Foot and Mouth Disease in India
Livestock is an important sub-sector of Indian agriculture contributing 25% of the output of the agricultural sector. The contribution of livestock sector to the total GDP during 2018-19 was about 5.1%. India has a total livestock population of 535.78 million and poultry population of 851.81 million. The country ranks first with respect to buffaloes, second in cattle and goats, third in sheep and fifth in poultry production in the world. Internationally, India ranks first in production of milk. India produced 1,76,347.35 thousand tonnes of milk, 7,655.61 thousand tonnes of meat and 41,462.72 thousand kg wool in the year 2017-18. The success of livestock industry depends on the health of the livestock with increase in productivity and any compromise on health ground will shatter the hope of livestock sector. Various programmes launched by government of India and other organizations to improve breeding, feeding and health status have brought positive change in production and productivity in the country but susceptibility to various diseases has also increased. Animal diseases pose significant threat to livestock sector throughout the world, both from the standpoint of economic impacts of diseases themselves and the measures taken to mitigate the risk of disease introduction or spread. Out of the four pillars of animal husbandry i.e., breeding, feeding, management and disease control, the disease control is the most critical factor to make the livestock sector economically viable. Economic losses caused by the diseases are mainly due to loss in milk production, reduction in working ability of work animals, reduction in the body weight leading to reduced yield of meat. In addition to this, in some diseases the milk and milk products, meat and hide and skin are not accepted by countries free from the diseases, causing reduction in export potential of livestock industry.
Foot and Mouth Disease – A Major Threat to Livestock Sector————
The prevalence and outbreaks (FMD) notably List A OIE diseases like Foot & Mouth Disease, are one of the primary hurdles to reaching the sector’s desired growth rates. It has an impact on India’s domestic cattle population, resulting in significant financial losses for animal owners. Due to its highly infectious nature, capacity to induce persistent infections, and long-term consequences on the condition and productivity of the numerous animal species it affects, it is the most commercially important veterinary disease. In mature livestock, it is usually not deadly, although it increases the risk of spontaneous abortion in pregnant animals and death in young animals. FMD has been deemed as one of the top priority illness in India for control and elimination. This acute, highly contagious disease affects all cloven-footed mammals and is characterized by fever and vesicular eruptions in the buccal cavity, teats, and feet. Aphthous fever, infectious aptha, panzootic aptha, and other terms have been used to describe this condition.
Aetiology
FMD is caused by an aphthovirus of the family Picornaviridae. It is a positive sense single stranded RNA virus. There are seven strains (A, O, C, SAT1, SAT2, SAT3 and Asia1) which are endemic in different countries worldwide. Serotypes O & A originated in France, C in Germany, SAT 1, SAT 2, SAT 3 in South African Territories and Asia 1 in Pakistan. In South East Asia, serotype O is most prevalent, and C is least (1). Type C has been absent in India from 1997.
Epidemiology
Occurrence
FMD is found throughout Asia, as well as most of Africa and the Middle East. The majority of countries in Latin America use zoning and are recognized as FMDfree, either with or without vaccination. FMD is currently absent in Australia, New Zealand, Indonesia, Central and North America, and continental Western Europe. FMD, on the other hand, is a transboundary animal disease that can appear at any time in a normally free area. The presence of FMDV infection is endemic in India, dating back to 1864, and it has since been documented from many different sections of the country. In the country’s livestock population, only three FMDV serotypes (O, A, and Asia1) are currently circulating. In real-time investigations conducted from time to time, the emergence and re-emergence of different genotypes / lineages within the serotypes were seen. FMD spreads quickly from one animal to another, particularly in cool, moist areas and/or when animals are confined or housed in close quarters. The virus can persist at temperatures below 40 degrees Celsius, but it becomes inactive as the temperature rises (2).
Host Range
The most usually affected animals are cattle, buffalo, camels, sheep, goats, deer, and pigs. Over 70 species of wild artiodactyls have been confirmed to have the FMD virus, including bison, giraffes, Indian elephants, and several deer and antelope species. Buffaloes, unlike cattle, exhibit a milder version of the disease, and the wild African buffalo is thought to be the true natural host of SAT viral strains. The virus can survive in the pharyngeal tissues of recovered cattle for up to two years. Pigs and sheep could be important disease carriers. Animals in their early stages of development are more vulnerable.
