bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic diversity and relationships among Venezuelan equine encephalitis virus field isolates from Colombia and Venezuela.
Authors: Moncayo A C , Medina G M , Kalvatchev Z , Brault A C , Barrera R , Boshell J , Ferro C , Freier J E , Navarro J C , Salas R , De Siger J , Vasquez C , Walder R , Weaver S C
Published: May 2017

During field studies of enzootic Venezuelan equine encephalitis (VEE) viruses associated with epizootic emergence, a large number of virus isolates were made in sylvatic foci of Venezuela and Colombia. To rapidly characterize these isolates, antigenic subtypes were determined by means of immunofluorescence and by single-strand conformational polymorphism (SSCP) analysis by use of an 856-bp fragment from the P62 gene, which we used to distinguish genetic variants. Representative isolates were sequenced to assess the sensitivity of SSCP to detect genetic differences. The SSCP analysis distinguished isolates differing by as little as 1 nucleotide; overall, differences of > or = 1 nucleotide were recognized 89% of the time, and the sensitivity to distinguish strains that differed by only 1 or 4 nucleotides was 17 and 57%, respectively. Phylogenetic analyses of representative sequences showed that all recent isolates from the Catatumbo region of western Venezuela and the middle Magdalena Valley of Colombia were closely related to epizootic subtype IAB and IC strains; strains from Yaracuy and Miranda States were more distantly related. Cocirculation of the same virus genotype in both Colombian and Venezuelan foci indicated that these viruses are readily transported between enzootic regions separated by > 300 km. The SSCP analysis appears to be a simple, fast, and relatively efficient method of screening VEE virus isolates to identify meaningful genetic variants.
Helminth infections are associated with protection from malaria-related acute renal failure and jaundice in Thailand.
Authors: Nacher M , Singhasivanon P , Silachamroon U , Treeprasertsuk S , Vannaphan S , Traore B , Gay F , Looareesuwan S
Published: May 2017

Following studies showing an association between helminth infections and protection from cerebral malaria, we compared 22 patients with malaria-associated acute renal failure with 157 patients with moderately severe malaria. Helminths were associated with protection from renal failure (adjusted odds ratio [AOR], 0.16 [0.03-0.85], P = 0.03). Helminth-infected controls were less likely to have jaundice (AOR, 0.39 [0.16-0.96], P = 0.04) or to have peripheral mature schizonts (AOR, 0.2 [0.07-0.62], P = 0.005) than controls without helminths. This suggested that preexisting helminth infections may have been protective by influencing sequestration and obstructive jaundice, 2 possible determinants of acute tubular necrosis.
Contribution of humoral immunity to the therapeutic response in falciparum malaria.
Authors: Mayxay M , Chotivanich K , Pukrittayakamee S , Newton P , Looareesuwan S , White N J
Published: May 2017

The contribution of humoral immunity to the therapeutic response in acute falciparum malaria was assessed in a case-control study. Forty adult Thai patients with acute falciparum malaria who had subsequent recrudescent infections and 40 patients matched for age, therapeutic regimen, and disease severity who were cured by Day 28 were studied. All cured patients had positive immunoglobulin (Ig) G to ring-infected erythrocyte surface antigen (RESA) in their admission plasma, compared with only 60% of patients who failed to respond to treatment (P < 0.001). The proportion of IgM-positive cases at admission was also higher in the successfully treated group than in the group with failure (70% versus 30%) (P < 0.001). The geometric mean (95% confidence interval) reciprocal IgG titer at admission was significantly higher in cured patients (187.0 [83.5-418.3]) compared with those who experienced treatment failure (11.6 [5.1-26.5]) (P < 0.001). The patients with uncomplicated malaria who were both IgG and IgM positive at admission had significantly shorter fever clearance times and lower admission parasitemia levels compared with those who were negative (P = 0.01 and P = 0.02, respectively). The median (range) in vitro parasite multiplication rate was significantly lower in cultures containing positive anti-RESA antibody plasma compared with those containing normal plasma (0.7 [0.1-3.5] versus 2.6 [0.1-12.1]; P < 0.001). These results suggest that antimalarial antibodies may play an important supportive role in the therapeutic response to antimalarial drugs during acute falciparum malaria.
Geographic information system-aided analysis of factors associated with the spatial distribution of Echinococcus multilocularis infections of foxes.
Authors: Staubach C , Thulke H H , Tackmann K , Hugh-Jones M , Conraths F J
Published: May 2017

To investigate the influence of environmental factors on the spatial epidemiology of infections with Echinococcus multilocularis, foxes were sampled in a focal endemic region in the Northwest of Brandenburg, Germany, and examined for infection by the parasite. The locations where foxes were obtained were recorded in a geographic information system database. Positions of infected and uninfected foxes were analyzed on the background of geographic vector data of water, settlements, streets, forests, crop, and pasture. Fox positions were allocated to different land-use classes by use of a Landsat Thematic Mapper (TM) satellite image. Infected foxes were more frequently shot near water, in areas of high soil humidity, and on pastures, suggesting that dryness may limit the tenacity of E. multilocularis oncospheres. Thus open landscapes with humid soil seem to be favorable for the life cycle of the parasite. In contrast, infected foxes were significantly underrepresented in forest areas.
Probable autochthonous Plasmodium vivax malaria transmission in Michigan: case report and epidemiological investigation.
Authors: Sunstrum J , Elliott L J , Barat L M , Walker E D , Zucker J R
Published: May 2017

