• View in gallery
    Figure 1.

    Overlap in vector-borne infection (VBI) rapid diagnostic test results in 1,260 samples tested for all three VBIs.

  • 1.

    GBD 2013 DALYs and HALE Collaborators, 2015. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and health life expectancy (HALE) for 188 countries, 1990–2013: quantifying the epidemiological transition. Lancet 386: 21452191.

    • Search Google Scholar
    • Export Citation
  • 2.

    GBD 2013 Mortality and Cause of Death Collaborators, 2015. Global, regional, and national age-sex specific and cause-specific mortality for 240 causes of death, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 386: 117171.

    • Search Google Scholar
    • Export Citation
  • 3.

    World Health Organization, 2015. World Malaria Report 2015. Geneva, Switzerland: World Health Organization.

  • 4.

    Statistics Sierra Leone (SSL), 2014. Malaria Indicator Survey 2013 Final Report. Freetown, Sierra Leone: SSL and ICF International.

  • 5.

    Roth PJ, Grant DS, Ngegbai AS, Schieffelin J, McClelland RS, Jarrett OD, 2015. Factors associated with mortality in febrile patients in a government referral hospital in the Kenema district of Sierra Leone. Am J Trop Med Hyg 92: 172177.

    • Search Google Scholar
    • Export Citation
  • 6.

    Ansumana R, Jacobsen KH, Leski TA, Covington AL, Bangura U, Hodges MH, Lin B, Bockarie AS, Lamin JM, Bockarie MJ, Stenger DA, 2013. Reemergence of chikungunya virus in Bo, Sierra Leone. Emerg Infect Dis 19: 11081110.

    • Search Google Scholar
    • Export Citation
  • 7.

    de Araújo Lobo JM, Mores CN, Bausch DG, Christofferson RC, 2016. Serological evidence of under-reported dengue circulation in Sierra Leone. PLoS Negl Trop Dis 10: e0004613.

    • Search Google Scholar
    • Export Citation
  • 8.

    Boisen ML et al.., 2015. Multiple circulating infections can mimic the early stages of viral hemorrhagic fevers and possible human exposure to filoviruses in Sierra Leone prior to the 2014 outbreak. Viral Immunol 28: 1931.

    • Search Google Scholar
    • Export Citation
  • 9.

    Schoepp RJ, Rossi CA, Khan SH, Goba A, Fair JN, 2014. Undiagnosed acute viral febrile illnesses, Sierra Leone. Emerg Infect Dis 20: 1175.

  • 10.

    Climate Change Knowledge Portal: The World Bank Group, 2016. Average Monthly Temperature and Rainfall for Sierra Leone from 1990–2012. Available at: http://sdwebx.worldbank.org/climateportal/index.cfm?page=country_historical_climate&ThisCCode=SLE. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 11.

    Djallé D, Gody JC, Moyen JM, Tekpa G, Ipero J, Madji N, Breurec S, Manirakiza A, 2014. Performance of Paracheck™-Pf, SD Bioline malaria Ag-Pf and SD Bioline malaria Ag-Pf/pan for diagnosis of falciparum malaria in the Central African Republic. BMC Infect Dis 14: 109.

    • Search Google Scholar
    • Export Citation
  • 12.

    World Health Organization, 2015. Malaria Rapid Diagnostic Test Performance: Results of WHO Product Testing of Malaria RDTs: Round 6 (2014–2015). Geneva, Switzerland: World Health Organization.

    • Search Google Scholar
    • Export Citation
  • 13.

    World Health Organization, 2016. Malaria: Rapid Diagnostic Tests. Available at: http://www.who.int/malaria/areas/diagnosis/rapid_diagnostic_tests/en/. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 14.

    Odaga J, Sinclair D, Lokong JA, Donegan S, Hopkins H, Garner P, 2014. Rapid diagnostic tests versus clinical diagnosis for managing people with fever in malaria endemic settings. Cochrane Database Syst Rev 4: CD008998.

    • Search Google Scholar
    • Export Citation
  • 15.

    Standard Diagnostics, 2016. SD Chikungunya IgM. Available at: http://www.standardia.com/en/home/product/Rapid_Diagnostic_Test/Anti-Chickungunya_IgM.html. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 16.

