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PubMed2005

Biochemical diagnosis of organophosphate-insensitivity with neural acetylcholinesterase extracted by sonication from the adult tick synganglion.

A sonication method for the homogeneous extraction of acetylcholinesterase (AChE) from the synganglia of adult ticks is described. The method provides for the extraction of sufficient AChE for multiple assays of enzyme activity in the presence of specific organophosphate (OP) inhibitors for the rapid diagnosis of OP-insensitivity and assignment of homozygous susceptible (SS), heterozygous resistant (RS), and homozygous resistant (RR) genotypes to individual ticks. A single synganglion from adult ticks of either gender and various stages of feeding can successfully be used for AChE extraction. The study presents the results of diagnostic screening of four Boophilus microplus strains for OP-insensitivity. The extraction method and these findings should find utility in support of researchers involved in the mitigation of acaricide resistance in tick populations worldwide, and in particular, the Cattle Fever Tick Surveillance and Quarantine Program maintained by USDA-APHIS/Veterinary Services along the south Texas border that prevents reentry of Boophilus spp. into the United States from endemic populations in Mexico.

Acetylcholinesterase↗
PubMedDate not supplied

Spraying tick-infested houses with lambda-cyhalothrin reduces the incidence of tick-borne relapsing fever in children under five years old.

Tick-borne relapsing fever (TBRF) is a major cause of morbidity and mortality of children in central Tanzania. This study assessed the effect of house interior residual spraying with lambda-cyhalothrin on domestic tick infestation and the incidence of TBRF in children under 5 years old. Two neighbouring villages were studied: one was sprayed with insecticide, the other left untreated. Samples of earth from the floors of 50 houses before and after spraying, and 50 houses in the control village, were sieved and ticks counted. The incidence of TBRF was estimated by microscopy of thick blood films taken from all children under 5 years old presenting with fever to the village dispensary or health workers. After 2 cycles of spraying, no tick was found in the treated houses; in the controls, tick numbers remained high. In the treated village there were 29 cases of TBRF among the 960 children under 5 years old in the 4 months before spraying, and one in the 4 months after spraying. In the control village there were 10 and 4 cases in the same periods among the 510 children. There was a significant reduction of 0.09 in the odds ratio of infection after spraying (95% confidence interval 0.01-0.87).

Child, Preschool↗
PubMedDate not supplied

[Current status of the foci and morbidity of tick-borne relapsing fever in Uzbekistan].

The contemporary state of settlement nidi of tick-borne relapsing fever is discussed on the material collected in the Namanganskaya and Andizhanskaya regions of Uzbek SSR. Despite the control measures and rise of the sanitary culture of population the conditions are still preserved for the maintenance of nidi. As in ancient estates, classical nidi of tick-borne relapsing fever, so in modern ones there are preserved conditions for existence of flourishing populations of vectors, i.e. favourable habitats and the availability of hosts. The analysis of factors is given affecting the contemporary level of sick-rate with tick-borne relapsing fever. Within the limits of the distribution area of the vector a higher sick-rate should be expected than it is registered.

Animals↗
PubMed1978

Tick-borne relapsing fever in the Eastern United States.

Tick-borne relapsing fever is endemic in the western part of the United States, but it has not been reported east of the Mississippi River. Sporadic cases have been reported in the eastern part of the United States, but travel to the West during the incubation period appeared to provide the source of infection. In the fall of 1975, a case of relapsing fever was diagnosed in Cincinnati in a child who had not traveled outside of Ohio, indicating the presence of Borrelia in this area. Serial serological studies indicated that B turicatae was the species involved. The occurrence of this case suggests that relapsing fever may exist in the eastern part of the United States, but its presence may not be appreciated because of the rarity of the disease and the difficulty in confirming the diagnosis.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Changes in the village foci of tick-borne relapsing fever in Uzbekistan over a 10-year period].

