Distribution of Rhipicephalus (Boophilus) microplus and Rhipicephalus (Boophilus) annulatus (Acari: Ixodidae) infestations detected in the United States along the Texas/Mexico border

Species identification and global positioning system coordinates of infestations of cattle fever ticks, Rhipicephalus (Boophilus) annulatus (Say) and Rhipicephalus (Boophilus) microplus (Canestrini), were determined for 790 specimens submitted to the National Veterinary Services Laboratory between 1 October 1999 and 30 September 2010. Cattle fever tick specimens obtained by personnel of the United States Department of Agriculture-Animal and Plant Health Inspection Service-Cattle Fever Tick Eradication Program from infested cattle and wildlife along the Texas/ Mexico border were submitted for identification, as required by the program. A geographic information system database was developed that incorporates location, collection, and infestation records. Submitted ticks came from 11 Texas counties and were comprised of 19.5% R. (B.) annulatus and 80.5% R. (B.) microplus. Maps produced from this study locate and define the parapatric boundary between R. (B.) annulatus and R. (B.) microplus.

Impact of high-concentrate feeding and low ruminal pH on methanogens and protozoa in the rumen of dairy cows

Non-lactating dairy cattle were transitioned to a high-concentrate diet to investigate the effect of ruminal pH suppression, commonly found in dairy cattle, on the density, diversity, and community structure of rumen methanogens, as well as the density of rumen protozoa. Four ruminally cannulated cows were fed a hay diet and transitioned to a 65% grain and 35% hay diet. The cattle were maintained on an high-concentrate diet for 3 weeks before the transition back to an hay diet, which was fed for an additional 3 weeks. Rumen fluid and solids and fecal samples were obtained prior to feeding during weeks 0 (hay), 1, and 3 (high-concentrate), and 4 and 6 (hay). Subacute ruminal acidosis was induced during week 1. During week 3 of the experiment, there was a significant increase in the number of protozoa present in the rumen fluid (P=0.049) and rumen solids (P=0.004), and a significant reduction in protozoa in the rumen fluid in week 6 (P=0.003). No significant effect of diet on density of rumen methanogens was found in any samples, as determined by real-time PCR. Clone libraries were constructed for weeks 0, 3, and 6, and the methanogen diversity of week 3 was found to differ from week 6. Week 3 was also found to have a significantly altered methanogen community structure, compared to the other weeks. Twenty-two unique 16S rRNA phylotypes were identified, three of which were found only during high-concentrate feeding, three were found during both phases of hay feeding, and seven were found in all three clone libraries. The genus Methanobrevibacter comprised 99% of the clones present. The rumen fluid at weeks 0, 3, and 6 of all the animals was found to contain a type A protozoal population. Ultimately, high-concentrate feeding did not significantly affect the density of rumen methanogens, but did alter methanogen diversity and community structure, as well as protozoal density within the rumen of nonlactating dairy cattle. Therefore, it may be necessary to monitor the rumen methanogen and protozoal communities of dairy cattle susceptible to depressed pH when methane abatement strategies are being investigated.

[An investigation on malaria vectors in western part of China-Myanmar border]

OBJECTIVE

To reveal the distribution and composition of malaria-transmitting vectors on the western part of China-Myanmar border.

METHODS

An entomological survey of malaria vectors was carried out in six villages of Yingjiang County and Xidong County on China-Myanmar border between August and September, 2008. Mosquitoes in human dwellings and cattle sheds were collected by overnight trapping with ovitrap light. The mosquitoes were firstly identified morphologically, and then Anopheles minimus A and C, An. aconitus, and An. jeyporiensis were identified by using multiplex PCR. Some mosquitoes were selected to extract the total genomic DNA, and detect sporozoites by nested PCR.

