Extension Of Infection Research Articles

Bovine Viral Diarrhea Virus within and herd prevalence on pasture-based dairy systems, in southern Chile dairy farms

Bovine Viral Diarrhea (BVD) is a ubiquitous endemic disease in most bovine populations that causes a negative economic impact on cattle production systems. However, true herd and individual prevalence in Chile have not been estimated based on statistical and epidemiological considerations and uncertainty regarding the infection's extension at animal and herd levels. In addition, the risk factors that can influence how the infection has spread among the cattle premises have not been assessed yet. Therefore, the study aimed to estimate true herd and animal prevalence of active BVDV infection in pasture-based dairy herds and to evaluate risk factors potentially associated with the status of herds and the within-herd prevalence, using a Bayesian approach.A cross-sectional study was performed over a random stratified (proportional to herd size) sample of one-hundred and fifty dairy herds selected in Chile's two leading dairy regions (Region de Los Ríos and Region de Los Lagos). We obtained 12.311 blood samples from lactating cows, but 4.998 randomly selected samples were processed due to budget constraints. For estimating BVDV Herd Prevalence (HP), a herd was considered infected if at least one positive animal to Ag-ELISA was found. In addition, a survey was completed on each farm, aiming to collect information to assess the influence of some variables over the state of the herds; both estimations were obtained using a Bayesian approach.True herd prevalence and true individual prevalence of BVDV active infection were estimated at 77 % and 3.5 % respectively, no significant differences were found between characteristics like herd size, location, vaccination, etc. Open herds and herds that mix herd categories are more likely to have higher BVDV prevalence.

Intestinal Helminths and the Influence of Environmental Factors on Cattle Infection in the Altai Mountains

The purpose of the research: comparative assessment of cattle infection with intestinal helminths in various provinces and characteristics of the relationship between abiotic and anthropogenic environmental factors with the level of infection and the number of helminths in the Altai Mountains. Materials and methods. According to the results of long-term (2010–2019) ovolarvoscopic examinations, more than 2.4 thousand heads of cattle from 7 regions of the Altai Republic characterized by extensity of infection (EI) and the number of helminth eggs in 1 g of feces (NHE/g) in animals. By correlation analysis, the association of animal EI with helminths, NHE/g and abiotic and anthropogenic environmental factors in the context of farms and regions of the Altai Mountains is shown. The following parameters are estimated: long-term average annual temperature, long-term average annual rainfall, longterm average summer temperature, long-term average summer rainfall, altitude above the sea level, population density of the host, the effect of parasiticidal treatments of animals on parasite infection. Results and discussion. It was found that animals are mostly infected with intestinal helminths in the Choy region, where the EI was 61.7% when detecting NHE/g 81.8 pcs. Minimal infection of cattle by helminths was recorded in the Kosh-Agach region – 38.8% with NHE/g of 22.9 pcs. In the whole country, EI of animals is 51.8% with an egg number of 44.1 individuals in 1 g of feces. Within the physical-geographical provinces, cattle are mostly infected in Central Altai (EI – 56.5%, NHE/g – 43.6 pcs.), to a lesser extent in Southeast Altai (EI – 38.8%, NHE/g – 22.9 pcs.). According to the results of ovoscopic examinations, it was found that the most significant factors affecting the infection of animals with intestinal helminths in farms are the long-term average annual precipitation (r = 0.60 and 0.34) and the degree of anthropogenic pressure (r = -0.52 and -0.59), in the context of districts, long-term average annual temperatures (r = 0.65 and 0.55), average annual summer rainfall (r = 0.74 and 0.65). According to larvoscopy, the most significant environmental factors affecting cattle infection are long-term average annual temperature (r = 0.62 and 0.72), long-term average annual rainfall (r = 0.76) and elevation (r = -0.71 and -0.73), in farms – the degree of anthropogenic press (r = -0.65 and -0.78).

Нематоды пищеварительной системы домашних жвачных Узбекистана

Objective of research. A study of species composition of nematodes parasitizing the digestive system of domestic ruminants in Uzbekistan, analysis of seasonal dynamics of infestation and features of the nematode fauna in plains and foothill-mountain areas. Material and methods. In the period of 2014–2015, the digestive tracts of 206 head of cattle and 878 head of small cattle from the farms of Tashkent, Syr-Darya, Dzhizak, Namangan, Kashkadarya, Surkhandarya, Navoiy and Bukhara regions as well as Karakalpakstan autonomous republic were investigated by the method of full helminthological dissection. Results and discussion. 30 nematode species were found in digestive tracts of domestic ruminants of Uzbekistan; 28 nematode species in sheep, 26 species in goats, and 22 species in cattle. The highest rates of extensity of infection (EI) and intensity of infection (II) were detected in Ostertagia ostertagi, Marshallagia marshalli, Teladorsagia circumcincta and Parabronema skrjabini. An increase of EI and II in summer and autumn period was typical for the most of the discovered nematode species. However, EI in O. ostertagi, T. circumcincta, Marshallagia spp. and P. skrjabini was relatively stable in all seasons, but II increased to autumn. 26 nematode species were registered in plains; only 3 of them with high EI and II. 28 nematode species were registered in foothill-mountain areas, 8 of them showed high rates of EI and II. 24 species of nematodes are common in both areas. The obtained results allow us to conclude that it is necessary to improve helminth control of ruminants in Uzbekistan. Alternation of pastures and regulation of grazing, as well as preventive dehelmintization should not be ignored; observe the optimal requirements for feeding and management of animals.