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Poultry sector growth is being driven by rising incomes, together with the emergence of vertically integrated poultry producers that have reduced consumer prices by lowering production and marketing costs. Integrated production, a market transition from live birds to chilled and frozen products, and policies that help ensure supplies of competitively priced domestic or imported corn and soybeans are keys to future poultry industry growth in developing countries (Maurice et al.,2004)
Poultry industry in Uganda has been fast growing in the recent time implying that there is also more production of poultry products like eggs and meat with about 40% of total rural households keeping chicken or other birds (Byarugaba,2007). With the increase in urbanization, the number of poultry farms is expected to increase as well. The industry has mainly faced a problem of diseases and poor quality feeds that have affected the production of poultry. (Byarugaba, 2007)
The total poultry population in Uganda was projected to be about 32.6 million birds in 2006/7 compared to 23.5 million in 2002. Of this, about 80% comprised of free-range indigenous breeds whilst the remaining 20% is commercial types mainly composed of exotics. Chickens form the main poultry types, but turkeys, ducks, geese, pigeons and ostriches are also kept in some areas. The Eastern Region has the highest numbers of free-range birds (representing about37.3%) followed by the central region. On the other hand, the central region has the highest percentage of exotic poultry numbers (Byarugaba, 2008). Free range poultry keeping is based on local indigenous breeds kept around peasant village households and a few sub-urban homesteads and comprise about 84.2% of the total 23.5 chicken population in the country (Busulwa 2009, Byarugaba, 2009).Traditionally most of the village chicken reared under free range in the homesteads scavenge for food with very little supplementary feeds being provided, most of these birds have high mortality and low growth rates since they are frequently exposed to infections with little quality feeds(Terence et al.,2009). However, some farmers provide supplementary feeds which consist of kitchen left over and cereal grains during harvest; this is done at any time of the day mostly soon after having meals. Water is not provided to chickens because most local farmers are ignorant of its relevance.
Village poultry production systems are based on the scavenging indigenous breeds, chicken being the predominant species in the sector. These local chickens are predominant in villages despite the introduction of exotic and cross breed types because farmers have not been able to afford the high input requirements of the introduced exotic breeds. However, cross breeding of local chickens with exotic chicken breeds has also been taking place and one frequently finds mixed breeds as result of target improvement programmers by different organization such as SARRI chicken breeding project (Sorensen and Ssewanyana, 2003, Byarugaba, 2009).
In the intensive system of poultry production mortality is low as proper disease management is enforced, birds are supplied with commercial formulated feeds and drinking water either using troughs or automatic drinkers. Unlike in the traditional systems where birds may roam around pick up diseases, the main source of disease spread in the intensive system include sharing of farm equipments, movements of personnel from one farm to another, movement of birds from one farm to another, contaminated water and feeds, and poor management practices like failure to follow the vaccination schedules (Kugonza et al., 2008)
However it has been recognized by several stake holders involved in the fight against poverty that chicken rearing is a lucrative source of income, if there is proper disease management to lower mortalities and increase productivity. Disease management is an essential component in the commercial poultry production and if ignored may cause total loss. The poultry industry is not only being affected by diseases and poor quality feeds but also the seasonal availability of day old chicks and the unstable prices of the day old chicks (Kugonza et al., 2008)
1.2 PROBLEM STATEMENT
In Uganda, endemic poultry diseases especially NCD and FOWL TYPHOID present an important limiting factor in the development of commercial poultry production and establishment of trade links.
Many households in Uganda rely on village chickens to supply a significant portion of the dietary proteins in form of eggs and meat especially for women and children. The constant losses from NCD, FOWL TYPHOID and other poultry diseases severely affect the quality and quantity of food for people on marginal diets. The prevalence of poultry diseases varies between the various regions, production systems and time ranges though little data (if any) is available on the trends, and prevalence of NCD and fowl typhoid in the chicken presented for disease diagnosis in the veterinary pathology laboratory.
