Posted on 01ST APR 2017
tagged MERS-CoV, Africa

A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Thu 30 Mar 2017
Source: Eurosurveillance, Volume 22, Issue 13 [edited]

Research article: Risk factors for MERS Coronavirus infection in dromedary camels in Burkina Faso, Ethiopia and Morocco, 2015
Miguel E, Chevalier V, Ayelet G, et al.

Understanding Middle East respiratory syndrome coronavirus (MERS-CoV) transmission in dromedary camels is important, as they constitute a source of zoonotic infection to humans. To identify risk factors for MERS-CoV infection in camels bred in diverse conditions in Burkina Faso, Ethiopia and Morocco, blood samples and nasal swabs were sampled in February-March 2015. A relatively high MERS-CoV RNA rate was detected in Ethiopia (up to 15.7 percent; 95 percent confidence interval (CI): 8.2-28.0), followed by Burkina Faso (up to 12.2 percent; 95 percent CI: 7-20.4) and Morocco (up to 7.6 percent; 95 percent CI: 1.9-26.1). The RNA detection rate was higher in camels bred for milk or meat than in camels for transport (p = 0.01) as well as in younger camels (p = 0.06). High seropositivity rates (up to 100 percent; 95 percent CI: 100-100 and 99.4 percent; 95 percent CI: 95.4-99.9) were found in Morocco and Ethiopia, followed by Burkina Faso (up to 84.6 percent; 95 percent CI: 77.2-89.9). Seropositivity rates were higher in large/medium herds (greater than or equal to 51 camels) than small herds (p = 0.061), in camels raised for meat or milk than for transport (p = 0.01), and in nomadic or sedentary herds than in herds with a mix of these lifestyles (p less than 0.005).

Authors: E Miguel, V Chevalier, G Ayelet, MN Ben Bencheikh, H Boussini, DK Chu, I El Berbri, O Fassi-Fihri, B Faye, G Fekadu, V Grosbois, BC Ng, RA Perera, T So, A Traore, F Roger, M Peiris.

Communicated by:

[The published report of the international research project is a timely effort to decipher the MERS enigma, namely the scarcity, or apparent absence, of human MERS cases in countries outside the Arabian Peninsula in spite of serologically demonstrated evidence of the corona virus activity in their respective dromedary camel populations. Such situation has been recorded also in other countries (eg, Israel). Even within the Arabian peninsula, there are still numerous primary cases in which the source of infection could not be demonstrated.

The following excerpts from the discussion section of the above research paper include some interesting observations (for the mentioned tables and references, please refer to the full paper at the source URL):

"There is an apparent gradient of virus RNA positivity adjusted for age (Table 3) from west to east which could be explained by a gradient in camel density (Figure 1A), in addition to other drivers such as climate, migratory roads and national and international camel exchanges. Since Ethiopia is a main exporter to the Arabian Peninsula through 2 main ports in Djibouti and Somalia [35], the virus transmission dynamics in this region is of particular interest.

We observed an increase in seropositivity rate with age which confirms the trend observed in Ethiopia in a previous study [20]. We found a higher virus RNA detection rate in young animals compared with older animals which could be related to a lack of prior immunity as published in previous studies in Saudi Arabia [36]. Young animals were naive and more susceptible to virus infection". ------

----- "Camels raised for milking (which are females) show the highest serological prevalence followed by camels raised for their meat (which are mostly males) and lastly, camels used for transport activities (which are also mostly males), which have the lowest seroprevalence (Table 3 and model selection). The higher seropositivity rate in females bred for milking could be related to the high viral RNA detection rates in younger animals, e.g. calves [37]. A plausible hypothesis could indeed be that young camels who lack antibodies have a high probability of being infected and in turn expose the mothers to infection or reinfection. The lower seropositivity rate in camels bred for their meat or for transport activities, which are mostly males, could also be linked with the fact that males are often separated from the herd (the 2 sexes are only mixed during the reproduction activities) and have thus less contacts with other camels (i.e. females and calves)".

