Tempering the risk: Rift Valley fever and bioterrorism

Abstract

Rift Valley fever virus (RVFV) is an arthropod-borne pathogen that primarily affects ruminants in eastern and sub-Saharan Africa first described following an outbreak on a farm in Kenya in 1931. Periodic outbreaks of RVFV since that time have resulted in significant losses to the African livestock industry as well as large numbers of infections in some of the most impoverished human populations. In one 2006/2007 outbreak across Kenya, Somalia and Tanzania alone, there were an estimated 145 000 human cases, and the ban imposed on imports after the 1997/1998 outbreak in Somalia led to a collapse of the vital livestock industry. Previously ignored, it is only in the past decade that the international community has started to take an increased interest in the disease. This followed the recognition of its potential to spread beyond the confines of the African continent after a large outbreak in Saudi Arabia in 2000. There has also been acknowledgement of the widespread presence of arthropod vectors capable of transmitting RVFV in many nonendemic regions of the world. This has led to a range of increased efforts in better understanding the virus and developing tools to predict outbreaks, combat the disease and limit its spread (Anyamba et al. 2010; Pepin et al. 2010). However, a more longstanding, parallel interest in the disease has also developed internationally; one centred around the biosecurity implications of the virus. The United States for instance, included RVFV as a candidate pathogen in its offensive biological weapons programme; a programme officially closed in 1969 (Borio et al. 2002). In more recent times, the classification of the virus as a potential bioterrorism agent has spurred investment and activity, particularly in the area of vaccine development and diagnostics (Borio et al. 2002; Sidwell & Smee 2003). While biosecurity interest has contributed to this increased funding over the past few decades, most notably from military sources such as the US Army Medical Research Institute of Infectious Diseases (USAMRIID), it may have acted as an impediment to international collaboration, with research being restricted to fewer, more expensive laboratories. After the signing of the US Patriot Act of 2002 and the classification of RVFV as a ‘select agent’, visiting experts and scientific collaborators are, for instance, now required to provide fingerprints, signed affidavits and be registered with intelligence services before working with the pathogen. Such measures are likely to act as a disincentive amongst scientists wanting to study the virus and could ultimately serve to drive experts to dedicate their efforts to other pathogens with fewer working restrictions (Animal & Plant Health Inspection Service, Centre for Disease Control & Prevention 2005, 2011). These restrictions have also been applied in parts of Europe as well, with national legislation such as the Anti-terrorism, Crime and Security Act 2001 of the UK, which also includes RVFV as a potential bioterrorism agent. For comparison and contrast, we include the current lists of biological agents and toxins around which bioterrorism legislation has been passed in the US and UK in Table 1. Focus on US policy internationally stems from its greater leadership role within the global community and the influence and impact its decisions have on people and institutions far beyond its borders. With large numbers of laboratories worldwide affected by US policy either directly through funding or indirectly as a result of political influence, restrictions have also resulted in the transfer between laboratories of RVFV samples for culture also becoming constrained and increasingly expensive. This undermines efforts to lower the industrial production costs of existing vaccines and of commercial kits for virus neutralisation and ELISA diagnostic tests (currently the prescribed tests for international livestock trade) (World Organization for Animal Health 2008). Expertise and experience thus tends to remain confined to a limited number of laboratories and companies by and large located in high income countries where investigation of the disease is neither a significant economic or health priority nor considered sufficiently profitable for drug companies. The resulting monopolies on expert technical knowledge and skills not only delays progress in developing new therapies