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Volume 25, Number 12—December 2019
Research Letter

MERS-CoV in Camels but Not Camel Handlers, Sudan, 2015 and 2017

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Elmoubasher Farag1, Reina S. Sikkema1, Ahmed A. Mohamedani, Erwin de Bruin, Bas B. Oude Munnink, Felicity Chandler, Robert Kohl, Anne van der Linden, Nisreen M.A. Okba, Bart L. Haagmans, Judith M.A. van den Brand, Asia Mohamed Elhaj, Adam D. Abakar, Bakri Y.M. Nour, Ahmed M. Mohamed, Bader Eldeen Alwaseela, Husna Ahmed, Mohd Mohd Alhajri, Marion Koopmans, Chantal Reusken2, and Samira Hamid Abd Elrahman2Comments to Author 
Author affiliations: Ministry of Public Health, Doha, Qatar (E. Farag, M.M. Alhajri); Erasmus Medical Centre, Rotterdam, the Netherlands (R.S. Sikkema, E. de Bruin, B.B.O. Munnink, F. Chandler, R. Kohl, A. van der Linden, N.M.A. Okba, B.L. Haagmans, M. Koopmans, C. Reusken); University of Gezira, Wad Medani, Sudan (A.A. Mohamedani, S.H.A. Elrahman); Utrecht University, Utrecht, the Netherlands (J.M.A. van den Brand); Blue Nile National Institute for Communicable Diseases, Wad Medani (A.M. Elhaj, A.D. Abakar, B.Y.M. Nour, A.M. Mohamed, S.H.A. Elrahman); Tamboul Camel Research Centre, Tamboul, Sudan (B.E. Alwaseela, H. Ahmed); National Institute for Public Health and the Environment, Bilthoven, the Netherlands (C. Reusken)

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Abstract

We tested samples collected from camels, camel workers, and other animals in Sudan and Qatar in 2015 and 2017 for evidence of Middle East respiratory syndrome coronavirus (MERS-CoV) infection. MERS-CoV antibodies were abundant in Sudan camels, but we found no evidence of MERS-CoV infection in camel workers, other livestock, or bats.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus from camels that can cause serious respiratory disease and death in humans (1). Camel populations across the Middle East and Africa are highly seropositive. However, the only known human cases of clinical MERS-CoV infection in Africa were related to travel from Qatar and Saudi Arabia (https://ecdc.europa.eu/sites/portal/files/media/en/publications/Publications/RRA_MERS-CoV_7th_update.pdf), and serologic evidence for infections in humans resulting from camel exposure in Africa is limited (2).

The only published report of MERS-CoV circulation in camels in Sudan involved the testing of camel samples from 1983; that study found a seroprevalence of 82% (49/60) (3). Two publications from Egypt describe evidence of possible MERS-CoV circulation in Sudan, reporting a seroprevalence of 91% (543/594) in camels originating from Sudan and a seroprevalence of 92% (48/52), combined with a reverse transcription PCR positivity rate of 5.6%, in camels originating from Ethiopia and Sudan (3). Neither study presented conclusive evidence for MERS-CoV circulation in Sudan. Here, we provide the results of a study conducted in the Butana region of Al Jazirah, Sudan, to investigate the local point prevalence of MERS-CoV and MERS-CoV antibodies among camel handlers, camels, and other animals in 2015 and 2017. We also report the results of a MERS-CoV screening in camels from Sudan sampled in Qatar directly upon importation.

We collected samples from humans and animals at a live animal market, an outdoor slaughter area adjacent to that market, and the Tamboul Camel Research Centre (TCRC), all located in Tamboul, Sudan. Overall, ≈1,660 camels and additional other livestock are usually present at the animal market; these camels come from individual small farms, where they are largely kept under free-roaming conditions. At the TCRC, ≈100 camels are generally present and kept out of contact with other camels. Before their arrival at the TCRC, they were herded on the Butana Plain. We also collected samples from 90 Sudan camels that were imported into Qatar in 2015. After arriving at the Hamad International Airport in Doha, Qatar, these camels were directly transported to the Al Shahaniya animal market in Doha. We sampled them immediately after their arrival. We stored all samples locally (1–1.5 years in Sudan, 1 month in Qatar) and tested them after shipment to the Netherlands.