One of the major constraints of the poultry production in Uganda has been diseases. Among the diseases ranked most rampant and commonly recognized is Newcastle disease (NCD) (Mukiibi-Muka, 1992, Byarugaba, 2007). Other diseases like coccidiosis, fowl typhoid, fowl pox and gumboro (IBD) are also still endemic in Uganda. Knowledge of these disease trends and prevalence help in instituting appropriate control measures and prevent future outbreaks of such diseases with the end result; improved poultry production and household income.
About 40% of the rural households keep chicken or other poultry (Byarugaba, 2007) and also rely on these birds to supply a significant portion of their protein diet especially for women and children. But this is constrained by high effects of poultry diseases especially NCD.
Uganda is a member of the east African free market therefore production of clean healthy and disease free chicks, eggs, and meat for both local and external markets is vital if farmers are to access them. Knowledge of disease trends is vital to control these diseases.
1.4 THE MAIN OBJECTIVE
To determine the trends of NCD & fowl typhoid in chicken presented for post mortem diagnosis at the pathology laboratory of Makerere between 2002 and 2011.
1.5 SPECIFIC OBJECTIVES
The specific objectives are to:
Determine the total number of chicken postmortem cases handled in the pathology laboratory every year since 2002 to 2011.
Determine and compare the prevalence of Newcastle disease and fowl typhoid in each year from 2002 to 2011.
To determine the relationship between Newcastle and Fowl typhoid.
Establish possible solutions to the ongoing Newcastle and fowl typhoid infections, control, management and prevention.
1.6 SCOPE OF STUDY
The study will be carried out at the Veterinary pathology laboratory of Makerere University using postmortem records on the different cases handled since 1972. This assessment will cover all chicken necropsy cases in a period of ten years from 2002 to 2011.
2.0 LITERATURE REVIEW
The most prevalent diseases among poultry include Newcastle disease, respiratory disease complexes, fowl pox, diarrhea, salmonellosis, collibacillosis, fowl cholera, Gumboro, avian leucosis and several parasitic conditions both internal and external. The prevalence of these diseases varies between the different sectors although little data is available. However this largely depends on the preventive measures and management practices in the different sectors. For example in free range there are no vaccinations carried out, Newcastle is the most prevalent causing about 8-100% deaths ( Mukiibi- Muka, 1992, Byarugaba, 2007).
In free range, rearing losses are especially severe due to high mortalities (70%) in chicks up to 8 weeks of age and infectious diseases are reported to be the main cause of death. Knowledge of the epidemiology and management of important diseases in poultry is essential in order to improve the production and, health and is also important in the improvement of the livelihoods of the rural poultry farmers. The resistance and survival of turkeys on Newcastle outbreaks has also been observed although it requires further investigations (Butungi, 2002, Byarugaba, 2007). If the findings are favorable, turkeys may be another poultry species which could be promoted.
The introduction of the privatization of farm input supply of poultry drugs, vitamins, minerals, and vaccines has improved but is still limited to major urban centers. The quality of some of these inputs is of low standard, especially for those that require a cold chain such as vaccines. The cost of input is always high because they packaged in large volumes (such as 1000-5000 dose vaccines) that are not suitable for use by small scale farmers. Another constraint to disease control is that the laboratory diagnostic facilities are not available in up country areas and where they are available, they are expensive. In addition, there are very few extension workers trained and skilled in the diagnosis and treatment of poultry diseases. One of the major constraints of village poultry population in Uganda is generally undoubtedly the existence of various diseases (Ojok, 1993, Byarugaba, 2007).
Among the diseases most commonly recognized is Newcastle disease which has been ranked the most important (Mukibii Muka 1992, Byarugaba 2007)
Most important poultry diseases such as Newcastle, fowl typhoid, pullorum disease, fowl cholera, gumboro, mareks's diseases and fowl pox have all been reported in Africa and are suspected to be responsible for the high rate of mortality observed. Other infections which are known to influence production such as mycoplasma, infectious bronchitis, coryza and parasites are also common. Therefore an adequate disease prevention programme is essential for small holder backyard poultry including sanitation and vaccination. Chronic diseases can reduce efficiency and increase cost of production. Although a disease prevention programme may not show immediate returns on investment, it will be profitable in the long term (Katunguka., 2008).
