Surface waves and crustal structure on Mars.

We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.

Comparative analyses within Gyrodactylus (Platyhelminthes: Monogenea) mitochondrial genomes and conserved polymerase chain reaction primers for gyrodactylid mitochondrial DNA.

In this study, we describe the complete mitochondrial genomes of Gyrodactylus brachymystacis and Gyrodactylus parvae infecting rainbow trout (Oncorhynchus mykiss) and the invasive topmouth gudgeon (Pseudorasbora parva), respectively. The two circular genomes have a common genome organization found in other Gyrodactylus species. Comparative analyses of mitochondrial genomes from six Gyrodactylus species were carried out to determine base composition, codon usage, transfer RNA and ribosomal RNA genes, major non-coding regions, and nucleotide diversity within the genus. We also provide the first universal models of the secondary structures of rrnS and rrnL for this group thereby promoting utilization of these genetic markers. Universal primers provided herein can be used to obtain more mitochondrial information for pathogen identification and may reveal different levels of molecular phylogenetic inferences for this lineage.

Dawn arrives at Ceres: Exploration of a small, volatile-rich world.

On 6 March 2015, Dawn arrived at Ceres to find a dark, desiccated surface punctuated by small, bright areas. Parts of Ceres' surface are heavily cratered, but the largest expected craters are absent. Ceres appears gravitationally relaxed at only the longest wavelengths, implying a mechanically strong lithosphere with a weaker deep interior. Ceres' dry exterior displays hydroxylated silicates, including ammoniated clays of endogenous origin. The possibility of abundant volatiles at depth is supported by geomorphologic features such as flat crater floors with pits, lobate flows of materials, and a singular mountain that appears to be an extrusive cryovolcanic dome. On one occasion, Ceres temporarily interacted with the solar wind, producing a bow shock accelerating electrons to energies of tens of kilovolts.

Who is at high risk? A comparison of the seroprevalence of human immunodeficiency virus in pregnant women and a high risk group

To compare the seroprevalence of HIV in Jamaican pregnant women with that in substance abusers, two groups of antenatal patients were studied, one (A) attending a public hospital clinic and the other (B) attending private clinics. The HIV seroprevalence in the antenatal patients was compared with that in the substance abusers, group C, in 1996 and five years later in 2001. HIV antibody was determined by enzyme immunoassay. The HIV seroprevalence in group A more than doubled (1.6-3.8) in five-years, 1996-2001. There were no seropositives in group B. In group C, the seroprevalence rose from 2.08 in 1996 to 5.76 in 2001. There was indication that group A might no longer be considered [quot ]low risk[quot ], as there was no significant difference from group C in HIV seroprevalence in 1996 and 2001. The trend seen in this study is worthy of further investigation

Who is at high risk? A comparison of the seroprevalence of human immunodeficiency virus in pregnant women and a high risk group.

To compare the seroprevalence of HIV in Jamaican pregnant women with that in substance abusers, two groups of antenatal patients were studied, one (A) attending a public hospital clinic and the other (B) attending private clinics. The HIV seroprevalence in the antenatal patients was compared with that in the substance abusers, group C, in 1996 and five years later in 2001. HIV antibody was determined by enzyme immunoassay. The HIV seroprevalence in group A more than doubled (1.6%-3.8%) in five-years, 1996-2001. There were no seropositives in group B. In group C, the seroprevalence rose from 2.08% in 1996 to 5.76% in 2001. There was indication that group A might no longer be considered "low risk", as there was no significant difference from group C in HIV seroprevalence in 1996 and 2001. The trend seen in this study is worthy of further investigation.

Antibiotic susceptibility of Clostridium difficile isolates from adult patients at two Jamaican hospitals. Clinical and epidemiological implications.

The susceptibility of 39 toxin producing Clostridium difficile isolates from stools of hospitalized patients was determined, by disc diffusion, to six antibiotics. All but one isolate (toxin A negative) produced toxin A and toxin B. A wide variation in susceptibility to clindamycin, tetracycline and chloramphenicol was noted. Erythromycin and cotrimoxazole showed a clear-cut discrimination in resistance and susceptibility, while all isolates were sensitive to vancomycin. Erythromycin sensitive isolates demonstrated a significant association with diarrhoea (60.9%, 14/23, p < 0.001). These strains were predominantly found at the University Hospital of the West Indies (UHWI, 94.1%, 16/17). Strains resistant to erythromycin and clindamycin together were commonly found at the National Chest Hospital (NCH, 68.2%, 15/22). All erythromycin sensitive strains found at the NCH were from patients transferred to that hospital. These findings suggest that there is a common strain of C difficile (erythromycin resistant) at the NCH different from that found at the UHWI; the resistant pattern seen with isolates from the NCH was typical of toxigenic serogroup C strain and could be typed by the the disc diffusion method. Patients at the NCH who were colonized with either of the two strains of C difficile were likely to get diarrhoea, once there was suppression of the normal microflora by antibiotics and colonic overgrowth with C difficile.

