Browsing by Author "Laisser, E. L. K."

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Characterization of Tanzania shorthorn zebu cattle for tolerance to ticks and East Coast Fever
(Sokoine University of Agriculture, 2017) Laisser, E. L. K.
In Tanzania, livestock diseases, especially tick bone diseases (TBDs), impose loses to livestock in terms of mortality, decrease in production and increased costs of control measures. Among the TBDs, East Coast fever (ECF) is the most prevalent and fatal disease. The main control measure for TBDs is use of acaricides to control the vector ticks, chemotherapy of sick animals as well as immunization of cattle by the infection and treatment method (ITM). The applications of these are control measures are often limited by high costs of acaricides and veterinary drugs, development of resistance by vector ticks and the parasites as well as negative environmental impacts. This necessitated the search for alternative ways to control TBDs with minimum use of acaricides. Indigenous breeds of cattle are said to be tolerant to TBDs and adapted to harsh conditions prevailing in rural areas. Among the Tanzania Shorthorn Zebu (TSHZ) cattle, Tarime cattle are believed by livestock keepers to be tolerant to ticks and ECF. However, there are no scientific investigations which have been conducted to verify the farmers’ beliefs. Therefore, studies were conducted to validate the farmers’ belief that Tarime cattle are tolerant to ECF. In the first study, a cross-sectional survey was conducted in four selected districts of Mara (Serengeti and Tarime) and Simiyu (Maswa and Meatu) regions to determine the perception of livestock farmers on ticks, tick-borne diseases and tolerance of their cattle to TBDs. In the second study, tick burden and prevalence of Theileria parva (T. parva) infection in Tarime cattle found in Serengeti and Tarime districts were assessed. In the third study, an on-station experiment was conducted to compare tick burden and induced immunity due to T. parva infection in Tarime and Sukuma zebu cattle under different tick control regimes. The fourth study was a review on tolerance of TSHZ cattle to ticks and ECF. In the first study, a well structured questionnaire and personal observation were used to collect information. The aim of the study was to assess farmers’ knowledge and perceptions on tick species, tick-borne diseases, tick control measures, production constraints and tolerance of Tarime and Sukuma zebu cattle to TBDs. The study involved 60 agro-pastoralists from each of the districts of Serengeti, Tarime, Maswa and Meatu in Tanzania, making a total sample size of 240 livestock farmers. Data were collected through individual interview using a structured questionnaire. The results show that, livestock diseases were ranked as the first important problem affecting cattle production in Serengeti and Tarime districts while in Maswa and Meatu districts lack of livestock feeds during the dry season was ranked as the most important constraint, followed by livestock diseases. Among the diseases affecting cattle, the TBDs ranked first in Serengeti and Tarime districts while in Maswa and Meatu districts the TBDs ranked fourth and sixth, respectively. Most (74%) of the livestock farmers interviewed knew well the signs of the different TBDs. The majority of the respondents in all districts knew that ECF is caused by ticks, but did not associate the other TBDs with ticks. Most of the farmers interviewed were using acaricide to control ticks, and the most common method of application was hand spraying. All farmers used Oxytetracycline to treat TBDs, however, some farmers used local herbs. Although most farmers knew the signs of TBDs, they were not spraying/dipping their animals on regular basis due to economic reasons and the belief that their animals always carry ticks without being sick or dying and ECF affects only calves. About half of the farmers considered their breeds to be tolerant to ticks and ECF. It is concluded that, the livestock farmers in the Lake zone have substantial knowledge on tick species and TBDs symptoms and they consider ECF as less important disease compared to the other TBDs. The second study was carried out to assess the distribution, abundance of different tick species and the prevalence of T. parva infection in Tarime zebu cattle kept in selected wards of Serengeti and Tarime districts in Mara region. Adult ticks were sampled, identified and counted from 360 animals which were extensively managed in communal rangelands. Concurrently, blood samples were collected and thereafter DNA extracted and nested polymerase chain reaction (nPCR) carried out to determine the prevalence of T. parva. Two primers specific for p104 gene were used in PCR amplification to detect the presence of T. parva DNA. Four genera of ticks, namely, Rhipicephalus, Amblyomma, Boophilus and Hyalomma were identified. Rhipicephalus spp accounted for 71.8% of the total ticks whereas Amblyomma, Boophilus and Hyalomma constituted 14.1%, 14.0% and 0.1% of the ticks, respectively. There was significantly (p < 0.05) more animals infested with ticks in Tarime district (96.1%) than in Serengeti (61.7%). The average counts of ticks were higher in adult animals (p < 0.05) than in young animals. The overall prevalence of T. parva was 27.7% and was significantly (p < 0.05) higher in Serengeti (38.3%) than in Tarime district (16.7%). Interestingly, it was observed that, all animals which tested positive for T. parva did not show any clinical signs of ECF, suggesting existence of subclinical infection in Tarime zebu. These results suggest that Tarime cattle can tolerate ECF infection and are likely to save as potential carriers of T. parva to other less tolerant cattle breeds in mixed herds. Since Tarime cattle are preferred by most farmers with mixed herds, routine screening for T. parva is highly recommended to minimize introduction of infected cattle into an immunologically naive population. The third study was conducted to determine tick burden and immunological parameters of resistance to ECF in Tarime and Sukuma zebu strains exposed to natural tick infestation. Tick load, Packed Cell Volume (PCV), T. parva specific antibody percent positivity (PP) and prevalence of T. parva parasites were studied in relation to dipping regime, breed, and season of the year. A total of 25 animals per strain were used in this experiment. Animals of each strain were divided into three groups. Animals in group I were dipped every two weeks while those in group II were dipped every three weeks. Animals in group III were not dipped at all. Comparison