Prentice Collection: The Survey & Control of River Blindness (Onchocerciasis) in Uganda 1959

This film is held by the British Empire & Commonwealth Museum (ID: 2004/051/001).


European team tackle eradication of the fly which causes Onchoceriasis ('River Blindness'). Habitat of the fly and larvae. Exploration of the Victoria Nile for infestation sites. Construction of cross-river pipeline to carry insecticidal solution. Worker's camp and arrival of supplies. Solution (DDT and fuel oil) added to river. Checking efficiency of treatment. Aircraft dropping beer cans and milk cartons containing DDT solution into inaccessible streams.

Production / Donor Details: Mr Prentice was Senior Entomologist, Vector Control Division, Ministry of Health, Uganda, from 1951 to 1973.



The single film that composes the Prentice Collection, Similium Damnosum – Vector of Onchoceriasis, details a 1959 attempt by the Ugandan Ministry of Health to control the spread of the disease onchocerciasis. Also known as ‘river blindness’, onchocerciasis is caused by the presence in the body of a nematode worm, Onchocerca volvulus, the females of which release thousands of tiny offspring per day into the host body. Though the adult worms live within the skin, the microscopic worm larvae (‘microfilariae’) travel through the body and eventually die, at which time they cause itching, depigmentation, lymphatic problems, and blindness ( Attempts to control the disease focussed on the aquatic larval stage of the eponymous Similium damnosum fly (commonly known as the ‘Mbwa [dog] fly’, on account of its painful bites), a blood-eating fly that is the major vector of the disease. In Uganda, the fly was found to breed in ‘astronomical numbers in the many rapids which characterise the course of the Nile between Lake Victoria and Lake Kyoga’ and the affected areas suffered onchocerciasis infection rates of close to 100% (Prentice: shot list in BECM accession notes).

The particular control programme shown in the film was initiated during 1959, in order to protect the workers that would be constructing a planned hydro-electric power station at Karuma Falls, on the Victoria Nile. Control of the fly would protect labourers from both the irritation of the fly-bites (tests in the area suggested a bite-rate of 300 bites per hour) and the danger of onchocerciasis infection. Mr. Prentice, then the Senior Entomologist (Vector Control) in the Ugandan Ministry of Health, was in charge of the project. It was found that the 85km stretch of the Nile near the projected power-station – the ‘Kabalega’ Nile below the Murchison Falls, ‘simply a canal characterised by rapids interspersed with long quiet pools’ – was also the sole breeding point for the fly in the area, making effective control a real possibility (Prentice: papers in accession notes).

Figures given by Mr. Prentice in a paper on river blindness that was submitted to the BECM with the film (‘Onchoceriasis Control Programme in Uganda’: undated, henceforth OCPU) suggest that applications of DDT earlier in the 1950s had significantly reduced fly numbers in some areas, and a note in the May 1974 issue of the British Medical Journal credits Prentice’s colleague, G. R. Barnley, with having largely controlled the disease on the Ugandan Nile (Prentice, OCPU, 8; BMJ,1974, 401-2). The method of control was release DDT dissolved in fuel oil into the rivers above areas where the filter-feeding fly larvae were concentrated. Earlier trials had established that relatively low concentrations – between 0.2 to 0.5 parts per million – were enough to eradicate Similium larvae, apparently without causing serious ecological damage to the river, though he does note that after the treatments shown in the film algal blooms covered rocks and vegetation (Prentice, op.cit., 6); Holden (1984), in her account of Barnley’s earlier attempt at Similium control, reports that there was ‘no time for ecological investigation’ (Holden, 1984, 163). According to the figures supplied by Mr. Prentice, over 10,000kg of DDT, mixed with fuel oil, was released into the Victoria Nile between 1952 and 1961; despite this, and despite Barnley’s earlier success, he in fact indicates that the control programme shown in the film was rather unsuccessful, and was in any case abandoned when the Government chose not to press ahead with the dam and power plant (ibid., 5-6, 8).

