Eric Thys

Rhipicephalus (Boophilus) microplus: a most successful invasive tick species in West-Africa

The cattle tick Rhipicephalus (Boophilus) microplus is known to be a highly reproductive and efficient vector of Babesia bovis, two characters which make this tick a threat to livestock keeping in many continents. The authors identified this tick in Ivory Coast, West Africa, in 2007, and hypothesized the spread to be minimal, as this tick was not observed in previous years. To determine the extent of its distribution and to a lesser extent the possible impact of the tick on the livelihoods of Ivorian smallholders, a cross-sectional survey was carried out in the Abidjan and Agboville Departments of Ivory Coast, in April 2008. The results of the study reveal that the newly introduced tick has almost completely displaced all indigenous Rhipicephalus (Boophilus) species in the study area and gave rise to unsuccessful tick control, inappropriate pesticide use, loss of milk production and even increased mortality in dairy cattle.

Boophilus microplus ticks found in West Africa

Early in 2007, during a small-scale survey of the ticks infesting cattle in Azaguie about 50 km north of Abidjan, Ivory Coast, ticks, belonging to a species which to our knowledge had never been reported in West Africa before, were encountered. Boophilus microplus was the only member of this genus collected from cattle in the area. No Boophilus annulatus or Boophilus geigyi were recovered although they had previously been recorded in this region (Aeschlimann 1967). The collection site at Azaguie (5°37 15.63 N and 4°05 12.76 W) is situated at an altitude of 85 m above sea level and is best characterised as dense humid forest. The ticks were initially morphologically identiWed at the Institute of Tropical Medicine in Antwerp, Belgium, using the identiWcation manual of Walker et al. (2003), after which some were sent to the Faculty of Veterinary Science, University of Pretoria, South Africa for conWrmation. At the same time sequencing of the ITS2 region of some of the remaining specimens conWrmed the initial identiWcation. The exact means or route of introduction of B. microplus into the Ivory Coast has not been determined. It has, however, been documented that N’dama bulls were introduced from Lower Congo (Democratic Republic of Congo) in 1985, principally on to the Marahoue Ranch for genetic improvement and subsequently for the establishment of herds of improved cattle for local farmers (Shaw and Hoste 1987). As far as we know B. microplus does not occur in the Congo, nor has it ever been documented in the countries bordering the Ivory Coast. But it has been reported from Zambia immediately to the south (Berkvens et al. 1998).

Seroprevalence and Potential Risk Factors for Brucella Spp. Infection in Traditional Cattle, Sheep and Goats Reared in Urban, Periurban and Rural Areas of Niger

Introduction In Niamey, Niger, interactions within the interface between animals, humans and the environment induce a potential risk of brucellosis transmission between animals and from animals to humans. Currently, little is known about the transmission of Brucella in this context. Results 5,192 animals from 681 herds were included in the study. Serum samples and hygroma fluids were collected. A household survey enabled to identify the risk factors for transmission of brucellosis. The true adjusted herd-level prevalence of brucellosis ranged between 11.2% and 17.2% and the true adjusted animal-population level prevalence was 1.3% (95% CI: 0.9–1.8%) based on indirect ELISA test for Brucella antibodies. Animals aged of 1–4 years were found to be more susceptible than animals less than 1 year old (Odds ratio [OR] of 2.7; 95% CI: 1.43–5.28). For cattle, the odds of brucellosis seropositivity were higher in rural compared to the periurban areas (OR of 2.8; 95% CI: 1.48–5.17) whereas for small ruminants the risk of seropositivity appeared to be higher in urban compared to periurban areas (OR of 5.5; 95% CI: 1.48–20.38). At herd level, the risk of transmission was increased by transhumance (OR of 5.4; 95% CI: 2.84–10.41), the occurrence of abortions (OR of 3.0; 95% CI: 1.40–6.41), and for herds having more than 50 animals (OR of 11.0; 95% CI: 3.75–32.46). Brucella abortus biovar 3 was isolated from the hygromas. Conclusion brucellosis in Niger is a serious problem among cattle especially in the rural areas around Niamey and among sheep in the urban areas of Niamey. The seroprevalence varies across strata and animal species with important risk factors including herd size, abortion and transhumance at herd level and age at animal population level. For effective control of brucellosis, an integrated approach seems appropriate involving all stakeholders working in public and animal health.

