Two teenagers killed in collapse at Sierra Leone gold mine.

Two teenagers have died in a pit collapse at an artisanal mine in Eastern Province, Sierra Leone. Mohamed Bangura (16) and Yahyah Janneh (17), from the village of Nyimbadu, had skipped school to work at the mine, one of the few ways to own a cash income in the remote village. Yahyah Janneh's mother, Namina, admits to having encouraged her son to mine gold, as a widow needing the extra income to help support her other children, but says that she would not have wanted him to go to the pit where he was killed, as this was known to be dangerous.

Yahyah Janneh (17), killed in a mine collapse in Eastern Province, Sierra Leone, in December 2025. Namina Jenneh/BBC.

The incident comes at the height of the West African rainy season, which often causes problems in Sierra Leone. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. However the situation has been made worse in Sierra Leone since the civil war of the 1990s, since when the country has effectively been bankrupt and unable to invest in maintenance of roads or infrastructure, despite being one of the most mineral rich countries of Africa.

The government of Sierra Leone has made the decision to invest heavily in education, seeing it as a way to provide people with a means to improve their own situations, and of creating a workforce able to help address the country's many problems. It currently spends about 8.9% of GDP on education, compared to an average of about 3.5% of GDP across the West and Central Africa regions, 5.59% in the US, 4.1% in the UK, and 4.7% in the EU. However, because of Sierra Leone's low GDP, this does mean that the amount spent on education per child is lower than in many African countries. Sierra Leone spent 34% of its domestic budget on education and 52.41% on debt servicing in 2023, the last year for which statistics are available.

Keeping children in school presents an additional challenge; many rural communities in Sierra Leone are dependent on subsistence farming, which provides little or no cash income, while working in artisanal mines can produce an income of around US$3.50 per week (less than half the theoretical minimum wage for Sierra Leone), with the potential for occasional bonanzas producing tens of dollars at a time. Against this background, many children (and some teachers) chose to skip school to work in minefields, repeating the country's cycle of poor educational achievement and subsequent low incomes.

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Marburg Virus detected in Egyptian Rousette Bat populations in Sierra Leone.

Marburg Virus, a close relative of the better-known Ebola Virus, is the founding member of the family Filoviridae, and is known to cause sporadic outbreaks of severe, often fatal disease in Humans. There have been 12 known Marburg Virus disease outbreaks, most recently in 2017 in Uganda. The largest Marburg Virus disease outbreak on record occurred in Uige, Angola, in 2005, with 227 deaths out of 252 known cases. This was the highest case-fatality ratio (90%) recorded for any large Filovirus outbreak, including the 2013–2016 Ebola Virus outbreak in West Africa (41%). A direct link to Marburg Virus spillover from Bats was not made during the event in Angola. Consistent with the high case-fatality ratio during the outbreak in Angola, the Marburg Virus Angola strain appears to be significantly more virulent than all other Marburg Virus strains (Musoke, Ravn, and Ozolin) in experimentally infected non-Human Primates. The Angola outbreak was the only Marburg Virus outbreak to originate outside of East Africa; all previous Marburg Virus disease outbreaks occurred in, or originated from, Uganda, Kenya, Democratic Republic of the Congo, or South Africa and Zimbabwe. Other Filoviruses circulating in Africa include the Marburgvirus, Ravn Virus, as well as five Ebolaviruses, Sudan Virus, Tai Forest Virus, Bundibugyo Virus, and the recently discovered Bombali Virus.

 

Negative stained transmission electron micrograph of a number of filamentous Marburg Virions, which had been cultured on Vero cell cultures, and purified on sucrose, rate-zonal gradients. Erskine Palmer/Russell Regnery/Centers for Disease Control and Prevention/Wikimedia Commons.

Extensive field studies in Uganda, Democratic Republic of the Congo, Kenya, South Africa, Gabon, and Zambia, as well as experimental infection studies in captive bats in the United States, have shown that the cave-dwelling Egyptian Rousette Bat, Rousettus aegyptiacus, is a primary natural reservoir of Marburg Virus. This discovery is consistent with the origins of Marburg Virus diseas outbreaks that, when known, have been linked to caves or mines, with Marburg Virus most often having spilled over to miners who work underground in known Egyptian Rousette Bat roosting sites, and occasionally to tourists who viewed Egyptian Rousette Bats too closely. Infected Egyptian Rousette Bats shed Marburg Virus in saliva and urine, and the Virus can persist for weeks in various tissues, particularly liver, spleen, and lymph nodes. Under experimental conditions, Marburg Virus can be transmitted directly between Egyptian Rousette Bats in the absence of Arthropod vectors. Furthermore, some infected Bats appear to be supershedders, capable of shedding a disproportionate amount of Virus, leading to increased Bat-Bat transmission in accordance with the Pareto principle. To date, Arthropod vectors do not appear to contribute to natural enzootic transmission of Marburg Virus among Egyptian Rousette Bats.

