OCCURRENCES OF LUMPY SKIN DISEASE (LSD) IN CATTLE IN DINAJPUR SADAR OF BANGLADESH

Received 17 November, 2020 Revised 23 December, 2020 Accepted 27 December, 2020 Online 12 January, 2021


INTRODUCTION
Lumpy skin disease (LSD) is an acute infectious viral disease of cattle that is mainly endemic in most of the African countries, having high morbidity and low mortality (Davies 1991). In the same way, LSD continues to circulate over the Middle East region and now is a grievous threat to the rest of Asia and Europe (Abutarbush, 2015). Currently, this disease has the significant impact on cattle farming specially in the smallscale farming where the economic losses are confronting the farmer towards the lower livelihood and discourage the farming in our country. The LSD is caused by Lumpy skin disease virus (LSDV) is a double stranded DNA virus of the genus Capripoxvirus belongs to the family Poxviridae (Babiuk et al., 2008) (Woods 1988). This virus is closely related sheeppox and goatpox viruses in the genus Capripoxvirus (OIE, 2012). Moreover, LSD has not been found in sheep and goats even when they are kept in a close contact with infected cattle (Davies, 1991). Likewise, this virus is primarily transmitted by mechanical means, including the arthropod vectors such as biting flies, mosquitoes (Aedes aegypti) (Chihota et al., 2001) and recently three tick species were suspected of the family Ixodidae, namely Rhipicephalus appendiculatus, Amblyomma hebraeum and Rhipicephalus decoloratus) (Lubinga et al., 2017). In particularly, the LSD is characterized by fever, nodules (2-5 cm in diameter) on the mucous membranes and skins, folliculitis, lesions in the respiratory and gastrointestinal tracts, and enlarged the superficial lymph nodes (Salib et al., 2011). Additionally, the morbidity of LSD ranges from 3 to 85% in different areas depends on various situations. Most commonly the morbidity is estimated at 10% in endemic areas (OIE, 2012). On the other hand, though the cattle of both sexes and all ages are sensitive to LSDV, but there is some instance to support those young animals may be more prone to the severe form of the disease (Al-Salihi, 2014). Generally, the mortality varies between 1 and 3%, but may reach up to 40% (Coetzer, 2004). However, this disease causes considerable economic losses due to emaciation, permanent damage to hides, infertility, mastitis, loss of milk production, and also mortality (Salib et al., 2011), but there was limited study on LSD in Bangladesh. Though, some of the epidemiological and pathological study carried out (Ali et al., 1990) but there is a huge gap about the proper information of it. Thereafter, an update epidemiological data is essential to control the vector followed by blocking the transmission of LSD leads to decrease prevalence in every year. Hence, this study sought to investigate the prevalence of LSD associated with herd level and some of management status of cattle in Dinajpur district of Bangladesh.

Study Period and area
The study was conducted during the period of April, 2020 to July, 2020 and the study area was different places of Dinajpur Sadar upzilla of Dinajpur is located at 25.63° north latitude and 88.65° east longitude, a district in Bangladesh situated in the northern part of Bangladesh. The spatial location of the study areas was presented in the map (Fig.1) using ArcGIS-ArcMap version 10.8 (ESRI, USA) software.

Sample size
During this study period a total of 453 sick animals suffering from different diseases in the study area were considered as sample size of the study. The data were recorded from the owner of the animal by visiting their farm. All the information of affected animals was recorded by previously formed questionnaire with close interview (Meher et al., 2018). The data on vaccination with goat pox vaccine was considered to determine the vaccination history.

Clinical examination
Close inspection was done carefully to observe the clinical signs (Meher et al., 2017) included the typical fever for three days and marked decrease in the milk production at the first stage (acute form). Moreover, others clinical signs like as nasal discharge, lacrimation, anorexia, emaciation, enlarged lymph nodes and lesions in the skin and oral mucous membranes were common in LSD which considered for clinical diagnosis (El-

Samples collection, processing and microscopic examination
Depending on the case, Skin scraping were collected from the affected area and placed in dry clean sterile test tubes. However, all the skin scrapings and nodular pus were collected processed according to the methods followed by Fantaye and Melake (2018) and sent to laboratory under the department of Pathology and Parasitiology of Hajee Mohammad Danesh Science and Technology University, Dinajpur-5200, Bangladesh for laboratory examination. After that, each skin scraping was placed to clean and dry glass slide and examined directly under light microscope for detecting the presence of mites and mosquito larvae. Consequently, the positive sample was allowed to treat with few drops of 10% KOH to detect the presence of fungus (Fantaye and Melake, 2018;Greiner, 2012). This attempt distinguished the LSD with other skin diseases.

