Introduction

Amphistomosis or paramphistomosis is a parasitosis caused by parasites of the Paramphistomidae family, heteroxenous trematodes of cosmopolitan distribution that affect ruminants, generating acute gastroenteritis, with high morbidity and mortality rates, particularly in young animals^1-5. Immature parasites are located in the duodenum, abomasum, adults in the rumen and reticulum⁶, they can even be located in the omasum⁷. Clinical signs are expressed in a variety of ways, including fetid diarrhea, profuse diarrhea, dehydration, polydipsia, hyporexia, emaciation, anorexia, cachexia, and even death^8,9.

In the valley of Cajamarca (Peru), Calicophoron microbothrioides has been identified as the causal agent of paramphistomosis in dairy cattle¹⁰. In one of the few studies carried out and published, a prevalence of 59±5 % of a total of 1508 cattle over one year of age, from 150 cattle farms in 19 hamlets was reported, concluding that the presence of this trematode was high and as a possible emerging disease¹¹. In another study carried out in the Northern Cajamarca valley, the presence of C. microbothrioides was reported in 54.6 % of 377 dairy cows¹².

The use of chemical dewormers is the most common practice, carried out with the purpose of eliminating it, interfering in the parasite-host-environment interactions, mainly in the environment and contamination of pastures that allow the perpetuation of its biological cycle¹³.

Oxyclozanide is considered one of the anthelmintics of choice against paramphistomids⁶, However, in Cajamarca, there are few studies on the efficacy of active principles to combat this parasitosis, so the present investigation was carried out to evaluate the clinical efficacy of oxyclozanide at a single dose of 17 mg/kg live weight (BW) in Holstein Friesian cows from a cattle farm in the Cajamarca valley, naturally infected with C. microbothrioides.

Materials and methods

The present research was conducted during the months of March to April 2017, at the farm Tartar Pecuario and the Laboratorio de Parasitología Veterinaria, Facultad de Ciencias Veterinarias (LPV-FCV), both belonging to the Universidad Nacional de Cajamarca (UNC), located in the Cajamarca Valley, at an altitude of 2536 masl, with cold climate, average annual temperature 15.2 °C, annual rainfall 767.8 mm and average annual relative humidity 62.6 %¹⁴.

The cows on this farm were not dosed with any type of antiparasitic for 12 weeks prior to the start of the study. Thus, a first coproparasitological sampling was carried out on all the animals of the farm (65 cows over 3 years of age) to identify naturally infected positive animals, thus forming a group of 15 Holstein Friesian cows with a parasite load greater than 1 egg per gram of feces (EPG). The animals were kept under similar rearing and feeding conditions (grazing), and fed with Ryegrass (Lolium multiflorum) and clover (Trifolium repens). EPG obtained on day 3 pre-dose (Day 0) was taken as a control, according to the protocol indicated by Ueno & Gonçalves¹⁵.

For the calculation of the antiparasitic dose, the BW of the animals was estimated using a bovine weighing tape measure (synthetic tape for weighing zebu, Creole, dual purpose, and dairy cattle, given in kg, lb and @, in addition, it shows the animal's thoracic perimeter in cm and in). In the morning hours, after milking (6:00 to 7:00 a.m.), according to BW, oxyclozanide (Cerozanil® Oxyclozanide 15%, Biomont, Peru) was administered at a single dose of 17 mg/kg BW, orally. The identification of the cows was taken from the earrings. Using veterinary obstetric gloves (disposable polyethylene gloves, ambidextrous, non-sterile, with a length of 86 cm and a thickness of 20 - 25 μm), approximately 100 g feces were collected directly from the rectum in the early morning hours, at day 10, 20 and 30 post dosage and processed using the natural sedimentation technique¹⁶. Finally, the antiparasitic efficacy was determined using the Fecal Egg Count Reduction Count Test (FERCT) and calculation of the efficacy percentage¹⁵.

Results

Figure 1 Egg of C. microbothrioides under the microscope at 10X. Without dye (a) and with 5% parasitological Lugol (b) 

Discussion

Paramphistomes are the most important trematodes of the rumen and reticulum of ruminants¹⁷, an important cause of loss of productivity due to the neglect of livestock farmers in recent times¹⁸. In Cajamarca, C. microbothrioides could be considered emerging, as has happened in Europe with other species of paramphistomes, a progressive increase in its prevalence, reports of acute cases in ruminants^3,19,20, preceded by globalization, climatic changes, importation of infected cattle, availability of more precise diagnostic techniques, relaxation of veterinary regulations in each country, continuous deworming with ineffective anthelmintics and the adaptation of the parasite to the intermediate host^5,21-23.

The results can only be contrasted locally, with a study conducted in dairy cattle in 2012, oxyclozanide was used (a commercial product not available in the current market), at a therapeutic dose of 12 mg/kg BW, and it resulted insufficiently active during the day 8 (37.13 %) and 16 (56.54 %)²⁴. In a foreign study (Wales), oxyclozanide (18.7 mg/kg) associated with levamisole (9.4 mg/kg) significantly reduced the number of parasites in the small intestine, abomasum, and rumen reticulum in the control of immature paramphistomes in calves. With 2 doses administered 3 days apart, 100 % efficacy was obtained, with clinical improvement in affected calves²⁵. In Galicia (Spain), oxyclozanide (15 mg/kg) also gave satisfactory results in Holstein cows, with HRCT values of 97-99 % and CPCR percentages (cattle positive by coprology reduction) of 85-93 %²⁶.

The clinical efficacy obtained resulted as the only alternative in the control of this trematode (100, 98.96, and 97.92 %) since the only commercial product available in the local market is oxyclozanide. Therefore, it represents a suitable alternative because macrocyclic lactones, benzimidazoles, niclosamide, resorantel, hexachlorophene, and closantel, gave limited or no effects in the treatment against paramphistomids^25,26-29.

In addition, it is necessary to clarify that in the animals dosed with oxyclozanide, diarrhea was aggravated for a period of 48 hours. A similar situation was observed in calves treated with oxyclozanide/levamisole, with the presence of transient diarrhea²⁵.

Although the animals were not subjected to special management and feeding conditions, they were kept grazing in the same paddocks, taking for granted their possible reinfection, which was evaluated until day 30 (4 weeks), since the prepatent period of C. microbothrioides ranges from 7 to 10 weeks⁷. Therefore, it is necessary to work on integrated control systems for this parasitosis, since the search for new active principles involves years of study, prioritizing effective control methods, with measures that are adapted and include pasture and animal management, delimiting intermediate host habitats, avoiding irrigation by immersion, rotational grazing and using efficient medications that are available^9,30. One of the major sources of infection is green forages. In one study it was reported that the contamination rate of fresh forages with eggs and metacercariae was higher in dry forages, 58.77 and 26.1 %, respectively¹.

It is concluded that oxyclozanide at a single dose of 17 mg/kg BW, orally, is effective (> 97 % efficacy) in the control of C. microbothrioides in dairy cattle of the evaluated farm. The success obtained could be of interest to be implemented in a cost-effective treatment, since it provides optimal results with a single administration, in extensive cattle breeding, avoiding greater stress to the cattle and less time in its execution by the working personnel.