We tested 56 human, 190 camel, 3 bat, 14 donkey, 15 cow, 15 sheep, and 15 goat serum samples for antibodies against MERS-CoV spike S1 using the protein microarray technique (4). We performed a virus neutralization test and a spike S1 protein–based ELISA (human serum samples only) to confirm the detection of MERS-CoV antibodies by protein microarray (5). In confirmatory tests, we included equal numbers of negative serum samples of the same species, when available. We considered samples positive if results of all tests were positive (protein microarray cutoff 1:20, 50% plaque-reduction neutralization titer cutoff 1:20, ELISA cutoff optical density 0.5). To resolve problems with possible mislabeling, we tested all animal serum samples collected in 2017 with a cytochrome B gene PCR to confirm species origins (6). We tested camel nasal (n = 168), nasopharyngeal (n = 24), and rectal (n = 61) swab specimens and milk (n = 33), urine (n = 30), and fecal (n = 42) samples for MERS-CoV RNA using a reverse transcription PCR targeting the upstream of envelope and nucleocapsid genes, as described previously (7,8). In addition, we tested legs of camel ticks (Hyalomma dromedarii) and bat (Tadarida spp.) tissues collected at the TCRC in 2015 for MERS-CoV RNA.

In 2015, a total of 92% of camels in Sudan and 99% of camels exported to Qatar from Sudan were MERS-CoV seropositive (Table). In 2017, all camels tested in Sudan were seropositive. No MERS-CoV antibodies were found in human or bat serum samples or serum samples from livestock other than camels. MERS-CoV RNA was detected in the nasal swabs from 3 camels imported into Qatar in 2015 but in no other samples.

The results of this study are in agreement with other seroepidemiologic studies performed in Africa. The camel population was highly seropositive for MERS-CoV, and none or a low percentage of nasal or nasopharyngeal swabs from camels were positive for MERS-CoV RNA. As shown before in other countries in Africa, human serum samples did not show neutralizing activity against MERS-CoV (2). In 1 study in Kenya, 2 of 1,122 livestock handlers were found positive for MERS-CoV neutralizing antibodies (9). Other livestock were also seronegative for MERS-CoV in our study, a finding in agreement with most serosurveys, although some sheep, goats, and donkeys and 1 cow have been reported to have MERS-CoV antibodies (3,10).

The number of human and livestock samples tested was low in this investigation. Therefore, the results of this study are not conclusive. However, this study provides preliminary insight into MERS-CoV circulation in Sudan, the country with the third largest dromedary camel population in the world (http://www.fao.org/faostat/en/#data/QA). We show evidence of extensive MERS-CoV circulation in camels but no evidence of circulation in other livestock, bats, and humans.

Ms. Sikkema is a doctoral candidate at the Erasmus Medical Centre, Rotterdam, the Netherlands. Her research interests are mainly focused on the risk-based surveillance of MERS-CoVs in animals and humans. Mr. Farag is acting head of the Communicable Diseases Control Programs, Ministry of Public Health, Doha, Qatar, and a doctoral candidate at the Erasmus Medical Centre. His research interests are mainly the epidemiology of MERS-CoV and spread of MERS-CoV at the human–animal interface.

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Acknowledgment

This work was supported by grants from the European Commission’s H2020 program under contract number 643476 (http://www.compare-europe.eu) and CRDF Global (project no. 61211/61210).

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References

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  2. So  RT, Perera  RA, Oladipo  JO, Chu  DK, Kuranga  SA, Chan  KH, et al. Lack of serological evidence of Middle East respiratory syndrome coronavirus infection in virus exposed camel abattoir workers in Nigeria, 2016. Euro Surveill. 2018;23. DOIPubMed
  3. Sikkema  RS, Farag  EABA, Islam  M, Atta  M, Reusken  CBEM, Al-Hajri  MM, et al. Global status of Middle East respiratory syndrome coronavirus in dromedary camels: a systematic review. Epidemiol Infect. 2019;147:e84. DOIPubMed
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  8. Corman  VM, Müller  MA, Costabel  U, Timm  J, Binger  T, Meyer  B, et al. Assays for laboratory confirmation of novel human coronavirus (hCoV-EMC) infections. Euro Surveill. 2012;17:20334. DOIPubMed
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  10. Kandeil  A, Gomaa  M, Shehata  M, El-Taweel  A, Kayed  AE, Abiadh  A, et al. Middle East respiratory syndrome coronavirus infection in non-camelid domestic mammals. Emerg Microbes Infect. 2019;8:1038. DOIPubMed

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Table

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Suggested citation for this article: Farag E, Sikkema RS, Mohamedani AA, de Bruin E, Munnink BBO, Chandler F, et al. MERS-CoV in camels but not camel handlers, Sudan, 2015 and 2017. Emerg Infect Dis. 2019 Dec [date cited]. https://doi.org/10.3201/eid2512.190882

DOI: 10.3201/eid2512.190882

Original Publication Date: 11/6/2019

1These first authors contributed equally to this article.

2These authors were co–principal investigators.

Table of Contents – Volume 25, Number 12—December 2019

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Samira Hamid Abd Elrahman, University of Gezira, Blue Nile National Institute for Communicable Diseases, PO Box 101, Wad Medani, Gezira, Sudan

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Page created: November 06, 2019
Page updated: November 06, 2019
Page reviewed: November 06, 2019
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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