It seems from Mr. Prentice’s notes that the film was intended for lay (probably African) audiences, in order to disseminate information about Government measures to control the fly; a letter in the accession notes mentions ‘unsophisticated audiences’, and the film was screened at 16fps in order to allow time for explanatory commentary. It is also possible that the films were used for training purposes. An earlier film on the same subject was also made by Mr Prentice; shot in 1957, in a different area, it was titled ‘Onchoceriasis and the Control of the Mbwa Fly’, and detailed an earlier fly control scheme, this time centred on protecting the staff of a ‘projected Coffee Research Station’ near Mount Elgon. It is noteworthy that both the control projects he was part of did not have the welfare of local people as a primary concern, and rather were focussed on protecting the staff and workers on projects relating to the colonial presence. A shot list is held at the BECM, though there is no copy of the film; it apparently featured scenes of the Entomology team explaining the disease and its vectors to local people and representatives of the Local African Government, and various sequences of the control programme itself.



Well-constructed for its purpose and filmed with effective if workman-like cinematography, Similium Damnosum… is a chronological record of the Karuma Falls fly control project from its beginnings, through the construction of the river dosing system, to the testing of an improvised aerial DDT dosing programme (involving the dropping of empty beer cans and milk cartons filled with DDT solution into inaccessible river tributaries).

A detailed shot list, written by Mr. Prentice, is held by the BECM, and this gives a full description of all the events shown in the film, as well as identifying the Deputy Director of Medical Services (a Dr. Davies) who visits the test site and is taken out on a small motorboat by Mr. Prentice (the sequence begins at 16.07: ‘With hindsight’, writes Prentice in the shot list, ‘I am horrified to think that I was so foolish as to take such an important official amongst hippos, crocs and rapids in a small boat powered by a dicey outboard motor!’).

The film begins by showing the foci of onchoceriasis infection in Uganda, and then moves on to a sequence showing a Similium fly biting and feeding from a European arm. Subsequent sequences show the team searching for fly larvae, numerous shots of the general area and the Karuma Falls, and the development and construction of the dosing station (two large pylons, one on each bank, with a perforated pipe running between them, along which the insecticide solution flowed, and was thus sprayed down in to the river). Dangers and obstacles to the project are featured – wildlife (hippopotami and crocodiles), huge floating islands of papyrus grass, swift flowing rapids – and the various stages of the project are clearly delineated. There is also room for a little humour – a slapstick incident where a European trips over is included, and the droll faux-military title ‘Operation Eggwhisk’ is bestowed upon a sequence of Prentice dispersing the solution by swinging the motorboat in tight turns midstream.  

The ‘narrative’ of the film is clear, and the actions of Prentice and his colleagues are usually comprehensible, in keeping with the instructional purpose of the production. Africans are present in almost all scenes of action, from looking for the larval flies to filling the beer cans in the final sequence, and African labourers, boatmen, and assistants evidently had a central role in the execution of the project. However, their presence on screen is secondary to the main role played by Europeans, and they are effectively ignored by the camera. A sequence that begins at 12.20 is particularly telling. The camera, fixed on the bank apparently within the branches of a downed tree, is trained on an approaching motorboat piloted by a solitary European; the boat contains some metal pylon struts. Leaning back on the tree trunk, a young African man, bare-chested, looks first toward the camera, then toward the approaching boat. The boat docks and there is a flurry of activity as the struts are unloaded by Africans waiting at the bank-side. As the boat departs, the African labourers resume their prior positions, the bare-chested man sits back into his earlier position and glances at the camera, and the scene is still once more. But the shot continues until the motorboat, now in the distance, disappears behind a bend in the river, at which point it abruptly cuts. A more eloquent illustration of the contrast between the peripheral status of Africans and the crucial support that the Empire required from African labour could hardly have been scripted. 

Francis Gooding 


Works Cited

Holden, Pat Doctors and Other Medical Personnel In The Public Health Services In Africa 1930-1965 (private report to Oxford Development Records Project, 1984).

Prentice, M. A. ‘Onchocerciasis Control Programme in Uganda’, in Prentice Collection accession files, British Empire and Commonwealth Museum.

Prentice Collection: accession files, British Empire and Commonwealth Museum

‘Onchocerciasis - River Blindness’ British Medical Journal vol. 2, no. 5916 (May 1975), pp. 401-2

World Health Organization: ‘Water Related Diseases - Onchocerciasis’ 



  • Prentice Collection: The Survey & Control of River Blindness (Onchocerciasis) in Uganda 1959 (Archive)
Series Title:
Prentice Collection

Technical Data

Running Time:
30 minutes
Film Gauge (Format):
16mm VHS
approx 720 ft

Production Credits

Production Details
See synopsis