Transmission and Spread
FMD virus is identified in all of an infected animal’s excretions and secretions. These animals exhale a large volume of viral aerosol, which can infect other animals via the respiratory or oral routes. The virus can be identified in milk and sperm for up to four days before an animal shows clinical signs of illness. Because they can discharge large amounts of virus in their exhaled breath, pigs are known as ‘amplifying hosts.’ FMD’s significance is linked to how easy the virus can spread through any or all of the following methods
1. Infected animals newly inducted into a herd (carrying virus in their saliva, milk, semen, etc.);
2. Contaminated pens/buildings or contaminated animal transport vehicles;
3. Contaminated materials such as hay, feed, water, milk or biologics;
4. Contaminated clothing, footwear, or equipment;
5. Virus-infected meat or other contaminated animal products (if fed to animals when raw or improperly cooked);
6. Infected aerosols (spread of virus from an infected property via air currents). Humans can contract FMD after coming into contact with diseased animals, but this is extremely uncommon. Although FMD is not considered a public health issue, there have been reports of persons developing antibodies to the virus while working in FMD vaccine laboratories. Animals that have recovered from infection can sometimes carry the virus and spread it to other animals, causing new outbreaks.
Clinical Signs
The severity of clinical indications is determined by the virus strain, the exposure dose, the animal’s age and species, and the host’s immunity. In sensitive populations, morbidity can exceed 100%. Adult animals have a low mortality rate (1–5%), whereas young calves, lambs, and piglets have a greater mortality rate (20 percent or higher). The incubation phase lasts between 2 and 14 days. Clinical indications in cattle and intensively reared pigs are more severe than in sheep and goats, and they can vary from mild to severe. Blisters (or vesicles) on the nose, tongue, or lips, inside the oral cavity, between the toes, above the hooves, on the teats, and atpressure points on the skin are the most common clinical signs. Blisters that have ruptured can cause significant lameness and a reluctance to move or feed. Blisters usually heal in 7 days (sometimes longer), although problems might occur, such as secondary bacterial infection of open blisters. Fever, sadness, hypersalivation, loss of appetite, weight loss, growth retardation, and a decrease in milk production are also common symptoms, which can last even after recovery. The milk output of chronically affected animals has been observed to be reduced by 80%. Pregnant animals may abort. If dams are infected, the health of young calves, lambs, and piglets may be jeopardized due to a shortage of milk. In young calves and sometimes in adults, a malignant form of disease develops with myocardial damage and acute heart failure. Mortality in such cases is certain. The common sequalae to FMD are mastitis, infertility, myiasis of hooves, sloughing of horny layer of hoof and skin of teat surface. Achronic syndrome of panting due to endocrine damage is seen in cattle characterized by dyspnoea, anaemia, over growth of hair and lack of heat tolerance.
Diagnosis
1.The disease may be suspected on the basis of history and clinical signs.
2. In necropsy findings the heart muscles have tiger striped appearance (tigroid heart appearance) and severe hyaline degeneration and necrosis.
3. Straw colored vesicular fluid and epithelial tissue are rich in virus and should be collected for laboratory tests.
4. Live virus can be isolated by cell culture. It will require a well-equipped laboratory. The time to report results is between 1 and 4 days.
5. Virus isolation: Inoculation of primary bovine (calf) thyroid cells or primary pig, calf and lamb kidney cells; inoculation of BHK-21 and IB-RS-2 cell lines; inoculation of 2 – 7 days old, unweaned mice.
6. Complement fixation test
7. Viral antigen is detected either by antigen capture ELISAor serotyping ELISAin a laboratory or using a pen side lateral flow device.
8. Reverse Transcription Polymerase Chain Reaction (RT-PCR)-Viral RNA can be detected by RT PCR, 1-2 days prior to the development of clinical signs. This can be either conventional RTPCR or real time RT-PCR. Results can be obtained within 4 – 5 hours.
9. Serologic tests for FMD are used to certify animals for import/export, confirm suspected cases of FMD, test efficacy of vaccination and provide evidence for absence of infection. The choice of serologic test depends on the vaccination status of the animals. Detection of antibodies to nonstructural proteins, which are expressed onlyduring virus replication, can be used to determine past or present infection with any of the 7 serotypes, whether or not the animal has been vaccinated.
Differential Diagnosis
FMD- vesicles, myocarditis and gastroenteritis 2. Vesicular exanthema – vesicles, no myocarditis and gastroenteritis 3. Vesicular stomatitis – less conspicuous vesicles, no myocarditis and gastroenteritis .
Treatment
1.Washing the affected area with mild disinfectant (2% caustic soda, 4% soda ash and 2% acetic acid). Antiseptic mouthwash with potassium permanganate lotion, 2% alum and application of boroglycerine is good for rapid healing. Foot lesions should be washed with 2% copper sulphate and fly repellent ointments should be pasted on the lesions.
