Open Journal of Preventive Medicine
Vol.08 No.06(2018), Article ID:85483,5 pages

Zika Virus Screening in the Kenyan Olympic Team Attending the 2016 Olympic Games in Brazil

John N. Waitumbi1*, Neha Buddhdev1, George Awinda1, Lucy Kanyara2, Zephania Irura2, Victor Ofula2, Limbaso Konongoi2, Rosemary Sang2

1Basic Science Laboratory, US Army Medical Research Directorate, Kenya/Kenya Medical Research Institute, Kisumu, Kenya

2VHF Lab, Kenya Medical Research Institute, Nairobi, Kenya

Copyright © 2018 by authors and Scientific Research Publishing Inc.

This work is licensed under the Creative Commons Attribution International License (CC BY 4.0).

Received: April 17, 2018; Accepted: June 22, 2018; Published: June 25, 2018


The 2016 Olympic Games happened at the time of heightened fears of Zika virus (ZIKV) that was causing microcephaly in newborns in Brazil. To avert or track introduction of ZIKV in Kenya, the Ministry of Health developed a public health response that involved screening of the Kenyan contingent before and after traveling to Brazil. Of the 92 team members that were screened, all but one tested negative for ZIKV IgM and IgG. The sero-positive individual had high IgM serum titers before and after travel to Brazil. When tested for potential antibody cross-reactivity to other flaviviruses that have been reported in Kenya, the sample showed high IgM cross-reactivity to West Nile, Tick-Borne Encephalitis and Yellow Fever Virus. Our data support the low risk predictions of acquiring ZIKV that were made before the Games and will help inform risk assessments for personnel traveling to endemic regions under similar circumstances in the future.


Zika Virus Screening

1. Introduction

Zika virus (ZIKV) is transmitted mainly by Aedes mosquitoes, which also transmit other flaviviruses such as dengue (DENV), yellow fever (YFV) and West Nile (WNV) viruses. The virus was first documented in 1947 when it was isolated from a sentinel rhesus monkey in the Zika forest, Uganda and thereafter in mosquitoes [1] [2] [3] . Following this discovery, a human serosurvey in the same area revealed a 6.1% specific sero-reactivity to ZIKV. Subsequent human and animal serosurveys have suggested that ZIKV is endemic to Africa and Asia. From Africa, the virus is thought to have spread to Asia. In the 1970’s, individual cases of active Zika virus infection were detected in certain parts of South-east Asia like Pakistan, India, Malaysia and Indonesia.

In 2007, the first epidemic of ZIKV was reported in the Island of Yap, Micronesia. The second outbreak was reported in 2013 in French Polynesia [3] [4] . These outbreaks were attributed to bites of the daytime-active Aedes mosquitoes. The recent South American outbreak that was first detected in Brazil in early 2015 is thought to have spread from Asia and has spread throughout the Western Hemisphere, with autochthonous transmission reported in at least 48 countries and territories in the Americas. Continued transmission was reported elsewhere in the world as well, in diverse locations such as Singapore, Micronesia, Angola, Cabo Verde and Guinea-Bissau [5] . The outbreak has been linked with birth of babies with microcephaly as a result of ZIKV infection during pregnancy, as well as complications such as Guillain-Barré syndrome in adults. Due to the explosive spread of the virus and its association with microcephaly [6] , WHO declared the outbreak in Brazil a Public Health Emergency of International Concern (1 Feb 2016) [7] . Lessons learnt from the recent outbreak in South America indicated that persistence of the virus in the semen could account for cases that occur without a known source of infection. Military personnel are at risk for infection when traveling to endemic areas, although risk is difficult to quantify in the absence of targeted studies of immunologically naive travelers to ZIKV endemic zones.

The 2016 Summer Olympics was scheduled from 5 to 21 August 2016 in Rio de Janeiro, Brazil. At the time, the possibility that the Olympic games would facilitate the spread of the virus on return of the teams to their homelands, particularly in regions where Aedes mosquitoes are prevalent, raised considerable concern [8] [9] [10] , although other analyses suggested that the risks were overstated [11] [12] [13] [14] [15] . In light of this concern, and to avert or track introduction of ZIKV in Kenya, Ministry of Health developed a public health response plan that involved screening of Olympians before and after travel to Brazil.

2. Methods

Kenyan Olympic athletes were requested to provide a blood sample before departure to Brazil and within two weeks after their return to Kenya. All participants gave informed consent that was written if the participant was literate or denoted by fingerprint if the illiterate that were also signed by an independent witnessed. Scientific and ethical approvals for the study were obtained from the Walter Reed Institute of Army Research Human Subject Protection Committee (WRAIR protocol #2343).

Ten mL of whole blood was collected and processed to provide 5 mL of sera from each of the 92 Olympians (included accompanying officials) and an aliquot tested for antibodies to ZIKV using IgM and IgG ELISA kits (Euroimmun, Luebeck, Germany). Any positive samples were further tested for antibody cross-reactivity to other flaviviruses, including WNV, tick-borne encephalitis (TBEV), and YFV.

3. Results

Of 92 participants, 31 (33.7%) were adult females and the rest were adult males (>18 years). One individual showed high IgM titers before (OD = 0.687 at 450 nm) and after travel to Brazil (OD = 1.90) compared to 0.062 for negative control and 0.924 for the positive control. The sample was unreactive by IgG. The serum samples were subsequently tested for potential antibody cross-reactivity to other flaviviruses that have been reported in Kenya. The samples had high IgM titers to WNV, TBEV, and YFV.

