Prevalence and antimicrobial resistance pattern of Salmonella in animal feed produced in Namibia.

The occurrence of Salmonella is a global challenge in the public health and food production sectors. Our study investigated the prevalence, serovar and antimicrobial susceptibility of strains of Salmonella serovars isolated from animal feed (meat-and-bone and blood meal) samples from two commercial abattoirs in Namibia. A total of 650 samples (n=650) were examined for the presence of Salmonella.

Control of tick populations by spraying Metarhizium anisopliae conidia on cattle under field conditions.

Conidia of the entomopathogenic fungus, Metarhizium anisopliae, in oil/water formulation (1 × 10(8) conidia/ml) were sprayed at 3 weekly intervals on Rhipicephalus evertsi evertsi and Rhipicephalus (Boophilus) decoloratus ticks while feeding on Afrikana bulls grazing in paddocks for a period of 1 year. The fungus reduced the on-host tick populations by 83% 3 month after commencement of the experiment. The formulation by itself had only minimal effect on the tick population.

Protection of Metarhizium anisopliae conidia from ultra-violet radiation and their pathogenicity to Rhipicephalus evertsi evertsi ticks.

Metarhizium anisopliae conidia were formulated in water or in olive oil containing 3% commercial sunscreens (Everysun or E45 Sun Block 50) and exposed to an artificial UV source for up to 5 hours. Survival of conidia after 5 h of exposure to UV in oil formulation was 29% when protected with Everysun, 40% when protected with E45, and 4% in control. In comparison, survival of conidia formulated in water was 13% when protected with Everysun, 24% when protected with E45, and 0% in control.

Biological differences within Rhipicephalus appendiculatus Neumann (Acari: Ixodidae populations in Kenya.

Differences in biological parameters of Rhipicephalus appendiculatus Neumann, the brown ear tick, were investigated. They included engorgement weight of larvae, nymphs and females, fecundity, size of unfed females and mean larval and nymphal duration post-repletion on rabbits to completion of the moult. Ticks were collected from four geographically isolated zones in Kenya and from nymphs and females, size of unfed females and weight of egg batches per tick were noted (p < 0.

Performance of a prototype baited-trap in attracting and infecting the tick Amblyomma variegatum (Acari: Ixodidae) in field experiments.

Investigations were commenced to study the potential use of the fungi, Beauveria bassiana, Metarhizium anisopliae, and the attraction-aggregation-attachment pheromone (AAAP) for the control of Ambloyomma variegatum as an environmentally friendly technology. The objective of the study was to develop and test a device, which could be used for pheromone and carbon dioxide delivery and infection of ticks with the fungi in an attempt to control the tick populations in the vegetation. Using a pheromone-baited device treated with the fungi mixture, 79% of the ticks released were attracted and exposed to the fungi and of these, 78% died during incubation in the laboratory.

Effects of combining the fungi Beauveria bassiana and Metarhizium anisopliae on the mortality of the tick Amblyomma variegatum (ixodidae) in relation to seasonal changes.

The effect of formulation, fungal concentration, type and seasonal changes on the mortality of the tick Amblyomma variegatum was investigated. A previous study demonstrated high pathogenicity of strains of the fungi Beauveria bassiana and Metarhizium anisopliae against the ticks Rhipicephalus appendiculatus and Amblyomma variegatum (Kaaya et al. J Invertebr Pathol 1996; 67: 15-20).

Attraction of Amblyomma variegatum (ticks) to the attraction-aggregation-attachment-pheromone with or without carbon dioxide.

The responses of adult Amblyomma variegatum ticks released from various distances to different doses of the synthetic attraction-aggregation-attachment pheromone (AAAP) (made up of orthonitrophenol, methyl salicylate and nonanoic acid in paraffin oil), dispensed from the center of circular field plots, were studied in the presence or absence of elevated levels of CO2. Up to 90% of the ticks released were attracted to the pheromone source in the presence of CO2 within 3h. CO2 alone was unattractive, similar to previous findings in Zimbabwe, but unlike results from a Caribbean A.

