Livestock Research for Rural Development 25 (11) 2013 Guide for preparation of papers LRRD Newsletter

Citation of this paper

An investigation of the common causes of death in chicken around Arusha Municipality area, Tanzania

E S Swai, P N Sanka* and J E Kaaya*

Ministry of Livestock and Fisheries Development, PO Box 9152, Dar-es-Salaam, Tanzania
* Veterinary Investigation Centre, PO Box 1068 Arusha, Tanzania


A retrospective study covering a period of 5 years (1998-2002) was carried out using post mortem records at the zonal veterinary investigation centre laboratory to determine the major and probable causes of poultry deaths in and around Arusha Municipality. During this period, a total of 2216 avian commercial (broiler & layer) poultry carcasses of different ages and from different sources were examined and 2027 (91.5%) died as a result of a variety of causes.

No cause of death could be identified from 189(8.5%) cases. Protozoan disease problem namely coccidiosis (1016) was the most important cause of deaths (45.5%). The other problems occurred in the following frequencies; Management related problems 16.3%; Viral diseases 12.5%; Helminthiasis 6.8%; Bacterial diseases 4.5. % and Egg bound peritonitis 5.5%. No seasonality pattern of the diseases could be elucidated, however, it was concluded that coccidiosis, and management related diseases and viral diseases namely Infectious Bursal Disease (IBD) were the most important disease of commercial chicken in the area of study. The recurrence of these diseases perhaps suggests the level of their endemicity and highlights the need for sustained surveillance and intensive control measures.

Key words: Arusha, poultry diseases, Tanzania


The main objective of chicken industry is to produce meat and eggs efficiently and economically (Melewas and Rwezaula 1988; Whyte 2002; URT 2006; 2010; Rushton 2009). Several factors either acting singly or in combination may hamper chicken production (Minga and Nkini 1989; Jordan and Pattison 1996, Calnek et al 1997; Sonaiya and Swan 2004).

Besides poor feeding, housing and management, diseases are one of the most important constraints to poultry industry worldwide (Minga et al 1996; Yongolo et al 2011; Knueppel et al 2010; Msoffe et al 2010). Diseases reduce chicken production by reducing productivity and causing economic losses as a result of sub-optimal productivity, high veterinary expense, culling as well as actual chicken mortality. Broadly, continued persistency of diseases exert severe impacts on food security, nutrition, health and financial costs at various level from producer, local, regional and national economy.

The continued surveillance of the major diseases of poultry and those which might have hitherto been considered to cause significant morbidity and mortality is desirable.

The purpose of this paper is to review the various causes of avian (poultry) mortality as diagnosed at the post mortem facility in the Veterinary Investigation Centre, Arusha, during a five year period (1998 to 2002).

Materials and Methods

Area and coverage

This study was conducted at Arusha zonal Veterinary Investigation Centre (AZVIC), which is located within Arusha Municipality, the second largest municipality in Tanzania. Geographically, the municipality is situated at the foot of Mount Meru (Lat 03’16S and 03’20S and Longt 36’37 and 36’50 E) and intersect the Great North Road from Cape Town to Cairo and is the hub of the northern tourist circuit of Tanzania. Currently the human population is estimated at 1,288,008 with a growth rate of 3.2% as opposed to the national of 2.8% per annum (URT 2002). AZVIC support and undertake animal disease surveillance and laboratory services covering four administrative regions (comprising 27 local administrative authorities/districts) of northern Tanzania. The area elevation ranges from 1200-1900 metres above sea level, average bimodal rainfall ranges from 700 to 2000 millimetres and diurnal temperature range of 15 to 32C (Mhita and Venalinen 1992). Poultry keeping is widely practiced in most urban and peri-ubarn of Arusha municipality and other adjacent districts main towns.

Source and retrieval of post mortem data

Carcases or live sick birds submitted to the AZVIC-laboratory section that originated from different farm sources mainly Arusha Municipality and occasionally from other neighbouring local government authorities (Meru, Monduli, Hai, Moshi and Karatu) were used for the study. A five-year post mortem record (January 1998 - December 2002) of the AZVIC was utilised for this study. Post mortem data recorded in the study period were extracted from case files/registers and post-mortem reports. The diagnosis were based mainly on the gross pathological changes and in some cases, however, few, on microbiological findings. In cases where the pathological changes were found to affect more than one system or organ, only the primary pathological changes have been considered in this report. Other data extracted include data on season of carcase submission, year and classes (broiler or layers). The following season were considered: Dry season (January to March), Wet season (April to June), Pre-wet season (July-September) and Pre-dry season (October to December). Descriptive statistics and graphical illustration was generated in Micro Soft Excel (Microsoft Inc., USA). For description purposes, diseases were categorized into bacterial, viral, coccidiosis, helminthiasis, management related and egg bound peritonitis based on history and gross post mortem lesions.


