Trevor Shoemaker

The first confirmed Rift Valley fever outbreak outside Africa was reported in September 2000, in the Arabian Peninsula. As of February 2001, a total of 884 hospitalized patients were identified in Saudi Arabia, with 124 deaths. In Yemen, 1,087 cases were estimated to have occurred, with 121 deaths. Laboratory diagnosis of Rift Valley fever virus (RVFV) infections included virus genetic detection and characterization of clinical specimens by reverse transcription-polymerase chain reaction, in addition to serologic tests and virus isolation. Genetic analysis of selected regions of virus S, M, and L RNA genome segments indicated little genetic variation among the viruses associated with disease. The Saudi Arabia and Yemen viruses were almost identical to those associated with earlier RVF epidemics in East Africa. Analysis of S, M, and L RNA genome segment sequence differences showed similar phylogenetic relationships among these viruses, indicating that genetic reassortment did not play an important role in the emergence of this virus in the Arabian Peninsula. These results are consistent with the recent introduction of RVFV into the Arabian Peninsula from East Africa.

Effectively preventing and controlling zoonotic diseases requires a One Health approach that involves collaboration across sectors responsible for human health, animal health (both domestic and wildlife), and the environment, as well as other partners. Here we describe the Generalizable One Health Framework (GOHF), a five-step framework that provides structure for using a One Health approach in zoonotic disease programs being implemented at the local, sub-national, national, regional, or international level. Part of the framework is a toolkit that compiles existing resources and presents them following a stepwise schematic, allowing users to identify relevant resources as they are required. Coupled with recommendations for implementing a One Health approach for zoonotic disease prevention and control in technical domains including laboratory, surveillance, preparedness and response, this framework can mobilize One Health and thereby enhance and guide capacity building to combat zoonotic disease threats at the human-animal-environment interface.

Rift Valley fever (RVF) virus is a mosquito-borne virus associated with large-scale epizootics/epidemics throughout Africa and the Arabian peninsula. Virus infection can result in economically disastrous "abortion storms" and high newborn mortality in livestock. Human infections result in a flu-like illness, with 1 to 2% of patients developing severe complications, including encephalitis or hemorrhagic fever with high fatality rates. There is a critical need for a highly sensitive and specific molecular diagnostic assay capable of detecting the natural genetic spectrum of RVF viruses. We report here the establishment of a pan-RVF virus quantitative real-time reverse transcription-PCR assay with high analytical sensitivity (approximately 5 RNA copies of in vitro-transcribed RNA/reaction or approximately 0.1 PFU of infectious virus/reaction) and efficiency (standard curve slope = -3.66). Based on the alignments of the complete genome sequences of 40 ecologically and biologically diverse virus isolates collected over 56 years (1944 to 2000), the primer and probe annealing sites targeted in this assay are known to be located in highly conserved genomic regions. The performance of this assay relative to serologic assays is illustrated by testing of known RVF case materials obtained during the Saudi Arabia outbreak in 2000. Furthermore, analysis of acute-phase blood samples collected from human patients (25 nonfatal, 8 fatal) during that outbreak revealed that patient viremia at time of presentation at hospital may be a useful prognostic tool in determining patient outcome.

