The diagnostics of ruminant parasites remains one of the cornerstones for parasite control best practices. Field veterinarians have several techniques at their disposal (fecal egg count, ...coproculture, FAMACHA®, plasma pepsinogen, ELISA-Ostertagia, ELISA-Fasciola, Baermann and ELISA-Lungworm) for the identification and/or quantification of gastrointestinal nematodes, lungworms and liver fluke infecting small ruminants and cattle. Each of these diagnostic tools has its own strengths and weaknesses and is more appropriate for a specific production operation and/or age of the animal (young and adults). This review focuses on the usability and interpretation of the results of these diagnostic tools. The most advanced technical information on sampling, storage, advantages and limitations of each tool for different types of production operations and animal categories is provided.
The present study attempted to verify the prevalence of and risk factors for diarrhea-causing agents in dairy calves from Brazil. Additionally, ages with a higher risk of occurrence for each agent ...were verified by means of the receiver operating characteristic (ROC) curve. The collections were performed on 39 farms, belonging to 29 municipalities located in eight states of Brazil. It was possible to conclude that the prevalence of Coronavirus, Rotavirus,
Cryptosporidium
spp.,
Eimeria
spp., and nematodes was 7.20% (95% CI 4.54–9.78), 6.37% (95% CI 3.85–8.89), 51.52% (95% CI 45.26–55.57), 3.46% (95% CI 2.24–4.67), and 3.46% (95% CI 2.24–4.67), respectively. Ages with higher probabilities of occurrence of these diseases in calves were < 10, > 8, > 6, > 37, and > 36 days, respectively. Diarrhea occurred more significantly (
P
< 0.0001) in animals less than 21 days old and mainly on those receiving milk through automatic feeders (
P
< 0.001).
Cryptosporidium
spp. were a risk factor for the occurrence of Rotavirus, and vice versa (
P
= 0.0039) and presented a positive correlation with Coronavirus (
P
= 0.0089). Calves that drink water from rivers, streams, and ponds had a higher chance of being infected by
Eimeria
spp. (
P
< 0.0001), as well as developing infection by nematodes (
P
< 0.0001). The results found in this study highlight the importance of studying the agents of diarrhea together, once they act as coinfection where the losses triggered for the owners will involve some of these agents simultaneously.
This work investigated the mechanical transmission of
Trypanosoma vivax
by
Stomoxys calcitrans
to cattle in a region without a cyclic vector. The study involved two experiments, one with calves ...experimentally infected with
T. vivax
, in the acute phase of trypanosomosis (Experiment 1) and the other in the chronic phase (Experiment 2). In both experiments, two transmission methods were used with flies that had not fed for 24 h or had never fed: (i) Method 1: flies released freely in cattle pens (≈3,300 flies/pen for 10 days); and (ii) Method 2: flies placed in a feeding chamber (12 flies/animal). To develop Method 1 in the two experiments (acute and chronic phases),
T. vivax
-positive animals were kept with
T. vivax
-negative animals. Periodically, the Brener method, Woo method, blood smears, cPCR, ELISA, IFAT, and Imunoteste® were performed to detect
T. vivax
in the animals. We also recorded the animals’ head tossing and hoof stomping and the number of flies near the pens’ inner walls. Subsequently, biological testing was performed using lambs. For Method 2 in both experiments, flies inside the feeding chamber first fed on
T. vivax-
positive animals and later on negative animals. In both experiments and methods, we examined the flies for the presence of
T. vivax
through blood smears and cPCR of the proboscis and abdomen. In Experiment 2 (chronic phase), a test was conducted to determine how long trypomastigotes forms could survive on the blood of animals with different levels of parasitemia. None of the animals (calves and lambs) became infected with
T. vivax
or showed antibodies against it. During the evaluation period, the animals in the presence of the flies exhibited more hoof stomping and head tossing compared to those without flies (control). Additionally, there was an increase in the number of flies in the pens during the experiment. Only in Experiment 1 (acute phase) were
T. vivax
trypomastigotes and DNA found in the abdomen of the flies but not in the proboscis. In Experiment 2 (chronic phase), higher concentrations of trypomastigotes per milliliter of blood were associated with a shorter the lifespan of this stage of the parasite. In conclusion, under the variable conditions of the experiments (hosts, number of flies, and level of parasitemia),
S. calcitrans
was unable to mechanically transmit
T. vivax
to cattle.
