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Criterion for inclusion in onchocerciasis control programmes: A reply
TRANSACTIONS
OF THE ROYAL
SOCIETY
OF TROPICAL
MEDICINE
[Correspondence1 Criterion for inclusion grammes
in onchocerciasis
control pro-
In a recent paper by De Sole (1995: Transactions, 89, 224) reference is made to the Onchocerciasis Control Programme (OCP) in West Africa from where the data used in the article were collected. At the time these data were obtained-a collective effort by a group of clinicians in the OCP-the classification method used for onchodermatitis was highly susceptible to inter- and intra-observer variation. This variation was serious enough to suggest to the OCP that, at that time, further dermatological surveys should be abandoned. The OCP was therefore surprised that firm conclusions were based on the analysis of such data by the author without any critical comment on the quality of the data or the consent of the co-workers. It is stated in the article by the author, without any systematic collection of data, that neither onchocercal skin lesions nor pruritus could be considered severebecause they do not cause disability. This statement is based entirely on the personal opinion of the author and is at odds with the scientific results of a recently concluded multi-country study on the importance of onchocereal skin diseasein Africa (WHO, 1995: The importance of onchocercal skin disease: report of a multi-country study.
Geneva: World Health Organization, mimeographed document TDR/AFR/95.1). The OCP finds the conclusions arrived at by the author not only misleading but also unfortunate in that the inherent defects in the data used were not commented on at all by the author. The Programme would therefore like to dissociate itself from the findings and the conclusions drawn in this article. K. Yankum Dadzie Director of the Onchocerciasis Control Programme in West Africa BP.549 Ouagadougou Burkina Faso 24 August 1995
Criterion for inclusion grammes: a reply
in onchocerciasis
control pro-
Dr Dadzie [above] questions the quality of the Onchocerciasis Control Programme (OCP) data used in my paper (De Sole, G., 1995: Transactions, 89,224), stating that the classification used for onchodermatitis was highly susceptible to inter- and intra-observer variation. The observer variation study was conducted by Dr Bayona and myself just after joining the Programme, when we were therefore rather inexperienced, and it was focused
AND HYGIENE
(1996) 90,206
on nodule counting, not on skin lesions. While nodule counting presents objective difficulties, presence or absence of skin lesions is easier to diagnose and less prone to observer variations. In the caseof depigmentation, it is difficult to miss a patch of white skin on a very dark background. The decision to suspend dermatological surveys was based mainly on the secondary importance of these data to the Programme evaluation that concentrated on prevention of onchocercal blindness and the elimination of the parasite reservoir from the human host. Priority was also given to work in the Programme extension areasand the ivermectin programme. My article reported, as a limitation of the data used, the omission of grading the severity of lymphatic and skin lesions. Furthermore, the OCP has a solid reputation for collecting good quality data and Drs Brinkmann and Prost are competent professionals. Dr Dadzie’s observation that the article stated that pruritus cannot be considered severebecauseit does not causedisability is incorrect. The article continued: Pruritus could become so intense as to be temporarily incapacitating. However, in 6 years’ experience with onchocerciasis in West Africa and repeated observation of 400 000 people treated with ivermectin and 300 000 surveyed for epidemiological mapping, pruritus of such intensity has never been seen, not even as a reaction to ivermectin treatment The article’s conclusion was therefore based on recent observations, using the definition of mild, moderate and severe pruritus developed by WHOiTDR for the ivermectin trials. Dr Dadzie participated in this effort and was co-author of 2 publications [cited in Dr De Sole’s paper, lot. cit.] reporting the results of OCP community trials. None of the community trials conducted outside the OCP area by other investigators under the supervision of TDR reDorted severeDruritus as a oroblem. Concerning ihe lack of colworkers’ co;sent, my article’s conclusions are in line with the objective of the epidemiological mapping described in 4 papers of which my co-workers were co-authors [see the references in Dr De Sole’s paper, lot. cit.] and with the Programme’s plan of operations for the fourth financial phase (1992-1997). Finally, if 2 TDR studies with different objectives i.e., ivermectin safety and public health importance of onchocerciasis - report conflicting findings on pruritus, further investigation is needed unless the difference can be explained by bias. For example, did the new studv use a different definition of muritus? The issue shoild be openly discussed allowing’ a forum, as in true science, for all opinions. G. De Sole B. l? 6988 Harare Zimbabwe 6 October 1995
OF THE ROYAL
SOCIETY
OF TROPICAL
MEDICINE
[Correspondence1 Criterion for inclusion grammes
in onchocerciasis
control pro-
In a recent paper by De Sole (1995: Transactions, 89, 224) reference is made to the Onchocerciasis Control Programme (OCP) in West Africa from where the data used in the article were collected. At the time these data were obtained-a collective effort by a group of clinicians in the OCP-the classification method used for onchodermatitis was highly susceptible to inter- and intra-observer variation. This variation was serious enough to suggest to the OCP that, at that time, further dermatological surveys should be abandoned. The OCP was therefore surprised that firm conclusions were based on the analysis of such data by the author without any critical comment on the quality of the data or the consent of the co-workers. It is stated in the article by the author, without any systematic collection of data, that neither onchocercal skin lesions nor pruritus could be considered severebecause they do not cause disability. This statement is based entirely on the personal opinion of the author and is at odds with the scientific results of a recently concluded multi-country study on the importance of onchocereal skin diseasein Africa (WHO, 1995: The importance of onchocercal skin disease: report of a multi-country study.
