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PubMed2005

Differences in the accuracy of human visuospatial memory after yaw and roll rotations.

Our ability to keep track of objects in the environment, even as we move, has been attributed to various cues including efference copies, vestibular signals, proprioception, and gravitational cues. However, the presence of some cues, such as gravity, may not be used to the same extent by different axes of motion (e.g., yaw vs. roll). We tested whether changes in gravitational cues can be used to improve visuospatial updating performance for yaw rotations as previously shown for roll. We found differences in updating for yaw and roll rotations in that yaw updating is not only associated with larger systematic errors but is also not facilitated by gravity in the same way as roll updating.

Adult↗

PubMed2000

Induction and impairment of saturated yaw and surge vection.

A flight simulator was used to investigate the perception of self-motion and visual scene motion during the induction of saturated 10 deg/sec yaw and 50 m/sec surge vection, and during subsequent impairment of saturated vection by inertial motions. The subjects (n = 5) did not perceive any self-acceleration or visual scene deceleration during the induction of saturated vection but perceived a rather sudden change in self-velocity and visual scene velocity. The mean group times to saturated vection were 3.0 sec for yaw and 2.7 sec for surge. Above certain inertial motion amplitudes, the subjects reported additional self-motion from the applied inertial motions while experiencing saturated vection. To impair saturated yaw vection, these amplitudes were 0.6 m/sec2, 0.4 m/sec2, 8 deg/sec2, and 5 deg/sec2, for surge, sway, roll and yaw motions, respectively. To impair saturated surge vection, these amplitudes were 0.6 m/sec2, 0.3 m/sec2, 5 deg/sec2, and 4 deg/sec2, respectively. The results indicate that saturated vection is more robust for translations than for rotations because the rotational inertial amplitudes were closer to the amplitudes at which the applied inertial motion was perceived than the translational inertial amplitudes.

Adult↗

PubMed2002

Eye movements to yaw, pitch, and roll about vertical and horizontal axes: adaptation and motion sickness.

BACKGROUND: In the search for parameters to predict motion sickness that can be measured in the laboratory, we performed a longitudinal investigation in aviators. Since the vestibular system is involved in the generation of motion sickness as well as eye movements, vestibulo-ocular reflex (VOR) parameters seemed relevant. We investigated three topics: 1) the effect of axis orientation and its orientation to gravity on the VOR; 2) changes in VOR parameters depending on flight experience; and 3) differences in VOR parameters in aircrew with high and low susceptibility to motion sickness. HYPOTHESIS: Nystagmus decay after angular velocity steps would be faster for non-susceptible and trained aviators. METHODS: We recorded eye movements evoked by angular on-axis velocity steps (+/- 90 degrees x S(-2), to and from 90 degrees x S(-1)) in yaw, pitch, and roll, about both the Earth vertical and Earth horizontal axes in 14 subjects with a low susceptibility to motion sickness. These data were compared with those of 10 subjects with a high susceptibility. RESULTS: Horizontal axis rotations are nauseogenic. We found that during (per) and post-condition, left- and rightward rotation responses were equal, and the orientation with respect to gravity did not alter the basic nystagmus decay, apart from a sinusoidal modulation. Moreover, pitch and roll rotations show equal nystagmus decays, significantly faster than for yaw; yaw and pitch peak velocities were equal and were larger than for roll. With regard to changes in VOR parameters depending on flight experience, we found that repeated vestibular stimulation reduced nystagmus decay as well as the otolith modulation. With respect to the changes in VOR parameters and motion sickness susceptibility, we found that subjects highly susceptible to motion sickness showed a slower decay of nystagmus with a larger peak velocity than less susceptible subjects. CONCLUSIONS: Group averages indicate a difference in eye movement parameters, only in yaw, depending on flight experience; and between subjects with low and high susceptibility to motion sickness. The involvement of the velocity storage mechanism as realized by an internal model is given as a plausible explanation.

Adaptation, Physiological↗

PubMed1984

On the epidemiology of yaws in African miners (1942).

Several points of interest arise from these unusual human yaws infections: (i) European miners contracted a treponemal infection from Africans with yaws and developed yaws; (ii) the infectious patients who started the minor epidemics in the outbreaks must have been relapses from prolonged latent early infections; (iii) the time taken for the treponemes, possibly only a few minutes, to penetrate the skin through a minor injury seemed to be less than six hours; (iv) transmission occurred only at the working rock face deep underground with a tropical climate, and not on the surface 1,630 metres above sea-level, where there were abundant opportunities; (v) the search for treponemes in the environment of the working place was restricted by the inability to culture the treponeme.