RESULTS

A total of 4571 mosquitoes were captured with 54.32% (2483/4571) of anopheline mosquitoes. There was significant difference in Anopheles species composition in human dwellings and cattle sheda The main species in human dwellings were An. kochi, An. minimus, and An. sinensis, while the principal species in cattle sheds consist of An. kochi (223), An. annularis (184), An. vagus (131), and An jeyporiensis (129). Furthermore, the composition in human dwellings of villages with and without cattle was significantly different. An. minimus (260) and An. kochi (49) werethe most important species in villages with cattle, whereas An. kochi (481) and An. sinensis (124) were the key species in villages without cattle. A total of 1075 mosquitoes were examined for sporozoites and 9 mosquitoes were found to be infected. Only three species, Le. An. minimus (7/408), An aconiaus (1/125) and An. pseudowillmori (1/101) were infected with malaria parasite. All sporozoites were identified as Plasmodium falcipoarum by sequencing, the target fragment was 204 bp.

CONCLUSION

The species composition of mosquitoes is complex in the study sites on the western part of China-Myanmar border, and An. minimus is the major malaria vector. Additionally, An. aconitus and An.pseudowillmori are also confirmed as potential malaria vector in this area.

Evaluation of mammalian and intermediate host surveillance methods for detecting schistosomiasis reemergence in southwest China

Background

Schistosomiasis has reemerged in China, threatening schistosomiasis elimination efforts. Surveillance methods that can identify locations where schistosomiasis has reemerged are needed to prevent the further spread of infections.

Methods and Principal Findings

We tested humans, cows, water buffalo and the intermediate host snail, Oncomelania hupensis, for Schistosoma japonicum infection, assessed snail densities and extracted regional surveillance records in areas where schistosomiasis reemerged in Sichuan province. We then evaluated the ability of surveillance methods to identify villages where human infections were present. Human infections were detected in 35 of the 53 villages surveyed (infection prevalence: 0 to 43%), including 17 of 28 villages with no prior evidence of reemergence. Bovine infections were detected in 23 villages (infection prevalence: 0 to 65%) and snail infections in one village. Two common surveillance methods, acute schistosomiasis case reports and surveys for S. japonicum-infected snails, grossly underestimated the number of villages where human infections were present (sensitivity 1% and 3%, respectively). Screening bovines for S. japonicum and surveys for the presence of O. hupensis had modest sensitivity (59% and 69% respectively) and specificity (67% and 44%, respectively). Older adults and bovine owners were at elevated risk of infection. Testing only these high-risk human populations yielded sensitivities of 77% and 71%, respectively.

Conclusions

Human and bovine schistosomiasis were widespread in regions where schistosomiasis had reemerged but acute schistosomiasis and S. japonicum-infected snails were rare and, therefore, poor surveillance targets. Until more efficient, sensitive surveillance strategies are developed, direct, targeted parasitological testing of high-risk human populations should be considered to monitor for schistosomiasis reemergence.

Schistosomiasis has reemerged in China in regions where it was previously controlled. As reductions in schistosomiasis, a water-born parasitic infection, prompt consideration of schistosomiasis elimination, surveillance strategies that can signal reemergence and prevent further lapses in control are needed. We examined the distribution of Schistosoma japonicum, the species that causes schistosomiasis in China, in 53 villages. The villages were located in regions of Sichuan province where schistosomiasis reemergence had been documented by public health authorities. We tested three key reservoirs, humans, cows and water buffalo, and freshwater snails for S. japonicum infection in an effort to identify high-risk populations and evaluate their ability to signal reemergence. Human and bovine infections were common, detected in 35 villages and 23 villages, respectively, but infected snails were rare, found in only one village. Two commonly used surveillance methods, hospital reports of acute schistosomiasis and surveys for S. japonicum-infected snails, grossly underestimated the number of villages where human infections were present. Schistosomiasis was widespread in the region we studied, highlighting the danger reemergence poses to disease elimination programs. Surveillance systems that monitor high-risk populations such as older adults or bovine owners should be considered to promote detection of reemergence.