of effect of dipping frequency on tick burden showed no significant (p > 0.05) differences when cattle which were dipped in each strain either once every 2 or 3 weeks in the two seasons. However, Tarime cattle had significantly higher (p < 0.05) tick count than Sukuma cattle and non dipped groups maintained high tick infestation throughout the experimental period. The PCV values in all cattle were within the normal physiological range; although this parameter was significantly lower (p < 0.05) in Tarime cattle. All cattle regardless of breed were sero positive (had antibody levels above ELISA cut-off point), but Tarime cattle maintained higher antibody percent positivity compared to Sukuma cattle by 15%. Conversely, the prevalence of T. parva parasites was lower in Tarime (36%) compared to Sukuma cattle (38%), although the difference was not significant. During the study period 20% (5/25) of Sukuma cattle contracted ECF, but none of the Tarime cattle showed any clinical signs for the disease. The differences between the two zebu strains shown in terms of antibody percent positivity and T. parva parasite prevalence indicate different ability of the two cattle strains to resist tick infestation and ECF infection under natural challenge. Thus, the higher antibody levels but lower parasite prevalence under high tick challenge observed in Tarime cattle, suggests a high proportion of individual animals in this strain, which are carriers of T. parva. Thus, these findings confirm the farmers’ perceptions on suitability of Tarime cattle under prevailing ecological conditions in the Lake zone of Tanzania. The fourth study was a review on the prevalence and tolerance of Tanzania Shorthorn Zebu cattle to East Coast fever in Tanzania. A search of peer-reviewed publications on ECF, ticks and ECF tolerant cattle in Tanzania was conducted from comprehensive databases including PubMed, Science Direct, Swetswise and CAB direct. The search was extended to available theses, conference proceedings and project reports. The findings show that ECF is not seen by most livestock keepers as the most serious disease compared to other TBDs. This is because the zebu cattle which are predominantly kept all over the country are thought to be tolerant to ticks and ECF. Some of the zebu strains which are thought to tolerate ECF are Sukuma, Tarime, Maasai and Fipa cattle. In all agro ecological zones the most prevalent tick species is R. appendiculatus, this implies that the TSHZ cattle are at risk of being infected with ECF if the animals are not resistant and proper tick control regimes are not observed. In Tanzania, ECF control has mainly relied predominantly on tick control using acaricides and chemotherapy while ECF immunization has been recently introduced. Some research results also showed that, immunization can boost immune status of indigenous cattle and, if ECF immunization can be sustained, large areas are expected to be endemically stable. However, the adoption of immunization on wider scale is questionable due to its cost and change in farmers’ attitudes, socio-demographic and environmental concerns. The study recommends interdisciplinary collaboration between veterinary epidemiologists, socio and agricultural economists and ecologists not only to find a single most suitable method of ticks and ECF control but to integrate the available methods with tolerant strains of cattle available to create endemic stability condition for the disease which can reduce the complexity of the whole process. Generally, the findings of this study confirm farmers’ perception on the ability of Tarime cattle to tolerate ECF infection under prevailing ecological conditions in the Lake zone of Tanzania. The use of this strain, therefore, can be an alternative way of minimizing acaricide usage, whereby application can be done on monthly basis. However, when Tarime and other breeds are kept together, screening of the animals for presence of T. parva parasites is recommended. From these findings it is concluded that using Tarime cattle could be effective and economical in rural areas as it minimizes the use of synthetic acaricide to control ticks and TBDs. Further research studies to determine the gene responsible for tolerance of Tarime cattle to ECF are recommended.
Tick burden and acquisition of immunity to Theileria parva by Tarime cattle in comparison to Sukuma cattle under different tick control regimes in the Lake Zone of Tanzania
(2016-03) Laisser, E. L. K.; Chenyambuga, S. W.; Karimuribo, E. D.; Msalya, G.; Kipanyula, M. J.; Mwilawa, A. J.; Mdegela, R. H.; Kusiluka, L. J. M.; Gwakisa, P. S.
This study was conducted to determine tick burden and immunological parameters of resistance to East Coast fever (ECF) in Tarime and Sukuma cattle. Tick load, packed cell volume (PCV), Theileria parva (T. parva) specific antibody percent positivity (PP), and prevalence of T. parva parasites were studied in relation to dipping regime, strains, and season. A total of 50 experimental cattle were included in this study. Tick load was determined by whole body counts, antibody percent positivity was determined by the polymorphic immunodominant molecule (PIM)-based T. parva enzyme-linked immunosorbent assay (ELISA), and prevalence of T. parva parasites was detected by a nested polymerase chain reaction (PCR) based on the p104 gene. Dipping frequency on tick burden showed no statistically significant differences when cattle of either strain were dipped either once every 2 or 3 weeks in the dry and wet seasons. However, Tarime cattle had higher (p<0.05) tick count than Sukuma cattle and non dipped groups maintained high tick infestation throughout the experimental period. The PCV values were within the physiological range, although this parameter was lower in Tarime cattle (p<0.05). All cattle regardless of strain were seropositive, although Tarime cattle maintained higher PP compared to Sukuma by 15%. Conversely, the prevalence of T. parva parasites was lower in Tarime (38%) compared to Sukuma cattle (38.5%), but the difference was not significant (p>0.05). During the study period, 20% (5/25) of Sukuma cattle contracted ECF, but none of the Tarime cattle showed clinical signs for the disease. The differences between the two strains shown in terms of PP and T. parva parasite prevalence may indicate the ability of individual cattle to resist tick infestation and ECF infection under natural challenge. Higher antibody levels but lower parasite prevalence attained by Tarime cattle, suggests inherent ability of Tarime cattle to resist clinical development of ECF infection, but to remain as T. parva carriers.