4. Discussion

The absence of sero-conversion to ZIKV amongst the Kenyan Olympians supports the low risk predictions that were made before the Olympic games [11] [12] [13] . A shortcoming of this study is lack of confirmatory testing such as neutralization assay on the lone subject that had high IgM titers to ZIKV. We believe this to have been a case of cross-reactivity to other flaviviruses, as evidenced by positive ELISA results for WNV, TBEV, and YFV. These results are consistent with other reports, including lack of identified cases by the World Health Organization. However, as ZIKV infection is often asymptomatic in healthy adults, it is important to follow up with specific laboratory testing to determine true infection rates, not just apparent infections. Unfortunately, few such studies were conducted. As with our study, screening of Spanish Olympic team members did not detect any evidence of ZIKV transmission [16] . These data are relevant to developing realistic risk assessments for personnel traveling to endemic areas. Such risk assessments need to take into consideration seasonality of vector populations, current circulation of pathogens, immunity in local populations, and availability of effective countermeasures.

One of the limitations of this paper is lack of adequate sociodemographic and co-morbidities data such as vaccination history before travel, pregnancy status or intention to conceive in the months following visit to Brazil, Zika counseling before the games, symptoms during or after the games.

Author Affiliations

US Army Medical Research Directorate―Kenya (John N. Waitumbi, Victor Ofula, Limbaso Konongoi, Rosemary Sang), Center for Virus Research, Kenya/Kenya Medical Research Institute (Lucy Kanyara, Limbaso Konongoi, Rosemary Sang), Division of Disease Surveillance and Response, Ministry of Health (Zephania Irura).

Ethical Statement

The study protocol was approved by the Human Subject Protection Branch of the Walter Reed Army Research Institute (WRAIR #2343).


Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the author, and are not to be construed as official, or as reflecting true views of the Department of the Army or the Department of Defense. The investigators have adhered to the policies for protection of human subjects as prescribed in AR 70-25.


Funding for this study was obtained from the Armed Forces Health Surveillance Branch (AFHSB) and it’s GEIS (Global Emerging Infections Surveillance) Section.

Cite this paper

Waitumbi, J.N., Buddhdev, N., Awinda, G., Kanyara, L., Irura, Z., Ofula, V., Konongoi, L. and Sang, R. (2018) Zika Virus Screening in the Kenyan Olympic Team Attending the 2016 Olympic Games in Brazil. Open Journal of Preventive Medicine, 8, 183-187.


  1. 1. Sikka, V., Chattu, V.K., Popli, R.K., et al. (2016) The Emergence of Zika Virus as a Global Health Security Threat: A Review and a Consensus Statement of the INDUSEM Joint working Group (JWG). Journal of Global Infectious Diseases, 8, 3-15.

  2. 2. Haddow, A.D., Schuh, A.J., Yasuda, C.Y., et al. (2012) Genetic Characterization of Zika Virus Strains: Geographic Expansion of the Asian Lineage. PLoS Neglected Tropical Diseases, 6, e1477.

  3. 3. World Health Organization (2016) The History of Zika Virus.

  4. 4. World Health Organization (2017) Situation Report: Zika Virus, Microcephaly, Guillain-Barre Syndrome, 20 January 2017. Geneva.

  5. 5. World Health Organization (2017) Situation Report: Zika Virus, Microcephaly, Guillain-Barre Syndrome, 2 February 2017. Geneva.

  6. 6. Fourth Meeting of the Emergency Committee under the International Health Regulations (2005) Regarding Microcephaly, Other Neurological Disorders and ZIKA Virus. Press Release.

  7. 7. World Health Organization (2016) WHO Director-General Summarizes the Outcome of the Emergency Committee Regarding Clusters of Microcephaly and Guillain-Barré Syndrome.

  8. 8. Attaran, A. (2016) Zika Virus and the 2016 Olympic Games. The Lancet Infectious Diseases, 16, 1001-1003.

  9. 9. USA Today (2016) Open Letter to Dr. Margaret Chan, Director-General, WHO. USA Today, Geneva.

  10. 10. Attaran, A., Caplan, A. and Igel, L. (2016) The Olympically Mismeasured Risk of Zika Virus in Rio de Janeiro. Lancet (London, England), 388, 657-658.

  11. 11. Massad, E., Coutinho, F.A. and Wilder-Smith, A. (2016) Is Zika a Substantial Risk for Visitors to the Rio de Janeiro Olympic Games? Lancet (London, England), 388, 25.

  12. 12. Lewnard, J.A., Gonsalves, G. and Ko, A.I. (2016) Low Risk of International Zika Virus Spread Due to the 2016 Olympics in Brazil. Annals of Internal Medicine, 165, 286-287.

  13. 13. Codeco, C., Villela, D., Gomes, M.F., et al. (2016) Zika Is Not a Reason for Missing the Olympic Games in Rio de Janeiro: Response to the Open Letter of Dr Attaran and Colleagues to Dr Margaret Chan, Director—General, WHO, on the Zika Threat to the Olympic and Paralympic Games. Memorias do Instituto Oswaldo Cruz, 111, 414-415.

  14. 14. Zumla, A., McCloskey, B., Bin Saeed, A.A., et al. (2016) What Is the Experience from Previous Mass Gathering Events? Lessons for Zika Virus and the Olympics 2016. International Journal of Infectious Diseases, 47, 1-4.

  15. 15. Grills, A., Morrison, S., Nelson, B., Miniota, J., Watts, A. and Cetron, M.S. (2016) Projected Zika Virus Importation and Subsequent Ongoing Transmission after Travel to the 2016 Olympic and Paralympic Games—Country-Specific Assessment, July 2016. MMWR Morbidity and Mortality Weekly Report, 65, 711-715.

  16. 16. Rodriguez-Valero, N., Borobia, A.M., Lago, M., et al. (2017) Zika Virus Screening among Spanish Team Members After 2016 Rio de Janeiro, Brazil, Olympic Games. Emerging Infectious Diseases, 23, 1426-1428.