Tropical Diseases, Travel Medicine and Vaccines

Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of infectious diarrhea in children. There are no licensed vaccines against ETEC. This study aimed at characterizing Escherichia coli for ETEC enterotoxins and colonization factors from children < 5 years with acute diarrhea and had not taken antibiotics prior to seeking medical attention at the hospital. A total of 225 randomly selected archived E. coli strains originally isolated from 225 children with acute diarrhea were cultured. DNA was extracted and screened by multiplex polymerase chain reaction (PCR) for three ETEC toxins. All positives were then screened for 11 colonization factors by PCR. Out of 225 E. coli strains tested, 23 (10.2%) were ETEC. Heat-stable toxin (ST) gene was detected in 16 (69.6%). ETEC isolates with heat-stable toxin of human origin (STh) and heat-stable toxin of porcine origin (STp) distributed as 11 (68.8%) and 5 (31.2%) respectively. Heat-labile toxin gene (LT) was detected in 5 (21.7%) of the ETEC isolates. Both ST and LT toxin genes were detected in 2 (8.7%) of the ETEC isolates. CF genes were detected in 14 (60.9%) ETEC strains with a majority having CS6 6 (42.9%) gene followed by a combination of CFA/I + CS21 gene detected in 3 (21.4%). CS14, CS3, CS7 and a combination of CS5 + CS6, CS2 + CS3 genes were detected equally in 1 (7.1%) ETEC isolate each. CFA/I, CS4, CS5, CS2, CS17/19, CS1/PCFO71 and CS21 genes tested were not detected. We did not detect CF genes in 9 (39.1%) ETEC isolates. More CFs were associated with ETEC strains with ST genes. ETEC strains with ST genes were the most common and had the most associated CFs. A majority of ETEC strains had CS6 gene. In 9 (39.1%) of the evaluated ETEC isolates, we did not detect an identifiable CF.

An organism’s immune response to a vaccine is dependent on a number of factors, including the site of immunization. While muscle is the most common site for vaccine administration, other sites, including the salivary gland, are poised to confer stronger and broader immunoprotection. Studies exploring the salivary gland as an immunization site have involved protein antigens, as well as live pathogens and DNA vaccines. While intraductal instillation of protein antigens into the salivary gland may result in a relatively transient increase in antibody production, DNA or attenuated pathogen vaccination appear to confer a lasting widespread mucosal immune response that includes robust salivary and enteric IgA, as well as high levels of circulating IgG. Furthermore, vaginal and lung antibodies are also seen. For enteric pathogens, a common class of pathogen encountered by travelers, this type of immune response provides for a level of redundant protection against foreign microbes with mucosal targets. The strength of immune response conferred by salivary gland vaccination is generally stronger than that seen in response to the same vaccine at a comparison site. For example, where other routes fail, immunization of the salivary gland has been shown to confer protection in lethal challenge models of infectious pathogens. A host of vaccines currently under development suffer from immunogenicity challenges, adding to the widespread interest and search for novel routes and adjuvants. With its capability to facilitate a strong and broad immune response, the salivary gland warrants consideration as an immunization site, especially for vaccines with immunogenicity challenges, as well as vaccines that would benefit from combined systemic and mucosal immunity.

The arrival of COVID-19 impacted every aspect of life around the world. The virus, whose spread was facilitated overwhelmingly by people’s close contact at home and by travelling, devastated the tourism, hospitality, and transportation industry. Economic survival depended largely on demonstrating to authorities and potential travellers the strict adherence to infection control measures. Fortunately, long before the pandemic, the industry had already employed digital technology, artificial intelligence, and service robots, not to keep the world safe, but to either bridge staff shortages or save costs, reduce waiting times, streamline administration, complete unattractive, tedious, or physical tasks, or use technology as marketing gimmicks. With COVID-19, offering social distancing and touchless service was an easy step by extending quickly what was already there. The question arose: could travellers’ acceptance of technology and robots for infection control be useful in travel medicine? COVID-19 fostered the rapid and increased acceptance of touchless technology relating to all things travel. The public’s expectations regarding hygiene, health and safety, and risk of infection have changed and may stay with us long after the pandemic is ‘the new normal’, or a new one approaches. This insight, combined with the current experience with robots in health and medicine, is useful in exploring how robots could assist travel medicine practice. However, several aspects need to be considered in terms of type of robot, tasks required, and the public’s positive or negative attitudes towards robots to avoid known pitfalls. To meet the crucial infection control measures of social distancing and touch avoidance, the use of robots in travel medicine may not only be readily accepted but expected, and implications for management, practice, and research need to be considered.