To the Editor: Marburg virus (MARV) and Ravn virus (RAVV), collectively called marburgviruses, cause Marburg hemorrhagic fever (MHF) in humans. In July 2007, 4 cases of MHF (1 fatal) occurred in miners at Kitaka Mine in southern Uganda. Later, MHF occurred in 2 tourists who visited Python Cave, ≈50 km from Kitaka Mine. One of the tourists was from the United States (December 2007) and 1 was from the Netherlands (July 2008); 1 case was fatal (1,2,3). The cave and the mine each contained 40,000–100,000 Rousettus aegyptiacus bats (Egyptian fruit bats). Longitudinal investigations of the outbreaks at both locations were initiated by the Viral Special Pathogens Branch of the Centers for Disease Control and Prevention (CDC, Atlanta, GA, USA, and Entebbe, Uganda) in collaboration with the Uganda Wildlife Authority (UWA) and the Uganda Virus Research Institute (UVRI). During these studies, genetically diverse MARVs and RAVVs were isolated directly from bat tissues, and infection levels of the 2 viruses were found to increase in juvenile bats on a predictable bi-annual basis (4,5). However, investigations at Kitaka Mine were stopped when the miners exterminated the bat colony by restricting egress from the cave with papyrus reed barriers and then entangling the bats in fishing nets draped over the exits. The trapping continued for weeks, and the entrances were then sealed with sticks and plastic. These depopulation efforts were documented by researchers from UVRI, the CDC, the National Institute of Communicable Diseases (Sandringham, South Africa), and UWA during site visits to Kitaka Mine (Technical Appendix Figure). In August 2008, thousands of dead bats were found piled in the forest, and by November 2008, there was no evidence of bats living in the mine; whether 100% extermination was achieved is unknown. CDC, UVRI, and UWA recommended against extermination, believing that any results would be temporary and that such efforts could exacerbate the problem if bat exclusion methods were not complete and permanent (6,7). In October 2012, the most recent known marburgvirus outbreak was detected in Ibanda, a town in southwest Uganda. Ibanda is ≈20 km from the Kitaka Mine and is the urban center that serves smaller communities in the Kitaka area. This MHF outbreak was the largest in Ugandan history: 15 laboratory-confirmed cases occurred (8). In November 2012, an ecologic investigation of the greater Ibanda/Kitaka area was initiated. The investigation included interviews with local authorities to locate all known R. aegyptiacus colonies in the area. Although minor colonies of small insectivorous bats were found, the only identifiable colony of R. aegyptiacus bats was found inside the re-opened Kitaka Mine, albeit at much reduced size, perhaps 1%–5% of that found before depopulation efforts. To determine whether the R. aegyptiacus bats that had repopulated Kitaka Mine were actively infected with marburgviruses, we tested 400 bats by using previously described methods (4,5). Viral RNA was extracted from ≈100 mg of liver and spleen tissue by using the MagMAX Total Nucleic Acid Isolation Kit (Applied Biosystems, Foster City, CA, USA) according to the manufacturer’s recommended protocol. The Fisher exact test was conducted by using IBM SPSS Statistics, version 19.0 (IBM Corp., Armonk, NY, USA). Of the 400 R. aegyptiacus bats collected, 53 (13.3%) were positive for marburgvirus RNA by quantitative reverse transcription PCR (32/233 [13.7%] adults and 21/167 [12.6%] juveniles; Technical Appendix Table); marburgvirus was isolated from tissue samples from 9 of the 400 bats. The overall level of active infection was significantly higher than that found in Kitaka Mine during 2007–2008 (5.1%) (5) (Fisher exact test, p 0.5 for both), and overall, the presence of virus-specific IgG among the bats was 16.5%, a finding consistent with that in previous studies (4,5). Figure Phylogeny of concatenated marburgvirus nucleoprotein (NP) and viral protein 35 (VP35) gene fragments as determined by using the maximum-likelihood method. Sequences from the NP (289–372 nt) and VP35 (203–213 nt) genes were amplified and ... Phylogenetic analysis of viral RNA genome fragment sequences in this study showed high marburgvirus genetic diversity, including the presence of RAVVs and MARVs. Sequences for isolates from 3 bats were nearly identical to those of the MARV isolates obtained from patients in the 2012 Ibanda outbreak (8), suggesting that bats from Kitaka Mine were a likely source of the virus. Technical Appendix: Photographs taken during August 2008–September 2009 of bat extermination efforts at Kitaka Mine, and table showing demographic characteristics of bats captured during a Marburg hemorrhagic fever outbreak investigation at the mine in November 2012, Uganda. Click here to view.(124K, pdf)