The prevalence and economic significance of Fasciola gigantica and Stilesia hepatica in slaughtered animals in the semi-arid coastal Kenya

Trop Anim Health Prod (2006) 38:475 483 DOI 10.1007/s11250-006-4394-4 ORIGINAL ARTICLE The prevalence and economic significance of Fasciola gigantica and Stilesia hepatica in slaughtered animals in the semi-arid coastal Kenya E. O. Mungube S. M. Bauni B.-A. Tenhagen L. W. Wamae J. M. Nginyi J. M. Mugambi Accepted: 3 April 2006 C Science + Business Media B.V. 2006 Abstract Fasciola gigantica and Stilesia hepatica constrain ruminant productivity. The prevalence and economic losses caused by F. gigantica and S. hepatica in the ruminant production systems of Taveta division of Kenya were estimated in a retrospective appraisal of the slaughter records on the total number of animals slaughtered and livers condemned over the period 1989 to 2004. Only liver condemnations based on infestation by F. gigantica and S. hepatica were considered for purposes of this study. Liver condemnation rates differed significantly between bovines, caprines and ovines (p 0.05) for F. gigantica (26%, 6.6% and 5.2%, respectively) and for S. hepatica (0.4%, 22% and 28%, respectively). The total loss through condemnation of both F. gigantica and S. hepatica infested livers E. O. Mungube ( ) S. M. Bauni Kenya Agricultural Research Institute, Katumani Research Centre, PO Box 340-90100, Machakos e-mail: wamateka@hotmail.com B.-A. Tenhagen Freie Universität Berlin, Fachbereich Veterinärmedizin, Tierklinik für Fortpflanzung, AG Bestandsbetreuung and Qualitätsmanagement, Königsweg 65, D-14163 Berlin, Germany L. W. Wamae Kenya Agricultural Research Institute, Headquarters, PO Box 57811-00200, Nairobi J. M. Nginyi J. M. Mugambi Kenya Agricultural Research Institute, Veterinary Research Centre, PO Box 32-00902, Kikuyu, Kenya was 4 408 272 KES (Kenyan shillings) (US$ 72 272). The proportion of loss in bovines, caprines and ovines, was 76%, 17% and 7%, respectively. Fasciolosis contributed 3 505 410 KES (79.5%) and S. hepatica infestation 903 210 KES (20.5%) to the total losses due to liver condemnations. The authors feel strongly that there is a need for more work on the two parasites using live animals to determine the prevalence in animals of various ages, species and breeds and the economics of disease control at farm level. Keywords Cattle. Goats. Sheep. Fasciolosis. Stilesia liver. Abattoir survey Abbreviations Cl confidence interval GDP gross domestic product KES Kenyan shilling MoL&FD Ministry of Livestock and Fisheries Development Introduction Fasciolosis, a disease caused by Fasciola gigantica, has been reported as a major constraint to ruminant production in the coastal region of Kenya (MoL&FD, 2004). The disease causes very high mortalities, especially in small ruminants and calves (Cheruiyot, 1987; Hammond and Sewell, 1990; Wamae and Cheruiyot, 1990; MoL&FD, 2004). Other losses associated with

476 Trop Anim Health Prod (2006) 38:475 483 fasciolosis include total condemnation of infected livers or partial condemnation through trimming of affected parts of the liver, which reduces the volume of liver sold. These losses are considerable, although they vary from one part of the country to another depending on fasciolosis pressure, which is dependent on prevailing climatic conditions. Few studies have attempted to estimate the annual fasciolosis slaughter loss through liver condemnations in Kenya. The annual national loss has been estimated at between approximately 0.15 0.26 million USD (Castelino and Preston, 1979; Cheruiyot, 1983; Anon, 1986; Wamae et al., 1998; Kithuka et al., 2002). However, omissions have been noted from meat inspection records in the event of liver trimmings due to light infection which are never considered when condemnation records are kept (Cheruiyot, 1987). Light infections are sometimes disregarded on meat inspection (subjectivity of inspectors). There are other indirect losses, e.g. lowered weight gains poor feed utilization and poor quality of meat and milk products, some of which are hard to quantify. Stilesia hepatica is a tapeworm whose epidemiology is poorly understood. It is also a major cause of concern in the trade of small ruminants and camels but rarely cattle (Nginyi et al., 1993; Gallivan et al., 1996; Bekele, 2002). Wild animals are the