Statistical Analysis
After collection of data, all the data were inputted in SPSS version 25.0 for statistical analysis. At first, data were subjected to Pearson's Chi-square test. Before performing the Pearson's Chi-square test all the assumption were tested and found to be fit. Additionally, Phi and Cramer'V was calculated to measure the strength of effect of the variables. In case of 2×2 contingency table the Phi and if the table is not 2×2 then Cramer'V value was considered. Among the variables, those were significant (p<0.05) in Pearson's Chisquare test, allowed for univariate and multivariate logistic regression by forward LR method. All p-value <0.05 was considered statistically significant.

RESULTS
In this study, a total of 453 cases was recorded and among them the LSD cases was confirmed of 186 which revealed that the prevalence of LSD was 41.06% in cattle. The herd level information of cattle was presented in Table 1, shows that sex, age, breed and skin lesions of cattle had significant (p<0.001) association with LSD occurrence. According to the all recorded cases the, the higher percentages of LSD positive cases was 44% in male, 68% in aged less than the 1year, 50% in local cattle, 43.1% in non-pregnant cattle and with 69% skin lesion through all over the body. Specifically, among the all LSD cases the significantly (p<0.001) highest proportion was approximately 64% in the age of less than 1 year, about 75% in local breed cattle, near to 90% in non-pregnant animal and around 44% had skin lesions all over the body (Fig. 2). The symmetry analysis indicated that the age had medium effect and the skin lesions had strong effect on the number of LSD cases expressed by the Phi= 0.473 and Cramer's V=0.537 respectively ( Table 1). As the Table 2 shows, the LSD outbreak in association with management status of cattle where deworming, vaccination, grazing pattern, use of disinfectant and fly repellent had significant (p<0.05) association to LSD among the all recorded cases. In considering the all recorded cases the highest percentages of LSD positive cases within the categorical level were no deworming of 45.7%, no vaccination of 45.4%, grazing in flock of 46.7%, never use of disinfectant of 49.4% and no fly repellent of 44.8%. In Figure 2, Among the LSD positive cases, the significantly highest proportion was about 58% in non-dewormed (p<0.05), 61% in non-vaccinated (p<0.01), 61% in flock wise grazing (p<0.01), and 75% in no use of fly repellent (p<0.001). The symmetry analysis alluded that the most of the cases had negative effect.  The binary logistic analysis of herd level information of cattle was presented in table 3, shows that the several variable on the likelihood had the impact on LSD outbreak. The univariate model contained four independent variables (Age, Breed, Skin Lesions and Pregnancy status). At the univariate level, no outbreaks of LSD tended (P=.08) to be higher in 2.5 to <5 years cattle compared with other ages' cattle. The herd level information associated with the likelihood of no LSD outbreaks included the local breed cattle (Odds ratio, OR=0.367; 95% Confidence Interval, CI: 0.244-0.553), skin lesions in abdominal regions (OR=3.098, 95% CI: 1.620-5.923), Pregnant cattle (OR=1.892, 95% CI: 1.057-3.386). Following the multivariate analysis, the skin lesions in abdominal region had four times increased odds of having no LSD outbreaks compared with skin lesion in other areas. The lower odd ratio was 0.068 with 95% CI: 0.029-0.159 in the cattle less than 1 year of age.
The univariate analysis of management factors associated with LSD outbreak indicated that the dewormed cattle are 1.493 (95% CI: 1.024-2.177) times likelihood to less LSD. Moreover, the odd ratio of vaccinated, individually grazed, regular use of disinfectant and fly repellent, among the study animal was 1.491 (95% CI: 1.020-2.180), 1.656 (95% CI: 1.133-2.421), 1.516 (95% CI: 0.952-2.414) and 1.660 (95% CI: 1.097-2.513) respectively. These odd ratios indicated that practicing of these factors minimized the LSD occurrence near to two times. At the same time the multivariate analysis indicated that the individually grazed cattle and use of disinfectant in often more likelihood to reduce the LSD with the odd ratio of 1.681(95% CI: 1.143-2.471) and 1.824 (95% CI: 1.155-2.878).

