BackgroundSub-Saharan Africa is home to a variety of pathogens, but disease surveillance and the healthcare infrastructure necessary for proper management and control are severely limited. Lassa virus, the cause of Lassa fever, a severe hemorrhagic fever in humans is endemic in West Africa. In Sierra Leone at the Kenema Government Hospital Lassa Diagnostic Laboratory, up to 70 % of acute patient samples suspected of Lassa fever test negative for Lassa virus infection. This large amount of acute undiagnosed febrile illness can be attributed in part to an array of hemorrhagic fever and arthropod-borne viruses causing disease that goes undetected and untreated.MethodsTo better define the nature and extent of viral pathogens infecting the Sierra Leonean population, we developed a multiplexed MAGPIX® assay to detect IgG antibodies against Lassa, Ebola, Marburg, Rift Valley fever, and Crimean-Congo hemorrhagic fever viruses as well as pan-assays for flaviviruses and alphaviruses. This assay was used to survey 675 human serum samples submitted to the Lassa Diagnostic Laboratory between 2007 and 2014.ResultsIn the study population, 50.2 % were positive for Lassa virus, 5.2 % for Ebola virus, 10.7 % for Marburg virus, 1.8 % for Rift Valley fever virus, 2.0 % for Crimean-Congo hemorrhagic fever virus, 52.9 % for flaviviruses and 55.8 % for alphaviruses.ConclusionsThese data exemplify the importance of disease surveillance and differential diagnosis for viral diseases in Sierra Leone. We demonstrate the endemic nature of some of these viral pathogens in the region and suggest that unrecognized outbreaks of viral infection have occurred.

Crimean-Congo hemorrhagic fever (CCHF) is the most medically important tick-borne viral disease of humans and tuberculosis is the leading cause of death worldwide by a bacterial pathogen. These two diseases overlap geographically, however, concurrent infection of CCHF virus (CCHFV) with mycobacterial infection has not been assessed nor has the ability of virus to persist and cause long-term sequela in a primate model. In this study, we compared the disease progression of two diverse strains of CCHFV in the recently described cynomolgus macaque model. All animals demonstrated signs of clinical illness, viremia, significant changes in clinical chemistry and hematology values, and serum cytokine profiles consistent with CCHF in humans. The European and Asian CCHFV strains caused very similar disease profiles in monkeys, which demonstrates that medical countermeasures can be evaluated in this animal model against multiple CCHFV strains. We identified evidence of CCHFV persistence in the testes of three male monkeys that survived infection. Furthermore, the histopathology unexpectedly revealed that six additional animals had evidence of a latent mycobacterial infection with granulomatous lesions. Interestingly, CCHFV persisted within the granulomas of two animals. This study is the first to demonstrate the persistence of CCHFV in the testes and within the granulomas of non-human primates with concurrent latent tuberculosis. Our results have important public health implications in overlapping endemic regions for these emerging pathogens.

Viral hemorrhagic fevers, because of their high mortality rates, the lack of medical countermeasures, and their potential use as instruments of bioterrorism, pose a significant threat to the developed and the developing areas of the world. The key to preventing the spread of these diseases is early and accurate detection. For decades, the gold-standard immunoassay for hemorrhagic fever detection has been the enzyme-linked immunosorbent assay (ELISA); however, newer technologies are emerging with increased sensitivities. One such technology is the Luminex MagPix platform using xMAP microspheres. Here, we compare the MagPix platform with a traditional ELISA for IgM and antigen detection of infections from Lassa and Ebola viruses (LASV and EBOV, respectively). For IgM detection in nonhuman primate samples, the MagPix platform was 5 and 25 times more sensitive in detecting LASV and EBOV, respectively, compared to that with ELISA. For antigen detection in buffer, the MagPix platform was 25 and 2.5 times more sensitive in detecting lower levels of LASV and EBOV, respectively. In both IgM and antigen detection assays, the MagPix platform demonstrated excellent reproducibility at the lower limit of detection (LLOD). These findings demonstrate that the MagPix platform is a viable diagnostic replacement for the ELISA for viral hemorrhagic fevers.KEYWORDS ELISA, MagPix, Ebola virus, immunoassays, Lassa virus, viral hemorrhagic fever H emorrhagic fevers are a part of the normal disease burden in Africa. In the developed world, they are a concern because of their potential use as bioterrorism agents. Lassa virus (family, Arenaviridae) and ebolaviruses (family, Filoviridae) are hemorrhagic fever viruses that are endemic in several African countries (1, 2). Disease outbreaks with these viruses have significant medical and social impacts. Case fatality rates can be as high as 65% for Lassa virus (LASV) and as high as 90% for ebolaviruses (3,4). Their high mortality rates combined with their ease of transmission and the lack of vaccines or effective treatments render them extremely dangerous pathogens.Early during an infection, hemorrhagic fever viruses have a clinical presentation that is similar to other more common febrile illnesses (5, 6). A rapid and accurate diagnosis of hemorrhagic fever viruses is critical for limiting the spread of disease and enabling an earlier more effective treatment. Traditionally, enzyme-linked immunosorbent assays (ELISAs) have been used for the detection of a virus-specific antigen and/or IgM antibodies (7,8).ELISA immunodiagnostics are the standard by which other diagnostics are evaluated. ELISA has been commonly used for the detection of LASV and Ebola virus (EBOV) for many years; however, newer immunodiagnostic platforms that offer multiplex

During 2013–2014, we collected 1,926 serum samples from humans and 4,583 ticks (Hyalomma asiaticum or Dermacentor nuttalli) in select regions of Mongolia to determine the risk for Crimean-Congo hemorrhagic fever virus (CCHFV) infection among humans in this country. Testing of human serum samples by ELISA demonstrated an overall CCHFV antibody prevalence of 1.4%; Bayankhongor Province had the highest prevalence, 2.63%. We pooled and analyzed tick specimens by real-time reverse transcription PCR; 1 CCHFV-positive H. asiaticum tick pool from Ömnögovi was identified. In phylogenetic analyses, the virus’s partial small segment clustered with CCHFV isolates from Central Asia, and the complete medium segment grouped with CCHFV isolates from Africa, Asia, and the Middle East. This study confirms CCHFV endemicity in Mongolia and provides information on risk for CCHFV infection. Further research is needed to better define the risk for CCHFV disease to improve risk mitigation, diagnostics, and surveillance.

Tick-borne infections are a significant threat to public health, particularly in regions where individuals frequently enter tick habitats. Roughly 26% of the population in Mongolia practice nomadic pastoralism and are considered at high risk of exposure to ticks and the diseases they carry. This study tested ticks from Mongolia’s southern border for Rickettsia spp. to better understand the epidemiology of tick-borne diseases in the region. Dermacentor nuttalli and Hyalomma asiaticum ticks (n = 4022) were pooled and tested for Rickettsia spp. by real-time PCR. Melt-curve analyses and Sanger sequencing were used to identify Rickettsia species. Approximately 64% of the 786 tick pools tested positive for Rickettsia bacteria. Melt curve analyses identified four different Rickettsia species circulating in these tick pools. Amplicon sequencing of the ompA gene identified Rickettsia spp. that closely resembled R. raoultii and R. sibirica. Dermacentor nuttalli ticks from Govi-Altai had the highest maximum likelihood estimation infection rate 48.4% (95% CI: 41.7–56.5%), while Hyalommaasiaticum collected in Omnogovi had a rate of 7.6% (95% CI: 6.2–9.2%). The high detection of Rickettsia suggests a substantial risk of infection in southern Mongolia. Further studies are necessary to investigate the clinical burden of tick-borne diseases in Mongolia.