natural reservoirs of this parasite and play an important role in its epidemiology (Gallivan et al., 1996). The parasite has a predilection for the bile ducts and causes no pathogenesis but it is a cosmetic problem that leads to liver condemnations at slaughter of the affected animals (Hansen and Perry, 1994). There is very little information on the economic losses attributed to this parasite. Slaughter surveys have been widely conducted in most sub-sahara African countries, including Kenya, to estimate prevalence and the economic significance of fasciolosis in various ruminant production systems. Unfortunately, the impact of S. hepatica on productivity of ruminants has not been elucidated through these surveys. Abattoir surveys could still be relied upon to estimate the economic significance of Fasciola, Stilesia and other liver parasites such as Dicrocelium species since this relies on postmortem meat inspection, a method with high accuracy and precision that results in very small error rates (Herenda et al., 1994; Thrusfield, 1995). The majority of abattoir surveys conducted in Kenya have estimated prevalence of fasciolosis in cattle to be between 18% and 57% (Castelino and Preston, 1979; Cheruiyot, 1983; Anon, 1986). S. hepatica in Kenya has been reported to occur in sheep and goats (Nginyi et al., 1993). Abattoir record surveys have estimated condemnation rates of 56% and 47% of total livers in slaughtered sheep and goats, respectively (Anon, 1986). This study was designed to establish the trend, prevalence and estimated losses associated with fasciolosis and S. hepatica infestation in the semi-arid parts of the Coastal region of Kenya over a period between 1989 and 2004. Materials and methods Study area and population Taveta is one of the six divisions of Taita Taveta district and lies between longitude 37 and 39 E and latitude 2 and 4 S. It borders Tanzania to the south, Tsavo national park to the east, and Mwatate division to the north-east. Much of the division is in agroecological zones 4 6, which lie in the semi-arid and arid area with an average annual bimodal rainfall ranging between 250 to 500 mm (Jaetzold and Schmidt, 1983). This is a region suitable for keeping small ruminants and beef cattle. The total land area is 645 km 2 with a human population of 53 038 people spread over a total of 12 346 households (Central Bureau of Statistics, 1999). Data collection This observational study was conducted between April 2005 and November 2005. A retrospective appraisal to collect both slaughter and liver selling price data was conducted using the divisional veterinary annual reports for the period January 1989 to December 2004. These data originated from field meat inspection reports of the 12 licensed slaughter slabs within the division. Four of these slaughter slabs were situated in the urban and peri-urban areas of Taveta, i.e. within a radius of < 15 km from town, whereas the rest were distant, > 15 km from Taveta town. Data on the annual total number of animals slaughtered and liver selling price were collected for the period under study. Liver condemnation information was also summarized from the total number of livers inspected. Other minor causes of liver condemnation such as pleurisy, congestion, presence of cysts (mainly hydatid cysts) and abscesses were

Trop Anim Health Prod (2006) 38:475 483 477 also reported in the postmortem meat inspection reports. These, however, were not used in the economic loss estimations. The prevalence of infestations was estimated by dividing the number of livers condemned for infestation with the respective parasite by the total number of animals from this species slaughtered in a given time interval. It is likely that information on light liver infections which are passed as fit for human consumption after trimming the affected parts during the routine postmortem inspection could have been omitted. Any month that did not have information was noted as missing value(s). For the annual prevalence estimates stage, the assumption was made that the missing values would have been normally distributed if they had been present. Several parameters were used to estimate the loss made by butchers owing to liver condemnations. The total number of cattle, goats and sheep slaughtered over the 16-year period was estimated from the retrospective data