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- Volume 93, Issue 1, July 2015
The American Journal of Tropical Medicine and Hygiene - Volume 93, Issue 1, July 2015
Volume 93, Issue 1, July 2015
- Images in Clinical Tropical Medicine
- Perspective Piece
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Yaws: 110 Years After Castellani's Discovery of Treponema pallidum subspecies pertenue
Pages: 4–6More LessAbstract.Yaws is a neglected infectious disease that affects mostly children and adolescents living in poor, rural communities in humid, tropical areas of Africa, southeast Asia, and the Pacific Islands. The etiological agent of yaws, Treponema pallidum subspecies pertenue (T. pertenue), was discovered by Aldo Castellani in 1905 shortly after Schaudinn and Hoffmann discovered the etiological agent of syphilis, T. pallidum subspecies pallidum. The discovery of T. pertenue enabled the development of animal models and the identification of an effective antibiotic treatment (i.e., penicillin) for yaws. A World Health Organization (WHO) mass treatment campaign from 1952 to 1964 reduced the global burden of yaws by 95%, but failed to eradicate this disease. Today, 110 years after Castellani's discovery of T. pertenue, yaws is again targeted for eradication. Recent advances in the treatment and diagnosis of yaws improve the likelihood of success this time. However, several challenges must be overcome to make the goal of yaws eradication attainable.
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- Articles
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Genetic Diversity of Venezuelan Alphaviruses and Circulation of a Venezuelan Equine Encephalitis Virus Subtype IAB Strain During an Interepizootic Period
Pages: 7–10More LessAbstract.Several species of alphaviruses have been previously described in the Americas, some of which are associated with encephalitis and others are associated with arthralgia. Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV) are endemic to Venezuela, with the former being responsible for major outbreaks of severe and often fatal disease in animals and humans. The aim of this study was to analyze the genetic diversity of Venezuelan alphaviruses isolated during two decades (1973–1999) of surveillance in northern Venezuela. Phylogenetic analysis indicated the circulation of a VEEV subtype IAB strain 8 years after the last reported outbreak. Thirteen strains within two subclades of South American lineage III of EEEV were also found in Venezuela. Considerable genetic variability was observed among Venezuelan Una virus strains, which were widely distributed among the clades. The first Venezuelan Mayaro sequence was also characterized.
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Emergence of a New Lineage of Cache Valley Virus (Bunyaviridae: Orthobunyavirus) in the Northeastern United States
Pages: 11–17More LessAbstract.Cache Valley virus (CVV; Family Bunyavidae, Genus Orthobunyavirus) is a mosquito-borne zoonosis that frequently infects humans and livestock in North and Central America. In the northeastern United States, CVV transmission is unpredictable from year-to-year and may derive from the periodic extinction and reintroduction of new virus strains into this region. To evaluate this possibility, we sequenced and analyzed numerous CVV isolates sampled in Connecticut during an 18-year period to determine how the virus population may change over time. Phylogenetic analyses showed the establishment of a new viral lineage during 2010 that became dominant by 2014 and appears to have originated from southern Mexico. CVV strains from Connecticut also grouped into numerous sub-clades within each lineage that included viruses from other U.S. states and Canada. We did not observe the development and stable persistence of local viral clades in Connecticut, which may reflect the episodic pattern of CVV transmission. Together, our data support the emergence of a new lineage of CVV in the northeastern United States and suggest extensive dispersal of viral strains in North America.
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Prospective Cohort Study with Active Surveillance for Fever in Four Dengue Endemic Countries in Latin America
Pages: 18–23More LessAbstract.To prepare for a Phase III dengue vaccine efficacy trial, 20 investigational sites were selected for this observational study to identify dengue infections in a closed cohort (N = 3,000 children 9–16 years of age). Of 255 acute febrile episodes experienced by 235 children, 50 (21.3%) were considered serologically probable dengue, and 18 (7.7%) were considered virologically confirmed (i.e., dengue NS1 antigen positive) dengue cases. Considering the disease-free and at-risk period from study start to onset of symptoms, the overall incidence density of acute febrile episodes was 17.7 per 100 person-years of follow-up, ranging from 15.3 in Colombia to 22.0 in Puerto Rico. This study showed that all sites were capable of capturing and following up acute febrile episodes within a specific timeframe among the established cohort and to detect dengue cases.