Adolescent↗

PubMed1993

Characterization of the skeletal manifestations of the treponemal disease yaws as a population phenomenon.

Documentation of the antiquity and tracking of the derivation of human treponemal diseases have been complicated by an inability to distinguish among these diseases biochemically, histologically, and immunologically. Skeletal impact, as a population phenomenon, has been suspected to vary sufficiently among the treponemal disorders to allow their differentiation. As yaws was the only treponemal infection present in pre-Spanish Guam, definitive characterization of this disease in terms of its skeletal impact has been possible. In the studies described herein, skeletons from a 500-year-before-present archaeological site at Gognga-Gun Beach were examined. Yaws-related periostitis was noted in 19% of skeletons, achieving full population "penetrance" by the second decade of life. While the cortical-surface striations were often quite subtle, general osseous expansion and saber shin deformity were noted in one-fourth of skeletons. Gummatous destruction was found in 15% of individuals and draining cloacae in 10%. Invariably, the presence of irregular/striated cortical-surface markings (along with saber shin deformity) and the absence of epiphyseal separation or dental abnormalities distinguished the lesions of yaws from those of syphilis.

Bone and Bones↗

PubMed1995

Treponemal disease revisited: skeletal discriminators for yaws, bejel, and venereal syphilis.

Assigning responsibility for the origins of treponemal disease has been complicated because of the (diagnostic) impreciseness of the historical written record and the inability to microbiologically distinguish among the treponematoses. Bedouin skeletal remains of individuals from the Negev area of Israel who had bejel, skeletons from the Todd human skeleton collection of individuals in whom syphilis was diagnosed, and skeletal remains from Guam of individuals who had yaws were analyzed to quantitatively assess their skeletal damage. The osseous reactions, although reproducible for each variety of treponemal disease, are not uniform among these skeletons. Examination of population frequency, demographics, character, and skeletal distribution of osseous treponemal damage in these skeletal sites provides clear, reproducible clues to the identity of the underlying treponematosis: bejel and yaws are common (> 20% according to skeletal findings) in the population. Syphilis and bejel usually spare the hands and feet. Yaws tends to be more polyostotic. Analysis of these parameters as population phenomena in pre-Columbian archeological sites should afford the opportunity to define the origins of the various treponemal disorders.

Archaeology↗

PubMedDate not supplied

Yaws in Ghana.

The final results of a three-year campaign against yaws in the Republic of Ghana, which was introduced in an attempt to reduce an unusually high prevalence, are summarized. The campaign started in January 1981 and officially ended in December 1983. Serious economic and technical constraints slowed the progress of work after the first year and reduced the total population covered. In spite of the shortcomings, the program provided penicillin treatment to 77,818 patients with active yaws (4.04% of those examined during the campaign) as well as chemoprophylaxis for an additional 1,556,360 contacts. The campaign staff compiled detailed information on the epidemiology of yaws in Ghana. A second attack phase using simple equipment and vehicles such as motorcycles and bicycles could be implemented with greater efficiency and could reduce costs.

Adolescent↗

PubMedDate not supplied

New technologies for use in the surveillance and control of yaws.

In the Republic of Ghana, treponemal antigen tests performed on finger-prick blood from patients with yaws proved to be as sensitive as those tests performed on whole sera, and this mode of collection was more economical and acceptable than venipuncture. Under field conditions, dark-field microscopic examination of suspect yaws lesions was difficult as compared with collection of serous exudate in heparinized capillary tubes examined later in a reference laboratory. Direct staining of lesion exudate fixed on microscope slides with fluorescein-conjugated human or mouse monoclonal antibody against Treponema pallidum was more sensitive than dark-field examination. However, these techniques could not distinguish between the early lesions of venereal syphilis and those of yaws. An equally sensitive technique used a cloned segment of the T. pallidum (Nichols strain) genome to detect homologous DNA in lesion exudate fixed on nitrocellulose filter paper. The fixation of lesion exudates on microscope slides or nitrocellulose papers may prove to be the easiest method of collecting and transporting such materials to reference laboratories.

Adolescent↗

PubMedDate not supplied

The effect of C3 depletion on resistance of hamsters to infection with the yaws spirochete.

