Andréia Buzatti

Partial selective treatment of Rhipicephalus microplus and breed resistance variation in beef cows in Rio Grande do Sul, Brazil.

Rhipicephalus microplus infestation causes heavy losses in cattle. The majority of farmers control the cattle tick by using long-acting drugs throughout the year, which evidently increases selection pressure for drug resistance. Partial selective treatment (PST) may be used to directly reduce selection pressure by treating only the portion of the herd that is most infested. The objective of this work was to determine the effect of PST in two herds of beef cows and the effect of breed tolerance. The Santiago (n=306 animals) and the São Francisco de Assis (n=204 animals) herds were composed of up to eight pure breeds of Bos taurus and Bos indicus and their crosses and were evaluated during the first and second (8 months) tick generations. Ticks larger than 4.5mm were counted on one side of the animal, and the animals were treated when numbers exceeded 20 ticks per host. On both farms, the tick-tolerant breeds with a high proportion of B. indicus (Braford, Brangus, and Nellore) consistently carried fewer ticks than Charolais. The economical evaluation showed an average profit margin in the use of PST of 674.25% and 1394.5% on the Santiago and São Francisco de Assis farms, respectively, in comparison to all-herd treatment. These results indicate that PST is a reliable tool for health management and may be used as a standard protocol for tick control with significant economic benefits on farms. In addition, the maintenance of the highest possible tolerant/resilient breeds is also an essential factor that should be considered in todays more sustainable animal production systems.

Evaluation of resistance in a selected field strain of Haemonchus contortus to ivermectin and moxidectin using the Larval Migration on Agar Test

Haemonchus contortus e uma das causas mais comuns e economicamente significativas de doenca em producoes de pequenos ruminantes em todo o mundo, e os programas de controle de parasitas nematoides - incluindo H. contortus - baseiam-se principalmente no uso de drogas anti-helminticas. A consequencia da utilizacao desses compostos, como sendo a unica estrategia sanitaria para evitar infeccoes por parasitas, tem sido a reducao da eficacia de todos os produtos quimioterapicos, selecionando fortemente para resistencia. O desenvolvimento generalizado da resistencia anti-helmintica e a dificuldade de seu diagnostico precoce tem sido uma grande preocupacao para o manejo sustentavel de parasitas no campo. O objetivo desta pesquisa foi determinar e comparar o efeito da ivermectina (IVM) e da moxidectina (MOX) em um isolado de campo selecionado de H. contortus com um estado de resistencia conhecido, utilizando o teste in vitro de migracao de larvas em agar (LMTA). Larvas de terceiro estagio de um isolado de H. contortus selecionado foram obtidas a partir de culturas de fezes de ovinos infectados experimentalmente e incubadas em onze concentracoes diluidas crescentes de IVM e MOX (6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072 e 6144µg/mL). As curvas sigmoides de dose-resposta foram obtidas utilizando o valor de R2 >0,90 e a dose de concentracao letal (CL50) para as drogas anti-helminticas testadas, utilizando um modelo logistico de quatro parâmetros. O valor de CL50 para MOX foi significativamente menor do que para IVM (1,253µg/mL e 91,06µg/mL), identificando o isolado de H. contortus como consideravelmente menos suscetivel a IVM em comparacao a MOX. Alem disso, o LMTA mostrou uma alta consistencia (p<0,0001) e pode ser uma ferramenta util de diagnostico para monitorar o status de resistencia de IVM e MOX em isolado de campo de H. contortus, assim como ser utilizado de forma oficial e em rotina para programas de monitoramento das drogas sob a demanda do Ministerio da Agricultura (MAPA).

Método FAMACHA para detectar anemia clínica causada por Haemonchus contortus em cordeiros lactentes e ovelhas em 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. 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. Only 5% of the lambs and 8% of the ewes were classified as the two major stages of anemia (4 and 5). The results indicate that the FMC is a safe method to be used in lambs and lactating ewes with clinical anemia from H. contortusinfection. For both categories, it was necessary to include FMC 3 as a positive condition to increase the sensitivity of the method and to reduce the risk of death of undiagnosed anemic animals (false negatives).