Variables
Category Level

DISCUSSION
This study revealed that the overall prevalence of LSD was 41.06% in Dinajpur of Bangladesh. But other authors reported the dissimilar prevalence of LSD such as, the authors Elhaig et al., (2017) and Ochwo et al., (2019) found 17.4% in Egypt and 8.7% in Uganda respectively. In fact, the prevalence may differ from region to region. Additionally, the prevalence of diseases also depends on some several factors. Among them, the most common in herd level which was sex, age, breed and pregnancy condition of an animal. Though our findings suggest that there was no any significant (p>0.05) influence of sex on LSD but Ochwo et al., (2019) reported that the sex of cattle had significant effect on LSD in Uganda. Interestingly, our study was in line with the findings of Elhaig et al., (2017) who found no significant association of sex on LSD occurrences. In considering the age of animals, the prevalence was higher in younger when compared to adults. This finding indicated that the very young cattle might have been malnourished with impaired cellular immunity (Hunter and Wallace, 2001). On the contrary, the low prevalence in young cattle associated with lower susceptibility to biting flies where there is less insect activity (Troyo et al., 2008). The authors Elhaig et al. (2017) and Molla et al. (2018) reported the LSD prevalence was higher in adult cattle in comparison with young. This dissimilar report to our study was probably due to variation in study place and time. Among the skin lesion produced by LSD in cattle, the appearances of nodules undergone to degenerative changes on the skin surface in the abdominal and neck regions of the body (Zeynalova et al., 2016). In our findings the highest prevalent had the skin lesion all over the body. This might be due advanced stages of the diseases because the nodule in skin exhibited a higher concentration of virus (Zeynalova et al., 2016) linked to the secondary bacterial infection which jointly aggravate the condition in progressive stage of diseases. Besides this, virus could be detected in sample from the skin lesions up to 92 days of post-infection (Tuppurainen et al., 2005). In our study, majority portion of LSD cases was non pregnant. Thought, possibility of diseases higher in pregnant animal due to nutritional deficiency, our result might have due to variation in sample size. Although the local breeds cattle are in lower risk to diseases (Kiplagat et al., 2020) but in our study the comparatively higher prevalence found in local breed cattle than the cross breed. This could be due to presence of increase number of local breed in that study area.
On the other hand, the prevalence of the disease was mostly associated with the presence of insect vectors, livestock grazing, watering points, husbandry systems, wet seasons and market conditions etc. (Tuppurainen and Oura, 2012). In our study, the prevalence was significantly higher proportion in nonvaccinated cattle which strongly agree with the findings of Kiplagat et al., (2020) who reported 88% prevalence in cattle had not vaccinated in Kenya. In fact, for controlling the LSD, sheep and goat pox virus vaccines have been widely used because the Capripox viruses have the trend to be host-specific, yet offer cross-protection with in the Capripox virus genus when vaccinations are administered (Tuppurainen et al., 2014). Moreover, that vaccinated animals able to produce antibody, specially neutralizing antibodies within the 7 days of post vaccination (Kithing and Hammond, 1992). However, another important factors is grazing pattern of cattle where our findings expressed that 61% was involved grazing in flock with higher odd ratio. This finding is in line with the Abera et al. (2019) who stated that higher prevalence (36.1%) in cattle grazed communally was statistically significant (p>0.000, OR=2.0, CI=5.58-6.94). In fact, the animal grazed in the flock, share the watering points, grazing plots and post-harvest fields would allow contact and interlacing of different herds that would likely increase the risk of manifestation (Waret-Szkuta et al., 2011). In another side of our study, the use of disinfectant implied that it mostly reduced the LSD prevalence when applied frequently. Perhaps, this result is due to the nature of disinfectant to eliminate the viral concentration and blocked the indirect transmission. Nevertheless, biting flies may act as vector for the transmission of LSD virus (Ochwo et al., 2019). In line with our findings, the use of fly repellent had the effect to decrease the prevalence of LSD, because vector control is one of the most important strategies to restrict the spread of LSD (Alemayehu et al., 2015).

CONCLUSIONS
In conclusion, the results of this study alluded that the outbreak of LSD had significant association with the sex, breed, age and pregnancy status of cattle with the skin lesions on the whole body surface. Besides this, the management status, especially the dewormed, vaccinated and individually grazed cattle of the farms that