Elimination of the Corona virus by straw-colored fruit bats in Africa with possible transmission of zoonotic pathogens

In a recent study published in the journal, PLUS ONEIn the study, researchers assessed the temporal precipitation patterns of coronavirus (CoV) in Eidolon HellStraw-colored fruit bat.

E. helvum It is a type of petropod that is widespread in tropical Africa and can migrate for thousands of kilometers; They roost in trees to form dynamic colonies, hosting millions. The bat is a unique seed distributor due to its migration. As such, the save E. helvum It is critical to tropical Africa. These species have adapted to habitat loss by roosting in trees across urban areas. This potentially exposes humans to the secretions of bats and the disease-causing species that shed in them.

Studies in urban and non-urban bat colonies have reported viral nucleic acids and multiple virus isolations from diverse taxonomic families. The family Coronaviridae was previously discovered in this species. However, the disposal patterns of MERS-CoV in this species of bat are still poorly defined, and in general, there is a lack of understanding of MERS-CoV ecology in African bats.

Stady: Seasonal elimination of coronavirus by straw-colored fruit bats in urban roosts in Africa. Image Credit: Ondrej Prosicky / Shutterstock

about studying

In this study, researchers investigated the patterns of CoV secretion in E. helvum Perched to propose realistic strategies that support a safer, ethical coexistence of this species with humans. They studied two urban colonies of this type of bat, located in Accra, Ghana, and Morogoro, Tanzania. The colony was studied in Accra between March 2017 and February 2018, while the Morogoro perch was studied from August 2017 to July 2018.

The number of bats per roost was counted monthly. Ninety-seven stool samples were collected monthly from each roost. RNA was extracted from 2328 fecal samples, and cDNA libraries were prepared. Two polymerase chain reaction (PCR) assays were used to identify known and novel CoVs. The amplified products were cloned and sequenced. A baseline search was performed on the Local Alignment Search Tool (BLAST) to compare sequences with those of CoV genes.

The reproductive cycle of bats was estimated based on 1) the authors’ previous data from Accra and Morogoro, 2) previous observations from roosts, 3) reporting of the birth pulse and lactation period, 4) the synchronous annual birth pulse for this species, and 5) heterogeneity in gestational time and estrus The birth pulse. The beginning of the lactation period, the end of the birth pulse and the beginning of the weaning period were supposed to be 15 April, 15 June and 16 June respectively in Accra.

In Morogoro, the team set December 15 as the start of the lactation period, and February 15 and 16 as the last date for the birth pulse, and the start of the weaning period. Track the remainder of the year immediately after these time points. The relationship between CoV shedding and reproductive cycle was evaluated using two logistic models (fixed effects and hierarchical models).

Panel (a) shows the locations of roosts in Africa.  Panel B shows some trees occupied at the 37th Military Hospital in Accra, Ghana, and Panel C shows bats roosting at Kikundi Market in Morogoro, Tanzania.

Panel (a) shows the locations of roosts in Africa. Panel B shows some trees occupied at the 37th Military Hospital in Accra, Ghana, and Panel C shows bats roosting at Kikundi Market in Morogoro, Tanzania.

the findings

The Morogoro bat colony reached its peak in February 2018, with a population of 45,000, while Accra’s population peaked in December 2017 at over 1 million. Fourteen stool samples from Accra and 125 samples from Morogoro tested positive for coronaviruses. The monthly proportion of positive stool samples was variable and peaked at 0.24 in Morogoro and 0.04 in Accra.

The proportion of positive samples during the lactation and weaning periods was 0 and 0.018 in Accra and 0.088 and 0.153 in Morogoro, respectively. BLAST analyzes revealed that all CoVs identified in the current study showed a pairwise sequence identified with Eidolon bat CoV of the genus Beta-CoV.

According to the fixed effects model, the odds of a coronavirus outbreak were 1.24 to 2.65 times higher than for the remainder of the year. Compared to the lactation period, the weaning period had 1.06 to 3.16-fold higher odds of precipitating CoV. The hierarchical model showed increased odds of CoV precipitation in the later months of the weaning period compared to the rest of the year. In addition, the odds of shedding MERS-CoV during the peak weaning period increased compared to the period of infancy.

Conclusions

In summary, viruses detected in bat fecal samples from roosters had high sequence identity with Eidolon bat CoV. There was no evidence to suggest that CoVs detected in roosts pose a public health threat unless proven otherwise. The results support the seasonal fall pattern of coronaviruses in both groups, with peaks occurring during the weaning season.

Overall, the results suggest that resources to prevent human-bat contact should be directed to use in weaning seasons and to limit human access to roosts and adjacent areas. Additionally, bat consumption should generally be discouraged, and hunting/selling should be prohibited seasonally. These recommendations to reduce human exposure to bats apply to everyone E. helvum Perched all over Africa.