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PubMed1994

Relationship between the persistence of African swine fever and the distribution of Ornithodoros erraticus in the province of Salamanca, Spain.

For some time it has been known that the tick Ornithodoros erraticus might be one of the causes of the persistence of African swine fever in the Iberian Peninsula since its introduction in 1960. In the province of Salamanca serological methods have been used to study the relationship between the presence of the tick in different townships and the outbreaks of African swine fever in these townships between 1987 and 1992. The results showed that there was a statistically significant association between the presence of the parasite and the persistence of African swine fever. In townships without O erraticus traditional methods of control are in most cases enough to avoid new outbreaks of the disease, but in areas with O erraticus the traditional methods should be reinforced by other methods for preventing contact between pigs and the parasite.

African Swine Fever↗
PubMed1976

The effect of erythromycin on the growth of Rickettsia prowazekii in the body louse (Pediculus humanus corporis L) and the tick (Ornithodoros moubata Murray).

Body lice (Pediculus humanus corporis L) and ticks (Ornithodoros moubata) that had been infected with Rickettsia prowazekii received varying doses of erythromycin. The anti-rickettsial activity of this drug was evaluated with regard to the determination of the numbers of surviving microorganism (LID100) and the in vivo concentration of erythromycin in both arthropod hosts. Erythromycin was found to exert a rickettsiostatic effect in lice, whereas in ticks the drug at concentrations of 0.3--0.04 mug/mg body weight completely eliminated R. prowazekii.

Animals↗
PubMed2006

Two secreted cystatins of the soft tick Ornithodoros moubata: differential expression pattern and inhibitory specificity.

Two genes coding for cysteine peptidase inhibitors of the cystatin family (Om-cystatin 1 and 2) were isolated from a gut-specific cDNA library of the soft tick Ornithodoros moubata. Both cystatins were clearly down-regulated after a blood meal. Om-cystatin 1 is mainly expressed in the tick gut, while Om-cystatin 2 mRNA was also found in other tick tissues. Authentic Om-cystatin 2 was significantly more abundant than Om-cystatin 1 in the gut contents of fasting ticks and was associated with hemosome-derived residual bodies accumulated in the gut lumen. Om-cystatin 2 was also expressed by type 2 secretory cells in the salivary glands of unfed ticks. The inhibitory specificity of recombinant Om-cystatins 1 and 2 was tested with mammalian cysteine peptidases, as well as endogenous cysteine peptidases present in the tick gut. Both cystatins efficiently inhibited papain-like peptidases, including cathepsin B and H, but differed significantly in their affinity towards cathepsin C and failed to block asparaginyl endopeptidase. Our results suggest that the secreted cystatin isoinhibitors are involved in the regulation of multiple proteolytic targets in the tick digestive system and tick-host interaction.

Amino Acid Sequence↗
PubMed2004

Detection of human blood in the bat tick Carios (Ornithodoros) kelleyi (Acari: Argasidae) in Iowa.

The argasid tick Carios (Ornithodoros) kelleyi Cooley & Kohls is a common ectoparasite of bats and has been found in massive numbers in homes with associated bat colonies in eastern Iowa. This tick feeds nearly exclusively on bats in nature. Several inhabitants of infested homes complained of "bug bites" at night while asleep that may have resulted in erythematous, edematous, urticaric skin lesions and constitutional signs and symptoms. We provide laboratory evidence that a single, engorged C. kelleyi nymph contained host blood from a human female. The clinical implications of our findings are intriguing but unclear.

Animals↗
PubMed1978

Johnston Atoll virus (Quaranfil group) from Ornithodoros capensis (Ixodoidea: Argasidae) infesting a gannet colony in New Zealand.

Ten strains of Johnston Atoll (JA) virus were isolated from Ornithodoros capensis collected in a Gannet (Sula bassana serrator) colony in New Zealand. Its sensitivity to ether and sodium deoxycholate were confirmed and it was shown to have an RNA genome. It multiplied in day-old chicks but, unlike the prototype virus, it was not pathogenic for them. Transmission experiments and the high incidence of birds with neutralizing antibody indicate that the virus is maintained in the colony by a cycle involving ticks and Gannets. This is the first recorded tickborne arbovirus in New Zealand and extends the known range of JA virus from the tropics into the temperate zone.

Animals↗
PubMed1985

Experimental studies on the replication and dissemination of Qalyub virus (Bunyaviridae: Nairovirus) in the putative tick vector, Ornithodoros (Pavlovskyella) erraticus.