In September 1995, a Michigan resident with no history of international travel was diagnosed with Plasmodium vivax infection, and local mosquito-borne transmission was suspected. An epidemiological investigation did not identify additional cases of local transmission, and there was no apparent link to the 12 imported malaria cases detected in the region. Potential sites of nighttime outdoor exposure included a campground in a swampy area, close to a racetrack frequented by international travelers, some of whom were known to come from countries with malaria transmission. Entomological investigation identified Anopheles spp. larvae and adults near the campsite. Summer temperatures 4.2 degrees C above average would have contributed to shortened maturation time of P. vivax within the insect vector, increasing the likelihood of infectivity. These investigations indicated that this patient probably acquired P. vivax infection through the bite of a locally infected Anopheles spp. mosquito. Physicians need to consider malaria as a possible cause of unexplained febrile illness, even in the absence of international travel, particularly during the summer months.
Molecular epidemiology of malaria in cameroon. IX. Characteristics of recrudescent and persistent Plasmodium falciparum infections after chloroquine or amodiaquine treatment in children.
Authors: Basco Leonardo K , Ndounga Mathieu , Keundjian Annick , Ringwald Pascal
Published: May 2017

In the absence of a firmly established gene responsible for chloroquine and amodiaquine resistance in Plasmodium falciparum, surveillance of resistance to these first-line drugs in Cameroon needs to be performed by in vivo or in vitro tests for drug resistance. These 2 methodological approaches to define drug resistance were shown to be complementary and concordant in a majority of cases at our study sites, but discordant results may be observed in a few cases, probably as a result of acquired immunity and low plasma drug levels. To further examine the nature of recrudescent and persistent parasitemia after treatment with chloroquine or amodiaquine, the clinical response of children aged < 5 years, presumably with insufficient immune response, was assessed, and the in vitro response of the corresponding isolates was determined if treatment or parasitological failure occurred. Genotyping of pretreatment and posttreatment isolates was performed by polymerase chain reaction to distinguish between recrudescence and reinfection. Plasma drug levels were measured at the time of therapeutic failure by high-performance liquid chromatography. All cases of therapeutic or parasitological failure observed on or before Day 14 were due to the persistence or recrudescence of the original parasite populations present before treatment, with or without selection and appearance of new populations. Most parasites were characterized by elevated 50% inhibitory concentrations for chloroquine and amodiaquine at the time of clinical or parasitological failure. In some children, recrudescence was explained by the absence of drug in the plasma. The simultaneous analysis of clinical and in vitro responses, plasma drug level measurement, and genotyping may yield results that may explain the reasons for therapeutic failure, help establish the threshold level for in vitro resistance, and provide a set of more accurate tools to describe the epidemiology of drug-resistant P. falciparum while awaiting for the identification of the chloroquine and amodiaquine resistance gene or genes.
Low-dose liposomal amphotericin B in refractory Indian visceral leishmaniasis: a multicenter study.
Authors: Sundar S , Jha T K , Thakur C P , Mishra M , Singh V R , Buffels R
Published: May 2017

In this randomized, double-blind, dose-ranging, multicenter trial, 84 patients with visceral leishmaniasis refractory to antimony therapy were administered liposomal amphotericin B (AmBisome) at cumulative doses of 3.75, 7.5, and 15.0 mg/kg for 5 consecutive days. Posttreatment apparent cure and definite cure were assessed at 2 weeks and 6 months after the end of therapy, respectively. Mild to moderate infusion-related fever and rigors were seen in 29 and 44% of patients, respectively. One patient each in the 3.75- and 7.5-mg groups had detectable parasites on splenic smear at posttreatment evaluation. At 6 months' follow-up, however, 2, 1, and 1 patients relapsed in the 3.75-, 7.5-, and 15.0-mg groups, resulting in definite cure rates of 89, 93, and 97%, respectively. There was no significant difference in the cure rates of the 3 groups. Low-dose liposomal amphotericin B given for 5 days can cure most patients with Indian kala-azar.
Random amplified polymorphic DNA technique for identification and differentiation of old world Leishmania species.
Authors: Ikram Guizani , Dellagi Koussay , IsmaÃ¯l Riadh Ben
Published: May 2017

The random amplified polymorphic DNA technique may be used to explore parasite DNA polymorphisms. We assessed its applicability to identification of Old World Leishmania species. A set of 6 random decamer primers (Al, A4, A5, A7, A10, and A15) was applied to a panel of DNA from 57 representatives of different Old World Leishmania species. The amplification profiles allowed discrimination among species belonging to different taxonomic complexes. Two criteria were used to analyze the profiles: the presence of consistent amplicons at the same electrophoretic position for isolates of the same species, and the presence of distinct amplicons for isolates of different species. Three primers--Al, A7 and A10--rendered such products.
Reactivity to bacterial, fungal, and parasite antigens in patients with lymphedema and elephantiasis.
Authors: Baird Jill B , Charles Jacky Louis , Streit Thomas G , Roberts Jacquelin M , Addiss David G , Lammie Patrick J
Published: May 2017

Both secondary infections and antifilarial immunity are thought to play roles in the development and progression of lymphedema. To investigate this issue, immune responses to a panel of bacterial, fungal, and parasite antigens were examined for women with lymphedema and elephantiasis (n = 28) and for women with no clinical evidence of lymphatic dysfunction who were either microfilaremic (Mf+, n = 23) or microfilaria- and filarial antigen-negative (Ag-, n = 24). The prevalence and intensity of delayed-type hypersensitivity (DTH) responses was similar for most recall antigens; for individual antigens, lymphedema patients were significantly more likely to be reactive only to Proteus. Lymphedema patients with a history of three or more attacks of adenolymphangitis in the last 18 months showed increased DTH reactivity to Trichophyton. Proliferative responses to fungal and bacterial antigens were similar for all three groups; however, antigen-negative women, independent of disease status, mounted greater responses to filarial antigen. In contrast, lymphedema patients had higher levels of antifilarial specific IgG1, IgG2, and IgG3 and higher IgG responses to streptolysin O than either Ag- or Mf+ women. In persons with lymphatic filariasis, immune reactivity is influenced by disease status as well as infection status.
Impact of the malaria control campaign (1993-1998) in the highlands of Madagascar: parasitological and entomological data.
Authors: Romi R , Razaiarimanga M C , Raharimanga R , Rakotondraibe E M , Ranaivo L H , Pietra V , Raveloson A , Majori G
Published: May 2017