In equatorial Africa, Egyptian Rousette Bats live in very large, dense colonies sometimes numbering over 100 000 Bats. They can breed twice a year, producing thousands of susceptible juvenile Bats every six months in a single Egyptian Rousette Bats roost. Field studies in Uganda showed that 2–3% of all Egyptian Rousette Bats are actively infected with Marburgviruses (Marburg Virus and Ravn Virus) at any one time and that infection levels spike biannually, up to 12% on average, in juvenile Bats. Importantly, these seasonal spikes appear to be associated with increased risk of Human exposure, as they coincide with over 84% of known Marburg Virus spillover events to Humans. Despite the linkage of Egyptian Rousette Bats to Human Marburg Virus outbreaks, attempts to mitigate risk through Bat extermination were counterproductive and led to increased levels of active Marburg Virus infection in the recolonising Bat population.

 

A colony of Egyptian Rousette Bats, Rousettus aegyptiacus. Giovanni Mari/Flikr/iNaturalist.

Since 2007, over 80 distinct Marburg Virus genomic sequences and 21 Virus isolates have been obtained from tissues of infected wild-caught Egyptian Rousette Bats, representing every major Marburg Virus strain found in Marburg Virus disease outbreaks since 1967, with the exception of the Angola strain. In Gabon, South Africa and Zambia, Marburg Virus was detected in Egyptian Rousette Bats despite no known associated Human Marburg Virus disease outbreaks in the country. 

In a paper published in the journal Nature Communications on 24 January 2020, a team of scientists led by Brian Amman of the Viral Special Pathogens Branch of the Centers for Disease Control and Prevention report the presence of Marburg Virus, including an Angola-like Marburg Virus, in Egyptian Rousette Bats in Sierra Leone, West Africa.

Importantly, no Marburg Virus disease outbreaks have been reported in Sierra Leone despite the presence of Marburg Virus. Amman et al.'s findings highlight the value of engaging with all stakeholders with appropriate messaging that identify and mitigate pathogens of public health concern before recognized spillovers occur. This is in consonant with measures that ensure Animal and environmental health. Moreover, it underpins the One Health surveillance approach that recognizes the interconnected relationship between  people and other organisms (Plants and Animals) in a shared environment.

A total of 1755 Bats from 42 species were captured and sampled from 4 districts in Sierra Leone: Moyamba (Kasewe Cave), Kailahun (Tailu Village), Koinadugu (Kakoya Cave), and Kono (Koema Cave). All Bat samples were tested for 5 Filoviruses (Ebola Virus, Tai Forest Virus, Bundibugyo, Marburg Virus, and Ravn Virus). Of these, 435 Bats were identified as Egyptian Rousette Bats (186 from Kasewe Cave; 7 from Tailu Village; 131 from Kakoya Cave; and 111 from Koema Cave), from which 11 bats (2.5%) tested positive for active Marburg Virus infection by Virus-specific real-time reverse transcription polymerase chain reaction or consensus reverse transcription polymerase chain reaction. Marburg Virus-positive samples included six liver/spleen, five lymph nodes, two oral swabs, one salivary gland, and one whole blood sample. Marburg Virus isolation was attempted on all polymerase chain reaction positive tissues (13) and swabs (2), and from those, four Virus isolates were obtained from three Egyptian Rousette Bats caught at Kasewe Cave. Two Marburg Virus isolates were obtained from one Bat (no. 960), one from the liver/spleen and the other from lymph node, while one isolate was obtained from two other Bats (nos. 968 and 1000), each from liver/spleen. Owing to a non-destructive sampling protocol, tissue specimens from Egyptian Rousette Bats captured at Kakoya and Koema Caves were not available for similar analysis.

 

Map of Sierra Leone showing Bat trapping locations. Enlarged map shows locations of caves where populations of Marburg Virus-positive Egyptian Rosette Bats, Rousettus aegyptiacus, were discovered (orange circles). The numbers of Egyptian Rousette Bats captured at each site are shown below the cave name. Shown on the map of Africa are locations of Marburg Virus discovery in Egyptian Rousette Bats without an outbreak (blue circles), known Marburg Virus outbreaks (yellow circles), and the fragmented geographic range of the Marburg Virus natural reservoir, Rousettus aegyptiacus (orange shaded). Amman et al. (2020).

