Protective efficacy of isometamidium chloride and diminazene aceturate against natural <i>Trypanosoma brucei<i/>, <i>Trypanosoma congolense<i/> and <i>Trypanosoma vivax<i/> infections in cattle under a suppressed tsetse population in Uganda

The protective efficacy of isometamidium chloride (ISMM) and diminazene aceturate (DIM) against Trypanosoma brucei, Trypanosoma congolense and Trypanosoma vivax infections in cattle under a suppressed tsetse population was assessed in southeast Uganda. A total of 66 and 57 trypanosome-infected cattle were treated with ISMM and DIM, respectively together with 177 trypanosomefree animals not treated were followed for 12 months, checked every 4 weeks. There was no statistical difference in the mean time to infection with any trypanosome species in animals treated with ISMM or DIM. However, the mean time to trypanosome infection was significantly longer for treated animals than controls. The mean time to infection with each of the three trypanosome species differed significantly, with the average time to T. vivax infection the lowest, followed by T. congolense and then T. brucei. The protective efficacy of DIM was as good as that of ISMM; implying curative treatments against trypanosomosis are sufficient for combination with tsetse control. Isometamidium chloride or DIM had the highest impact on T. brucei and T. congolense infections in cattle

The diagnosis of trypanosome infections: applications of novel technology for reducing disease risk

Reliable DNA based methodologies to determine prevalence of trypanosome species in domestic livestock have been available for over 10 years. Despite this, they are rarely used to generate baseline data for control operations for these diseases in the field. Rather, such operations tend to rely on data which can be generated using low technology methods such as direct observation of parasites by light microscopy. Here we show the pitfalls of relying on such low tech methodology which, although simple in its application, can provide inaccurate and inadequate data on which to base control methodologies. Our analysis of 61 cattle selected for trypanosome carrier status by either microscopy, low PCV or poor condition score, showed that 90% were infected with trypanosomes while 84% of the total were infected with T. brucei. Diagnosis by PCR on buffy coat preparations on Whatman® FTA® matrices was the most sensitive methodology relative to the gold standard, whereas microscopy was the least sensitive. (African Journal of Biotechnology: 2002 1(2): 39-45

Point of care diagnosis of bovine trypanosomosis, tick-borne diseases and helminthoses with emphasis on portable anaemia-detection devices and decision support systems.

Effective diagnosis of major endemic bovine diseases such as trypanosomosis, tick-borne diseases and helminthoses that constrain agricultural production in sub-Saharan Africa is required for their rational treatment. However, this is hampered by the shortage of professional staff and unavailability of simple field-level diagnostic tests. The work presented in this thesis was designed to evaluate simple diagnostic tools and develop guiding decision support tools to facilitate diagnosis and treatment of these diseases in rural areas of Africa. Portable haemoglobinometers such as the Haemoglobin Colour Scale (HCS), HemoCue (HCU) and DHT -haemoglobinometer (DHT), commonly used in human medicine, were evaluated for their suitability in the detection of anaemia in cattle. Coefficients of variation (CY) were calculated for all methods to determine their precision over a range of 0-17 g/dl. The precision of the HCS (CV 2.9-8.8%) and HCU (CV 3.5-10.6%) was better than that of the DHT (CV 7.7-23%). There was good linearity between the readings of the HCS (R =: 0.925), HCU(R =: 0.920) and DHT (R =: 0.906) and those of the reference method (cyanmethaemoglobin). The diagnostic sensitivity and specificity of all methods for detection of anaemia (haemoglobin (Hb) 8 g/dl) as negative. The sensitivity ofthe HCS (94%) and HCU (80.5%) was high, but that of the DHT was low (52.7%). All the haemoglobinometers had high specificity: HCS (93%), HCU (96.5%) and DHT (100%). A high correlation between the packed cell volume (PCy) and Hb measurements was obtained using all methods: HCS (R =: 0.974), HCU (R =: 0.965) and DHT (R =: 0.934). Field veterinarians achieved good precision with the HCS (CV 8 - 13%) and the HCU (CV 1%). The cost of the kit and reagents for analysis of 1000 samples would amount to US$22 (? 19.50) for the HCS, US$ 600 (? 532) for the DHT and US$ 1100 (? 975) for the HCU, making the HCS cheapest to run. These haemoglobinometers are potentially useful for penside detection of anaemia, especially in rural areas of Africa. The influence of time of day and coat colour of Zebu cattle under tropical conditions on rectal temperature was assessed. The time of the day and coat colour had a highly significant influence on rectal temperature (P< 0.001) and thus need to be considered while assessing pyrexia during clinical diagnosis. The period between 13.00 and 17.00 hours was the most suitable time of the day for veterinarians to detect pyrexia, however there is the likelihood of picking healthy cattle (false positives) that have raised rectal temperature. Since veterinarians are usually presented with sick rather than healthy animals by farmers, it is unlikely that picking healthy animals would be a problem, Diurnal variations of the sensitivity of the common parasitological diagnostic tests for trypanosomosis were investigated. Despite the small sample size (n =: 2), the highest detection rate was observed at 21.00 hr and the lowest at 13.00 hr. Neither time of the day nor day-to-day variation had a significant influence on the sensitivity of the tests, despite occurrence of diurnal variations. Nevertheless, these results suggested optimal detection rate of trypanosomiasis with microscopy was achieved when cattle blood was taken and examined between 17.00 and 09.00 hours under tropical conditions. Epidemiological studies were conducted on endemic diseases in Zebu cattle kept under the mixed croplivestock production system in South East Uganda. Moderate parasitological prevalences of the diseases: anaplasmosis (23.6%), theileriosis (21.6%), fasciolosis (13.6%), Parasitic gastroenteritis (pGE) (6.7%), trypanosomosis (4.4%) and babesiosis (1.0%) were found. Morbidity rate