2.1 SOURCES OF DISEASE
To maintain a flock in an ideal state of health and avoid loss through diseases it is important to have an adequate knowledge of important disease conditions and predisposing factors that influence the spread of disease and resistance of the birds to the disease. The most important predisposing factors are nutritional deficiencies in ration, poor feeding practices, poor ventilation, poor hygiene, overcrowding and environmental stress. A sound knowledge of the mode of spread of poultry diseases is essential for instituting effective preventive measures to break the cycle of infection (Singh., 2008).
2.1.1 Ways of disease spread
Egg transmission (embryonic) certain diseases such as salmonella and E.colli forms may be transmitted from the dam to the off springs through the egg. Other diseases that may be spread in the following way include egg drop syndrome, lymphoid leukosis, pollurum typhoid, synovitis and viral arthritis (Singh., 2008).
Contaminated feeds or water where most important disease in this group is mycotoxicosis due to the formation of toxins in feed stuff mainly corn, as consequence of mould growth. Contamination of water with disease producing agent may occur with fowl cholera and fowl coryza (Singh R.A. 2008).
Humans like visitors, neighbors or farm workers can be major carriers and source of poultry diseases especially employees who work on several farms. Persons who circulate between premises as managers, inspectors, delivery, pick up and visitors may become contaminated with these agents and carry them to other places (Eli Katunguka R, 2008).
Air borne transmissions; respiratory diseases present in the respiratory tract and disease organisms are discharged into the air then other birds become infected by inhaling these agents. Rapid transmissions of respiratory diseases occur among pen mates and across narrow barriers such as feeding allays. Some of these diseases include avian influenza, chronic respiratory disease, infectious bronchitis, mycoplasma synoviae and Newcastle disease. Vector transmission: a vector is anything that serves to carry a disease producing agent from one premise to another. Vectors are of major importance in transmitting respiratory diseases and external parasites such as mites (Singh., 2008).
Hatchery dissemination; aspergillosis (brooder pneumonia) may originate from hatchery contamination with aspergillus fumingatus, the cause of this disease. Aspergillosis may also originate from prolonged storage of bagged feed particularly in himmid climates. Omphalitis or umbilical infection result from poor hatchery sanitation. Staphylococcosis infection is thought to originate, in part from hatcheries (Singh., 2008).
2.3 DISEASE CONTROL
The major management practices that aid in diseases control have been enumerated namely secure replacement stocks only from healthy breeders and use of management practices that prevent disease. Health problems, however, will still occur. In the absence of epidemic situations, these will usually relate to environmental or nutritional causes, the following practices should be observed; Remove and dispose of dead birds promptly, carcasses are carnibalised by other birds and botulism becomes a risk. Control predators to reduce spread of disease and do not allow predators such as dogs and vultures to have accesses to dead birds. Maintain good ventilation as poor ventilation is associated with humid litter and ammonia problems which are detrimental to birds (Singh., 2008).
Maintain a continuing program of cleaning, sanitizing and disinfection. Bird environments team with bacteria and fungi and if an over load is reached problems like collibacilosis and stahlylococcosis may occur. Reduce stress by maintaining temperature control, avoid feed and water interruptions, and excitement, and utilize dim lighting with growing and adult birds. Debeak properly because improper debeaking can be a major cause of unsatisfactory performance in production birds. Adhere to conditions made by supplier of chicks. Do not overcrowd birds and always respect the stocking density and routinely examine a proportion of dead or unthrifty birds for parasites such as lice, mite and ascarids. Some diseases such as Newcastle disease, IBD, fowl typhoid, Mareks disease and many more can be prevented by vaccination (Singh , 2008).
Vaccination is not a good substitute for good health management but it is helpful in controlling certain diseases. Vaccines are also available for infectious bronchitis, fowl pox, epidemic tremors, fowl cholera, laryngotraheitis, erysipelas, coccidiosis and viral hepatitis. Vaccination should only be used in areas where disease is known to exist. Several methods may be used for example individual bird vaccinations by injection, intranasal, intraocular or wing web vaccinations. Flock treatments can also be given in drinking water, by spray or dust (Gillespie, 2002).
