Disease alerts and forecasting of zoonotic diseases : an overview

Epidemiologists are adopting new techniques by the use of Geographical Information System (GIS) to study a variety of animal and zoonotic diseases. Associations between satellite-derived environmental variables such as temperature, humidity, land cover type and vector density is used for disease prediction. Early warning systems rapidly detect the introduction or sudden increase in incidence of any disease of livestock which has the potential to develop into epidemic proportions and/or cause serious socioeconomic consequences or public health concerns. Early warning activities, mainly based on disease surveillance, reporting, and epidemiological analysis, are supported by information systems that enable integration, analysis and sharing of animal health data combined with relevant layers of information such as socioeconomic, production and climatic data. The convergence of factors such as the availability of multi-temporal satellite data and georeferenced epidemiological data, collaboration between scientists, biologists and the availability of sophisticated, statistical GIS creates a fertile research environment. In this paper, we review the Global Early Warning System (GLEWS) that formally brings together human and veterinary public health systems and application of environmental data for study of diseases like avian influenza and Rift valley fever which offers the capability to demonstrate vector-environment relationships and potentially forecast the risk of disease outbreaks or epidemics. An emphasis is also given on components of early warning system and its use for forecasting of animal and zoonotic diseases in India.


Introduction
treatment center; such centers are therefore only effective for detection and mitigation after a person has The ability to detect outbreaks early is important been infected.On the other hand, active disease to minimize morbidity and mortality through timely surveillance, which involves ''searching'' for evidence implementation of disease prevention and control of disease proactively through routine and continuous measures.The World Trade Center and Anthrax monitoring in endemic areas, could help to prevent an terrorist attacks in 2001 [1] as well as the recent West outbreak, or slow the rate of transmission at an earlier Nile virus and SARS outbreaks, have motivated many stage of an epidemic [9,10].The National Oceanic and public health authorities to develop early disease Atmospheric Administration (NOAA) operate a series outbreak detection systems using non-diagnostic of weather satellites that collect operational data for information, often derived from electronic data weather forecasting and climate prediction.Besides collected for other purposes [2,3].Emerging infectious NASA and NOAA, several European Union countries, diseases pose a growing threat to human population.
Japan, Canada and India have remote sensing satellites Climatic changes like warmer temperatures and altered that provide global observations to predict occurrence rainfall patterns are likely to increase the burden of of disease [11,12,13].The use of GIS to map vector vector-borne diseases resulting into emergence of species distribution and disease risks has evolved zoonotic diseases, too.Many of the world's epidemics considerably during the past two decades [14].The are known to be highly sensitive to changes in climate objectives of this review are to summarize and short-term fluctuations in the weather [4,5,6].
developments in the application of disease surveillance "Forecasting" is the monitoring of specific risk system for studying animal and zoonotic disease parameters helping to predict situations that could lead pathogen biology and to identify opportunities for to the occurrence of a given disease and its subsequent future research on forecasting of diseases.spread.The forecasting of disease helps to predict the course of disease, warn health care workers and adopt Objectives of forecasting [7,8] control measures to prevent disease outbreaks [7,8].
The objectives employed for forecasting of the Passive disease surveillance involves voluntary diseases include: reporting by people who are ill enough to go to a 1.To study modes of transmission and to understand how to prevent spread of epidemic diseases 2. To monitor the effectiveness of disease control campaigns 3. Emergency preparedness & disease management historical acronym OIE.This organization has set up an strategies animal health information search and verification 4. To demonstrate knowledge about the epidemi-system for the notification of emerging and reemerging ology of diseases diseases that have not yet been officially notified to the 5.To study disease importance from a public health OIE.The framework was designed to empower point of view countries and regional alliances in the fight against Advances in disease surveillance systems, epide-.Emergency miological modelling combined with information funds are rapidly mobilized for sending experts from technology have generated the expectation that early OIE Reference Laboratories to assess the warning systems are not only feasible but necessary epidemiological situation in a country and define the tools to combat the re-emergence and spread of actions required [19,20].infectious diseases [8].
World Animal Health Information Database (WAHID) Interface provides access to all data held What is early warning?within OIE's new World Animal Health Information Early Warning is the provision of timely and System (WAHIS).It replaces and significantly extends effective response through the recognized institutions the former web interface named Handistatus II System.that allows individuals exposed to hazards to take A comprehensive range of information is available actions to avoid or reduce risk and prepare for an from immediate notifications and follow-up reports effective response.[15].Early Warning and Response submitted by Country/Territory Members notifying (EWS) is based on the concept of dealing with a disease exceptional epidemiological events current in their epidemic in its early stages.From a public health territory.perspective, early warning of outbreaks with a known zoonotic potential of disease will enable control measures that can reduce human morbidity and mortality rates.The main uses of early warning system Food and Agriculture Organisation: FAO was established include education as an aid to understanding the crucial th on 16 October 1945, Canada then transferred to Rome, elements involved in early detection and response to Italy.environmental threats [15,16].
FAO, through its special EMPRES Early warning initiatives priority programme established in 1994, developed an early warning and response system [20].EMPRES Several initiatives, at national and regional levels Global Animal Disease Information System have already been developed in the field of early (EMPRES-i) is a web-based application that has been warning.At the international level FAO, OIE and designed to support veterinary services by facilitating WHO have each developed early warning and regional and global disease information.Timely and Response Systems that systematically collect, verify, reliable disease information enhances early warning analyze and respond to information from a wide variety and response to transboundary animal diseases (TADs) of sources, including unofficial media reports and including emergent zoonoses, and supports their informal networks [17,18].
progressive control and elimination.EMPRES-i aims

