RESUMO
Haemonchus contortus is the most prevalent and important gastrointestinal nematode (GIN) in small ruminants. Since it reduces the packed cell volume (PCV), causing anemia, early diagnosis can be used for targeted selective treatment (TST) of sheep, reducing antiparasitic drug use and anthelmintic resistance. This study aimed to predict PCV values through near-infrared spectroscopy (NIRS) and to develop a classification and diagnosis model of H. contortus infection using PCV values, eggs per gram of feces (EPG) counts and mean daily weight gain (DWG). A total of 1728 spectra were collected from blood samples of 216 lambs with a portable NIR spectroscope. In parallel, other parameters indicative of infection were measured: PCV by hematocrit, FAffa MAlan CHArt (FAMACHA) scores, EPG and DWG. To evaluate the relationship between NIRS spectra and the evaluated parameters, principal component analysis (PCA) was used for an exploratory analysis, regression by the partial least squares method (PLS) for the prediction of PCV values via NIRS, and PCA linear discriminant analysis (PCA-LDA) as a classification model for diagnosis. The absorption peaks in the NIRS region associated with the excitation of overtones of nitrogen-hydrogen (N-H) functional groups of proteins had a strong impact on the principal components (PCs), indicating that blood proteins, especially hemoglobin, can be estimated by the NIRS technique. The model for predicting PCV by PLS presented a standard error of prediction of 2.53, root-mean-square error of 2.48, and coefficient of determination of 0.84, indicating good correlation between the PCV values predicted by the model and the PCV obtained by hematocrit. The PCA-LDA model presented 93.33% sensitivity and 82.18% accuracy, both higher than those of the FAMACHA method, as was expected for resilient Morada Nova lambs. The multivariate models associated with the NIRS technique reported here can be used in the future as a quick and versatile tool for H. contortus infection diagnosis and TST application in lambs.
Assuntos
Anemia , Hemoncose , Haemonchus , Nematoides , Doenças dos Ovinos , Ovinos , Animais , Espectroscopia de Luz Próxima ao Infravermelho , Hematócrito/veterinária , Anemia/diagnóstico , Anemia/parasitologia , Anemia/veterinária , Aumento de Peso , Fezes/parasitologia , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/parasitologia , Hemoncose/diagnóstico , Hemoncose/tratamento farmacológico , Hemoncose/veterinária , Contagem de Ovos de Parasitas/veterináriaRESUMO
O controle das endoparasitoses gastrintestinais em pequenos ruminantes tem sido tradicionalmente realizado por meio do uso indiscriminado dos anti-helmínticos, porém essa prática tem resultado em grande pressão de seleção de parasitas resistentes. Métodos seletivos (ex: FAMACHA/FMC e contagem de ovos nas fezes/OPG) e que apresentem boa sensibilidade para identificar os animais que necessitam receber o tratamento químico são importantes alternativas aos métodos tradicionais. O objetivo desse trabalho foi determinar a sensibilidade e a especificidade do método FMC, usado para detectar anemia causada por Haemonchus contortus em ovinos da raça Suffolk, em duas categorias de alta suscetibilidade; cordeiros lactentes e ovelhas durante a fase de lactação. A conjuntiva ocular de 42 cordeiros lactentes e 35 ovelhas em lactação foi avaliada usando o método FMC, em intervalos de 14 dias, durante cinco meses. O hematócrito (Ht) foi utilizado como padrão-ouro para avaliação clínica de anemia dos animais. Para o cálculo de sensibilidade e especificidade, diferentes critérios foram utilizados: animais classificados como 4 e 5 ou 3, 4 e 5 e anêmicos pelo Ht (teste positivo); animais classificados como 1, 2 e 3 ou 1 e 2 e não anêmicos pelo Ht (teste negativo). Três valores de corte para Ht (≤22%, ≤19% ou ≤15%) foram utilizados para confirmar a anemia. Entre os gêneros observados nas coproculturas, H. contortus (61,5%) e Ostertagiasp (21,3%) foram os mais prevalentes. Em ambas as categorias, a inclusão do FMC 3 como teste positivo, elevou a sensibilidade mas reduziu a especificidade do método. Quando o FMC 3 foi considerado anêmico, o percentual de falsos negativos foi próximo a zero, no entanto, houve aumento no número de tratamentos aplicados em animais não anêmicos (falso positivo). Durante as avaliações, a maior parte dos cordeiros (73%) e das ovelhas (53%) permaneceu nas categorias de FMC 1 e 2...(AU)
The control of gastrointestinal parasites in small ruminants has traditionally involved the indiscriminate use of anthelmintic drugs that resulted in a high parasite selection pressure for anthelmintic resistance. Selective methods (ex.: FAMACHA/FMC and faecal egg count/EPG), which have good sensitivity to identify animals that need drug treatment, are important alternative methods for parasite control. The objective of this study was to determine the sensitivity and specificity of the FMC method to detect clinical anemia caused by Haemonchus contortus in two highly susceptible categories of Suffolk sheep; suckling lambs and lactating ewes. The ocular conjunctivae of 42 suckling lambs and 35 lactating ewes were evaluated using the FMC method at 14 days interval for five months. Hematocrit (Ht) served as the gold standard for anemia evaluation. To calculate the sensitivity and specificity of the FMC method, different criteria were adopted: animals classified as 4 and 5, or 3, 4 and 5, were considered to be anemic (positive test), and animals classified as 1, 2 and 3, or 1 and 2 were considered to be non-anemic (negative test). Three standard values of Ht (≤22%, ≤19% or ≤15%) were used to confirm anemia. Among the prevalent genera of helminths H. contortus (61.5%) and Ostertagia sp. (21.3%) were the most predominant species in the coproculture. For both categories, the inclusion of FMC 3 as a positive test increased the sensitivity but decreased the specificity of the method. When FMC 3 was included as anemic, the percentage of false negative was close to zero, but a greater number of treatments were applied to non-anemic animals (false positive). Most of the lambs (73%) and ewes (57%) remained in categories 1 or 2 throughout the trial...(AU)