A study was undertaken to determine if the argasid tick, Ornithodoros (Pavlovskyella) erraticus, can serve as a biological vector of Qalyub (QYB) virus. The suckling mice used as viremic vertebrate hosts were acceptable hosts for all feeding stages of this tick and developed relatively high titered viremias (4.4-6.5 log10PFU/ml) 24-120 hr post intracerebral inoculation. Larval, nymphal, and adult ticks became orally infected with QYB virus after ingesting 4.4-6.4 log10PFU/ml. The overall infection rate for all experiments was 67/205 and virus was recovered up to day 179 postfeeding. Incubation of known quantities of QYB virus with uninfected triturated tick tissues did not result in any appreciable virus inactivation. QYB viral antigen was detected by immunofluorescence primarily in the tick midgut posterior diverticula cells. First and second instar nymphs orally infected as larvae did not individually transmit QYB virus to suckling mice; however they successfully transmitted the virus when feeding in groups of 11-20 per mouse. Three out of fourteen of the orally-infected male and female ticks individually transmitted QYB virus orally to suckling mice. Organ titrations of ticks orally exposed to QYB virus demonstrated virus primarily in midgut tissues; dissemination to other organ systems was discovered in only 1 tick after 142 days extrinsic incubation. Vertical transmission of virus from infected female ticks to progeny was not demonstrated. Four of the 39 ticks in our colony were infected with a spirochete; presumably, Borrelia crocidurae. O. (P.) erraticus apparently satisfies the conditions that would implicate this species as a biological vector of QYB virus and is the only known arthropod from which this virus has been isolated in nature.

Animals↗
PubMed1986

Identification of African swine fever viral antigens in the hemolymph of soft ticks (Argasidae: Ornithodoros) by the immunodot blot test.

The immunodot blot test was used to identify African swine fever virus (ASFV) antigens in the hemolymph from soft ticks (Ornithodoros coriaceus) fed on ASFV-infected pigs. The immunodot blot test was sensitive and specific for ASFV antigens and has potential field application. Hemolymph from field-collected ticks can be screened for ASFV and a variety of other tick-borne pathogens using this test.

African Swine Fever Virus↗
PubMedDate not supplied

[Comparative study of the bactericidal action of the body of Ornithodoros papillipes ticks].

Experiments in vivo have shown that the ticks of Ornithodoros papillipes inhibit both Gram-positive and Gram-negative bacteria. On Gram-positive microorganisms most sensitive to bactericidal effect of ticks have turned to be micrococci, staphylococci, streptococci and bacteria of diphtheria, of Gram-negative ones--Bacillus coli. Of Gram-positive microorganisms less sensitive were Listeria, of Gram-negative ones--salmonellae, agents of tularemia and pseudotuberculosis. At the infection with bacteria the organism of the tick produces a bactericidal substance which causes the dying off of the microbal population. The ability of the bactericidal substance to lyse the inhibited cells of Micrococcus lysodeiktickus as well as the coincidence of data on sensibility to the tick bactericidal substance obtained experimentally in vitro and in vivo have shown that lysozyme is an active antibacterial substance in the tick's organism.

Animals↗
PubMed2000

Seasonal abundance of Ornithodoros (O.) savignyi and prevalence of infection with Borrelia spirochetes in Egypt.

The seasonal dynamics of Ornithodoros (O.) savignyi and infection with Borrelia sp. in the tick, domestic animals and man were investigated in the village of Dahshore, Giza governorate from August 1996 through July 1997. The tick population densities of adults and immatures were high during the period from June to October with maximum levels in August and September respectively. Adults predominated (58.6%-80.0%) in October to May with the highest abundance in January while immatures prevailed (51.3%-65.8%) during the rest of the year reaching a peak in September. Of 1202 tick examined, the spirochetes were detected in 427 (35.5%). The annual infection rate in adults and immatures varied from 34.4%-36.9% with no significant difference among larvae, nymphs, males and females. Of 1396 sera from man and 553 sera from host animals tested, 309 (22.1%) and 157 (28.4%), respectively, were reactive for antibody to Borrelia sp. antigen with the highest infection rate in camel (47.8%), followed by sheep (23.8%), goat (18.0%) and cow (16.0%), then the least in buffalo (10.9%). Changes in prevalence of Borrelia infection in the tick population correlated positively with changes in antibody prevalence in man and camel and with changes in the tick population density. The four events were lowest in winter and early spring and increased afterward to reach maxima during summer or the early fall (July-September).