    Johnson BW, Goodman CH, Holloway K, de Salazar PM, Valadere AM, Drebot MA, 2016. Evaluation of commercially available chikungunya virus immunoglobulin M detection assays. Am J Trop Med Hyg 95: 182192.

    • Search Google Scholar
    • Export Citation
  • 17.

    Kosasih H, Widjaja S, Surya E, Hadiwijaya SH, Butarbutar DP, Jaya UA, Nurhayati Alisjahbana B, Williams M, 2012. Evaluation of two IgM rapid immunochromatographic tests during circulation of Asian lineage chikungunya virus. Southeast Asian J Trop Med Public Health 43: 5561.

    • Search Google Scholar
    • Export Citation
  • 18.

    Prat CM, Flusin O, Panella A, Tenebray B, Lanciotti R, Leparc-Goffart I, 2014. Evaluation of commercially available serologic diagnostic tests for chikungunya virus. Emerg Infect Dis 20: 21292132.

    • Search Google Scholar
    • Export Citation
  • 19.

    O'Hearn AE, Voorhees MA, Fetterer DP, Wauquier N, Coomber MR, Bangura J, Fair JN, Gonzalez J-P, Schoepp RJ, 2016. Serosurveillance of viral pathogens circulating in West Africa. Virol J 13: 163.

    • Search Google Scholar
    • Export Citation
  • 20.

    Baba M, Logue CH, Oderinde B, Abdulmaleek H, Williams J, Lewis J, Laws TR, Hewson R, Marcello A, Agaro P, 2013. Evidence of arbovirus co-infection in suspected febrile malaria and typhoid patients in Nigeria. J Infect Dev Ctries 7: 5159.

    • Search Google Scholar
    • Export Citation
  • 21.

    Jentes ES, Robinson J, Johnson BW, Conde I, Sakouvougui Y, Iverson J, Beecher S, Bah MA, Diakite F, Coulibaly M, Bausch DG, 2010. Acute arboviral infections in Guinea, West Africa, 2006. Am J Trop Med Hyg 83: 388394.

    • Search Google Scholar
    • Export Citation
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Surveillance of Vector-Borne Infections (Chikungunya, Dengue, and Malaria) in Bo, Sierra Leone, 2012–2013

Donald F. Dariano IIICollege of Science, George Mason University, Fairfax, Virginia;

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Chris R. TaittCenter for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, District of Columbia;

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Kathryn H. JacobsenDepartment of Global and Community Health, George Mason University, Fairfax, Virginia;

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Umaru BanguraMercy Hospital Research Laboratory, Bo, Sierra Leone;

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Alfred S. BockarieMercy Hospital Research Laboratory, Bo, Sierra Leone;
Njala University, Bo Campus, Sierra Leone;

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Moses J. BockarieLiverpool School of Tropical Medicine, Liverpool, United Kingdom

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Joseph LahaiMercy Hospital Research Laboratory, Bo, Sierra Leone;

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Joseph M. LaminMercy Hospital Research Laboratory, Bo, Sierra Leone;

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Tomasz A. LeskiCenter for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, District of Columbia;

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Chadwick YasudaCenter for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, District of Columbia;

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David A. StengerCenter for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, District of Columbia;

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Rashid AnsumanaMercy Hospital Research Laboratory, Bo, Sierra Leone;
Njala University, Bo Campus, Sierra Leone;
Liverpool School of Tropical Medicine, Liverpool, United Kingdom

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Malaria remains a significant cause of morbidity and mortality in West Africa, but the contribution of other vector-borne infections (VBIs) to the burden of disease has been understudied. We used rapid diagnostic tests (RDTs) for three VBIs to test blood samples from 1,795 febrile residents of Bo City, Sierra Leone, over a 1-year period in 2012–2013. In total, 24% of the tests were positive for malaria, fewer than 5% were positive for markers of dengue virus infection, and 39% were positive for IgM directed against chikungunya virus (CHIKV) or a related alphavirus. In total, more than half (55%) of these febrile individuals tested positive for at least one of the three VBIs, which highlights the very high burden of vector-borne diseases in this population. The prevalence of positives on the Chikungunya IgM and dengue tests did not vary significantly with age (P > 0.36), but higher rates of malaria were observed in children < 15 years of age (P < 0.001). Positive results on the Chikungunya IgM RDTs were moderately correlated with rainfall (r2 = 0.599). Based on the high prevalence of positive results on the Chikungunya IgM RDTs from individuals Bo and its environs, there is a need to examine whether an ecological shift toward a greater burden from CHIKV or related alphaviruses is occurring in other parts of Sierra Leone or the West African region.