Marburg Virus sequences from small diagnostic NP and VP35 gene fragments were determined from 10 of the 11 polymerase chain reaction-positive bats using an array of sequencing approaches, depending on the institution performing the surveillance and sequence analysis. These Marburg Virus sequences were then compared by maximum-likelihood phylogenetic analysis to 128 NP and/or VP35 sequence fragments obtained previously from Egyptian Rousette Bats or Humans in Uganda, Democratic Republic of the Congo, Angola, Gabon, and Kenya. The phylogenetic analysis shows that the Sierra Leone-derived Marburg Virus sequences are most closely related to sequences obtained in Gabon and Angola. In addition, Marburg Virus full-length genome sequences were determined by genome walking of Marburg Virus RNA extracted from oral swabs and whole blood (2), one of which was phylogenetically similar to the Angola-like Marburg Virus isolates (4). Unexpectedly, Marburg Virus isolate sequences from Bats nos. 960 (2), 968, and 1000 were 100% identical across the full-length Virus genome. To rule out cross-contamination during Virus isolation, RNA was extracted directly from Egyptian Rousette Bats tissues and approximately 5 kb of Marburg Virus RNA was sequenced using an Angola strain-specific tiling and amplification approach. As with the Marburg Virus isolate sequences, all tissue-derived Marburg Virus sequences from those three Bats were 100% identical.

Among the 193 Egyptian Rousette Bats captured at Kasewe Cave and Tailu Village, 140 (72.5%) were juveniles (forearm length under 90 mm), and 53 (27.5%) were adults. All of the Marburg Virus polymerase chain reaction-positive Kasewe Cave Egyptian Rousette Bats (9/186) were classified as juveniles (4.8%). A total of 242 Egyptian Rousette Bats were sampled at Kakoya and Koema Caves. Of these, 87 (36%) were juveniles and 155 (64%) were adults. Like the Kasewe Cave and Tailu Village sites, all Marburg Virus polymerase chain reaction positive Egyptian Rousette Bats (2/242; 0.8%) were juveniles. A significant age bias was detected among Marburg Virus-positive Bats; all 11 polymerase chain reaction-positive Bats were juveniles. No sexual bias with respect to Marburg Virus active infection was detected between male (6) and female (5) polymerase chain reaction-positive Bats.

Marburg Virus-specific IgG antibody was detected in 24/140 (17.1%) Egyptian Rousette Bats captured at Kasewe Cave (136 serum tested) and Tailu Village (4 serum tested). Notably, two of these Marburg Virus IgG antibody-positive Bats were also positive by real-time quantitative reverse transcription polymerase chain reaction. No sexual bias was observed in Marburg Virus-specific IgG antibody-positive Egyptian Rousette Bats (5/49, or10.2%, female; 19/91, or 20.9%, male). Consistent with previous studies of wild-caught Egyptian Rousette Bats in Uganda, there was a significant age bias, as 32.4% of adults (12/37) were antibody-reactive to Marburg Virus compared to 11.7% of juveniles (12/103). Sera from Egyptian Rousette Bats captured at Kakoya and Koema Caves were not available for IgG analysis.

Amman et al. present evidence of active Marburg Virus circulation in West African Egyptian Rousette Bat based on polymerase chain reaction, antibody, and Virus isolation data and provide the first report of an Angola-like strain of Marburg Virus since it was first detected in humans in 2005. Importantly, this discovery occurred prior to any known Marburg Virus disease outbreak in Sierra Leone and was used to implement evidence-based public health messaging to at-risk communities about Marburg Virus spillover risk. To accomplish this, a comprehensive One Health communications approach leveraging the human, animal, and environmental and emergency health sectors within the Ministries of Health and Sanitation, and Agriculture and Forestry and Food Security along with other international partners was implemented across national, district, and local community levels. Through several engagement meetings with Ministry of Health and Sanitation and with several relevant ministries, departments and agencies, (Ministry of Agriculture Forestry and Food security, Ministry of Local Government, Ministry of Lands, Ministry of Mines and Mineral Resources, Environment and Protection Agency, Office of National Security) over a two-week period, briefing documents including Marburg factsheets, Marburg Virus disease preparedness, detection and response plans were developed and presented at a national conference. This resulted in recommendations for public health outreach, with a team comprised of key stakeholders (government health and agriculture units, universities, development partners and district and local authorities) across the capital city and three of the districts (Moyamba, Koinadugu and Kono). This outreach team conducted initial information sharing events in each community near the Egyptian Rousette Bat colonies followed by regular in-person meetings with traditional community leaders and other local stakeholders to provide key messages related to virus exposure risks and methods to reduce contact with Bats. Concerns raised by local communities where bushmeat consumption brings them in contact with Bats for livelihood were noted and discussed, and local perceptions about Bats were explored in developing options for minimizing exposure risks. As an additional national-level public preparedness measure, Marburg Virus disease has now been included in testing regimens at national laboratories in Sierra Leone.

