Research and Reports in Tropical Medicine最新文献

Loa loa is originally a restricted filarial worm from central Africa and some west African countries. However, numerous imported cases are being reported throughout the world due to human movement. Traditionally, its diagnosis is based on identification of microfilariae in the peripheral blood or the passage of the adult worm under the conjunctiva. However, few patients have microfilariae in their peripheral blood, while the majority of infected people are amicrofilaremic (without microfilariae in their blood), despite clinical symptoms suggesting L. loa infection. This situation suggests that diagnoses based on the presence of microfilariae in the blood or the ocular passage of an adult worm, are not sensitive. Therefore, it seems necessary to search for biomarkers to remedy this situation. Furthermore, L. loa is a major obstacle in the control of other filarial worms in areas where these filariae are co-endemic. To develop a diagnostic tool based on a biomarker, several approaches have been considered using antibodies, antigens or nucleic acid detection. However, none of the diagnostic techniques in loiasis based on biomarkers has reached the point of care as have microscopic detection of microfilariae or observation of ocular passage of a worm.

Purpose: Although Cambodia has made significant progress toward lowering the under-five mortality rate since 2000, diarrhea still accounts for 6% of the total number of these deaths. A vast majority of these deaths is preventable. In this study, we sought to examine diarrheal knowledge and preventative behaviors of caregivers of children under the age of 5 years, to determine caregiver factors associated with knowledge and behavior scores.

Patients and methods: This was a cross-sectional household-level study conducted in two floating villages on the Tonle Sap Lake, Cambodia between January and February 2014. Caregivers of children under 5 years of age in the villages of Steung Trov and Moat Khla were asked 31 true or false questions to assess their knowledge of diarrhea. They also filled out a questionnaire to assess diarrhea preventative behaviors (DPBs). Comparison of mean scores to categorical caregiver variables was performed using one-way ANOVA analysis. Spearman's rank correlation was applied to identify the relationship between the knowledge and preventative behavior scores and independent quantitative variables.

Results: A total of 101 caregivers of 161 children under 5 years of age were interviewed. The majority of them (85.1%) was classified as having good knowledge and scored >80% on the assessment. Those with Khmer ethnicity (mean=28.10) scored significantly higher than those with Vietnamese ethnicity (mean 26.00; p=0.004). Older age was correlated with higher knowledge scores (ρ=0.2260; p=0.023) and DPB scores (ρ=0.2320; p=0.019). Significant differences were found between the DPB score and ethnicity, educational background, and wealth (p<0.01).

Conclusion: Although the majority of caregivers had high diarrheal knowledge scores, preventative behaviors for diarrhea as assessed by this study were poor among almost all study participants. Vietnamese, wealthier, older, and more educated participants had better prevention scores. Future interventions in this remote region may benefit from these data as a guide to determine which specific preventative behaviors should be targeted.

Following the London declaration on neglected tropical diseases (NTDs) in 2012 and inspired by the WHO 2020 roadmap to control or eliminate NTDs, the Global Programme to Eliminate Lymphatic Filariasis (GPELF) intensified preventive chemotherapy and management of morbidity as the two main strategies to enhance progress towards the elimination of lymphatic filariasis (LF). This paper focuses on current perspectives of mass drug administration (MDA) towards the elimination of LF. The goal of MDA is to reduce the density of parasites circulating in the blood of infected persons and the intensity of infection in communities to levels where transmission is no longer sustainable by the mosquito vector. Three drugs, diethylcarbamazine, albendazole, and ivermectin are currently available for LF treatment, and their effectiveness and relative safety have opened the possibility of treating the entire population at risk. Currently, almost all LF endemic countries rely on the single-dose two-drug regimen recommended by the GPELF to achieve elimination. The 4th WHO report on NTDs has indicated that considerable progress has been made towards elimination of LF in some countries while acknowledging some challenges. In this review, we conclude that the 2020 elimination goal can be achieved if issues pertaining to the drug distribution, health system and implementation challenges are addressed.