Adult↗
PubMed2000

Immune responses of the argasid tick Ornithodoros moubata moubata induced by infection with the filarial worm Acanthocheilonema viteae.

Investigations were undertaken to determine whether the tick Ornithodoros moubata moubata mounted a detectable immune response to primary and secondary infections with Acanthocheilonema viteae. Uninfected control tick survival rate was 70%, but only 45% in the primary infection group. Post-secondary infection survival rate (82%) was comparable to controls, indicating that these selected ticks had some protective advantage. Mean A. viteae infective larvae recovery from ticks with secondary infections was 31.4% lower than expected, suggesting the development of immunity. SDS-PAGE of haemolymph for proteins induced post-primary infection yielded a stronger signal at 45 kDa than controls, which was further elevated post-secondary infection. Proteins at 48, 22 and 16 to 18 kDa were detected in haemolymph from infected ticks but not seen from controls. The direct effect of haemolymph on microfilarial viability was examined using a novel in vitro assay; in these preliminary trials no differences were observed in parasite viability when exposed to haemolymph from infected or uninfected groups of ticks.

Animals↗
PubMed2001

Mortality caused by experimental infection with the yeast Candida haemulonii in the adults of Ornithodoros moubata (Acarina: Argasidae).

A relatively high rate of mortality among engorged females of Ornithodoros moubata (Murray, 1877) was observed in our laboratory colony. The general aim of the study was to identify the causative agent responsible for this mortality. The diagnostic tests were performed by Yeast Identification Service (CBS-Delft, Netherlands) and the pathogen was identified as the yeast Candida haemulonii (van Uden et Kolipinski, 1962) Meyer et Yarrovi, 1978. The artificial infection study was performed by intrahaemocoelic inoculation of yeast suspension, resulting in a mortality of 37%. The maximum mortality of ticks infected per os by contaminated blood meal was 13%. Re-isolated yeast cells from haemolymph of dead and paralysed ticks were apparently identical with primary yeast cells, without loosing reproductive abilities. An occasional formation of elongated chains of yeast cells (pseudomycelium) was recorded. The majority of ticks infected in both experiments mentioned above survived and displayed no evident symptoms of the infection. The presence of yeast cells in the haemolymph of surviving ticks was not detected. The in vitro phagocytosis assay performed with FITC-labelled yeast cells showed that about 4% of tick haemocytes were phagocytically active against the pathogenic yeast cells. Thus phagocytosis seems to be a potent defence reaction against spreading and multiplying of the yeast C. haemulonii within the tick haemocoel.

Animals↗
PubMed1975

[Observations on the behaviour of coxiella burneti in the argasid tick ornithodoros moubata (author's transl)].

Based on a long-term study of many years, a report is given on the behaviour of Coxiella burneti in the argasid tick, Ornithodoros moubata. Recent observations were made on ticks infected on mice and subsequently maintained separately. Particular emphasis was placed upon the localization of the ricksettsiae in certain organs of the ticks, its excretion -also with regard to routes of transmission - and transovarial passage. C. burneti invade primarily the gut epithelial cells of the tick and these cells remain infested with the causative agent throughout the entire life of the vector. After a certain infection period, other organs of the tick may become also infected. Thus, infection of the coxal organ, of salivary glands, rectal ampullae and ovaries has been confirmed through the presence of the rickettsiae in the coxal fluid, saliva and excreta or through transovarial passage of the agent with the saliva during feeding transmission to a new host takes place. Infection of the various organs of the tick and excretion or passage of the agent is not necessarily the rule, but may be even considered as an exception. This is especially the case for transovarial passage. On the other side, the multiplication of rickettsiae in the tick can be so intensive that the haemolymph and all internal organs become flooded with the organisms. These observations have been made in moribund and dead ticks. One of the most remarkable results was that the behaviour of C. burneti in its tick host varied considerably not only within the same series of experiments but more frequently in one and the same individual tick as well. Thus, e.g. excretion of the agent - with the saliva or coxal fluid - could be interrupted and resumed again later on. Evidently, these variations indicate a shift in the host-parasite interrelationship in which the multiplication of the rickettsiae is greatly enhanced by a decrease in the host's immune response, whereas an increase in its defence reaction will cause suppression of multiplication. It is not known, however, if the relevant impulse is primarily given by the tick or the rickettsial organism. The behaviour of C. burneti in O. moubata which does not follow a definite pattern coincides well with the high adaptability and variability characterizing this microorganism in other aspects as well.

