MERS-COV (26): SAUDI ARABIA, ABATTOIR WORKERS (NIGERIA), PRIMARY CAMEL EXPOSURE

Posted on 19TH AUG 2018
tagged MERS-CoV, Nigeria

A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

In this update:
[1] Saudi Arabia (Al Bahah)
[2] MERS in camel workers: Eurosurveillance
[3] Review of camel exposure in reported cases: viruses

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[1] Saudi Arabia (Al Bahah)
Date: Fri 17 Aug 2018
Source: Saudi MOH 17 Aug 2018 [edited]
https://www.moh.gov.sa/en/CCC/events/national/Documents/Epiwk33.pdf

17 Aug 2018
New [case no.] 18-1740
MERS in Buljorshy: An 80-year-old male living in Buljorshy city, Albaha region.
Contact with camels: No
Case classification: Primary / community-acquired
Current Status: Hospitalized

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Communicated by:
ProMED-mail Rapporteur Mary Marshall

[This is the 1st newly confirmed case of MERS-CoV infection reported by Saudi Arabia since Sun 5 Aug 2018. It is difficult to discuss the case further in the absence of more details, other than to conclude it is classified as a primary case with community acquisition, in the absence of known direct (or indirect) camel contact.

The newly revised website does not provide information on outcomes of reported cases. One conclusion is that, in the absence of identified contact with camels or known other cases in the community, these cases are considered primary community-acquired cases.

Al Bahah is located in the south of Saudi Arabia surrounded on 3 sides by Makkah Province and bordering with Asir on its southeast borders. (http://ontheworldmap.com/saudi-arabia/administrative-divisions-map-of-sa...).

HealthMap/ProMED-mail map:
Saudi Arabia: http://healthmap.org/promed/p/131. - Mod.MPP]

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[2] MERS in camel workers: Eurosurveillance
Date: Thu 9 Aug 2018
Source: Eurosurveillance [edited]
https://eurosurveillance.org/content/10.2807/1560-7917.ES.2018.23.32.180...

[ref: So RT, Perera RA, Oladipo JO, 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(32). doi: 10.2807/1560-7917.ES.2018.23.32.1800175]
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Introduction
Middle East respiratory syndrome coronavirus (MERS-CoV) is an ongoing threat to global public health [1]. Serological and virological studies have shown evidence of MERS-CoV infection in camels in the Middle East, as well as in East, North, and West Africa [2-5] and in Central Asia [6]. In spite of MERS-CoV being enzootic in camels in Africa, zoonotic MERS has not been reported from the African continent. Our recent genetic and phenotypic analysis of MERS-CoV from camels in West (Burkina Faso, Nigeria) Africa has shown that West African viruses were phylogenetically and phenotypically distinct from those associated with human disease in the Arabian Peninsula [7], raising the possibility that virus strain differences may be associated with differences in zoonotic potential.

Abattoir workers with exposure to infected camels are a high-risk group for MERS-CoV infection in the Arabian Peninsula [8]. However, there is a paucity of serological data on MERS-CoV infection in people occupationally exposed to camels in Africa, a knowledge gap identified as a priority research question at a Food and Agriculture Organization of the United Nations-World Organisation for Animal Health-World Health Organization (FAO-OIE-WHO) Global Technical Meeting on MERS in September 2017 [1]. A previous study in Egypt in 2013 showed no serologic evidence of MERS-CoV among 179 serum samples from humans working in 2 camel abattoirs [3]. None of 760 people with household exposure to seropositive camels in Kenya in 2013 had evidence of MERS-CoV antibody [9]. Another study in Kenya in 2013-14 of 1122 people (not with necessarily high exposure to camels) found 2 sera with low and inconclusive levels of neutralising antibody to MERS-CoV [10]. It remains important to carry out more sero-epidemiological studies on humans with occupational exposure to infected camels to understand whether or not zoonotic transmission is taking place in Africa. We therefore investigated for serological evidence of MERS-CoV infection of humans occupationally exposed to infected dromedary camels in an abattoir in Kano, Nigeria.

Methods
Study sites and sample collection
Around 70 camels are slaughtered daily at the abattoir in Kano, Nigeria. We collected around 20 nasal swabs daily from [12 Oct 2015 to 2 Dec 2015] and from [11 Jan 2016 to 29 Feb 2016]. Swab samples were placed in viral transport medium and stored at -80 deg C/-112 deg F.