collected. Other parameters used included the overall prevalence of both fasciolosis and S. hepatica infections over the period, which represented the risk of liver condemnation, the average weight of liver in a mature animal (bovine and/or small ruminant) and the selling price of the cattle and small ruminant livers over the period 1989 to 2004. The price trends for livers of cattle and small ruminants between 1989 and 2004 were collected from both the divisional Veterinary and Livestock Production annual reports for the period under review. The livers were weighed immediately after slaughter using weighing balances. Information on the prevailing exchange rates for the Kenya shilling (KES) versus the United States dollar (USD) was collected from the Central Bank of Kenya, foreign exchange department (Central Bank of Kenya, 2005). Data analysis All the data were entered, stored and cleaned in MS Excel. The retrospective data were analysed using SPSS. Means were compared using the independent-samples t-test at 95% confidence level. The means of bovines were compared with those of caprines and ovines. The means of caprines and ovines were also compared using the independent-samples t-test. Losses accruing as a result of condemnations of livers due to fasciolosis were computed with MS Excel using the model: L x = (C F + C s ) Liver Wt x Price/kg of liver where subscript X denotes the type of animal slaughtered (bovine, caprine or ovine); thus L X = the loss made for condemning a bovine, caprine or ovine liver; C F = the number of livers condemned because of F. gigantica; C S = the number of livers condemned because of S. hepatica; Liver Wt x = the approximate weight of liver in a mature individual of the respective species; and Price/kg of liver = the average selling price of bovine, caprine or ovine liver over the 16-year period. Results Descriptive statistics of the divisional slaughter trends for the period under review are summarized in Table 1. A total of 23 606, 17 743 and 6 036 cattle, goats and sheep, respectively, were slaughtered in that division during the period 1989 2004. There were significant differences (p 0.05) in the mean numbers of animals slaughtered per year in the division for the period. Over 80% of the bovines were slaughtered at the four slaughter slabs sited within the vicinity of Taveta town because of stronger purchasing power there. Slaughter slabs farther away specialized in the slaughter of the small ruminants. The overall liver condemnation rate for fasciolosis (prevalence) for the 16 years under study was 26% in bovines, significantly higher than in caprines (6.6%) or ovines (5.2%). In bovines, the maximum fasciolosis liver condemnation rate was 35% in the year 1989 and a minimum of 15% recorded in the year 2002 (Fig. 1). Seasonal variation was limited, with the highest bovine liver condemnation rates (29.3%) in September and lowest (22%) in January (Fig. 2). The minimum annual prevalence for caprines was 1.5% in 1989; the maximum (14%) was recorded in 2001. As in bovines, seasonal variation was limited, ranging from 4.8% to 10.6% (Fig. 2). In ovines, the minimum annual prevalence was zero (2004). The maximum annual condemnation rate of 15.4% was recorded in 1995. Seasonal variation was between 2.0% and 7.7%. Liver condemnation rates attributed to S. hepatica were lower (0.4%) for all the bovines as compared to caprines (22%) and ovines (28%) (Table 1). The difference between caprines and ovines was also significant (p 0.05). The highest (2%) bovine S. hepatica liver condemnation rate was recorded in 1992, while zero liver condemnations occurred in 1990, 1991, 1996 1998, 2000 2004 (Fig. 3). No distinct seasonal pattern

