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TREATMENT OF EAST COAST FEVER USING CLEXON IN UGANDA

O. Bwangamoi and C.P. Otim

Animal Health Research Centre,

P.O. Box 24,

Entebbe,

Uganda.

Introduction

Clexon, a trade name for parvaquone is an analogue for menoctone which had earlier been identified as having anti-theilerial activity against Theileria parva in vitro (McHardy, Haigh and Dolan, 1976) and in vivo (Mchardy et al., 1976; Dolan and McHardy, 1978). Unfortunately menoctone was found expensive and complex to synthesise and was not developed. Parvaquone, an active analogue of menoctone, was later shown to control tick stabilate induced infections of T.parva (East Coast Fever) with a single treatment of 20 mg/kg of body weight and was chosen for development (McHardy, Hudson and Rae, 1960).

In a recent trial in Kenya, 92% cattle with East Coast Fever (ECF) recovered after treatment with parvaquone (Wellcome Kenya Limited). The conclusion drawn from that the field trial in Kenya was that parvaquone could be effectively used to treat ECF especially, when the disease was diagnosed early in the febrile state.

The purpose of this trial was to find out the effectiveness of Clexon to different field strains of T.parva in Uganda.

Materials and methods

There were two types of field treatment trials carried out. One involved experimentally induced ECF and the other, natural field infection in Gulu, Mukono, Kampala, Entebbe and Masaka areas.

(1) Experimental ECF in Gulu:

Table 1: Experimental Infection of Cattle from Aswa

SEX

TREATED

UNTREATED

TOTAL

Bulls

5

2

7

Steers

11

2

13

Heifers

12

3

15

TOTAL

28

7

35

(2)Natural field infections

Cattle which naturally contracted ECF in the vicinity of the towns of Gulu, Mukono, Kampala, Entebbe and Masaka (and were reported to us by the owners) were treated with Clexon after confirmation of diagnosi5; as above. There were altogether 69 head of cattle treated and three served a& controls in those areas in Gulu area the cattle treated were all Zebu type aged between 4 and 12 months except one Boran cross; bull calf. In Mukono, Kampala and Entebbe all cattle were adult Friesian; in Masaka the majority were adult Boran heifers, in addition to 5 Ankole Longhorn calves.

Results

There were 97 cattle treated altogether with Clexon and 78.411 survived ECF; however the results differed between experimental find natural infection.

Experimental

In all 46.4% survived ECF after treatment with Clexon as sholin in Table 2.

Table 2: Response to Treatment on Experimental Cattle from Aswa.

SEX

TREATED

DEAD

LOST/DEAD

SURVIVED

Bull

5

2

1

2

Steer

11

9

0

2

Heifer

12

2

1

9

TOTAL

28

13

2*

13** (46.43%)

28.6% of the animals that had to be treated received only one dose, instead of two, and all died. Of the 20 cattle that received the recommended two treatments i.e. full dosage, 65% survived ECF. All the untreated cattle acting as controls died of ECF.

Natural infection

91.3% of all cattle treated after natural infection survived ECF. The results varied from place to place, such as 94.1% in Gulu, 100% in Kampala, Mukono and Entebbe and 86.6% in Masaka as shown in

Tables 3, 4 and 5.

Table 3: Response to Treatment of Farm Cattle - Gulu

SEX

TREATED

DEAD

SLAUGHTERED

SURVIVED

Bull

17

1*

0

16

Steer

16

0

0

16

Heifer

1

0

1

0

TOTAL

34

1

1

32=94.12%

*After 1 month

Table 4: Response to Treatment of Farm Cattle: Kampala, Mukono and Entebbe

SEX

TREATED

DIED

SURVIVED

Bull

1

0

1

Steer

3

0

3

Heifer

1

0

1

Total

5

0

5=100%

Table 5: Response to Treatment of Farm Cattle - Masaka

BREED

TREATED

DIED

SURVIVED

UNTREATED

DIED

SURVIVED

Boran

24

3

21

3

3

0

Boran-Cross

1

1

0

0

0

0

Ankole

5

0

5

0

0

0

TOTAL

30

4

26 (87%)

3

3

0

There was no difference in response to treatment in breed, age and sex. The 4 cattle which died in Masaka had been given one treatment only and were in the advanced stages of ECF. Death occurred within twelve hours of the first treatment. All the untreated cattle died of ECF.

Discussion

78.4% of all animals treated with Clexon survived ECF. However the response was better on individual farms where 91.3% of the cattle survived as opposed to only 46.4% in experimental animals. The reasons for this marked difference was partly due to the fact that in the latter case, 8 beasts hid themselves in the bush after. only a single dose of 10 mg/kg body weight. McHardy et al. (1980) showed that a single injection was effective at 20 mg/kg body weight and it was recommended that the dose be divided into two and be given 46 hours apart. This is supported by the fact that a much higher rate of survival, 65%, was obtained when the experimental cattle were injected twice. Other contributory causes to the poor performance of the cattle from Aswa was fatigue. They walked a distance of 80 kilometers and on arrival were immediately challenged to a high dose of a virulent strain of ECF through the numerous ticks which parasitized them. Add to that, the pasture was poor because the grass, mainly Hyperaenia spp was fully mature and thus lignified. Such adverse conditions must have contributed to the lowering of the resistance of the Aswa cattle. In contrast to that, the field cases occurred on individual farms where the cattle had long been acclimatised and the conditions under which they lived were more conclusive to recovery. The recovery of 91% of the farm cattle after treatment with Clexon compares favourably with that obtained in Kenya (92%).

This trial showed that Clexon is effective for treatment of ECF caused by different strains of Theileria parva in Uganda. However a further trial is necessary to show its potential under harsh conditions such as experienced at Palm Rivers Farm, Opidi.

Acknowledgement

The authors are grateful to Mr. G.M. Odeke, Senior Laboratory Technologist and Mr. Walter Obua, Laboratory Assistant for assisting in the management of the experimental animals. Funds, chemical's, reagents and drugs for this work was supplied by Wellcome (K) Limited.

References

Dolan, T.T. and McHardy, N. (1978). In: "Tick-borne Diseases and their vectors". (Wilde, J.K.H. ed.) pp. 318 University of Edinburgh.

McHardy, N., Haigh, A.J.B. and Dolan, T.T. (1976). Nature 261, 698

McHardy, N., Hudson, A.T. and Rae, D.G. (1980). In: "The in vitro cultivation of pathogens of tropical diseases". p. 149 Schwabe & Co., Basel.

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