Retrospective Study of Some Viral Poultry Diseases Diagnosed in Nigeria

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1 International Journal of Basic and Applied Virology 3(1): 16-21, 2014 ISSN IDOSI Publications, 2014 DOI: /idosi.ijbav Retrospective Study of Some Viral Poultry Diseases Diagnosed in Nigeria A.M. Wakawa, M.I. Waziri, H.B. Aliyu, A.M. Talba, L. Sa idu and P.A. Abdu 1 Avian Medicine Unit, Department of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria 2 Avian Clinic, Veterinary Teaching Hospital, Ahmadu Bello University, Zaria, Nigeria Abstract: A ten year ( ) retrospective study of the prevalence of Newcastle disease (ND), Avian influenza (AI), Infectious bursal disease (IBD) and Marek s disease (MD) diagnosed at the Poultry Clinic of Ahmadu Bello University Veterinary Teaching Hospital, Zaria, Nigeria, was conducted. The specific rates (SR) of the aforementioned viral diseases were determined based on year, month, season, species, age and vaccination history. An overall prevalence of 46.6% (1, 391 cases) for the four viral diseases out of 2, 983 cases of poultry diseases was determined. Prevalence of 29.1%, 1.1%, 8.9% and 7.5% were recorded for ND, AI, IBD and MD, respectively. The highest SR for ND (42.4%) was observed during the dry season. AI outbreaks were recorded only in 2006, 2007 and 2008 with the highest SR (6.6%) in Although, IBD occurred throughout the year, the highest SR (14.9%) was in June (pre-rainy season). A yearly increase in SR for MD was observed, with the highest (11.0%) being in Only chickens suffered from all the four viral diseases with SRs of 29.9%, 0.9%, 10.7% and 8.8% for ND, AI, IBD and MD, respectively. Based on age, the highest SR for ND was observed in chicks 0-8 weeks old (32.2%), for AI in adults above 20 weeks (2.1%), for IBD in chicks 0-8 weeks (15.0%) and for MD in growers 9-20 weeks (15.1%). While ND and IBD remained endemic, MD is increasingly becoming a major problem to poultry farmers in Zaria, Nigeria. There is a need to investigate the ND, IBD and MD virus strains currently in circulation with a view to developing appropriate vaccines against them. Even though, AI cases are no longer reported in Nigeria, the continued surveillance for the virus was also recommended. Key words: Newcastle Disease Avian Influenza Infectious Bursal Disease Marek s Disease Zaria Nigeria INTRODUCTION Some of the commonest viral poultry diseases reported to be endemic and vaccinable in Nigeria are Newcastle disease (ND), Infectious bursal disease (IBD) and Marek s disease (MD) [1, 2]. Outbreaks of ND, AI and IBD were first reported in Nigeria in 1952, 2006 and 1973, respectively [3-5]. There is paucity of information on the first reported case of MD in Nigeria, but diagnostic studies conducted between 1975 and 1984 reported a total of 22 cases of MD [6]. However, Avian influenza (AI) is not endemic, but outbreaks have occurred in 2006, 2007 and 2008 [4, 7]. All the aforementioned viral diseases have caused heavy economic losses to the poultry industry in Nigeria [8-10]. Except AI, the other viral diseases are still causing economic losses to farmers in developing countries including Nigeria [2, 11]. In view of the fact that emphasis of veterinary medicine has been on treatment of diseases and only a little attention is focused on herd health and preventive medicine [11], there is a need to conduct this study in order to further elucidate the epidemiology of ND, AI, IBD and MD affecting poultry. This may stimulate the interest and awareness of policy makers for the need to prevent and control these diseases which have been causing heavy economic losses to Nigerian poultry farmers. MATERIALS AND METHODS Study Area: All the cases studied were presented in Zaria, a city located between N and 7 44 E within the Sudan savannah zone in Northern Nigeria. The dominant Corresponding Author: A.M. Wakawa, Avian Medicine Unit, Department of Veterinary Medicine, Ahmadu Bello University, Zaria, Nigeria. Tel:

