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Incidence of Bovine Cutaneous Streptothricosis in Nigeria
THE BRITISH VETERINARY JOURNAL Vol.
I27
November
No.
I97 I
II
INCIDENCE OF BOVINE CUTANEOUS STREPTOTHRICOSIS IN NIGERIA BY 0 . 0 . 0DUYE AND
D. H.
LLOYD
Department of Veterinary Pathology, University of Ibadan, Ibadan, Nigeria
SUMMARY
The incidence of bovine cutaneous streptothricosis was studied by means of two independent field surveys. The overall incidence varied considerably from herd to herd and district to district, and a definite seasonal variation was found, the incidence being higher during the rainy than during the dry season. It was also shown that bovine cutaneous streptothricosis accounted for more than 50 per cent of all bovine dermatoses in Nigeria at any one time. INTRODUCTION
Cutaneous streptothricosis in cattle is an important disease in West Africa as a whole and in Nigeria in particular. It was regarded as the second most important bacterial disease in cattle, next to bovine contagious pleuropneumonia, by Doutre & Orue (Ig68) at the Abidjan Conference on Agricultural Research Priorities for Economic Development in Mrica. Except for isolated reports of outbreaks of the disease from particular areas or districts there is a lack of information on the extent to which the disease occurs in Nigeria. It follows that there is a wide gap in our knowledge of the economic losses which can be directly or indirectly attributed to this disease. Field studies are currently being carried out in the Department of Veterinary Pathology, University of Ibadan, for the following purposes: (a) to study bovine cutaneous streptothricosis in its various clinical forms in the field; (b) to determine the incidence of the disease and correlate its severity and distribution with the seasons of the year; (c) to establish the incidence of cutaneous streptothricosis in relation to other bovine dermatoses. (An attempt is being made to classify every skin lesion or disease encountered, both clinically and histopathologically.) (d) to obtain skin biopsy samples of cutaneous streptothricosis for histopathological examination, and scabs from clinical cases for the isola-
so6
BRITISH VETERINARY JOURNAL,
I27, I I
tion and identification of Dermatophilus congolensis, the causative agent of this disease. A separate and independent survey was carried out in September Ig68 in the Northern States of Nigeria, excluding North Eastern State, by the Ministry of Agriculture and Natural Resources (MANR) to obtain information on the extent of cutaneous streptothricosis in cattle. The observations made in these two surveys are presented in this report. o attempt is made to describe either macroscopic or microscopic lesions nor will any attempt be made to discuss the bacteriological aspects of the disease. SURVEY METHODS
The University of Ibadan surveys were made at the end of the rains and at the end of the dry season and have so far been restricted to twelve centres in the Northern States, covering dairy, beef and cattle breeding establishments, belonging either to State Governments or private individuals (Table I). Each herd was visited on each survey trip and a thorough examination made of all animals for evidence of any skin disease. Where skin disease was present which could not be easily classified clinically, a skin biopsy sample was taken for histopathological examination. The Ministry of Agriculture and Natural Resources survey was carried out by means of a proforma sheet sent to the field officials, mainly Livestock Assistants and some Field Overseers. Each official was asked to select about twenty herds in his area for survey. RESULTS
The University of Ibadan survey Table I shows the incidence of bovine cutaneous streptothricosis as observed in the survey centres visited. Six centres were covered in the early stages of the survey; more centres were added later. There was great variation in the incidence of the disease in the various centres, ranging from nil in one herd to 25 per cent of the animals in another being affected. The highest total incidence found was 6·I6 per cent in October/November, Ig68 and the lowest incidence, I ·84 per cent in February/March, 1970, establishing a definite seasonal variation in the incidence of this disease, with a higher prevalence at the end of the wet season than at the end of the dry season. Cases observed during the end of dry season survey were usually very mild, most affected animals showing very few lesions, many of which appeared to be healing. Cases seen at the end of the wet season were more severe and generalized with little or no evidence of healing. At any one time cutaneous streptothricosis accounted for a major part (usually over 50 per cent) of all bovine skin diseases observed during these field surveys (see Fig. I and Table II). It was followed by demodectic mange infection. A newly recognized dermatosis encountered during these surveys was Stephanofilaria! dermatitis, caused by a filarid nematode worm. So far, this has only been observed at one of the survey centres, PagolawafDambata
TABLE I INCIDENCE OF BOVINE CUTANEOUS STREPTOTHRICOSIS
Borflu Cattle Ranch *
(M )
Pagolawa/Dambata Kano State (P)
FEB.
