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Diseases of small ruminants in central Tanzania

L.E.G. Mboera1 and J.I. Kitalyi2

1Livestock Training Institute P.O. Box 51, Mpwapwa, Tanzania
2Veterinary Investigation Centre P.O. Box 159, Mpwapwa, Tanzania


Abstract
Introduction
Materials and methods
Results
Discussion
Conclusions
References


Abstract

Information on diseases affecting small ruminants in Tanzania has not been extensively documented. More than 14 years' worth of data on disease cases in sheep and goats was analysed from records kept at the Veterinary Investigation Centre (VIC) and Livestock Training Institute (LTI), Mpwapwa. Results showed that the majority of the disease cases were parasitic infections (53.1%), followed by bacterial infections (23.6%), other infectious diseases (12.6%) and non-infectious conditions (10.7%).

This study shows that the diseases affecting sheep and goats in Tanzania, particularly the central zone, need to be diagnosed and documented in order to implement more effective disease control measures.

Pathologie des petits ruminants en Tanzanie centrale

Résumé

Il existe peu d'études sur la pathologie des petits ruminants en Tanzanie. Des données sur les cas de maladies relevés pendant plus de 14 ans sur des ovins et des caprins au Centre de recherche vétérinaire et à l'Institut de formation en élevage de Mpwapwa ont été analysées. Les maladies les plus répandues étaient les parasitoses (53,1%), suivies des maladies bactériennes (23,6%) et d'autres maladies infectieuses (12,6%) et non infectieuses (10, 7%).

Cette étude fait ressortir la nécessité de diagnostiquer et de répertorier les maladies qui frappent les petits ruminants en Tanzanie, particulièrement dans la zone centrale, en vue de la mise en place de mesures efficaces de prophylaxie.

Introduction

Among the many constraints which limit productivity in livestock populations, disease and parasites are of major importance. In Africa, however, little is known about small ruminant diseases and parasites.

In Tanzania there is a dearth of information on specific causes of sheep and goat mortality and morbidity. Several reports have been written on livestock diseases in the country, but with very little attention to small ruminant diseases. Nyange (1984) mentioned the incidences of diseases such as caprine pleuropneumonia and sheep pox in northern Tanzania. while Mbise et al (1984) reported incidences of anthrax and brucellosis. Matovelo et al (1987) reported that parasitic gastroenteritis, pneumonia and diarrhoea were the dominant problems in small ruminants in the eastern part of the country.

Control of animal diseases is essential for realising the potential of small ruminant production. For proper control to be instituted, however, diseases and their dynamics must be known. This paper reports disease findings for cases brought to the Veterinary Investigation Centre (VIC) and Livestock Training Institute (LTI) laboratories at Mpwapwa for routine diagnosis between 1978 and 1991.

Materials and methods

The area covered in the study is the central zone of Tanzania. The zone lies roughly between latitudes 4° and 8°S and longitudes 32° and 39°E. It is predominantly a livestock area occupied by sedentary pastoralists. There are approximately half a million sheep and 1.2 million goats in this zone, representing about 16 and 18%, respectively, of the total small ruminant population in the country. The sheep and goats are predominantly local breeds which are usually kept extensively.

The data was collected from records of cases diagnosed at the VIC and LTI laboratories. Sheep and goats have been grouped together. The data reported are either confirmed diagnoses or conclusions. The methods used in diagnosis were clinical examination, post-mortem findings and laboratory tests such as bacterial cultures and serological tests.

Results

Table 1 shows the major diseases identified and their prevalence.

Table 1. Diseases diagnosed in small ruminants classified by major aestological groups.

Disease group

Number of diagnoses

Per cent of total diagnoses

Parasitic infections

278

53.1

Bacterial infections

124

23.6

Other infectious diseases

66

12.6

Non-infectious diseases

56

10.7

Total

524

100.0

Of the parasitic infections, helminthiasis was the most common (Table 2). Coccidiosis, flea (Ctenocephalides canis) infestation and Oestrus ovis larvae infestation were other parasitic infections diagnosed in high incidences. Mange and anaplasmosis, though in lower incidences, were also reported.