Effects of passages through a suitable host of the fungus, Metarhizium anisopliae, on the virulence of acaricide-susceptible and resistant strains of the tick, Rhipicephalus microplus

The aim of this work was to assess the virulence of strain M379 of the fungus, Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) after different passages through a suitable host and at different concentrations for the control of both acaricide-susceptible and resistant strains of the tick, Rhipicephalus (formerly Boophilus) microplus Canestrini (Ixodida:Ixodidae) in vitro. The highest value of LC50 for the susceptible strain corresponded to zero passage with 7.68 × 107 conidia/ml followed by the fourth passage with 2.68 × 107, which reduced 2.87-fold the lethal concentration. When comparing LC50 values of the fourth vs. the seventh passage (2.59 × 105 conidia/ml), the lethal concentration was reduced 103.47-fold by the seventh passage. In addition, in the resistant strain the LC50 highest value corresponded to zero passage with 4.95 × 107 conidia/ml followed by the fourth passage with 7.86 × 106, which reduced 6.30-fold the lethal concentration. When comparing LC50 values of the fourth vs. the seventh passage (1.04 × 105 conidia/ml) in the resistant strain, the lethal concentration was reduced 75.58-fold by the seventh passage. These results suggest that the number of passages on M. anisopliae through a suitable host increased its virulence on both R. microplus strains. When comparing LC50 of the zero passage through a suitable host of both acaricide-susceptible and resistant strains, the highest LC50 values corresponded to the susceptible strain with 7.68 × 107 conidia/ml followed by the resistant one with 4.95 × 107, showing that on the resistant strain the lethal concentration is reduced by 1.55-fold. When comparing the fourth passage, the highest values of LC50 corresponded to the susceptible strain with 2.68 x 107 conidia/ml followed by the resistant one with 7.86 × 106 conidia/ml, showing for the resistant strain a 3.41-fold reduced lethal concentration. Moreover, when comparing the seventh passages, the highest values of LC50 corresponded to the susceptible strain with 2.59 × 105 followed by the resistant with 1.04 × 105 conidia/ml, revealing for the resistant strain a 2.49-fold reduced lethal concentration. These results suggest that the resistant strain needs a lower concentration of conidia than the susceptible strain. In this case, the acaricide-resistant strain is more susceptible to M. anisopliae of zero- and seven-passage strains.

Host blood meal identification by multiplex polymerase chain reaction for dispersal evidence of stable flies (Diptera:Muscidae) between livestock facilities

A species-specific multiplex polymerase chain reaction targeting the cytochrome b gene of cattle, horses, humans, and dogs was developed to determine the blood meal sources of stable flies, Stomoxys calcitrans (L.), collected from Florida equine facilities. Of 595 presumptive blood-fed stable flies analyzed, successful host amplification was obtained in 350, for a field host-detection efficiency of 58.8%. The majority of analyzed stable flies had fed on cattle (64.6%), followed by horses (24.3%), humans (9.5%), and dogs (1.6%). A survey of animal-enclosed pastures occurring within 3 km of stable fly collection sites revealed that the nearest cattle were between 0.8 and 1.5 km from the four horse farm sampling sites. Cattle-feeding frequencies were greater on farms where cattle were located at distances of 0.8 km, suggesting that between farm differences in host-feeding frequency is related to the number of and distance from a particular host type. Time course evaluations of previously laboratory-fed stable flies demonstrated that host-detection efficiency with this system was 100, 50, and 0% when flies were evaluated at 16, 24, and 48 h postblood feeding, respectively. The results of this study suggest short-term stable fly dispersal of up to 1.5 km in a 48-h time period. The implications of these findings are discussed.

Repellency of a wax-based catnip-oil formulation against stable flies

Stable flies, Stomoxys calcitrans (L.), are one of the most serious livestock pests, which cause significant economic loss in the cattle industry. Current practices for managing stable flies are limited to costly sanitation techniques and unsustainable insecticide applications. The present study reports the initial efforts using catnip essential oil as a spatial repellent and the results of field trials using a wax-based formulation to repel stable flies in the cattle feedlot. Electroantennograms showed that catnip oil and its ingredient compounds elicit significant antennal responses from both sexes of stable flies. Catnip oil and ZE- and EZ-nepetalactone showed repellent activity in a single cage olfactormeter study. No behavioral activity was observed from another ingredient compound, caryophyllene. A laboratory dispersal bioassay also showed that stable flies avoided areas treated with catnip oil. Using a solid phase microextraction (SPME) method, the atmospheric concentration of catnip active ingredient compounds (nepetalactones) absorbed by SPME fiber in treated areas was detected at 4 times higher than those in control areas. Application of wax-based catnip pellets in cattle feedlots resulted in >99% repellency of stable flies in treated areas, compared with that in nontreated areas. However, the repellent efficacy of the formulation only lasted 3 h. This is the first study demonstrating the potential application of a plant-based repellent formulation that may be used as an alternative method against stable flies.