OCT./NOV.
1968
1969
1969
Total Animals
Survey centres (B)
OCT./NOV.
No. affected
500
120
425
No. affected
Total animals
No. affected
360
75
1970
78
Total animals
57 2
No. affected
19
0:;
G
<: I-<
Z
tT:I
0
1806
1600
600
70 0
153
21
0
"
(D)
Shika Experimental Station*
(B)
LIBO, Kabomo*
(D)
Vet. Field Station, Mando Road, Kaduna *
80
Fed. Dept. Vet. Res. Vom*
300
(D)
Total animals
FEB./MAR.
65
2060
83
1135
17
700
0
650
16
600
0
140
14
169
2
139
0
95 33 0
0
89
3
0
0
220
18
76 260
28 4
3
20 5
9
~~
0 C
C/)
0
(M )
Katsina (P)
(M)
Dutsengura via Jos (P)
18 9 280
15
(M )
LIBC, Birnin Kebbi Dogndaji, Bakura and Talata Mafara*
553
16
Total
C >-l
3
C/)
>-l
Gl '"0
>-l 0 >-l ~
3439
212 6'16
Percentage B
Beef herd
D
Dairy herd
M = Mixed beef and dairy herds
3574
157
3753
4'4
209 5'57
3804
iO
I-<
0
70
0C/) I-< C/)
1·84
"Not visited *
State-owned herds
P
Private individual herds (J1
0
'-J
BRITISH VETERINARY JOURNAL, I27, II
so8
in Kano State (Table II). It is not uncommon to find Besnoitia cysts in microscopic sections both of cutaneous streptothricosis and of demodectic mange lesions in the bovine but cutaneous besnoitiosis per se has not been observed in the field. TABLE II BOVINE CUTANEOUS STREPTOTHRICOSIS INCIDENCE IN RELATION TO OTHER BOVINE DERMATOSES
Total no. of animals examined
Period of survry
Oct./Nov 1968
3439
Feb. 1969
3574
Oct.JNov. 1969
3753
Feb./Mar. I970
Total rw . of skin lesions 254 (7'39) 237 (6·63) 348 (9'27) I84 (4·84)
3804
Streptothricosis
Nodular (demodectic ) mange
212 (6· I6) 157 (4 '4) 209 (5"57) 70 (r ·84)
Papilloma
17 (o·so) 51 (1 '43) II9 (3· I 7)
I3 (o·35)
75 (1'97)
9 (0•24)
Stepharwfilarial dermatitis
4 (0•1 I) 3 (o·o8)
II (0'32) 15 (0'42) (?) 29 (0•76)
Note: Figures in brackets denote percentage of total animals examined. *Unclassified skin lesions. BOVINE CUTANEOUS STREPTOTHRICOSIS: Incidence in relation to other Bovine Dermatosn.
8
0 Streptothricosis §
7
Demodectic Mange
!iii Papilloma liD Stephanotilari al Dermatitis I Others
0 11.1
...
(J
w
u.. u..
< 1/)
..J
<
::E
z <4
u.. 0
w C)
... < z
w
u w
"'
0...2
Oct.-Nov. 1968
Feb.-Mar. 1969 PERIOD
Oct .-Nov. 1969 OF
Fig.
SURVEY I.
Feb.-Mar. 1970
Others•
IO (o·29) II (o·3o8) 7 (o· Ig) I
(o·o3)
BOVINE CUTANEOUS STREPTOTHRICOSIS
509
The Ministry of Agriculture and Natural Resources (Northern States) survey The overall percentage rate of infection ( 10·44 per cent) appeared to be very high (Table III), Kano State having the highest percentage of infection and Benue Plateau State the lowest. There are great variations in the incidence when viewed on a provincial basis. TABLE III ANALYSIS OF STREPTOTHRICOSIS SURVEY CONDUCTED BY M.A.N.R. (NORTHERN STATES) SEPTEMBER I g68
State
Kwara
North-Western
North-Central
Province or area
Total no. of animals examined
Total no. of affected animals
IIorin Kabba
I4IO I655
85 234
6 I4
3065*
3I9*
I0'4*
Sokoto Niger
Katsina Zaria
Kano
Benue-Plateau
•=
Plateau Benue North Benue South
Total figure for each State.
t
=
Percentage affected
28524 10550
3I40 1528
II 14'4
39074*
4668•
II·g*
1788 17298
272 1304
I5'2 7'5
19086*
1576*
8·2·
11127*
1406•
12·63*
4496 6g87 3255
358 661 100
8 9'4 3'1
14698*
1119*
7·5•
87o5ot
go88t
10'44t
Total figure for all States.