Marburgviruses have been found in multiple Egyptian Rousette Bat populations across sub-Saharan and South Africa. Though fragmented, the geographic range for Egyptian Rousette Bats extends into West Africa, covering areas of Liberia, Sierra Leone, and Guinea that contain fruiting trees and caves. Therefore, finding 11 Marburg Virus positive Egyptian Rousette Bats from three separate districts (Moyamba, Koinadugu, and Kono) in Sierra Leone is not unexpected, and together with previous field studies supports the evidence that Egyptian Rousette Bats are the primary Marburg Virus natural reservoir. The finding of multiple and diverse Marburg Virus genetic lineages simultaneously circulating in geographically distinct locations in Sierra Leone suggests that Marburg Virus has been present in West Africa for an extended period of time and is not a recent introduction from other areas of Africa. Indirect fluorescent antibody data suggested that Human Marburg Virus infections may have occurred and gone unrecognised in Liberia in the late 1970s, yet due to specificity issues with the indirect immunofluorescence antibody test at that time, the significance of the findings were unclear. Nevertheless, the isolation of genetically identical viruses from 3/9 Bats caught at the same cave (Kasewe Cave) was surprising. Of note, all three infected juvenile Bats were caught at approximately the same time (within a day of each other). During similar Marburg Virus surveillance activities in Uganda from 2007–2012, 21 genetically distinct Marburgviruses, including Ravn Virus, were isolated directly from Egyptian Rousette Bats, but none were genetically identical to another. In Sierra Leone, we suspect that finding two or more Bats simultaneously infected with the same Marburg Virus lineage is a consequence of being infected from a single point source, perhaps a supershedder Egyptian Rousette Bat interacting with other Bats in a small colony. Moreover, juvenile Bats are known to roost together in caves, a behavior that may facilitate Bat-to-Bat transmission from infected to susceptible individuals. In addition, the field teams did not observe evidence of massive Egyptian Rousette Bat colonies at Kasewe, Kakoya, and Koema Caves like those seen in East Africa making multiple infections stemming from one source more likely. The determination that the Egyptian Rousette Bat colonies are comparatively small is based on the lack of widespread fecal deposits on vegetation near the colony entrances, unlike the copious amounts normally seen in East African Egyptian Rousette Bat populations. Future investigations will include mark-recapture studies to better estimate population sizes at these locations. Overall, the presence of the Egyptian Rousette Bat natural reservoir throughout portions of sub-Saharan Africa implies that Marburgviruses could be present in Bat populations in many localities with suitable habitat for this species even though no Marburg Virus disease outbreaks have yet been recorded.

The Marburg Virus infection data from the four capture sites indicates an age bias towards juvenile Egyptian Rousette Bats that is consistent with previous studies in Uganda and South Africa. Overall, more juveniles were actively infected with Marburg Virus, while more adults had antibody reactive to Marburg Virus. As with Uganda and South Africa, this is indicative of juveniles having maternal antibody for the first few months after birth, providing protection against Marburg Virus infection. That antibody eventually wanes, leaving the older (4-6 months) juvenile cohort susceptible to infection. As the Bats get older, the chances of having been infected with Marburg Virus increase, leading to the increased prevalence of Marburg Virus-specific antibody detected in the adults.