Bovine Tuberculosis Prevalence Survey on Cattle in the Rural Livestock System of Torodi (Niger)

Background Bovine tuberculosis (BTB) is a widespread zoonosis in developing countries but has received little attention in sub-Saharan Africa, especially in Niger. Recent investigations confirmed the high incidence of the disease in cattle slaughtered in an abattoir in Niamey. The fact that most of the animals in which M. bovis has been identified were from the rural area of Torodi implied the existence of a probable source of BTB in this region. This study aimed to determine the prevalence of BTB infection in cattle and to identify risk factors for infection in human and cattle populations in Torodi. Methods and Principal Findings A survey was carried out at the level of households keeping livestock (n = 51). The questionnaire was related to the potential risk factors and the presence of clinical signs of TB both in animals and humans. Comparative Intradermal Tuberculin Test was conducted to determine the TB status in cattle (n = 393). The overall apparent individual animal prevalence of tuberculin reactors was 3.6% (CI: 95%, 1.9–5.9), whereas the individual true prevalence was estimated at 0.8% (CI: 95%, 0.0–5.0). Using a multivariate logistic regression analysis and a classification tree analysis, the only household level risk factor that significantly influenced the presence of BTB in cattle was the presence of animals coughing in the herd (OR = 4.7, 95% CI: 1.12–19.71, p-value = 0.034). The lack of the practice of quarantine was borderline significant (OR = 4.2, 95% CI: 0.96–18.40, p-value = 0.056). Conclusion/Significance The study confirmed that BTB is endemic in cattle in Torodi and the risk of the transmission of the disease to humans is potentially high. For the control of the disease in livestock, slaughtering of infected animals and the compensation of the owners is needed. Collaboration between the veterinary and the medical sectors, in the diagnosis, monitoring, prevention and control of BTB is strongly encouraged.

Risk factors associated with brucellosis seropositivity among cattle in the central savannah-forest area of Ivory Coast

Serological results obtained from 907 serum samples collected from unvaccinated cattle of at least 6 months of age in the savannah-forest region of Ivory Coast were used to investigate risk factors associated with bovine brucellosis seropositivity. Serum samples were tested using the Rose Bengal test (RBT) and indirect enzyme linked immunosorbent assay (iELISA). Using a parallel interpretation, RBT and iELISA results showed that 10.3% (95% confidence interval (CI): 8.4, 12.4) of the cattle had antibodies against Brucella in our study area. The logistic regression analysis indicated that brucellosis seropositivity was associated with age and herd size. Cattle above 5 years of age were found to have a higher chance of being seropositive (odd ratio (OR)=2.8; 95% CI: 1.3, 6.4) compared to cattle under 3 years of age. Similarly, the odd of brucellosis seropositivity for herds with more than 100 cattle was 3.3 (95% CI: 1.2, 8.9) times higher compared to those with less than 50 cattle.

Bayesian estimation of the true prevalence, sensitivity and specificity of the Rose Bengal and indirect ELISA tests in the diagnosis of bovine brucellosis

Serology is the most convenient method for detecting brucellosis but the efficient use of such tests in disease control requires evaluation of diagnostic performance and discriminative ability. The objective of this study was to assess the performance of the Rose Bengal test (RBT) and an indirect ELISA (iELISA) in diagnosing brucellosis in 995 serum samples collected from cattle in the Ivory Coast between 2005 and 2009. A Bayesian approach was used to evaluate the two tests by estimating their sensitivities and specificities. The correlation-adjusted sensitivity of the iELISA was estimated to be 96.1% (credibility interval [CrI], 92.7-99.8), whereas that of the RBT was 54.9% (CrI, 23.5-95.1). High correlation-adjusted specificities were found for both tests (95.0%; [CrI, 91.1-99.6] for the iELISA and 97.7%; [CrI, 95.3-99.4] for the RBT, respectively). The true prevalence of brucellosis was estimated from the serum samples to be 4.6% (95%; [CrI, 0.6-9.5]). The level of agreement between the two tests was evaluated using indices of agreement (n=995). Good agreement was found for negative results (96.6%; confidence interval [CI], 95.7-97.4), a finding supported by an estimated significant correlation of 0.37 (95%; CI, 0.01-0.73) within the sera testing negative. Agreement was lower for sera testing positive (52.2% CI: 41.9-62.5). The findings highlight the importance of using these two tests in combination as part of any brucellosis control programme.