Bacterial infections ranked second in the diseases affecting small ruminants (Table 1). There were high incidences of foot rot, abscess, pneumonia and dermatophilosis (Table 3). Other bacterial diseases occasionally diagnosed included anthrax, pasteurellosis, streptococcosis, mastitis, caseous lymphadenitis, tetanus, colibacillosis and brucellosis.

Table 2. Parasitic infections diagnosed in small ruminants.

Disease condition

Number of diagnoses

Per cent

Helminthiasis

278

64.4

Coccidiosis

52

18.7

Flea infestation

27

9.7

Oestrus ovis

12

4.3

larvae infestation



Mange

5

1.8

Anaplasmosis

3

1.1

Table 3. Bacterial diseases diagnosed in small ruminants.

Disease condition

Number of diagnoses

Per cent

Foot rot

47

37.9

Abscess

26

21.0

Pneumonia

24

19.4

Dermatophilosis

11

8.9

Anthrax

4

3.2

Pasteurellosis

3

2.4

Streptococcosis

2

1.6

Mastitis

2

1.6

Caseous lymphadenitis

2

1.6

Tetanus

1

0.8

Colibacillosis

1

0.8

Brucellosis

1

0.8

Table 4 shows other infectious diseases, including viral, fungal and systemic diseases for which the etiological agent could not be determined. In this group, incidences of caprine ophthalmia had the highest frequency. Contagious ecthyma (orf) was the only viral disease reported in this study. Dermatomycosis was the only fungal disease reported in the area.

Table 4. Other infectious diseases diagnosed in small ruminants.

Disease condition

Number of diagnoses

Per cent

Caprine ophthalmia

28

42.4

Contagious ecthyma

21

31.9

Enteritis

9

13.6

Dermatomycosis

6

9.1

Peritonitis

2

3.0

Table 5. Non-infections disease conditions diagnosed in small ruminants.

Disease condition

Number of diagnoses

Per cent

Fracture

15

26.7

Wounds

10

17.8

Poisoning

9

16.1

Dystocia

5

8.9

Retained placenta

4

7.1

Stillbirth

3

5 4

Senility

3

5.4

Starvation

2

3.6

Hernia

2

3.6

Abortion

2

3.6

Rectal perforation

1

1.8

Fractures, wounds and poisoning were the commonest non-infectious conditions (Table 5). Reproductive problems such as abortion, dystocia, stillbirth and retained placenta were recorded. Hernia, senility and rectal perforation were also observed.

Discussion

In small ruminants, the majority of diseases reported in central Tanzania were parasitic infections with helminthiasis and coccidiosis being the most prevalent. Matovelo et al (1987) observed that the diagnosed disease conditions affecting sheep and goats in the eastern part of the country were mainly parasitic gastroenteritis.

The economic impact of helminthiasis is enormous. Herlich (1978) estimated that the total animal loss due to helminthiasis worldwide is equivalent to 30 million goats and sheep. Constraints to animal production attributable to helminthiasis include inefficient food conversion, poor growth and reduced fertility.

Protozoan diseases of small ruminants have received very little attention in Tanzania. Coccidiosis has been reported as the major protozoan disease of small ruminants in the region. Other protozoan diseases of small ruminants have been reported in the country. Toxoplasmiosis has been diagnosed serologically in southern Tanzania (Connor et al, 1985 as cited by Otaru, 1985), whereas trypanosomiasis has been reported in the eastern part of the country (Matovelo et al, 1987).

Ectoparasitism accounted for about 15.8% of the parasitic diseases reported in this study. Of the ectoparasites, Ctenocephalides canis appears to be the most important in the region. Fleas have been reported to occur in sheep and goats in other areas of the country. Kilonzo and Khama (1989) observed that goats and sheep in north-east Tanzania were heavily infested with the cat flea Ctenocephalides felis. General infestation of sheep and goats by fleas produces debilitating effects on their hosts. Heavily infested goats and sheep are weak, anaemic and emaciated. Heavy flea infestation of lambs and kids may cause death.