International organizations and their initiative
to clarify disease events worldwide that FAO receives role in development of early warning system from different sources: country or regional project reports, A six-monthly reporting by member country on the absence or presence and evolution of diseases listed by the OIE and information of epidemiological significance to other countries [21].
Achieving food security for all is the main goal at the heart of FAO.

Figure-1.
Early and late detection of disease and opportunity to control [15] but also unofficial sources of information [22].A major Well defined GLEWS are available for highly thrust of the EMPRES activity for early warning and pathogenic avian influenza (HPAI), Rift Valley fever (RVF) and other vector borne diseases and for rest of early response has been the development of softwares the diseases GLEWS is under development [29,30].

such as Transboundary Animal Disease Information
The GLEWS Management Committee (GMC) is System (TAD info), Transboundary Animal Diseases responsible for supervising the implementation of the Simulator (TAD simulator) and Good Emergency GLEWS agreement, the strategic plan and provides Management Practice (GEMP) [20,22].
general oversight of GLEWS.The GLEWS Manage-World Health Organisation: WHO was established on ment Committee guides and decides on the different th 7 April 1948, located at Geneva, Switzerland, tasks to be accomplished by the GLEWS Task Force concerned with international public health.WHO which is co-chaired by FAO, OIE and WHO [18].offers assistance to affected countries in the form of After being notified a rumor, suspicion or forecast technical advice, supplies and by mounting coordinated regarding a disease outbreak the information gathered international investigations [23].The Global Outbreak through the respective tracking and verification channels Alert and Response Network (GOARN) is building on of each organization will be fed into a GLEWS new and existing partnerships of national and electronic platform information will be further analyzed, international institutions and networks, to deal with the monitored and/or sent out as Early Warning Messages.global threats of epidemic-prone and emerging diseases Specific analysis and modeling of trends will be carried in humans and to prepare for rapid deployment and out utilizing selected OIE and FAO collaborating coordination of international resources in response to centers, OIE and FAO laboratories and WHO collaboan outbreak of international importance [23,24].rating centers.A GLEWS Emergency Response will GOARN aims at ensuring appropriate technical only be necessary, if there is clear indication for a joint support to affected human populations quickly, onsite assessment or intervention mission [23,29].assessing risks of rapidly emerging epidemic disease Aims of GLEWS [18,23,28]: threats and sustaining containment and control of 1. Better international preparedness and rapid outbreaks by contributing to national outbreak containment preparedness [24,25].WHO has developed a compre-2.Improve detection of exceptional epidemiolohensive "Event Management System" to manage gical events at country level critical information about outbreaks and ensure accurate 3. Increase timeline and sensitivity of alerts and and timely communications between key international improve national surveillance and monitoring public health professionals, including WHO Regional systems Offices, Country Offices, collaborating centers and 4. Improve transparency among countries and partners in the Global Outbreak Alert and Response compliance with reporting to OIE Network.This system generates a dynamic picture of 5. Improve field animal health information quality Alert and Response Operations and provides information and provide technical support for action in a systematic way to enable both WHO and 6.Strengthening the network between veterinary & the Global Outbreak Alert and Response Network to medical laboratories prepare better, respond faster, and manage resources 7. Provide rapid, efficient and coordinated assistance more effectively.The WHO event management system to the affected countries.is being further strength-ened to support alert and response GLEWS joint risk analysis for emergent zoonotic operational aspects of the revised International Health diseases: Risk analysis is essential to assess and Regulations [26,27].
provide options to mitigate risks associated with the Global early warning and response system emergence or spread of animal pathogens at the animal/human/ecosystem interface.Risk analysis is one of the core areas that have been recently high-GLEWS is a joint system that builds on added lighted for increased collaboration between FAO, OIE value of combining and coordinating the alert, response and WHO to address emergence of pathogens, in particular mechanisms developed by OIE, FAO and WHO [18].
on emergent zoonotic pathogens [26].The GLEWS assists in prediction, prevention and Joint risk assessment as planned will initially be control of animal disease threats, including zoonoses performed in specific regions for priority zoonotic through sharing of information, epidemiological diseases, such as CCHF, RVF, H5N1 HPAI, Rabies and analysis and joint field missions to assess and control Brucellosis.In this framework, risk analysis and mapping the outbreak, whenever needed.The GLEWS initiative methodologies will be developed and validated using started with the voluntary participation of represendata available on reported outbreaks, surveillance tatives of FAO, OIE and WHO, who share the common activities carried out by countries and combining this objective to enhance the early warning and response information with other datasets including land use, capacity for the benefit of the international community.