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Improving Dengue Virus Capture Rates in Humans and Vectors in Kamphaeng Phet Province, Thailand, Using an Enhanced Spatiotemporal Surveillance Strategy
Pages: 24–32More LessAbstract.Dengue is of public health importance in tropical and sub-tropical regions. Dengue virus (DENV) transmission dynamics was studied in Kamphaeng Phet Province, Thailand, using an enhanced spatiotemporal surveillance of 93 hospitalized subjects with confirmed dengue (initiates) and associated cluster individuals (associates) with entomologic sampling. A total of 438 associates were enrolled from 208 houses with household members with a history of fever, located within a 200-m radius of an initiate case. Of 409 associates, 86 (21%) had laboratory-confirmed DENV infection. A total of 63 (1.8%) of the 3,565 mosquitoes collected were dengue polymerase chain reaction positive (PCR+). There was a significant relationship between spatial proximity to the initiate case and likelihood of detecting DENV from associate cases and Aedes mosquitoes. The viral detection rate from human hosts and mosquito vectors in this study was higher than previously observed by the study team in the same geographic area using different methodologies. We propose that the sampling strategy used in this study could support surveillance of DENV transmission and vector interactions.
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Temperature and the Field Stability of a Dengue Rapid Diagnostic Test in the Tropics
Pages: 33–39More LessAbstract.The global incidence of dengue has increased significantly in recent decades, resulting in a large public health burden in tropical and subtropical countries. Dengue rapid diagnostic tests (RDTs) can provide accurate, rapid accessible diagnosis for patient management and may be easily used by health workers in rural areas. However, in dengue-endemic areas, ambient temperatures are often higher than manufacturer's recommendation. We therefore evaluated the effect of high temperature over time on the performance of one commonly used dengue RDT, the Standard Diagnostics Bioline Dengue Duo. RDTs were kept in five different conditions (at 4°C, 35°C, 45°C, 60°C, and at fluctuant ambient temperatures in a free-standing hut) for between 2 days and 2 years in the Lao People's Democratic Republic (PDR). RDTs were tested with four control sera (negative, dengue nonstructural protein 1 [NS1], anti-dengue immunoglobulin [Ig] M, and anti-dengue IgG positive). The RDTs had 100% consistency over the 2-year study, despite high temperatures, including in the hut in which temperatures exceeded the manufacturer's recommendations for 29% of time points. These data suggest that the diagnostic accuracy of the SD Bioline Dengue Duo RDT remains stable even after long-term storage at high temperatures. Therefore, use at such ambient temperatures in tropical areas should not jeopardize the dengue diagnostic outcome.
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Dengue Seroprevalence of Healthy Adults in Singapore: Serosurvey Among Blood Donors, 2009
Pages: 40–45More LessAbstract.Routine national notifications of dengue cases typically do not reflect the true dengue situation due to large proportion of unreported cases. Serosurveys, when conducted periodically, could shed light on the true dengue infections in the population. To determine the magnitude of dengue infections of the adult population in Singapore following the outbreak in 2007, we performed a cross-sectional study on blood donor samples from December 2009 to February 2010. The residual blood of 3,995 donors (aged 16–60 years) was screened for the presence of dengue-specific immunoglobulin G (IgG) and IgM using enzyme-linked immunosorbent assay (ELISA) kits. The age-weighted IgG prevalence of residents was 50.8% (N = 3,627, 95% confidence interval [CI] = 49.4–52.3%). Dengue IgG prevalence increased with age, with the lowest in 16–20 years age group (16.1%) and the highest in 56–60 years age group (86.6%). Plaque reduction neutralization test (PRNT) on samples of young resident adults (aged 16–30 years) revealed lower prevalence of neutralizing antibodies to each serotype, ranging from 5.4% to 20.3% compared with the older age groups. The level of exposure to dengue among the young adults is relatively low despite the endemicity of the disease in Singapore. It partially explains the population's susceptibility to explosive outbreaks and the high incidence rate among young adults.
