The world is currently witnessing two simultaneous outbreaks of the Marburg virus - one in Equatorial Guinea and the other in Tanzania. The Marburg virus is as lethal as Ebola, to which it is closely related, but it has been rare until now.
On March 21, Tanzania announced an outbreak of the Marburg virus, putting the world in uncharted territory. As of April 6, there have been eight confirmed cases of the virus, resulting in five deaths, according to the US Center for Disease Control (CDC). Despite the low risk of the disease reaching the US, the CDC has issued a health alert warning doctors to be aware of the potential for imported cases.
Currently, the situation in Equatorial Guinea seems to be the most severe. The World Health Organization (WHO) issued an alert on February 25 after several suspected deaths from Marburg were discovered in two villages in the north of the country in early January. Since then, there have been 15 confirmed cases of Marburg in Equatorial Guinea, with eleven of those patients dying just days after showing symptoms such as vomiting, diarrhea, nausea, and high fever.
However, the WHO is concerned that the official tallies underestimate the disease's actual toll. Cases in Equatorial Guinea come from regions that are quite far from each other, suggesting that there may be undetected community spread of the virus in the country. According to Paul Hunter, an epidemiologist at the University of East Anglia, "This is a problem - this unprecedented outbreak of the Marburg virus in two different countries."
Cesar Munoz-Fontela, a specialist in tropical infectious diseases at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, added, "There has been an acceleration in the number of Marburg virus outbreaks over recent years."
How bats evolved into humans
Marburg virus was initially detected in humans in 1967 in the German city of Marburg. Since the late 1970s, the virus has broken out more than a dozen times in Africa, yet there has never been more than one outbreak every three or four years until recent years.
The Egyptian fruit bat acts as the virus's natural host and transmits it to humans either directly or via an intermediate host such as monkeys.
Fortunately, most of these outbreaks have been small, affecting no more than a dozen people each time, according to official statistics. However, Marburg, like Ebola, is one of the deadliest viruses and belongs to the filovirus family of diseases, with mortality rates as high as 90 percent.
This grim statistic was seen in the two largest Marburg outbreaks. Between 1998 and 2000, DR Congo recorded 154 confirmed cases, with 128 fatalities. Four years later, Angola recorded 252 infected patients, of which 227 died.
Specialists since then have concluded that rapid medical intervention can reduce the fatality rate. Despite this, the fatality rate remains close to 50 percent even with timely care, according to the WHO.
Not vaccinated
Marburg is considerably more dangerous than Ebola, as it lacks a vaccine or post-exposure treatment, according to Munoz-Fontela. The absence of a vaccine is due to the lack of interest in developing one until the West African Ebola epidemic in 2014, which led to the creation of the Everbo jab in 2015. The 2014-2016 Ebola epidemic in West Africa resulted in the loss of over 11,000 lives.
In response to the increasing incidence of epidemics in recent years, the WHO has developed a policy of swift vaccine development and is now prepared to test vaccine candidates in Equatorial Guinea and Tanzania, as announced at the end of March.
Since 2020, there has been at least one new outbreak each year, which may be due to the improved detection of infectious diseases in Africa, according to Hunter. National health authorities in Africa are now more aware of the risk of virus spread, actively searching for potential outbreaks more efficiently. However, Munoz-Fontela cautioned that this is not necessarily reassuring, as it suggests that Marburg outbreaks may have been missed in the past and the virus is not as rare as previously thought.
Hunter noted that environmental factors, such as global warming and other human activities, have made conditions more favorable for the spread of the virus. The encroachment of humans into animals' natural habitats increases the risk of exposure to new infectious diseases, as people are more readily exposed to them. In the past, a person could get infected by a bat in a forest cave and die far away from others, but now humans are moving closer to animals' natural habitats, and viruses spread more easily.
Not as easily spread as COVID-19
Scientists have suggested that increased human exposure to animal habitats may have caused the emergence of COVID-19, according to recent findings.
However, it's important to note the differences between the Marburg virus and COVID-19. Fortunately, the outbreak of a global Marburg pandemic is less likely than it was in the case of COVID-19.
Firstly, Marburg only becomes contagious when symptoms start to appear, which is between two and 21 days after contracting the virus. Therefore, there is no risk of transmission by asymptomatic carriers going unnoticed.
Secondly, the Marburg virus is less easily transmissible than COVID-19, as it requires contact with the bodily fluids of an infected person. Unlike COVID-19, which spreads through respiratory droplets when an infected person coughs or sneezes.
Furthermore, only a small amount of the Marburg pathogen can infect another person, usually during the haemorrhagic phase of Marburg. This poses a risk to healthcare workers and family members around the patient's bedside.
Filoviruses, such as the Marburg virus, appear to be more stable than coronaviruses such as COVID-19, which means the virus is not likely to mutate. As a result, a vaccine would not require regular updates to remain effective.
However, vaccine development against the Marburg virus is still in its earliest stages. The WHO has estimated that both ongoing outbreaks pose a "moderate" risk at the regional level. The Kagera region in Tanzania has busy borders with Uganda, Rwanda, and Burundi, whereas Equatorial Guinea has porous borders with Cameroon and Gabon.
Hunter concluded that the next few weeks would prove illuminating about how much the disease has spread, as no new cases have been reported. It will take as long as three weeks to find out if contacts of the previous recorded cases have been infected.
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