The Marburg Virus phylogeny shows that sequences obtained from Egyptian Rousette Bats in Sierra Leone align most closely with viruses previously found in Egyptian Rousette Bats in Gabon and Democratic Republic of the Congo from 2006–2009, and in Humans in Angola in 2005. The detection of an Angola-like strain is noteworthy because this is the first time it has been identified in Egyptian Rousette Bats even though all other major Marburgvirus lineages, including Ravn Virus, have been detected co-circulating in a single Egyptian Rousette Bat population in Uganda or Democratic Republic of the Congo. In that context, the overall genetic diversity detected to date in the West African Marburg Virus sequences is comparatively lower and may be a consequence of smaller colony sizes compounded by long-term immunity in previously infected bats. Experimental infection studies of captive Egyptian Rousette Bats have shown that bats retain immunity to Marburg Virus reinfection for up to two years despite diminished antibody levels, suggesting that reinfection is not a major driver of Virus persistence in the population. This type of infection dynamic in Egyptian Rousette Bats would further limit the number of susceptible Bat hosts within a colony, thereby potentially limiting the number of Virus strains that can co-circulate within an Egyptian Rousette Bat roost. The fact that the Marburg Virus strains detected in Sierra Leonean Egyptian Rousette Bats are most similar to those seen in other locations on the west coast of Africa (Gabon and Angola) may be reflective of restricted Egyptian Rousette Bat movement and consistent with isolation of Egyptian Rousette Bat populations in Sierra Leone from the larger metapopulation of Egyptian Rousette Bats across most of Central and East Africa. One reason for this isolation could be loss of contiguous habitat through degradation of forested lands that bridge the gap between the Congo Basin and West Africa.

The clear and unwavering recommendation by the Amman et al. is for individuals living and working in close proximity to caves and mines inhabited by Egyptian Rousette Bats to avoid these Bats. Extermination of a reservoir species as a means of zoonotic pathogen control has been shown to be ineffective and can result in higher ratios of active infection. In one recent example, a Ugandan gold mine was sealed and more than 100 000 Egyptian Rousette Bats destroyed. Over the course of several years, the Bats returned and the prevalence of Marburg Virus infection in the Bat population more than doubled. This recolonization was soon followed by the largest human Marburg Virus disease outbreak in Ugandan history, centered in a nearby town. These data show that culling Bat populations may lead to increased Human health risks and thus should be avoided as a pathogen control measure. Furthermore, as a frugivorous species, Egyptian Rousette Bats play an extremely important ecological role in forest regeneration by dispersing seeds and facilitating pollination of the fruiting trees they visit on a nightly basis. The ecological benefits of Bat activity are critical for the survival of the threatened environment in which they live. Tropical forests in Sierra Leone, Liberia, and Côte d’Ivoire were reported to be most at risk in terms of vulnerability, exposure, and pressure from agricultural expansion. Of those West African countries, Sierra Leone was identified as having the greatest pressure from population and income growth resulting in commodity crop expansion and foreign land investment. With reports of existing vegetative cover in the upper Guinean forests showing losses of nearly 80%, ecologically important species like Egyptian Rousette Bats are crucial to the health and longevity of this fragile ecosystem. Perhaps identifying Egyptian Rousette Bats as the source of Marburg Virus in West Africa can serve as a public deterrent and promote Bat avoidance instead of destruction.

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Lassa Fever kills fifty seven in Nigeria.

Fifty seven people have died in an outbreak of Lassa Fever (a form of hemorrhagic fever, similar too, but not as severe as, Ebola) in southern Nigeria between 1 December 2017 and 11 February 2017, according to the Nigerian Centre For Disease Control. A total of 615 suspected cases have been reported, with 193 of these confirmed by laboratory tests. Four of the known deaths are of health workers, with another seven such professionals having fallen in and been confirmed to have the disease. The World Health Organisation has also recorded cases of the disease in Benin and Sierra Leone this year, and several other West African nations are making preparations for outbreaks of the disease, which is endemic to the region.

An isolation ward for Lassa Fever victims in Ondo, Nigeria. Graphic Online.

Lassa fever is caused by the Lassa Virus, a member of the Arenavirida Virus family, single stranded RNA Viruses which cause a range of illnesses in animals and Humans, including Lujo Fever (a hemorrhagic disease endemic to southern Africa), Lymphocytic Choriomeningitis (a form of Meningitis) and Whitewater Arroyo Fever (a hemorrhagic disease endemic tothe southwestern United States). 

Lassa Fever is less lethal than hemorrhagic diseases such as Ebola or Marburg, with about 80% of those infected developing no, or only very mild, symptoms, and a mortality rate of about 1%. However this lack of lethality enables the disease to spread more freely, as asymptotic people can still spread the disease. The Virus also infects Soft-furred Rats, Mastomys spp., which serve as a natural reservoir for the disease, and which are prone to invading Human homes in search of food, particularly during the West African Dry Season, when other food sources tend to be scarce.

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Hundreds dead after mudslide in Sierra Leone.