Abattoir workers with and without occupational exposure to camels were recruited for a serological study after obtaining informed consent, during April-November 2016. A questionnaire was administered to each participant to ascertain demographic information, type and duration of occupational exposure to camels or other livestock, practices such as consuming camel milk, or use of camel urine for food or health purposes. Camel exposures in the abattoir were classified as "direct" (exposure to live or freshly slaughtered camels or camel meat) or "indirect" (no exposure to live camels or freshly slaughtered camels or meat; exposure only being to cooked meat or dried bones, etc., as further described in the table). Duration of exposure to camels in the abattoir was categorised as less than one year, 1-5 years, or greater than 5 years. These workers used no personal protective equipment.

Virological and serological analysis
Total nucleic acid was extracted from camel nasal swabs using EasyMag (Biomerieux, France) and screened for MERS-CoV RNA using a reverse-transcription qPCR (RT-qPCR) assay targeting the upstream elements of the Envelope (UpE) gene. Positive samples were confirmed by testing with a 2nd RT-qPCR targeting the open reading frame 1a (ORF1a) gene [3,11].

Human sera were tested for MERS-CoV antibody using a MERS-CoV S1 spike enzyme-linked immunosorbent assay (ELISA; Euroimmun, Lubeck, Germany) according to manufacturer's instructions and by a pseudoparticle neutralisation (ppNT) assay as described previously [12]. A greater than or equal to 90 percent reduction of signal was considered as evidence of neutralisation in the ppNT assay.

Results
Overall, 2529 camels were tested, 38 of them being calves less than 2 years, 1400 aged 2-4 years, and 1091 aged greater than 4 years. None of the 1300 camels tested from [12 Oct 2015 to 2 Dec 2015] were positive for MERS-CoV RNA. Those tested in the week of [11 Jan 2016 (n = 142) remained virus RNA negative. MERS-CoV was detected in subsequent weeks, 5 (2.6percent) of 190 swabs in the week of [18 Jan 2016], 2 (1 percent) of 199 in the week of [25 Jan 2018], 12 (6.6 percent) of 183 in the week of [1 Feb 2016], 16 (8.4 percent) of 190 in the week of [8 Feb 2016], 12 (7.4 percent) of 162 in the week of [15 Feb 2016], and 8 (5.2 percent) of 155 in the week of [22 Feb 2016]. None of 8 tested in the week of [29 Feb 2016] were positive. Of the 2529 camels tested, MERS-CoV RNA was detected in 4 (10.5 percent) of 38 aged less than 2 years, 31 (2.2 percent) of 1400 aged 2-4 years and 20 (1.8 percent) of 1091 aged greater than 4 years.

A total of 311 abattoir workers were recruited for the serological study. Of these, 261 had occupational exposure to camels, with 243 workers having direct exposure to live camels, freshly killed camels, or camel meat and 18 having indirect exposure to camels. Fifty persons recruited in the study worked in the slaughterhouse with no occupational camel exposure. Many workers in the abattoir, including those without direct occupational exposure to camels, reported drinking fresh (unboiled) camel milk, drinking camel urine, using camel urine for medicinal purposes ([table available at source URL]). Irrespective of these modes of exposure, none of the 311 humans tested had any evidence of MERS-CoV antibody in their serum.

Table: Exposure to camels and history of camel product consumption in abattoir workers recruited for a Middle East respiratory syndrome coronavirus serological study, Kano, Nigeria, April-November 2016 (n = 311)

Discussion
Camels (n = 132) in this abattoir in Kano had been previously studied in January 2015, and MERS-CoV RNA was detected in 11 percent of samples, while 96 percent were antibody positive [2]. In 2016 (this study), virus RNA detection in January-February ranged from 0-8.4 percent of camels sampled. The peak period of MERS-CoV activity in Kano appeared to be in February, about 2 months later than the peak of virus activity previously reported in Egypt [13].

The high rates of virus detection in camels during January-February in 2015 and 2016 suggest that workers in the abattoir had prolonged and intensive occupational exposure to MERS-CoV-infected camels and camel carcasses, very likely over many years, without the use of any personal protective equipment. In addition to occupational exposure to camels in the slaughtering process, of the 50 workers in the abattoir with no occupational exposure to camels or camel meat (table) 15 reported frequent drinking of fresh camel milk, 10 drank fresh camel urine, and 10 used camel urine as medicine. The complete absence of MERS-CoV antibodies in workers is striking. Although the serological assays were carried out using the spike protein of the prototype MERS-CoV strain EMC, we have shown that MERS-CoV from diverse parts of Africa, including Nigeria/NS004/2015, do not differ antigenically from the prototype MERS-CoV EMC strain [7]. Thus antigenic diversity is unlikely to explain the lack of seropositivity observed in camel-exposed individuals in Nigeria. The MERS-spike protein pseudoparticle neutralisation assay has comparable sensitivity to plaque neutralisation tests in detecting antibody in humans infected with MERS-CoV [14].