Mutual benefit through collaboration has been
Risk mapping tools are essential to enhance accuracy identified throughout the Early Warning and Response and sensitivity of early warning activities.Early process [28,29].warning messages will be made available to the EMPRES I linked with GIS to provide international community to serve effective response visual representation of disease outbreak and to purposes and aid targeting disease surveillance and understand epidemiological factors responsible for control activities at the animal-human-ecosystem TADs emergence and spread [35,36].interface [26,27,28].
These examples show the importance of GIS to identify spatial or spatiotemporal patterns that can be GLEWS is supported by the following Regional/ used in developing more rigorous causal hypothesis National Networks: [32,33] tests.In conclusion, the ultimate goal of early warning 1. FAO (191 Member Nations) systems is to make information and risk-assessment 2. WHO (194 Member States) outcomes available to all relevant stakeholders and to 3. OIE (178 Member Countries) provide the opportunity for timely reaction in the most 4. Regional Organizations: EC, SADC, ASEAN, cost-effective manner [10,36].CAN 5. International Reference Laboratories GLEWS approach for Vector borne diseases; Rift

National Authorities
Valley Fever (RVF): In parts of East Africa known to be 7. Unofficial surveillance programs (PROMED, prone to RVF epidemics, remotely-sensed rainfall and GPHIN) vegetation measurements have been integrated into 8. Laboratory and Epidemiological networks regional and global early warning systems and are used 9.Other partners to predict RVF before it reaches epidemic proportions.
The ultimate goal of such systems is to safeguard GLEWS approach for Highly Pathogenic Avian sustained livestock production and have developing Influenza (HPAI): In the aftermath of the avian countries participate legitimately in local, regional and influenza (AI) crisis triggered by the spread of the international trade [13,35,37].highly pathogenic avian influenza H5N1 (HPAI Epidemics of RVF have occurred in southern and H5N1), the world has been on alert to curb the spread of eastern Africa at irregular intervals.These epidemics the disease and to mitigate the risk of a potential human have been associated with above average rainfall after pandemic [10,34].
a period of drought and the presence of susceptible The FAO Early Warning System for worldwide exotic breeds of livestock [13,35].Data sets used in monitoring of avian influenza highlights the potential these predictions include satellite vegetation index and for better integration and exchange of information among key stakeholders, and better understanding of cold cloud duration (CCD) correlated with climatic the disease [35].Through EMPRES I disease tracking changes [37].Measurements from the Advanced Very list is one example generation of disease information.
High Resolution Radiometer sensor (AVHRR) onboard polar-orbiting satellite series operated by the NOAA are used to generate the normalized difference The Disease Tracking List (DTL) also vegetation index (NDVI) [13,37].displays the temporal evolution of daily incidence for a In East Africa, vegetation index maps have been 1-yr period.This list is shared with national and used together with ground data in monitoring vector regional field staff as well as key partner institutions, populations and RVF viral activity, establishing a which are requested to verify and validate the correlation between these two parameters.Indeed a unconfirmed events, and to follow up and search for detailed analysis was made with virus isolation data reliable sources of information.over a 25-year period and NDVI records for the study area.As the water table rises to the point where in wild birds.
All confirmed outbreaks, pending and foregoing investigations worldwide in domestic poultry and wild birds are listed.flooding may occur, the NDVI ratio approaches 0.43 to above that in the absence of full knowledge of all the 0.45 [38].The main advantage of using remote sensing transmission pathways for any particular diseases, only for prediction of RVF occurrence in East Africa is the the statistical approach is possible.This explains why much of the early epidemiology of poorly-understood relatively low cost of the system and its use may allow diseases such as cancer adopted the statistical route.for preventive measures to be taken such as the Statistical models can be extremely powerful, but vaccination of susceptible livestock and mosquito should be only a temporary substitute for the biological larval control methods [38,39].The technology has process-based models, whose development exposes been used extensively by the FAO to warn countries our full ignorance of the systems we study.It is only by facing an increased risk of the disease [40,41].

