A new species of Isospora (Apicomplexa: Eimeriidae) from the greenfinch Carduelis chloris (Passeriformes: Fringillidae)

A new species of isosporan (Apicomplexa: Eimeriidae) is reported from the greenfinch, Carduelis chloris (Passeriformes: Fringillidae), in England. Oocysts of Isospora daszaki n.sp. are spherical to subspherical, 18.8 × 20.3 (16.8-22.4 × 16.8-25.2) μm, with a shape index (length/width) of 1.08 (1.07-1.1). Micropyle, polar granules and oocyst residuum are absent. Sporocysts are 9.4 × 14.8 (8.4-11.2 × 12.6-18.2) μm, a shape index of 1.6, with Stieda and substieda bodies. Gamogony was seen in the ileum, and merozoites were present in blood lymphocytes.

Possible ecology and epidemiology of medically important mosquito-borne arboviruses in Great Britain

Nine different arboviruses are known to be transmitted by, or associated with, mosquitoes in Europe, and several (West Nile, Sindbis and Tahyna viruses) are reported to cause outbreaks of human disease. Although there have been no reported human cases in Great Britain (GB), there have been no published in-depth serological surveys for evidence of human infection. This paper investigates the ecological and entomological factors that could influence or restrict transmission of these viruses in GB, suggesting that in addition to West Nile virus, Sindbis and Tahyna viruses could exist in enzootic cycles, and that certain ecological factors could facilitate transmission to humans. However, the level of transmission is likely to be lower than in endemic foci elsewhere in Europe due to key ecological differences related to spatial and temporal dynamics of putative mosquito vectors and presence of key reservoir hosts. Knowledge of the potential GB-specific disease ecology can aid assessments of risk from mosquito-borne arboviruses.

Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors

West Nile virus (WNV) transmitted by mosquitoes (Diptera: Culicidae) infects various vertebrates, being pathogenic for birds, horses and humans. After its discovery in tropical Africa, sporadic outbreaks of WNV occurred during recent decades in Eurasia, but not the British Isles. WNV reached New York in 1999 and spread to California by 2003, causing widespread outbreaks of West Nile encephalitis across North America, transmitted by many species of mosquitoes, mainly Culex spp. The periodic reappearance of WNV in parts of continental Europe (from southern France to Romania) gives rise to concern over the possibility of WNV invading the British Isles. The British Isles have about 30 endemic mosquito species, several with seasonal abundance and other eco-behavioural characteristics predisposing them to serve as potential WNV bridge vectors from birds to humans. These include: the predominantly ornithophilic Culex pipiens L. and its anthropophilic biotype molestus Forskal; tree-hole adapted Anopheles plumbeus Stephens; saltmarsh-adapted Ochlerotatus caspius Pallas, Oc. detritus Haliday and Oc. dorsalis (Meigen); Coquillettidia richiardii Ficalbi, Culiseta annulata Schrank and Cs. morsitans (Theobald) from vegetated freshwater pools; Aedes cinereus Meigen, Oc. cantans Meigen and Oc. punctor Kirby from seasonal woodland pools. Those underlined have been found carrying WNV in other countries (12 species), including the rarer British species Aedes vexans (Meigen), Culex europaeus Ramos et al., Cx. modestus Ficalbi and Oc. sticticus (Meigen) as well as the Anopheles maculipennis Meigen complex (mainly An. atroparvus van Thiel and An. messeae Falleroni in Britain). Those implicated as key vectors of WNV in Europe are printed bold (four species). So far there is no proof of any arbovirus transmission by mosquitoes in the British Isles, although antibodies to Sindbis, Tahyna, Usutu and West Nile viruses have been detected in British birds. Neighbouring European countries have enzootic WNV and human infections transmitted by mosquito species that are present in the British Isles. However, except for localized urban infestations of Cx. pipiens biotype molestus that can be readily eliminated, there appear to be few situations in the British Isles where humans and livestock are exposed to sustained risks of exposure to potential WNV vectors. Monitoring of mosquitoes and arbovirus surveillance are required to guard the British Isles against WNV outbreaks and introduction of more anthropophilic mosquitoes such as Stegomyia albopicta (Skuse) and Ochlerotatus japonicus (Theobald) that have recently invaded Europe, since they transmit arboviruses elsewhere.

Prevalence of intestinal parasites in feral cats in some urban areas of England

Of 92 feral cats necropsied from the London and Sheffield areas, 49 (53.3%) were infected with Toxocara cati, 32 (34.8%) with Dipylidium caninum, 11 (12.0%) with Taenia taeniaeformis and 1 (1.1%) with Toxascaris leonina. Isospora felis was seen in 3 (4.3%) of 69 samples of faeces. Twenty-two cats (23.9%) were simultaneously infected with 2 helminth species.

Prevalence of intestinal parasites in domestic cats from the London area

The prevalence of intestinal parasites in domestic cats from the London area was surveyed over an 18-month period by microscopic examination of faecal samples. Of the 947 cats examined 11.5 per cent were infected with Toxocara cati, 1.9 per cent with Isospora felis, 1.2 per cent with Dipylidium caninum, 1.2 per cent with Taenia taeniaeformis, 0.8 per cent with I rivolta and 0.2 per cent with Toxascaris leonina.