This study describes the effectiveness of a novel active pharmaceutical ingredient, fluralaner (isoxazoline class), against important ectoparasites infesting cattle in Brazil. A total of 13 studies ...involving a 5% fluralaner-based pour-on formulation (Exzolt 5%; further referred to as Exzolt) were conducted. Specifically, the effectiveness of this formulation was studied against Rhipicephalus microplus (6 studies), Cochliomyia hominivorax larvae (4 studies), Dermatobia hominis larvae (1 study) and Haematobia irritans flies (2 studies). The therapeutic efficacy of Exzolt was found to exceed 98% at 4 days post treatment (DPT), while persistent efficacy (> 90% efficacy) against repeated infestations of R. microplus was observed for up to 79 DPT. In field studies, greater than or equal to 98% therapeutic efficacy was demonstrated at all study sites by 7 DPT, and a persistent efficacy (> 90% efficacy) was observed for 42, 49 or 56 DPT. Exzolt prevented C. hominivorax eggs from developing to the larval stage, thus mitigating the development of myiasis in cattle naturally and artificially infested with this screworm. The efficacy of Exzolt against D. hominis larvae was 98% at 3 DPT, while persistent efficacy (> 90% effectiveness) was found to last for up to 70 DPT. Against H. irritans, Exzolt showed therapeutic efficacy (greater than or equal to 90%) within the first day of treatment at both study sites, while persistent efficacy (greater than or equal to 90%) was observed for 7 DPT at one site and for 21 DPT at the other site. Overall, the results from these studies confirm that Exzolt is therapeutically efficacious against the most important ectoparasites infesting cattle in Brazil. The novel active pharmaceutical ingredient, fluralaner, provides a new treatment option for farmers to control cattle ectoparasites, especially where there is resistance to other chemical classes. In addition, an effective control of ectoparasites will improve overall cattle health and well-being as well as production.
Rainfall incidence as a risk factor for umbilical myiasis by Cochliomyia hominivorax in newborn beef cattle and the preventive and curative efficacies of injectable and topical products against its ...larvae were evaluated. The prevalence of navel myiasis did not differ between sex, however, it did differ between seasons of the year, independent of animal sex, with it being higher in the rainy season than in the dry season for both sexes (males 64.6%, females 62.1%). During the rainy season, rains occurred intermittently and the number of rainy days in a week had a direct influence on prevalence, with an increase (≥87%) in the number of calves with navel myiasis caused by C. hominivorax. When it rained intermittently for four, five and six days in a week during the rainy season, calves had ≈12, 24 and 11 times greater chances, respectively, of having navel myiasis compared to a week without rain during the rainy season. The injectable products did not reach preventive efficacies higher than 35%, while all treatments of topic products reached 100% preventive efficacy at 10 days post-treatment. Only the formulations with 30% dichlorfenthion and 0.32% fipronil achieved 100% curative efficacy. The results reinforce the need for intensified inspection and healing of the umbilicus during the rainy season, mainly during rainier weeks. Furthermore, topical formulations may be a better alternative as a preventive treatment than avermectin formulations. However, the curative efficacy of the topical product containing dichlorvos did not demonstrate a relationship with preventive efficacy for newborn calves.
•Navel myiasis is more prevalent in rainy season.•Calves born in weeks with more intermittently rainy days are more likely to have navel myiasis.•Topical products had better preventive efficacy than injectables ones.•Topical products preventive efficacy results differed from the curative efficacy.
Eimeria
are ubiquitous parasites and eimeriosis treatment is based on coccidiostats or coccidicides used prophylactically, metaphylactically, or therapeutically. The long-term efficacy of toltrazuril ...(TZR, 15 mg/kg) against experimentally infected naïve calves was investigated. Seven groups (six treated and one control) of six animals each were formed. Animals of each group received a single TZR prophylactic oral treatment on days − 42, − 35, − 28, − 21, − 14, and − 7 before the challenge with infectious sporulated oocysts of
Eimeria
spp. (100,000 oocysts: 59.5%
E. zuernii
, 38.1%
E. bovis
, 1.2%,
E. alabamensis
, and 1.2%
E. ellipsoidalis
). The long-term efficacy was assessed based on
Eimeria
spp. oocyst excretion by fecal oocyst counts. Three calves from the control group presented diarrhea with blood, which was not observed in animals belonging to the treatment groups. The TZR achieved efficacy greater than 95.0% up to 14 and 7 days. This formulation showed efficacy above 95% for 7 to 14 days, between 82 and 84% for 21 to 28 days and between 50 and 64% for 35 to 42 days.