The potential for antitick plants as components of an integrated tick control strategy.

Extracts from various African plants have been shown to possess strong acaricidal and/or tick repellent properties. Some of the plant extracts are capable of reducing tick feeding, molting, fecundity, and viability of eggs. Pasture grasses capable of repelling, trapping, and killing ticks have also been reported.

Laboratory and field evaluation of entomogenous fungi for tick control.

Aqueous and oil-based formulations of two entomogenous fungi, Beauveria bassiana and Metarhizium anisopliae were tested for their efficacy against the three major species of African ticks; namely, Amblyomma variegatum, Rhipicephalus apendiculatus, and Boophilus decoloratus. Both fungal species and formulations were observed to induce high mortalities, especially in the larvae. The oil-based formulation was found to be more effective than the aqueous formulation.

Laboratory evaluation of pathogenicity of entomogenous nematodes to African tick species.

Five strains of entomogenous nematodes, Steinernema carpocapsae strains DD, Mexican, SR, and Heterorhabditis bacteriophora strains 1S5 and HP88, were tested for their pathogenicity to various developmental stages of five African tick species namely; Rhipicephalus appendiculatus, R. evertsi, Amblyomma variegatum, A. gemma, and Boophilus decoloratus.

Development, reproductive capacity and survival of Amblyomma variegatum and Boophilus decoloratus in relation to host resistance and climatic factors under field conditions.

To determine the developmental periods, fecundity and survival of Amblyomma variegatum and Boophilus decoloratus and the effect of host resistance, a study was carried out in the field at Abernossa ranch in Ethiopia using three breeds of cattle: Arssi, Boran and Boran x Friesian crossbreed. The investigation took place between October 1991 and September 1992. The developmental periods of both tick species were recorded.

The impact of Ixodiphagus hookeri, a tick parasitoid, on Amblyomma variegatum (Acari: Ixodidae) in a field trial in Kenya.

In an experiment to investigate the effect of the tick parasitoid, Ixodiphagus hookeri, on tick numbers on cattle, 150000 parasitoids were released over a period of 1 year in a field where ten cattle infested with multiple tick species were kept. Amblyomma variegatum was reduced from 44 to two ticks per animal while Rhipicephalus appendiculatus increased over the time of parasitoid release. During the time of release 51% of the nymphs of A.

Acquisition of resistance to the tick Amblyomma variegatum in Boran cattle, Bos indicus and the effects of Trypanosoma congolense and Babesia bigemina on host resistance.

Resistance was induced in cattle to the tick Amblyomma variegatum by five consecutive infestations with nymphs and adults. Using the principal component analysis (PCA), it was found that percentage of adults engorged, percentage of adults which died, percentage of nymphs which engorged, percentage of nymphs which moulted and percentage of nymphs which died, were the main indicators of resistance against A. variegatum.

Comparison of resistance in three breeds of cattle against African ixodid ticks.

Tick resistance in three breeds of cattle, two indigenous breeds (Arssi and Boran) and one Boran x Friesian cross-bread, were compared following natural tick infestations at Abernossa ranch in Ethiopia. The local Arssi breed was found to have the highest tick resistance, followed by the Boran breed, whereas the Boran x Friesian was the least resistant. Over a period of 12 months, from October 1991 to September 1992, a total of 32,897 ticks composed of four genera were collected from the animals.

Pulmonary function results in asbestos factory workers.

The pattern of lung function was assessed in a group of 159 male employees of the Dar es Salaam asbestos factory. The results were compared with a control group (N= 180) of age and sex matched from the same area but not exposed to asbestos. The mean age were 32.

Prospects for biological control of livestock ticks, Rhipicephalus appendiculatus and Amblyomma variegatum, using the entomogenous fungi Beauveria bassiana and Metarhizium anisopliae.

Both Beauveria bassiana and Metarhizium anisopliae induced approximately 30% mortalities in adult Rhipicephalus appendiculatus feeding on rabbits while M. anisopliae induced a mortality of 37% in adult Amblyomma variegatum. Both fungal species induced reductions in engorgement weights, fecundity, and egg hatchability in adult A.

