The role of wildlife in transboundary animal diseases in Kenya
SUMMARY OF RECENT HISTORY (SINCE 2000) OF SELECTED TRANSBOUNDARY DISEASES IN KENYA
Avian influenza A (H7N9 & H1N1)
The 2009 Pandemic influenza A (H1N1) was first characterized in Kenya on 29th June, 2009 (Matheka et al., 2013). Thereafter sentinel data from ten sites in Kenya have identified both influenza type A and B circulating in Kenya (Muthoka, 2012). The distribution of these influenza types between 2006 to 2011 was as follows: Type A pandemic (H1N1) 2009 (28%), Type A (H1N1) seasonal (10%), Type A (H3N3) seasonal (24%), Type B (31%) and uncharacterized (7%) (Muthoka, 2012). In 2012 the predominant strain in Kenya was H3N2 with a seasonal occurrence (Achilla et al., 2009, Muthoka, 2012).
Foot and Mouth Disease
The Foot and Mouth disease outbreaks (see Figure 1 and 4) that have occurred in Kenya during the period 2004-2006 have involved serotypes: O, A, C, SAT1 and SAT2 (Sangula, 2006, CDC, 2007). The outbreak serotype distribution over the years has been as follows: 1 outbreak of SAT 1 and 19 of SAT2 reported in 2004; 3 of SAT1 and 10 of SAT2 reported in 2005; and 7 of SAT 1 and 4 of SAT 2 reported in 2006 (Sangula, 2006).
Rift Valley Fever
The most recent outbreak of Rift Valley Fever in Kenya occurred between November 2006 to January 2007 (see Figure 4) that affected 6 provinces and 29 administrative districts (see Figure 2 & 3) out of the total 8 provinces and 69 administrative districts, respectively (Munyua et al., 2010) as a result of extraordinarily heavy rainfall during October-December 2006 (CDC, 2007). Following the El-nino development advisory that was issued by Kenya Meteorological Department on 22nd September, 2015 (Kenya, 2015a), as of 19th February, 2016 (time of writing this assignment) there has not been any confirmed RVF case in Kenya preceding the late-2015 El-Nino rains.
The last known outbreak of Rinderpest in Kenya was of cattle reported in Meru National Park in 2001 (Omiti and Irungu, 2010) and a buffalo (AVMA, 2011). Since then Kenya has been free of Rinderpest (see Figure 4)
RISK OF WILDLIFE IN THE EPIDEMIOLOGY OF FMD IN KENYA
Records at the Kenya national Foot-and-Mouth Disease Laboratory show that previous studies on FMD in Kenya have mainly focused on cattle and rarely on other susceptible domestic species (Wekesa et al., 2014) and only to a minor extent on wildlife. However, in 1979, a field survey isolated SAT1 and SAT2 FMDVs from buffalo populations in the southern part of Kenya (Anderson et al., 1979).
(Bronsvoort et al., 2008) demonstrated a high and increasing seroprevalence of Foot and Mouth Disease Virus (FMDV) between the years 1994-2002 among the African buffalo (Syncerus caffer) in Eastern Africa (Kenya inclusive) with a high sero-conversation early in life (1-2 years). The study also found that the dominant serotypes were SAT2, SAT1 and then SAT3 in that order, although the buffalo seemed to be more associated to maintain the SAT2 as compared to the other serotypes.
FMDV has also been shown to infect several wild species that are found in Laikipia, with the African elephant proposed to play a potential transmission role (Aftosa, 2014). This potential transmission is further purported by (Benka, 2012) where 92.2% of the respondents in Laikipia-Kenya noted an increased contact time and population of wildlife in the recent past, especially the elephants and the buffaloes. The OIE WAHIS database also shows existence of FMD outbreaks in Kenya among wildlife (refer to Figure 4), with suspected cases in 2009 and confirmed cases between 2010-2011 that were limited to one or more zones (OIE, 2016b).