The paper presents the results of repeated investigations in the tick relapsing fever nidus (TRF) conducted after a ten-year interval in Gava settlement situated in the foothill area of the Namangan Province of Uzbekistan. A considerable deterioration in the habitat conditions of the vector, Ornithodoros papillipes Bir., due to the intensified anthropogenic effect, and decrease in its number have been noted. The distribution range of the tick (percent of infested farmsteads) in this case did not reduce. The infection rate of the vector's population with the tick relapsing fever agent decreased that points indirectly to a higher mortality of infected ticks under unfavourable conditions. Wavy course of morbidity with TRF during the period between investigations shows that changes that took place in the nidus were not uniform in their character and may have resulted to some extent from natural cycles. A similar character of anthropogenic effect on the populations of ticks in the settlement natural nidi suggests that the above changes are common to the nidi of this infection.

Animals↗
PubMed2001

Pathogenesis of African swine fever virus in Ornithodoros ticks.

African swine fever virus (ASFV) is the only known DNA arbovirus and the sole member of the family Asfarviridae. It causes a lethal, hemorrhagic disease in domestic pigs. ASFV is enzootic in sub-Saharan Africa and is maintained in a sylvatic cycle by infecting both wild members of the Suidae (e.g. warthogs) and the argasid tick Ornithodoros porcinus porcinus. The pathogenesis of ASFV in O. porcinus porcinus ticks is characterized by a low infectious dose, lifelong infection, efficient transmission to both pigs and ticks, and low mortality until after the first oviposition. ASFV pathogenesis in warthogs is characterized by an inapparent infection with transient, low viremic titers. Thus O. porcinus porcinus ticks probably constitute the most important natural vector of ASFV, although both the mammalian and tick hosts are probably required for the maintenance of ASFV in the sylvatic cycle. The mechanism of ASFV transmission from the sylvatic cycle to domestic pigs is probably through infected ticks feeding on pigs. In addition to O. porcinus porcinus, a number of North American, Central American and Caribbean species of Ornithodoros have been shown to be potential vectors of ASFV.

African Swine Fever↗
PubMed1988

Isolation of African swine fever virus from ticks of the Ornithodoros moubata complex (Ixodoidea: Argasidae) collected within the African swine fever enzootic area of Malawi.

Ticks of the Ornithodoros moubata complex were collected from domestic pig sties and dwelling houses, and from a warthog habitat, and tested for the presence of African swine fever (ASF) virus. Collections were made in 9 of the 24 districts of Malawi, these being primarily the districts in which O. moubata is most numerous. ASF virus was isolated from ticks collected in both domestic pig sties and houses in certain villages in Mchinji district where ASF outbreaks had recently occurred. Mchinji district is in the centre of a large ASF enzootic area which stretches into other districts of Malawi and also into Zambia and Mozambique. The high titre of virus in some of the ticks demonstrates that O. moubata can act as a virus reservoir and potential vector of disease in the field situation in Malawi.

African Swine Fever↗
PubMed1991

[An immunoenzyme test system for detecting rickettsiae of the tick-borne spotted fever group].

An enzyme immunoassay (EIA) test system has been developed for the detection of tick spotty fever (TSF) group Rickettsia. A long scheme of immunization in an isogenic system on rabbits has been used with an adjuvant without bacterial components, and based on aluminum hydroxide. This EIA test system detects whole soluble R. akari, R. sibirica, and R. conorii antigens and is at least 10-20 times more sensitive than the indirect hemagglutination test. Treatment in a temperature gradient permits the detection of the corpuscular antigen. A considerable vector infection rate has been revealed in individual examinations of ticks in foci of tick rickettsiasis, whereas such studies carried out in nonendemic areas brought negative results.

Animals↗
PubMed1989

Hemorrhagic fever with renal syndrome.