DISCUSSION
These findings are not presented as the final and complete picture of the disease position in the field. It is intended as a preliminary report and it is proposed to continue these surveys for another three to four years. It should then be possible to give an accurate assessment of the incidence of this very important disease which will take account of the annual and seasonal fluctuations observed in the field. The observed differences between the University of Ibadan survey and the Ministry of Agriculture and Natural Resources survey of Ig68 are significant. The overall percentage incidence as indicated by the former is 6· I 6 per cent whereas in the latter it is as high as I0'44 per cent, a difference of about 40 per cent. This discrepancy can be explained in a number of ways. Firstly, the Ministry of Agriculture and Natural Resources survey was made shortly after the peak of the rainy season which is a period of high incidence of cutaneous streptothricosis (Lloyd and Oduye, in preparation). The University of Ibadan surveys were made at the end of the rains when regression of clinical cases had started to take place.
·510
BRITISH VETERINARY JOURNAL, 127, II
Secondly, it is possible that many of the animals affected irt September were culled or had died before the October/November survey was carried out. Thirdly, some of the personnel employed in the September rg68 Ministry of Agriculture and Natural Resources survey clearly misunderstood the ·questionnaires. It has since been discovered that some of them regarded every skin lesion as cutaneous streptothricosis. It is therefore probable that the figures obtained at that time were somewhat inflated. All three features mentioned are obviously involved to some extent. An assessment of the relative importance of each must await further investigation. ACKNOWLEDGEMENTS
The authors would like to acknowledge the invaluable asssitance of the Chief Veterinary Officers of the Northern States and in particular Dr. D. A. W. Walker, Co-ordinating Chief Veterinary Officer, in providing the data from the Ministry of Agriculture and Natural Resources Survey and for their help during the University of Ibadan seasonal surveys. The University of Ibadan surveys were supported by a grant from the Foreign and Commonwealth Office, Overseas Development Administration, London. REFERENCES
DouTRE, M. & 0RUE, J. (I 968). Agricultural Research Priorities for Economic Development in Africa. The Abidjan Conference, I968. Vol. III, p. 146. (Accepted for publication 9 January 197I ) Incidence de Ia streptothricose cutanee bovine au Nigeria (Oduye et Lloyd) Resu:rne. On a etudie !'incidence de !a streptothricose cutanee bovine au moyen de deux enquetes independantes menees dans les champs. L'incidence totale varie considerablement de troupeau a troupeau et de district a district, et on a trouve une reelle variation saisonniere, !'incidence etant plus elevee pendant Ia saison des pluies que pendant !a saison seche. On a aussi montre que Ia streptothricose cutanee etait responsable de plus de 50 pour cent de toutes les dermatoses bovines au Nigeria a n'importe que! moment. Auftreten kutaner Streptothrikose bei Rindern in Nigeria (Odue und Lloyd) Zusa:rn:rnenfassung. Das Auftreten kutaner Streptothrikose bei Rindern wurde mit Riffe von zwei selbsUindigen Untersuchungsreihen studiert. Das Gesamtvorkommen variierte erheblich in individ1,1ellen Herden und Distrikten. Ausserdem · wurde eine definitive Abhangigkeit von der Jahreszeitbemerkt: die Haufigkeit wahrend der Regenzeit war grosser ·als in der trockenen Jahreszeit. Ferner stellte sich heraus, class die kutane Streptothrikose fiir mehr als 50 prozent aller Dermatosen der nigerischen Rinder verantwortlich ist ·und zwar zu jeder Z eit. lncidencia de Ia estreptotricosis cutanea bovina en Nigeria (04uye y Lloyd) Resu:rnen. Se estudi6 la incidencia de la estreptotricosis cutanea bovina valiendose de dos estudios de campo independientes. La incidencia total vari6 ampliamente de manada a manada y de distrito a distrito, encontrandose una variaci6n estacional definida, de modo que Ia incidencia fue decididamente mayor durante !a estaci6n de las lluvias que ·en !a estaci6n seca. Se demostr6 tambien que !a estreptotricosis cutanea bovina representaba mas del 50 por ciento de todas las dermatosis bovinas en Nigeria en cualquier epoca del aiio.