The mitochondrial genome of the common cattle grub, Hypoderma lineatum

The mitochondrial DNA of the cattle grub Hypoderma lineatum (de Villers) (Diptera: Oestridae) was completely sequenced. The entire molecule was 16,354 bp long and presented a heavy bias towards A + T, which accounted for 77.8% of the whole genome. Hypoderma lineatum genes were organized in the same order and orientation as in the mitochondrial genomes available for other species belonging to the Oestroidea superfamily and compared in this study [Chrysomya putoria (Wiedemann), Cochliomyia hominivorax (Coquerel), Lucilia sericata (Meigen) and Dermatobia hominis (L.)], except for the occurrence of a 102-bp non-coding region partially present in other species. The complete sequence of H. lineatum will represent a useful dataset to evaluate the evolutionary pattern of mtDNA within Oestroidea by using molecular information in diagnostic, taxonomic and evolutionary studies.

Of cattle, sand flies and men: a systematic review of risk factor analyses for South Asian visceral leishmaniasis and implications for elimination

BACKGROUND

Studies performed over the past decade have identified fairly consistent epidemiological patterns of risk factors for visceral leishmaniasis (VL) in the Indian subcontinent.

METHODS AND PRINCIPAL FINDINGS

To inform the current regional VL elimination effort and identify key gaps in knowledge, we performed a systematic review of the literature, with a special emphasis on data regarding the role of cattle because primary risk factor studies have yielded apparently contradictory results. Because humans form the sole infection reservoir, clustering of kala-azar cases is a prominent epidemiological feature, both at the household level and on a larger scale. Subclinical infection also tends to show clustering around kala-azar cases. Within villages, areas become saturated over a period of several years; kala-azar incidence then decreases while neighboring areas see increases. More recently, post kala-azar dermal leishmaniasis (PKDL) cases have followed kala-azar peaks. Mud walls, palpable dampness in houses, and peri-domestic vegetation may increase infection risk through enhanced density and prolonged survival of the sand fly vector. Bed net use, sleeping on a cot and indoor residual spraying are generally associated with decreased risk. Poor micronutrient status increases the risk of progression to kala-azar. The presence of cattle is associated with increased risk in some studies and decreased risk in others, reflecting the complexity of the effect of bovines on sand fly abundance, aggregation, feeding behavior and leishmanial infection rates. Poverty is an overarching theme, interacting with individual risk factors on multiple levels.

CONCLUSIONS

Carefully designed demonstration projects, taking into account the complex web of interconnected risk factors, are needed to provide direct proof of principle for elimination and to identify the most effective maintenance activities to prevent a rapid resurgence when interventions are scaled back. More effective, short-course treatment regimens for PKDL are urgently needed to enable the elimination initiative to succeed.

Echinococcus granulosus: biological comparison of cattle isolates from endemic regions of Argentina and Spain

In the present study we have compared cattle isolates of Echinococcus granulosus from Argentina and Spain. The aim was to compare and determine if there exist phenotypic and genetic differences within E. granulosus cattle isolates between an endemic area of Spain (where the disease is mainly restricted to a sheep-dog cycle) and an endemic area of Argentina (where cattle are the most abundant intermediate hosts). The Spanish samples were previously identified as G1 genotype. The Argentinean samples were also identified as G1, but some variants were found for the cytochrome c oxidase-1 (CO1) and NADH dehydrogenase-1 (ND1) mitochondrial genes. When comparing the cyst features and the morphology of the larval rostellar hooks in both regions, some differences were found. The morphometric analyses of the larval rostellar hooks showed the existence of two distinct clearly separated groups (one corresponding to the Argentinean samples and the other to the Spanish ones). In conclusion, there are some genetic and phenotypic differences within E. granulosus cattle isolates from Argentina and Spain. Probably these differences, more important from an epidemiological point of view, are related to different steps in the disease control in both countries. Further studies involving other epidemiological, morphometric and molecular data, including other types of livestock, would contribute to clarify and expand the present work.

