Epidemiological monitoring of avian influenza in the Republic of Crimea in 2019–2020

The paper presents results of avian influenza epidemiological monitoring in the Republic of Crimea in 2019–2020. The attention was focused on the study of water basins of the Azov and Black Seas, the Sivash Lagoon and freshwater lakes in the Feodosia Urban Okrug, Leninsky, Sovetsky, Nizhnegorsky, Chernomorsky and Saksky Raions to detect the avian influenza virus circulation. Examination of the above mentioned areas showed that some freshwater reservoirs became shallow and dry, and aquatic vegetation degraded. The natural biotope analysis conducted in 2019 and 2020 showed a decreased number of semiaquatic wild birds. The pathological material was sampled from semiaquatic and migratory wild birds, as well as from poultry kept in poultry farms and backyards. The collected samples were tested using real-time RT-PCR. In 2019, the AIV type A (H9) genome was detected in one fecal sample taken from wild birds near Kuchuk-Adzhigol Lake in Feodosia Urban Okrug. The AIV type A (H5) genome was detected in 2020 during laboratory testing of pathological material taken from the remains of a mute swan within the shoreline of a freshwater lake near the Ermakovo settlement of the Dzhankoysky Raion. The genetic analysis was performed in the FGBI “ARRIAH” (Vladimir), and the N8 subtype neuraminidase of the influenza virus isolate was determined. The comparative genetic analysis of 258 bp nucleic acid sequences of the AIV H gene fragment showed that the identified isolate belongs to the Asian genetic lineage of highly pathogenic AIV subtype H5 (clade 2.3.4.4) associated with the epidemic spread in Asia, Europe, the Middle East and Africa in 2016–2020.

Genetic analysis of nucleotide sequences of neuraminidase gene of highly pathogenic avian influenza A/H5N8 virus isolates recovered in the Russian Federation in 2020

Avian influenza is a highly dangerous viral disease that causes huge economic damage to poultry farming. Currently, highly virulent influenza virus with N8 neur- aminidase subtype is quite often detected in populations of domestic and wild birds in various countries of the world. The article provides data on complete nucleotide sequences of the neuraminidase gene of highly pathogenic avian influenza virus isolates recovered in the second half of 2020 from pathological material received from four regions of the Russian Federation. The conducted research showed that the subtype of the isolated virus was N8. According to the phylogenetic analysis, isolates of N8 virus belong to group 8C.4. During the phylogenetic analysis of the neuraminidase, we also took into account data on hemagglutinin classification, according to which H5N8 virus isolates belong to a widespread clade 2.3.4.4. Viruses of the clade were first registered in 2010 in China and they have been circulating up to now. The paper also provides data of a comparative analysis of nucleotide sequences of the studied isolates and the isolates from the international GenBank and GISAID databases, recovered in other countries from 2007 to 2020. During the analysis of the amino acid sequence of the studied isolates, no substitutions were found in the positions that affect resistance to neuraminidase inhibitors. The complete nucleotide sequences of the neuraminidase gene of the avian influenza virus subtype N8 (isolates A/domestic goose/OMSK/1521-1/2020, A/duck/Chelyabinsk/1207-1/2020, A/duck/Saratov/1578-2/2020, A/goose/Tatarstan/1730-2/2020) are published in the international GenBank and GISAID databases. Based on the analysis of the nucleotide sequences of the studied isolates, the article shows gradual evolution of the N8 subtype virus.