Animals↗
PubMed1992

[The use of cryopreserved swine blood for in vitro feeding of the soft tick Ornithodoros moubata].

Porcine stored blood has been used in the in vitro feeding of the soft tick Ornithodoros moubata through a Parafilm membrane. The efficiency of the feeding decreased after storage of 5 weeks by -20 degrees C. Through addition of 10(-3) M ATP/l the feeding results with frozen blood for duration of storage up to 200 days well agreed with the results of feeding tests with fresh porcine blood: The nymphs (N)1-3 fed the 4-5fold, the N4-6 the 2.7fold and the adults (A) the 1.9fold of their body weight. The feeding rate was 98.6% (N1-3); 92.7% (N4-5) and 81.9% (A). The mortality rate was under 10%. Females laid 130 eggs after blood meal.

Animals↗
PubMed1992

Role of synganglion in oogenesis of the tick Ornithodoros parkeri (Acari: Argasidae).

The role of the synganglion in oocyte development in Ornithodoros parkeri was investigated by ligation and transplantation experiments. Ligation between legs 2 and 3 to isolate the synganglion from the ovary and ligation between legs 1 and 2 to keep both the synganglion and the ovary in the posterior ends were performed on mated females on different days after feeding. Results show that vitellogenesis was inhibited significantly if the synganglion was separated from the ovary within the first few days after feeding. However, transplantation of synganglia from 3 kinds of donors (unfed virgin, fed virgin, and fed mated females) into the synganglionless posterior portions induced vitellogenesis and oocyte development to final maturation. The supra- and subesophageal parts of the synganglion showed a similar gonadotropic activity after each was transplanted separately into the ligated synganglionless posterior portions. These results indicate that the synganglion produces an egg development stimulation factor (EDSF) that possibly is present in a storage form in unfed and/or fed virgin females in which vitellogenesis has not progressed and is released in females after feeding and mating. However, the characterization of EDSF and precise sites of production and storage await further investigation.

Animals↗
PubMed1990

Relationships between the defensive systems of Iberian-breed swine and the European vector of African swine fever, Ornithodoros erraticus.

To discover whether the immune system of Iberian-breed pigs exerts any adverse action on Ornithodoros erraticus, 3 pairs of pigs were subjected to a weekly infestation over 12 wk with 1,000 larvae, 500 nymphs-1, or 200 adults. Each pair was bitten by only 1 developmental stage. Batches of parasites identical to the foregoing ones were fed weekly on control swine. In none of the 10 parameters studied for each of the batches fed weekly was any significant difference found that could be attributed to the state of sensitization of the animals in which, in a previous study, the presence of high titers of anti-O. erraticus antibodies was found. It was observed that the possible pruritus due to immediate hypersensitivity reactions, which in the test animals appeared after the third week, had no protective value in the natural milieu. In view of the inability of the swine to exert any control over the soft ticks, it is concluded that the size of their populations in the pig pens and their composition according to the developmental stage are factors that depend exclusively on the opportunities that swine breeders offer such populations to feed on the animals.

African Swine Fever↗
PubMed1990

Distribution and biology of Ornithodoros erraticus in parts of Spain affected by African swine fever.

Ornithodoros erraticus was found in 30.7 per cent, 35.0 per cent and 71.0 per cent of the pig-pens sampled in the provinces of Salamanca, Badajoz and Huelva in which African swine fever is a problem in the rearing of Iberian pigs. Between 38 and 65 per cent of the pig-pens in these areas are now abandoned and their populations of O erraticus are extinct or becoming so because they can no longer feed on pigs, which in Spain are their main hosts. The abandonment of pig-pens has resulted in the elimination of most soft ticks infected with the virus of African swine fever, and means that the distribution of ticks is now irregular and focal. Another factor affecting their distribution is the kind of soil on which the pig-pens are located. In abandoned pig-pens, the adults and large nymphs survive for about five years or longer when animals occasionally enter them. Hungry tick populations may transmit African swine fever when feeding in winter, whereas the populations that have continuous access to pigs do not feed until the pig-pens reach a temperature of 13 to 15 degrees C. In the latter populations, each stage exhibits a single annual peak of activity, which implies that the development from larva to adult takes two to three years. Pigs may die as a result of the bites, but on no occasion were 100 per cent of the fasting ticks seen to feed, even though they had the opportunity of doing so. This may hinder the eradication of this soft tick from infested pig-pens.

African Swine Fever↗