Malaria transmission in the central highlands of Madagascar was interrupted in the 1960s by a national control program that used DDT indoor spraying and mass treatment with chloroquine. At the end of the 1980s in this region, epidemic malaria reappeared. Italian health authorities provided technical assistance to the National Malaria Control Program since the beginning of the resurgence of malaria in the central highlands. Yearly residual house spraying performed for 5 years (1993-1998) and the availability of antimalarial drugs reduced malaria transmission to very low levels, with improvement in parasitologic and entomologic indexes. A significant reduction of malaria prevalence was observed in the villages located at altitudes of 1,000-1,500 m, corresponding to the stratum of unstable malaria that was the main target of the antivector interventions. A significant reduction of malaria prevalence was also observed in the villages located at altitudes of 900-1,000 m, where malaria transmission is stable. The main vector Anopheles funestus was dramatically reduced in abundance and distribution in the sprayed areas.
Combined ultrasound and serologic screening for hepatic alveolar echinococcosis in central China.
Authors: Bartholomot Gitte , Vuitton Dominique A , Harraga Said , Shi Da Zhong , Giraudoux Patrick , Barnish Guy , Wang Yun Hai , MacPherson Calum N L , Craig Philip S
Published: May 2017

Alveolar echinococcosis (AE), caused by Echinococcus multilocularis, is a zoonotic helminthic disease that can mimic malignancy. In the 1970s, foci of the disease were found in central China. The aim of the present study was to estimate the prevalence of AE in humans in 2 districts of south Gansu Province, China, by use of ultrasound and Echinococcus serology. After answering an epidemiological questionnaire, 2,482 volunteers from 28 villages underwent ultrasound. Serology via enzyme-linked immunosorbent assay for antibody activity was performed on whole blood collected on filter paper in all subjects; on serum from subjects with an abnormal ultrasound image; and on randomly chosen subjects that either had no lesions or had atypical lesions. At least one (25.3%) abnormal ultrasound image was observed in 630 of the subjects screened. A typical lesion of progressive AE was found in 84 subjects (3.4%). Serologies were positive in 77 (96%) of 80 of patients who had lesions typical of progressive AE. Ultrasound is useful for screening for AE in endemic regions.
Parasitic load and histopathology of cutaneous lesions, lymph node, spleen, and liver from BALB/c and C57BL/6 mice infected with Leishmania mexicana.
Authors: Aguilar Torrentera Fabiola , Lambot Marie-Alexandra , Laman Jon D , Van Meurs Marjan , Kiss Robert , NoÃ«l Jean-Christophe , Carlier Yves
Published: May 2017

The course of infection, parasitic loads, and histopathology of cutaneous lesions, draining lymph node, spleen, and liver were compared in BALB/c and C57BL/6 mice over a period of 34 weeks after inoculation in footpad with promastigotes of a Leishmania mexicana reference strain. The results show that the primary footpad lesions first present a 12-week phase that develops similarly in both strains of mice. Thereafter, a cutaneous and visceral dissemination of L. mexicana parasites occurs in BALB/c mice; the latter experience an extensive breakdown of the lymphoid organ microarchitecture, whereas C57BL/6 mice succeed in eliminating the parasite infection from the lymph nodes but not from the primary cutaneous lesion, which does not heal. These results highlight marked differences between responses of key anatomical compartments controlling L. mexicana infection in BALB/c and C57BL/6 mice.
Asymptomatic human carriers of Leishmania chagasi.
Authors: Costa Carlos H N , Stewart Jay M , Gomes RÃ©gis B B , Garcez Lourdes M , Ramos PatrÃ­cia K S , Bozza Marcelo , Satoskar Abhay , Dissanayake Senarath , Santos Regina S , Silva Mauro R B , Shaw Jeffrey J , David John R , Maguire James H
Published: May 2017

In Brazil, programs based on elimination of infected dogs have not curtailed the spread of visceral leishmaniasis (VL), suggesting that other reservoirs of infection exist. Persons with active VL can infect the sand fly vector, but in endemic areas, persons with asymptomatic infections, whose infectivity to sand flies is unknown, are far more numerous. In this study, a polymerase chain reaction-based assay detected kinetoplast DNA of Leishmania chagasi in the blood of eight of 108 asymptomatic persons living with patients with recently diagnosed VL. These eight persons had low or unmeasurable levels of IgG antibodies to Leishmania, demonstrating the insensitivity of serology for subclinical infection. All eight persons had positive leishmanin skin test results, as did 70% of persons living in households of persons with active VL. Even if a small proportion of such asymptomatic persons are infective to sand flies, they represent a formidable reservoir of infection in endemic areas.
The detection of Mycobacterium leprae protein and carbohydrate antigens in skin and nerve from leprosy patients with type 1 (reversal) reactions.
Authors: Lockwood Diana N J , Colston M J , Khanolkar-Young S R
Published: May 2017