Malaria and other vector-borne infections (VBIs) are responsible for nearly 10% of the disability-adjusted life years lost globally each year to infectious diseases,1 and they cause nearly 1 million deaths worldwide annually.2 Sierra Leone, in West Africa, has one of the highest rates of malaria transmission among African countries,3 with about half of all outpatient clinic consultations and a sizeable proportion of inpatient hospitalizations due to malaria.4,5 However, many patients with febrile illnesses have unidentified infections. For example, 27.3% of hospitalized febrile patients in Kenema, Sierra Leone, in 2011–2012 had malaria, but more than half (53.4%) of the patients did not have a known diagnosis at discharge.5 Little is known about the epidemiological burden from nonmalarial VBIs in Sierra Leone, but preliminary reports of circulation of other VBIs such as chikungunya virus (CHIKV) and dengue virus have been published.69

As part of a larger study of the etiology of febrile illnesses in and around Bo, Sierra Leone, Mercy Hospital Research Laboratory personnel tested 1,795 blood samples from adults and children ages 6 and older who were residents of Bo city and presented to the laboratory with self-reported or clinically confirmed fever with onset within the previous 7 days. Detailed symptomatic information beyond febrile status was obtained for about one in three participants (N = 565). Informed consent from patients (or, for minor children, consent from their parents) was obtained and documented before collection of the survey data and biological specimens. The research protocol was approved by the institutional review boards of Njala University, George Mason University, the Liverpool School of Tropical Medicine, the U.S. Naval Research Laboratory, and the Sierra Leone Ethics and Scientific Review Committee.

Participants' blood samples were tested with at least one of four commercial rapid diagnostic tests (RDTs) for VBIs according to manufacturer's instructions: malaria was tested with Paracheck™ (Orchid Biomedical Systems, Goa, India) and Malaria Ag Pf/Pan (SD Bioline, Gyeonggi-do, Republic of Korea); chikungunya with Chikungunya IgM (SD Bioline); and dengue with Dengue Duo IgG/IgM/NS1 (SD Bioline). For 1,260 patients, the sample volume was sufficient to allow tests for all three VBIs to be performed. Although some of the tests measure multiple markers, a positive result for any of the markers was designated as a positive test.

Malarial antigens were detected in 23% of the samples tested using one or both of the malaria RDTs (Table 1). There were no differences in malarial detection by gender (P = 0.898) but rates were higher in children than in adults (P < 0.001). There was no significant correlation between rainfall and the percentage of tests that were positive for malaria by month (r2 = 0.034; Table 2).10 The malaria detection rates determined here are significantly lower than those documented elsewhere.3,8 This disparity may reflect an actual decrease in the malaria burden in Bo, or they could be due to the cohort tested, the age distribution of participants, or the generally poorer sensitivity of the RDTs as compared with gold standard microscopic tests, enzyme-linked immunosorbent assays (ELISAs), and polymerase chain reaction.11 However, the two malaria tests used here meet World Health Organization (WHO) procurement criteria for use in resource-limited environments,12 and in spite of sensitivity issues, RDTs may improve management of malaria in settings with inadequate diagnostic facilities.13,14

Table 1

Test results by gender and age, July 2012 to June 2013, Bo, Sierra Leone

InfectionPopulationNo. of testedNo. of positive% PositiveP value
MalariaAll1,57636122.9
Male61114123.10.898
Female96522022.8
Age 6–14883944.3< 0.001
Age 15–2944410523.6
Age 30–442715620.7
Age 45+4007418.5
DengueAll1,392624.5
Male534203.70.311
Female858424.9
Age 6–14800.00.368
Age 15–29376215.6
Age 30–44238198.0
Age 45+326164.9
ChikungunyaAll1,66864538.7
Male64824938.40.934
Female1,02039438.6
Age 6–14932931.20.391
Age 15–2949019239.2
Age 30–4428310236.0
Age 45+42714934.9
Table 2