Hantaviruses, the causative agents of HFRS, have become more widely recognized. Epidemiologic evidence indicates that these pathogens are distributed worldwide. People who come into close contact with infected rodents in urban, rural and laboratory environments are at particular risk. Transmission to man occurs mainly via the respiratory tract. The epidemiology of the hantaviruses is intimately linked to the ecology of their principal vertebrate hosts. Four distinct viruses are now recognized within the hantavirus genus and that number is likely to increase to six very soon; however, further investigations are necessary. Much more work is still needed before we fully understand the wide spectrum of clinical signs and symptoms of HFRS as well as the pathogenicity of the different viruses in the hantavirus genus of the Bunyaviridae family. HFRS is difficult to diagnose on clinical grounds alone and serological evidence is often needed. A fourfold rise in IgG antibody titer in a 1-week interval, and the presence of the IgM type of antibodies against hantaviruses are good evidence for an acute hantavirus infection. Physicians should be alert for HFRS each time they deal with patients with acute febrile flu-like illness, renal failure of unknown origin and sometimes hepatic dysfunction. Especially the mild form of HFRS is difficult to diagnose. Acute onset, headache, fever, increased serum creatinine, proteinuria and polyuria are signs and symptoms compatible with a mild form of HFRS. Differential diagnosis should be considered for the following diseases in the endemic areas of HFRS: acute renal failure, hemorrhagic scarlet fever, acute abdomen, leptospirosis, scrub typhus, murine typhus, spotted fevers, non-A, non-B hepatitis, Colorado tick fever, septicemia, dengue, heartstroke and DIC. Treatment of HFRS is mainly supportive. Recently, however, treatment of HFRS patients with ribavirin in China and Korea, within 7 days after onset of fever, resulted in a reduced mortality as well as shortened course of illness.

Animals↗
PubMed1995

An overview of tick-borne relapsing fever with emphasis on outbreaks in Texas.

Tick-borne relapsing fever (TBRF), a disease of humans and other animals, has been recognized in North America since early in this century. Caused by Borrelia spirochetes, TBRF is transmitted by softshelled Ornithodoros ticks, which may also act as reservoirs for the etiologic agents. Initial symptoms include sudden onset of fever, chills, headache, arthralgias, and myalgias. Persons with TBRF may suffer several febrile episodes or relapses unless they are diagnosed and treated promptly because TBRF spirochetes are able to alter their outer surface proteins and, thus, escape the infected host's immune response. Laboratory diagnosis is made by detecting spirochetes in peripheral blood specimens or by inoculating laboratory mice with blood collected during febrile episodes. In the 1930s and '40s, TBRF was reported commonly in Texas. More recently, fewer cases have been reported, although 13 cases were confirmed between 1990 and the first half of 1994.

Animals↗
PubMedDate not supplied

[Tick-borne relapsing fever morbidity in the western Pamirs].

Morbidity with tick-borne recurrent fever in the western Pamirs is compared with that of the 1930s. It reduced considerably though the disease is widespread in the Pandj valley. The majority of patients are earlier resistant local inhabitants. This may be accounted for by vector number decrease to the level causing loss of immunity in the large part of the population. Unlike even distribution of recurrent fever in the western Pamirs in the 1930s, nowadays most cases are detected in the lower parts of the Pandj valley and there are no infection foci in the upper parts, which might be connected with gradual increase in the portion of immune population up the Pandj river and with diagnosis inadequacy. The incidence of recurrent fever in the Pamirs is considerably higher than in other parts of Tajikistan.

Age Factors↗
PubMed2003

Tick-borne relapsing fever caused by Borrelia hermsii, Montana.

Five persons contracted tick-borne relapsing fever after staying in a cabin in western Montana. Borrelia hermsii was isolated from the blood of two patients, and Ornithodoros hermsi ticks were collected from the cabin, the first demonstration of this bacterium and tick in Montana. Relapsing fever should be considered when patients who reside or have vacationed in western Montana exhibit a recurring febrile illness.

Adolescent↗
PubMed2002

The epidemiology of tick-borne relapsing fever in the United States.

Each year, many residents of and visitors to endemic regions of the western United States are exposed to the vector of tick-borne relapsing fever (TBRF), an underrecognized and underreported disease. Through review of report forms and literature review, we identified 450 cases of TBRF acquired in the United States in 11 western states (and in British Columbia by a U.S. resident) from January 1977 to January 2000. Exposure sites were in forested areas, at varying elevations, in mountainous regions (Cascade, Rocky Mountain, San Bernardino, and Sierra Nevada ranges) of the United States and Canada and in limestone caves in central Texas. Only 13 counties accounted for approximately 50% of all cases. Forty percent of the cases were not residents of the state where TBRF exposure occurred, including 7% from 11 states where TBRF is not endemic. TBRF is endemic in the United States and is a disease affecting travelers, who may return home with the disease to areas where physicians are not familiar with it.

Animals↗