Type 1 (reversal) reactions are the most common immunological complications of leprosy. These episodes of delayed hypersensitivity produce severe local immunopathology and ultimately nerve damage. To date, the Mycobacterium leprae antigens associated with type 1 reactions have not been identified. Using monoclonal antibodies to defined protein and carbohydrate M. leprae epitopes (65, 35 and 28 kd and lipoarabinomannan [LAM]) in a two-step immunoperoxidase staining technique, M. leprae antigens were demonstrated in skin and nerve biopsies from patients in reversal reaction. Antigen presence and staining patterns were similar in skin and nerve lesions, implying that the pathological processes are similar in the two sites. Antigens were present both in macrophages and Schwann cells but also as a diffuse extracellular infiltrate associated with the inflammatory infiltrate. The 28-kd antigen was present most strongly and may be a potential candidate antigen for initiating type 1 reactions. LAM also stained strongly and persisted after treatment. The possible roles of LAM and 65 kd in the cellular events of type 1 reactions are discussed.
Evidence of Rickettsia typhi and the potential for murine typhus in Jayapura, Irian Jaya, Indonesia.
Authors: Richards Allen L , Rahardjo Eko , Rusjdi A Faisal , Kelly Daryl J , Dasch Gregory A , Church Cole J , Bangs Michael J
Published: May 2017

Murine typhus (etiologic agent: Rickettsia typhi) is endemic to Indonesia, especially on the highly populated island of Java. A survey of rodents from Irian Jaya, the eastern-most province of Indonesia, indicated striking geographic variation in risk factors associated with murine typhus. Murid rodents (n = 112) collected from two villages in the Arso district of northeastern Irian Jaya, were found to be free of ectoparasites normally associated with transmission of R. typhi (i.e., Xenopsylla cheopis). All rodents (n = 72) tested by enzyme-linked immunosorbent assay were negative for antibodies to R. typhi, whereas 12.5% (9/72) were positive for antibodies to Orienta tsutsugamushi. In contrast, both Rattus norvegicus and R. rattles (combined n = 87) from the harbor area of the provincial capital, Jayapura, were infested with flea ectoparasites. X. cheopis was found on 31 (35.6%) of the live-captured rodents. Serum samples from nine of 82 rodents contained antibodies reactive to R. typhi (11.0%). These data show for the first time that rodents exposed to R. typhi are well established in Jayapura, and that some of these rodents harbor fleas potentially capable of transmitting murine typhus and plague.
Short report: Positive correlation between rosetting and parasitemia in Plasmodium falciparum clinical isolates.
Authors: Rowe J Alexandra , Obiero Jack , Marsh Kevin , Raza Ahmed
Published: May 2017

Plasmodium falciparum isolates that form rosettes with uninfected red cells are associated with severe malaria in African children, although the mechanism by which rosetting contributes to severe disease is unknown. Here we have analyzed the relationship between rosetting and parasitemia in two samples of clinical isolates from children with malaria in Kilifi, Kenya. A consistent positive correlation was found between rosetting and parasitemia (Spearman's rank correlation coefficent p = 0.467, P < .001, n = 154, for 1993 study; p = .407, P < .001, n = 74, for 2000 study). Rosetting may enhance parasite growth and survival by facilitating invasion or promoting immune evasion, thus allowing higher parasitemia to develop and increasing the likelihood of severe malaria.
Short report: socioeconomic and seasonal variations of Helicobacter pylori infection in patients in Venezuela.
Authors: DomÃ­nguez-Bello MarÃ­a G , Beker Bernardo , Guelrud MoisÃ©s , Vivas Jorge , Peraza SimÃ³n , PÃ©rez MarÃ­a E , Pericchi Luis R
Published: May 2017

Infection by Helicobacter pylori is recognized as a risk factor for gastric cancer and peptic ulcer disease. Venezuela has regions with different gastric cancer risks; the Andean region has the highest gastric cancer mortality in the country. We performed a cross-sectional study on 357 patients who underwent endoscopy attending 2 private (n = 76) and one public hospital in Caracas, Venezuela (n = 215), and one public hospital in the Andes (n = 66) to determine H. pylori infection (by a rapid biopsy urease test and histology). The proportion of infected patients in Caracas was significantly higher in public hospitals (72%) than in private hospitals (46%; P = 0.00001), and there was no significant variation the Andes and Caracas (P = 0.7001). When analyzing the data from the public hospital in Caracas, we found that the frequency of infected patients was significantly higher during the rain (96%) than during the dry months (70%, P = 0.00000001). Differences in prevalence of infection in symptomatic patients was not related to the risk of gastric cancer but to socioeconomic differences. Rain-dependent factors that may be exacerbating the clinical activity of nonulcer dyspepsia in people infected with H. pylori deserve further study.
High prevalence of Brugia timori infection in the highland of Alor Island, Indonesia.
Authors: Supali Taniawati , Wibowo Herry , RÃ¼ckert Paul , Fischer Kerstin , Ismid Is S , Purnomo  , Djuardi Yenny , Fischer Peter
Published: May 2017

