbred Boer goats

Sheep and goats are the species of farm animal with the highest growth rate in Paraná State. The main problems facing Paraná State flocks are gastrointestinal parasites and anthelmintic resistance. One of the newest resources used to slow down the development of anthelmintic resistance is the FAMACHA(©) system, a selective method useful for controlling gastrointestinal verminosis in small ruminants. The purpose of the present research was to evaluate the sensitivity and specificity of the FAMACHA(©) system in sheep and goats and to compare the results for both species. The conjunctivae of 83 Suffolk ewes and 60 adult crossbred Boer does were evaluated by the same trained person using the FAMACHA(©) system. The packed cell value (PCV) served as the gold standard for clinical FAMACHA(©) evaluation. To calculate the sensitivity and specificity of the FAMACHA(©) system, different criteria were adopted in turn: animals classified as FAMACHA(©) (F(©)) 4 and 5, or 3, 4 and 5, were considered to be anemic (positive test), and animals classified as F(©)1, 2 and 3, or 1 and 2 were considered to be non-anemic (negative test). Three standard values of PCV, namely ≤19%, ≤18% or ≤15%, were used to confirm anemia. At all cut-off levels, the sensitivity increased if F(©)3 animals were included as being anemic. However, changes in levels of sensitivity were associated with reciprocal changes in specificity. The sensitivity was higher for sheep than for goats, excepting when the criteria included PCV≤18 and F(©)3, F(©)4 and F(©)5 were considered positive. In contrast, the specificity was always lower in sheep for any criteria adopted. Other than in goats, using the ≤15 cut-off level for sheep, it is possible to opt not to drench the animals that were shown to be F(©)3 because the sensitivity is still high, indicating that few animals that should have been drenched were overlooked. In goats, in contrast, the low sensitivity at all cut-off levels made it too risky to leave F(©)3 animals undrenched. Even though the number of correct treatments for goats was always higher than that for sheep, the opposite was true for the kappa index for all the criteria tested. Therefore, the FAMACHA(©) system is suitable for the identification of anemic animals of both species. It is necessary that all small ruminants classified as FAMACHA(©) level 3 are also treated to increase the sensitivity of the method.

Assessment of a hands-on method for FAMACHA© system training.

The FAMACHA(©) system is a method for selective anthelmintic treatment comprising early detection of haemonchosis in sheep and goats. In order to evaluate the hands-on training methodology and the learning level of the participants, we analyzed data from 30 training events involving 47 training classes conducted in the State of Paraná, Brazil, from July/2009 to May/2011, during which period a total of 1004 participants did 20,080 FAMACHA(©) classifications. In the practical training sessions, each participant individually evaluated 20 animals with known haematocrit values. Every participant per training event was given a unique number, whereupon each of the animals in a given event was FAMACHA(©) classified by all the trainees involved, in the same trainee number sequence. After each consecutive animal had been evaluated by every one of the participants, its haematocrit and corresponding FAMACHA(©) category were announced before the next animal was presented. The number of persons in training, which ranged from 5 to 39 per session, did not significantly affect the average error of the groups of participants involved (p>0.05). The average error in the classification of the first animal on a scale with a perfect score of zero was 2.5, significantly greater than the error of 0.56 of the twentieth one (p<0.05), indicating an inverse relationship between the error and the cumulative number of animals already evaluated by each trainee involved, with the reduction in mean error per animal in a given training event found by linear regression to be 0.0713. When the same animal was assessed twice in the same training event, the average error of the second evaluation (1.05) was significantly lower than the 1.70 of the first (p<0.05). While the total of 686 sheep used in the training events (73%) was considerably larger than the corresponding number of 254 goats (27%), the average statistical errors, respectively, 1.34 and 1.23, were not significantly different (p>0.05). Similarly, the average errors in FAMACHA(©) classification were not significantly influenced by the occupation or gender of the participants, nor whether there were animals in all five FAMACHA(©) categories or only in categories 1, 2, 3 and 4 per training event (p>0.05).

FAMACHA© system assessment by previously trained sheep and goat farmers in Brazil.

The aim of this study was to evaluate the degree of adoption and the correct use of the FAMACHA© system amongst sheep and goat farmers trained in a previous hands-on course. A survey was carried out with 1375 people who received FAMACHA© training from July 2009 to May 2011 in Paraná State, Brazil. The survey was conducted from March 2012 to May 2013. Firstly, a questionnaire was applied with specific questions for farmers about their anthelmintic (AH) treatment practices before and after the FAMACHA© training. In a second step, eight of the questionnaire respondents classified as sheep or goat farmers were contacted for an in loco visit during which the application of the FAMACHA© system was evaluated in the respective farms and blood samples were collected from 20 animals to calculate sensitivity and specificity. A total of 124 farmers responded the questionnaire (9% of project participants). Farmers accounted for 48.4% of total responses. Half of these farmers (51.6%) reported losses related to parasites in their property before the training. Antiparasitic treatments, at fixed intervals, were responsible for 93.1% of deworming practices before the training project. FAMACHA© was unknown for 51.7% of the respondents, and 31% knew the chart, but did not use it. After the project, 69% had adopted the system and 83% assessed the animals at regular intervals. However, 18.9% did not evaluate all animals. During the in loco visits, problems reported included the incorrect exposure of the ocular mucosa (50% of farmers) and not using the chart (87.5%). Also, 62.5% did not keep records of the FAMACHA© assessment history of the flock. However, sensitivity was 100%, with 0% false negatives. We conclude that, amongst farmers who adopted the system, despite some methodological errors regarding its use, the objectives were met in terms of reducing the number of anthelmintic treatments and providing anemic animals with AH treatment. Trained farmers seemed to require technical guidance post-training to promote effective use of the FAMACHA© system.

Corrigendum to “Sensitivity and specificity of the FAMACHA© system in Suffolk sheep and crossbred Boer goats” [Vet. Parasitol. 190 (2012) 114–119]

The authors reported an error in Table 2; the titles of the true-negative and true-positive columns are switched, and a corrected versionof Table 2 follows below.