Detection of Cryptosporidium spp. and Giardia duodenalis in surface water: a health risk for humans and animals

The objective of the present study was to determine the degree of contamination by Cryptosporidium spp. and Giardia duodenalis in a river basin in a livestock farming area in Galicia (NW, Spain). Water samples (50 l) were collected at 22 points in the main basin (including 5 recreational areas), and at the source and mouth of the 3 most important rivers and at the mouth of a smaller, secondary river. Faecal samples were collected from dairy cattle selected at random from 18 herds farmed in the area. A total of 139 neonatal calves, 480 heifers and 697 cows were sampled. The prevalence, intensity of infection and the risk associated with the spread of infection by both enteropathogens were determined. Water and faecal samples were collected in spring, summer, autumn and winter of 2007. The species and genotypes of these parasites present in the water samples were identified. In both water and faecal samples, more parasitic stages were collected in spring and summer than in autumn and winter. In spring, Cryptosporidium spp. oocysts were detected in 33 (9.4%) cows from 13 (72.2%) herds, and G. duodenalis cysts were detected in 56 (16.0%) cows from 15 farms (83.3%); the intensity of infection ranged from 5 to 7895 G. duodenalis cysts per gram of faeces. Infective stages of Cryptosporidium spp. and G. duodenalis were also detected in respectively 26 (89.6%) and 27 (93.1%) water samples, in spring. The mean concentrations of parasites ranged from 2 to 1200 Cryptosporidium spp. oocysts per litre and from 2 to 400 G. duodenalis cysts per litre. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The presence of both protozoans must be monitored in cattle, in sources of water used for recreational purposes and in artificial waterways used by farmers (water channels, animal drinking water and drainage systems).

[Chorioptic mange in dairy cattle: a new assessment for its control]

In the western region of Switzerland, the canton of Freiburg, the clinical and subclinical distribution of Chorioptes spp. was studied in 14 stables with tethered housing and 10 stables with loose housing, for a total of 667 dairy cows. Chorioptes infestations were diagnosed in 22 out of the 24 herds. In the 14 stables with tethered housing 33.8% of the dairy cows were clinically suspicious and 31% were found parasitologically positive. These values were higher than in the 10 stables with loose housing that had 26.5% clinically suspicious cases and 17.8% parasitologically positive cows. The collected clinical findings and parasitological diagnoses, as well as the analysed data of Chorioptes infestations allowed to determine a reference value for these herds which could be used by the practicing veterinarian as an aid in deciding whether to treat the whole herd or the single animal. In a cow population an amount of more than 12% of cows with clinically manifest Chorioptes spp. infestation reflects a problem concerning the whole herd and therefore the whole herd needs to be treated. If less than 12% of the cows are visibly infested and no subclinical Chorioptes cases are proven, then it only constitutes a problem of single animals and therefore can be dealt with individually. The treatment of the herds of two farms with tethered housing with Eprinomectin was very effective and showed a long lasting 100% antiparasitic effect which lasted more than 92 days after treatment.