To identify areas endemic for Brugia timori infection, a field survey was carried out in 2001 on Alor, East Nusa Tenggara Timor, Indonesia. Elephantiasis was reported on this island by villagers as a major health problem. Bancroftian filariasis was detected in four villages in the coastal area, whereas B. timori was identified in four rice-farming villages. No mixed infections with both species were found. In the highland village Mainang (elevation = 880 m), 586 individuals were examined for B. timori infection and 157 (27%) microfilaria carriers were detected. The prevalence of microfilaremic individuals standardized by sex and age was 25%. The geometric mean microfilarial density of microfilaremic individuals was 138 microfilariae/ml. Among teenagers and adults, males tended to have a higher microfilarial prevalence than females. Microfilaria prevalence increased with age and a maximum was observed in the fifth decade of life. In infected individuals, the microfilarial density increased rapidly and high levels were observed in those individuals 11-20 years old. The highest microfilaria density was found in a 27-year-old woman (6,028 microfilariae/ml). Brugia timori on Alor was nocturnally periodic, but in patients with high parasite loads, a small number of microfilariae was also detected in the day blood. The disease rate was high and many persons reported a history of acute filarial attacks. Seventy-seven (13%) individuals showed lymphedema of the leg that occasionally presented severe elephantiasis. No hydrocele or genital lymphedema were observed. This study showed that B. timori infection is not restricted to the lowland and indicated that it might have a wider distribution in the lesser Sunda archipelago than previously assumed.
Epidemiology of amebiasis in a region of high incidence of amebic liver abscess in central Vietnam.
Authors: Blessmann Joerg , Van Linh Pham , Nu Phuong Anh Ton , Thi Hao Duong , Muller-Myhsok Bertram , Buss Heidrun , Tannich Egbert
Published: May 2017

The recent identification of Entamoeba dispar as a separate species, which is nonpathogenic for humans but morphologically indistinguishable from Entamoeba histolytica, has prompted the World Health Organization to recommend reinforced efforts for reassessment of the epidemiology of amebiasis and, in particular, of E. histolytica. In this regard, the distribution of amebic liver abscess (ALA) cases were analyzed in the province of Thua Thien HuÃ© (TT HuÃ©) in central Vietnam, a region known for its high incidence of invasive amebiasis. In addition, in a particular area of HuÃ© City, a parasitologic and seroepidemiologic survey was performed to identify possible risk factors for transmission of E. histolytica. Based on the analysis of hospital charts from April 1990 to April 1998, 2,031 cases of ALA were identified, indicating an ALA incidence of at least 21 per 100,000 inhabitants per year. Incidence varied substantially between the various districts of TT HuÃ© and directly correlated with population density. The risk for ALA was significantly higher in summer and was age and sex dependent because 95% of the cases were adults, of which more than 80% were males. There was no clustering of cases within households and recurrent cases of ALA occured more frequently than predicted in the study population. Despite the higher incidence of ALA in males, the parasitologic and seroepidemiologic survey revealed a significant higher infection rate for intestinal protozoon parasites, including E. histolytica in females. Besides level of education and access to a toilet or tapwater, use of river water was identified as an important risk factor for E. histolytica infection.
Large genetic distances among Aedes aegypti populations along the South Pacific coast of Mexico.
Authors: GarcÃ­a-Franco Francisco , MuÅ„oz Maria De Lourdes , Lozano-Fuentes Saul , Fernandez-Salas Ildefonso , Garcia-Rejon Julian , Beaty Barry J , Black William C
Published: May 2017

A population genetic analysis was conducted among 20 Aedes aegypti collections from 19 cities along the south Pacific coast in the Mexican states of Guerrero, Oaxaca, and Chiapas and in Coatepeque, Guatemala. Genetic variation was scored at 131 random amplified polymorphic DNA loci. The amount of genetic differentiation among collections was approximately 3 times as great as detected among collections in an earlier study in northeastern Mexico. Regression analysis of linear or road distances on linearized F(ST) indicated that collections are genetically isolated by distance. Cluster analysis failed to group collections in geographic proximity, and there was as much genetic variation among collections 60 km apart as there was among all collections (approximately 900-km range). The large genetic differentiation in southern Mexico reflects reduced gene flow among mosquitoes arising in a greater diversity of habitats and altitudes than exists among northeastern collections. It is likely that dispersal via human commerce in the northeast confounds patterns of natural gene flow.
A cost comparison of two malaria control methods in Kyunggi Province, Republic of Korea, using remote sensing and geographic information systems.
Authors: Claborn David M , Masuoka Penny M , Klein Terry A , Hooper Tomoko , Lee Arthur , Andre Richard G
Published: May 2017

A cost-comparison of two methods for the control of malaria in the Republic of Korea was performed. The cost of larviciding with methoprene granules was estimated at $93.48/hectare. The annual cost of providing chemoprophylaxis was estimated at $37.53/person. Remote sensing and geographic information systems were used to obtain estimates of the size of vector larval habitats around two U.S. Army camps, allowing an estimate of the cost of larviciding around each of the camps. This estimate was compared to the cost of providing chloroquine and primaquine chemoprophylaxis for the camp populations. Costs on each of the camps differed by the size of the larval habitats and the size of the at-risk population. These tools allow extrapolation of larval surveillance data to a regional scale while simultaneously providing site-specific cost analysis, thus reducing the cost and labor associated with vector surveillance over large areas.
Randomized comparison of low-dose versus standard-dose praziquantel therapy in treatment of urinary tract morbidity due to Schistosoma haema tobium infection.
Authors: King Charles H , Muchiri Eric M , Mungai Peter , Ouma John H , Kadzo Hilda , Magak Philip , Koech Davy K
Published: May 2017