I27
November
No.
I97 I
II
INCIDENCE OF BOVINE CUTANEOUS STREPTOTHRICOSIS IN NIGERIA BY 0 . 0 . 0DUYE AND
D. H.
LLOYD
Department of Veterinary Pathology, University of Ibadan, Ibadan, Nigeria
SUMMARY
The incidence of bovine cutaneous streptothricosis was studied by means of two independent field surveys. The overall incidence varied considerably from herd to herd and district to district, and a definite seasonal variation was found, the incidence being higher during the rainy than during the dry season. It was also shown that bovine cutaneous streptothricosis accounted for more than 50 per cent of all bovine dermatoses in Nigeria at any one time. INTRODUCTION
Cutaneous streptothricosis in cattle is an important disease in West Africa as a whole and in Nigeria in particular. It was regarded as the second most important bacterial disease in cattle, next to bovine contagious pleuropneumonia, by Doutre & Orue (Ig68) at the Abidjan Conference on Agricultural Research Priorities for Economic Development in Mrica. Except for isolated reports of outbreaks of the disease from particular areas or districts there is a lack of information on the extent to which the disease occurs in Nigeria. It follows that there is a wide gap in our knowledge of the economic losses which can be directly or indirectly attributed to this disease. Field studies are currently being carried out in the Department of Veterinary Pathology, University of Ibadan, for the following purposes: (a) to study bovine cutaneous streptothricosis in its various clinical forms in the field; (b) to determine the incidence of the disease and correlate its severity and distribution with the seasons of the year; (c) to establish the incidence of cutaneous streptothricosis in relation to other bovine dermatoses. (An attempt is being made to classify every skin lesion or disease encountered, both clinically and histopathologically.) (d) to obtain skin biopsy samples of cutaneous streptothricosis for histopathological examination, and scabs from clinical cases for the isola-
so6
BRITISH VETERINARY JOURNAL,
I27, I I
tion and identification of Dermatophilus congolensis, the causative agent of this disease. A separate and independent survey was carried out in September Ig68 in the Northern States of Nigeria, excluding North Eastern State, by the Ministry of Agriculture and Natural Resources (MANR) to obtain information on the extent of cutaneous streptothricosis in cattle. The observations made in these two surveys are presented in this report. o attempt is made to describe either macroscopic or microscopic lesions nor will any attempt be made to discuss the bacteriological aspects of the disease. SURVEY METHODS
The University of Ibadan surveys were made at the end of the rains and at the end of the dry season and have so far been restricted to twelve centres in the Northern States, covering dairy, beef and cattle breeding establishments, belonging either to State Governments or private individuals (Table I). Each herd was visited on each survey trip and a thorough examination made of all animals for evidence of any skin disease. Where skin disease was present which could not be easily classified clinically, a skin biopsy sample was taken for histopathological examination. The Ministry of Agriculture and Natural Resources survey was carried out by means of a proforma sheet sent to the field officials, mainly Livestock Assistants and some Field Overseers. Each official was asked to select about twenty herds in his area for survey. RESULTS
The University of Ibadan survey Table I shows the incidence of bovine cutaneous streptothricosis as observed in the survey centres visited. Six centres were covered in the early stages of the survey; more centres were added later. There was great variation in the incidence of the disease in the various centres, ranging from nil in one herd to 25 per cent of the animals in another being affected. The highest total incidence found was 6·I6 per cent in October/November, Ig68 and the lowest incidence, I ·84 per cent in February/March, 1970, establishing a definite seasonal variation in the incidence of this disease, with a higher prevalence at the end of the wet season than at the end of the dry season. Cases observed during the end of dry season survey were usually very mild, most affected animals showing very few lesions, many of which appeared to be healing. Cases seen at the end of the wet season were more severe and generalized with little or no evidence of healing. At any one time cutaneous streptothricosis accounted for a major part (usually over 50 per cent) of all bovine skin diseases observed during these field surveys (see Fig. I and Table II). It was followed by demodectic mange infection. A newly recognized dermatosis encountered during these surveys was Stephanofilaria! dermatitis, caused by a filarid nematode worm. So far, this has only been observed at one of the survey centres, PagolawafDambata
TABLE I INCIDENCE OF BOVINE CUTANEOUS STREPTOTHRICOSIS
Borflu Cattle Ranch *
(M )
Pagolawa/Dambata Kano State (P)
FEB.