Three hundred and twelve people, including about sixty children, have now been confirmed dead and it is thought that many more have yet to be found after a hillside collapse on the south slope of Sugar Loaf Mountain, to the south of Freetown, led to a river of mud washing through the town of Regent, on Monday 14 August 2017. The incident happened early in the morning, while many residents of the city were still sleeping, and has swept away hundreds of homes, many in informal settlements built illegally by migrants from the countryside in areas known to be prone to flooding. Several thousand people are thought to have been made homeless in the incident.

River of mud flowing through the town of Regent, Sierra Leone, following a hillside collapse on 14 August 2017.  AFP.

The incident happened following days of heavy rains associated with the West African rainy season. Landslides are a common problem after severe weather, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

 The approximate location of the 14 August 2017 Regent landslide. Google Maps.

West Africa has a distinct two season climatic cycle, with a cool dry season during the northern winter when prevalent winds blow from the Sahara to the northeast, and a warm rainy season during the northern summer when prevalent winds blow from the Atlantic Ocean to the southwest. These warm winds from the Atlantic are laden with moisture, which can be lost rapidly when the air encounters cooler conditions, such as when it is pushed up to higher altitudes by the mountains of the Futa Jallon in Guinea.

 Rainfall and prevalent winds during the West African dry and rainy seasons. Encyclopedia Britanica.

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Sierra Leone reports a new case of Ebola.

Between December 2013 and December 2015 an outbreak of the Viral disease Ebola, which causes an acute hemorrhagic fever, killed a total of 11 315 people in West Africa, with the vast majority of fatalities in Liberia (4809 deaths), Sierra Leone (3955 deaths) and Guinea (2536 deaths). The outbreak was declared over on 14 January 2016, when Liberia was declared officially free of the Virus by the World Health Organization, the last country to be so cleared. However on 15 January Sierra Leone, a country thought to have been clear of the virus since 7 November 2015, reported the death of a young woman earlier this week was confirmed to have been caused by the disease.

Sierra Leone. Wikipedia.

The woman has not been identified, but is understood to have been a 22-year-old student from Lunsar in Port Loko District, who may have contracted the disease in Kambia District, where she stayed from Christmas until 6 January. The woman fell ill while visiting a family home in Tonkalili, and admitted to hospital after visiting a hospital outpatients department suffering from dizziness, and died on 12 January. 

Ebola was not identified while the woman was alive, as she showed no typical signs of the illness. However the disease was diagnosed from swabs which were taken after death as part of an ongoing screening program and sent for testing at Public Health England in the UK. This means that since the since the illness was not identifies until after the victim was buried, none of the precautions usually taken against the spread of the highly contagious disease were taken.

A hundred and nine people have been identified as having ha potentially hazardous contact with the woman, with 28 considered to be at high risk, Three of these people have yet to be traced.Officials from the World Health Organization have also suggested that the burial of the victim may not have been carried out in a safe fashion.

This resurgent outbreak has been linked to the discovery that the disease can linger in other bodily fluids long after it has been cleared from the blood of recovered victims, providing a potential reservoir of infection that cannot be detected by conventional blood tests.

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Evidence for sexual transmission of the Ebola Virus.                                                                             In December 2013 cases of Ebola, a viral haemorrhagic fever with an extremely high mortality rate, began to emerge in Guinea, West Africa, marking the beginning of the most severe outbreak of the disease...

The source of the December 2013 Guinean Ebola outbreak.

In December 2013 cases of the haemorrhagic Virus...

At least 467 dead in West African Ebola outbreak.                                                        At least 467 people have died in an outbreak of  Ebola Hemorrhagic Fever in West Africa that began in February this year. The disease initially appeared in the remote border area between Guinea, Sierra Leone...

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Cryptic diversity in West African Torrent Frogs.

The West African Torrent Frog, Odontobatrachus natator, is found in fast moving streams and waterways in the forests of Guinea, Sierra Leone Liberia, and western Côte d’Ivoire, part of the Upper Guinean Biodiversity Hotspot. While it has been known to science for over a hundred years, a recent study has shown it to be sufficiently genetically isolated from all other Frogs to merit placing it in its own family, the Odontobatrachidae, this being the first family of Vertebrates discovered which is entirely restricted to West Africa.

In a paper published in the journal BMC Evolutionary Biology on 19 April 2015, Michael Barej and Johannes Penner of the Museum für Naturkunde Berlin at the Leibniz Institute for Evolution and Biodiversity Science, Andreas Schmitz of the Department of Herpetology and Ichthyology at the Natural HistoryMuseum of Geneva and Mark-Oliver Rödel, also of the Museum für Naturkunde Berlin at the Leibniz Institute for Evolution and Biodiversity Science examine the genetic diversity of West African Torrent Frogs in order to determine if they were truly all one widespread species or a cluster of morphologically indistinguishable cryptic species.