Antibiotic susceptibility of Clostridium difficile isolates from adult patients at two Jamaican hospitals. Clinical and epidemiological implications

The susceptibility of 39 toxin producing Clostridium difficile isolates from stools of hospitalized patients was determined, by disc diffusion, to six antibiotics. All but one isolate (toxin A negative) produced toxin A and toxin B. A wide variation in susceptibility to clindamycin, tetracycline and chloramphenicol was noted. Erythromycin and cotrimoxazole showed a clear-cut discrimination in resistance and susceptibility, while all isolates were sensitive to vancomycin. Erythromycin sensitive isolates demonstrated a significant association with diarrhoea (60.9, 14/23, p < 0.001). These strains were predominantly found at the University Hospital of the West Indies (UHWI, 94.1, 16/17). Strains resistant to erythromycin and clindamycin together were commonly found at the National Chest Hospital (NCH, 68.2, 15/22). All erythromycin sensitive strains found at the NCH were from patients transferred to that hospital. These findings suggest that there is a common strain of C difficile (erythromycin resistant) at the NCH different from that found at the UHWI; the resistant pattern seen with isolates from the NCH was typical of toxigenic serogroup C strain and could be typed by the the disc diffusion method. Patients at the NCH who were colonized with either of the two strains of C difficile were likely to get diarrhoea, once there was suppression of the normal microflora by antibiotics and colonic overgrowth with C difficile.

Comparison of testing saliva and serum for detection of antibody to human immunodeficiency virus in Jamaica, West Indies.

BACKGROUND: In Jamaica the reported incidence of AIDS increased from 0.1/100000 in 1985 to 20.2/100000 in 1995. Here there is great reluctance to have voluntary blood testing and, indeed, any blood testing. Since only enzyme-linked immunoassay (EIA) was available for screening serum HIV-1 and 2 antibody, it was considered that a non-invasive saliva screening EIA could be an advantageous alternative. OBJECTIVE: this study was designed to evaluate the OraScreen HIV Rapid Test, a new, simple saliva screening EIA for anti-HIV-1&2 and to compare its sensitivity and specificity with a standard serum anti-HIV screening EIA in current use in Jamaica. STUDY DESIGN: specificity and sensitivity of HIV antibody assays were compared in matched serum and saliva samples obtained from 257 volunteers from a family planning clinic and from visa applicants, representing a low risk population (Group I), and from 52 volunteers known to be HIV infected (Group II). RESULTS: in Group I, 257 volunteers of unknown HIV status, one was positive for anti-HIV-1 in both serum and saliva. One other was seropositive but negative on saliva testing; confirmatory Western Blot (WB) testing on this serum was negative and this subject was tabulated as blood HIV negative. Fifty-one of the known seropositive volunteers (Group II) were saliva antibody positive. One saliva sample was inadequate and this individual was excluded from the study. Serum samples from three others in Group II were grossly haemolysed but their saliva samples were antibody positive. CONCLUSION: With the exclusion of one subject whose saliva sample was inadequate, the OraScreen HIV Rapid Test showed 100% specificity identifying 256/256 HIV antibody negative individuals, and 100% sensitivity by identifying 52/52 infected individuals as HIV antibody positive.

African hot spot volcanism: small-scale convection in the upper mantle beneath cratons.

Numerical models demonstrate that small-scale convection develops in the upper mantle beneath the transition of thick cratonic lithosphere and thin oceanic lithosphere. These models explain the location and geochemical characteristics of intraplate volcanos on the African and South American plates. They also explain the presence of relatively high seismic shear wave velocities (cold downwellings) in the mantle transition zone beneath the western margin of African cratons and the eastern margin of South American cratons. Small-scale, edge-driven convection is an alternative to plumes for explaining intraplate African and South American hot spot volcanism, and small-scale convection is consistent with mantle downwellings beneath the African and South American lithosphere.

Investigations of the epidemiology of infections with hepatitis A virus in Jamaica.