Many health departments and private enterprises began offering SARS-CoV-2 testing to travelers at US airports in 2020. Persons with positive SARS-CoV-2 test results who have planned upcoming travel may be subject to US federal public health travel restrictions. We assessed availability of testing for SARS-CoV-2 at major US airports. We then describe the management of cases and close contacts at Denver International Airport’s testing site. We selected 100 US airports. Online surveys were conducted during November–December 2020 and assessed availability of testing for air travelers, flight crew, and airport employees. Respondents included health department (HD) staff or airport directors. We analyzed testing data and management practices for persons who tested positive and their close contacts at one airport (Denver International) from 12/21/2020 to 3/31/2021. Among the 100 selected airports, we received information on 77 airports; 38 (49%) had a testing site and several more planned to offer one (N = 7; 9%). Most sites began testing in the fall of 2020. The most frequently offered tests were RT-PCR or other NAAT tests (N = 28). Denver International Airport offered voluntary SARS-CoV-2 testing. Fifty-four people had positive results among 5724 tests conducted from 12/21/2020 to 3/31/2021 for a total positivity of < 1%. Of these, 15 were travelers with imminent flights. The Denver HD issued an order requiring the testing site to immediately report cases and notify airlines to cancel upcoming flight itineraries for infected travelers and their traveling close contacts, minimizing the use of federal travel restrictions. As of December 2020, nearly half of surveyed US airports had SARS-CoV-2 testing sites. Such large-scale adoption of airport testing for a communicable disease is unprecedented and presents new challenges for travelers, airlines, airports, and public health authorities. This assessment was completed before the US and other countries began enforcing entry testing requirements; testing at airports will likely increase as travel demand returns and test requirements for travel evolve. Lessons from Denver demonstrate how HDs can play a key role in engaging airport testing sites to ensure people who test positive for SARS-CoV-2 immediately before travel do not travel on commercial aircraft.

Hepatitis B and C virus, Opisthorchis viverrini and Clonorchis sinensis, are all individually known to put a person at increased risk for cholangiocarcinoma and hepatocellular carcinoma. This paper seeks to determine if there is any interaction between liver flukes and hepatitis virus infection that are known to put a person at an increased risk for cholangiocarcinoma and hepatocellular carcinoma collectively. This paper seeks to determine whether there is any publicly available articles in English that determine if having a hepatitis viral co-infection along with liver flukes would influence the risk of developing liver cancer. We followed PRISMA systematic review guidelines to conduct a literature review. Three manuscripts fit the search criteria. Two presented evidence in support of a synergistic relationship between liver fluke and viral hepatitis infection while the other found no relationship. One manuscript determined that the interaction between hepatitis B and C. sinensis did not have any significant risk of liver cancer. Studies found that HBV affected progression of co-infection to liver cancer but may have its own disease state worsened by presence of liver flukes. Only one paper was found that presented data on HCV, therefore no conclusion can be drawn due to the lack of evidence discovered. Of the studies, the conclusions and strength of the data were mixed. However, the stronger studies suggested a synergistic relationship between liver flukes and HBV to increase the risk of progressing to liver cancer.