Percentage of positive tests each month for malaria, dengue, and chikungunya

MonthMalaria
DENV
CHIKV
Average monthly rainfall (cm, 1990–2012)10
No. of positive/No. of tested% PositiveNo. of positive/No. of tested% PositiveNo. of positive/No. of tested% Positive
July 201273/14837.10/148073/14849.346.9
August 201228/13420.90/135080/13559.353.7
September 201243/13132.82/1311.569/13152.742.1
October 20128/6911.60/65021/6830.928.5
November 201229/10427.90/104023/6634.88.6
December 201217/12413.70/122046/12427.11.8
January 201339/16024.414/1578.948/13834.80.6
February 201335/13725.55/4211.945/13732.81.3
March 201328/11524.30/75051/17429.33.5
April 201323/9125.30/67047/13036.29.5
May 201327/12421.80/28063/13737.719.7
June 201329/23912.141/28814.277/25030.830.4
Correlation (r2) with rainfall0.0340.0420.5991.00

CHIKV = chikungunya virus; DENV = dengue virus.

In total, 4.5% of the participants tested positive for at least one marker of dengue virus (DENV) infection. No significant difference was observed by gender (P = 0.311) or by age (P = 0.368). Most of the dengue positive subjects (95%) were positive for the presence of anti-DENV IgG, but not anti-DENV IgM or NS1 antigen (Supplemental Table 1), suggesting that a high proportion of DENV-positive participants had antibodies from previous infections rather than suffering from an acute dengue infection at the time of testing. Although two-thirds of the DENV-positive samples were collected in June, the prevalence of DENV was not significantly correlated with rainfall (r2 = 0.042), but this may be due to the low number of positive samples. The low rates of DENV IgG/IgM seropositivity observed here agree with a recent study in neighboring Kenema,9 but several other papers report significantly higher seroprevalence of anti-DENV antibodies.7,8

A high percentage (39%) of participants had positive results on the Chikungunya IgM RDT. Participants who tested positive were significantly more likely than those with negative results to report joint pain and/or backaches (P < 0.001), both characteristic symptoms of CHIKV infections (Supplemental Table 2). We observed no significant difference in results for the Chikungunya IgM tests by gender (P = 0.934) or age (P = 0.391). Rates of positive test results showed a moderate correlation with monthly rainfall amounts (r2 = 0.599). The high proportion of positive test results on the Chikungunya IgM RDT agrees with our previous report from Bo6 and with another study performed with samples collected in the same period (35%).8 A separate study using samples from 2006 to 2008 documented much lower seroprevalence.9

The manufacturer of the Chikungunya IgM RDT reports a sensitivity of 97.1% and specificity of 91.1% compared with ELISA's.15 However, other studies have documented lower sensitivity and specificities,1618 suggesting that at least some of the positive samples may be false positive or may be due to cross-reactivity with other uncharacterized or unidentified alphaviruses. Indeed, a recent study at the Kenema Government Hospital documented a 55.8% seroprevalence rate for pan-alphavirus antibodies, indicating widespread alphaviral exposure.19 Although the test used here claims to target anti-CHIKV antibodies, we cannot rule out the possibility of cross-reaction with other related alphaviruses; to date, we have been unable to confirm the presence of CHIKV via molecular assays or culture. These results suggest that a significant proportion of population of Bo and its environs has been exposed to chikungunya or an as yet unidentified alphaviral species. It would be beneficial to retest residents of Bo using more definitive tests for CHIKV and related alphaviruses to more precisely identify the alphaviral agents causing so many febrile infections.

Among the 1,260 participants tested for all three VBIs, approximately 11% had positive results on more than one test, suggesting possible coinfections (Figure 1). About 45% of participants did not test positive for any of the three VBIs, and the etiological agent of fever remains unknown. However, it is remarkable that half of the febrile individuals in our study tested positive for malaria or chikungunya (or a cross-reacting alphavirus), which suggests a heavy burden from vector-borne disease in this city.

