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| Macaca radiata |
The Western Ghats is a mountain
range that runs parallel to the western coast of the India starting near the
border of the states of Gujarat and Maharashtra and running through
Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu states ending at Kanya
Kumari, the southern tip of India. The forests in the Western Ghats are unique
in that they are some of the best representatives of non-equatorial tropical
evergreen forests. With an estimated 7,400
species of flowering plants, 139 mammal species, 508 bird species, 179
amphibian species and 288 freshwater fish species Western Ghats is one
of the eight "hottest hotspots" of biological diversity in the world.
Researchers suspect that even more unidentified species may exist in these forests.
An estimated 325 globally threatened flora, fauna, bird, amphibian, reptile and
fish species make their home in the forests of Western Ghats. I first saw the
majestic Western Ghats as a nine year old when I accompanied my father
Professor Joshua Stephen during his research visits to the forests. In the
early nineties along with my father from whom we imbibed the enthusiasm for
forest conservation, my siblings and I including my sister Sarah, a contributor on Ecoratorio, conducted
voluntary research on the biodiversity in the Western Ghats. Needless to say,
the conservation of flora and the fauna of the Western Ghats is of much interest
to me.
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| Western Ghats near Ponmudi Hills |
Wayand , a district in the north-east of Kerala state, is
bordered by the Western Ghats on the East and is part of the Nilgiri Biosphere
reserve. An estimated 885.92 sq km of Wayanad is under forest cover, but the higher altitude allows the cultivation of cash crops and spices (Wayanad is one of the biggest foreign exchange
earners of the state),which has led to
ongoing exploitation of the natural
resources, which scientists have warned could lead to environmental
crises. One such crisis has now come from a rather unsuspecting angle - Monkey fever which has reared its head in Wayanad. First, in December 2014 more than
100 monkey deaths were reported in Wayand wildlife sactuary ; this was followed by cases of Monkey Fever in
humans in Wayanad. Since January 2015 there have been 127 reported
cases including seven deaths in
humans. Most of the affected have been tribals, the indigenous people who live in the forest and mountains of Western Ghats. An outbreak on a
smaller scale has also been reported in Malapurram district of Kerala again
affecting the tribals in that area.
What is Monkey Fever?
Monkey Fever
otherwise known as Kyasanur forest disease (KFD) is caused by Kyasanur forest disease virus
(KFDV), a member of the Flaviviridae family. Other infamous members of this
family include the virus that causes yellow fever and dengue . The disease was
first identified in 1957 by Work and
Trapido , with the observation of deaths in monkeys with heavy mortality in two species of
monkeys namely the black faced langur
(Semnopithecus entellus) and the red faced bonnet monkey (Macaca radiata) followed by
high incidence of illnesses characterised by acute fever and a few
deaths among the villagers in the forested areas of Shimoga district, Karnataka
State. Subsequently the virus was
isolated from monkeys , man, and ticks from the Kyasanur forest in Karnataka,
India and hence the name.
The vector, the main hosts,
and the reservoir hosts
The vector for Monkey Fever appears to be ticks. The virus-infested
ticks seem to infest diverse areas such as forest (tropical evergreen, semi
evergreen and moist deciduous forests,) cultivated clearings and grasslands.
KFD virus has been isolated from several
species of ticks found in the
Western Ghats , however, Haemaphysalis spinigera is thought to be
the major vector . The main hosts
of Monkey fever are rats, shrews, squirrels and porcupines, but bats and
monkeys also carry the virus. Larger mammals such as goats and cows can become
infected with KFD, but current evidence does not seem to implicate transmission
of the disease though pasteurised milk. Among animals, current evidence shows
that only monkeys seem to die upon exposure to infected ticks.
Often the first clue for the prevalence of the disease in
any area is monkey deaths, a gruesome
warning that human cases could soon follow. Humans get Monkey Fever from a tick
bite or by contact with an infected animal either ill or recently dead. Human
to human transmission has not been reported so far.
Interestingly, Monkey Fever in humans seems to follow a
seasonal pattern and human cases are usually reported from November until June,
when young ticks or nymphs become active in forests. This time coincides with
the warmer months when humans venture into forests for clearing forests,
herding and for gathering firewood.
Symptoms, diagnosis of the disease, and treatment
Like many viral diseases there is an incubation period of
3-8 days with the virus, after which the
symptoms of Monkey Fever Disease manifest suddenly with fever, severe headache, severe muscle
pain, cough , diarrhoea and dehydration.
Sometimes, bleeding from nasal cavity, throat, gums, and gastrointestinal tract
may also occur. Patients often experience abnormally low blood pressure, and low blood counts.
