The American Journal of Tropical Medicine and Hygiene - Online First

The CYD-TDV vaccine is licensed in multiple endemic countries based on vaccine efficacy (VE) against symptomatic, virologically confirmed dengue demonstrated in two phase 3 trials (CYD14, 2- to 14-year-olds, Asia; CYD15, 9- to 16-year-olds, Latin America). 50% plaque reduction neutralization test (PRNT50) titers at baseline and month 13 (post-vaccination) were associated with VE and may enable bridging VE to adults. Two phase 2 trials of CYD-TDV measured baseline and month 13 PRNT50 titers: CYD22 (9- to 45-year-olds, Vietnam) and CYD47 (18- to 45-year-olds, India). 50% plaque reduction neutralization test distributions were compared between age cohorts, and four versions of an epidemiological bridging method were used to estimate VE against any serotype (dengue virus [DENV]-Any) and against each serotype over 25 months post first vaccination in a hypothetical CYD14 + CYD15 18- to 45-year-old cohort (bridging population 1) and in the actual CYD47 18- to 45-year-old cohort (bridging population 2). Baseline and month 13 geometric mean PRNT50 titers to each serotype were significantly greater in 18- to 45-year-olds than 9- to 16-year-olds for all comparisons. The four methods estimated VE against DENV-Any at 75.3–86.0% (95% CIs spanning 52.5–100%) for bridging population 1 and 68.4–77.5% (95% CIs spanning 42.3–88.5%) for bridging population 2. The vaccine efficacy against serotype 1, 2, 3, and 4 was estimated at 56.9–76.9%, 68.3–85.8%, 91.4–95.0%, and 93.2–100% (bridging population 1) and 44.5–66.9%, 53.2–69.2%, 79.8–92.0%, and 90.6–95.0% (bridging population 2), respectively; thus, CYD-TDV would likely confer improved efficacy in adults than 9- to 16-year-olds. Using the same methods, we predicted VE against hospitalized DENV-Any over 72 months of follow-up, with estimates 59.1–73.5% (95% CIs spanning 40.9–92.2%) for bridging population 1 and 50.9–65.9% (95% CIs spanning 38.1–82.1%) for bridging population 2.

Endemic transmission of measles has been reestablished in Venezuela, and outbreaks of diphtheria remain ongoing across Latin America (LA). Hence, a large cross-sectional population-based serosurveillance study was conducted on Bonaire, one of the Dutch Leeward Antilles, to assess specific age and population groups at risk. Participants (aged 0–90 years) donated a blood sample and completed a questionnaire (n = 1,129). Antibodies against measles and diphtheria were tested using bead-based multiplex immunoassays. Our data revealed that immunity against measles is suboptimal, especially for those aged less than 5 years from Suriname, Aruba, and former Dutch Antilles (SADA), and adolescents from LA; and against diphtheria for persons aged more than 30 years, particularly among females and residents from SADA and LA. As refugees arrive persistently, health authorities on the Dutch Leeward Antilles should be on alert to detect early cases and prevent subsequent transmission. Ultimately, there is an urgent need for serosurveillance studies in the Caribbean region.

Hepatitis E virus (HEV) infection is associated with a high fatality rate among pregnant women, and gestational complications have been reported among pregnant women infected with hepatitis A virus (HAV). The aim of this study was to determine the seroprevalence of HAV and HEV infections among pregnant women in Haiti. We stratified the population (n = 1,307) between West and non-West regions. Specimens were tested for total HAV antibody (anti-HAV), and IgM and IgG HEV antibody (anti-HEV). Overall, 96.8% pregnant women were positive for total anti-HAV, 10.3% for IgG anti-HEV, and 0.3% for IgM anti-HEV. The prevalence of IgG anti-HEV in the non-West region (12.3%) was significantly greater than that in the West region (5.3%) (P < 0.0001). Most pregnant women in Haiti had evidence of past exposure and immunity to HAV. The non-West region had a higher prevalence of HEV. Improvement in water and sanitation will help in the prevention and control of these infections in Haiti.