A study by (Wekesa et al., 2015) found that the Buffalo harbored SAT1 and SAT2 serotypes (see Figure 5). Wildlife have been implicated, through molecular epidemiology, as a possible culprit for the upsurge of the SAT1 and SAT2 epidemics in Kenya because of the intimate interaction of livestock and wildlife in the pastoral ecosystem (Sangula, 2006, CDC, 2007). This makes it imperative to undertake antigenic comparison to determine if the current vaccines confer protection against these co-shared serotypes at the livestock-wildlife interface.
The cross-border movement of wildlife from Kenya to Tanzania (see Figure 6) could be facilitating the complex and trans-boundary nature of this disease and further complicating its epidemiology. This could mean that control measures need to be collaborative between the governments of Kenya and Tanzania, employing a One Health concept.
BIOLOGIC, SOCIOLOGIC, AND ECONOMIC FACTORS IMPORTANT IN THE CONTROL AND/OR ELIMINATION OF FMD IN KENYA
Wide array of serotypes: There are several serotypes for the FMDV with antigenic variations within each serotype making it impossible for one serotype to confer immunity against another serotype (OIE, 2012), and therefore in practice vaccine matching becomes necessary with the field strains (Chepkwony, 2011).
FMDV is highly contagious: Transmission can be facilitated through contact with infected animals, their excretions, secretions, or contaminated fomites and products (OIE, 2012, USDA, 2013). It has also been shown that humans can possibly transmit the FMDV to susceptible animals during FMD outbreaks (USDA, 2013) and therefore responders should uphold biosecurity measures.
Wide range of susceptible hosts: Many of the cloven-hoofed wildlife and domestic species at the wildlife-livestock interface in Kenya, including: cattle, goats, sheep, and pigs are susceptible to FMDV, and this presents a possible spillover of infection into livestock or sympatric cloven-hoofed wildlife (OIE, 2012 1512).
Carrier state: Cattle, sheep, and goats can become carriers or persistently infected even after successful vaccination (Chhetri et al., 2010). The carrier state is a complication which should be considered during outbreak situations (Grubman and Baxt, 2004).
FMDV is moderately stable in the environment: Under certain conditions the FMDV can maintain infectivity in the environment for extended periods of time (USDA, 2013). It is essential for livestock owners and producers to maintain sound biosecurity practices as outlined by (OIE, 2016a) to prevent introduction/spread of the virus during outbreaks.
Illegal movement routes: Illegal stock routes for trade as a result of drought, forced cattle movement due to cattle rustling and across the borders are some of the main causes of FMDV spread in Kenya (Chepkwony, 2011). Therefore there should be coordinated livestock movement control at borders and stop cattle rustling.
Pastoralism: Pastoral long distance movement of animals, and high stocking densities facilitates the widespread of viral particles (OIE and FAO, 2012) within and across borders.
Several differential diagnosis: FMD cannot be differentiated clinically from other similar diseases and therefore an suspected case is best confirmed through laboratory diagnosis (OIE, 2012).
The social factors to be considered are:
- Effective, timely and accurate communications with the affected premises, stakeholders, farmers and animal keepers, the public and the media so as to reduce the impact and spread of disease and to provide accurate and timely updates on latest situation
- Timely risk communication to the public, region and international community during an outbreak or incident to ensure effective representation of Kenya disease control activities.
- Background knowledge on the structure of livestock production systems to understand epidemiology and control options suitable at the local setting
- Public health implications since FMD can cause mild disease in humans and accompanied by floods during the rains
- Assurance to the public and international community of safe commodities for trade
- Public acceptance especially when it comes to: culling of animals and animal welfare perspectives
- Provision of support services e.g. psychological support during mass death
- How to counter misinformation and misconceptions especially through media
- Supporting legal framework in Kenya: The animal diseases Act Chapter 364; Public Health act cap 242; Meat Control Act cap 356; Procurement and audit act
Some of the economic factors to consider are (OIE, 2014):
- Costs and benefits of intervention
- Availability of resources
- Logistics and ease of implementation
- Stakeholder engagement especially the public-private partnerships
- Environmental impact
- Political will
- Incentives and compensation
- Budget and financial resources planning
IMPORTANT STAKEHOLDERS TO BE INVOLVED IN THE CONTROL
Ministry of Agriculture, Livestock and Fisheries: Kenya’s economy is dominated by the agricultural sector and FMD poses a great threat to it both as production losses and indirect losses.
