- Introduction
Livestock farming is an integral part of the agricultural production system in India and plays a crucial role in the economic growth and food and nutritional security of the nation. It also contributes significantly to the socioeconomic growth of small and medium-sized farms. More over a quarter of the agricultural sector’s total output in India is generated by cattle alone. In 2010-2011, animal husbandry contributed 3.37 percent to the nation’s gross domestic product, indicating that it is the largest industry in the Indian economy. The profitability of the livestock business hinges on the continued productivity of healthy livestock. Plans for animal breeding used foreign germplasm to boost the animal’s productivity; disease resistance and animal health were of the least concern. Disease susceptibility destroyed the livestock industry’s optimism, and these problems are multifaceted. India has the largest cattle population in the world, despite its milk and meat production being 20-60% lower than the global average.
In addition to the low productivity of Indian animals, livestock illnesses, decreasing resistance to infections, and a lack of an efficient disease control strategy contributed to the production loss. Four of the top 10 diseases affecting livestock are caused by parasites. Parasitic diseases are a global problem not just in terms of health difficulties, but also in terms of economic status. Ticks and tick-borne diseases (TTBDs) rank fourth among the most prevalent livestock infections, and tick-borne diseases are considered the most significant arthropod-borne diseases of cattle, people, and companion animals. The transmission of Lumpy skin disease (LSD) by ticks increases the importance of tick control. The disease can quickly spread hundreds of kilometers from the initial outbreak sites. These intrusions have reignited interest in LSD. New research on the disease’s epidemiology, transmission, and risk factors has begun.
LSDV appears to travel long distances via infected animals, while seasonal patterns indicate that arthropod-borne transmission is responsible for short-distance spread. Understanding how LSDV spreads will enable more effective containment and eradication strategies. The disease is most likely transmitted mechanically by vectors, but there is insufficient data to support or refute this. The most likely LSDV carriers are stable flies, mosquitoes, and hard ticks (Rhipicephalus and Amblyomma species).
2. Economic Impact
Ticks and Tick-Borne diseases (TTBD) affect 80% of the world’s cattle population, and their prevalence is widespread, particularly in tropical and subtropical countries, resulting in production losses. Vector-borne diseases have a direct or indirect impact on the growth of the livestock industry, which is critical to rural India. They provide income to farmers and ensure food supply and income during agricultural hiatus. Ticks cause a variety of losses and directly attach to the host, causing toxins to be injected, blood loss, general stress, hide damage and irritation, and a decrease in productivity in terms of milk, meat, and so on. It indirectly suppresses immune function and spreads several pathogens. The annual global costs of TTBDs in cattle ranged from $13.9 billion to $18.7 billion. Losses from cattle ticks [Boophilus (Rhipicephalus) microplus (B. microplus) (R. microplus)] were estimated to be US$ 62 million in Australia alone, and around US$ 2 billion in Brazil.
Tick-borne diseases are regarded as the most serious problems in animal production in Africa. The annual economic losses in India due to TTBDs in animals were calculated to be US$ 498.7 million. Accurately estimating losses due to TTBDs is difficult, but they have a significant impact on farm income. TTBDs have a negative impact on dairy cows and reduce milk yield. When crossbred Holstein-Zebu cows were infested with an average of 105 ticks, milk yield was reduced by 23% per day. Loss of about 14 percent of income from milk has a significant impact on livestock-dependent systems. Furthermore, the direct impact of tick infestation on the meat and hide industry is much greater.
According to one estimate, animals with an average of 40 ticks a day could lose up to 20 kg annually and have a 20%-30% decrease in the value of their hides. Bovine tropical theileriosis (T. annulata) is caused by the protozoan parasite Theileria annulata (T. annulata) and is transmitted worldwide by tick species of the genus Hyalomma, putting approximately 250 million cattle at risk of this important protozoan disease. Worldwide and in India, the estimated loss due to T. annulata and tick fear was US$ 384.3 million and US$ 57.2 million, respectively. Despite routine vaccination, an outbreak of Kyasanur forest disease (KFD), a Haemaphysalis tick-borne infection, occurred in Karnataka, India, in 2012, indicating the need for strategic tick vector control.
3. Lumpy skin disease (LSD)
The ability of a virus to resist histolysis in tick tissues and the sensitivity of tick cells to virus infection are both necessary for a virus’ survival in tick vectors. When a single tick feeds multiple times and switches hosts in between feedings, mechanical transmission of the virus by ticks is possible, just like with insect vectors. The biology of the tick is intricate and differs across the various types of ticks. Nymphs, larvae, and adult three-host female ticks typically only feed on a host once before detaching and dropping off. The subsequent feeding takes place on a different host and in the subsequent life-cycle stage. While searching for females suitable for mating, mature males of numerous common hard (ixodid) tick species eat multiple tiny blood meals. They either do so on a single host or, if cattle come in close touch with each other, they can quickly and readily switch hosts. Females may also feed on many hosts under the right conditions, such as when the host dies or when intense host grooming pauses the feeding early on.