Atividade ovicida e larvicida do extrato hidroalcoólico de Artemisia annua sobre parasitas gastrintestinais de bovinos

Gastrointestinal parasites cause economic losses to the cattle production, in Brazil and worldwide, mainly caused by Bunostumom sp., Cooperia sp. and Trichostrongylus sp. The aim of this study was to determine the in vitro efficacy of hydroalcoholic extract of Artemisia annua (H.7) against these parasites. The H.7 was produced after 7 days of storage at 4°C and then lyophilized. With this herbal the egg hatch test (EHT) and larval migration inhibition (LMI) were performed,in six replicates with different concentrations (0.78 to 50mg/mL). To analyze the chemistry composition the complete phytochemical screening was done. In EHT efficiency ranged from 94.08±2.58% at the highest concentration to 15.67± 0.97% in the lowest concentration. In LMI test the values ranged from 90.05±0.55% to 4.12±0.46%. Phytochemical tests showed many chemical compounds with anthelmintic properties. The results obtained in biochemical tests together with those found in in vitro tests showed that the extract produced has the potential to combat intestinal nematodes of cattle. Further studies should be conducted to maximize the effectiveness of H.7 and other extractions from A. annua, because it demonstrated excellent results in both experiments.

Gene silencing of Dim-1, a member of the disorganized muscle family, in Haemonchus contortus

RNA interference has been widely used in parasites. In Haemonchus contortus, reproducible silencing has been reported; however, in this species an altered phenotype has been observed for only a few genes silenced by RNA interference. The aim of this work was to evaluate the effect of silencing Dim-1, a member of the disorganized muscle family on third stage larvae (L3) of H. contortus. Effective silencing of Dim-1 in L3 led to reduced L3 migration and slowed larval development from L3 to early L4. To our knowledge, this is the first report to demonstrate Dim-1 silencing affecting phenotypic characteristics of this parasite.

Efeito anticoccidiano de extrato hidroalcoólico de Artemisia annua em camas de aves contaminadas com Eimeria sp

The aim of this study was to determine the efficacy of hydroalcoholic extract of Artemisia annua against oocysts of Eimeria sp. in contaminated poultry beds. The extract was produced after 7 days of storage at 4°C, which was used to perform the phytochemical screening; the artemisinin measurement; the total phenolic; antioxidant testing and toxicity test. To test the anticoccidial activity, the birds space composed of shaver trees, were contaminated with 5000 oocysts. Four treatment were formed, in triplicate, were used in different concentrations as G1: 12mg/mL, G2:= 9mg/mL, G3: 6mg/mL, and C-: water. After contamination 800 mL of the herbal at different concentrations were sprayed on the bed and collected, in triplicate, 10 cm2 each site, randomly, at times: 0, 3, 6, 24, 48, and 72 hours after application. In phytochemical analysis, were shown compounds with antiparasitic properties, such as flavonoids and tannins. The herbal contained 59.409±1.47mg/dL artemisinin. The product at a concentration of 12mg.mL-1 showed efficacy from 44.25 to 40.71%. The results of biochemical tests, with the in vitro test showed that the extract has produced high potential for combating Eimeria sp.

Occurrence of gastrointestinal parasites in wild animals in State of Paraná, Brazil

The objective of this study was to determine the prevalence and diversity of gastrointestinal parasites in fecal samples from wild birds and mammals from the State of Paraná. In total, 220 stool samples were sent to Parasitic Diseases Laboratory of the Federal University of Paraná during 13 months (Jan/2013-Jan/2014). A total of 52.7% (116/220) of the animals were positive for cysts, oocysts, eggs and/or trophozoites. In birds, the positivity rate was 37.9% (25/66) and mammals was 59.1% (91/154). Strongyloidea superfamily eggs were observed in 37.3% (82/220) of the samples, Eimeria spp. in 10% (22/220), and Trichuris spp. in 4.5% (10/220). The most frequent mammal species were llamas (Lama glama), and dromedaries (Camelus bactrianus) with infection rate of 70.1% (54/77) and 60.8% (14/23), respectively. In other hand, cockatiels (Nymphicus hollandicus) and ring necks (Psittacula krameri), were the most researched birds, with infection rate of 20% (40/50) and 100% (6/6), respectively. A high prevalence of gastrointestinal parasites was observed in most of wildlife animals. Further investigations should be conducted focusing on parasite control strategies and the conservation measurements for harmonizing the human-animal interaction on the long-term, reducing associated health risks.