As indicated in the paper, the survey was limited to a narrow period in time, February-March 2015, and does not provide insights into seasonal variation in epidemiological dynamics. Hopefully, research efforts addressing the One Health aspects of MERS and its epidemiology, within and beyond the Arabian peninsula, will gain support and be forcefully continued. - Mod.AS

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See Also

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MERS-CoV (59): animal reservoir, review 20160610.4275921
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MERS-CoV (39): Saudi Arabia (RI) 20160315.4095267
MERS-CoV (38): Saudi Arabia (RI, MK), RFI 20160314.4092319
MERS-CoV (37): Saudi Arabia (QS, HA) 20160313.4090021
MERS-CoV (36): Saudi Arabia, RFI 20160312.4088330
MERS-CoV (35): Saudi Arabia, Qatar ex Saudi Arabia, WHO 20160311.4085518
MERS-CoV (34): Saudi Arabia, nosocomial, RFI 20160310.4083896
MERS-CoV (33): Saudi Arabia, nosocomial 20160309.4076391
MERS-CoV (32): Saudi Arabia (RI) 20160306.4072878
MERS-CoV (31): Saudi Arabia, Kenya serosurvey 20160305.4070643
MERS-CoV (30): Saudi Arabia (QS) WHO 20160303.4066494
MERS-CoV (29): Saudi Arabia (RI) 20160229.4057451
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MERS-CoV (27): Saudi Arabia (RI), RFI 20160226.4053654
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MERS-CoV (25): Saudi Arabia, RFI 20160223.4045089
MERS-CoV (24): Qatar ex Saudi Arabia, Saudi Arabia (RI) RFI 20160222.4041719
MERS-CoV (23): Saudi Arabia (RI) 2015 outbreak, RFI 20160220.4036190
MERS-CoV (22): Saudi Arabia (RI) RFI 20160218.4028850
MERS CoV (21): Saudi Arabia, animal reservoir, camel, comment 20160216.4023772
MERS-CoV (20): Saudi Arabia (NJ,RI) 20160212.4016509
MERS CoV (19): Saudi Arabia, animal reservoir, camel, prevention, RFI 20160204.3995194
MERS-CoV (18): Saudi Arabia, animal reservoir, camel, vaccination, comment 20160203.3990284
MERS-CoV (17): Saudi Arabia (MK) WHO 20160203.3987728
MERS-CoV (16): Saudi Arabia (MK) animal reservoir, OIE, RFI 20160201.3985175
MERS-CoV (15): Saudi Arabia (RI) 20160201.3985046
MERS-CoV (13): Saudi Arabia (RI) 20160127.3970964
MERS-CoV (12): UAE, Oman, Saudi Arabia, WHO 20160126.3967808
MERS-CoV (11): Saudi Arabia, animal reservoir, camel, vaccination, comment 20160126.3966528
MERS-CoV (10): Saudi Arabia (MK), Thailand ex Oman, RFI 20160125.3964309
MERS-CoV (09): Saudi Arabia, animal reservoir, camel, vaccination considered 20160125.3963370
MERS-COV (08): Thailand ex Oman, Saudi Arabia corr 20160124.3962172
MERS-CoV (07): Saudi Arabia 20160123.3959982
MERS-CoV (06): UAE (AZ) 20160114.3937314
MERS-COV (03): Korea, virus mutation 20160108.3921223
MERS-COV (01): Oman, Saudi Arabia 20160105.3911188
MERS-COV (167): acute management and long-term survival 20151231.3904300
MERS-CoV (01): Saudi Arabia, new cases, new death 20150104.3069383
MERS-CoV (69): Saudi Arabia, new case, RFI 20141230.306305
MERS-CoV (01): Bangladesh, KSA, Algeria, UAE, Iran, WHO, RFI 20140616.2541707
MERS-CoV - Eastern Mediterranean (82): anim res, camel, seroepidemiology 20140613.2537848
MERS-CoV - Eastern Mediterranean (01): Saudi Arabia, UAE, Oman, WHO 20140103.2150717
MERS-CoV - Eastern Mediterranean (106): animal reservoir, camel, Qatar, OIE 20131231.2145606
MERS-CoV - Eastern Mediterranean: Saudi Arabia, new case, RFI 20130518.1721601
Novel coronavirus - Eastern Mediterranean (29): MERS-CoV, ICTV nomenclature 20130516.1717833
Novel coronavirus - Eastern Mediterranean: bat reservoir 20130122.1508656
Novel coronavirus - Eastern Mediterranean (06): comments 20121225.1468821
Novel coronavirus - Eastern Mediterranean: WHO, Jordan, conf., RFI 20121130.1432498
Novel coronavirus - Saudi Arabia (18): WHO, new cases, cluster 20121123.1421664
Novel coronavirus - Saudi Arabia: human isolate 20120920.1302733