Between January 1995 and August 1998, a study was conducted to elucidate the epidemiology of hepatitis A virus (HAV) in Jamaica. Participants were recruited from six sites across the island. The potential risk factors for transmission which were studied included age of the individual, gender, residence (urban v. rural area), sanitary facilities (flush toilet v. pit) and source of domestic water (indoor plumbing v. other). There were 128 male subjects and 211 female, aged 3-90 years. The mean ages of the males and females were 24.9 and 25.6 years, respectively. The seroprevalence of HAV in the study population, estimated by ELISA, was 59.9%. Logistic regression indicated that age (P < 0.001) and source of domestic water (P = 0.006) were the major contributors to exposure to HAV. The rate of exposure to the virus was seen to increase with age. By the age of 10 years, 30% of children had been exposed, and almost 100% of the oldest subjects were seropositive. Rates of exposure to HAV were higher among households which had external sources of water, including standpipes, rivers and tanks, than those with indoor plumbing. Although the seroprevalence of HAV in Jamaica is similar to that seen in developing countries, the age-related pattern of exposure mirrors the pattern seen in developed countries.

Symptomatic and asymptomatic chlamydial non-gonococcal urethritis in Jamaica: the potential for HIV transmission.

To determine the contribution of Chlamydia trachomatis to non-gonococcal urethritis (NGU) in men attending sexually transmitted disease (STD) clinics in Jamaica we studied men with NGU (n=339), and control groups including asymptomatic men who were STD contacts (n=61), asymptomatic men who were not STD contacts (n=32) and men with gonococcal urethritis (GU) (n=61). Urethral specimens were examined for C. trachomatis and Neisseria gonorrhoeae. Serological tests for syphilis (STS) and HIV-1 infection were also performed. C. trachomatis accounted for 63% of cases of NGU but high prevalences were also found in asymptomatic STD contacts (59%), asymptomatic STD non-contacts (78%) and men with GU (48%). The prevalence of C. trachomatis in men with GU differed significantly from that in men with NGU and asymptomatic STD non-contacts (P<0.05). C. trachomatis infection in men with NGU was associated with multiple sex partners (71% vs 58%; chi2=4.78; odds ratio (OR)=1.76; P<0.05) and previous history of gonococcal infection (83% vs 42%; chi2=59.8; OR=6.8; P<0.0001). Concomitant infection with HIV-1 occurred in 5.2% of cases of NGU and 50% and 90%, respectively, of the HIV-positive men had chlamydia or reactive STS. As a cost effective strategy in the control of STD and HIV we recommend presumptive treatment for C. trachomatis in men seeking STD treatment in Jamaica.

Rubella susceptibility in Jamaican women, 1996.

The 1995 rubella outbreak in Jamaica indicated a need to survey the susceptibility rate in Jamaican antenatal women at risk. In this 1996 study, 389 women in the reproductive age group were investigated for rubella antibodies. In the public sector urban group (A), rubella susceptibility was 20.2%, while in a private sector urban clinic (B) practising routine rubella surveillance and recommending postpartum immunization in seronegatives, the susceptibility rate was 13.8%. The latter rate was significantly lower than that in the rural group (C) (35.9%; p < 0.001). The overall susceptibility rate was 21.3%. Rubella susceptibility has improved overall in women of childbearing age compared with levels in the prevaccine year of 1968. A significant thrust in rubella prevention will still be required before the next rubella epidemic in order to reduce the risk of congenital rubella syndrome.

Rubella susceptibility in Jamaican women, 1996

The 1995 rubella outbreak in Jamaica indicated a need to survey the susceptibility rate in Jamaican antenatal women at risk. In this 1996 study, 389 women in the reproductive age group were investigated for rubella antibodies. In the public sector urban group (A), rubella susceptibility was 20.2, while in a private sector urban clinic (B) practising routine rubella surveillance and recommending postpartum immunization in seronegatives, the susceptibility rate was 13.8. The latter rate was significantly lower than that in the rural group (C) (35.9; p < 0.001). The overall susceptibility rate was 21.3. Rubella susceptibility has improved overall in women of childbearing age compared with levels in the prevaccine year of 1968. A significant thrust in rubella prevention will still be required before the next rubella epidemic in order to reduce the risk of congenital rubella syndrome.

Evaluation of the MRL diagnostics dengue fever virus IgM capture ELISA and the PanBio Rapid Immunochromatographic Test for diagnosis of dengue fever in Jamaica.