478 Trop Anim Health Prod (2006) 38:475 483 Table 1 Slaughter statistics and liver condemnation rates for F. gigantica and S. hepatica for large and small ruminants between 1989 and 2004 in Taveta division Species slaughtered Bovines Caprines Ovines Number slaughtered (total livers) 23 606 17 743 6 036 Mean ± SD 1 475 ± 362 a 1 109 ± 478 b 377 ± 98 c Range 973 2 160 525 1941 368 545 (1187) (1416) (177) Liver condemnations F. gigantica condemned livers 6 079 (26% a ) 1 171 (6.6% b ) 314(5.24%) b 95 % confidence interval 22 28% 4.6 8.7% 3.1 7.3% S. hepatica condemned livers 99 (0.4% a ) 3 953 (22% b ) 1 712 (28% c ) 95 % confidence interval 0.3 0.5% 21.6 23% 27 30% Total livers condemned 6 178 (26.4 %) 5 124 (28.6%) 2 026 (33.2 %) Approximate weight of normal liver (kg) 4 1 1 Selling price of liver/kg (1989 2004) (ICES) 90 180 (135) 100 200 (150) 100 200 (150) Loss made in KES (USD) 3 336 120 768 600 303 900 (54 690) (12 600) (4 982) a,b,c Values with different superscripts in the same row are significantly different (p 0.05). Average liver selling price over the 16 years Fig. 1 Annual trends of liver condemnation in slaughtered bovines, caprines and ovines as a result of fasciolosis for the period 1989 2004 % Annual liver condemnations 40 30 20 10 Ovine Caprine Bovine 0 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 Period (Years) Fig. 2 Seasonal variations in proportions of livers condemned for fasciolosis during the years 1989 2004 % Livers condemned 40 30 20 10 Bovine Caprine Ovine 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months

Trop Anim Health Prod (2006) 38:475 483 479 Fig. 3 Annual trends of liver condemnations in both small and large ruminants due to Stilesia hepatica for the period 1989 2004 % Annual condemnation 50 40 30 20 10 Ovine Caprine Bovine 0 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 Period (Years) Fig. 4 Seasonal variations in proportions of livers condemned for Stilesia hepatica infestation during the years 1989 2004 % Livers condemned 40 30 20 10 Bovine Caprine Ovine 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months was observed (Fig. 4). The highest (40%) S. hepatica liver condemnation rate in caprines was recorded in 1989, while the lowest (10%) was in 1996. As with F. gigantica, seasonal variation was limited, with the lowest condemnation rates in August (18.9%) and highest (25.3%) in November (Fig. 4). In ovines, S. hepatica liver condemnations were highest (48%) in 1989 and lowest (15%) in 1996, with the highest condemnation rates (31.8%) in April and lowest (22.5%) in June. Economic losses The price of a kilogram of liver for the period 1989 2004 ranged between 90 and 180 KES for bovine liver and 100 and 200 KES for both caprine and ovine liver. From the measurements taken at the slaughter slabs and butchery shops, a mature bovine s normal liver (without pathological lesions arising from F. gigantica and/ or S. hepatica infestation) weighed approximately 4 kg and that of a mature caprine or ovine about 1 kg. Economic losses following liver condemnations in slaughtered animals for the period under review due to F. gigantica and S. hepatica are computed and presented in Table 1. The total loss for the slaughtered animals together was 4 408 620 KES (72 272 USD) for the 16 years. The proportion of loss attributed to bovines, caprines and ovines was 76%, 17% and 7%, respectively. The loss due to fasciolosis was 3 505 410 KES (57 466 USD), out of which 3 282 660 KES (53 814 USD) was attributed to liver condemnations in bovines and the remainder in caprines and ovines. Liver condemnations for S. hepatica infestation in all species contributed 903 210 KES (14 807 USD) of which 53 460 KES (876 USD), 592 950 KES (9720 USD) and 256 800 KES

480 Trop Anim Health Prod (2006) 38:475 483 (4210 USD) was attributed to bovines, caprines and ovines, respectively. Discussion The slaughter trend showed a general decline over the period under consideration. This period was characterized by depressed purchasing power. The poverty index in Kenya increased significantly during the period 1993 2004, with over 56% of the Kenyan population falling below the poverty line, i.e. surviving on less than 1 USD per day (Government of Kenya, 2003). The results showed that few sheep were slaughtered in Taveta division over the period under review. The division is composed of about 45% of Akamba people, a community that has traditional beliefs that discourage the slaughtering and eating of sheep (Bauni et al., 2004; MoL&FD, 2004). Fasciolosis liver condemnation trends are shown in Fig. 1. More bovine livers were condemned over this period than in both caprines and ovines. Since the life cycle of the Fasciola species is dependent on amount and pattern of rainfall, high condemnation rates were observed during the years 1989, 1992, 1994, 1995, 1997 and 1998 2001 for both large and small ruminants. These years were generally wetter, with annual average rainfall amounts of about 600 mm rather than the < 500 mm received in the rest of the years considered (Jaetzold and Schmidt, 1983; MoL&FD, 2004). This observation agrees with the observations from other parts of Africa, where significantly increased fasciolosis pressure in both live and slaughtered bovines was reported following periods of high rainfall (Pfukenyi and Mukaratirwa, 2004; Keyyu et al., 2005). However, no distinct seasonal pattern in condemnation rates could be observed, which might be due to the chronic nature of the infestation, which levels out short-term differences in infection pressure caused by wet and dry seasons. This study established a mean overall fasciolosis prevalence of 26% in bovines. A previous fasciolosis survey in Kenya categorized bovine fasciolosis prevalence estimates into three group: low (0 10%), medium (10 40%) and high prevalence (40 90%) (Anon, 1986). The findings of this study fitted well in the medium category. Kithuka and colleagues (2002) established a fasciolosis prevalence rate across Kenya of 8% from a retrospective abattoir survey spanning 10 years and a 9.3% prevalence estimate for the same from a 2-month meat inspection exercise at a busy slaughterhouse. These estimates were lower than those of the current study. A similar study in Zimbabwe, however, established a higher prevalence of 31.7% (Pfukenyi and Mukaratirwa, 2004). Fasciolosis prevalence in live animals in central Kenya was estimated to be 34% using copro-parasitological worm egg counts (Waruiru et al., 2000). The study by Waruiru and colleagues (2000) used dairy cattle, which are much more susceptible to fasciolosis compared to the local cattle that were slaughtered in the Taveta slaughter slabs (Castelino and Preston, 1979). Given the large size of the bovine liver, it is also possible that the fasciolosis prevalence in the current study is underestimated, since some livers with partial infection could have been passed as fit for human consumption after trimming of the affected parts. In ovines and caprines, the prevalence of F. gigantica in Kenya based on abattoir surveys has been found to be generally low, ranging between 0.3% and 4.4% (Nginyi et al., 1995). The current study established higher prevalence estimates of 6.6% and 5.2% for caprines and ovines, respectively. The difference between the two estimates could be attributable to differences in the drainage situation in the two areas. Kiserian, where Nginyi and colleagues 1995 carried out their investigation, has better drainage than Taveta owing its higher altitude. Taveta is situated in the coastal lowlands and has very poor drainage, which has resulted in pools of water that are habitats for the snails that harbour the infective stages (metacercariae) of Fasciola parasites. Fasciolosis has been reported to impact negatively on the production and productivity of small ruminants. Studies have shown that a majority of caprines and ovines are killed by acute fasciolosis while still on the farms and hence are not presented for slaughter (Cheruiyot, 1983, 1987; Hansen and Perry, 1994; Nginyi et al., 1995). There is little evidence of any acquired immunity to fasciolosis in sheep and goats and the effect of additional infections is additive as far as pathogenicity is concerned (Hansen and Perry, 1994). Bovines, on the other hand, are less susceptible than ovines and caprines and, following the first infection, immunity develops that reduces the migration of the immature flukes in subsequent infections. The development of fibrosis of the liver, calcification of the bile ducts and acquired immunity may be responsible

Trop Anim Health Prod (2006) 38:475 483 481 for the elimination of the infection, which occurs in some animals. These observations could help explain why only 5.2% and 6.6% of ovines and caprines livers were condemned in the current survey. The majority could have succumbed to acute disease before attaining slaughter age, unlike cattle, which are more resistant and tend to harbour the chronic form of the disease. Generally, the condemned livers were those from animals that had the chronic form of the disease as opposed to the acute disease that tends to kill the host animals. The overall prevalence of S. hepatica in bovines, caprines and ovines was 0.4%, 22% and 28%, respectively. While prevalence showed a wave-like pattern over the years, it was fairly