2 vegetation is grasses and trees. The average rainfall Statistical Analysis: The data were reduced to tables with ranges from mm and average daily respect to frequency of ND, AI, IBD and MD cases temperature ranges from C [1]. according to year, month, season, species, age and vaccination history. The specific rates (prevalence) for Data Collection: The 10 years records, January 2003 to each disease based on year, month, season, species, age December 2012, of cases diagnosed based on history, and vaccination history were determined [12]. clinical signs, post mortem findings, histopathological findings and agar gel immunodifusion test, at the Poultry RESULTS Clinic of Ahmadu Bello University Veterinary Teaching Hospital (ABUVTH), Zaria, Nigeria. The case records were During the period under review, a total of 2, 983 cases subjected to a retrospective analysis. The year, month, of poultry diseases were diagnosed based on the species, age and vaccination history on Newcastle aforementioned methods, out of which ND, AI, IBD and disease, Avian influenza, Infectious bursal disease and MD accounted for 1, 391 (46.6%). The prevalence of ND, Marek s disease diagnosed were extracted from the clinic AI, IBD and MD were 29.1%, 1.1%, 8.9% and 7.5%, case record books. A case was defined as a farm that respectively. A yearly increase in SR for MD was reported an outbreak of a disease and diagnosed based observed, with the highest being in 2011 (Table 1). on history, clinical findings, serology, postmortem The highest SR for ND were during the months of findings and histopathological findings. November (44.4%), December (46.9%), January (44.1%) and February (47.8%). While highest SRs for IBD and MD Data Management: Information on ND, AI, IBD and MD were in May (14.9%) and June (14.5%), respectively cases were extracted from the record. The age of the birds (Table 2). The seasonal distribution showed that the were categorized in weeks; 0-8 (chicks), 9-20 (growers) highest SRs for ND (42.4%) and AI (5.3%) occurred and above 20 weeks (layers). According to species, the during the dry season, while for IBD (11.9%) and MD birds were categorized as chickens, turkeys, parrots, (10.0%) were in the pre-rainy season (Table 2). Only pigeons, geese, ducks and ostriches. The seasons in chickens suffered from all the four viral diseases with SRs Zaria were categorized as dry season (January to March), of 29.9%, 0.9%, 10.7% and 8.8% for ND, AI, IBD and MD, pre-rainy season (April to June), rainy season (July to respectively (Table 4). Based on age, the highest SR for September) and pre-dry season (October to December) [1]. ND was observed in chicks 0-8 weeks old (32.2%), for AI Table 1: Yearly distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) ND cases AI case IBD cases MD cases Year (Non ND) (Non AI) (Non IBD) (Non-MD) Total no. of all cases 2003 Cases: 89 (200) 0 (289) 19 (270) 9 (280) 289 SR (%) Cases: 83 (161) 0 (244) 21 (223) 12 (232) 244 SR (%) Cases: 97 (209) 0 (306) 31 (295) 19 (287) 306 SR (%): Cases: 89 (199) 19 (269) 39 (271) 18 (270) 288 SR (%): Cases: 92 (235) 13 (314) 25 (312) 26 (301) 327 SR (%): Cases: 85 (233) 2 (316) 33 (285) 29 (289) 318 SR (%): Cases: 69 (214) 0 (283) 31 (262) 22 (261) 283 SR (%): Cases: 91 (228) 0 (319) 47 (300) 31 (288) 319 SR (%): Cases: 89 (219) 0 (308) 27 (291) 34 (274) 308 SR (%): Cases: 83 (218) 0 (310) 13 (288) 23 (278) 301 SR (%): Total 867 (29.1) 34 (1.1) 267 (8.9) 223 (7.5) 2, 983 ND: Newcastle disease, AI: Avian influenza, IBD: Infectious bursal disease, MD: Marek s disease, SR: Specific rate 17

3 Table 2: Monthly distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) ND cases AI cases IBD cases MD cases Month (Non-ND) (Non-AI) (Non-IBD) Non-MD) Total no. of all cases January Cases: 101 (128) 15 (214) 7 (222) 11 (218) 229 SR (%): February Cases: 95 (104) 17 (182) 10 (189) 14 (185) 199 SR (%): March Cases: 72 (129) 1 (200) 7 (194) 12 (189) 201 SR (%): April Cases: 53 (195) 1 (247) 18 (230) 12 (236) 248 SR (%): May Cases: 56 (259) 0 (315) 47 (268) 32 (283) 315 SR (%): June Cases: 47 (236) 0 (283) 36 (247) 41 (242) 283 SR (%): July Cases: 68 (235) 0 (303) 15 (288) 33 (270) 303 SR (%): August Cases: 46 (251) 0 (297) 9 (288) 17 (280) 297 SR (%): September Cases: 63 (183) 0 (246) 10 (236) 12 (234) 246 SR (%): October Cases: 72 (170) 0 (242) 9 (233) 14 (228) 242 SR (%): November Cases: 88 (106) 0 (194) 7 (187) 9 (185) 194 SR (%): December Cases: 106 (120) 0 (226) 11 (215) 16 (210) 226 SR (%): Total 867 (29.1) 34 (1.1) 267 (8.9) 223 (7.5) 2, 983 Table 3: Seasonal distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) ND AI IBD MD Season (Non ND) (Non AI) (Non IBD) (Non MD) Total no. of all cases Dry Cases: 267 (362) 33 (596) 24 (605) 37 (592) 629 (Jan-Mar) SR (%): Pre-rainy (Apr-June) Cases: 166 (680) 1 (845) 101 (745) 85 (761) 846 SR (%): Rainy Cases: 168 (678) 0 (846) 34 (812) 62 (784) 846 (Jul-Sep) SR (%): Pre-dry (Oct-Dec) Cases: 266 (396) 0 (662) 27 (635) 39 (623) 662 SR (%): Total 867 (29.1) 34 (1.1) 267 (8.9) 223 (7.5) 2, 983 Table 4: Species distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) Season ND (Non-ND) AI IBD MD Total no. of all cases Chickens Cases: 748 (1,951) 23 (2, 473) 267 (2, 232) 221 (2, 278) 2, 499 SR (%): Turkeys Cases: 91 (247) 4 (339) 0 2 (341) 343 SR (%) Ducks Cases: 0 3 (67) SR (%): Geese Cases: 0 2 (30) SR (%): Pigeons Cases: 23 (0) SR (%): Parrots Cases: 2 (5) SR (%): Ostriches Cases: 3 (6) 2 (7) SR (%): Total 867 (29.1) 34 (1.1) 267 (10.0) 223 (7.5) 2,