Efforts in search of lasting malaria vaccine have led to the development of transgenic rodent malaria parasites. As a result, wild type Plasmodium berghei ANKA (WTPbA) has recently been transformed to express mouse interferon gamma (mIFN-γ). The immunomodulatory effect of this transgenic parasite on WTPbA infection has been demonstrated. However, the protective immune responses after repeated immunization with soluble lysate of this parasite has not been investigated. Soluble lysate of transgenic PbA (TPbA) was prepared and concentration of IFN-γ in lysate determined by ELISA. Four groups of 20 BALB/c mice each (two treatment groups and two control groups) were setup. Treatment Groups 1 and 2 were primed (at day 0) with lysate of TPbA containing 75 pg/ml IFN-γ and live TPbA parasites respectively. Infection in Group 2 mice was cured with Coartem™ at 450 mg/kg for 3 days. At day 14 post-priming, both groups were boosted twice at day 14 and day 28 with lysate of TPbA containing 75 pg/ml IFN-γ and 35 pg/ml IFN-γ respectively. Blood and spleen samples were collected at day 0, day 14, day 21 and day 28 for preparation of serum and cell cultures respectively. Serum IgG and cytokines (TNF-α and IFN-γ) levels in culture supernatant were measred by ELISA.Survivorship and parasitemia were daily monitored for 21 days. Data were statistically analyzed using ANOVA student’s t test. A p value of <0.05 was considered significant. At day 28 post-priming, IFN-γ production in Group 1 was tenfold higher than in RBC control group (p = 0.070) There was significant difference in IFN-γ production among the groups at day 28 (p < 0.0001). TNF-α production in Group 1 mice increased fourfold in Group 2 mice from day 14 to day 28 post-immunization (p = 0.0005). There was no significant effect on serum IgG production. Mice in treatment groups survived 5 to 4 days longer compared to non-immunized group. The study has demonstrated that, repeated immunization with soluble lysate of TPbA induces Th 1 response leading to increased IFN-γ and TNF-γ production.

A tetravalent DNA vaccine for Dengue virus is under development but has not yet achieved optimal immunogenicity. Salivary glands vaccination has been reported efficacious in rodents and dogs. We report on a pilot study testing the salivary gland as a platform for a Dengue DNA vaccine in a non-human primate model. Four cynomolgus macaques were used in this study. Each macaque was pre-medicated with atropine and sedated with ketamine. Stensen’s duct papilla was cannulated with a P10 polyethylene tube, linked to a 500ul syringe. On the first two infusions, all macaques were infused with 300ul of TVDV mixed with 2 mg of zinc. For the 3rd infusion, to increase transfection into salivary tissue, two animals received 100uL TVDV mixed with 400uL polyethylenimine 1μg/ml (PEI) and the other two animals received 500uL TVDV with zinc. Antibody titers were assessed 4 weeks following the second and third infusion. SGRI through Stensen’s duct is a well-tolerated, simple and easy to reproduce procedure. TVDV infused into macaques salivary glands elicited a significantly weaker antibody response than with different delivery methods.