independent of the time of year. This parasite contributed much more to the public health concerns of small-ruminant meat consumers rather than it did to those of beef consumers. It rarely occurred in bovines, but was frequently encountered during postmortem liver inspection of small ruminants. Stilesia hepatica affected livers may show signs of mild cirrhosis with thickening of the bile ducts (Hansen and Perry, 1994). Heavy infestations are frequently seen in apparently healthy ovines and caprines, with complete occlusion of the bile ducts. Icterus and other clinical signs are not commonly observed. At meat inspection, condemnation is for ethical reasons rather than the presence of the parasites in the liver. The parasite s epidemiology in small ruminants is poorly understood. Investigations have reported 19% Stilesia globipunctata infections in camels in Ethiopia (Bekele, 2002). S. hepatica has also been reported in impala in Swaziland (Gallivan et al., 1996). Other studies have reported Stilesia parasites in the liver of sheep, goats and impala in Kenya and southern Africa (Nginyi et al., 1993; Louw, 1995; Gallivan et al., 1996) The frequency of occurrence has not been quoted, since little work has been conducted on this parasite. However, Stilesia prevalence is high (>60%), especially considering postmortem liver condemnations and coproparasitological analysis (Nginyi et al., 1995). This estimate is higher than that reported by the current study. The resultant loss following condemnation was felt most by liver consumers and butchers. The quality of liver deteriorated owing to the resultant inflammatory responses that caused fibrosis of the liver following infestation by these parasites. However, this was treated as a qualitative attribute that only the consumers felt and could describe. Animals with fasciolosis lose body condition, resulting in lighter carcasses and lower meat quality than in healthy animals. Tangible estimated losses were made by butchers following condemnations of livers in slaughtered animals. Fasciolosis in bovines accounted for a larger portion (> 99%) of liver condemnations as compared to only <1% attributed to S. hepatica. Conversely, S. hepatica accounted for 79% and 84% losses in total liver condemnations in caprines and ovines slaughtered, respectively. Bovine fasciolosis contributed about 75% of the total losses for the 16 years studied. Fasciolosis in bovines tended to be chronic and was only observed on the slaughter floor through extensively fibrotic livers (liver cirrhosis). Both crude and proportional bovine fasciolosis losses are greater than the crude losses (0.5 USD) and proportional losses (6.1 USD) in the same species established by Kithuka and colleagues (2002) in their 10-year abattoir survey study. Losses due to liver condemnations as a result of S. hepatica were mainly observed small ruminants rather than in bovines. Out of 6178 livers condemned in bovines slaughtered, only <2% were attributed to S. hepatica, as opposed to 61% of the 5124 and 85% of the 2026 livers condemned in caprines and ovines, respectively. Despite the large percentages of liver condemnations due to S. hepatica in small ruminants, these contributed only 13% and 6% of the total losses since small ruminant livers are smaller and weigh only about 1 kg as compared to the bovine liver weight of about 4 kg. Fasciolosis and S. hepatica infestation are diseases that cause significant losses to farmers, butchers and consumers. Both lead to destruction of the liver of affected animals. There are other additional losses such poor carcass quality and quantity due to interruption of the liver metabolic functions of animals infested with Fasciola and Stilesia parasites. We therefore consider that the disease should be investigated further on farms to determine the prevalence in animals of various ages, species and breeds and to develop economic strategies for disease control at farm level. Acknowledgements We acknowledge the invaluable support extended to us by the Director General of the Kenya Agricultural Research Institute (KARI) and the Centre Director of KARI Katumani, without which this work would not have been accomplished. Funding to carry out this work came from the Kenya Agricultural Productivity Project (KAPP), a World Bank - funded project, for which we are very grateful.