[Two cases of Crimean-Congo haemorrhagic fever (CCHF) in two tourists in Senegal in 2004]

Two cases of Crimean-Congo haemorrhagic fever (CCHF) occurred in two French tourists during their visit in Senegal in November 2004. Febrile and hemorrhagic syndrome with ulorrhagia, petechiae, haematemesis, haematomas associated with biological signs of disseminated intramuscular coagulation were observed. For the first case who had a medical evacuation to France before diagnosis, Crimean-Congo virus infection was revealed by laboratory tests performed by the National Reference Center for Hemorrhagic Fevers (NRCHF, Institut Pasteur, Lyon) and secondly by the Centre de Référence OMS sur la Recherche des Arbovirus et des virus des Fièvres Hémorragiques (CRORA) in the Dakar Pasteur Institute (DPI). The second case diagnosed by the CRORA died after clinical deterioration with liver failure and severe haemorrhages. Healthcare workers and family members who had contact with tissue or blood from patients were followed up after the putative exposure either in France or in Senegal.

Detection and identification of rickettsial agents in ticks from domestic mammals in eastern Panama

Several outbreaks of Rocky Mountain spotted fever have occurred in recent years in Colombian communities close to the border with Panama. However, little is known about rickettsiae and rickettsial diseases in eastern Panamanian provinces, the Darien Province and the Kuna Yala, located north of the endemic area in Colombia. In 2007, 289 ticks were collected in several towns from dogs, horses, mules, cows, and pigs. DNA was extracted from 124 Dermacentor nitens, 64 Rhipicephalus sanguineus, 43 Amblyomma ovale, 35 A. cajennense, 10 Boophilus microplus, 4 A. oblongoguttatum, and 9 A. cajennense nymphs. SYBR-Green polymerase chain reaction assays targeting a fragment of the OmpA and 16S rRNA genes were used for detection of DNA of the spotted fever group rickettsiae (SFGR) and Anaplasmataceae (Anaplasma and Ehrlichia), respectively. In total, 37.4% ticks were positive for SFGR, including 20.3% R. sanguineus, 27.9% A. ovale, 25.8% D. nitens, 50% B. microplus, 50% A. oblongoguttatum, and 100% A. cajennense. The presence of Rickettsia amblyommii DNA was confirmed by sequencing in A. cajennense, A. oblongoguttatum, A. ovale, B. microplus, and R. sanguineus. DNA of R. rickettsii was only detected in one D. nitens collected from a horse in Santa Fe, Darien Province. Prevalence of Anaplasmataceae varied from 6.3% in R. sanguineus to 26.5% in A. cajennense. DNA of Ehrlichia chaffensis was found in three D. nitens and three A. cajennense from horses. This is the first study providing molecular characterization and prevalence information on SFGR in ticks from these areas and thus will be helpful for future evaluations of the risk of rickettsial diseases for individuals living in this region.

Quantification of Theileria parva in Rhipicephalus appendiculatus (Acari: Ixodidae) confirms differences in infection between selected tick strains

Theileria parva is the etiologic agent of East Coast fever, an economically important disease of cattle in sub-Saharan Africa. This protozoan parasite is biologically transmitted by Rhipicephalus appendiculatus (Neumann) (Acari: Ixodidae). An understanding of the vector-parasite interaction may aid the development of improved methods for controlling transmission. We developed quantitative polymerase chain reaction (qPCR) and nested PCR (nPCR) assays targeting the T. parva-specific p104 gene to study T. parva pathogenesis in two strains of R. appendiculatus that had previously been selected to be relatively more (Kiambu) or less (Muguga) susceptible to infection. Nymphs from both strains were fed simultaneously to repletion on acutely infected calves. Nymphs from the Kiambu strain showed significantly higher engorgement weights compared with Muguga strain nymphs. Immediately after engorgement qPCR confirmed that nymphal Kiambu ticks had significantly higher parasite loads at repletion than Muguga nymphs. By 12 d postengorgement, parasites were below quantifiable levels but could be detected by nPCR in 83-87% (Muguga and Kiambu, respectively) of nymphs. After the molt, adult feeding on naïve cattle stimulated parasite replication in the salivary glands. PCR detected significantly more infected ticks than microscopy, and there was a significant difference between the two tick strains both in the proportion of ticks that develop salivary gland infections, and in the number of parasites within infected salivary glands. These data confirm that although both tick strains were competent vectors, Kiambu is both a significantly more susceptible and a more efficient host for T. parva than Muguga. The mechanisms that contribute to the levels of susceptibility and efficiency are unknown; however, this study lays the groundwork for a comparison of the transcriptome of these tick strains, the next step toward discovering the genes involved in the tick-parasite interaction.