Oestrus ovis larvae infestation was the second most prevalent ectoparasitism in small ruminants. O. ovis larvae infestation has also been recorded elsewhere in Tanzania (Matovelo et al, 1987). The larvae at the nostrils of sheep or goats annoy the animals and cause them to avoid the fly and seek shelter. Snorting, stamping of the feet and shaking of the head are common. Such actions interfere with normal grazing/browsing. The spiny surface of Oestrus ovis larvae causes irritation of the nasal mucosa resulting in sneezing, mucopurulent discharge and difficult, snoring respiration. Oestrus ovis may deposit larvae in the eye, nose or on the lips of man and is thus an important myiasis in some countries (Blood et al, 1983).

Mange is another important ectoparasitic infection diagnosed in sheep and goats in central Tanzania. The disease has been reported to occur in other areas of the country (Matovelo et al, 1987). Mange can be a very stubborn condition, particularly in goats, causing much damage to the skin.

Bacterial diseases were the second most prevalent diseases of small ruminants in central Tanzania. Of the specific bacterial diseases, foot rot was the most prevalent. Most outbreaks occur during the warm and wet months of the year. In serious outbreaks, lameness may be so severe that many animals are forced to walk on their knees.

Although pneumonia and abscess have been reported with higher incidences, in many cases they have been due to non-specific bacteria. Pasteurella species, however, were isolated in three cases of pneumonia. Several investigations have reported Pasteurella organisms as causing some types of pneumonia in goats (Ngatia et al, 1989). Dermatophilosis was another prevalent disease of small ruminants. Outbreaks have frequently been reported in the region (TVA, 1991).

Though figures of anthrax reported in this study are not very significant, outbreaks killing several hundred cattle, sheep and goats have been reported in northern Tanzania (Mbise et al, 1984). Brucellosis is a cause of abortion and infertility in small ruminants (Tekelye and Kasali, 1990). Although only one case of brucellosis was reported from the viewpoint of human health, the disease is important because the causative organism causes human brucellosis when fresh milk from infected goats or sheep is consumed or when direct contact is made with infected placenta following abortion.

Caseous lymphadenitis, colibacillosis, mastitis, streptococcosis and tetanus are also important bacterial diseases of sheep and goats. Caseous lymphadenitis is usually clinically unapparent and is observed during post-mortem examination. It causes high economic losses through condemnation of affected carcasses and organs at slaughter and through losses in production and reproduction (Kuria and Ngatia, 1990). Few cases of mastitis in small ruminants have been reported in other areas of the country (Madsen and Mtenga, 1989).

Of the other infectious diseases, caprine ophthalmia and contagious ecthyma have been reported with higher frequencies. Caprine ophthalmia causes ocular pain and poor vision, so affected goats do not eat properly and fail to thrive. Where treatment is delayed, affected goats become blind. Blind goats are difficult to move and are often discriminated against when they are sold at auction. Contagious ecthyma causes some economic losses. It appears to be endemic in the region as many farmers have complained of several outbreaks in their flocks.

In the other infectious diseases group, enteritis, dermatomycosis and peritonitis were also reported. Enteritis is in most cases manifested by diarrhoea Although enteritis was reported in few cases in this study, reports from eastern regions of the country have shown that diarrhoea is one of the dominant problems for small ruminants (Matovelo et al, 1987). Dermatomycosis of animal origin may affect humans and its diagnosis and treatment are often difficult (Blood et al, 1983).