482 Trop Anim Health Prod (2006) 38:475 483 References Anon, 1986. Distribution and Economic Impact of Liver Fluke in Kenya, (Agricultural Research Foundation, Kenya.) Bauni, S.M., Mungube, E.O., Lutta, W.M. and Mutuoki, T.K., 2004. A survey on feed resources and small ruminant breeds in the Machakos, Makueni and Kitui districts, of Kenya. KARI-Katumani Quarterly Reports for the March June 2005 Quarter Bekele, T., 2002. Epidemiological studies on gastrointestinal helminths of dromedary (Camelus dromedarius) in semiarid lands of Eastern Ethiopia. Veterinary Parasitology, 105, 139 152 Castelino, J.B. and Preston, J.M., 1979. The influence of breed and age on the prevalence of bovine fasciolosis in Kenya. British Veterinary Journal, 135, 198 203 Central Bank of Kenya, 2005. The Foreign Exchange Database for 1985 2004 Central Bureau of Statistics, 1999. National Census of Kenya, August 1999 Cheruiyot, H.K., 1983. Bovine helminth parasites of economic importance abattoir survey in Kenya. 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La prévalence et les pertes économiques causées par Fasciola gigantica et Stilesia hepatica dans les systèmes de production des ruminants de la division de Taveta au Kenya ont été estimées dans le cadre d une estimation rétrospective des dossiers d abattage portant sur le nombre d animaux abattus et de foies condamnés durant le période 1989 à 2004. Seules les condamnations de foies basées sur une infestation par F. gigantica et S. hepatica ont été envisagées pour les objectifs de cette étude. Les taux de condamnation ont considérablement différé entre les bovins, les caprins et les ovins (p 0.05) pour F. gigantica (26%, 6.6% et 5.2% respectivement) ainsi que pour S. hepatica (0.4%, 22% et 28% respectivement). La perte totale enregistrée par la condamnation tant des foies infestés par F. gigantica que par S. hepatica a été de 4,408,272 Ksh. (72,272 $ US). La proportion de pertes chez les bovins, les caprins et les ovins a été de 76%, 17% et de 7% respectivement. L infestation par la fasciolose a contribué 3,505,410 Ksh (79,5%) et par S. hepatica 903,210 Ksh (20.5%) aux pertes totales imputables aux condamnations de foies. Les auteurs ont la ferme conviction que davantage de travail devrait être entrepris sur les

Trop Anim Health Prod (2006) 38:475 483 483 deux parasites en utilisant des animaux vivants pour déterminer sa prévalence dans des animaux de divers âges, espèces et races ainsi que pour circonscrire l économie du contrôle des maladies au niveau de la ferme. Prevalencia y significación económica de Fasciola gigantica y Stilesia hepatica en animales sacrificados de la zona costera semiárida de Kenia Resumen Fasciola gigantica y Stilesia hepatica limitan la productividad rumiante. Se estimaron la prevalencia y las pérdidas económicas causadas por Fasciola gigantica y Stilesia hepatica en los sistemas de producción rumiante de la división Taveta de Kenia en una evaluación retrospectiva de los registros de matanzas del número total de animales sacrificados e hígados desechados durante el periodo 1989 a 2004. Sólo se consideraron para propósitos de este estudio los desechos de hígados infestados por F. gigantica y S. hepatica. Los índices de hígados desechados diferían significativamente entre bovinos, caprinos y ovinos (p 0.05) para F. gigantica (26%, 6.6% y 5.2%, respectivamente) así como para S. hepatica (0.4%, 22% y 28%, respectivamente). La pérdida total efectuada al desechar los hígados infestados de F. gigantica y S. hepatica fue de 4408,272 chelines kenianos (72272 dólares de EEUU). La proporción de pérdida en bovinos, caprinos y ovinos, fue de 76%, 17% y 7%, respectivamente. La Fasciolosis contribuía a una pérdida de 3505,410 (79.5%) chelines kenianos y la infestación por S. hepatica suponía 903,210 (20.5%) chelines kenianos del total de las pérdidas debido a desechos hepáticos. Los autores de este estudio creen firmemente que hace falta más trabajo sobre los dos parásitos utilizando animales vivos para determinar la prevalencia en animales de distintas edades, especies y razas, y para la política económica del control de la enfermedad a un nivel de granja.