A West African Torrent Frog, Odontobatrachus natator. Barej et al. (2014).

Cryptic species are species which resemble one-another closely but which are reproductively isolated. These have been known about for a long time in groups such as calling Frogs and Songbirds, where morphologically identical populations can be separated on the basis of different mating calls, but the true extent of hidden diversity in many groups did not become apparent until genetic tools became available to study wild populations in the 1990s. The discovery of cryptic species can have profound implications for conservation efforts, as what was thought to be a single, widespread species with a large population can suddenly be found to be a cluster of species, each with very limited populations and ranges. Cryptic diversity seems to be particularly common among groups such as small Amphibians and Reptiles, but has been found even in large charismatic animals such as Elephants, Giraffes, Baboons and Hammerhead Sharks.

Barejet al. found that the population of Odontobatrachus natator contains six distinct genetic lineages, and though they do not go so far as to name them as new species from this preliminary study, they do indicate that further studies are likely to result in the group being divided into a number of separate species.

Tree resulting from partitioned Bayes and ML analyses of mitochondrial genes 16S, 12S, cytb and nuclear genes RAG1, SIA and BDNF (outgroups not shown). Barej et al. (2015).

The most widespread of these is found in western Guinea, across Sierra Leone and as far to the east as eastern Guinea and eastern Liberia. This includes the area from which the species was first described (Sierra Leone, unspecified), and will therefore retain the name Odontobatrachus natator however the group is subdivided in future. This population is considered to be of ‘Least Concern’ under the terms of the International Union for the Conservation of Nature’s Red List of ThreatenedSpecies.

The most closely related outgroup to this (and therefore the group least likely to subsequently be described as a separate species) was a population found only on the Freetown Peninsula in Sierra Leone. This population is referred to as Odontobatrachus natator (Freetown Peninsula), and while closely related to the larger population, does appear to be separate on the basis of the genes studies and is separated from the main population by a wide area of unsuitable habitat, which may have allowed reproductive isolation to develop. If this population is recognized as a separate species then it would be recognized as ‘Critically Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species, due to the limited geographical range it inhabits.

Environmental niche modelling map of genetically confirmed records of the Operational Taxonomic Units Odontobatrachus natatorand Odontobatrachus natator (Freetown Peninsula). Barej et al. (2015).

In addition four other distinctive genetic lineages are identified, and provisionally named as ‘Operation Taxonomic Units’ (OTUs) 1 to 4. These can be further groups as (OTU 1 and OUT 4) which are most closely related to one-another and the sister group to (Odontobatrachus natatorand Odontobatrachus natator (Freetown Peninsula)), and (OUT 2 and OUT 3) which are more closely related to one-another, and form an outgroup to all the other populations.

OTU 1 is found in the Simandou Range and the Massif du Ziama in south-eastern Guinea, and environmental niche modelling suggests that it may also occur westwards into parts of Sierra Leone. This population is considered to be ‘Vulnerable’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 1. Barej et al. (2015).

OTU 2 was found in western Guinea, though Environmental Niche Modelling suggested that it may also be found as far east as central Sierra Leone, though Barej et al. deem this unlikely. This population is considered to be ‘Vulnerable’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 2. Barej et al. (2015).

OTU 3 was also found in wesertn Guinea, though Environmental Niche Modelling suggests that it may be found as far east as central Sierra Leone and as far west as parts of Guinea Bissau, though againBarejet al. deem this unlikely.This population is considered to be ‘Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 3. Barej et al. (2015).

OTU 4 was found in the Nimba Mountains of southeaster Guinea and the surrounding area, as well as in northeastern Liberia and the Mont Sangbé National Park in western Côte d’Ivoire. Environmental niche modelling suggested that this population could extend across much of eatern Guinea and northern Liberia, and even into eastern Sierra Leone. This population is considered to be ‘Endangered’ under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Environmental niche modelling map of genetically confirmed records of Operational Taxonomic Unit 4. Barej et al. (2015).

Although this is only a preliminary study, the degree of genetic separation between the populations suggests that they may have diverged during the Plio-Pleistocene. This is consistent with palaeoclimatic models of West Africa, which suggest while the region was not directly affected by glaciation during the Pleistocene, glacial intervals at higher latitudes led to a cooler drier climate in which forests withdrew and grasslands expanded. During such periods forest species would have been restricted to isolated refugia, where populations cut off from one-another geographically could become permanently separated by genetic drift.

