Marburg is a highly infectious virus from the family Filoviridae (which includes Ebola virus), and is associated with a high fatality rate (~90%) and severe haemorrhagic symptoms. Originally described in simultaneous outbreaks in Germany and Serbia in 1967, it is now confined to sub-Saharan Africa, including Uganda, Zimbabwe, Kenya and Angola. Infections are sporadically reported, and are often identified in mine workers or tourist’s who have reported visiting caves. In 2007, a natural animal reservoir of Marburg virus was identified in the Egyptian fruit bat, Rousettus aegyptiacus. Due to the curiously spotty nature of infections, researcher’s from nine different disease control centres collaborated to find out what ecological factors might influence virus spillover from bats into the human population. They focussed their analysis on one location: Python Cave in Queen Elizabeth National Park, Uganda. 40 out of the 1622 bats they captured (2.5%) were infected with Marburg virus: since the cave has an estimated total population of 40,000, this corresponds to 1000 actively infected bats at any one time, meaning a low level of infectious virus is constantly in circulation. Young bats (6 months of age) were especially susceptible to infection during two periods of the year, and these times roughly corresponded with historical episodes of Marburg virus outbreaks. Thus, seasonal fluctuations of infection are associated with young bat populations, and probably represent periods of increased public health risk.
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Amman BR, Carroll SA, Reed ZD, Sealy TK, Balinandi S, Swanepoel R, Kemp A, Erickson BR, Comer JA, Campbell S, Cannon DL, Khristova ML, Atimnedi P, Paddock CD, Kent Crockett RJ, Flietstra TD, Warfield KL, Unfer R, Katongole-Mbidde E, Downing R, Tappero JW, Zaki SR, Rollin PE, Ksiazek TG, Nichol ST, & Towner JS (2012). Seasonal Pulses of Marburg Virus Circulation in Juvenile Rousettus aegyptiacus Bats Coincide with Periods of Increased Risk of Human Infection. PLoS pathogens, 8 (10) PMID: 23055920