Cryptosporidium is a parasite that causes watery diarrhea among both children and adults. However, because many physicians do not routinely ask for Cryptosporidium diagnostic test, cryptosporidiosis prevalence is likely underestimated. The current study investigated the prevalence of cryptosporidiosis among children admitted to the hospital with gastrointestinal symptoms. Stool sample was collected from each child and subjected to routine microbiological culture. Cryptosporidium presence was tested by three different methods: RT-PCR, quick antigen, and microscopic examination with acid-fast staining. Each positive specimen was further tested with BioFire FilmArray Multiplex PCR (bioMérieux SA, France) to determine that Cryptosporidium is the only pathogen in the sample. Demographic and epidemiological data were collected from the patients’ medical records. Of 291 patient stool samples, nine were positive for Cryptosporidium hominis or Cryptosporidium parvum. The average age of the nine Cryptosporidium-positive cases was 2.3 years, lower than the average age of the study population (4.2 years). Of the positive cases, 66.7% were Arabs and 33.3% were Jews. The main complaint of children with Cryptosporidium was diarrhea. Regarding the laboratory methods for Cryptosporidium identification, of the positive samples, 100% (9/9) were identified by RT-PCR, 88% (8/9) were positive by antigen test, and only 67% (6/9) were positive by microscopic examination with acid-fast staining. Because of the low incidence of Cryptosporidium among patients in our facility, the prevalence of cryptosporidiosis still cannot be established. Nevertheless, among the other pathogens found in stool samples, Cryptosporidium is the second leading cause of hospitalization due to gastrointestinal disease in children in our area.

Japanese encephalitis virus (JEV) is the most common cause of viral encephalitis in Asia, and it is increasingly a global public health concern because of its recent geographic expansion. Although commercial vaccines are available and used in some endemic countries, JEV continues to cause illness, with more than 60,000 cases reported annually. To develop a reproducible positive control antibody useable in diagnosis of JEV infections, murine hybridomas were developed from mice inoculated with a combination of IXIARO JEV vaccine and JEV domain III of the envelope protein (E-DIII). Monoclonal antibodies (MAbs) were characterized for their ability to neutralize virus in vitro. Monoclonal antibody 17BD3-2 was found to be JEV specific and highly neutralizing, with a plaque reduction neutralization test (PRNT)90 endpoint titer of 1.25 μg/mL. The functional epitopes were mapped using virus neutralization escape variants to amino acid residues S309, K312, and G333 in E-DIII. This MAb may be substituted for human immune sera used as a positive control in PRNT for distribution to public health laboratories worldwide in potential future outbreaks of JEV.

Schistosomiasis is a blood parasitic disease caused by trematode parasites of the genus Schistosoma. Schistosoma mansoni is one of the main contributors of the disease and 90% of the global burden of schistosomiasis is in Africa. Mass drug administration (MDA) has been implemented to reduce the disease burden in endemic areas. Because of MDA, the diagnostic sensitivity and specificity for classical diagnostic tests are reduced. In any disease situation, diagnosis is vital in determining asymptomatic, concurrent, current, new, and reinfection cases to evaluate the efficacy of any control program. We have evaluated the positive infection for S. mansoni from filtered urine samples collected from Zambian school children after MDA using loop-mediated isothermal amplification (LAMP) and compared its sensitivity and specificity with polymerase chain reaction (PCR). One hundred eleven urine samples collected from school children aged between 7 and 15 years from Siavonga district in southern Zambia were evaluated by PCR and LAMP for DNA extracted by two different protocols (filter-based versus crude extraction). The infection prevalence was 77% with PCR and almost 94% with mansoni-LAMP. Also, LAMP detected 16% (Qiagen extraction) and 10% (LAMP-Procedure for Ultra Rapid Extraction) more positive S. mansoni infection than PCR. We have demonstrated the efficacy of LAMP in a laboratory setup after MDA. The possible inclusion of LAMP as a field-based point-of-care test for surveillance can provide reliable prevalence of schistosomiasis after MDA and help in determining the efficacy of a control program.