A retrospective sero-epidemiological study on rift valley fever in cattle in Uganda between 1997 to 2009

Surveillance on Rift Valley fever (RVF) in cattle was conducted in Uganda, with a view to ascertaining whether the RVF virus circulated in bovine undetected during the period 1997 to 2009. Four hundred eighty (480) frozen bovine sera collected in 1997, 1998, 2000, 2001 and 2005 were tested using both RVF IgG and IgM ELISA performed in parallel. Additional 685 bovine sera collected in 2006 and 2007 were tested using the Virus Neutralization Test (VNT). A further 232 and 296 bovine sera collected in 2008 and 2009, respectively, were tested using IgM ELISA. The findings revealed a prevalence of anti-RVF virus IgG antibodies in cattle ranging from 0.0 - 2.5% across districts and 0.0 – 2.6% across years (1997 – 2005), without significant differences across districts or years. Meanwhile the prevalence of anti-RVF virus IgM antibodies in cattle ranged from 0.0 – 6.3% across districts and 0.0 – 2.6% across years (1997-2009). Cattle sampled in Kumi district were 7 times (Odds Ratio (OR) 7.0: 95% CL, 1.8-26.9) more likely to be seropositive than those from other districts. Furthermore, cattle sampled in 2008 were 3.4 times (OR 3.4: 95% CL 1.0-10.1) more likely to be seropositive than during other years. Regarding analysis of anti-RVF virus neutralizing antibodies, cattle from Apac district were 3.6 times (OR 3.6: 95% CL 1.9-6.7) more likely to be seropositive than those from other districts. In addition, cattle from large herds (&gt; 100) were 5 times (OR 5.0: 95 CL 2.3 – 10.8) more likely to be seropositive than those from small herds (0-50). Arungi farm in Apac district had a higher likelihood (OR 4.0: 95 CL 1.8-9.3) to have seropositive cattle. The majority of the 685 cattle (90%) had low titres (&gt; 1: 10) of neutralizing antibodies while few (10%) had high titres, ranging from 1:10 to &gt; 1: 80. In conclusion, the study revealed evidence of low level circulation of the RVF virus in cattle in Uganda in certain districts and farms, especially during certain years (2008) when flooding occurred.Keywords: IgG; IgM; RVFV neutralizing antibodies; Cattle; Ugand

A low cost decision support tool for the diagnosis of endemic bovine infectious diseases in the mixed crop-livestock production system of sub-Saharan Africa

Diagnosis and treatment of endemic infectious disease is crucial for productivity of cattle in rural sub-Saharan Africa, but shortages of trained veterinary professionals necessitate support for less well-trained cadres of animal health worker. A Delphi survey of veterinary experts provided quantitative information on key clinical signs associated with eight endemic bovine diseases, then heuristics and dendrogram analysis identified a reduced sign set to be incorporated in a diagnostic decision support tool implemented as a simple colour-banded card. One hundred and seventy disease-sign questionnaire returns were obtained from 32 veterinary research scientists and 14 veterinary practitioners. Preliminary validation of the decision support tool for 16 prototypical cases resulted in 'correct' diagnosis over 90% of the time. The card potentially serves as a training aid and aide-mæ#169;moire, and could improve the diagnostic competence of animal healthcare providers

Mapping the distribution of tsetse and animal trypanosomosis in selected districts of Uganda to facilitate targeting control measures