2. Applying antibiotics locally.
3. Protective dressing to inflamed areas to prevent secondary infection.
4. Sulfadimidine or broad-spectrum antibiotics injections are useful to the secondary bacterial infection.
5. Use of levamisol and zinc sulphate has been found quite effective and can be used in treatment and prophylaxis of FMD in domestic animals.
6. A good systemic response is reported to the administration of flunixin meglumine.
Technoeconomic Aspects of FMD
The direct losses based on the reports indicated that average annual economic loss due to FMD was around Rs. 20000 crores. Milk production decline accounts for 80% of the overall direct loss caused by FMD (3). Saxena, R. (1994) (4) used an Indian survey to assess FMD-related losses in milk production and abortion. According to the author, India’s yearly milk losses amount to 3,508 million litres, or around 6.5 percent of the country’s total annual milk supply. The annual loss of milk in terms of value at 1990 prices was Rs. 12,520 million in lost foreign exchange and between Rs. 16,500 million and Rs. 18,730 million in lost domestic economic surplus. Saxena calculated the losses owing to decreased draught power, animal mortality, and treatment costs at Rs. 18,130 million in subsequent research. Govindraj et. al. (5) conducted a study in Kolar district, Karnataka state, India, to analyse the impact of FMD outbreaks in cattle and buffaloes on the farming community. There were 178 samples collected, including buffaloes, indigenous cattle, and crossbred cattle. Milk yield loss and distress sale accounted for 74 percent of overall loss in indigenous cattle, followed by draught power loss (10 percent), extra labour engaged for nursing FMD – affected animals (8 percent), and treatment costs (8 percent). The most significant loss in cross bred cattle was mortality (37%) followed by distress sales of sick animals (35%), milk supply loss (23%), treatment costs (3%), and extra labour for nursing the affected animals (2 percent). The important loss component in local buffaloes was mortality loss (48%), followed by milk yield loss (20%), distress sale (18%), treatment cost (8%) and extra labour engaged for nursing the affected animals (7%). In upgraded buffaloes, the mortality loss amounts to 54%, followed by milk yield loss (30%), extra labour engaged for nursing the affected animals(6%) and treatment cost (4%). Sinha et. al. (6) assessed the economic impacts of FMD from small farmers across the villages of Pune region. The loss in terms of reduced revenues and cost as extra resources used for treatment were quantified and aggregated. For estimating loss per animal, the reduced output/value was multiplied by average market price during the outbreak. The major share of the loss in case of crossbred cow and buffaloes was due to the reduction in the market value of the animal after the disease. This is because in crossbred animals, the appearance of the animal changes drastically after the illness. This was found out to be Rs. 3184.00 in crossbreed cows and Rs. 3062.50 in buffaloes, whose share was 74.31 and 81.69%, respectively out of the total loss reported per animal in sample respondents. The next major part of loss was due to the reduction in the milk yield due to the disease in both crossbred cows and buffaloes that was accounted Rs. 894.60 (20.88%) and Rs 510.00 (13.60%), respectively. The next about 5% loss was due to reduction in hide and skin values as estimated. The cost incurred for in FMD which included medicine cost, veterinary service charges, extra labour used, disinfectant and infertility costs and miscellaneous costs was Rs. 1314 per animal for crossbreds and Rs. 646 for buffalo. The total expenses due to FMD were worked out to be Rs. 5598.80 in crossbred and Rs. 4394.38 in buffaloes per animal, shows the expenses due to the disease was comparatively higher in the crossbred cow (7). It is considered one of the most economically relevant transboundary animal diseases because of its high transmissibility, impact on production and trade restrictions at local, national and international levels. In countries where the disease is endemic it can impose serious restrictions on the development of that country’s livestock industry. On a macroeconomic level it will limit the ability to export meat products to other countries; it will also cause economic losses at the level of the farm, often in low-resource contexts where those losses will have a significant impact on the farmers’ livelihoods.
Prevention and Control
The initial measures are the presence of early detection and warning systems and the implementation of effective surveillance in accordance with the guidelines detailed in the OIE Terrestrial Code. They help monitor the occurrence and prevalence of the disease and allow characterization of FMD viruses. The implemen-tation of the FMD control strategy varies from country to country and depends on the epidemiological situation of the disease: In general, it is essential for livestock owners and producers to maintain sound biosecurity practices to prevent the introduction and spread of the virus. The two main methods used by a few countries for control of FMD are vaccination and culling, sometimes in combination. In endemic areas, vaccination is the only real option, however the existing vaccines are mostly killed virus vaccines that don’t provide cross protection against other virus strains and require booster vaccinations.