Although co-infections of
Trypanosoma vivax
,
Anaplasma
spp., and
Babesia
spp. have been reported, knowledge gaps remain that need to be addressed. The present study evaluated the efficacy of ...enrofloxacin (7.5 mg/kg) against
A. marginale
in naturally infected cattle and cattle experimentally co-infected with
T. vivax
by observation of the variation in
A. marginale
parasitemia and packed cell volume (PCV) for 39 days. Bovines were distributed into two groups, each with six calves: T01 = animals immunosuppressed with dexamethasone and with latent anaplasmosis; T02 = animals immunosuppressed with dexamethasone, with latent anaplasmosis and experimentally co-infected with
T. vivax
on day 0 (D0). Animals of both groups were immunosuppressed with dexamethasone and received enrofloxacin (7.5 mg/kg) whenever mean values of parasitemia for
A. marginale
were ≥ 5% per group. Cattle of group T02 were also treated with isometamidium chloride (0.5 mg/kg) on D25. On D17 and D22 to D28 of the study, there was a higher (P ≤ 0.05)
A. marginale
parasitemia in animals of T02 than in those of T01. Animals of T01 required one enrofloxacin treatment to decrease
A. marginale
parasitemia, while those from T02 needed five treatments. From D5 to D37 of study, the mean values of PCV for calves from T02 were lower (P ≤ 0.05) than that for calves from T01. In conclusion, bovines co-infected
T. vivax
needed four more treatments with enrofloxacin to reduce
A. marginale
parasitemia and keep PCV values within reference standards.
Rhipicephalus microplus is the most significant tick of livestock and its control is particularly challenging due to its resistance to commercial acaricides. Pasture rotation is considered a ...management strategy that could help control R. microplus, however, the literature only contemplates mathematical models and little is known about the effects of this practice in the field. The objective of this work was to determine whether pasture rotation is an efficient method for controlling R. microplus. Two different experiments were performed that involved groups of continuous and rotational grazing bovines. Female ticks measuring 4.5–8.0 mm were counted on animals while larvae in pasture were counted using the flannel drag technique. Treatment for infested bovines was applied when the average group tick count was ≥30 females. The results showed that rotational grazing (with 20-day periods of rest) had a higher tick count on-host than continuous grazing (P < 0.05) and additional bovine treatment was needed. Sixty and 105 days were needed to re-infest and disinfest pasture of R. microplus larvae, respectively. The first treatment of bovines occurred 91 days after the animals were placed in a closed area. The results indicate that rotational grazing is not an efficient way to control R. microplus.
•Pasture rotation did not decrease R. microplus parasitism on-host and need further treatment•Took 105 days to disinfest the pasture with tick larvae after bovines leaved the area•Took 60 days re-infested a closed area with tick larvae after bovine entrance there
It was investigated how many cattle become infected with Trypanosoma vivax by subcutaneous (SC), intramuscular (IM) and intravenous (IV) routes, using the same syringe and needle from an animal with ...acute T. vivax infection. Besides, the T. vivax viability in 109 injectable veterinary drugs (antibiotics, antiparasitics, reproductive hormones, vitamin complex and derivatives, vaccines, anaesthetics, anti-inflammatory/antipyretics, antitoxics). In the field assay, four groups were performed: T01, T02 and T03 animals that received saline solution with the same syringe and needle contaminated with T. vivax via SC, IM and IV routes, respectively, and T04 control animals that received only saline solution with the same syringe and needle IV. In the laboratory, drugs had their pH measured and T. vivax viability verified. The number of cattle infected with T. vivax via SC (3/20) was lower (P ≤ 0.05) compared to via IM (9/20), which was lower (P ≤ 0.05) compared to IV (15/20). The solution pH did not influence T. vivax viability. In 44% (48/109) of the products, T. vivax remained viable regardless of time, stooding out that in 100% of oxytocins the protozoan was verified, at some evaluation times. The mean of T. vivax quantified in foot-and-mouth and brucellosis vaccines and in doramectin-based products were higher (P ≤ 0.05) than found in blood + saline solution.
The present study aimed to evaluate biological parameters of
Rhipicephalus microplus
in the non-parasitic phase in both field and laboratory conditions. It also aimed to assess correlations between ...duration (in days) of these parameters and climatic variables (humidity, rainfall, and soil temperature) and to estimate the annual number of generations of
R. microplus
in a tropical region. The non-parasitic phase of
R. microplus
in field and laboratory conditions was evaluated throughout the course of two years. A pasture was infested with engorged female of
R. microplus
, and biological parameters, including female pre-oviposition, female oviposition, egg mass incubation, larval pre-hatching phase, larval maturation, and larval longevity, were evaluated concomitantly with the collection of data on climatic conditions. The same parameters were also evaluated in a climatized chamber in the laboratory. The total duration of the non-parasitic phase in the field was longer in the dry season (1st and 4th life-cycle repetitions) than in the rainy season (2nd, 3rd, and 5th repetitions). Tick biological parameters for the non-parasitic phase in the laboratory were similar to those obtained in the field during the rainy season. The evaluated biological parameters were influenced mainly by environmental and ground-level temperatures, which modified egg mass incubation, larval pre-hatching, and larval longevity periods and, consequently, the total duration of the non-parasitic phase of the tick. The annual number of generations for the tick was estimated at five per year, which is alarming because it represents an increase, and so new studies into strategic control are needed.
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