Declining Government resources and donor aid for tsetse and trypanosomosis control have compelled countries to delegate control activities to farm-level veterinary extension personnel. While effective control measures such as chemotherapy, tsetse-trapping and restricted insecticide-treatment of livestock exist, implementation of such measures en masse has become increasingly impractical. Therefore mapping the distribution of tsetse and trypanosomosis hotspots was undertaken to ease targeting control measures by district administrative units in Amuria, Dokolo and Kaberamaido districts of Uganda. The districts were divided into grid sites using the program Arcview GIS 3.2. Villages representing the grid sites were physically identified through ground-truthing. Parasitological and tsetse surveys were then conducted in each village to establish the prevalence of trypanosomosis in cattle and apparent tsetse density. A total of 2430, 1304 and 1392 cattle were tested in Amuria, Dokolo and Kaberamaido districts, of which 230 (9.5%), 144 (11.0%) and 106 (7.6%) were detected positive, respectively. At village level, the prevalence of trypanosomosis ranged from 1-24%, 1-28% and 2-18% in Amuria, Dokolo and Kaberamaido districts, respectively. Tsetse surveys conducted concurrently in the respective villages revealed apparent tsetse densities ranging from 0.0-2.4, 0.6-13.2 and 0.6-9.0 flies/trap/day (F/T/D) in Amuria, Dokolo and Kaberamaido districts, respectively. Glossina fuscipes fuscipes was the sole tsetse species caught. Matching apparent tsetse densities at village level with their corresponding prevalences of trypanosomosis revealed that Amuria district had low tsetse densities with high corresponding prevalences of trypanosomosis, suggesting that cattle were encountering a high proportion of infected tsetse. In contrast, Dokolo district had high tsetse densities with low to medium corresponding prevalences of trypanosomosis, suggesting cattle were encountering a low proportion of infected tsetse. Kaberamaido district had low tsetse densities with corresponding low to medium prevalences of trypanosomosis, suggesting that cattle were equally encountering a low proportion of infected tsetse. Mapping to highlight hotspots was anticipated to facilitate planning and prioritization of resources for targeting tsetse and trypanosomosis control by district departments of veterinary services.Keywords: Animal trypanosomosis; Control; mapping; prioritization of resources; Tsetse flies; Ugand

Effect of strategic deworming of village cattle in Uganda with moxidectin pour-on on faecal egg count and pasture larval counts : short communication

Strategic application of moxidectin pour-on (Cydectin(R)) was evaluated in Uganda for its effect on pasture larval counts and gastrointestinal nematode faecal egg counts in village cattle kept under tethering (semi-intensive) grazing management. The strategic deworming schedule involved treating cattle twice at an interval of 2 months, at the end of the 1st wet season and during the 2nd wet season. Two groups of 30 cattle, each consisting of a treated and a control group, were examined for nematode infections every 4 weeks from June 1999 to January 2000. The treated group had significantly lower mean faecal egg counts than the untreated groups (t-value = 2.47, P < 0.05). Generally, the pasture larval counts on treated farms were lower than on untreated ones, but not significantly so (t-value = 2.22, P = 0.068). Pasture larval counts with different nematode species on treated farms were lower than on untreated ones, but the differences were not significant for Haemonchus spp. (t-value=1.68, P=0.145), Oesophagostomum spp. (t-value= 1.87, P=0.111), Trichostrongylus spp. (t-value=1.93, P=0.102), Dictyocaulus spp. (t-value= -0.74, P=0.485) and Cooperia spp. (t-value=-1.00, P=0.356). Treated farms did , however, have significantly lower pasture larval counts of Bunostomum spp. (t-value=4.64, P<0.05). This study has revealed that the application ofmoxidectin pour-on on cattle has an effect on faecal egg count and pasture contamination under the tethering grazing system. Moxidectin pour-on and the strategic deworming schedule evaluated here could be used for the control of gastrointestinal nematode infections in cattle by small-scale farmers who practise tethering or semi-intensive grazing management in Uganda and other tropical countries, especially where there is a bimodal rainfall pattern

Diagnostic value of rectal temperature of African cattle of variable coat colour infected with trypanosomes and tick-borne infections

Diagnosis of major endemic bovine parasitic diseases in sub-Saharan Africa such as trypanosomosis, theileriosis, anaplasmosis, babesiosis; and cowdriosis is increasingly relying on clinical diagnosis due to deterioration of veterinary services and laboratory facilities. Pyrexia is a common clinical feature of aforementioned diseases whose detection relies on measurement of rectal temperature. The research undertaken in this study was aimed at assessing the effects of diurnal changes and variable coat colour of indigenous Nkedi Zebu cattle on the diagnostic value of rectal temperature under tropical conditions. The results revealed that variation in rectal temperature was significantly influenced by time of day it was taken and by the coat colour of the Nkedi Zebu cattle (P &lt; 0.001). Rectal temperature experienced diurnal changes: steadily rising to reach a peak at 17.00 h before declining. The mean rectal temperature of unhealthy cattle was significantly higher (P &lt; 0.05) than that of the healthy ones only between 13.00 and 17.00 h of the day. During which period the proportion of unhealthy cattle having a rectal temperature of 39.4 degrees C or higher was significantly higher than that of healthy ones (P &lt; 0.001). Regarding the variable coat colour of indigenous breeds, rectal temperature among cattle of different coat colours was significantly different (P &lt; 0.05). In conclusion it is important to consider diurnal changes in rectal temperature and differences due to variable coat colour of indigenous African breeds when measuring rectal temperature for assessing pyrexia, during clinical diagnosis of bovine trypanosomosis and tick-borne diseases that are endemic in many countries in sub-Saharan Africa