OCT./NOV.
1968
1969
1969
Total Animals
Survey centres (B)
OCT./NOV.
No. affected
500
120
425
No. affected
Total animals
No. affected
360
75
1970
78
Total animals
57 2
No. affected
19
0:;
G
<: I-<
Z
tT:I
0
1806
1600
600
70 0
153
21
0
"
(D)
Shika Experimental Station*
(B)
LIBO, Kabomo*
(D)
Vet. Field Station, Mando Road, Kaduna *
80
Fed. Dept. Vet. Res. Vom*
300
(D)
Total animals
FEB./MAR.
65
2060
83
1135
17
700
0
650
16
600
0
140
14
169
2
139
0
95 33 0
0
89
3
0
0
220
18
76 260
28 4
3
20 5
9
~~
0 C
C/)
0
(M )
Katsina (P)
(M)
Dutsengura via Jos (P)
18 9 280
15
(M )
LIBC, Birnin Kebbi Dogndaji, Bakura and Talata Mafara*
553
16
Total
C >-l
3
C/)
>-l
Gl '"0
>-l 0 >-l ~
3439
212 6'16
Percentage B
Beef herd
D
Dairy herd
M = Mixed beef and dairy herds
3574
157
3753
4'4
209 5'57
3804
iO
I-<
0
70
0C/) I-< C/)
1·84
"Not visited *
State-owned herds
P
Private individual herds (J1
0
'-J
BRITISH VETERINARY JOURNAL, I27, II
so8
in Kano State (Table II). It is not uncommon to find Besnoitia cysts in microscopic sections both of cutaneous streptothricosis and of demodectic mange lesions in the bovine but cutaneous besnoitiosis per se has not been observed in the field. TABLE II BOVINE CUTANEOUS STREPTOTHRICOSIS INCIDENCE IN RELATION TO OTHER BOVINE DERMATOSES
Total no. of animals examined
Period of survry
Oct./Nov 1968
3439
Feb. 1969
3574
Oct.JNov. 1969
3753
Feb./Mar. I970
Total rw . of skin lesions 254 (7'39) 237 (6·63) 348 (9'27) I84 (4·84)
3804
Streptothricosis
Nodular (demodectic ) mange
212 (6· I6) 157 (4 '4) 209 (5"57) 70 (r ·84)
Papilloma
17 (o·so) 51 (1 '43) II9 (3· I 7)
I3 (o·35)
75 (1'97)
9 (0•24)
Stepharwfilarial dermatitis
4 (0•1 I) 3 (o·o8)
II (0'32) 15 (0'42) (?) 29 (0•76)
Note: Figures in brackets denote percentage of total animals examined. *Unclassified skin lesions. BOVINE CUTANEOUS STREPTOTHRICOSIS: Incidence in relation to other Bovine Dermatosn.
8
0 Streptothricosis §
7
Demodectic Mange
!iii Papilloma liD Stephanotilari al Dermatitis I Others
0 11.1
...
(J
w
u.. u..
< 1/)
..J
<
::E
z <4
u.. 0
w C)
... < z
w
u w
"'
0...2
Oct.-Nov. 1968
Feb.-Mar. 1969 PERIOD
Oct .-Nov. 1969 OF
Fig.
SURVEY I.
Feb.-Mar. 1970
Others•
IO (o·29) II (o·3o8) 7 (o· Ig) I
(o·o3)
BOVINE CUTANEOUS STREPTOTHRICOSIS
509
The Ministry of Agriculture and Natural Resources (Northern States) survey The overall percentage rate of infection ( 10·44 per cent) appeared to be very high (Table III), Kano State having the highest percentage of infection and Benue Plateau State the lowest. There are great variations in the incidence when viewed on a provincial basis. TABLE III ANALYSIS OF STREPTOTHRICOSIS SURVEY CONDUCTED BY M.A.N.R. (NORTHERN STATES) SEPTEMBER I g68
State
Kwara
North-Western
North-Central
Province or area
Total no. of animals examined
Total no. of affected animals
IIorin Kabba
I4IO I655
85 234
6 I4
3065*
3I9*
I0'4*
Sokoto Niger
Katsina Zaria
Kano
Benue-Plateau
•=
Plateau Benue North Benue South
Total figure for each State.
t
=
Percentage affected
28524 10550
3I40 1528
II 14'4
39074*
4668•
II·g*
1788 17298
272 1304
I5'2 7'5
19086*
1576*
8·2·
11127*
1406•
12·63*
4496 6g87 3255
358 661 100
8 9'4 3'1
14698*
1119*
7·5•
87o5ot
go88t
10'44t
Total figure for all States.