Ministry of Health: FMD has public health implications e.g. flooding & zoonotic.
Ministry of Tourism and other local & international travel organisations: The African wildlife are a major tourist attraction and if there is a risk of infection from wildlife this may impact negatively on the tourism industry
Devolved local government administration: have the responsibility to enforce disease control measures, offer administrative and information technology resources such as administered movement licensing, provide advice and support to affected sectors.
Central Veterinary Laboratory: has the capacity to provide and interpret diagnostic and surveillance data and provide disease-specific expert knowledge in terms of the epidemiology and control measures of FMD.
Regional or Local NGOs, CBOs, FBOs, youth groups, churches etc.: These groups will help inform local decision making as appropriate and will assist with ensuring that developments in local operations are communicated to all relevant parties, including those who are not engaged with industry groups and sector councils, and can be a challenge to reach.
Ministry of Defence and Police: They will play the role of organization and logistical arrangements especially when it comes to intensifying biosecurity patrols and protecting the public order with individual roles such as: enforcement of movement controls with local authorities, policing of control zones, coordination of legal entry to premises etc.
Global facilitation/technical assistance bodies: such as GARC (Global Alliance for Rabies Control) who can act as a liaison body between national governments, community stakeholders and the international FAO-OIE-WHO tripartite.
Regional banks and stakeholders: they have contributed and still contribute significantly to FMD control efforts in Africa.
Ministry of Environment and Natural Resources: Will contributed to development of carcass transport arrangements and advice on planning, air and environment quality issues relating to disposal of carcasses and cleanup.
Foot and Mouth Disease champion: Having an FMD champion from a country that has successfully eradicated FMD so as to provide ‘good practices’ that can locally be adopted in the prevention and control of FMD
Kenya Veterinary Vaccines Production Institute (KEVEVAPI): Since they produce the FMD vaccine they will play a valuable contribution in its control through vaccine provision
Local community: They have and are already suffering because of the production losses as a result of FMD and therefore will be a direct beneficiary and implementer of prevention/control strategies proposed.
The media: They will disseminate key messages on the prevention and control of FMD to the public
CONCLUSIONS AND RECOMMENDATIONS
It is clear that wildlife have a potential role in the epidemiology of Foot and Mouth Disease in Kenya and the neighboring regions, although the existing information is still limited. Hence, Foot and Mouth Disease control in Kenya should principally target on reducing the high burden of disease among livestock and consequently limit the livestock-wildlife interaction through collaborative efforts with stakeholders and between countries that share a border with Kenya that facilitate cross-border movement of livestock and wildlife. This can be achieved through a number of ways:
- Strengthen surveillance systems: Build the capacity of local laboratories and promote regional integrated surveillance systems so as to facilitate early detection and rapid response to any FMD outbreak. At the same time develop multivalent vaccines targeting the shared serotypes between livestock and wildlife.
- Disease prevention and infection control: with the aim of slowing the spread of FMD and end the outbreak so as to prevent new cases from arising. This can be at the:
- Human level through: public health education; behavior change communication especially targeting the pastoralists to avoid risky practices that propagate transmission between communities and across borders
- Animal level through: strategic livestock vaccination in specific hot spots; imposition of quarantines in affected areas and slaughter bans.
- Cross-border mitigation: The cross-border movement of livestock and wildlife necessitates that control measures need to be collaborative between the governments employing a One Health concept.
- Support services: Contingency plans to be in place to provide support in regard to floods that can result to partial/full harm to humans which may require provision of temporary support facilities and relief aid to both humans and animals
- Targeted and coordinated communication: The aim is to provide accurate, timely and easy to understand information through coordinated communication among all relevant stakeholders to ensure consistent messages to the general public and at the same time address the circulating rumours, misinformation and conflicting information.
- Standard Operating Procedures and protocols: Should be available before the outbreak and address: simulation and training, quarantine measures, handling of samples, vaccination of livestock, surveillance, rapid response teams, biosecurity and biosafety, communication protocol, and allocation of responsibilities.
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