MERS-CoV seroprevalence in persons with occupational exposure to camels in the Arabian Peninsula was significantly higher than in the general population; 5 (3.6 percent) of 140 workers occupationally exposed to camels in Saudi Arabia investigated in 2013-14 and 2 of 5 camel slaughterers in a central animal market in Qatar tested in 2014 were MERS-CoV seropositive [8,15]. Two of 22 camel barn workers at a camel race track in Qatar were seropositive [15]. In our study, of 261 workers exposed to camels in the abattoir in Kano, Nigeria, none were seropositive. This seropositivity rate is significantly lower than that of the camel abattoir workers in Saudi Arabia (p = 0.0049, Fisher's exact test) and that of the camel barn workers at a race track in Qatar (p = 0.0058). The finding of only negative test results in 113 camel slaughterers in this study yields a significantly different rate of seropositivity than that in camel slaughterers in an animal market in Qatar (p = 0.0014). Our results are concordant with that of a study in Kenya, East Africa, where there was no evidence of antibody in serum of 760 people with household or occupational exposure to MERS-CoV seropositive camels [9]. Another study of the general population from Kenya found evidence of neutralising MERS-CoV antibody at very low antibody titre in 2 of 1122 sera (0.18 percent) [10], comparable with a general population seroprevalence of 0.15 percent of sera from Saudi Arabia [8]. But it is unclear if these low antibody titres reflect actual infection with MERS-CoV. MERS-CoV from West Africa, including Nigeria, were genetically and phenotypically distinct from those in East Africa [7], and thus, zoonotic potential of viruses from Nigeria may be different from those in Kenya. Overall, these data may suggest that the risk of MERS infection from exposure to infected camels may be lower in some African countries.

It should be noted that seroconversion is not invariable even in patients with MERS. In a cohort of patients with RT-PCR-confirmed MERS in the South Korean outbreak in 2015 who were serologically followed up for one year, 4 of the 6 patients who had mild disease (i.e., did not require supplemental oxygen or mechanical ventilation) were negative by S1 ELISA, 2 were positive by plaque reduction neutralisation test (PRNT) 90 (titre 1:10), and of these 2, only one was positive by ppNT (titre of 10) [16]. Although designated as having mild disease, with one exception, these patients, had chest infiltrates on X-ray, indicating lung parenchymal pathology. In another cohort of South Korean MERS patients, none of 3 persons with asymptomatic infection and only 6 of 10 patients with symptomatic disease without pneumonia seroconverted, whereas most patients with severe pneumonia did seroconvert [17]. Therefore, it is possible that camel-exposed individuals who get asymptomatic or mild infections may not seroconvert. Even in those who do develop detectable antibody, waning antibody titres may lead to negative serological results. Thus sero-epidemiological studies may well underestimate the true extent of MERS-CoV infection in humans. A recent study showed that virus-specific CD8 + T-cell responses were detected in mild or asymptomatic patients with MERS-CoV infection, even in the absence of serologic responses [18]. T-cell responses and their specificity for MERS-CoV should also be investigated in future studies for identifying evidence of zoonotic MERS-CoV infection in high-risk groups.

In conclusion, we found no serological evidence of MERS-CoV infection in abattoir workers with extensive exposure to dromedaries with documented virus infection in winter months. lt is possible that MERS-CoV from West Africa may have lower zoonotic potential than current virus strains in the Arabian Peninsula [7]. Studying MERS-CoV in humans in Africa is an urgent priority. There is also a need for additional studies to genetically and phenotypically characterise MERS-CoV in Nigeria and other parts of Africa.

References available at source URL above.

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Communicated by:
ProMED-mail Rapporteur Mary Marshall

[In a nutshell, in spite of having documented exposure to the MERS-CoV infected animals, there were no identifiable seroconversions amongst abattoir workers in Nigeria, thereby highlighting the enigma of "Why Saudi Arabia?" - Mod.MPP]

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[3] Review of camel exposure in reported cases: viruses
Date: Tue 14 Aug 2018
Source: Viruses [edited]
http://www.mdpi.com/1999-4915/10/8/425/htm