Assuntos
Animais , Lactente , Ruminantes/parasitologia , Haemonchus/parasitologia , Haemonchus/patogenicidade , Anemia/veterinária , Hematócrito/veterinária , Helmintíase/diagnóstico , Helmintíase/parasitologiaRESUMO
O controle das endoparasitoses gastrintestinais em pequenos ruminantes tem sido tradicionalmente realizado por meio do uso indiscriminado dos anti-helmínticos, porém essa prática tem resultado em grande pressão de seleção de parasitas resistentes. Métodos seletivos (ex: FAMACHA/FMC e contagem de ovos nas fezes/OPG) e que apresentem boa sensibilidade para identificar os animais que necessitam receber o tratamento químico são importantes alternativas aos métodos tradicionais. O objetivo desse trabalho foi determinar a sensibilidade e a especificidade do método FMC, usado para detectar anemia causada por Haemonchus contortus em ovinos da raça Suffolk, em duas categorias de alta suscetibilidade; cordeiros lactentes e ovelhas durante a fase de lactação...
The control of gastrointestinal parasites in small ruminants has traditionally involved the indiscriminate use of anthelmintic drugs that resulted in a high parasite selection pressure for anthelmintic resistance. Selective methods (ex.: FAMACHA/FMC and faecal egg count/EPG), which have good sensitivity to identify animals that need drug treatment, are important alternative methods for parasite control. The objective of this study was to determine the sensitivity and specificity of the FMC method to detect clinical anemia caused by Haemonchus contortus in two highly susceptible categories of Suffolk sheep; suckling lambs and lactating ewes...
Assuntos
Animais , Lactente , Anemia/veterinária , Haemonchus/parasitologia , Haemonchus/patogenicidade , Ruminantes , Helmintíase/diagnóstico , Helmintíase/parasitologia , Hematócrito/veterináriaRESUMO
Background: Gastrointestinal nematode infections are a major problem for sheep production, leading to large economic losses as a result of the high costs for prevention and treatment. In helminthiasis, the most common clinical signs are weight loss, submandibular edema, diarrhea, and anemia. Among the many nematodes, stands out in the Brazilian states Haemonchus contortus and Trichostrongylus colubriformis, as well as these parasites have developed a number of anthelmintic resistance. Therefore, the aim of this study was to evaluate the cost-benefit of different antihelminthic protocols in naturally infected sheep.Material, Methods & Results: The study was conducted for one year in a sheep farm located in Southern Brazil. Three groups (A, B and C) with 10 adult sheep each were used. The group A was treated without drug rotation, and levamisole hydrochloride was used at intervals of 60 days. The group B was treated with levamisole hydrochloride at months 2, 4, 8 and 12 and albendazole at month 6 (antiparasitic treatment with pharmacological rotation). Animals from the group C were treated after selection by the Famacha method, which is based on the degree of anemia of their mucous ocular membranes. The results showed that the animals of the group C had lower values of eggs per gram of feces (EPG), and thus, they were treated more efficiently...
Assuntos
Animais , Anti-Helmínticos/administração & dosagem , Anti-Helmínticos/economia , Análise Custo-Benefício , Ovinos/parasitologia , Infecções por Nematoides/economia , Infecções por Nematoides/prevenção & controle , Infecções por Nematoides/veterináriaRESUMO
Background: Gastrointestinal nematode infections are a major problem for sheep production, leading to large economic losses as a result of the high costs for prevention and treatment. In helminthiasis, the most common clinical signs are weight loss, submandibular edema, diarrhea, and anemia. Among the many nematodes, stands out in the Brazilian states Haemonchus contortus and Trichostrongylus colubriformis, as well as these parasites have developed a number of anthelmintic resistance. Therefore, the aim of this study was to evaluate the cost-benefit of different antihelminthic protocols in naturally infected sheep.Material, Methods & Results: The study was conducted for one year in a sheep farm located in Southern Brazil. Three groups (A, B and C) with 10 adult sheep each were used. The group A was treated without drug rotation, and levamisole hydrochloride was used at intervals of 60 days. The group B was treated with levamisole hydrochloride at months 2, 4, 8 and 12 and albendazole at month 6 (antiparasitic treatment with pharmacological rotation). Animals from the group C were treated after selection by the Famacha method, which is based on the degree of anemia of their mucous ocular membranes. The results showed that the animals of the group C had lower values of eggs per gram of feces (EPG), and thus, they were treated more efficiently...(AU)