Studies of the Outbreaks of Foot and Mouth Disease in Uttar Pradesh, India, Between 2000 and 2006
Amit Kumar Verma,
The present study provides information about the endemicity
of the disease in Uttar Pradesh, India that can help to formulate an effective
strategy for an FMD control programme. In the Uttar Pradesh state of India,
270 FMD outbreaks were reported during 2000 to 2006. From these outbreaks,
178 tongue epithelial tissues were collected. Out of 270 outbreaks, 131
were confirmed by indirect sandwich ELISA test. Of the prevalent four
serotypes, O type FMD virus accounted for the most outbreaks (50.38%),
followed by A virus type (30.53%) and Asia-1 virus type (19.08%), while
no outbreak due to type C was detected. The study shows clearly that incidences
were highest during the winter months and in the South Western semi arid
agro-climatic zone. The distribution and density of the FMD-susceptible
population in different districts of the state also played major role
in disease incidences. Due to the unrestricted movements of animals among
different livestock markets, the disease was transmitted either by direct
contact or by aerosols from infected to healthy animals.
The economy of India is dependent mainly on agriculture. Livestock
production is a vital source of providing dietary protein for the rapidly
growing human population and it is therefore important to define strategies
for controlling infectious diseases that are undermining the livestock
industry. Foot-and-mouth disease virus (FMDV) was identified by Loeffler
and Frosch (1898) as the first filtrable viral agent to cause animal disease.
It is a highly contagious virus affecting over 60 species of cloven-hoofed
domestic and wild animals (OIE, 2007). Morbidity can approach 100% (Woodbury,
1995; Salt et al., 1996; OIE, 2007), while mortality is rare in
adult animals, though it may be as high as 50% (Woodbury, 1995; OIE, 2007),
when the virus replicates in the heart muscles of younger animals (Gulbahar
et al., 2007) resulting in death. The disease is highly contagious
and known as one of the most economically devastating diseases of livestock
(James and Rushton, 2002). The recovered animals remain in poor physical
condition over long periods of time leading to sustained economic losses
for the livestock industry. The annual loss due to FMD in India is roughly
estimated at US $800 million (Bandyopadhyay, 2004). In India, foot and
mouth disease (FMD) remains-almost throughout the year the greatest and
most feared scourge of both domestic and wild cloven-hoofed animals (Chowdhury
et al., 1992; Basu et al., 1999; Bhattacharya and Pattnaik,
1999; Bhattacharya et al., 2003). The disease is characterized
by the formation of vesicles and subsequent ulceration, generally in the
mouth, feet and udder portions (Woodbury, 1995; OIE, 2007). The virus
exhibits its pathologic effect on pituitary gland, which control the metabolic
functions in the body (Alexandersen et al., 2003). A chronic panting
syndrome characterized by dyspnoea, anaemia, hair overgrowth, and lack
of heat tolerance has been reported as a sequela in cattle (Geering et
al., 1995). In cows, infection of udders and teats may progress to
mastitis that causes permanent milk loss. Among the seven distinct serotypes,
O, A, C and Asia-1 types are the causal agents for FMD outbreaks in Uttar
Pradesh, as in India more generally. Type O FMD virus (FMDV) is responsible
for the greatest number of outbreaks, followed by types A, Asia-1 and
C. Studies of the pattern of disease in the rest of the country, including
the neighboring states, showed similar prevalence of different serotypes
of the virus (Berman et al., 1990; Ahuja et al., 1996).
A high priority is now being given to control of the disease, as the export
potential of the livestock industry has been greatly reduced by trade
barriers imposed by FMD-free countries. With a total geographical area
of 238,556 km2, the Uttar Pradesh state is quite different
in terms of its geography from most of the other states of India. There
is a long international border with Nepal, along the Northern boundary
of the state, and inter-state borders with Uttarakhand, Himachal Pradesh,
Haryana, Delhi, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand and
Bihar. In terms of agro-climatic conditions, Uttar Pradesh is divided
into nine zones: the bhabhar and tarai zone, the Western plain zone, the
mid western plain zone, the south western semi-arid zone, the central
plain zone, Bundelkhand zone, North eastern plain zone, Eastern plain
zone and Vindhyan zone. The endemic pattern of FMD in Uttar Pradesh is
marked by regular fluctuations in the frequency of the disease both within
and over the years. This study attempts to analyze the outbreaks of FMD
in the Uttar Pradesh state in order to define the endemicity of its occurrence
for the 7 year period from 2000 to 2006.