More on search for causes of sensitization to tuberculin PPD for mammals in cattle

Despite the large number of papers dealing with the description of proposed methods for bovine tuberculosis diagnosis and mechanisms of non-specific reaction development in diseased and healthy animals, various aspects require further study. Many specialists are still of the view, formulated when studying causes of pseudoallergic reactions, that the agents of actinomycosis, trematode infections etc. can cause sensitization of the animal body to tuberculin PPD for mammals. The possibility of sensitization of cattle body to Аctinomyces bovis tuberculin was studied in 240 animals identified as actinomycosis diseased among 3,473 tested animals. Only 11 (4.6%) of the total number of diseased animals were reactors to tuberculin PPD for mammals. During bacteriological tests of material from animals euthanized for diagnostic purposes (tuberculin reactors and nonreactors with a confirmed postmortem diagnosis of actinomycosis), acid-tolerant nontuberculous mycobacterium (NTM) cultures were isolated. The results of the experiment conducted in 628 cows of a dairy holding confirmed that Actinomyces bovis lacks tuberculin-associated allergenicity: actinomycosis was detected only in one of 96 (15.2%) tuberculin reactors. The conducted clinical tests with high significance level (Р < 0.005) showed that there is no association between allergic reaction to tuberculin PPD for mammals and actinomycosis infection. The obtained results are indicative of imperfections in differential diagnosis, and further studies in this field should significantly contribute to gaining a better insight into non-specific sensitization of cattle body to tuberculin.

Semi-quantitative risk assessment of peste des petits ruminants introduction with wild animals into Russian Federation

The Russian Federation was officially recognized free from peste des petitts ruminants (PPR). As far as the disease infects both domestic and wild small ruminants, it is important to identify the level of the threat associated with the wild fauna diversity in the neighboring countries, where PPR outbreaks were reported. For that reason, habitats of various disease susceptible animal species were examined. Habitats of the wild susceptible animals were mapped for further examination of the interactions between different animal species using zoological research data; PPR outbreaks in wild animals were also designated in the map thus allowing for the detection of the potential routes of the infection spread in the population and introduction to the country. Analysis of the PPR epidemic situation in the country demonstrated that the disease cases were reported in wild mountain animals (ibices and moufflons) and migratory steppe animals (gazelles and saigas). Risk of this highly contagious viral disease spread in wild small ruminants in Mongolia was reported (probability 0.77). Expert survey was carried out for the determination of possible trends and factors of the infection introduction with the wild susceptible animals, through which small ruminant epizootologists assessed the risk probability. During the survey it was determined that PPR was expected to be introduced from Mongolia (probability 0.81), and of major significance were seasonal migrations of wild animal populations. The resulted semi-quantitative parameters of the potential risk can be recommended for the arrangement and implementation of measures aimed at prevention of PPR introduction and spread in the intact domestic and wild small ruminant populations inhabiting the territory of the Russian Federation.

Techniques of blood sampling for detection of African swine fever virus in wild boar and domestic pigs in the field conditions

It is thought that due to the high virulence of the African swine fever virus its circulation in the Russian Federation is accompanied by a low seroprevalence. However taking into account a long-term ASF unfavourable situation, the introduction of the virus into the wild boar population, and the occurrence of attenuated viral variants, the significance of serological testing aimed at the detection of viral antibodies is increasing. To collect field samples of biological material from animals for molecular genetic, virological, and serological tests, filter paper, as well as swabs, can be used. The specificity and sensitivity of enzyme-linked immunosorbent assay when testing blood absorbed by filter paper are worse than those shown when testing sera, but they allow effective detection of African swine fever virus antibodies. It was demonstrated that blood absorbed on filter paper can be used for the immunoblot analysis, but the optimum performance could be achieved when the immunoperoxidase technique in combination with samples, taken by swabs was used. When comparing results of enzyme-linked immunosorbent assay performed on sera collected from domestic pigs (infected with ASFV isolates Antonovo 07/14 and Sobinka 07/15), and blood from ear veins absorbed on filter paper the sensitivity was 88.9%, specificity – 90.6%. However, the use of the immunoperoxidase technique for testing blood from swabs showed 100% coincidence with ELISA, while testing of sera with immunoperoxidase technique was superior to ELISA in sensitivity. This means blood sampling using swabs may be recommended for tests after proper validation. This technique can be especially useful for collecting data about infected wild boars because effective eradication strategies are impossible without such data.