At present, anthelmintic therapy with praziquantel at a dose of 40 mg/kg of body weight is the recommended treatment for control of urinary tract morbidity caused by Schistosoma haematobium. Although this standard regimen is effective, drug cost may represent a significant barrier to implementation of large-scale schistosomiasis control programs in developing areas. Previous comparison trials have established that low-dose (20-30 mg/kg) praziquantel regimens can effectively suppress the intensity of S. haematobium infection in endemic settings. However, the efficacy of these low-dose regimens in controlling infection-related morbidity has not been determined in a randomized field trial. The present random allocation study examined the relative efficacy of a 20 mg/kg dose versus a 40 mg/kg dose of praziquantel in control of hematuria and bladder and renal abnormalities associated with S. haematobium infection in an endemic area of Coast Province, Kenya. After a nine-month observation period, the results indicated an advantage to the standard 40 mg/kg praziquantel dose in terms of reduction of infection prevalence and hematuria after therapy (P < 0.01 and P < 0.005, respectively). However, the two treatment groups were equally effective in reducing structural urinary tract morbidity detected on ultrasound examination. We conclude that in certain settings, a 20 mg/kg dose of praziquantel may be sufficient in providing control of morbidity due to urinary schistosomiasis in population-based treatment programs.
Short report: Isolation and identification of Venezuelan equine encephalitis virus from a human in Panama.
Authors: Mangiafico Joseph A , Rossi Cindy A , Ludwig George V
Published: May 2017

Venezuelan equine encephalitis (VEE) virus was isolated from a febrile human in Panama. The patient became febrile approximately 10 days after returning from Gatun Lake in Panama. The virus was isolated from the acute phase serum and identified as VEE, subtype ID virus by monoclonal antibodies, and was confirmed by cross plaque-reduction neutralization tests.
Amebic infections due to the Entamoeba histolytica-Entamoeba dispar complex: a study of the incidence in a remote rural area of Ecuador.
Authors: Gatti Simonetta , Swierczynski Giovanni , Robinson Francisco , Anselmi Mariella , Corrales Javier , Moreira Juan , Montalvo Gregorio , Bruno Antonella , Maserati Roberta , Bisoffi Zeno , Scaglia Massimo
Published: May 2017

An epidemiologic field study was conducted in the village of BorbÃ²n in Esmeraldas province in northern Ecuador to compare different parasitologic methods in the diagnosis of infection with the Entamoeba histolytica/Entamoeba dispar complex. The results of two stool antigen detection assays (the Prospect Entamoeba histolytica microplate assay and the E. histolytica II assay) were compared with isoenzyme characterization of the amebic isolates. Nearly all (176 of 178, 98.9%) subjects were positive for intestinal parasites on direct microscopic examination, and cysts and/or vegetative forms morphologically consistent with the E. histolytica/E. dispar complex were recorded in 48 of 178 cases (27%). Culture in Robinson's medium was positive for amebic stocks in 89 (50%) of the 178 samples tested. Of the 37 isolates successfully stabilized, cloned, and characterized by zymodeme analysis, seven (18.9%) showed isoenzyme patterns of E. histolytica, whereas 26 (70.3%) showed patterns of E. dispar. The remaining four strains were identified as Entamoeba coli (three isolates; 8.1%) and Dientamoeba fragilis (one strain; 2.7%).The immunochromatographic tests showed different degrees of sensitivity and specificity when compared with isoenzyme characterization as the reference technique. The microplate assay, which does not discriminate between E. histolytica and E.dispar, showed a sensitivity of 54.5% and a specificity of 94% for both these amebic species. In contrast, the second-generation E. histolytica II test had a sensitivity of 14.3% and a specificity of 98.4% for E. histolytica sensu stricto. Our survey clearly demonstrated that more specific and sensitive diagnostic tests, such as stool antigen detection assays and isoenzyme analysis, are needed to establish the actual worldwide distribution of E. histolytica and E. dispar.
Predicting the prevalence of antibody to hepatitis C virus (HCV) in a community by the prevalence of elevated levels of alanine aminotransferase: a method to identify areas endemic for HCV.
Authors: Lu Sheng-Nan , Wang Jing-Houng , Kuo Yung-Kuang , Kuo Hsiu-Lin , Chen Tsung-Ming , Tung Hung-Da , Lee Chuan-Mo , Chen Shinn-Chern
Published: May 2017

To identify areas endemic for hepatitis C virus (HCV), we attempted to predict the prevalence of antibody to HCV (anti-HCV) in a community by the prevalence of elevated levels of alanine aminotransferase (ALT). The results of health examinations of 2,273 women > or = 40 years old in five townships in central Taiwan were analyzed. The overall prevalence of elevated ALT levels was 11.6%. A township (20.3%) and 10 villages were identified as having a high prevalence (17.9-40.0%) of elevated ALT levels. Five communities with variant rates of elevated ALT levels, which ranged from 8.0% to 27.3%, were selected for correlation with the prevalence of anti-HCV among adults (> or = 40 years old). The prevalence of anti-HCV, which ranged from 10.1% to 72.1%, were obtained by community screenings and/or hospital-based studies. The correlation equation used was the prevalence of anti-HCV (%) = 3.33 x (prevalence of elevated ALT levels (%) - 5.7%) (r2 = 0.94, P < 0.01). Using this method, areas endemic for HCV can be identified by determining the community prevalence of elevated ALT levels.
Growth characteristics of ChimeriVax-DEN2 vaccine virus in Aedes aegypti and Aedes albopictus mosquitoes.
Authors: Johnson Barbara W , Chambers Trudy V , Crabtree Mary B , Bhatt Tejal R , Guirakhoo Farshad , Monath Thomas P , Miller Barry R
Published: May 2017