Risk maps are made showing location of confirmed outbreak in poultry and
addressing this ignorance that real progress will be The components of an Early Warning System (EWS): made [8,50].There are three components of EWS, viz., routine surveillance of the targeted disease, modelling the 3: Disease forecasting and prediction: At the heart of disease risk based on historical surveillance and early warning is a basic trade-off between the contemporary environmental data and forecasting specificity of predictions and the lead times which future risk through the use of predictive models with those predictions can provide.In general, long-range continued epidemiological and environmental forecasts give the least specific warnings, but have the surveillance [8].
advantage of providing planners with relatively long lead times.At the other extreme, systems based on 1. Disease surveillance: A sentinel network is an early detection of cases provide highly specific interactive disease surveillance system that involves information on the timing and location of outbreaks, the collection of health data on a routine basis, usually but allow little time for implementing remedial by health care professionals over a wide (usually at measures.Any prediction of risk should include an country level) area [41,42,43].In most industrialized estimate of its reliability [51, 52].nations, notification of many infectious diseases is a Epidemic prevention and control activities statutory requirement.Rapid collection of data and usually involve a chain of events and it is important to assessment of regional and national statistics leads to recognize the potential usefulness of a wide range of early detection of changes in the incidence of indicators, which may be combined to create an infections [44,45,46].The database also provides integrated prediction strategy.Such a hierarchical information for the planning and implementation of system has recently been proposed for tracking malaria intervention [8,46].The growth of such sentinel epidemics in highland areas of Africa [52].systems, from independent national networks to coordinate international information systems, has

Geographical information system (GIS)
generated a demand for health information systems GIS is an automated system for the input, storage, capable of forecasting disease [47,48].
analysis and output of spatial information.These data The present understanding that a facility-based combined with population data and previous disease sentinel surveillance system can play an important role records for prediction of diseases [53]. in providing information for monitoring communicable diseases, guiding further investigation, evaluating Applications of GIS: [53, 54, 55] control measures and predicting epidemics [8,40,49  related database supported by GIS.This software addresses the needs of data collection, retrieval, analysis and critical reporting of disease events as and when they occur and is useful to students and vet colleges, field veterinarians, administrators and technocrats [57].

NADRES (National Animal Disease Referral Expert
It Early detection and response provides better (Southern) Guwahati (North-eastern).There are six preparedness for effective control and containment of Quarantine stations viz.Delhi, Mumbai, Chennai, disease outbreaks.Animal Disease Surveillance is a Kolkata, Bangalore and Hyderabad [56,57].
key for improving disease analysis, early warning and prevents the spread of diseases.GLEWS strengthen borne diseases, while for the rest diseases GLEWS is Monitoring and Surveillance) Bangalore: This is the under development.PD_ADMAS and other surveillance agency working on surveillance of major economically and information networks are stand alone in India and important animal diseases including zoonoses.Advances there is a need for complete review of surveillance in information technology provide adequate computing system for animal diseases which may guide important techniques to develop a National livestock disease policy decisions.Successful implementation of EWS information system which is the prime need of today.The disease information is shared from diagnostic laboratories District, State or Regional level.The State Governments share this information at National level mainly through Department of Animal Husbandry, Dairying and Fisheries (DADF), Ministry of Agriculture, Government of India.[57].

Centre for Animal Disease Research and Diagnosis (CADRAD):
Figure-2.GIS-GLEWS approach for prediction of zoonotic Diseases [23] TM Epi-Info (Analysis Project on Livestock Disease include data collection from diseased animal to Forecasting/Forewarning): PD_ADMAS has developed veterinary doctor at Govt hospital/dispensary through an innovative india.admas-Epitrak epidemiology software clinical diagnosis-passed to Taluka / Block to District which is a dynamic and interactive livestock disease level then to the State Veterinary authorities.

Table - 1
[31]EWS has given the following list of diseases of common interest[31]