MATERIALS AND METHODS
The data source for this study was the information generated and
contained in the annual reports of the All India Co-ordinated Research
Project (AICRP) for Epidemiological studies on FMD, Regional Centre, Mathura,
Uttar Pradesh, India, which comprises the official data from the Veterinary
Services. It should be noted that the analysis is based upon the reported
cases of FMD outbreaks and an indirect sandwich enzyme-linked immunosorbent
assay (ELISA), as described in the protocol given by Bhattacharya et
al. (1996), has been adopted for confirmatory diagnosis of the virus
in the samples from FMD outbreak areas.
RESULTS AND DISCUSSION
In all, 270 FMD outbreaks were recorded from different districts of Uttar Pradesh
over the 6 year period from January, 2000 to December, 2006. Out of these, 139
were based on the clinical symptoms viz., vesicles on tongue, gums and feet,
while 131 were confirmed by laboratory test (Indirect sandwich ELISA as per
the protocol given by Bhattacharya et al. (1996). The annual occurrence
of FMD outbreaks and distribution of different FMDV serotypes is shown Table
1. Among the four serotypes prevalent in India, the greatest number of incidences
were due to type O (50.38%), followed by type A (30.53%), type Asia-1 (19.08%),
while no outbreak due to a type C were recorded (Mann et al., 1998).
The monthly (mean±standard error [SE]) outbreak pattern of FMD during
this period is shown in Table 2 and Fig. 1.
The incidences of FMD outbreaks were high during winter months, while in summer
months it was low. Densities of FMD-susceptible livestock per square kilometer
in different agro-climatic zones of Uttar Pradesh are shown in Table
3. The highest numbers of outbreaks (185) were reported from the South Western
semi arid plain zone.
Distribution of different serotypes
of foot and mouth disease virus in Uttar Pradesh, 2000 to 2006
Average monthly pattern of outbreaks
of foot-and-mouth disease in Uttar Pradesh, 2000 to 2006
Average monthly foot-and-mouth
disease outbreaks in Uttar Pradesh, 2000 to 2006
Out of 270 reported outbreaks, only 178 samples could be collected. Of these
samples, FMDV could not be identified in 47 cases, probably due either to late
reporting or to the very poor quality of samples. The possibility that cases
could have been misdiagnosed on purely clinical grounds should not be ignored.
In many instances the symptoms were confusing and these may have remained undiagnosed.
In addition, many of the outbreaks occurred in villages in the interior, where
poor transport facilities meant that samples could not be dispatched with sufficient
speed to the regional centre at Mathura. The possible reason may be that samples
were either not collected at proper time of clinical manifestation of disease
or were not suitably preserved (Prasad et al., 1992). It may be estimated
that only 20 to 30% of the cases of FMD were reported, due to an inadequate
reporting system and lack of awareness among farmers. During the period of study,
it was observed that cattle suffered most from the disease, accounting for at
least 95% of the incidences throughout the state. The remaining 5% of cases
occurred primarily in buffaloes and goats. In general, the prevalence of type
O was observed higher in Uttar Pradesh. It was also observed that neither A,
nor Asia-1 was recovered during the year (1996 to 1998).
Density of foot-and-mouth disease
susceptible livestock population with number of FMD outbreaks in
different districts of Uttar Pradesh, 2000 to 2006
It may be due to the movement of animals through borders. Increase in outbreak
due to FMDV type O in country may be because of some reasons other than antigenic
variation. Although outbreaks due to isolates divergent from reference strain
had been reported in field, but the divergent virus disappear from the field
and original reference virus remains appropriate as vaccine strain (Ouldridge,
1987; Pattnaik et al., 1990).