A small fraction of patients
recovers after 1-2 weeks of symptoms without complications. However, most patients present
a biphasic illnesses pattern and begin to experience second wave of symptoms at
the beginning of the third week. These symptoms include fever and signs of
encephalitis. Confirmatory diagnosis can be made by isolation of virus from blood by cell culture methods. Sensitive techniques such as PCR can also be used in the diagnosis in the early stages of the disease. In the later stages of the disease, enzyme-linked immunosorbent (ELISA) can be sensitive in detecting the disease.
Whilst there is no specific treatment for Monkey Fever so far, rapid
and timely supportive therapy is very important for preventing complications,
hastening recovery, and for reducing
mortality. Treatment depends on the symptoms of the patient and includes hydration,
adequate nutrition, and the usual precautions for patients with other bleeding
disorders. Patients with preexisting diseases such as tuberculosis and liver
cirrhosis maybe more prone to dying. Mortality rate upon infection ranges between 3-5%.
Who is at risk?
Tribals (Indigenous people) living in forest areas who may
come across the ticks or infected and dead monkeys during food gathering in the
forest ( the reported cases in Kerala have largely been from the tribal
hamlets), people who earn a living from
working in the forest (cattle grazers, forest officials and health care workers serving the tribal areas), and hikers in the forest are potentially at
risk for infection by contact with infected ticks or infected monkeys.
Monkey fever : Another
example of human -animal conflict ?
It has been long
argued that clearing of forest area for
cultivation causes changes in tick fauna and is considered as very pertinent to outbreaks. Deforestation could also cause the reservoir
hosts to relocate into human settlements. Additionally, deforestation causes monkeys to come
to human settlements in search of food. Livestock grazing in cleared forested areas
and grasslands also cause the ticks to attach to livestock and herders which in
turn are accidentally introduced to human settlements.
Prevalence: Monkey Fever is spreading
Although Monkey Fever Disease was thought to be endemic to specific districts
in Karnataka state, as early as the
late eighties, an antibody survey indicated the possible existence of this disease
in Kerala and Tamilnadu although there were no reported human deaths or monkey deaths then. Since 2013, Monkey Fever cases has affected Wayanad
(Kerala) and Nilgiris ( Tamilnadu), which
makes it plausible that infections in these areas may have been missed earlier
due to the lack of an organized
surveillance system. The evidence of KFD virus circulation in three southern states
of India presently raises serious concerns for human health.
Whilst eliminating the disease is nearly impossible due to
the ability of the virus to hide in the reservoir hosts in the impenetrable
forests, it could be contained effectively. Here are some recommendations:
Recommendations for the management of Monkey Fever Disease
The need
for creating awareness of Monkey Fever Disease: There should be awareness programs on monkey
fever through different communication channels. Tribal settlements in Western Ghats
often do not have access to modern amenities such as TVs , radios etc. Illiteracy could also be high, therefore awareness
messages using modern modes of communication might not reach the target groups. Therefore awareness
of the disease has to be ensured through health workers visiting the areas and
communicating orally highlighting the need to avoid high risk areas, contact with
dead animals and encouraging people to seek health care promptly on being ill.
Health
care centres/mobile health clinics in
tribal areas needed: Tribal areas are notorious for having poor access to healthcare. Tribals are also the poorest
citizens. There is often lack of/ poor
transportation to nearby towns where hospitals may be located due to lack of
vehicular roads. Even upon reaching health care centres , tribals often
face discrimination and insensitivity
from health care officials. To circumvent this, tribal areas should be provide with accessible health care centres with
adequately trained health workers /doctors who could spot the disease quickly
and give the appropriate treatment. Additionally mobile health clinics could
also be employed that can bring health services to remote and isolated parts. Furthermore,
these health care centres and mobile units could also collect data for researchers who will be able to monitor , the
prevalence, spread, and changing patterns( if any) of the disease.
Vaccination
campaigns in people in the target area and beyond: Current vaccination practice uses formalin-inactivated tissue-culture vaccine
which has been the primary strategy for
controlling KFD in Karnataka . This is a seemingly a good one. However recently published studies from Karnataka shows that the currently adopted vaccination strategy has its own pitfalls. Valuable lessons
can be learned that could be used in the other states to control the disease. Firstly
the strategy in Karnataka involved mass vaccination of persons 7–65 years of age in the high risk regions . But the study
showed that persons outside this range were also infected suggesting
vaccination programmes to include persons
outside this age group . The study also showed that vaccine coverage in
villages selected for vaccination in 2013 was surprisingly low. Further, the
uptake of the vaccine was poor ( the current vaccine is multi-dosed due to the transiency of the vaccine-induced immunity ,requiring two
vaccine doses to be administered with the first booster dose of vaccine recommended
within 6–9 months after primary vaccination after which annual booster doses
are recommended for 5 years after the last confirmed case in the area) . Only
some of the vaccinated persons took the full dose. The study showed that
effectiveness for persons taking full
dose was 82.9%, two doses ( 62.4%)
compared to non-vaccinated individuals. The study also indicated that targeting vaccination to areas
within a 5-km radius of reported KFD activity may not be effective in
preventing KFDV transmission as there have been
occurrence of cases in areas >5 km away from vaccinated villages.