Economic burden of bovine trypanosomosis in three villages of Metekel zone, Northwest Ethiopia

The study was carried out to assess the economic burden of trypanosomosis in three villages of the Metekel zone in 2009. The disease was found to cause substantial economic losses through cattle mortality, drug purchase, and draft power loss of infected oxen. The farmers in the area were spending a significantly (p < 0.05) higher amount of money for the treatment of trypanosomosis than all other diseases combined. The overall mortality rate of cattle due to trypanosomosis was 4.4%. The mortality was significantly higher (p < 0.05) in an area where trypanosomosis prevalence was also higher. Many of the farmers prioritized losses of draft power as the most important impact of the disease. The overall prevalence of the disease was 12.1%. The disease burden was significantly (p < 0.05) higher in the rainy season than at other times of the year. In general, farmers had good knowledge on the signs and seasonality of trypanosomosis. Thus, tsetse suppression activities that involve the local community can be an important tool towards minimizing the economic burden of the disease in the area.

Methodology for assessing determinants of manure use in urban areas of Africa

The objectives of this study were to identify the major determinants (e.g. zootechnical and socio-economic parameters) of manure management practised by urban livestock keepers. Data were collected from four single-visit, multi-object surveys in three cities of Africa. The livestock keepers were classified either as ‘good user’ or ‘bad user’ of manure depending on how they use the manure. The results of this study indicate that the habit of manure utilization shows geographical differences. In general, livestock keepers engaged in agricultural activities are good manure users. Furthermore, manual workers, traders or the self-employed are better manure users than other professional groups. The manure utilization varies also in function of the livestock numbers. In Brazzaville, the habit of selling animals influenced manure management positively. Experience of keeping livestock before the civil war in Brazzaville was also a determining factor of manure use in the post-war urban livestock keeping in 2001. When designing policies to reduce the environmental effects of urban livestock keeping, the highlighted factors can assist city planners to understand how urban livestock keepers use manure. Using the non-parametric classification tree method CART, two approaches were used to select an optimal classification of ‘bad’ manure users: the ‘Cook and Goldman rule’ and the ‘Classification with different misclassification cost ratios’ method. The optimal tree was selected by using receiver operating characteristics curve information. This method can be useful in assessing other aspects of waste management.

Three Approaches for the Integrated Assessment of Urban Household Livestock Production Systems Cases from Sub-Saharan Africa

Urban household livestock production (UHLP) as a livelihood strategy is discussed with a focus on Sub-Saharan Africa. The paper is based on a literature study and two large-scale surveys (cities of Brazzaville and Ouagadougou). The results are discussed in relation to three theoretical concepts, that is, the Sustainable Urban Livelihood model, economic integration theory and non-linear system thinking. The first considers various assets, livelihood outcomes and constraints of UHLP rather than focusing on one aspect only. The second highlights three modes of economic integration, namely market exchange, redistribution and reciprocity. The third introduces notions of non-linearity to help explain how systems vary and repeat themselves at different scales. The paper shows the complexity of urban and peri-urban livestock production, which comprises a wide variety of animal species and production systems. UHLP has many interfaces and has to be considered within a broader urban–rural continuum. The paper concludes that the dynamics of urban livestock cannot be understood by looking at parts only. A narrow focus on the food value of urban livestock misses issues such as income and disease; looking only at public hygiene overlooks the essential role of urban livestock in making and keeping local communities ‘healthy’.

Effects of Livestock Import Bans Imposed by Saudi Arabia on Somaliland for Sanitary Reasons Related to Rift Valley Fever

Data were gathered from Berbera Port official records and Food and Agriculture Organization (FAO) food monitoring units (FSAU and FEWS), but mainly from interviews with 600 Somaliland livestock producers and 15 key exporters to assess the socioeconomic effects of the ban on livestock imports imposed on Somaliland following Rift Valley fever outbreaks. The study revealed that between February 1998 and December 2003, the Somaliland state government suffered significant losses of income – estimated at US