We evaluated two new commercial dengue diagnostic tests, the MRL Diagnostics Dengue Fever Virus IgM Capture ELISA and the PanBio Rapid Immunochromatographic Test, on serum samples collected during a dengue epidemic in Jamaica. The MRL ELISA method correctly identified 98% (78 of 80) of the samples as dengue positive, while the PanBio test identified 100% (80 of 80). Both tests were 100% (20 samples of 20) specific.

High prevalence of genital Chlamydia trachomatis infection in women presenting in different clinical settings in Jamaica: implications for control strategies.

OBJECTIVE: To determine the prevalence of genital Chlamydia trachomatis infection and risk factors in women attending family planning, gynaecology, and sexually transmitted disease (STD) clinics in Jamaica. METHODS: Endocervical specimens from 645 women including 238 family planning, 170 gynaecology, and 237 STD clinic attendees were examined for C trachomatis using a direct fluorescence assay (DFA) and culture. Investigations were carried out for the presence of other STD pathogens and demographic, behavioural, historical, and clinical data recorded for each participant. RESULTS: The prevalence of C trachomatis infection was 35%, 47%, and 55% in family planning, gynaecology, and STD clinic clients, respectively. The performance of the DFA was comparable to that of culture in screening for C trachomatis. Logistic regression analysis revealed that the independent risk factors for C trachomatis infection were non-barrier contraceptive methods in family planning clients (OR = 2.1; 95% confidence interval (CI) = 1.2-3.9; p = 0.0110), cervical ectopy in gynaecology clients (OR = 3.9; 95% CI = 1.4-10.6; p = 0.0076) and concomitant Trichomonas vaginalis infection in STD clients (OR = 3.5; 95% CI = 1.8-6.8; p = 0.003). Age, number of sex partners, and reason for visit were not identified as risk factors for C trachomatis infection. CONCLUSIONS: Consistently high prevalence of C trachomatis infection occurs in Jamaican women. Universal screening or presumptive treatment should be evaluated as prevention and control measures for C trachomatis infection in this population where all women appear to be at risk.

The seroprevalence of hepatitis and retroviral infection in Jamaican haemodialysis patients.

63 haemodialysis (HD) patients and 63 age and gender matched controls were investigated for hepatitis B surface antigen (HbsAg) and antibodies to hepatitis B virus (anti-HBV), hepatitis C virus (anti-HCV), hepatitis D virus (anti-HDV), human immunodeficiency virus types 1 and 2 (anti-HIV-1 and 2) and human T-cell lymphotropic virus type-1 (anti-HTLV-1). The notable finding was an increase in hepatitis B markers, 34.9% in HD patients compared to 19.0% in controls (p < 0.02). The seroprevalence of anti-HCV (7.9%, p < 0.03) and anti-HTLV-1 (9.5%; p < 0.006) was also increased in the patients. Four of the five patients positive for anti-HCV were also seropositive for HBV. Anti-HIV and anti-HDV were not detectable in the HD patients in this study. The possibility of HTLV-1 being transmitted by organ transplantation is raised. The seropositivity rate for hepatitis B and C increased with duration on dialysis, but it is unlikely that it was related to the number of blood transfusions since 50% with no transfusion were HBV seropositive.

The seroprevalence of hepatitis and retroviral infection in Jamaican haemodialysis patients

63 haemodialysis (HD) patients and 63 age and gender matched controls were investigated for hepatitis B surface antigen (HbsAg) and antibodies to hepatitis B virus (anti-HBV), hepatitis C virus (anti-HCV), hepatitis D virus (anti-HDV), human immunodeficiency virus types 1 and 2 (anti-HIV-1 and 2) and human T-cell lymphotropic virus type-1 (anti-HTLV-1). The notable finding was an increase in hepatitis B markers, 34.9in HD patients compared to 19.0in controls (p < 0.02). The seroprevalence of anti-HCV (7.9, p < 0.03) and anti-HTLV-1 (9.5; p < 0.006) was also increased in the patients. Four of the five patients positive for anti-HCV were also seropositive for HBV. Anti-HIV and anti-HDV were not detectable in the HD patients in this study. The possibility of HTLV-1 being transmitted by organ transplantation is raised. The seropositivity rate for hepatitis B and C increased with duration on dialysis, but it is unlikely that it was related to the number of blood transfusions since 50with no transfusion were HBV seropositive.

Prevalence of viral and bacterial sexually transmitted pathogens in Jamaican pregnant women.