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Evaluation of Nucleic Acid Stabilization Products for Ambient Temperature Shipping and Storage of Viral RNA and Antibody in a Dried Whole Blood Format
Pages: 46–53More LessAbstract.Loss of sample integrity during specimen transport can lead to false-negative diagnostic results. In an effort to improve upon the status quo, we used dengue as a model RNA virus to evaluate the stabilization of RNA and antibodies in three commercially available sample stabilization products: Whatman FTA Micro Cards (GE Healthcare Life Sciences, Pittsburgh, PA), DNAstāble Blood tubes (Biomātrica, San Diego, CA), and ViveST tubes (ViveBio, Alpharetta, GA). Both contrived and clinical dengue-positive specimens were stored on these products at ambient temperature or 37°C for up to 1 month. Antibody and viral RNA levels were measured by enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays, respectively, and compared with frozen unloaded controls. We observed reduced RNA and antibody levels between stabilized contrived samples and frozen controls at our earliest time point, and this was particularly pronounced for the FTA cards. However, despite some time and temperature dependent loss, a 94.6–97.3% agreement was observed between stabilized clinical specimens and their frozen controls for all products. Additional considerations such as cost, sample volume, matrix, and ease of use should inform any decision to incorporate sample stabilization products into a diagnostic testing workflow. We conclude that DNAstāble Blood and ViveST tubes are useful alternatives to traditional filter paper for ambient temperature shipment of clinical specimens for downstream molecular and serological testing.
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Rotavirus Group A Genotypes Detected Through Diarrheal Disease Surveillance in Haiti, 2012
Pages: 54–56More LessAbstract.Samples collected in 2012 through diarrheal disease surveillance in Haiti were tested for rotavirus by enzyme immunoassay and real time RT-PCR and positive samples were genotyped. The predominant genotypes were G1P[8] (29% prevalence) and G9P[8] (21%). The observed genotype prevalence was similar to that reported previously for other Caribbean countries.
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Factors Determining Water Treatment Behavior for the Prevention of Cholera in Chad
Pages: 57–65More LessAbstract.Cholera is a well-known and feared disease in developing countries, and is linked to high rates of morbidity and mortality. Contaminated drinking water and the lack of sufficient treatment are two of the key causes of high transmission rates. This article presents a representative health survey performed in Chad to inform future intervention strategies in the prevention and control of cholera. To identify critical psychological factors for behavior change, structured household interviews were administered to N = 1,017 primary caregivers, assessing their thoughts and attitudes toward household water treatment according to the Risk, Attitude, Norm, Ability, and Self-regulation model. The intervention potential for each factor was estimated by analyzing differences in means between groups of current performers and nonperformers of water treatment. Personal risk evaluation for diarrheal diseases and particularly for cholera was very low among the study population. Likewise, the perception of social norms was found to be rather unfavorable for water treatment behaviors. In addition, self-reported ability estimates (self-efficacy) revealed some potential for intervention. A mass radio campaign is proposed, using information and normative behavior change techniques, in combination with community meetings focused on targeting abilities and personal commitment to water treatment.
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Human Granulocytic Anaplasmosis in the United States from 2008 to 2012: A Summary of National Surveillance Data
Pages: 66–72More LessAbstract.Human granulocytic anaplasmosis is an acute, febrile illness transmitted by the ticks Ixodes scapularis and Ixodes pacificus in the United States. We present a summary of passive surveillance data for cases of anaplasmosis with onset during 2008–2012. The overall reported incidence rate (IR) was 6.3 cases per million person-years. Cases were reported from 38 states and from New York City, with the highest incidence in Minnesota (IR = 97), Wisconsin (IR = 79), and Rhode Island (IR = 51). Thirty-seven percent of cases were classified as confirmed, almost exclusively by polymerase chain reaction. The reported case fatality rate was 0.3% and the reported hospitalization rate was 31%. IRs, hospitalization rates, life-threatening complications, and case fatality rates increased with age group. The IR increased from 2008 to 2012 and the geographic range of reported cases of anaplasmosis appears to have increased since 2000–2007. Our findings are consistent with previous case series and recent reports of the expanding range of the tick vector I. scapularis.