The role of complement in humoral-mediated resistance to frambesial infection (yaws) needs to be defined. The level of serum C3 was reduced shortly after infection of hamsters with Treponema pallidum subspecies pertenue. Five weeks after frambesial infection, the serum C3 level began to increase and by week 7 no difference was detected between infected and uninfected hamsters. When C3 was depleted in hamsters by injection of 20 units of cobra venom factor (CoVF), two alterations in host resistance to frambesial infection occurred. Depletion of C3 abrogated the ability of immune serum to confer complete protection on normal hamsters against infection with the yaws spirochete. In all hamsters receiving immune serum but not CoVF, lesions failed to develop and lymph nodes weighed significantly less (P less than or equal to 0.1) than those of controls. Furthermore, no treponemes were detected in the lymph nodes of passively immunized animals. Second, depletion of C3 increased the susceptibility of hamsters to frambesial infection. The onset and progression of frambesial lesions were enhanced as compared with frambesial-infected hamsters not treated with CoVF. Finally, CoVF treatment did not reduce the ability of frambesia-immune hamsters cured of disease with penicillin to resist reinfection. These results demonstrate that complement influences the pathogenesis of yaws.

Animals↗

PubMed1979

Comparison of cardiolipin and treponemal tests in the serodiagnosis of yaws.

Results of the Veneral Disease Research Laboratory (VDRL), rapid plasma reagin (RPR), Treponema pallidum haemagglutination (TPHA), T. pallidum immobilisation (TPI), and fluorescent treponemal antibody absorption (FTA-ABS) tests on sera of 661 children from a region where yaws is hypoendemic are compared. For 107 (16.2%) out of 661 sera the FTA-ABS test was the only one showing reactivity; in these instances the test was weakly reactive (intensity of fluorescence scored as +) and the children had no history and no signs or symptoms of treponemal disease. A solitary, weakly reactive FTA-ABS test result seems to have no clinical significance in these cases. The FTA-ABS test can be used as a confirmatory test for yaws instead of the TPI test, if only the results of sera showing an intensity of fluorescence scored as ++ or more are considered to be positive. There appeared to be no significant differences in the results of the VDRL, RPR, and TPHA tests as screening tests for yaws when the TPI or FTA-ABS tests were used as reference tests.

Adolescent↗

PubMed1990

Early yaws: a light microscopic study.

This paper presents the light microscopic findings in biopsies of skin lesions from 45 patients, in whom a diagnosis of early yaws was suspected. In 27 cases typical light-microscopic features of yaws were observed, consisting of parakeratosis or crust containing exudate, marked acanthosis with widening and elongation of the rete ridges or pseudo-carcinomatous hyperplasia and spongiosis. Intraepidermal microabscesses consisting of polymorphonuclear leucocytes were frequently encountered. In a large majority a moderate to dense infiltrate was present, composed mainly of lymphocytes and plasma cells. Vascular changes consisted of only slight endothelial cell proliferation and thickening of vessel walls. Steiner staining revealed the presence of treponemes in the epidermis in 23 of 27 cases. Remarkably, clusters of treponemes were also seen in the papillary dermis in three out of 23 cases. Seven other cases were strongly suggestive of yaws. Other histopathological diagnoses were made in 6 patients, due to the simultaneous occurrence of other skin diseases. The remaining five specimens did not contain enough tissue to allow conclusions to be made.

Adolescent↗

PubMed2003

[Campaign to eradicate yaws on Santo Island, Vanuatu in 2001].

At the beginning of the 1960s a campaign was carried out to eradicate endemic trepanematosis in the South Pacific. During the year 2000, twenty cases of yaws were diagnosed on Santo Island in Vanuatu. Recrudescence of this disease was confirmed by a seroprevalence testing showing 20.9% positive VDRL in 273 serum tests. In view of these findings, the Health Minister in collaboration with the WHO office in Vanuatu undertook mass benzathine-benzylpenicilline treatment in the population of the Santo and Malo (SANMA) province. The objective was to treat at least 85% of the population. Treatment was administered to 36,414 of the 39,397 inhabitants identified in 587 villages during the campaign, i.e., 92.4%. Coverage varied from 87.6 to 97.3% depending on the zone. Positive VDRL was obtained in 96 of the 230 serum samples collected for suspicion of yaws. All documented cases of yaws were found in the southeastern part of the island. Treatment had a dramatic effect on lesions within 24 hours. Cooperation of the population and involvement of mobile units and primary health-care providers were key factors in the success of this campaign. Further action will include training of health care workers and improvement of sanitary conditions in villages. Seroprevalence testing to assess the effectiveness of this campaign is to be carried out in 2003.