There are many non-infectious diseases of sheep and goats which result in the animal's death and cause great economic losses, but have not received sufficient attention. Fractures, wounds, poisoning and dystocia represent the largest proportion of conditions in this group. Reproductive disorders such as abortion, dystocia, retained placenta and stillbirth contribute highly to flock infertility. Stillbirth and dystocia appear to be among the primary causes of pre-and perinatal lamb and kid losses in the area. The economic losses attributable to injuries such as fractures, wounds and rectal perforation are difficult to assess owing to the limited data available on their incidence, prevalence, morbidity and mortality rates. However, expenses charged in treatment and nursing may result in large economic losses.

Conclusions

It can therefore be concluded that helminthiasis, coccidiosis, foot rot, caprine ophthalmia, flea infestation and pneumonia are the major specific diseases affecting small ruminants in central Tanzania. Although similar diseases have been reported in other parts of the country, their relative frequency and economic importance have not been assessed. In the absence of reliable epidemiological and economic data, it is impossible to quantify precisely the losses incurred as a result of small ruminant diseases in Tanzania. Although these have been recorded at low incidences, the stock owners do not recognise early clinical signs. Consequently they are late in seeking veterinary advice and suffer losses through lack of timely treatment.

References

Blood D C, Radostitis O M and Henderson J A. 1983. Veterinary medecine. 6th ed. Bailleurs Tindall, London, UK. 1310 pp.

Herlich H. 1978. The importance of helminth infections in ruminants. World Animal Review 26:26-29.

Kilonzo B S and Khama L R S. 1989. The effects of goats' (Capra hircus) age and sex on flea infestation in Tanzania. Bulletin of Animal Health and Production in Africa 37:61-66.

Kuria J K N and Ngatia T A. 1990. Caseous lymphadenitis of sheep and goats in Kenya. Bulletin of Animal Health and Production in Africa 38: 15-18.

Madsen A and Mtenga L A. 1989. Dairy goats successfully introduced in Tanzania. ILCA Newsletter 8(4):9. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia.

Matovelo J A, Semuguruka W D, Mella P N P and Mwamengele G L M. 1987. Some indications on the animal disease status in Tanzania. In: Proceedings of the 5th Tanzania Veterinary Association Scientific Conference held at Arusha International Conference Centre, 1st-3rd December 1987. Tanzania Veterinary Association/Sokoine University of Agriculture, Faculty of Veterinary Medicine, Morogoro, Tanzania. 5: pp. 151-163.

Mbise A N. Nyange I F C and Mbasha E M S. 1984. An outbreak of anthrax in wildlife in Lake Manyara National Park Tanzania. In: Proceedings of the 2nd Tanzania Veterinary Association Scientific Conference held at Arusha International Conference Centre, 4th-6th December 1984. Tanzania Veterinary Association/Sokoine University of Agriculture, Faculty of Veterinary Medicine, Morogoro, Tanzania. 2: pp. 126-139.

Ngatia T A, Kimberling C V, Johnson L W. Whiteman C E and Lauerman L H.1989. Experimental pasteurellosis in goats. Bulletin of Animal Health and Production in Africa 37:13-19.

Nyange J F C. 1984. Animal health trends in northern Tanzania. In: Proceedings of the 11th Scientific Conference held at Arusha, Tanzania, 23-26 October 1984. Tanzania Society of Animal Production, Morogoro, Tanzania. p. 212.

Otaru M M M. 1985. Potential zoonotic diseases in the southern zone of Tanzania. In: Proceedings of the 3rd Tanzania Veterinary Association Scientific Conference held at Arusha International Conference Centre, 3rd-5th December 1985. Tanzania Veterinary Association/Sokoine University of Agriculture, Faculty of Veterinary Medicine, Morogoro, Tanzania. 3: pp. 367-398.

Tekelye Bekele and Kasali O B. 1990. Brucellosis in sheep and goats in central Ethiopia. Bulletin of Animal Health and Production in Africa 38:23-25.

TVA (Tanzania Veterinary Association). 1991. Professional reports. Tanzania Veterinary Association Central Zone Meeting, Singida, October 25 1991. TVA, Morogoro, Tanzania.


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