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High Mortality Associated with Retreatment of Tuberculosis in a Clinic in Kampala, Uganda: A Retrospective Study
Pages: 73–75More LessAbstract.The World Health Organization recommends for tuberculosis retreatment a regimen of isoniazid (H), rifampicin (R), ethambutol (E), pyrazinamide (Z), and streptomycin (S) for 2 months, followed by H, R, E, and Z for 1 month and H, R, and E for 5 months. Using data from the National Tuberculosis and Leprosy Program registry, this study determined the long-term outcome under programmatic conditions of patients who were prescribed the retreatment regimen in Kampala, Uganda, between 1997 and 2003. Patients were traced to determine their vital status; 62% (234/377) patients were found dead. Having ≤ 2 treatment courses and not completing retreatment were associated with mortality in adjusted analyses.
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Human Fascioliasis: A Re-emerging Disease in Upper Egypt
Pages: 76–79More LessAbstract.In recent years, the number of humans infected with Fasciola has risen rapidly. Diagnosis is based mainly on detection of eggs in stool analysis. The rate of infection in Egypt is unknown. In this retrospective study, we describe 23 cases of hepatic fascioliasis, and only 2 of these cases showed eggs in stools. The symptoms of infection, such as pyrexia of unknown origin, epigastric pain, and abdominal distension, were suggestive. Imaging techniques, including abdominal ultrasonography and computed tomography, were very helpful in detecting hepatic changes. An indirect hemagglutination assay proved to be of value for diagnosis. Treatment using a 2-day triclabendazole regimen cured the infection and signs of hepatic involvement disappeared. Combining both imaging techniques and laboratory tests is essential for diagnosis of fascioliasis in the early stage.
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The First Step Toward Diagnosing Female Genital Schistosomiasis by Computer Image Analysis
Pages: 80–86More LessAbstract.Schistosoma haematobium causes female genital schistosomiasis (FGS), which is a poverty-related disease in sub-Saharan Africa. Furthermore, it is co-endemic with human immunodeficiency virus (HIV), and biopsies from genital lesions may expose the individual to increased risk of HIV infection. However, microscopy of urine and hematuria are nonspecific and insensitive predictors of FGS and gynecological investigation requires extensive training. Safe and affordable diagnostic methods are needed. We explore a novel method of diagnosing FGS using computer color analysis of colposcopic images. In a cross-sectional study on young women in an endemic area, we found strong associations between the output from the computer color analysis and both clinical diagnosis (odds ratio [OR] = 5.97, P < 0.001) and urine microscopy for schistosomiasis (OR = 3.52, P = 0.004). Finally, using latent class statistics, we estimate that the computer color analysis yields a sensitivity of 80.5% and a specificity of 66.2% for the diagnosis of FGS.