Measures that are recommended at the farm level include
1.Control over people’s access to livestock and equipment
2. Controlled introduction of new animals into existing herds after quarantine periods only.
3. Regular cleaning and disinfection of livestock pens, buildings, vehicles and equipment
4. Monitoring and reporting of illness
5. Appropriate disposal of manure and deadcarcasses Contingency planning for potential outbreaks will identify the elements included in a response effort to eradicate the disease, such as
1. Humane destruction of all infected, recovered and FMD- susceptible contact animals in countries where allowed
2. Appropriate disposal of carcasses and all animal products
3. Surveillance and tracing of potentially infected or exposed livestock
4. Strict quarantine and controls on movement of livestock, equipment, vehicles
5. Thorough disinfection of premises and all infected materials (implements, vehicles, clothes, etc.)
Use of Vaccination
Vaccines are one of the very important tools in the control of FMD in India (8). Depending on the FMD situation, vaccination strategies can be designed to achieve mass coverage or be targeted to specific animal sub-populations or zones. Vaccination programmes carried out in a target population should meet several critical criteria, mainly:
1. Coverage should be at least 80 – 90% for control
2. Campaigns should be completed in the shortest possible time
3. Vaccines should be administered in the correct dose and by the correct route The vaccines used should meet OIE (9) or IP standards of potency and safety, and the strain or strains in the vaccine must antigenically match those circulating in the field. It is important to use inactivated polyvalent virus vaccines, as inactivated virus does not have the ability to multiply in vaccinated animals. The use of live virus vaccines is not acceptable due to the danger of reversion to virulence. In India, trivalent (O, A, Asia1) vaccines are in use. The vaccine should be administered as per manufacturer’s recommendations. A booster dose should be administered 1 month after 1st dose in primo – vaccinates. Revaccination is recommended every 6 months. Ring vaccination is conducted to contain an outbreak and frontier vaccination to produce a buffer area between infected and free countries. Vaccination can play a role in an effective control strategy against FMD, but the decision on whether or not to use vaccination lies with authorities. Inactivated FMDV vaccines are readily available in Indian market to prevent and control FMD (10). In spite of vaccination, outbreaks may be reported due to possible strain variations.
Tips to reduce the spread of FMD in herd during an outbreak
All cloven-footed animals in the exposed groups should be immediately slaughtered and burnt. But it is practically impossible in Indian circumstances.
The following measures are, therefore, advised to cut down the spreading of the disease—
1.Isolate and confine the animals immediately after detection. An immediate quarantine of animals within a radius of 10-15 miles is advised.
2. Containment of the infection by ringing the outbreak area with a zone of vaccinated animals is advised.
3. The inanimate objects in animal premises and the environment immediately surrounding the infected premises should be regularly disinfected with either 1-2% sodium hydroxide or formalin solution. Solution of 4% sodium carbonate that kills the virus within minutes can also be used. Sprinkling lime powder in affected animal house is recommended.
4. Vaccinate all animals kept in close contact with the affected animals.
5. Restrict movement of persons from the infected premises.
6. Do not purchase new animals for next six months.
7. Separate calves from affected mothers.
8. The symptomatic treatment should be started immediately using light KMnO4 solution and boroglycerine. An antibiotic umbrella to the animal is advised to check secondary bacterial infection.
9. Detailed characterization of virus isolates including antigenic analysis and molecular epidemiological studies are help to ensure that the virus strains incorporated in the vaccines are appropriate for controlling the strains circulating in the field.
Conclusion
Foot-and-mouth disease, an economically important viral disease of livestock that causes huge yearly losses of almost $200 billion, is being prevented and controlled in India. India has effectively eliminated Rinderpest and Polio virus in the past, and it has greatly enhanced its know-how and institutional capacities to handle a large-scale programme such as the FMD control programme. As a result of this approach, the number of FMD incidences / outbreaks reported has decreased. India has put in place a system and expertise to prevent and control FMD, with the goal of eradicating it by 2025 – 2030., but that has to be backed by the livestock owners, scientific communities, institutions, implementing agencies and all stake holders and its people.
BY-Shreya Dubey, M N Brahmbhatt, J B Nayak, Sonali Thakur and Nishant Patel Dept. of Veterinary Public Health & Epidemiology, Kamdhenu University, Anand, Gujarat.
References
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