2.4 NEWCASTLE DISEASE (NCD)
It is generally considered that the first outbreaks of Newcastle disease occurred in 1926, in Java, Indonesia, and in Newcastle -upon-Tyne, England. There reports of the disease in central Europe similar to what is now recognized as NCD that predate 1926, and Levine, citing Ochi and Hashimoto, indicated that the disease may have been present in Korea as early 1924. Macpherson considered the death of all chickens in western isles of Scotland in 1896 to be attributed to NCD. The name "Newcastle disease" was coined by Doyle as a temporary measure to avoid a descriptive name that might be confused with the other diseases and no better name has evolved since. However in most countries, Uganda inclusive, the history of NCD has not been documented. (Saiif et al., 2003).
The global economic impact of NCD is enormous and is certainly unsurpassed by any other poultry virus, and probably represents a bigger drain in the world's economy than any other animal virus (Dennis. J. Alexander, 2003)
NCD is caused by a virus of avian paramyxovirus serotype 1 (APMV-1) with an incubation period of 2-15 days (average 5-6) after natural exposure (Saiif et al., 2003).
2.4.2 Distribution of NCD and its economic significance
The almost universal use of NCD vaccines in commercial poultry throughout the world makes the assessment of true geographic distribution of NCD difficult. No doubt exists that NCD is either enzootic or a cause of regular epizootics throughout most of Africa, Asia, Central America and parts of South America. In more developed areas, such as Western Europe sporadic epizootics occur on fairly regular basis despite wide spread use of NCD vaccines. The distribution of disease is dependent on the attempts of eradication and control made in individual countries; however, countries with mostly village chicken flocks have far greater problems than those with larger flocks (Saiif et al., 2003).
Village poultry is one of those abundant assets for the rural poor in Uganda that could be utilized to eradicate poverty in the country since poultry farming addresses the needs of the underprivileged in society especially women and children. Newcastle disease has been identified as the principal disease limiting rural poultry production in low-income food-deficit countries (LIFDCs). The disease kills up to 70-100% of household poultry and therefore is a major constrain in village free-range poultry production. It causes heavy losses estimated between US$ 62 million and US$ 78 million per annum in Uganda. (Byarugaba, et al., 2010)
The spread is through movement of live birds (feral birds, pet/exotic birds, game birds, racing pigeons and commercial poultry), contact with other animals, movement of people and equipment, movement of poultry products, inhalation/ air borne spread, ingestion of contaminated poultry feeds and water, and through vaccines (www.worldpoultry.net)
2.4.4 Clinical signs
The speed with which signs appears, if at all, depends on infecting virus strain, host specificity, age of the bird, immunity status, infections with other organisms, route of exposure, dose and environmental conditions. It's a highly infectious disease characterized by coughing, sneezing, rattling and signs of severe respiratory distress. In a small percentage of affected population, nervous symptoms are observed including varying degree of muscular incoordination, muscular tremors, torticollis, paralysis of legs and wings and opithostonos. Other signs include severe respiratory distress, edema around eyes and head and green diarrhea in birds that don't die early in infection. Mortality can be severe depending upon the virulence of a particular strain responsible for the outbreak frequently reaches 100% in flocks of susceptible chickens. It's common to observe 100% cessation of egg production. There are four strains i.e. Beaudette's, Doyle's, Beach's and hitchner's all causing slightly different form of disease (Saiif et al., 2003).
2.4.5 Post mortem lesions
Gross lesions and organs affected in birds affected with NCD are dependent on the strain and pathotype of the infectious virus. In addition the host and other factors (environmental factors) may affect the severity of the disease. Generally no gross lesions are observed in the CNS of birds irrespective of the pathotype. Haemorrhagic lesions are particularly prominent in the mucosa of the proventriculus, caecum and small intestines as a result of necrosis of intestinal wall or lymphoid tissue such as cecal tonsils and payer's patches, egg yolk in the abnormal cavity, hemorrhage and discoloration of the reproductive organs with the ovarian follicles flaccid and degenerative. Small foci of areas of necrosis are seen in liver and, sometimes with haemorrhage in the bladder and heart (www.worldpoultry.net, Saiif Y. M, et al., 2003).
2.4.6 Diagnosis of Newcastle disease
The clinical disease (respiratory and central nervous signs) and gross and microscopic lesions in trachea, nasal trubinates and lungs are helpful in the diagnosis.