A total of 2,216 cases of poultry deaths were submitted and recorded during the five year period of the study, giving an average of about 443.2 cases annually (Table 1). On yearly distribution, highest submission of cases was observed in 1998 (24.6%), followed by 1999 with (19.8%) and the least of (18.3%) was recorded in 2000 and 2002, respectively (Table. 1). Of the examined chicken, 189(8.5%) no diagnosis could be made. Two thousands and twenty seven of 2216(91.5%) chicken were affected by one or more of the disease condition described below (Table 1).

Table 1. Some common causes of poultry deaths as diagnosed at post mortem around ZVIC area, Arusha, Tanzania
Disease or condition Annual distribution of cases
1998 1999 2000 2001 2002 Total, %
Coccidiosis 214 230 197 184 191 1016 (45.8)
Management related 88 77 65 69 64 363 (16.3)
Inconclusive 75 32 35 23 24 189 (8.5)
Helminthiasis 21 28 21 40 41 151 (6.8)
Viral 84 46 53 41 52 276 (12.4)
Bacterial 36 17 10 25 11 99 (4.4)
Egg bound peritonitis 29 9 26 34 24 122 (5.5)
Total, % 547(24.6) 439(19.8) 407(18.3) 416(18.7) 407(18.3) 2216

One thousands and sixteen (45.6%) were considered to have died due to protozoan Eimeria spp parasite infection. The condition was reported in all months and years under review except during the month of February 1998 and 2001, respectively.

Management complex

Management related disease condition affected 363 of 2216(16.3%) cases. Of these, chilling accounted for 218(60%) cases. Chilling was more common observed in rain season (April–June). Other conditions were distributed as follows: vitamin deficiency, 63 of 363(17.3%), starvation, 36 of 363 (9.9%), cannibalism, 24 of 363 (6.6%) and injuries due to various cause 22 of 363(6.0%).

Viral diseases

Viral disease was encountered in 276 of 2216(12.4%) cases. Of the viral disease, Infectious bursa disease (IBD) was encountered in higher frequency 175 of 276(63.4%) followed by New castle disease (NCD) 63 of 276(22.8%) and visceral lymphomatosis, 38 of 276(13.7%).

Bacterial diseases

Ninety nine of 2216 (4.4%) chicken were diagnosed as having died of bacterial associated infections. These were distributed as follows: Omphalitis, 26 of 99 (26.2%), Collibacillosis, 21 of 99 (21.2%), Salmonellosis, 18 of 99 (18.1%), Pasterellosis, 18 of 99 (18.1%) and infectious coryza, 16 of 99(16.6%).


One hundred and fifty one of 2216(6.8%) were emaciated and massively associated with both endo- and ectoparasites. Five chicken of 151(3%) had severe lice and flea infestation. Of the endo-parasites, 122 of 146(83.5%) were roundworm namely, Ascaridia and Hetarakis spp and 23 of 146(15.7%) was tapeworm, Taenia spp.

Figure 1. Seasonal distribution of reported chicken carcasses during 1998-2002


The results show that the number of cases received each year decreased by 25% in the last year of consideration. The reason for this decrease in the number of cases can possibly be attributed to the post mortem cost recovering exercise which was introduced since 1998 or the re-surgence of private veterinary delivery centres in the light of liberalised veterinary service delivery (Melewas and Rwezaula 1988) or that the owners were no longer interested in their chicken being examined at post-mortem.

The second and third most frequent group of diseases were those associated with management (chilling, nutrition, cannibalism, mechanical injuries etc) and viral (IBD, New Castle Disease, Visceral lymphomatosis) infection. These accounted for 16.3% and 12.4% respectively, of all deaths. This means that less than 30% deaths were attributed by various other causes as listed in Table 1. No firm evidence of seasonality pattern could have been elucidated from the death trends noted over years under review, suggesting disease challenge in the area have no seasonality trend.

Conflict of interest statement

None of the authors of this paper has a financial or personal relationship with other people or organization that could inappropriately influence or bias the content of the paper.


The authors are very grateful to the AZVIC technical staff that performed the post mortem, keep the records and for their cooperation and help. This paper is published with the permission from the Director of veterinary services in Tanzania.


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Received 30 August 2013; Accepted 10 October 2013; Published 1 November 2013

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