4 Table 5: Age distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) ND AI IBD MD Age (weeks) (Non-ND) (Non-AI) (Non-IBD) (Non-MD) Total no. of all cases 0-8 Cases: 384 (807) 4 (1,187) 179 (1,012) 97 (1,094) 1, 191 (chicks) SR (%): Sep Cases: 192 (605) 9 (788) 6 (791) 120 (677) 797 (growers) SR (%): Above 20 Cases: 291 (704) 21 (974) 1 (994) 6 (985) 995 (adults) SR (%): Total 867 (29.1) 34 (1.1) 186 (6.2) 223 (7.5) 2, 983 Table 6: Distribution of some viral poultry diseases diagnosed at ABUVTH, Zaria, Nigeria ( ) based on vaccination history ND AI IBD MD Total no. of all cases Season (Non-ND) (Non-AI) (Non-IBD) (Non-MD) Vaccinated Cases: 139 (555) 0 (0) 38 (656) 46 (648) 694 SR (%) 20 0 (0) Not vaccinated Cases: 728 (1, 561) 34 (2,255) 148 (2, 141) 177 (2, 112) 2, 289 SR (%): Total 867 (29.1) 34 (1.1) 186 (6.2) 223 (7.5) 2, 983 ND: Newcastle disease, AI: Avian influenza, IBD: Infectious bursal disease, MD: Marek s disease, AP: Avian pox, SR: Specific rate, OR: Odds ratio at 95% confidence interval in adults above 20 weeks (2.1%), for IBD in chicks 0-8 in Nigeria in July, 2008 [9]. The outbreaks of AI in the weeks (15.0%) and for MD in growers 9-20 weeks (15.1%) aforementioned years have affected 3, 057 farmers; about (Table 5). Based on vaccination history, the highest SRs 1.3 million of the country s 160 million birds were were observed in unvaccinated birds for all the four viral destroyed and the Nigerian government had to pay N900 diseases which include ND (31.4%), AI (1.5%), IBD (6.5%) million (US$5.4) in compensation to farmers [9, 10]. It may and MD (7.7%) (Table 6). be logical to say that the sudden disappearance of AI since 2008 to date, despite on-going surveillance efforts, DISCUSSION may be attributed to the stamping out policy adopted by Nigeria in controlling outbreaks, coupled with the The study confirmed that ND was the most common rigorous campaign against the disease embarked upon by viral disease of chickens in Zaria. ND was found to be the country and other international organizations since more prevalent during the months of November, Most of the birds affected by AI during the period December, January and February. These months under study were adults (above 20 weeks). This may be coincided with harmattan period which is usually cold, attributed to the fact that during the period of the dusty and windy in Northern Nigeria. It was suggested outbreaks, most of the affected farms in all the affected that the high wind velocity and the amount of dust in the States had birds that were at point-of-lay or already air may influence the transmission and spread of the laying; since most farms do not stock birds during the disease and the extreme cold may also exacerbate the cold harmattan period (December-February) because outcome of the disease [11, 12]. ND was not reported in brooding is difficult and expensive during this period [10]. Geese and ducks probably due to the assertion that they AI outbreaks were not reported in vaccinated birds are usually considered resistant even to strains of probably because the use of AI vaccine in poultry is Newcastle disease virus most virulent for chickens, illegal. Although, geese and ducks were reported to be although outbreaks of disease in ducks associated with fairly resistant to AI, in this study, the specific rates ND virus infection have been described [13]. Based on observed for geese and ducks were even higher than age distribution of ND, the finding also supported those of chickens, turkeys and ostriches. previous reports that most species of bird that are young Even though, IBD occurred throughout the period are more susceptible than the adult [14, 15]. under review and throughout the year, the highest It is important to note that the first case of AI on the specific rates were observed in May and June (pre-rainy African continent was reported in Nigeria in January, season). In Zaria and environs, it is a common practice to AI (HPAI to be specific) cases were subsequently restock between March and May, probably because of reported in 2007 and The disease was last reported ease of brooding in terms of financial input [1]. However, 19