In a nutshell, increased vaccine coverage is needed with respect to age as well as area (It has to extend beyond the ages of 7-65 years and has to extend to all persons- pending adequate medical advice for use in pediatric and elderly persons in the target area, and has to extend beyond the current limit of 5 km radius
Although cumbersome, full doses of current vaccine might be the best option currently available until better vaccines are available
There is a need for
production of newer vaccines that accounts for drifts and diversity of current strain,
and that which does not require periodic boosters. It is believed that such a
vaccine would lead to increased
effectiveness and increased uptake.
Carcasses of infected dead animals to be disposed appropriately: Forest officials
should be trained adequately in following appropriate biosafety procedures
while handling infected animals and should dispose carcasses appropriately and
expediently. They should also be trained in decontaminating surrounding areas
where infected and dead monkeys are found.
Initiating
Monkey Fever Surveillance Units: There should be active surveillance for
Monkey Fever by instituting Monkey Fever Surveillance Units. Not only target areas, but also regions
outside should be tested in a systematic manner for virus positivity in ticks far in advance of the peak season. This is indispensable
for preventing disease emergence in new
areas. In addition, disease surveillance
systems should be in place to monitor effectiveness of vaccination programmes and
for detecting any hidden niches of infection. Incidences of unusual monkey deaths
and human fever cases should be monitored by the Monkey Fever Surveillance Units
and information rapidly communicated to
forest officials and health authorities so that they can take prompt action.
Use of
Preventive clothing and Tick repellents: Persons living in forests and
those visiting forested areas should be
provided with preventive clothing and tick repellents . Tick repellents are
reported to provide significant protection against tick bites.
Cordoning
off the area : During the peak season, the target areas and areas in a wider radius should be off limits for outsiders (apart from health workers and
forest officials dressed in protective clothing) and hikers should
prevented from going to the
infected areas and also high risk areas.
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| Tourists encounter Bonnet monkeys near Ponmudi Hills |
Banning
cattle grazing: In the target areas, livestock grazing must be prohibited.
In this respect it has to be emphasized that tribals are not the culprits, as
they have no agricultural practices but only gather food in the forest.
Stop deforestation and slash-burn agricultural practices: Deforestation and slash -and -burn practices for agriculture forces the vectors from their natural habitats into human populations. Curtailing deforestation and harmful agricultural practices in the forests will prevent the spread of Monkey fever and other such diseases.
Monkey Fever Disease preparedness and response plans : Scientists have reiterated that often the official response to an outbreak is too late. By the time monkey deaths are noticed in an area, the ticks have already flooded the locality. Therefore, the best approach is to prepare ahead and to have all containment measures in place much in advance.
Increased research on Monkey Fever Disease : Increased research is needed on monkey fever especially on the drift and diversity of the virus, and efforts should be made towards producing better vaccines. There is also limited knowledge on the susceptibility and prevalence of monkey fever in other monkey species ( For example whether the critically endangered species Lion tailed macaque is susceptible to infection) . A concerted effort on understanding the natural history of the disease will enhance the efforts to curtail it.
Concluding thoughts
With the Monkey Fever Disease season seemingly coming to an end, the
authorities could easily fall into the trap of complacency and lethargy until new
Monkey fever cases hit the headlines
next year. However, the ease by which the disease is spreading should be a
warning to the authorities that it is a major perennial problem. It is not one of those rare diseases anymore. Timely
measures need to be in place to ensure that the disease does not spread any
further as this could threaten monkey survival as well as cause a major public
health crisis, which with passage of time might be too difficult to contain.
Addendum
Since publishing this post, I have been contacted by the MCVR Virology Lab , Manipal , India that the disease has now been detected in Goa state also.
References:
Mourya, D., Yadav, P., Sandhya, K., & Reddy, S. (2013). Spread of Kyasanur Forest Disease, Bandipur Tiger Reserve, India, 2012–2013 Emerging Infectious Diseases, 19 (9) DOI: 10.3201/eid1909.121884http://dx.doi.org/10.3201/eid1909.121884">10.3201/eid1909.121884
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