See also….

Robber Frogs from the mountains of western Mexico.

Robber Frogs of the genus Eleutherodactylus are found from Texas to Guatemala and Belize and across the islands of the Caribbean. The genus was formerly the most specious of any genus of Vertebrate Animals (i.e. it contained more species than any other Vertebrate...

The enigmatic Pleistocene Amphibians of Okinawa Island.

In the late 1960s and early 1970s a series of anthropological excavations were carried out at Minatogawa Fissure on southern Okinawa Island, producing a number of Late Pleistocene Human...

A new species of Fanged Frog from Sulawesi.

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At least 467 dead in West African Ebola outbreak.

At least 467 people have died in an outbreak of  Ebola Hemorrhagic Fever in West Africa that began in February this year. The disease initially appeared in the remote border area between Guinea, Sierra Leone and Liberia, and has spread widely in all three countries, severely straining their already weak public health infrastructure.

Health workers from Doctors without Borders carrying the body of an Ebola victim at a center for victims in Guekedou, Guinea, on 1 April 2014. Seyllou/AFP/Getty Images.

Ebola Hemorrhagic Fever is caused by RNA Viruses of the genus Ebolavirus. It has a reputation for being the world's deadliest viral disease, at least in part due to the 1995 film Outbreak, though this is probably slightly inaccurate as about 10% of victims survive, making it less deadly than diseases such as Rabies. However it is extremely contagious, with know known cure or vaccine, and has a tendency to rapidly overwhelm local health systems as health workers themselves are infected. 

Ebola begins with a fever similar to that caused by Influenza or Malaria, which tends to come on rapidly two-to-three weeks after infection (during at least part of which time the patient is already infectious). This tends to be followed by extreme respiratory tract infection, headaches, confusion, rashes and tissue necrosis and heavy bleeding. Death is generally caused by multiple organ failure.

The only known treatment for Ebola is intensive rehydration, which can improve the survival prospects of patients greatly, accompanied by anticoagulants and procoagulants to mange the diseases attacks on the circulatory system, analgesia to cope with the pain of the disease and antibiotics and antimycotics to prevent secondary infection. Due to the highly contagious nature of the disease it is recommended that healthcare workers wear full-body protection to maintain a barrier between them and their patients; a daunting prospect in the tropical regions of Africa where the disease is endemic.

Healthcare workers from Doctors Without Borders donning special 'Ebola-suits' before entering an isolation ward at a hospital in Guinea. AFP/Getty Images.

Ebolavirus is thought to have a non-human animal vector, since its rapid onset and high mortality rate appears to preclude a permanent residence within Human hosts. Surveys of wild animals have found Ebola infections in Rodents and Great Apes, however these were affected by the disease in a similar way to Humans, and are therefore unlikely permanent hosts. The most likely vectors are thought to be Fruit Bats or small Primates, which are endemic to the areas where the disease occurs and which are widely eaten; cooking meat probably kills the virus, but there is a distinct danger of infection while preparing carcasses. 

The area where the outbreak first occurred has suffered several decades of political instability and warfare, and many people there have a strong mistrust of both civil authorities and western healthcare. Primary healthcare in the region is often provided by traditional healers, who use principally herbal medicines. Such healers were entirely unprepared for a disease as virulent as Ebola, and many themselves became infected, first passing on then succumbing to the disease. 

The disease spread rapidly as people attempted to look after sick relatives at home, and possibly also by local customs that dictate washing and sitting vigils with the dead. Later intervention by government and NGO healthworkers was treated with extreme suspicion, as this involved taking sick relatives and holding them in isolation for treatment, going against local tradition and extremely alarming in an area with recent memories of arbitrary political detentions and kidnaping of civilians by armed militia groups, and there have been a number of reported incidents of people attacking healthworkers and even rescuing sick relatives from isolation centers. In Liberia in particular there have been persistant rumors that the disease is a hoax created by the government to cover up a series of corruption scandals.

As communities have come to realize the threat of the disease, many people have responded by fleeing, in turn spreading the illness to new areas. This has led to the disease spreading across all three countries, reaching major cities such as Bo, Conakry and Monrovia, where crowded urban dwellings have the potential for the disease to spread even more rapidly. As such neighbouring countries Guinea Bissau, Senegal, Mali and Côte d’Ivoire are in a state of high alert, and there are serious concerns about the disease spreading further via international air or shipping routes. 

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