Paralysis, incoordination, central nervous signs after first respiratory signs, are diagnostic for NDV. It can be complicated by Mycoplasma or E. coli resulting in CRD and severe air sacculitis. Domestic lento or mesogenic NDV cause mild respiratory disease. Isolate and identify virus from trachea of clinically ill birds in cell culture or chicken embryos for definitive diagnosis. The HI or ELISA test for measuring a rise in antibody titer is helpful. (www.worldpoultry.net)
2.4.7 Treatment and Control of Newcastle disease
Vaccinate by coarse spray or eye drop at one day, or by water or coarse spray at seven days old. In VVND areas, an inactivated vaccine may also be given at 1 and/or 14 days of age. Revaccination by water or spray is done at 14-21 days. Breeders or layers can be vaccinated by water or coarse spray at 6-8 week intervals throughout the growing period in areas with high infection pressure. An inactivated NDV vaccine can be used at around 18 weeks for breeders or layers. Continue live vaccination throughout lay every 6-8 weeks.
In the US the B1 strain is used for the 1st and 2nd vaccination, and lasota or cloned lasota is used thereafter. Outside the US, Hitchner B1 is less used because it gives only limited protection. Instead, primovaccination is given with cloned lasota.
NDV vaccination is usually combined with infectious bronchitis (IB) vaccine. Outside the US, it is preferred to give IB and NCD separate to avoid interference of these vaccines. Only in case of cloned IB vaccine, combinations can be used without loosing effect. Biosecurity is important to control the disease. Imported birds should be subjected to import quarantine regulations. (www.worldpoultry.net)
In many countries, a stamping out policy is used for Newcastle disease. Were it is allowed, emergency vaccination can be carried out in case of acute outbreaks to reduce clinical problems. A broad-spectrum antibiotic can be given to control secondary invaders, especially E. coli from causing CRD (www.worldpoultry.net).
2.5. FOWL TYPHOID
Fowl typhoid is a miscellaneous bacterial disease that attacks the digestive diease(Inetrvet.,2009) . Chicken and turkeys are the most susceptible species but other species of birds can get infected by this disease. Infections are rare mammals and commercially grown game birds such as pheasant, chukar partridge and quail(Butcher et al.,2012). The morbidity and mortality vary with the species and breed, as well as nutrition and management, stress and concurrent infections. Among chickens, lighter breeds such as leghorns are more resistant to the disease than heavier breeds such as Rhode Island Reds, Barred Plymouth Rocks, White Wyandottes or New Hampshires (Anna Rovid Spickler.,2009)
Fowl typhoid is common in some countries of Central and South America, Africa and Asia. This disease has been eradicated from commercial poultry in many developed nations including the U.S., Canada, New Zealand, Australia, Japan and most countries in Europe. In areas where they are absent from commercial chickens and turkeys, Salmonella Gallinarum may still be present in backyard flocks and wild birds. In these areas, fowl typhoid can also occur in intensively reared game birds including pheasants, partridges and guinea fowl.
2.5.2 Economic significance of fowl typhoid
The disease causes a high mortality and morbidity thus leading to vast economic losses both in large scale and small scale poultry producers. The use of S. Pullorum and S. Gallinarum infection models are useful in understanding the avian innate immune system in bacterial infections and increasingly in the actions of the adaptive immune system (Lucy et al.,2009). Salmonella gallinarum is zoonotic (vannesa.,2011).
2.5.3 Aetiology of fowl typhoid
Fowl typhoid results from infection by Salmonella enterica subsp. enterica serovar Gallinarum biovar Gallinarum (Salmonella Gallinarum), a Gram negative bacterial rod in the family Enterobacteriaceae (serogroup D). The iccubation period is 4-6 days. Salmonella spp are facultative intracellular pathogens causing localised or systemic infections, in addition to a chronic asymptomatic carrier state (Zhang et al 1999).