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Seasonal Transmission of Opisthorchis viverrini sensu lato and a Lecithodendriid Trematode Species in Bithynia siamensis goniomphalos Snails in Northeast Thailand
Pages: 87–93More LessAbstract.Seasonal changes play roles in the transmission success of fish-borne zoonotic trematodes (FZT). This study examined the seasonal transmission patterns of Opisthorchis viverrini sensu lato (s.l.) and a virgulate cercaria (family Lecithodendriidae) in the snail intermediate host, Bithynia siamensis goniomphalos in northeast Thailand. Snail samples were collected monthly during the rainy, cool, and hot seasons during 2012–2013 to determine the prevalence and intensity of larval trematode infections. The prevalence of O. viverrini s.l. varied significantly with season, being 0.31%, 1.05%, and 0.37% in the rainy, cool, and hot seasons, respectively (P < 0.05). Similarly, the prevalence of virgulate cercariae was 3.11%, 6.80%, and 1.64% in the rainy, cool, and hot seasons, respectively (P < 0.05). The intensity of larval trematode infections also varied between seasons and peaked in the hot season (P < 0.05) in both species. The snails infected with O. viverrini s.l. were significantly smaller (P < 0.05) and those infected with virgulate cercariae were significantly larger (P < 0.05) than uninfected snails. Seasonal variation and the different sizes of B. s. goniomphalos parasitized by O. viverrini s.l. and virgulate trematodes indicate complex host–parasite interactions with important implications for the epidemiology of O. viverrini s.l.
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Failure of Ivermectin per Rectum to Achieve Clinically Meaningful Serum Levels in Two Cases of Strongyloides Hyperinfection
Pages: 94–96More LessAbstract.Two cases of Strongyloides hyperinfection are presented. Ivermectin was initially administered orally and per rectum pending the availability of subcutaneous (SC) preparations. In neither case did rectal suppositories of ivermectin achieve clinically meaningful serum values. Clinicians should use SC preparations of ivermectin as early as possible in Strongyloides hyperinfection and dissemination.
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Information to Act: Household Characteristics are Predictors of Domestic Infestation with the Chagas Vector Triatoma dimidiata in Central America
Pages: 97–107More LessAbstract.The interruption of vectorial transmission of Chagas disease by Triatoma dimidiata in central America is a public health challenge that cannot be resolved by insecticide application alone. In this study, we collected information on previously known household risk factors for infestation in 11 villages and more than 2,000 houses in Guatemala, Honduras, and El Salvador, and we constructed multivariate models and used multimodel inference to evaluate their importance as predictors of infestation in the region. The models had moderate ability to predict infested houses (sensitivity, 0.32–0.54) and excellent ability to predict noninfested houses (specificity higher than 0.90). Predictive ability was improved by including random village effects and presence of signs of infestation (insect feces, eggs, and exuviae) as fixed effects. Multimodel inference results varied depending on factors included, but house wall materials (adobe, bajareque, and palopique) and signs of infestation were among the most important predictive factors. Reduced models were not supported suggesting that all factors contributed to predictions. Previous knowledge and information from this study show that we have evidence to prioritize rural households for improvement to prevent house infestation with Triatoma dimidiata in Central America. House improvement will most likely have other health co-benefits.
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Access to Care for Chagas Disease in the United States: A Health Systems Analysis
Pages: 108–113More LessAbstract.There are 300,000 estimated cases of Chagas disease in the United States but limited data on access to care. This study analyzed trends in access to care for Chagas disease in the United States and assessed the national and state barriers to access. Data on cases in blood donors and drug releases were obtained from the AABB (formerly American Association of Blood Banks) and U.S. Centers for Disease Control and Prevention (CDC), respectively. Semi-structured in-depth interviews were conducted with 30 key informants at the national level and in five states where treatment had been released. Interview responses were analyzed according to the health systems dimensions of regulation, financing, payment, organization, and persuasion. Data indicate that 1,908 cases were identified in the blood donation system from 2007 to 2013 and that CDC released 422 courses of benznidazole or nifurtimox during this period. The barriers to access at the national level include limited diagnostic and institutionalized referral and care processes, lack of financing for patient-care activities, and limited awareness and training among providers. This study demonstrates that access to treatment of Chagas disease in the United States is limited. The lack of licensing is only one of several barriers to access, highlighting the need for a health systems perspective when scaling up access to these essential medicines.