The chimeric yellow fever (YF) 17D-dengue type 2 (ChimeriVax-DEN2) vaccine virus developed by Acambis, Inc. (Cambridge, MA) contains the prM and E genes of wild-type (wt) dengue 2 (DEN-2) (strain PUO-218) virus in the YF vaccine virus (strain 17D) backbone. The potential of ChimeriVax-DEN2 virus to infect and be transmitted by Aedes aegypti, the principal DEN and YF virus mosquito vector, and Aedes albopictus, a species that occurs in areas of active transmission of YF and DEN viruses, was evaluated. Mosquitoes were intrathoracically (IT) inoculated with virus or were fed a virus-laden blood meal, and the replication kinetics of ChimeriVax-DEN2 were compared with the wt DEN-2 and YF 17D vaccine viruses. Replication of YF 17D virus is attenuated in cultured Ae. albopictus C6/36 mosquito cells and in Ae. aegypti and Ae. albopictus mosquitoes. Growth of ChimeriVax-DEN2 virus similarly was restricted in C6/36 cells and in mosquitoes. ChimeriVax-DEN2 replicated in 56% of IT inoculated Ae. aegypti, and virus disseminated to head tissue in 36%, with a mean viral titer of 1.8 log10 PFU/mosquito. Of mosquitoes, 16% of Ae. aegypti and 24% of Ae. albopictus were infected 14 days after a blood meal containing ChimeriVax-DEN2, but virus did not disseminate to head tissue. In contrast, DEN-2 replicated in all IT inoculated and orally infected Ae. aegypti (mean titer 5.5 log10 PFU/mosquito), and virus disseminated to head tissue in 95%. Of Ae. albopictus, 84% were infected after a blood meal containing DEN-2 virus; dissemination occurred in 36%. Replication of ChimeriVax-DEN2 virus in mosquitoes corresponded to that of YF 17D vaccine virus, which is restricted in its ability to infect and replicate in mosquitoes. Therefore, transmission of ChimeriVax-DEN2 virus by vector mosquitoes is unlikely.
The importance of leptospirosis in Southeast Asia.
Authors: Laras Kanti , Cao Bao Van , Bounlu Khanthong , Nguyen Thi Kim Tien , Olson James G , Thongchanh Sisouk , Tran Nguyen Van Anh , Hoang Kim Loan , Punjabi Narain , Ha Ba Khiem , Ung Sam An , Insisiengmay Sithat , Watts Douglas M , Beecham H James , Corwin Andrew L
Published: May 2017

The importance of leptospirosis in Southeast Asia was assessed in conjunction with other studies supported by the U.S. Naval Medical Research Unit No. 2 (US NAMRU-2), Jakarta, Republic of Indonesia. These included studies of hospital-based, acute clinical jaundice in Indonesia, Lao PDR, and Socialist Republic of Vietnam; nonmalarial fever in Indonesia; and hemorrhagic fever in Cambodia. Background prevalence estimates of leptospiral infection were obtained by a cross-sectional, community-based study in Lao PDR. Laboratory testing methods involved serology, microscopic agglutination test, and reverse-transcriptase polymerase chain reaction. Suggestive evidence of recent leptospiral infections was detected in 17%, 13%, and 3% of patients selected on the basis of non-hepatitis A through E jaundice, nonmalarial fever, and hemorrhagic fever (in the absence of acute, dengue viral infections). Leptospiral IgG antibody, reflective of prior infections, was detected in 37% of human sera, collected in Lao PDR. The predominant leptospiral serogroups identified from cases with clinical jaundice were Hurstbridge, Bataviae, and Icterohaemorrhagiae tonkini LT 96 69. Among the nonmalarial febrile cases, Bataviae was the most frequently recognized serogroup. Pyrogenes and Hurstbridge were the principal serogroups among the hemorrhagic fever case subjects. These findings further attest to the relative importance of clinical leptospirosis in Southeast Asia. The wide spectrum of clinical signs and symptoms associated with probable, acute, leptospiral infections contributes to the potential of significant underreporting.
Failure of national guidelines to diagnose uncomplicated malaria in Bangladesh.
Authors: Faiz M A , Yunus Emran Bin , Rahman M Ridwanur , Hossain M Amir , Pang Lorrin W , Rahman M Ekhlasur , Bhuiyan S N
Published: May 2017

During the mid 1990s, national guidelines were established in accordance with World Health Organization recommendations for the diagnosis of uncomplicated malaria in Bangladesh. Based on simple clinical and epidemiologic criteria these guidelines were designed to be applied outside of tertiary care centers where microscopy was not feasible. We evaluated the positive predictive value (PPV) of these criteria using microscopic slide examinations as the gold standard in 684 subjects diagnosed and treated for malaria, sampling from eight subdistrict centers. The PPV for malaria was 32% with 19% for falciparum and 14% for Plasmodium vivax. Medical officers assigned to the study also gave their own clinical impression of whether cases could have been malaria. With the additional criteria of a medical officers' diagnosis, the PPV increased negligibly to 37% with 23% and 14% for falciparum and vivax, respectively. Since the PPV of diagnosis is low and cannot be improved on clinical grounds alone, we recommend the incorporation of laboratory diagnosis. This is especially important as we detect resistance to the first-line therapy chloroquine and require more expensive, potentially more toxic, regimens.
Short report: seasonal pattern of respiratory syncytial virus in a region with a tropical climate in southeastern Brazil.
Authors: Checon Rita Elizabeth , Siqueira Marilda M , Lugon Ana Kelly , Portes Silvana , Dietze Reynaldo
Published: May 2017

Among acute respiratory infections (ARIs), respiratory syncytial virus (RSV) is an important pathogen, especially in infants and preschool children. This study focused on RSV epidemiology in a region of southeastern Brazil with a tropical climate. A total of 406 nasopharyngeal secretion samples were taken from children less than five years of age with ARIs. Of these, 114 (28%) were RSV-positive. These samples were found in all age groups, but showed a higher prevalence in newborns. Infection with RSV was identified in 10 of the 12 months of the study period, but the majority (88.5%) of cases occurred from late summer to mid-fall.
Prevalence and incidence density of Mycobacterium leprae and Trypanosoma cruzi infections within a population of wild nine-banded armadillos.
Authors: Paige Christopher F , Scholl Daniel T , Truman Richard W
Published: May 2017

