ZANZIBAR'S VIRAL UNDERGROUND

by Martin Walsh

The walkway between caves at Mchekeni, Zanzibar (photo: Martin Walsh)

I worry about caves. I’ve been worrying about them ever since reading about the role played by Kitum Cave in the known history of Marburg virus disease. In the 1980s, two separate visitors to this “elephant cave” in Mount Elgon National Park were infected and subsequently died. Egyptian fruit bats (Rousettus aegyptiacus) have since been identified as a reservoir host for marburgviruses, and it may well be that the inhalation of microbes from bat guano was the means by which these unfortunate tourists contracted the deadly disease.

I’m also fascinated by caves: they’re contagious in more ways than one. The islands of the Zanzibar archipelago, with their extensive limestone reef terraces, are riddled with caves and sinkholes. They’re a distinctive feature of the coral rag or karst landscape of both Unguja and Pemba, though often hidden from sight by thick vegetation, especially along the forested scarps in the south and east of the main island. Many of the caves have cultural significance as mizimu, the abodes of spirits that are regularly propitiated by the local guardians who have inherited this responsibility.

Entering one of the caves at Ufufuma (photo: Martin Walsh)

I wasn’t really aware of either the abundance of caves or the extent of this practice until Helle Goldman and I began researching knowledge and beliefs about the Zanzibar leopard (Panthera pardus adersi) in 1996. There’s a strong association between leopards and caves, because of the spiritual significance of both and the fact that leopards were believed to be often found in and around them. In some cases, leopards themselves are the spirits that subterranean offerings are made to. 

More recently, Maximilian Chami and others have begun documenting these and other sacred sites, though we’re far from possessing anything like an inventory or gazetteer. Following his father Felix Chami’s pioneering excavations, caves have also been providing us with remarkable insights into Zanzibar’s past, including the people and fauna of Unguja before it became an island. I’ve been a minor contributor to discussions about some of the emerging zooarchaeological evidence – and I look forward to more.

Unsurprisingly, some of the limestone caves on the eastern side of Unguja are now tourist venues. The impressive Mchekeni Caves, in the Kiwengwa-Pongwe Forest Reserve, have been open since 2006, though visitor numbers can be very low. Other caves have been developed privately. Kuza Cave in north Jambiani is more like a rock shelter or overhang (presumably exposed by an earlier collapse), with a beautiful turquoise pool that tourists are encouraged to swim in. The caves at Ufufuma, roughly halfway between Mchekeni and Kuza, are used by a traditional healer (mganga), who also entertains fee-paying tourists.   

Bats in the south cave at Mchekeni (photo: Martin Walsh)

Whenever I’ve visited Mchekeni, I’ve felt distinctly uneasy penetrating deep into the southern cave. This is not because there’s no path and it’s unlit, it’s because I’m thinking about bats. There are plenty of small bats clinging to the walls, harmless enough. But I can’t help but wonder about the viruses they might be carrying. Spillover events may be rare, but as the ongoing global pandemic has painfully reminded us, they can happen, and bats are, for better or worse, the reservoir hosts of numerous viruses, SARS-CoV-2 included.

Perhaps I should be more worried about the fruit bats hanging in the trees, and the fruit that they may have slobbered or defecated on. Or fretting about Pemba, where flying foxes (Pteropus voeltzkowi) and other bats have traditionally been hunted as bushmeat. Who knows what harms this may have caused in the longue durée of island history? Of course, Zanzibar has more pressing public health problems to deal with in the present. Sooner or later, though, Zanzibar and Tanzania will have to start thinking about the biosecurity of the growing number of caves on the tourist trail. Next time I go down there, I’m wearing a mask.

Further reading

Bardenwerper, Julie 2009. Spirits and Sacred Sites: A Study of Beliefs on Unguja Island. SIT Study Abroad, Independent Study Project (ISP) Collection. Paper 759.

Chami, Maximilian F. 2019. “Sacred Limestone Caves”: Management and the Use of Sacred Heritage Places in Limestone Cave Areas along the Swahili Coast of Indian Ocean in Tanzania. Unpublished PhD dissertation, Brandenburg University of Technology Cottbus–Senftenberg.

Chami, Maximilian F. & Felix A. Chami 2020. Management of sacred heritage places in Tanzania: a case of Kuumbi limestone cave, Zanzibar island. Journal of Heritage Management 5 (1): 71-88.

From the Kuza Cave website, www.kuzacave.com

Faulkner, Patrick et al. 2019. Long-term trends in terrestrial and marine invertebrate exploitation on the eastern African coast: insights from Kuumbi Cave, Zanzibar. The Journal of Island and Coastal Archaeology 14: 479–514.

Goldman, Helle & Martin Walsh 2019. Classifying, domesticating and extirpating the Zanzibar leopard, a transgressive felid. Norsk Antropologisk Tidsskrift 30 (3-4): 205-219.

Prendergast, Mary E. et al. 2016. Continental island formation and the archaeology of defaunation on Zanzibar, eastern Africa. PLoS One 11 (2): e0149565.

Quammen, David 2012. Spillover: Animal Infections and the Next Human Pandemic. London: Vintage Books.

Walsh, Martin 1995. Eating bats on Pemba island: a local innovation or cultural borrowing? Mvita: Newsletter of the Regional Centre for the Study of Archaeology in Eastern and Southern Africa 6: 15-18.

Walsh, Martin 2011. From green monkey disease to fruit bat viruses. East African Notes and Records, 26 December 2011.

Walsh, Martin & Helle Goldman 2007. Killing the king: the demonization and extermination of the Zanzibar leopard. In E. Dounias, E. Motte-Florac & M. Dunham (eds.) Le symbolisme des animaux: L'animal, clef de voûte de la relation entre l'homme et la nature? Paris: Éditions de l’IRD. 1133-1182.