[ref: Conzade R, Grant R, Malik M, et al. Reported direct and indirect contact with dromedary camels among laboratory-confirmed MERS-CoV cases. Viruses. 2018; 10(8). pii: E425. doi: 10.3390/v10080425]
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Abstract
Dromedary camels (_Camelus dromedarius_) are now known to be the vertebrate animal reservoir that intermittently transmits the Middle East respiratory syndrome coronavirus (MERS-CoV) to humans. Yet, details as to the specific mechanism(s) of zoonotic transmission from dromedaries to humans remain unclear. The aim of this study was to describe direct and indirect contact with dromedaries among all cases, and then separately for primary, non-primary, and unclassified cases of laboratory-confirmed MERS-CoV reported to the World Health Organization (WHO) between 1 January 2015 and 13 April 2018. We present any reported dromedary contact: direct, indirect, and type of indirect contact. Of all 1125 laboratory-confirmed MERS-CoV cases reported to WHO during the time period, there were 348 (30.9 percent) primary cases, 455 (40.4 percent) non-primary cases, and 322 (28.6 percent) unclassified cases. Among primary cases, 191 (54.9 percent) reported contact with dromedaries: 164 (47.1 percent) reported direct contact, 155 (44.5 percent) reported indirect contact. Five (1.1 percent) non-primary cases also reported contact with dromedaries. Overall, unpasteurized milk was the most frequent type of dromedary product consumed. Among cases for whom exposure was systematically collected and reported to WHO, contact with dromedaries or dromedary products has played an important role in zoonotic transmission.

[I've excerpted the discussion and conclusion sections. Interested readers are pointed to the source URL for the full article, including helpful tables supporting the conclusions and observations below. - Mod.MPP]

4. Discussion
This is the first study to describe contact among all MERS-CoV infections reported to WHO with the known animal reservoir of MERS-CoV: dromedary camels. We report that among all of the 1125 MERS-CoV cases reported to WHO between 1 January 2015 and 13 April 2018, 30.9 percent were primary cases. Among primary cases, 191 (54.9 percent) reported direct or indirect contact with dromedaries, 164 (47.1 percent) reported direct, physical, contact with dromedaries, and 155 (44.5 percent) reported contact with products derived from dromedaries, namely unpasteurized camel milk.

We found primary human cases more likely to be older, with a higher proportion of males compared to all cases, and compared to non-primary or unclassified cases. This likely reflects differences in cultural practices and exposures to dromedaries between men and women in the Middle East, rather than a difference in infection susceptibility. In this study, all primary MERS-CoV infections have occurred in countries in the Middle East, including KSA, which accounts for 96.3 percent of primary infections reported between 1 January 2015 and 13 April 2018 (table 1). In this region, dromedary ownership, herding, and farming practices have increased in recent decades, and camel farms are increasingly concentrated close to major cities, with camel workers often living inside or in close proximity to camel barns. As culturally important animals, dromedaries are celebrated in camel races, sales, beauty competitions, and parades, and often kissed, hugged, and greeted, intensifying frequency of direct contact with dromedaries [23,24,39,43]. In addition, unpasteurized camel milk and meat are widely consumed, despite current WHO recommendations for people living in areas with reported MERS-CoV circulation to avoid drinking raw camel milk [44], and camel urine, which is believed to have therapeutic benefits. The risk of MERS-CoV infection from the consumption of unpasteurized camel milk has been evaluated in Qatar, and the authors found evidence of MERS-CoV RNA and neutralizing antibodies in the milk but could not determine if MERS-CoV was in the milk or contaminated during the milking process [35].

Although it is clear that contact with infected dromedaries are the primary source of recurrent introduction of MERS-CoV into the human population, mitigating spillover from dromedaries to humans has been limited by a lack of clarity on the modes of transmission between dromedaries and humans, the extent of spillover to humans, and the epidemiology of MERS-CoV circulation in dromedaries in large parts of Africa and South Asia. A deeper understanding of why zoonotic transmission has been undetected in many countries in Africa, the Middle East (outside the Arabian Peninsula), and South Asia, despite high seroprevalence in dromedaries in such countries, is required [45]. WHO, the Food and Agriculture Organization of the United Nations (FAO), in collaboration with technical partners in these regions, are currently working to implement field studies at the animal/human interface, to further understand the extent of circulation in dromedaries, zoonotic transmission, dromedary husbandry practices, and trade patterns of dromedaries in a number of countries across Africa and South Asia (personal communication, with permission, Van Kerkhove).

