What we know about the Mar­burg virus

The Con­ver­sa­tion Africa’s health and medicine ed­i­tor Candice Bai­ley spoke to the Na­tional In­sti­tute for Com­mu­ni­ca­ble Dis­eases about the Mar­burg virus

The East African - - NEWS -

What is the Mar­burg virus and why is it con­sid­ered dan­ger­ous?

The Mar­burg virus is prob­a­bly most eas­ily in­tro­duced as the sis­ter of the in­fa­mous Ebola virus. The viruses are sim­i­lar in their ge­netic and struc­tural makeup, they’re trans­mit­ted from hu­man-to-hu­man and their clin­i­cal pre­sen­ta­tion in hu­mans is sim­i­lar. But there are some marked dif­fer­ences. For ex­am­ple, apart from over­lap­ping in two coun­tries, they have been de­tected in dif­fer­ent parts of the African con­ti­nent. Mar­burg virus has been re­ported in spo­radic out­breaks in East­ern and South­ern Africa — in­clud­ing Uganda, Kenya, the Demo­cratic Re­pub­lic of Congo and An­gola. A case of Mar­burg virus dis­ease in South Africa was traced back to po­ten­tial exposure in Zim­babwe. For its part, Ebola has also been re­ported in the DRC and Uganda, as well as Su­dan, Gabon, Guinea, Sierra Leone and Liberia.

There are also dif­fer­ences in the nat­u­ral ecology of the two viruses. Cur­rent ev­i­dence sup­ports the hy­poth­e­sis of cir­cu­la­tion of Mar­burg virus in cave dwelling bats such as Rouset­tus ae­gyp­ti­a­cus (or Egyp­tian fruit bat), while most be­lieve that the Ebola virus is associated with the for­est dwelling bat species.

There have only been 12 known out­breaks of the Mar­burg virus in the 50 years fol­low­ing its dis­cov­ery. It was first de­scribed fol­low­ing an out­break of haem­or­rhagic fever in lab­o­ra­tory tech­ni­cians that were han­dling mon­keys ex­ported from Uganda to Mar­burg, Ger­many in 1967. A to­tal of 31 cases were re­ported in Ger­many which re­sulted in seven deaths.

Eight years later, the virus reared its head again — this time in South­ern Africa. The case in­volved an Aus­tralian back­packer who trav­elled through Zim­babwe and was di­ag­nosed with the Mar­burg in South Africa. The back­packer’s travel com­pan­ion and a South African nurse were also af­fected.

In the fol­low­ing years, out­breaks of Mar­burg fever of­ten in­volved a hand­ful of cases, with a num­ber of out­breaks only re­port­ing a sin­gle case. This changed in 1998, when more than a 150 cases of Mar­burg fever were re­ported in the DRC. The big­gest and most lethal out­break of Mar­burg fever hap­pened in Uige in An­gola in 2004-2005. More than 250 cases re­ported with a fa­tal­ity rate of 90 per cent. In 2008, two cases of Mar­burg fever were re­ported in tourists who vis­ited Python Cave in Uganda prior to fall­ing ill in the US and the Nether­lands.

How does one con­tract it and how can it be treated?

How the virus is trans­mit­ted to hu­mans hasn’t been pinned down. What is known is that cases from sev­eral out­breaks have been associated with caves or con­tact with cer­tain bat species. But which type of con­tact constitutes exposure to the virus must still be con­clu­sively de­ter­mined.

Once the virus en­ters the hu­man pop­u­la­tion, the virus spreads in ways that are sim­i­lar to the Ebola virus. This in­cludes di­rect con­tact with the ex­cre­tions and se­cre­tions of a per­son af­fected by the virus. This means that fam­ily con­tacts and care tak­ers, and im­por­tantly health care work­ers, are at most risk for con­tract­ing the dis­ease.

Should the world be wor­ried about the pos­si­ble rapid spread of the virus?

Any out­break of vi­ral haem­or­rhagic fever should be taken se­ri­ously. If the ap­pro­pri­ate mea­sures are not ap­plied to con­tain the out­break in good time, there’s al­ways the risk that a larger out­break may evolve. This was a les­son learnt from the West Africa Ebola out­break.

Is there a con­cern about the fact that this is the sec­ond out­break in three years?

Most of the out­breaks — al­though they haven’t been the big­gest — have been re­ported from Uganda over the years. The dis­cov­ery of Mar­burg virus in 1967 was traced back to Uganda, and a to­tal of three ad­di­tional out­breaks (not count­ing the cur­rent) have been re­ported from the coun­try. Also, two tourist associated cases men­tioned were also linked to exposure in Uganda. It isn’t pos­si­ble to say at this point in time what lies be­hind this pat­tern. It may only re­late to the abil­ity to de­tect the out­breaks more swiftly.

Di­ag­no­sis of the first re­ported case was rapid ... iso­la­tion ca­pac­ity was es­tab­lished re­ally quickly.”

What chal­lenges does a coun­try like Uganda have in deal­ing with the Mar­burg virus?

Uganda has a track record of deal­ing with Mar­burg and Ebola out­breaks. There are a num­ber of en­cour­ag­ing signs in the way that the coun­try is re­spond­ing to this out­break. These in­clude the fact that di­ag­no­sis of the first re­ported case was rapid, that there is a swift re­sponse to trace con­tacts, that iso­la­tion ca­pac­ity was es­tab­lished re­ally quickly and that in­ter­na­tional sup­port was sought to help con­tain the out­break.

The af­fected area is in the Kween district of Uganda, about 300 kilo­me­tres north­east of Kam­pala. The area is re­mote and moun­tain­ous. This may mean that the out­break will not spread eas­ily. But it does mean that there are chal­lenges in the lo­gis­tics of out­break sup­port ef­forts.

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