Bartonella species and their ectoparasites: selective host adaptation or strain selection between the vector and the mammalian host?

A wide range of blood-sucking arthropods have either been confirmed or are suspected as important vectors in Bartonella transmission to mammals, including humans. Overall, it appears that the diversity of Bartonella species DNA identified in ectoparasites is much broader than the species detected in their mammalian hosts, suggesting a mechanism of adaptation of Bartonella species to their host-vector ecosystem. However, these mechanisms leading to the fitness between the vectors and their hosts still need to be investigated.     

Emerging parasitic diseases of sheep

There have been changes in the emergence and inability to control of a number of sheep parasitic infections over the last decade. This review focuses on the more globally important sheep parasites, whose reported changes in epidemiology, occurrence or failure to control are becoming increasingly evident. One of the main perceived driving forces is climate change, which can have profound effects on parasite epidemiology, especially for those parasitic diseases where weather has a direct effect on the development of free-living stages. The emergence of anthelmintic-resistant strains of parasitic nematodes and the increasing reliance placed on anthelmintics for their control, can exert profound changes on the epidemiology of those nematodes causing parasitic gastroenteritis. As a consequence, the effectiveness of existing control strategies presents a major threat to sheep production in many areas around the world. The incidence of the liver fluke, Fasciola hepatica, is inextricably linked to high rainfall and is particularly prevalent in high rainfall years. Over the last few decades, there have also been increasing reports of other fluke associated diseases, such as dicroceliosis and paramphistomosis, in a number of western European countries, possibly introduced through animal movements, and able to establish with changing climates. External parasite infections, such as myiasis, can cause significant economic loss and presents as a major welfare problem. The range of elevated temperatures predicted by current climate change scenarios, result in an elongated blowfly season with earlier spring emergence and a higher cumulative incidence of fly strike. Additionally, legislative decisions leading to enforced changes in pesticide usage and choices have resulted in increased reports and spread of ectoparasitic infections, particularly mite, lice and tick infestations in sheep. Factors, such as dip disposal and associated environmental concerns, and, perhaps more importantly, product availability have led to a move away from more traditional methods of pesticide application, particularly dipping, to the use of injectable endectocides. This has coincided with increased reports of sheep scab and lice infestations in some countries. Reduction in the use of organophosphate dips appears to have to some extent contributed to reported increased populations of ticks and tick activity, a consequence of which is not only of significance to sheep, but also many other hosts, including increased human zoonotic risks.     

Prevalence of parasites of the local scavenging chickens in a selected semi-arid zone of Eastern Kenya

A study to identify and estimate the prevalence of parasites of local chickens in a semi arid area of Kenya was conducted between March 2005 and August 2006. Three hundred and sixty (360) local chickens purchased from Yathui division of Machakos were examined. Of those, 93.3% had helminths. Nematodes were recovered in 268 (74.4%) chickens whereas 245 (68.1%) had cestodes. Tetrameres americana (37.7%), Ascaridia galli (33.3%) and Heterakis gallinarum (22.8%) were the most important nematode species identified. Raillietina echinobothrida (33.3%) and Davainea proglottina (19.4%) were the two most important cestode species identified. Two coccidia species, namely Eimeria necatrix (6.7%) and E. tenella (16.7%) were isolated and identified as per location in the digestive system. Important ecto-parasites identified included Echidnophaga gallinacea (76.7%), Menacanthus stramineus (79.4%) and Dermanyssus gallinae (60.0%). Endo-parasites (helminths and coccidia) occurred in significantly (p < 0.05) higher frequencies during the wet season than during the dry season. On the contrary, ecto-parasites were significantly (p < 0.05) more fequent during the dry season. Male chickens generally exhibited increased odds for the occurrence of parasites than female birds. Further investigations are required to establish a plausible explanation for this. Overall, parasitism was a big constraint to chicken productivity in the study area. Urgent integrated parasite control approaches should be initiated to address parasitism in chickens in the Yathui cluster.     

Farmers'' opinions on welfare, health and production practices in extensive hill sheep flocks in Great Britain

Despite large numbers of hill sheep reared in the UK, little is known about how hill farmers react to health challenges in their flocks. This paper addresses this lack of knowledge of sheep health management practices and presents farmers' opinions and concerns, particularly regarding ectoparasite control. Focus groups and interviews with UK hill sheep farmers were carried out to collect information on management practices, health concerns, in addition to incidence and impacts of six major ectoparasites (ticks, lice, sheep scab mite, blowfly, keds and headfly), to determine how they viewed the effects of ectoparasites and their control on production practices.

We conclude that despite variations between hill sheep farm conditions and levels of input, similar health concerns and ectoparasite issues were found across different hill sheep farming areas of the UK. Farm labour was also an important issue and most farmers would prefer more labour to be available to effectively manage ectoparasites in their flocks. Finally, there was variation in farmers' opinions of the impact of ectoparasite species on welfare and productivity. This variation in opinion can be related to a trend in their past experience of ectoparasites, but no relationships were found with the animal health treatments farmers use, the number of animals in their flock or variation in the type of grazing land available.     

In vivo and in vitro treatments against Sparicotyle chrysophrii (Monogenea: Microcotylidae) parasitizing the gills of gilthead sea bream (Sparus aurata L.)

The effect of in vitro and in vivo treatments against Sparicotyle chrysophrii, a microcotylid parasite of gilthead sea bream (Sparus aurata L.), was studied. In vitro chemical treatments were targeted to eggs, oncomiracidia and adults, and were tested both as disinfectants and therapeutics for infected animals. The compounds were: distilled water, formalin, limoseptic ®, hydrogen peroxide, chlorine, and praziquantel (PZQ). Larvae were sensitive to all the treatments, but adults were more resistant, as chlorine (60 ppm - 1 h), hydrogen peroxide (100 ppm - 30 min) and PZQ (50 ppm - 30 min) produced only 10% mortality. All adults were killed only with distilled water, limoseptic (0.1% - 5 min), formalin (300 ppm - 30 min), or hydrogen peroxide (200 ppm - 30 min). Eggs were the most resistant stage, as only 30 min in limoseptic (0.1% in distilled water) or in formalin (300 ppm) prevented hatching. PZQ was used in vivo either as a curative or preventive treatment. The highest dose tested (400 mg kg^− 1 BW; effective dose 116.3 mg kg^− 1 BW due to palatability problems leading to 45% reduction in host food intake) did not significantly decrease prevalence of infection when given for 6 consecutive days. A lower dose (200 mg kg^− 1 BW) (effective dose 158.1 mg kg^− 1 BW) was rejected to a lower degree and decreased the prevalence of infection from 90% to 40%. When a lower dose (40 mg kg^− 1 BW) was administered for longer periods (20 days), food intake was reduced slightly, but the infection did not decrease significantly. The oral intubation with PZQ (200 mg kg^− 1 BW) once a week for 4 weeks did not prevent the infection of fish by cohabitation. However, a significant reduction in the abundance of the parasite was registered. In view of the results, recommendations for fish treatment and disinfection of aquaculture facilities are discussed.     

Disease control through fertility control: Secondary benefits of animal birth control in Indian street dogs

We sought to (1) survey sexually intact street dogs for a wide range of diseases in three cities in Rajasthan, India and (2) evaluate links between the health of non-treated dogs and both the presence and duration of animal birth control (ABC) programs. ABC regimes sterilize and vaccinate stray dogs in an attempt to control their population and the spread of rabies. They are commonly suggested to improve the health of those dogs they serve, but here we provide evidence that these benefits also extend to untreated dogs in the community.