In this study we investigated the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, human immunodeficiency virus type I (HIV-I), human T cell lymphotropic virus type 1 (HTLV-1) and hepatitis B virus (HBV) infections in 200 pregnant women attending antenatal clinics at the University Hospital of the West Indies. 19% of the women had at least one pathogen: C. trachomatis was found in 16%, HTLV-1 in 2%, HIV-1, HBV and N. gonorrhoeae each in 0.5% C. trachomatis infection was more prevalent in women less than 20 years of age (31%) than in those 20 years and older (16%; OR = 0.43; chi 2 = 5.66; p < 0.05). The study demonstrates the need for identification of sexually transmitted pathogens in antenatal women for syndromic management of genital infections as part of the strategy for prevention and control of HIV/AIDS (acquired immunodeficiency syndrome) in Jamaica.

Prevalence of viral and bacterial sexually transmitted pathogens in Jamaican pregnant women

In this study we investigated the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum, human immunodeficiency virus type I (HIV-I), human T cell lymphotropic virus type 1 (HTLV-1) and hepatitis B virus (HBV) infections in 200 pregnant women attending antenatal clinics at the University Hospital of the West Indies. 19of the women had at least one pathogen: C. trachomatis was found in 16, HTLV-1 in 2, HIV-1, HBV and N. gonorrhoeae each in 0.5C. trachomatis infection was more prevalent in women less than 20 years of age (31) than in those 20 years and older (16; OR = 0.43; chi 2 = 5.66; p < 0.05). The study demonstrates the need for identification of sexually transmitted pathogens in antenatal women for syndromic management of genital infections as part of the strategy for prevention and control of HIV/AIDS (acquired immunodeficiency syndrome) in Jamaica.

Genital Chlamydia trachomatis (serotypes D-K) infection in Jamaican commercial street sex workers.

OBJECTIVES: To determine the prevalence of genital Chlamydia trachomatis infections in commercial street sex workers (CSSW) in Jamaica. METHODS: The prevalence of C trachomatis infection was determined in 129 Jamaican CSSW using the direct fluorescent antibody (DFA) method and the isolation techniques which utilise fluorescent and iodine staining of endocervical cytobrush specimens cultured in McCoy cells. The seroprevalence of C trachomatis in the CSSW was also compared with that in blood donors (n = 435), using the microimmunofluorescence (MIF) test. RESULTS: The DFA detected C trachomatis in 16% (21/129) of the specimens. The prevalence as determined by the iodine and fluorescein stained cultures was 24% (31/129) and 25% (33/129) respectively. The overall prevalence of current chlamydial infection detected by the isolation techniques used was 25% (33/129). As determined by the MIF test, a statistically significantly higher seroprevalence rate of C trachomatis (95%, 61/64) was found in CSSW compared with blood donors (53%, 229/435; OR 22.6; chi 2 = 49.8; p < 0.001). The prevalence of current infection in CSSW as indicated by the isolation of C trachomatis was not influenced by history of previous pelvic inflammatory disease (PID), sexually transmitted disease, or condom use. N gonorrhoeae (9%) and Candida albicans (7%) were found in comparatively low frequencies, while Trichomonas vaginalis (0%) was not found in specimens from the CSSW. CONCLUSIONS: A high seroprevalence rate and a high rate of current infection with C trachomatis occur in Jamaican CSSW. In order to control the spread and prevent the severe clinical complications and sequelae of C trachomatis infection, the diagnosis and treatment in such high risk groups such as CSSW should be optimised.

PIP: The prevalence of Chlamydia trachomatis infection was investigated in 129 commercial sex workers (CSWs) recruited on the streets in Kingston, Jamaica. The direct fluorescent antibody method detected C. trachomatis in endocervical cytobrush specimens from 21 women (16%). When the specimens were cultured, current chlamydial infection was detected by iodine staining in 31 (24%) and by monoclonal antibodies in 33 (25%). The microimmunofluorescence test for chlamydial antibodies was performed on clotted blood samples obtained from 64 CSWs and, as controls, 435 blood bank donors. A significantly higher seroprevalence rate was found among CSWs (95%) than blood donors (53%) (p 0.001). Among CSWs, the most common clinical manifestation of C. trachomatis infection was vaginal discharge. The presence of C. trachomatis infection was not related to previous history of pelvic inflammatory disease, sexually transmitted disease (STD), or condom use. Neisseria gonorrhoeae was isolated from 11 (9%) endocervical swabs. This study confirms the predominance of C. trachomatis among the bacterial causes of STDs in high-risk groups in Jamaica, and suggests a need for screening and treatment to control the spread and prevent the severe clinical sequelae of chlamydial infection.