A total of 415 wild 9-banded armadillos from the East Atchafalaya River Levee (Point Coupee, LA) were collected over 4 years to estimate the incidence and prevalence of Mycobacterium leprae and Trypanosoma cruzi and to discern any relationship between the 2 agents. M. leprae infections were maintained at a high steady prevalence rate year to year averaging 19%. T. cruzi antibody prevalence remained relatively low, averaging 3.9%, and varied markedly between years. Prevalence rates were independent, with only 3 armadillos coinfected with both agents. M. leprae incidence density ranged from 0.47 to 3.5 cases per 1,000 animal-days, depending on case definition, confirming active intense transmission of M. leprae among armadillos. No incident T. cruzi cases were found. These infections seem to occur independently and may be used in comparisons to understand better factors that may influence transmission of these agents.
An observational clinic-based study of diarrheal illness in deployed United States military personnel in Thailand: presentation and outcome of Campylobacter infection.
Authors: Sanders J W , Isenbarger D W , Walz S E , Pang L W , Scott D A , Tamminga C , Oyofo B A , Hewitson W C , Sanchez J L , Pitarangsi C , Echeverria P , Tribble D R
Published: May 2017

Campylobacter is a leading cause of traveler's diarrhea in Thailand. Since resistance to quinolones is high among Campylobacter isolates, empiric therapy with quinolones for traveler's diarrhea may be ineffective in this region. We conducted an observational study among 169 U.S. military personnel with acute diarrhea and compared their microbiologic findings to those of 77 asymptomatic personnel deployed to Thailand in May 1998. Of 146 pathogenic bacterial isolates, the most common were nontyphoidal Salmonella (n = 31), enterotoxigenic Escherichia coli (n = 24), and C. jejuni/coli (n = 23). Campylobacter was strongly associated with disease (odds ratio = 5.9; 95% confidence interval = 1.3-37.3), with a more severe clinical presentation, and with a reduced functional ability at presentation (P = 0.02). In vitro resistance to ciprofloxacin was observed in 96% of the Campylobacter isolates. Sub-optimal treatment response to ciprofloxacin was observed in 17% of the cases of Campylobacter infection versus 6% due to other causes. These results highlight the importance of Campylobacter as a cause of severe traveler's diarrhea in Thailand and illustrates the ongoing problem with antibiotic-resistant strains and associated treatment problems.
Gambian children successfully treated with chloroquine can harbor and transmit Plasmodium falciparum gametocytes carrying resistance genes.
Authors: Sutherland Colin J , Alloueche Ali , Curtis Jill , Drakeley Chris J , Ord Rosalynn , Duraisingh Manoj , Greenwood Brian M , Pinder Margaret , Warhurst David , Targett Geoffrey A T
Published: May 2017

Polymorphisms in two genes of Plasmodium falciparum (P. falciparum multidrug resistance 1 [pfmdr1] and P. falciparum chloroquine [CQ] resistance transporter [pfcrt]) are associated with CQ treatment failure. We found significant linkage disequilibrium between these loci among isolates from symptomatic Gambian children (P = 0.026) and strong selection for the resistance-associated alleles pfmdr1-86Tyr and pfcrt-76Thr in children with persistent or re-emerging P. falciparum trophozoites during post-treatment follow-up (P = 1.9 x 10(-7)). Therefore, this genotype is characteristic of resistant infections among our study population. Since the long-term public health impact of parasites carrying such resistant genotypes depends upon their transmissibility, we examined the prevalence of pfmdr1-86Tyr and pfcrt-76Thr among Gambian children harboring sexual stage parasites during post-treatment follow-up. Gametocytes that emerged after successful treatment with CQ were significantly more likely to be of this genotype than were those emerging after other treatments (P = 4.83 x 10(-4)), and were infective to Anopheles mosquitoes. Therapeutic success may thus be accompanied by public health failure as cured children pass resistance genes on to mosquitoes at an enhanced rate.
Impact of preseason treatment on incidence of falciparum malaria and parasite density at a site for testing malaria vaccines in Bandiagara, Mali.
Authors: Coulibaly Drissa , Diallo Dapa A , Thera Mahamadou A , Dicko Alassane , Guindo Ando B , KonÃ© Abdoulaye K , Cissoko Yacouba , Coulibaly Seydou , DjimdÃ© Abdoulaye , Lyke Kirsten , Doumbo Ogobara K , Plowe Christopher V
Published: May 2017

Treating malaria before immunizing has been standard in malaria vaccine field trials. To assess the impact of this practice on subsequent infection and disease incidence, we conducted a randomized cohort study in Bandiagara, Mali. Subjects received a treatment dose of sulfadoxine-pyrimethamine (SP) or no treatment at the beginning of the transmission season. Cumulative and age-specific incidence of clinical episodes was similar between the 2 groups, but SP treatment delayed the median time to first clinical episode from 38.5 to 68 days, and after this initial period of protection, disease incidence in the SP group quickly surpassed the incidence in the untreated group. Parasite densities during disease episodes were lower in the SP group. SP was chosen as the drug for initial parasite clearance for the following reasons: 1) it has been used in previous vaccine trials; 2) our studies have found it to have >99% efficacy in treating uncomplicated malaria in Mali compared to 85-90% efficacy for chloroquine in this area; 3) SP is the approved second-line antimalarial agent in Mali; and 4) its single-dose regimen ensures compliance when treatment is directly observed.