A report on the prevalence of gastrointestinal parasites in yaks (Bos poephagus) in the cold desert area of North Sikkim, India

Faecal samples were collected from 348 yaks(Bos poephagus) in and around Gurudogmer Plateau, a cold desert area in North Sikkim, India. The prevalence of gastrointestinal parasitic infection was recorded at 10.05% in both the organized and traditionally managed farms of yak. The pattern of infection was either single (2.58%) or mixed (7.47%) with a faecal egg count range of 100-200 eggs per gram of faeces in positive animals. Among the helminths, Haemonchus spp. infection was predominant (6.89%) followed by Nematodirus spp. (1.72%), Cooperia spp. (1.43%) and Dicrocoelium spp. (0.29%).

Onchocerciasis Due to O. armillata in Cattle in Orissa

The incidence of aortic onchocerciasis was investigated by examining 167 aortas of adult cattle; of these 165 were positive for parasites and nodules.

Five young calves, aged between 3 and 6 months did not reveal any aortic infection, indicating that the infection is seen in adult animals mostly.

The affected aortas are invariably sclerosed, the degree of sclerosis being dependent on the degree of infestation; and the aortic nodules containing worms and microfilariae are seen on both sides but those on the outer wall mostly undergo degeneration and subsequent calcification while the nodules on the inner aspect permit the passage of microfilariae into the circulation.

Some observations on the free-living stages of Ostertagia ostertagi, a stomach worm of cattle

Outdoor observations were made on the rate of development of the free-living stages of O. ostertagi at different times of the year, and on the migratory activities and longevity of the larvae in faeces, on herbage and in soil.

The effect of temperature on the rate of development of eggs and larvae in faeces, and the effect of temperature and humidity on the longevity of eggs and larvae when separated from faeces, were studied in the laboratory.

The results of these observations are discussed in relation to translation (that is, the process whereby eggs in faeces become infective larvae on herbage available to the grazing animal) and to the transmission of infection in the field.

I wish to thank Mr J. F. Michel for providing the infected faeces, and Mr D. A. Griffiths for technical assistance.

Cattle can develop immunity to paralysis caused by Dermacentor andersoni

Cattle exposed to a paralyzing strain of Dermacentor andersoni (Stiles) were all paralyzed during an initial exposure, but the incidence of paralysis decreased to 17 and 0% after two subsequent exposures to virulent flat ticks. Cattle with a single exposure to paralyzing ticks became paralyzed when challenged with ticks that had been prefed on cattle. Western blots indicated that cattle developed antibody responses to 13 antigens in paralyzing tick saliva. The likelihood of paralysis was inversely related to the number of saliva proteins that cattle developed antibody responses to. Cattle challenged with prefed ticks developed antibody response to fewer saliva antigens than cattle challenged with flat ticks. Variation in tick dose did not influence the expression of paralysis. Daily survival of ticks was similar on all groups of cattle, and tick weight was not reduced on previously challenged cattle, indicating immunity developed to the paralysis toxin rather than tick feeding. Four saliva antigens (molecular weights ranging from 36.9 to 42.2 kDa) were associated with the development of immunity to paralysis.

[Epidemiological survey on echinococcosis in Darlag County of Qinghai Province]

OBJECTIVE

To make an epidemiological investigation on echinococcosis in Darlag County, Guoluo Tibetan Autonomous Prefecture of Qinghai Province.

METHODS

Local participants were screened for echinococcosis using B ultrasound from August to September in 2007. IHA was carried out to detect antibody in human sera. Indirect ELISA using recombinant-AgB and Em18 antigen was conducted to further diagnose the human alveolar echinococcosis (AE) and cystic echinococcosis (CE) . The prevalence of echinococcosis in wild rodents, yaks, sheep and dogs was examined either by dissection or through slaughterhouses. Adult worms and hydatid cysts were detected by PCR-RFLP to discriminate 3 Echinococcus species and genotype of Eg. Dog feces were tested by double antibody sandwich ELISA method to confirm the coproantigen positive rate.