One of the limitations of this study is the poor overall sensitivity of RDT technology and single-timepoint testing of samples collected from febrile patients reporting to the clinic. Although WHO recognizes the role of RDTs in management of malaria in resource-limited settings,12,13 the sensitivity or selectivity of RDTs may limit their effectiveness in diagnostic applications. Nevertheless, the VBI tests used here can serve as valuable tools to identify potential public health issues. Furthermore, as the concentrations of both antigens and antibodies are greatly affected by the time of testing, a better option would be to test each subject at multiple timepoints to distinguish acute and convalescent phases. While the Chikungunya IgM test likely missed many actual CHIKV infections or detected other alphaviral infections, the high numbers of positives observed here point to the possibility of a significant alphaviral problem in the tested population, which requires further investigation. A larger set of VBI tests for various alphaviruses (such as o'nyong-nyong virus), bunyaviruses (such as Tahyna virus), and flaviviruses (such as West Nile, Zika, and yellow fever viruses)20,21 should be used in Bo and its environs to identify the true burden of nonmalarial VBIs in this area.

Figure 1.
Figure 1.

Overlap in vector-borne infection (VBI) rapid diagnostic test results in 1,260 samples tested for all three VBIs.

Citation: The American Journal of Tropical Medicine and Hygiene 97, 4; 10.4269/ajtmh.16-0798

REFERENCES

  • 1.

    GBD 2013 DALYs and HALE Collaborators, 2015. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and health life expectancy (HALE) for 188 countries, 1990–2013: quantifying the epidemiological transition. Lancet 386: 21452191.

    • Search Google Scholar
    • Export Citation
  • 2.

    GBD 2013 Mortality and Cause of Death Collaborators, 2015. Global, regional, and national age-sex specific and cause-specific mortality for 240 causes of death, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 386: 117171.

    • Search Google Scholar
    • Export Citation
  • 3.

    World Health Organization, 2015. World Malaria Report 2015. Geneva, Switzerland: World Health Organization.

  • 4.

    Statistics Sierra Leone (SSL), 2014. Malaria Indicator Survey 2013 Final Report. Freetown, Sierra Leone: SSL and ICF International.

  • 5.

    Roth PJ, Grant DS, Ngegbai AS, Schieffelin J, McClelland RS, Jarrett OD, 2015. Factors associated with mortality in febrile patients in a government referral hospital in the Kenema district of Sierra Leone. Am J Trop Med Hyg 92: 172177.

    • Search Google Scholar
    • Export Citation
  • 6.

    Ansumana R, Jacobsen KH, Leski TA, Covington AL, Bangura U, Hodges MH, Lin B, Bockarie AS, Lamin JM, Bockarie MJ, Stenger DA, 2013. Reemergence of chikungunya virus in Bo, Sierra Leone. Emerg Infect Dis 19: 11081110.

    • Search Google Scholar
    • Export Citation
  • 7.

    de Araújo Lobo JM, Mores CN, Bausch DG, Christofferson RC, 2016. Serological evidence of under-reported dengue circulation in Sierra Leone. PLoS Negl Trop Dis 10: e0004613.

    • Search Google Scholar
    • Export Citation
  • 8.

    Boisen ML et al.., 2015. Multiple circulating infections can mimic the early stages of viral hemorrhagic fevers and possible human exposure to filoviruses in Sierra Leone prior to the 2014 outbreak. Viral Immunol 28: 1931.

    • Search Google Scholar
    • Export Citation
  • 9.

    Schoepp RJ, Rossi CA, Khan SH, Goba A, Fair JN, 2014. Undiagnosed acute viral febrile illnesses, Sierra Leone. Emerg Infect Dis 20: 1175.

  • 10.

    Climate Change Knowledge Portal: The World Bank Group, 2016. Average Monthly Temperature and Rainfall for Sierra Leone from 1990–2012. Available at: http://sdwebx.worldbank.org/climateportal/index.cfm?page=country_historical_climate&ThisCCode=SLE. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 11.

    Djallé D, Gody JC, Moyen JM, Tekpa G, Ipero J, Madji N, Breurec S, Manirakiza A, 2014. Performance of Paracheck™-Pf, SD Bioline malaria Ag-Pf and SD Bioline malaria Ag-Pf/pan for diagnosis of falciparum malaria in the Central African Republic. BMC Infect Dis 14: 109.

    • Search Google Scholar
    • Export Citation
  • 12.

    World Health Organization, 2015. Malaria Rapid Diagnostic Test Performance: Results of WHO Product Testing of Malaria RDTs: Round 6 (2014–2015). Geneva, Switzerland: World Health Organization.

    • Search Google Scholar
    • Export Citation
  • 13.