Experimental evidence of mechanical transmission of the LSDV from infected to uninfected hosts has been found in the male tick species Rhipicephalus appendiculatus and Amblyomma hebraeum. After feeding on infected cattle, tick saliva has been shown to contain LSDV and transstadial transmission of the virus has also been documented. It appears that tick moulting lowers viral titers. Immunohistochemical techniques have shown shown the presence of the LSD virus antigen in tick salivary glands, hemocytes, synganglia, ovaries, testes, fat bodies, and midgut. Rhipicephalus decoloratus is a one-host tick, with all three stages of its lifecycle occurring on a single host. Females feeding on infected cattle were able to transmit LSDV via their eggs to the next generation of larvae, which were able to infect naive cattle. LSDV is extremely stable, and this may constitute mechanical transmission; however, the precise transmission mechanism requires further investigation.
Likewise, Hyalomma truncatum ticks transmit the Crimean-Congo hemorrhagic fever virus sexually. During periods of interrupted feeding on the skin of an infected animal, the mouthparts of the male become contaminated with the virus. Since the male places its semen sack into the female’s genital openings with its mouthparts during copulation, it also contaminates the female. In addition, communal grazing practices that allow cattle to share pastures with other herds and/or wild ruminants are likely to facilitate the tick-borne transmission of LSDV.
Despite evidence for vector-borne transmission, outbreaks can occur in the apparent absence of vectors, demonstrating that vector-borne transmission is not the only mode of LSDV transmission. Occasional reports of the direct transmission of LSDV indicate that no season should be regarded as absolutely safe in regards to LSD.
It may be overly optimistic to assume that identifying the principal vector species would eliminate the need for vaccines, but it would aid in reducing disease prevalence. Veterinary authorities would be able to develop more effective, science-based containment and prevention strategies against LSDV if they had a better understanding of the feeding habits and preferences of local blood-feeding and biting vectors, the survival of the infectious virus in those vectors, and the capacity of local arthropod species to act as mechanical vectors.
Further research is required to investigate the role of vector saliva, the length of time mechanical vectors remain infectious, the survival time of LSDV in their mouthparts or salivary glands, and the number of insects required for infection transmission.
4. Holistic approach of tick control
The benefits and drawbacks of particular technical approaches are the foundation of tick control programmes. If used properly, chemical acaricides are effective and economical, but inappropriate application can result in chemical resistance and chemical residues in food, both of which are problems for public health. Cost, effectiveness, production, application, and stability are significant obstacles in biological control approaches. The ineffectiveness of the present anti-tick vaccines could stand alone as a question. Therefore, there isn’t currently a single, perfect, and economical method for the control of ticks.
In order to manage the population of tick integrated control is the methodical application of two or more technologies in a way that is both economical and environmentally friendly. TickGARD, a tick vaccination, was first introduced in Australia along with the short-term use of acaricides as part of an IPM package. The level of parasite control it provided was adequate. In Mexico and Cuba, more trials of a similar nature were conducted. It decreased the possibility of chemical resistance in addition to reducing the use of chemicals. Therefore, in order to reduce tick populations, it is vital to investigate the potential pairing of tick control tactics with other existing options in a given area.
5. Conclusion
Four of the top ten animal diseases are parasitic in nature. Parasitic diseases pose a threat to global health and the economy. Ticks and tick-borne diseases are the fourth most common livestock infection and the most serious arthropod-borne diseases affecting cattle, humans, and pets. Lumpy Skin Disease is transmitted by ticks. Disease can spread hundreds of kilometres from its source. Because of these intruders, LSD is once again en vogue. Epidemiology, transmission, and risk factors are being researched. Seasonal patterns suggest that LSDV is transmitted by arthropods. Knowing how LSDV spreads aids in its containment and eradication. Inadequate data confirm or refute vector-borne disease transmission. LSDV is carried by hard ticks, stable flies, and mosquitoes (Rhipicephalus and Amblyomma species). Outbreaks can occur in the absence of vectors, demonstrating that vector-borne transmission is not the only mode. Direct LSDV transmission demonstrates that no season is LSD-free. The identification of the main vector species may help to reduce disease prevalence. If veterinary authorities understood the feeding habits and preferences of local blood-feeding and biting vectors, the virus’s survival in those vectors, and the ability of local arthropod species to act as mechanical vectors, they could develop more effective, science-based containment and prevention strategies against LSDV.
Authors:
Vivek Agrawal*, Mukesh Shakya, Ashok Patil, A. K. Jayraw, G.P. Jatav and Nirmala Jamara
*Associate Professor Email: dragrawalin 76@gmail.com
Department of Veterinary Parasitology College of Veterinary Science and A.H., Mhow-453446
