Recurring instances of zoonotic diseases are adding to the worries of public health experts of Kerala. As the State is waging a pitched battle to contain the spread of COVID-19, reports of Kyasanur Forest Disease (KFD) and bird flu (Avian Influenza) have come in from Wayanad and Kozhikode respectively.
While KFD claimed a life this year, it claimed two lives last year. Culling of birds in a-kilometre radius of the two poultry firms where the outbreak of bird flu was reported was the first preventive step initiated. The culling was followed by increased surveillance in a radius of 10 km. The Nipah outbreak that claimed 17 lives in 2018 literally shook the State. The disease made its presence felt last year though the State could contain it effectively. Anthrax, though sporadically reported in animals, has not emerged as a major challenge in the State. However, leptospirosis and rabies continue to be perennial concerns for public health and animal husbandry experts.
Social mobility hit
Besides snatching away precious lives, such disease outbreaks paralyse social mobility of the affected population as a large number of individuals have to be either kept under observation or quarantine. The diseases also leave a significant impact on the economy.
While a section of wildlife experts feel that the recurrence of such diseases could be checked effectively by putting in place a round-the-clock surveillance mechanism and scientific disease management protocols, those at the Animal Husbandry Department say such diseases were an inescapable reality for the State, given the sizeable forest cover.
Wetlands and waterbodies are also routes through which diseases such as bird flu are transmitted to domestic bird populations.
Diseases such as KFD are often reported in human populations living in forest fringes. Though first reported in Karnataka, the disease has made its presence felt in the contiguous Wayanad forests. After the confirmation of the disease, instructions were issued to step up vigil and health care measures in the area, including steps to control the pest population, said R. Jayachandran, Chief Disease Investigation Officer at the State Institute for Animal Diseases, Thiruvananthapuram.
Restrictions on grazing of cattle in forest fringes where deaths of monkeys have been reported, safe handling of carcasses, spraying cattle with disinfectants, and pest-control medicines have been recommended. Disinfectants and insecticides are also sprayed in a 50-metre radius of the area where the carcasses have been found, he said.
When it comes to bird flu, migratory birds are suspected to be the carriers of the disease. Though it bears a zoonotic potential , no incident has been reported in the country so far.
The pathogens carried by the visiting bird population reach the domestic avian species through the contaminated waterbodies of the State. As a large number of migratory birds reach the wetlands and waterbodies regularly, there is the high possibility of the outbreak of the disease.
The department has also been carrying out routine surveillance programmes and analysing bird droppings for possible signs of outbreak of diseases, Dr. Jayachandran said.
After the latest episode of the outbreak, according to a communication, the institute has cautioned officials in charge of the Kadalundy Bird Sanctuary to be vigilant and watch for any suspicious illness or death of migratory birds or other birds in nearby places.
No bird monitoring plan
At the same time, P.O. Nameer, Professor, Department of Wildlife Sciences of the Kerala Agriculture University, Thrissur, who chalked out a round-the-year surveillance scheme for migratory birds for the Forest Department, said the State lacked an effective bird monitoring programme.
The surveillance scheme, prepared following the 2015 outbreak of bird flu, had an elaborate list of 115 sites in Kerala frequented by migratory birds and visiting bird species. The need for identifying the ‘flyway’ of birds was highlighted in the proposal as the State lacked such a database. The Bombay Natural History Society had agreed to collaborate with the project. However, the project did not take off, he said.
There is no point in blaming the migratory birds for the outbreak of such diseases as the State could not obtain conclusive evidence to support the theory. The health hazards posed by imported pet birds need to be looked into. The hygienic conditions of poultry farms shall be ensured, he suggested.
A consortium of experts from the Department of Community Medicine of the Kerala University of Health and Allied Sciences, Wildlife Science of the Kerala Agriculture University, and the Veterinary Public Health Department of the Kerala Veterinary and Allied Science University, may be constituted to address the issues, he suggested.
A senior official of the Forest Department, while conceding that there was no proposal for the continuous monitoring of migratory birds, said the role of the department in such cases was limited to passing on information to the Department of Animal Husbandry (DAH). When unnatural deaths of birds and other wild animals are reported, the information will be passed on to the DAH, he said.
N.N. Sasi, former DAH Director, said rapid response teams should be formed in the State to address the outbreak of diseases. “There should be an epidemic chart which features the possible diseases and the time of the year when its outbreak can be expected,” he said.
Dr. Jayachandran said disease reporting had gone online in the DAH. During the latest episode of avian flu, poultry farmers at the epicentre of the disease could be located and quarantine measures initiated using the web-based application of the department.
“Kerala is prone to such diseases and cannot secure itself from such outbreaks unless necessary measures are taken to screen the animals and birds brought into the State,” he said. Strengthening of check-posts of the Animal Husbandry Department was the need of the hour, he added.
Habitat destruction
T.S. Anish, Associate Professor of Community Medicine, Government Medical College, Thiruvananthapuram, felt that destruction and shrinkage of wildlife habitats were the key factors influencing the outbreak of zoonotic diseases.
“The loss of habitats of wild animals such as bats, monkeys, and civet cats forced them to move closer to human habitations and establish new interfaces with human beings. The new interfaces also led to the spread of zoonotic diseases,” he said.
“Civet cats have almost become urban animals as their natural habitats have been wiped out. These animals are believed to be the mediators for the pathogen that caused Severe Acute Respiratory Syndrome. Bats, which lost their natural habitats, moved into human habitations. These animals are now considered as the reservoirs of Nipah and Ebola virus,” said Dr. Anish.
The changed land use patterns and absence of effective waste management systems have led to the increase in rodent population.
Rodents such as rats spread diseases such as leptospirosis. Without addressing the habitat changes and destruction of forest ecosystems, one cannot address the issue of zoonotic diseases, Dr. Anish said.