Repellence of the tick Rhipicephalus appendiculatus by the grass Melinis minutiflora.

In a study to develop anti-tick pastures, the climbing behaviour of Rhipicephalus appendiculatus on Melinis minutiflora (molasses grass) was investigated. Experiments were done with cut green stems of grass, grass dried in the shade, grass dried in sunshine, grass washed in solvent and grass growing in a study plot. In all cases a common pasture grass, Pennisetum clandestinum (Kikuyu grass), was used as control.

Biocontrol potential of the entomogenous fungi Beauveria bassiana and Metarhizium anisopliae for tsetse flies (Glossina spp.) at developmental sites.

Spores of two entomogenous fungi, Beauveria bassiana and Metarhizium anisopliae, were mixed with sterile sand at two different concentrations (1.0 and 0.5 g/liter) and larvae of tsetse flies Glossina morsitans morsitans allowed to pupate in it, simulating field larviposition sites.

Normal peak expiratory flow in healthy adult male and female subjects.

Peak expiratory flows (PEF) were measured in 830 and 270 healthy male and female subjects respectively using Autospiro model AS-500 (Minato, Japan) fitted with a heated pneumotachograph. All measurements were made in the standing position. Male subjects gave significantly larger PEF values than female subjects (P < 0.

Predation of free-living engorged female Rhipicephalus appendiculatus.

In experiments done over a period of 1 1/2 years using engorged female Rhipicephalus appendiculatus tethered in a grass plot, 42% predation was observed in long grass (40-60 cm), and 36% in short grass (6-10 cm). Deaths due to environmental factors were 4.8% and 6.

Mortality in adult tsetse, Glossina morsitans morsitans, caused by entomopathogenic bacteria.

Mortality in adult tsetse, Glossina morsitans morsitans, caused by Pseudomonas aeruginosa, Serratia marcescens, Bacillus sphaericus, Bacillus cereus, Bacillus thuringiensis H-14, B. thuringiensis 1, B. thuringiensis 5, B.

Comparative trypanotolerance of the small east African breed of goats from different localities to Trypanosoma congolense infection.

Differences in susceptibility of the Small East African breed of goats to an experimental Trypanosoma congolense infection were investigated. The goats were obtained from different areas of East Africa, Morogoro and Arusha (Tanzania), Imbo and Lambwe Valley (Kenya). Morogoro goats were found to be more tolerant, followed by Arusha, Lambwe Valley and Imbo goats, in that order.

Glossina morsitans morsitans: mortalities caused in adults by experimental infection with entomopathogenic fungi.

Various strains of the entomopathogenic fungi: Beauveria bassiana, Metarhizium anisopliae, Paecilomyces fumosoroseus and P. farinosus were found to be pathogenic for adult tsetse, Glossina morsitans morsitans but B. bassiana and M.

Trypanosome-induced ovarian dysfunction. Evidence of higher residual fertility in trypanotolerant small East African goats.

Changes in the length of oestrous cycles, plasma progesterone and oestradiol-17 beta levels were monitored for 6 months in Trypanosoma congolense-infected normocyclic small East African goats obtained from three tsetse-endemic areas and one tsetse-free area of East Africa. Irregular oestrous cycles were observed in all infected goats, before cessation at the second cycle post-infection in the more susceptible and fourth cycle in the more resistant goat groups. A significant decline in the progesterone and oestradiol-17 beta parameters were observed.

Depression of ovarian function and plasma progesterone and estradiol-17 beta in female goats chronically infected with Trypanosoma congolense.

Adult normocyclic female goats experimentally infected with Trypanosoma congolense developed irregular and shorter estrous cycles before complete cessation at the fourth cycle post-infection. This was followed within a month by a decline in the mean plasma progesterone and estradiol-17 beta levels. The peak luteal progesterone as well as pre-ovulatory estradiol-17 beta level declined progressively from the second to the fourth cycle post-infection.