First there was Ebola, then there was Marburg

The family of Filoviruses includes not only 5 types Ebola, but two species of a very closely related virus known as the Marburg virus. While the Ebola epidemic rages in Western Africa, the closely related Marburg virus has emerged in Uganda at an inopportune time.

The Ugandan Ministry of Health reported yesterday that a male health care worker died of Marburg virus on September 30th. Following his death, his brother has come down with symptoms consistent with Marburg infection.

Given the heightened state of alert due to the Ebola outbreak, this emergence of Marburg virus may be contained more rapidly than it would have otherwise, yet cause for concern still exists.

The Marburg virus was identified in the 1960s when workers in Marburg, Germany were exposed to the meat of infected green monkeys. Mortality rates from the eleven outbreaks recorded to date have varied, but the largest outbreak in Angola recorded a fatality rate of 90% for the 252 cases.

Previously covered here, the pathology of the Filovirus family makes treatment incredibly difficult for patients infected with Ebola or Marburg virus. Furthermore, long incubation periods allow the infected to spread the virus without visibly displaying symptoms.

These two elements combined with the extent of possible exposure during this case will make containment difficult. It was estimated that this health worker came into contact with 60 other health care workers during the incubation period as well as 20 other people from the area.

While this outbreak occurred in a well-informed population with understanding of proper containment measures, the infection of fellow health care workers creates a situation where a population of vulnerable hospital patients may also have come into contact with the virus. Furthermore, patient zero traveled while exhibiting symptoms, which is also the time that viral load is the highest.

It remains to be seen how well containment measures will limit the spread of this infection.

Marburg virus has been generally perceived to be less lethal than Ebola, possibly due to fewer outbreaks and fatalities. For this reason, research on treatment or prevention has lagged behind that of Ebola, with only a few companies such as Tekmira and Sarepta working on RNA anti-sense technologies, which often only work for immediate post-exposure prevention.

Other than these companies, the only major research was an attempt by the Soviet Union to weaponize the Marburg virus, where two laboratory accidents led to two infections and one death.

Regardless of the outcome of this outbreak, the close proximity and possible devastation caused by two concurrent filovirus infections calls into question the interaction between humans and their environment in regions with natural hemorrhagic fever reservoirs. The Lake Victoria region is known to hold several natural reservoirs of Marburg and Ebola – these are assumed to be maintained in fruit bats or possibly primates.

This close proximity will require that the general populace be educated on the dangers of bushmeat and preliminary signs of viral hemorrhagic fever, otherwise future outbreaks that endanger the global population are likely to be observed again.

Image: CryoElectron Microscopy image of the Marburg virus nucleocapsid. (Image credit)

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