RESULTS

1723 people were examined by ultrasound and 236 were clinically diagnosed as hydatid diseases with an overall morbidity of 13.7%, of which 5.5% were CE and 8.2% were AE. Prevalence in males and females was 11.6% and 15.6% respectively with a statistically significant difference (chi2=7.0, P< 0.05) . Prevalence in herdsmen and monks/nuns was as high as 23.0% and 13.2%, respectively. Adult worms were found in 5 out of 9 stray dogs by necropsy. 27 of 239 pikas (Ochotona curzoniae) were infected by E. shiquicus (11.3%). CE prevalence in sheep and yaks was 26.4% and 5/16 respectively. The Eg genotype was G1 (sheep strain).

CONCLUSION

Three species of Echinococcus, e.g. E. granulosus, E. multilocularis and E. shiquicus are all prevalent in Darlag County. The prevalence of both AE and CE in human population is high in the area. Domestic dogs are the primary definitive host for both E. granulosus and E. multilocularis.

[Investigation on echinococcosis in animals in Gannan Tibetan Autonomous Prefecture]

OBJECTIVE

To make an investigation on echinococcosis among animals in Gannan Tibetan Autonomous Prefecture.

METHODS

21 villages from Maqu and Luqu counties were selected for the survey in August of 2004-September of 2007. Rodents were trapped in the field. Sheep and yak livers, hearts and lungs were collected from the local slaughterhouses for pathological examination. Domestic dogs (shepherd dogs) were de-wormed by 15% arecoline to receive adult worms and stray dogs were shot for dissection.

RESULTS

The prevalence of alveolar echinococcosis (AE) in Ochotona dahurica was 1.2% (1/87), and 2.3% (3/132) in Myospalax fontaniere, but no infection was found in Marmota himalayana, Ochotona tibetana and Mus musculus. 113 out of 1021 (11.1%) sheep were found infected with cystic echinococcosis (CE), and 3 (0.3%) with AE. 126 out of 634 (19.9%) yaks were infected with CE, and 2 yaks (0.3%) with AE. 17 out of 74 (23.0%) dogs were infected with Echinococcus granulosus (Eg), and 4 (5.4%) with Echinococcus multilocularis (Em).

CONCLUSION

The results showed that there is a widespread endemic of Echinococcus granulosus in dogs and wild animals in Gannan Tibetan Autonomous Prefecture, with less Echinococcus multilocularis infection.

Allopatric speciation in ticks: genetic and reproductive divergence between geographic strains of Rhipicephalus (Boophilus) microplus

BACKGROUND

The cattle tick, Rhipicephalus (Boophilus) microplus, economically impact cattle industry in tropical and subtropical regions of the world. The morphological and genetic differences among R. microplus strains have been documented in the literature, suggesting that biogeographical and ecological separation may have resulted in boophilid ticks from America/Africa and those from Australia being different species. To test the hypothesis of the presence of different boophilid species, herein we performed a series of experiments to characterize the reproductive performance of crosses between R. microplus from Australia, Africa and America and the genetic diversity of strains from Australia, Asia, Africa and America.

RESULTS

The results showed that the crosses between Australian and Argentinean or Mozambican strains of boophilid ticks are infertile while crosses between Argentinean and Mozambican strains are fertile. These results showed that tick strains from Africa (Mozambique) and America (Argentina) are the same species, while ticks from Australia may actually represent a separate species. The genetic analysis of mitochondrial 12S and 16S rDNA and microsatellite loci were not conclusive when taken separately, but provided evidence that Australian tick strains were genetically different from Asian, African and American strains.

CONCLUSION

The results reported herein support the hypothesis that at least two different species share the name R. microplus. These species could be redefined as R. microplus (Canestrini, 1887) (for American and African strains) and probably the old R. australis Fuller, 1899 (for Australian strains), which needs to be redescribed. However, experiments with a larger number of tick strains from different geographic locations are needed to corroborate these results.