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Volumes & issues
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Volume 104 (2021)
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Volume 103 (2020)
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Volume 102 (2020)
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Volume 101 (2019)
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Volume 100 (2019)
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Volume 99 (2018)
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Volume 98 (2018)
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Volume 97 (2017)
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Volume 96 (2017)
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Volume 95 ([2016, 2017])
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Volume 94 (2016)
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Volume 93 (2015)
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Volume 92 (2015)
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Volume 91 (2014)
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Volume 90 (2014)
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Volume 89 (2013)
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Volume 88 (2013)
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Volume 87 (2012)
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Volume 86 (2012)
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Volume 85 (2011)
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Volume 84 (2011)
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Volume 83 (2010)
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Volume 82 (2010)
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Volume 81 (2009)
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Volume 80 (2009)
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Volume 79 (2008)
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Volume 78 (2008)
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Volume 77 (2007)
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Volume 76 (2007)
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Volume 75 (2006)
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Volume 74 (2006)
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Volume 73 (2005)
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Volume 72 (2005)
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Volume 71 (2004)
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Volume 70 (2004)
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Volume 69 (2003)
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Volume 68 (2003)
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Volume 67 (2002)
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Volume 66 (2002)
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Volume 65 (2001)
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Volume 64 (2001)
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Volume 63 (2000)
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Volume 62 (2000)
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Volume 61 (1999)
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Volume 60 (1999)
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Volume 59 (1998)
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Volume 58 (1998)
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Volume 57 (1997)
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Volume 56 (1997)
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Volume 55 (1996)
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Volume 54 (1996)
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Volume 53 (1995)
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Volume 52 (1995)
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Volume 51 (1994)
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Volume 50 (1994)
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Volume 49 (1993)
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Volume 48 (1993)
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Volume 47 (1992)
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Volume 46 (1992)
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Volume 45 (1991)
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Volume 44 (1991)
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Volume 43 (1990)
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Volume 42 (1990)
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Volume 41 (1989)
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Volume 40 (1989)
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Volume 39 (1988)
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Volume 38 (1988)
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Volume 37 (1987)
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Volume 36 (1987)
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Volume 35 (1986)
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Volume 34 (1985)
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Volume 33 (1984)
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Volume 32 (1983)
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Volume 31 (1982)
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Volume 30 (1981)
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Volume 29 (1980)
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Volume 28 (1979)
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Volume 27 (1978)
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Volume 26 (1977)
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Volume 25 (1976)
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Volume 24 (1975)
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Volume 23 (1974)
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Volume 22 (1973)
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Volume 21 (1972)
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Volume 20 (1971)
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Volume 19 (1970)
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Volume 18 (1969)
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Volume 17 (1968)
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Volume 16 (1967)
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Volume 15 (1966)
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Volume 14 (1965)
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Volume 13 (1964)
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Volume 12 (1963)
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Volume 11 (1962)
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Volume 10 (1961)
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Volume 9 (1960)
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Volume 8 (1959)
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Volume 7 (1958)
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Volume 6 (1957)
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Volume 5 (1956)
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Volume 4 (1955)
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Volume 3 (1954)
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Volume 2 (1953)
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Volume 1 (1952)
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Volume s1-31 (1951)
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Volume s1-30 (1950)
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Volume s1-29 (1949)
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Volume s1-28 (1948)
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Volume s1-27 (1947)
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Volume s1-26 (1946)
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Volume s1-25 (1945)
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Volume s1-24 (1944)
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Volume s1-23 (1943)
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Volume s1-22 (1942)
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Volume s1-21 (1941)
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Volume s1-20 (1940)
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Volume s1-19 (1939)
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Volume s1-18 (1938)
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Volume s1-17 (1937)
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Volume s1-16 (1936)
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Volume s1-15 (1935)
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Volume s1-14 (1934)
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Volume s1-13 (1933)
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Volume s1-12 (1932)
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Volume s1-11 (1931)
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Volume s1-10 (1930)
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Volume s1-9 (1929)
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Volume s1-8 (1928)
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Volume s1-7 (1927)
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Volume s1-6 (1926)
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Volume s1-5 (1925)
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Volume s1-4 (1924)
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Volume s1-3 (1923)
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Volume s1-2 (1922)
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Volume s1-1 (1921)