Horizontal and vertical transmissions are both important in the epidemiology of fowl typhoid. Birds can become chronic carriers for Salmonella gallinarum, passing them to their offspring in eggs. Horizontal transmission occurs via the respiratory and oral routes. Birds can ingest bacteria after environmental contamination or during cannibalism. Wound infections are also possible. Salmonella gallinarum can be transmitted on fomites including contaminated feed, water and litter; they may survive in a favorable environment for many months and up to several years. Wild birds, mammals, and insects can act as mechanical or biological vectors. Red mites may be involved in the transmission of disease and persistence in poultry house. The transmission can thus occurs through bird-to-bird contact, hen to egg to chick (recovered hens will pass on the disease to roughly 1/3 of her eggs), chick to chick, cannibalism of infected carcasses, wound contamination, fecal contamination of feed, water and litter, contaminated incubaters, chick boxandhouses(Butcher et al.,2012). However, wild birds, mammals and flies are also capable of spreading the disease.
2.5.6 Clinical signs of fowl typhoid
When hatched from infected eggs, chicks and poults begin to sicken and die soon after hatching. Birds develop nonspecific signs such as depression, weakness, somnolence, loss of appetite, drooping wings, huddling, dehydration and ruffled feathers. Labored breathing or gasping as well as diarrhea and pasting of the vent feathers (butcher et al.,2012). They make shrill chirping and peeping sounds while attempting to eliminate chalky white and viscous droppings from their vents. In some cases signs do not appear for 5 to 10 days after hatching, but then will increase for 7 -10 days, with most deaths occurring by the second to third week of life. Blindness, lameness and (or)joint swelling may be apparent in some what older birds. The clinical signs in growing and older irds may include; high mortality and morbidity decreased appetite, depression, dehydration, weight loss, ruffled feathers, and watery to mucoid diarrhea. A progressive loss of condition can lead to anemia with pale, shrunken combs(intervet.,2009). Occasionally, Salmonella Pullorum may cause a disease similar to fowl typhoid in older birds; the most common signs are anorexia, depression, diarrhea and dehydration. Salmonella Gallinarum can cause decreased egg production, fertility or hatchability in inapparent carriers as well as in birds with systemic signs.
2.5.7 Diagnosis of fowl typhoid
Clinical signs, flock history, mortality and post-mortem lesions can be suggestive, but may resemble septicemia caused by other agents. Laboratory confirmation is essential. Analytical Profile Index (API) system can be used for identification, Polymerase chain reaction (PCR) assays can be used to identify Salmonella Gallinarum
2.5.8 Treatment and Control of fowl typhoid
Serological tests are satisfactory for identifying the presence and estimating the prevalence of infection within a flock where slaughter can be used to effectively eliminate salmonella gallinarum(Lax et al.,1995). Vaccination e.g use of cpxR (Kiku et al 2011, Zhang et al.,1999, Rafael et al 2010). Chemotherapeutic agents such as sulfonamides, antibiotics, and antibacterials are effective in reducing mortality(Butcher et al.,2012).In local free scavaging poultry,aloe (A. secundiflora _ar. Secundiflora)extract can be used ( Waihenya et al., 2001).
3.0 Materials and methods
3.1 Research design
This research will be a retrospective study involving the examination and tallying of necropsy cases and the reports of diagnosis of Newcastle and Fowl typhoid in the last ten years (2002-2011). The total number of chicken presented to the pathology laboratory for necropsy diagnosis for each year will be computed from the available records and prevalence of NCD and fowl typhoid calculated for each year in the last ten years. The trends of diseases will be compared in the ten years period.
3.2 Sample size determination
This will be purposive sampling where all records of chicken presented for necropsy between the years 2002 to 2011 will be considered.
3.3 Data collections
The information from the necropsy records will be arranged and inserted in a data collection form according to its corresponding date of post mortem and diagnosis. The data collection form will have provisions for the total number of chicken post mortem cases diagnosed with fowl typhoid and new castle disease per month in each of the years (2002-2011).
Data collection card
3.4 Data analysis
The data collected will be analysed using descriptive statistics, the tallied results in the data collection form will then entered in a Microsoft excel spread sheet to generate tables and graphs. These will then show disease frequencies, trends and proportions in each year and over the past decade.The annual frequencies will then be analysed using correlation method to determine the relationshipbetween NCD and Fowl typhoid.
Table 6: weekly data collection sheet
Data summary card