Cross-sectional prevalence study of MERS-CoV in local and imported dromedary camels in Saudi Arabia, 2016-2018

Abstract

The Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) is an endemic virus in dromedaries. Annually, Saudi Arabia imports thousands of camels from the Horn of Africa, yet the epidemiology of MERS-CoV in these animals is largely unknown. Here, MERS-CoV prevalence was compared in imported African camels and their local counterparts. A total of 1399 paired sera and nasal swabs were collected from camels between 2016 and 2018. Imported animals from Sudan (n = 829) and Djibouti (n = 328) were sampled on incoming ships at Jeddah Islamic seaport before unloading, and local camels were sampled from Jeddah (n = 242). Samples were screened for neutralizing antibodies (nAbs) and MERS-CoV viral RNA. The overall seroprevalence was 92.7% and RNA detection rate was 17.2%. Imported camels had higher seroprevalence compared to resident herds (93.8% vs 87.6%, p <0.01) in contrast to RNA detection (13.3% vs 35.5%, p <0.0001). Seroprevalence significantly increased with age (p<0.0001) and viral RNA detection rate was~2-folds higher in camels <2-year-old compared to older animals. RNA detection was higher in males verses females (24.3% vs 12.6%, p<0.0001) but seroprevalence was similar. Concurrent positivity for viral RNA and nAbs was found in >87% of the RNA positive animals, increased with age and was sex-dependent. Importantly, reduced viral RNA load was positively correlated with nAb titers. Our data confirm the widespread of MERS-CoV in imported and domestic camels in Saudi Arabia and highlight the need for continuous active surveillance and better prevention measures. Further studies are also warranted to understand camels correlates of protection for proper vaccine development.

Limited Genetic Diversity Detected in Middle East Respiratory Syndrome-Related Coronavirus Variants Circulating in Dromedary Camels in Jordan

“…MERS-CoV genome sequences described by Chu et al revealed discrete regional patterns of genetic diversity in Africa [ 15 ], suggesting structured populations of MERS-CoV circulating in African camel herds. A recent study reported a high incidence of MERS-CoV RNA detected in camels from eastern Africa on import vessels destined for markets in Saudi Arabia, likely providing an opportunity for mixing between previously geographically isolated lineages [ 19 ]. Consistent with these observations, studies have shown extensive recombination between MERS-CoV lineages in the large camel markets of KSA and UAE [ 2 , 3 ].…”

MERS-CoV Confirmation among 6,873 suspected persons and relevant Epidemiologic and Clinical Features, Saudi Arabia — 2014 to 2019

“…Further, the high prevalence of metabolic diseases -related pathophysiology in men [ 14 , 34 , 35 , 40 , 41 ] predisposes them to the expression of MERS-CoV disease. KSA has the 4 th largest camel to population ratio (1 to 40 persons) after Somalia, Mauritania (1 to 1.4) and Sudan (1 to 8.6) [ 39 , 48 ]. The prevalence of diabetes in these countries with high per-capita camel population (Mauritania 6.7%, Somalia 5.1%, Sudan 7.7%) is however substantially lower than that of Saudi Arabia and may not provide sufficient susceptible population to cause large outbreaks [ 48 , 49 ].…”

“…KSA has the 4 th largest camel to population ratio (1 to 40 persons) after Somalia, Mauritania (1 to 1.4) and Sudan (1 to 8.6) [ 39 , 48 ]. The prevalence of diabetes in these countries with high per-capita camel population (Mauritania 6.7%, Somalia 5.1%, Sudan 7.7%) is however substantially lower than that of Saudi Arabia and may not provide sufficient susceptible population to cause large outbreaks [ 48 , 49 ]. The most recent seroprevalence of MERS-CoV among camels in Saudi Arabia was 92.7% and RNA detection rate was 17.2%, with some variation between imported and resident herds, but RNA detection was as high as 35.5% among resident camel herds than imported [ 11 , 29 , 48 , 49 ].…”

“…The prevalence of diabetes in these countries with high per-capita camel population (Mauritania 6.7%, Somalia 5.1%, Sudan 7.7%) is however substantially lower than that of Saudi Arabia and may not provide sufficient susceptible population to cause large outbreaks [ 48 , 49 ]. The most recent seroprevalence of MERS-CoV among camels in Saudi Arabia was 92.7% and RNA detection rate was 17.2%, with some variation between imported and resident herds, but RNA detection was as high as 35.5% among resident camel herds than imported [ 11 , 29 , 48 , 49 ]. Therefore, it appears the confluence of three factors- presence of a highly susceptible population notably with metabolic syndrome conditions, high MERS-CoV burden among the host, and sufficient interaction between with the host and susceptible population —should be met for efficient and extensive transmission of MERS-CoV [ 38 , 50 ].…”

High MERS-CoV seropositivity associated with camel herd profile, husbandry practices and household socio-demographic characteristics in Northern Kenya

“…A longitudinal study in Egypt reported the virus spread to >90% of a herd within two months, followed by a rapid decline in antibodies following the end of the outbreak to suggest that multiple re-infections of herds can occur within a short period [18]. Younger camels are particularly susceptible to MERS-CoV infection when compared with older ones, shed more virus and could drive infections in camel herds [20]. The Horn of Africa, including Kenya, Sudan, Ethiopia, and Somalia, is home to over 70% of the global dromedary camels population, and camel movement from the region to the Arabian Peninsula exceeds 300000 animals every year through trade [21,22].…”