Geneva: World Health Organization, mimeographed document TDR/AFR/95.1). The OCP finds the conclusions arrived at by the author not only misleading but also unfortunate in that the inherent defects in the data used were not commented on at all by the author. The Programme would therefore like to dissociate itself from the findings and the conclusions drawn in this article. K. Yankum Dadzie Director of the Onchocerciasis Control Programme in West Africa BP.549 Ouagadougou Burkina Faso 24 August 1995
Criterion for inclusion grammes: a reply
in onchocerciasis
control pro-
Dr Dadzie [above] questions the quality of the Onchocerciasis Control Programme (OCP) data used in my paper (De Sole, G., 1995: Transactions, 89,224), stating that the classification used for onchodermatitis was highly susceptible to inter- and intra-observer variation. The observer variation study was conducted by Dr Bayona and myself just after joining the Programme, when we were therefore rather inexperienced, and it was focused
AND HYGIENE
(1996) 90,206
on nodule counting, not on skin lesions. While nodule counting presents objective difficulties, presence or absence of skin lesions is easier to diagnose and less prone to observer variations. In the caseof depigmentation, it is difficult to miss a patch of white skin on a very dark background. The decision to suspend dermatological surveys was based mainly on the secondary importance of these data to the Programme evaluation that concentrated on prevention of onchocercal blindness and the elimination of the parasite reservoir from the human host. Priority was also given to work in the Programme extension areasand the ivermectin programme. My article reported, as a limitation of the data used, the omission of grading the severity of lymphatic and skin lesions. Furthermore, the OCP has a solid reputation for collecting good quality data and Drs Brinkmann and Prost are competent professionals. Dr Dadzie’s observation that the article stated that pruritus cannot be considered severebecauseit does not causedisability is incorrect. The article continued: Pruritus could become so intense as to be temporarily incapacitating. However, in 6 years’ experience with onchocerciasis in West Africa and repeated observation of 400 000 people treated with ivermectin and 300 000 surveyed for epidemiological mapping, pruritus of such intensity has never been seen, not even as a reaction to ivermectin treatment The article’s conclusion was therefore based on recent observations, using the definition of mild, moderate and severe pruritus developed by WHOiTDR for the ivermectin trials. Dr Dadzie participated in this effort and was co-author of 2 publications [cited in Dr De Sole’s paper, lot. cit.] reporting the results of OCP community trials. None of the community trials conducted outside the OCP area by other investigators under the supervision of TDR reDorted severeDruritus as a oroblem. Concerning ihe lack of colworkers’ co;sent, my article’s conclusions are in line with the objective of the epidemiological mapping described in 4 papers of which my co-workers were co-authors [see the references in Dr De Sole’s paper, lot. cit.] and with the Programme’s plan of operations for the fourth financial phase (1992-1997). Finally, if 2 TDR studies with different objectives i.e., ivermectin safety and public health importance of onchocerciasis - report conflicting findings on pruritus, further investigation is needed unless the difference can be explained by bias. For example, did the new studv use a different definition of muritus? The issue shoild be openly discussed allowing’ a forum, as in true science, for all opinions. G. De Sole B. l? 6988 Harare Zimbabwe 6 October 1995