Larvae of the British Metastriata (Ixodoidea: Ixodidae)

Detailed descriptions are given of the larvae of the three species of British metastriatan ticks, with particular reference to the arrangement and dimensions of setae.

Larvae of the Ixodes ricinus complex of species

An account is given of the morphological characteristics of larvae of four species of the Ixodes ricinus complex, namely I. ricinus, I. persulcatus, I. pacificus and I. nipponensis. Particular reference is made to chaetotaxy and its importance in differentiating larvae of closely related species is emphasized.

We are grateful to Dr G. Owen Evans for discussion on matters on chaetotaxy.

The quantity of blood imbibed by Hyalomma anatolicum anatolicum Koch, 1844 (Ixodoidea, Ixodidae)

1. The weight of blood ingested by all stages of H. anatolicum anatolicum has been determined and from the results a direct relationship appears to exist between the weights of replete adults and their blood content. In engorged nymphs the relationship was subject to some variations, while in fully fed larvae no such correlation was apparent, indicating the ingestion of a large proportion of extravascular fluids.

2. It was found that all instars concentrate the imbibed blood by the elimination of water. In larvae the concentration is by a factor of at least 5·25, in nymphs 3·4, in females 2·1 and in males 1·4.

3. A correlation was found between the external colour of fully engorged larvae and the quantity of blood imbibed.

I wish to thank Dr R. P. Chaudhuri for providing the original specimens of H. anatolicum anatolicum from which the culture was started, and Professor Don. R. Arthur for reading the manuscript and for his advice and assistance.

The life-history of Hyalomma anatolicum anatolicum Koch, 1844 (Ixodoidea, Ixodidae) under laboratory conditions

The durations of the various phases of the life-history of the ixodid tickH. anatolicum anatolicumare described with particular reference to the modifying influence of temperature and relative humidity. An increase in the ambient temperature was found to decrease the length of the feeding, preoviposition, oviposition, larval and nymphal moulting periods and the egg-incubation period. The effect of change in relative humidity was less marked, the only significant effect being on the oviposition period which was protracted when the relative humidity was increased.

Daily percentage water loss and longevity were found to be more or less inversely proportional. Thus at high temperatures and low relative humidities a large percentage of water was lost daily with consequent reduced life span.

I wish to thank Dr R. P. Chaudhuri for providing me with the specimens ofH. anatolicum anatolicumfrom which the culture was started, and Professor D. R. Arthur for his advice and assistance. I am also grateful to the Science Research Council for the provision of a research grant.

Ixodes pacificus Cooley and Kohls, 1943: its life-histor and occurrence

The life-history of I. pacificus when fed on guinea-pigs under laboratory conditions is described. Feeding of the female proceeds for 10–11 days. Between 120 and 191 mg of concentrated food is found in the female's gut on detaching from this host, and this is directly related to the unfed body weight of the tick.

The egg-laying pattern, in general, shows an initial peak, after which the number of eggs tails off, the whole process lasting approximately 33–40 days. The number of eggs laid by females varies between 790 and 1300. The preoviposition period is about 11–16 days.

Larvae hatch in about 53–55 days, and their feeding time ranges from 4 to 9 days, although in the present experiments larvae emerging from early laid eggs took about 10 days to complete engorgements.

Moulting of larvae to nymphs at 90% R.H. took 37–38 days, and nymphs fed for 7–11 days, with most becoming replete on the ninth.

Very few females emerged from these nymphs, and those that did emerged in just over 30 days. The reasons for this are not clear. No diapause appeared to be necessary to complete the life-cycle, and with due allowance for hardening of the mouthparts the life-history of one generation was about 7 months. Females died within 3 or 4 months if hosts were not available.

From the literature and from hitherto unpublished records some 55 vertebrates have been implicated as hosts to I. pacificus; these hosts include a wide range of mammals, six species of birds and possibly nine species of lizards.

The species has been listed from British Columbia and from five western states of U.S.A. The need for more intensive ecological work on this species is emphasized.

We are indebted to Glen M. Kohls, J. D. Gregson and D. E. Johnstone for permission to use unpublished records from their respective institutions. One of us (D.R.A) is also indebted to the Wellcome Trustees for financial assistance to visit Canada during the preliminary stages of the work.

Oviposition in Hyalomma anatolicum anatolicum (Koch, 1844) (Ixodoidea: Ixodidae)

For the tick Hyalomma anatolicum anatolicum, at constant temperature and humidity, the pattern of oviposition is constant, and consists of a peak period, usually after 2–3 days, followed by a gradual decline.

Oviposition proceeds more rapidly in constant darkness than in continuous light.

With increased temperature the oviposition period is decreased, but with increased humidity the period is extended.

The largest eggs are laid from 0 to 48 h after the peak of egg production, and no correlation has been observed between female size and egg size.

The number of eggs produced by a tick is directly proportional to its engorged weight, and since the engorged female weight is a direct reflexion of its unfed weight, the number of eggs laid is directly dependent on the size of the unfed female.

Guinea-pigs show partial immune response to adults of H. anatolicum anatolicum when the ticks are fed on them repeatedly. This minimizes the amount of nutrients imbibed and accordingly egg-laying potential is not realized.

The material on which this study was made was presented to us by Dr R. P. Chaudhuri, and we gratefully acknowledge his kindness.