Mansonellosis is a filarial disease caused by three species of filarial (nematode) parasites (Mansonella perstans, Mansonella streptocerca, and Mansonella ozzardi) that use humans as their main definitive hosts. These parasites are transmitted from person to person by bloodsucking females from two families of flies (Diptera). Biting midges (Ceratopogonidae) transmit all three species of Mansonella, but blackflies (Simuliidae) are also known to play a role in the transmission of M. ozzardi in parts of Latin America. M. perstans and M. streptocerca are endemic in western, eastern, and central Africa, and M. perstans is also present in the neotropical region from equatorial Brazil to the Caribbean coast. M. ozzardi has a patchy distribution in Latin America and the Caribbean. Mansonellosis infections are thought to have little pathogenicity and to be almost always asymptomatic, but occasionally causing itching, joint pains, enlarged lymph glands, and vague abdominal symptoms. In Brazil, M. ozzardi infections are also associated with corneal lesions. Diagnosis is usually performed by detecting microfilariae in peripheral blood or skin without any periodicity. There is no standard treatment at present for mansonellosis. The combination therapy of diethylcarbamazine plus mebendazole for M. perstans microfilaremia is presently one of the most widely used, but the use of ivermectin has also been proven to be very effective against microfilariae. Recently, doxycycline has shown excellent efficacy and safety when used as an antimicrobial against endosymbiotic Wolbachia bacteria harbored by some strains of M. perstans and M. ozzardi. Diethylcarbamazine and ivermectin have been used effectively to treat M. streptocerca infection. There are at present no estimates of the disease burden caused by mansonellosis, and thus its importance to many global health professionals and policy makers is presently limited to how it can interfere with diagnostic tools used in modern filarial disease control and elimination programs aimed at other species of filariae.

Background: Activation of immune cells by malaria infection induces the secretion of cytokines and the synthesis of other inflammatory mediators. This study compared the cytokine levels and leukocyte count between malaria-infected peripheral and placental blood of pregnant women before delivery and postpartum. The cytokines assessed include interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4), interleukin-6 (IL-6) and interleukin-10 (IL-10).

Materials and methods: The subjects comprised 144 malaria-infected pregnant women and 60 malaria-infected women at post-partum stage (for placental blood collection). Others were 60 malaria-uninfected pregnant women and 40 malaria-uninfected women at postpartum stage (for placental blood collection). Forty malaria-infected and 40 malaria-uninfected nonpregnant women served as control subjects. The test groups were asymptomatic, and the control groups were apparently healthy subjects. All were aged between 17 and 44 years. Ethical approval for the study was obtained at Abia State University Teaching Hospital and Living Word Mission Hospital, Aba. Informed consent was obtained from the participants. Blood samples were aseptically collected initially from the maternal peripheral circulation and from the placenta on delivery, and tested for HIV and malaria using standard methods. IFN-γ, TNF-α, IL-4, IL-6 and IL-10 were measured by enzyme-linked immunosorbent assay technique. Kruskal-Wallis test was used for comparison of the groups.

Results: IFN-γ was significantly higher in the peripheral than in placental blood (P=0.001). IL-4 and IL-10 were significantly lower in the peripheral than in placental blood (P=0.001 and P=0.004, respectively). The total leukocytes, neutrophils and lymphocyte counts were significantly higher in the placenta than in peripheral blood (P=0.001), and the mixed differential count was significantly higher in the placenta than in peripheral blood (P=0.012).

Conclusion: This study has shown that the cytokine levels and leukocyte counts may differ between the peripheral and placental blood of the same women. Therefore, measurement of parameters in the peripheral circulation may not always reflect the levels in the placental blood for the assessment of immune cellular response at the materno-fetal interface.

Background: To explore the use of azithromycin-chloroquine (AZCQ) for the treatment of malaria, we conducted double-blind, randomized, non-inferiority studies in India, Colombia, and Suriname comparing the combination of azithromycin 1 g and chloroquine (CQ) 600 mg base once daily (QD) for 3 days versus atovaquone-proguanil (AP) or chloroquine plus sulfadoxine-pyrimethamine (SPCQ) in adults with acute uncomplicated Plasmodium falciparum malaria.

Methods: Patients were hospitalized until three documented negative blood smears and followed through Day 42. The primary end point was parasitologic cure at Day 28.

Results: In India, parasite clearance rates were 84% and 94% for AZCQ and SPCQ, respectively (95% confidence interval [CI] for the difference: -22.6, 0.8). In Colombia and Suriname, parasite clearance rates were 57% and 99% for AZCQ and AP, respectively (95% CI: -52, -32). A subsequent open-label, non-comparative third study using a 2 g dose of azithromycin and 600 mg of CQ in India and Colombia resulted in an overall efficacy rate of 97%.

Conclusion: In India, Colombia, and Suriname, 1 g azithromycin with CQ QD for 3 days was inferior to established comparator agents. An improved response rate was observed when the dose of azithromycin was increased to 2 g.

Scrub typhus is an acute febrile illness in the "tsutsugamushi triangle", transmitted by chiggers that can be treated effectively if detected early. Laboratory testing, including molecular and serological assays, is needed for confirming the diagnosis, especially in the absence of the pathognomonic eschar. In this review, factors that play a role in disease occurrence and clinical clues for diagnosis, in addition to risk factors contributing to disease severity, including mortality, are discussed in detail. Moreover, issues related to diagnostic assays, treatment, and mixed infections are also enumerated and described.