Climate and Transmission
The incidences of FMD outbreaks were high during winter months in comparison
to summer and rainy months. During the rainy season, between June and August,
heavy rain, very high relative humidity (>90%) and heavily moist winds may inhibit
aerosol transmission of the disease. Transmission of the FMDV from one animal
to another through an aerosol pathway is one of the major routes for spread
of the disease (Donaldson, 1979; Alexandersen et al., 2003; Gloster,
2004). During this season (rainy) also, the movement and transport of animals
from one place to another is hindered in some areas by heavy rain or floods.
From October onwards, however, the number of reported outbreaks increased due
to favorable climatic conditions of dry weather and dry winds with low temperatures
and moderate RH. Such favorable climatic factors might cause more rapid propagation
of the viral disease among the susceptible animal population. In the month of
May, due to extremely hot weather (with average temperatures of 38 to 42°C),
the number of FMD outbreaks was greatly reduced.
||Map of Uttar Pradesh state showing state and international
The effect of environmental factors on the incidence of FMD had also been
considered in earlier reports (Sellers, 1971; Donaldson, 1979; Bhattacharya
et al., 1984; Chowdhury et al., 1986).
Density, Animal Movement and Transmission
During the study period the highest numbers of outbreaks (185) were reported
from the South western semi arid plain zone during this study. These regions
have moderate temperature, relatively low humidity and lower average rainfall.
These environmental parameters favored the natural spreading of the disease
among the susceptible animals of different districts. This region has a higher
number of animals- mainly cattle, including crossbred and indigenous-per square
kilometer than the other agro-climatic regions of the state. This, in conjunction
with higher rates of animal movement throughout the year, meant a large number
of animals would be exposed to the disease. River Yamuna flowing through these
districts is an important geographical barrier. Being an important source of
drinking water, it generates movement and congregation of animals. From adjacent
state of Rajasthan (Fig. 2), tens of thousands of animals,
comprising mainly cattle and sheep, enter into this belt in waves mainly through
Mathura and Agra. While moving along these routes some of the herds branch off
Northeast to enter adjacent district Aligarh. Beyond Mathura city, migratory
herds fan out to graze in adjacent villages and fields to a depth of 6-7 km
from the road; the migratory herds share water and grazing facilities with those
of enroute villages. This migration is an annual feature wherein herds start
migrating by the end of March, only to return with the onset of monsoon (June/July).
Various cattle markets in these areas attract different species of animals including
cattle, buffaloes, sheep and goats from distant areas including those of adjacent
states of Rajasthan and Haryana. These markets generate congregation and movement
of animals. Mathura being a pilgrimage city consumes milk and milk products
in considerable quantities. To meet this demand a number of dairies have been
established in and around the city where animals are frequently replaced by
input from Haryana and Punjab resulting in the frequent turnover of animal population
increasing the possibility of importing and disseminating the infection. The
north-eastern and western railways also play roles in transporting animals to
and from other states.
The animal population in the districts of the Western Plain Zone is denser;
the ratio of cattle to other animals like sheep, goats and buffaloes is
larger. This might be the probable reason for the spread of disease. However,
natural barriers like rivers, canals and nalas (streams running from canals)
separate the areas of this region. Clearly the limitations on animal movements
observed within those areas meant less chance of contact between healthy
and affected animals. Those factors might have been responsible for the
lower number of FMD cases (43) in comparison with South western semi arid
plain zone (185) during this period.
In the Bhabhar and tarai region, the number of FMD cases was small, possibly
due to the relatively low density of susceptible animals, combined with
environmental factors like maximum annual average rainfall and high relative
humidity (Brooksby, 1982).
The FMD-susceptible animal population is much less numerous and more
scattered in the Vindhyan region of Uttar Pradsh (199.16 animals
km-2) than elsewhere. Moreover, the climate of this region
to some extent inhibits the natural spread of the disease. Thus there
were fewer reported outbreaks (3 in all) from this region.
This analytical study of FMD in Uttar Pradesh offers valuable insights
for better understanding the various aspect of disease transmission as
a whole. At the same time, the study also underlines the need to give
more attention to key areas that in turn will provide information to help
formulate an effective, improved control strategy to prevent the spread
of the disease.
The authors are grateful to all the previous professors and research
workers who devoted their time to enrich the work of the All India Co-ordinated
Research Project for Epidemiological Studies on FMD, Mathura Centre, Uttar
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