5 if the chicks become exposed to IBD virus during this CONCLUSION AND RECOMMENDATIONS time, the disease may manifest clinically. This may explain for the high specific rates recorded during this ND and IBD remained endemic, while MD is time. The finding that IBD was most prevalent in chicks increasingly becoming a major problem to poultry farmers may be attributed to the apparent susceptibility of the in Zaria, Nigeria unlike in the past 2 decades. There is a chicks from 3-5 weeks of age when the MDA is need to investigate the ND, IBD and MD virus strains decreasing. It has been reported that the bursa of currently in circulation in the field, with a view to Fabricius, the target organ reaches its maximum developing appropriate vaccines against them. Even development between 3 and 6 weeks after hatch rendering though, AI cases are longer reported in Nigeria, the the chicks highly susceptible to the IBDV [16]. Although, continued surveillance for AI virus as part of an early it is expected that unvaccinated chicks should have warning system is also recommended. higher specific rates, the outbreaks in vaccinated chicks recorded should not be overlooked. The occurrence of ACKNOWLEDGEMENT IBD in the vaccinated flocks could either be due to vaccine failure, non-maintenance of cold chain, improper The authors are grateful to the technical staff of handling of vaccine or low level of maternal antibodies Poultry Clinic, ABUVTH and Serology Laboratory, and increasing virulence of field IBD virus strains [17]. Department of Veterinary Medicine, Ahmadu Bello It may also be attributed to the different vaccination University, Zaria, Nigeria. schedules being recommended by commercial hatcheries, veterinary practitioners and other animal health workers REFERENCES in practice to farmers in Nigeria, irrespective of the level of maternal antibodies in the chicks [18]. 1. Sa idu, L., P.A. Abdu, J.U. Umoh and S.U. Abdullahi, The prevalence of MD also indicates that the disease Diseases of Nigerian indigenous chickens. is increasing becoming one of the most economically Bulletin of Animal Health and Production in Africa, important viral diseases in Nigeria. The yearly increase in 42: SR of MD observed over the past 10 years may be 2. Abdu, P.A., Viral diseases. In: Manual of attributed to a number of reasons: non vaccination of nd Important Poultry Diseases in Nigeria. 2 ed. Zaria. chicks after hatching at hatcheries, cases of vaccine MacChin Multimedia Designer, pp: failures and different field strains of MD viruses possibly 3. Ezeokoli, C.D., J.U. Umoh, A.A. Adesiyun and in circulation which antibodies are not recognizing P.A. Abdu, Prevalence of Newcastle [19, 20]. In Nigeria, the fact that MD vaccines are not disease virus antibodies in local and exotic chicken locally produced has resulted in the introduction of under different management systems in Nigeria. MD vaccines from different countries into the country. Bulletin of Animal Health and Production in Africa, This may presents risks for MD infection among poultry 32: flocks in the country and also evolution of MD variants 4. Adene, D.F., A.M. Wakawa, P.A. Abdu, which may be considered as the likely causes of MD L.H. Lombin, H.M. Kazeem, L. Sa idu, M.Y. Fatihu, outbreaks even in vaccinated flocks, as has been reported T.M. Joannis, C.A.O. Adeyefa and T.U. Obi, elsewhere. The finding that chickens suffer more from MD Clinico-pathological and husbandry features is consistent with previous reports that chickens are by associated with the maiden diagnosis of avian far the primary hosts of the virus, although turkeys are influenza in Nigeria. Nigerian Veterinary Journal, rarely affected [21]. Growers between 9 to 20 weeks of age 1: suffered more from MD. It is important to note that more 5. Okoye, J.O.A. and M. Uzoukwu, Mareks cases manifested between 9 and 20 weeks of age, Histopathogenesis of local Nigerian isolates of but can appear even later if the bird had 'latent' MD and is infectious bursal disease virus in broilers. In the substantially stressed. Most cases in this study were Proceedings of 2001 International Symposium on IBD seen in growers because they had the classical form of the and CIA, Germany, pp: disease which is a chronic form and this agrees with a 6. Fatumbi, O.O. and D.F. Adene, A ten year previous report [22]. When they are exposed to early prevalence study of Marek s disease and Avian infection, by the time the clinical signs manifest, the birds leokosis at Ibadan, Nigeria. Acta Veterinaria Brno., must have developed to the grower stage [18, 20]. 55:

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