    World Health Organization, 2016. Malaria: Rapid Diagnostic Tests. Available at: http://www.who.int/malaria/areas/diagnosis/rapid_diagnostic_tests/en/. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 14.

    Odaga J, Sinclair D, Lokong JA, Donegan S, Hopkins H, Garner P, 2014. Rapid diagnostic tests versus clinical diagnosis for managing people with fever in malaria endemic settings. Cochrane Database Syst Rev 4: CD008998.

    • Search Google Scholar
    • Export Citation
  • 15.

    Standard Diagnostics, 2016. SD Chikungunya IgM. Available at: http://www.standardia.com/en/home/product/Rapid_Diagnostic_Test/Anti-Chickungunya_IgM.html. Accessed December 21, 2016.

    • Search Google Scholar
    • Export Citation
  • 16.

    Johnson BW, Goodman CH, Holloway K, de Salazar PM, Valadere AM, Drebot MA, 2016. Evaluation of commercially available chikungunya virus immunoglobulin M detection assays. Am J Trop Med Hyg 95: 182192.

    • Search Google Scholar
    • Export Citation
  • 17.

    Kosasih H, Widjaja S, Surya E, Hadiwijaya SH, Butarbutar DP, Jaya UA, Nurhayati Alisjahbana B, Williams M, 2012. Evaluation of two IgM rapid immunochromatographic tests during circulation of Asian lineage chikungunya virus. Southeast Asian J Trop Med Public Health 43: 5561.

    • Search Google Scholar
    • Export Citation
  • 18.

    Prat CM, Flusin O, Panella A, Tenebray B, Lanciotti R, Leparc-Goffart I, 2014. Evaluation of commercially available serologic diagnostic tests for chikungunya virus. Emerg Infect Dis 20: 21292132.

    • Search Google Scholar
    • Export Citation
  • 19.

    O'Hearn AE, Voorhees MA, Fetterer DP, Wauquier N, Coomber MR, Bangura J, Fair JN, Gonzalez J-P, Schoepp RJ, 2016. Serosurveillance of viral pathogens circulating in West Africa. Virol J 13: 163.

    • Search Google Scholar
    • Export Citation
  • 20.

    Baba M, Logue CH, Oderinde B, Abdulmaleek H, Williams J, Lewis J, Laws TR, Hewson R, Marcello A, Agaro P, 2013. Evidence of arbovirus co-infection in suspected febrile malaria and typhoid patients in Nigeria. J Infect Dev Ctries 7: 5159.

    • Search Google Scholar
    • Export Citation
  • 21.

    Jentes ES, Robinson J, Johnson BW, Conde I, Sakouvougui Y, Iverson J, Beecher S, Bah MA, Diakite F, Coulibaly M, Bausch DG, 2010. Acute arboviral infections in Guinea, West Africa, 2006. Am J Trop Med Hyg 83: 388394.

    • Search Google Scholar
    • Export Citation

Author Notes

Address correspondence to Rashid Ansumana, Mercy Hospital Research Laboratory, Bo, Sierra Leone. E-mail: rashidansumana@gmail.com

Authors' addresses: Donald F. Dariano III, George Mason University, College of Science, Fairfax, VA, E-mail: dariano9933@gmail.com. Chris R. Taitt, Tomasz A. Leski, Chadwick Yasuda, and David A. Stenger, Center for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC, E-mail: chris.taitt@nrl.navy.mil, tomasz.leski@nrl.navy.mil, chadwick.yasuda@nrl.navy.mil, and david.stenger@nrl.navy.mil. Kathryn H. Jacobsen, Global and Community Health, George Mason University, Fairfax, VA, E-mail: kjacobse@gmu.edu. Umaru Bangura, Alfred S. Bockarie, Joseph Lahai, Joseph M. Lamin, and Rashid Ansumana, Mercy Hospital Research Laboratory, Bo, Sierra Leone, E-mails: umarbans@yahoo.co.uk, asbock2@gmail.com, josephlahaiphlebo@gmail.com, jmlamin6076@gmail.com, and rashidansumana@gmail.com. Moses J. Bockarie, South-South Cooperation, and European and Developing Countries Clinical Trials Partnership (EDCTP) Medical Research Council, Tygerberg, Cape Town, South Africa, E-mail: bockarie@edctp.org.

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