Adolescent↗

PubMed1992

[Resurgence of yaws in Central African Republic. Role of the Pygmy population as a reservoir of the virus].

The authors present the results of a clinical (framboesia) and serological (TPHA and VDRL) investigation aimed at defining the reservoir of virus of yaws in the Lobaye area (southwest of CAR) out of which the disease spreads in spite of previous mass treatment campaigns. The Lobaye focus is still active because we found among the pediatric population under the age of 15 years, 5.6% contagious skin lesion and 19.6% VDRL+. In this area with contact between nomadic Pygmies and sedentary ethnic groups, the observed level of clinical and serological attacks suggested that the pygmie population, as previously described, makes up the principal focus of yaws. For every 1 case found through clinical examination, 3.5 cases VDRL+ and 4.8 cases TPHA+ are found through serological examination. This proportion indicates that clinical screening alone is not sufficient to evaluate the endemic yaws level in a population.

Adolescent↗

PubMed1956

Endemic syphilis and yaws.

Endemic syphilis and similar conditions are compared in this paper with yaws. Both are non-venereal and endemic, and they have very similar epidemiological characteristics. There is also considerable similarity in the clinical manifestations at the various stages of yaws and endemic syphilis, the differences that do appear being mainly due to different environmental and living conditions. No antigenic or immunogenic differences between syphilis and yaws have yet been demonstrated, and the sensitivity of both to penicillin is the same. Control measures for both diseases may be based on similar principles.The author considers the treponematoses to be closely related infections, and stresses the "unitarian" view put forward by various writers.

Environment↗

PubMedDate not supplied

Studies on a focus of yaws in the Santiago Basin, province of Esmeraldas, Ecuador.

A clinical and serological epidemiological study done on a yaws focus in the Santiago Basin area, province of Esmeraldas, showed a prevalence of 11.3% for active clinical lesions and a seropositivity of 94.9%. The Rio Santiago was hyperendemic for yaws (prevalence, 17.9%; seropositivity, 98.0%) while Rio Zapallito was found to be mesoendemic and the Rio Cayapas and Rio Onzoles hypoendemic. Active and latent evidence of yaws was found only in the black race. Children, ages 5-12 year, were found to have the highest incidence (55.8%) of clinical lesions, with the majority found on the legs (64.2%). Papilloma was the most prevalent lesion (55.4%). Mass treatment of the basin using benzathine penicillin G was done according to WHO recommendation.

Adolescent↗

PubMed1991

Yaws infection in Tanna, Vanuatu 1989.

Yaws has been resurgent in the island of Tanna in southern Vanatu in the 1980's. Screening, conducted in 1988 and in 1989 during a mass treatment program identified a total of 464 clinical cases from the population of 20,200, a rate of 23 per thousand. Most of these (82%) were under 15 years of age. Serology was performed on 286 of which 23% were VDRL positive. Primary care services had been hampered in controlling yaws by difficulties with transport, isolation, community resistance and the lack of skilled personel to diagnose yaws and arrange prophylactic treatment. A mass screening and treatment program was implemented in 1989 with 91.8% coverage. This program was designed to work in the context of primary health care and thus has enhanced the relationship between the health services and local villagers. The program was successfully integrated with other health activities including health education, treatment of other diseases and vector control.

Age Factors↗

PubMed1989

Yaws revisited.

An outbreak of yaws consisting of ten active cases in Baling is described. Yaws should be suspected and considered in the differential diagnosis of sores in the limbs of children living in rural areas. The clinical features of yaws are highlighted to help in the recognition of the condition for those unfamiliar with the condition.

Adolescent↗

PubMed1989

Nasal manifestations of yaws.

Yaws is an infectious, non-venereal disease of the tropical countries, which is caused by Treponema pertenue. Gangosa and goundou were seen commonly in cases of yaws in Africa, particularly in the early part of this century. After successful WHO mass treatment campaigns, these conditions are rarely seen now. A case of yaws with gangosa, goundou, and a nasopharyngeal carcinoma is presented here for its rarity.

Humans↗