Du lịch quốc tế là một trong những yếu tố ảnh hưởng lớn đến sự lây lan của dịch COVID-19; do đó, kiến thức đầy đủ, thái độ tốt và các thực hành phòng ngừa hiệu quả đối với COVID-19 cho những người du lịch quốc tế là vô cùng quan trọng để kiểm soát đại dịch thành công. Một nghiên cứu cắt ngang dựa trên bảng hỏi đã được thực hiện nhằm xác định kiến thức, thái độ và thực hành (KAP) của những người du lịch quốc tế (cả người Thái và không phải người Thái) và những người nước ngoài tại Thái Lan. Dữ liệu đã được thu thập tại Phòng khám Du lịch Thái, Bangkok, Thái Lan và qua các nền tảng trực tuyến từ tháng 5 đến tháng 10 năm 2020. Các bài kiểm tra T độc lập, kiểm tra Chi-bình phương và phân tích hồi quy nhiều biến (MRA) đã được áp dụng để xác định các yếu tố ảnh hưởng đến KAP. Trong số 399 người tham gia, 46.6% là nam, 72.1% có bằng Đại học hoặc cao hơn, và độ tuổi trung bình là 35.6 ± 9.6 năm. Do các hạn chế đi lại không lường trước và phong tỏa, 77.9% người tham gia là người Thái và mục đích chính của chuyến đi là kinh doanh/công việc. Tỷ lệ hủy/hoãn chuyến đi được báo cáo là 73.9%. Trong khi kiến thức đầy đủ (≥ 60% câu trả lời đúng) được báo cáo ở 77.9% người tham gia, tỷ lệ câu trả lời đúng thấp được tìm thấy trong các câu hỏi liên quan đến sự truyền nhiễm bệnh. Những người du lịch báo cáo có thái độ trung lập và mối quan tâm tổng thể ở mức trung bình về tình hình COVID-19. Thực hành phòng ngừa đầy đủ được xác định bởi điểm thực hành trung bình 3.54 ± 0.38 (0 = không bao giờ và 4 = luôn luôn). Kết quả MRA cho thấy các yếu tố ảnh hưởng đến các thực hành tốt là những người du lịch đã: i) đăng ký từ bên ngoài bệnh viện (nền tảng trực tuyến); ii) nhận tư vấn trước chuyến đi tại bệnh viện; iii) là nữ; iv) tham gia trước khi tuyên bố kết thúc đợt bùng phát; v) từ 40–49 tuổi, và vi) thăm bạn bè và người thân. Phần lớn những người tham gia du lịch trong nghiên cứu này có kiến thức đầy đủ, thái độ trung lập và các thực hành phòng ngừa đầy đủ đối với COVID-19. Các yếu tố ảnh hưởng đến các thực hành tốt bao gồm tư vấn trước chuyến đi, giới tính, độ tuổi và giai đoạn trong thời gian bùng phát. Để kiểm soát tốt hơn tình hình đại dịch COVID-19, cần thúc đẩy việc tư vấn và khuyến cáo trước khi đi để cải thiện kiến thức, đặc biệt là về sự lây truyền của bệnh, tăng cường nhận thức và nhấn mạnh các biện pháp phòng ngừa phù hợp đối với COVID-19 trong số các du khách quốc tế. Hơn nữa, các thực hành phòng ngừa cần được củng cố mọi lúc, bất kể tình hình bùng phát.

Increasing numbers of older individuals opt to spend extended time abroad each year for lifestyle, health, and financial reasons. This practice is known as international retirement migration, and it is particularly popular among retirees in Global North countries such as Canada. Despite the popularity of international retirement migration, very little is known about how and why health care is accessed while abroad, nor the opportunities and challenges posed for destination hospitals. In this article we focus on addressing the latter knowledge gap. This qualitative case study is focused on the only hospital in Yuma, Arizona – a popular destination for Canadian retirement migrants in the United States. We conducted focus groups with workers at this hospital to explore their experiences of treating this transnational patient group. Twenty-seven people participated in three, 90-min focus groups: twelve nurses, six physicians, and nine administrators. Thematic analysis of the focus group transcripts was conducted using a triangulated approach. Participants identified three care environments: practice, transnational, and community. Each environment presents specific opportunities and challenges pertaining to treating Canadian retirement migrants. Important opportunities include the creation of a strong and diverse seasonal workforce in the hospital, new transnational paths of communication and information sharing for physicians and health administrators, and informal care networks that support formal health care services within and beyond the hospital. These opportunities are balanced out by billing, practical, administrative, and lifestyle-related challenges which add complexity to treating this group of transnational patients. Canadians represent a significant group of patients treated in Yuma, Arizona. This is contrary to long-standing, existing research that depicts older Canadians as being reluctant to access care while in the United States. Significant overlaps exist between the opportunities and challenges in the practice, transnational and community environments. More research is needed to better understand if these findings are similar to other destinations popular with Canadian international retirement migrants or if they are unique to Yuma, Arizona.

Onchocerciasis is among the Neglected Tropical Diseases (NTDs) responsible for dermatological, ophthalmological, and neurological manifestations. With the ongoing burden of onchocerciasis clinical manifestations, morbidity management, and disability prevention services are required to alleviate the suffering of the affected populations. Unfortunately, despite the ongoing transmission of onchocerciasis, morbidity management, and disability prevention services are limited in Tanzania. Therefore, this article highlights the concept of onchocerciasis morbidity management and disability prevention, along with the significance of its adoption in the healthcare system in Tanzania. We further provide recommendations on where and how to start.