Arboviral diseases are responsible for a high burden of disease in humans, and a significant part of disease risk reduction efforts relies on vector control methods. The elimination of potential breeding sites for the mosquito vectors and a higher level of literacy by the populations at risk could present a sustainable and environmentally friendly solution. This review aims to assess the efficacy of educational interventions for arboviral diseases on knowledge and self-reported behavior. A systematic literature search was performed using Cochrane, EMBASE, Global Health, and PubMed. References of articles retrieved were searched manually for further studies. Critical appraisal of the selected articles was performed using the Effective Public Health Practice Project tool, and studies with a control group were further assessed through the Cochrane’s risk of bias tool. A summary narrative of the results and a meta-analysis was conducted. Fourteen studies fulfilling the inclusion criteria were analyzed. Overall, there was an increase in knowledge and in self-reported adoption of protective measures. No effect was found using solely printed material. A meta-analysis was performed separately for the two outcomes measured, which produced a mean standardized difference of 1.86 (95% CI: 1.33–2.39) in knowledge scores compared with the control groups. Regarding the self-reported protective behavior, the results show a summary value of odds ratio of 5.23 (95% CI: 3.09–7.36). Most of the educational interventions had a positive impact on knowledge and self-reported adoption of protective measures. More research producing stronger evidence and evaluating long-term impact is needed.

Chagas disease is caused by the protozoan Trypanosoma cruzi. This disease is distributed in 21 Latin American countries, where it is mostly vector-borne. In Brazil, there are 68 triatomine species. To date, the epidemiological surveys indicate that the state of São Paulo presents 11 species of triatomines, and most of these species have already been collected in a home environment and found to be infected with T. cruzi. Problems in correctly identifying species can lead to incorrect panorama of distribution of Chagas disease vectors. Thus, we developed an identification key for the triatomines of the state of São Paulo, based on cytogenetic data. With the exception of Panstrongylus diasi that does not present cytogenetic data available in the literature, all species were differentiated by cytogenetic characteristics. We emphasize the importance of using this key as a simple and objective tool in the entoepidemiological surveys conducted by the vector control programs.

We report an unusual case of paragonimiasis in a Nepali patient presenting with massive pericardial effusion and pericardial tamponade. The patient reported neither the consumption of crabs or crayfish nor the consumption of wild animal meat, which are the usual sources of infection. It is suspected that the source of infection was instead the ingestion of raw live slugs as part of a traditional medicine treatment.

Cutaneous leishmaniasis (CL) remains one of the world’s most prevalent neglected diseases, particularly in developing countries. Identification of the involved Leishmania species is an important step in the diagnosis and case management process. In this study, we tested simple, rapid, and highly sensitive loop-mediated isothermal amplification (LAMP) assays for Leishmania DNA species-specific detection from cutaneous lesions. Two LAMP assays, targeting cysteine protease B (cpb) gene, were developed to detect and identify Leishmania major and Leishmania tropica species. Loop-mediated isothermal amplification specificity was examined using DNA samples from other Leishmania species and Trypanosoma species. No cross-reactions were detected. The developed LAMP assays exhibited sensitivity with a detection limit of 20 fg and 200 fg for L. major and L. tropica, respectively. Both tests were applied on clinical samples of CL suspected patients living in endemic Tunisian regions and compared with kinetoplast DNA quantitative PCR (qPCR), microscopic, and conventional cpb-based polymerase chain reaction (PCR) assays. Our LAMP tests were able to discriminate between L. major and L. tropica species and showed a sensitivity of 84% and a specificity of 100%. However, when compared with the performance of the diagnostic tests with latent class analysis (LCA), our LAMP assays show a sensitivity of 100%. These assays can be used as a first-line molecular test for early diagnosis and prompt management of CL cases in public health programs.