Prospects for the use of a Bacillus subtilis metabolites-based feed additive in dairy farming

Laboratory and field experiment on use of the feed additive based on Bacillus subtilis endo- and exometabolites for the cows in different physiological periods are described in the paper. The feed additive impact on main body systems of the tested cows (n = 30), milk production parameters, growth rate of the calves (n = 18) born to the said cows were examined. The feed additive was added to the diets for the cows of test groups, 15 g per cow. The feed additive was found to have a positive effect on immunohematological and metabolic processes in postpartum cows. Neutrophils’ phagocytic activity increased by 12.5% and 14.6% in the animals of test group 1 and test group 2, respectively, as compared to that one in control animals (42.8 ± 1.9%). Neutrophil absorbency increased by 2.5 times, 3.2 times and 2.1 times in the animals of test group 1, test group 2 and control group, respectively. The proportion of T-lymphocytes in blood of animals in test group 1 and test group 2 was 44.5 and 48.9%, respectively, proportion of T-lymphocytes in blood of control animals equaled to 37.5%. Trend for increase in total protein concentration in cow sera owing to increase in albumin fraction was observed in postpartum period: it was 72.91 ± 3.45 g/l in test group 1; 75.54 ± 4.12 g/l in test group 2; 70.95 ± 4.25 g/l in control group. Average daily milk yield in cows of test group 1, test group 2 and control group for the 150 days of lactation was 24.50 ± 1.86 kg; 25.33 ± 1.45 kg and 22.75 ± 4.41 kg, respectively. Higher growth rate was reported for the calves born to the cows received the diet supplemented with the said feed additive. Heifers of test group 1 and test group 2 have reached body weight of 193.51 ± 5.76 and 195.33 ± 3.76 kg and in control group – of 187.33 ± 4.98 kg within 6 months. Feed additive based on endo- and exometabolites of Bacillus subtilis is recommended for cow diets for highly productive dairy herd creation and food-producing animal welfare maintenance.

Echinococcosis of dogs in the North Caucasian Subjects (infrastructural, epizootological and sanitary-hygienic analysis)

Based on the official statistics the situation of parasitic diseases in the Russian Federation is still quite unfavorable. The issues of soil contamination with Echinococcus granulosus eggs are understudied that’s why the objective of the research was to study canine echinococcosis which poses a threat to animal and human disease freedom in the North Caucasian countries. Helminthological tests of the guardian dog feces were performed in seven North Caucasian Subjects: the Stavropol Krai, the Karachay-Cherkessia Republic, the Kabardino-Balkaria Republic, Republic of North Ossetia −Alania, Republic of Ingushetia, the Chechen Republic, and the Republic of Dagestan. As a result, it was determined that the average frequency index of echinococcosis occurrence was 85.07%. The moderate fecal egg count in 1,400 samples was 22.73 ± 1.49 eggs per 10 grams of dog feces. The data obtained are indicative of the disease unfavourable situation in the Subjects and the zoonosis spread at the regional level. Helminthological tests of 14,000 soil samples from near-village pastures for contamination with tapeworm eggs, including Echinococcus granulosus, showed that the invasion rate in the Stavropol Krai was 65.80%, in Karachay-Cherkessia republic − 79.00%, in Kabardino-Balkaria − 82.60%, in North Ossetia − Alania − 74.65%, in Ingushetia − 88.20%, in Chechnya − 83.75%, in Dagestan − 79.85%. The results obtained testify to the high level of soil contamination with the infective eggs. It was demonstrated that there is a relationship between the distribution of viable Echinococcus granulosus eggs in pasture soils and ecological characteristics of the Subject: the largest number of viable Echinococcus granulosus eggs was observed in submountain areas, fewer eggs were observed in flatlands, and the least number of eggs – in the mountain areas. The number of eggs detected in the soil samples from pastures is indicative of the disease persistence in humans and animals. Results of the helminthological tests of 7,500 soil samples from 119 cattle-driving routes of the North Caucasus demonstrate 100% contamination with parasitic agents which poses a threat of epidemiological and epizootological situation of echinococcosis in the Subject.