Our study applied a One Health vision to retrospective analysis of epidemiological data to determine if we could better understand infection at the animal/human interface. The findings show clearly that contact with dromedaries has likely played an important role in the continued introduction of MERS-CoV into the human population from the dromedary camel reservoir. While there have been notable improvements in surveillance and reporting of human cases since 2015, multidisciplinary research, cross-sectoral collaboration at country level, public awareness about the disease, and laboratory and surveillance capacity in affected countries, particularly since 2015, there is still a need to further understand frequency and patterns of contact between infected dromedaries and humans that lead to zoonotic transmission, best achieved through multisite anthropological studies in areas across which MERS-CoV is known to circulate, not only in human populations, but also in dromedary populations. Interrupting zoonotic transmission could also be achieved through the ongoing development and application of dromedary and/or human vaccine candidates.

The results of our study are strengthened by the size of the study, which includes all laboratory confirmed cases reported to WHO since [1 Jan 2015]. We were not able include all laboratory confirmed cases reported to WHO since 2012, because prior to 2015, there were inconsistencies in the way exposure information for each human MERS-CoV infection was collected. For example, at the start of this epidemic in 2012, a comprehensive data collection tool was not used by all countries identifying MERS cases and potential risk factor data, and disease/outcome information about individual patients after the time of reporting was not systematically reported to WHO. Even among data reported since 2015, there is some missing data for contact with dromedaries and there is a complete absence of information on the use of personal protective equipment (PPE; e.g., gloves, boots, coveralls, masks/respirators) when in direct contact with dromedaries, and on hygiene practices following contact with dromedaries. This limits our ability to draw conclusions from our dataset, as to how each case was infected and the exact route(s) of transmission. The use of PPE, however, has been evaluated in a detailed case-control study in Qatar evaluating specific types of dromedary contact among seropositive vs seronegative occupational workers, which found that hand washing before and after contact with the dromedary was protective against infection with MERS-CoV [46].

Our dataset is also limited by our ability in classifying cases based on available information reported to WHO at the time of reporting by the country. For example, thorough outbreak investigations, which include full genome sequencing of the virus, may find that cases which were initially classified as non-primary cases, may in fact be primary cases, and this information was not regularly relayed to WHO. More complete case reporting, including exposures prior to symptom onset, would improve our ability to assess non-human exposures that may have led to primary MERS illness in humans. Efforts are currently being made to retrospectively review and update the epidemiological data for all cases reported to WHO to date, particularly prior to 2015. To aid member states in more systematic data collection on suspected and confirmed MERS cases, WHO has updated guidance on investigation of cases, and has revised the MERS case reporting forms, which include specific questions about contact with known MERS patients, healthcare visits, travel, occupation, dromedary contact, other animal contact, and underlying medical conditions within the 14 days prior to symptom onset [47,48].

5. Conclusions
In conclusion, a lack of systematic reporting on exposures and risk factors, including contact with dromedaries for each MERS case identified since 2012, prevents a clear understanding of how infection occurred in each case. However, it is clear from the data reported that contact with dromedaries has played an important role in transmission of MERS-CoV into the human population from the dromedary reservoir. As a result, further understanding the geographic scope of MERS-CoV circulation in dromedaries, and limiting direct and indirect contact with infected dromedaries, remains important for reducing zoonotic transmission of MERS-CoV.

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Communicated by:
ProMED-mail Rapporteur Mary Marshall

[As I have said before, why Saudi Arabia? Why are the overwhelming majority of cases reported from Saudi Arabia? What also awaits addressing is what are the routes of transmission for the primary community-acquired cases with no identifiable known contact with camels. - Mod.MPP]

See Also
MERS-CoV (25): risk assessment, WHO 20180808.5954813
MERS-CoV (24): Saudi Arabia, MoH reports 20180807.5950858
MERS-CoV (23): Saudi Arabia, WHO, RFI 20180711.5899938
MERS-CoV (22): Saudi Arabia, WHO 20180629.5862285
MERS-CoV (21): EMRO/WHO update May 2018 20180612.5852927
MERS-CoV (20): Saudi Arabia (NJ) susp. family cluster 20180602.5835120
MERS-CoV (10): Oman, Saudi Arabia, WHO 20180315.5690014
MERS-CoV (01): Malaysia (ex KSA), Saudi Arabia, UAE (ex Oman) 20180102.5532148
2017
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MERS-CoV (77): Saudi Arabia, camels, human, epidemiology, assessment 20171222.5520561
MERS-CoV (01): Saudi Arabia (QS, RI, MD) RFI 20170105.4744802
2016
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MERS-CoV (123): Saudi Arabia (MK, AS) new cases 20161231.4734758
MERS-COV (01): Oman, Saudi Arabia 20160105.3911188
2015
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MERS-COV (167): acute management and long-term survival 20151231.3904300
MERS-CoV (01): Saudi Arabia, new cases, new death 20150104.3069383
2014
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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
2013
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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
2012
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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
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