DISCUSSION
These findings are not presented as the final and complete picture of the disease position in the field. It is intended as a preliminary report and it is proposed to continue these surveys for another three to four years. It should then be possible to give an accurate assessment of the incidence of this very important disease which will take account of the annual and seasonal fluctuations observed in the field. The observed differences between the University of Ibadan survey and the Ministry of Agriculture and Natural Resources survey of Ig68 are significant. The overall percentage incidence as indicated by the former is 6· I 6 per cent whereas in the latter it is as high as I0'44 per cent, a difference of about 40 per cent. This discrepancy can be explained in a number of ways. Firstly, the Ministry of Agriculture and Natural Resources survey was made shortly after the peak of the rainy season which is a period of high incidence of cutaneous streptothricosis (Lloyd and Oduye, in preparation). The University of Ibadan surveys were made at the end of the rains when regression of clinical cases had started to take place.
·510
BRITISH VETERINARY JOURNAL, 127, II
Secondly, it is possible that many of the animals affected irt September were culled or had died before the October/November survey was carried out. Thirdly, some of the personnel employed in the September rg68 Ministry of Agriculture and Natural Resources survey clearly misunderstood the ·questionnaires. It has since been discovered that some of them regarded every skin lesion as cutaneous streptothricosis. It is therefore probable that the figures obtained at that time were somewhat inflated. All three features mentioned are obviously involved to some extent. An assessment of the relative importance of each must await further investigation. ACKNOWLEDGEMENTS
The authors would like to acknowledge the invaluable asssitance of the Chief Veterinary Officers of the Northern States and in particular Dr. D. A. W. Walker, Co-ordinating Chief Veterinary Officer, in providing the data from the Ministry of Agriculture and Natural Resources Survey and for their help during the University of Ibadan seasonal surveys. The University of Ibadan surveys were supported by a grant from the Foreign and Commonwealth Office, Overseas Development Administration, London. REFERENCES
DouTRE, M. & 0RUE, J. (I 968). Agricultural Research Priorities for Economic Development in Africa. The Abidjan Conference, I968. Vol. III, p. 146. (Accepted for publication 9 January 197I ) Incidence de Ia streptothricose cutanee bovine au Nigeria (Oduye et Lloyd) Resu:rne. On a etudie !'incidence de !a streptothricose cutanee bovine au moyen de deux enquetes independantes menees dans les champs. L'incidence totale varie considerablement de troupeau a troupeau et de district a district, et on a trouve une reelle variation saisonniere, !'incidence etant plus elevee pendant Ia saison des pluies que pendant !a saison seche. On a aussi montre que Ia streptothricose cutanee etait responsable de plus de 50 pour cent de toutes les dermatoses bovines au Nigeria a n'importe que! moment. Auftreten kutaner Streptothrikose bei Rindern in Nigeria (Odue und Lloyd) Zusa:rn:rnenfassung. Das Auftreten kutaner Streptothrikose bei Rindern wurde mit Riffe von zwei selbsUindigen Untersuchungsreihen studiert. Das Gesamtvorkommen variierte erheblich in individ1,1ellen Herden und Distrikten. Ausserdem · wurde eine definitive Abhangigkeit von der Jahreszeitbemerkt: die Haufigkeit wahrend der Regenzeit war grosser ·als in der trockenen Jahreszeit. Ferner stellte sich heraus, class die kutane Streptothrikose fiir mehr als 50 prozent aller Dermatosen der nigerischen Rinder verantwortlich ist ·und zwar zu jeder Z eit. lncidencia de Ia estreptotricosis cutanea bovina en Nigeria (04uye y Lloyd) Resu:rnen. Se estudi6 la incidencia de la estreptotricosis cutanea bovina valiendose de dos estudios de campo independientes. La incidencia total vari6 ampliamente de manada a manada y de distrito a distrito, encontrandose una variaci6n estacional definida, de modo que Ia incidencia fue decididamente mayor durante !a estaci6n de las lluvias que ·en !a estaci6n seca. Se demostr6 tambien que !a estreptotricosis cutanea bovina representaba mas del 50 por ciento de todas las dermatosis bovinas en Nigeria en cualquier epoca del aiio.