Background: One of the specific targets of Directly Observed Treatment, Short-course detailed in the updated Global Plan (2011-2015) was to achieve a treatment success rate of 87% by 2015. This strategy was introduced to Ethiopia in 1995 to reach full coverage in 2005; however, by 2009, treatment had not been as successful as expected.

Objective: This study was conducted to determine treatment success rate and identify risk factors for tuberculosis (TB) treatment outcomes in North Shoa Administrative Zone, Amhara Regional State, Ethiopia.

Methods: A retrospective cohort study was conducted on all TB patients (739) who registered for TB treatment from September 1, 2012 to August 31, 2014 at public hospitals in North Shoa Administrative Zone, Ethiopia. Data were gathered by using a pretested structured medical record checklist. Four data collectors and two supervisors were involved in gathering the data. The data were analyzed using descriptive statistics and logistic regression and were entered into Epi Info and analyzed by using the SPSS software package version 20.

Results: This study revealed that the TB treatment success rate was 86.1% (169 [22.9%] cured and 467 [63.2%] completed). In addition, 22 (3%) of the study participants defaulted their treatment of which 19 (86.4%) withdrew during the intensive phase. The multiple logistic regression model revealed that the study year of treatment, sputum smear positivity at the second-month follow-up, history of treatment default, and subsequent hospitalization were significantly associated with the TB treatment outcome.

Conclusion: The TB treatment success rate in the study area was low compared to that estimated by World Health Organization to achieve by 2015. Therefore, Federal Ministry of Health and Regional and Zonal Health Office have to strengthen the interventions on minimizing anti-TB treatment default rate through well-organized documentation, follow-up on TB patients, and awareness-creation programs.

Background: Intestinal parasites' eggs, larvae, or cysts can be carried in public transport buses, and contribute to the increased incidence of diseases. This study aimed to detect biological forms of intestinal parasites in samples from public buses in the town of Diamantina, Minas Gerais, in order to know the local situation and propose interventions to improve public health.

Materials and methods: In November 2014, six samples were obtained in buses of the two stations by using Graham method, in duplicate, by affixing a 6×5 cm clear tape, six times on each collection site of the bus, in an area of ~30 cm². Then, each tape was positioned longitudinally on a slide microscope, and the identification of the biological forms of the parasites was performed with the aid of a 40× objective optical microscope.

Results: A total of 216 slides were analyzed, of which 86 (39.8%) were positive for at least one intestinal parasite. Cysts of Entamoeba coli were the most frequently found in this study (52.1%), followed by Endolimax nana cysts (30.7%), Iodamoeba butschlii (6.5%), helminth larvae (4.7%), Giardia lamblia cysts (3.6%), Hymenolepis nana eggs (1.2%), Enterobius vermicularis eggs (0.6%), and Entamoeba histolytica cysts (0.6%). Top right handrails and right stanchions had the highest occurrence of biological forms, with 18.3% and 14.8%, respectively.

Conclusion: The results indicated the need for better cleaning of the buses and better personal hygiene by users, since pathogenic and non-pathogenic intestinal parasites were found, suggesting fecal contamination of these sites, representing a risk to public health.

Chikungunya, dengue, and Zika viruses (CHIKV, family Togaviridae, genus Alphavirus; DENV and ZIKV, family Flaviviridae, genus Flavivirus) are arboviruses that cause human epidemics. Due to the lack of vaccines for many mosquito-borne diseases, there is a need for mosquito control. In the US and other regions, residual barrier insecticide sprays are applied to foliage where female mosquitoes rest and/or sugar feed between blood meals. Residual sprays are an important control method for anthropogenic day-active sylvan mosquitoes such as Aedes albopictus (vector of CHIKV, DENV, and ZIKV) that are difficult to control using ultralow-volume sprays applied only at dusk or dawn when these mosquitoes are not active. In this exploratory study, we analyzed the extent to which ingestion of a sublethal dose of the active ingredient bifenthrin affected vector competence (i.e., infection, dissemination, and transmission) of Ae. albopictus for DENV and ZIKV. Two incubation periods (IPs; 7 and 14 d) were tested at 28°C for insecticide-fed and sugar-fed mosquitoes. We show that mosquitoes that were fed bifenthrin (0.128 µg/mL) mixed with sucrose solution exhibited significantly lower DENV infection rates and body titers after a 14-d IP. During the 7-d IP, one mosquito (sugar group) transmitted ZIKV. During the 14-d IP, 100% of mosquitoes showed body and leg ZIKV infections, and one mosquito (sugar+bifenthrin group) transmitted ZIKV. This is a preliminary communication, and more studies will be required to further investigate these findings. We expect the findings of this small-scale study to spur larger-scale investigations of the impacts of insecticides on mechanisms regulating vector competence, and exposure to other active ingredients, and aid in development of new insecticides.