Imported diseases: an assessment of trends

Increasing travel, migration and other forms of international exchange have given a new importance to imported diseases in Canada. This is reflected in the maintenance of an immigration medical screening program, the development of specialized clinics in major cities, increasing interest in tropical medicine and international health, and the designation of a national reference centre for parasitology.The introduction of a point system for immigration selection in 1967 gave rise to a burgeoning influx of people from developing countries that may have plateaued only within the past year. While tuberculosis is probably the single most important health problem in immigration, parasitic infections are of increasing concern. The popularity of overseas travel among Canadians is now also a major factor in the introduction of exotic diseases into Canada. Importation of disease by international trade is far less common than by travel and immigration.On a community health scale a system of monitoring trends of immigration to Canada and travel of Canadians to and from countries with a known risk would likely provide the best indicator of trends in disease importation. Thus, there was an increase of almost threefold (11.6% to 31.1%) between 1965 and 1975 in the proportion of immigration to Canada from countries with a malaria risk and a 2.78-fold increase between 1967 and 1974 in the overall amount of Canadian travel to such countries from which statistics were available.     

Cost benefit analysis of sexually transmitted diseases.

Suggested measures to prevent transmission and sequelae of sexually transmitted diseases are almost universally agreed. But the important question to be answered is whether the interventions are worth the resources spent. To facilitate the decision making on resource allocation, the best possible information should be available concerning the relationships between health intervention programs and changes in the health status. Cost benefit analysis is the main approach used to assess the efficiency of any intervention. If the economic benefits of the program are greater than the costs, the program should be seriously considered. Although information about the costs of management of STDs is scarce in developing countries because of the complicated behavioral, social and economic issues involved, it is widely held that making treatment available for curable sexually transmitted diseases represents one of the most cost-effective ways to improve the health in the world.     

Lesbian health care. What a primary care physician needs to know.

Many primary care physicians take care of lesbians and women sexually active with women without being aware of their patients'' sexual orientation. These women have unique medical and psychosocial needs that each physician must consider. Lesbian identity or being sexually active exclusively with women influences care in areas such as sexually transmitted diseases, risk of human immunodeficiency virus infection, counseling, cancer risk, screening, parenting, depression, alcohol use, and violence. We review an approach to taking a history with all women that facilitates open, comfortable communication with lesbians. We also review specific medical and psychosocial areas of primary care in which caring for lesbians is different from caring for other women. Further research is needed on lesbian health issues to provide appropriate guidelines to clinicians.     

Teaching and training in geriatric medicine in the European Union

In 1993 about 20% of the population in the 15 'old' member countries of the European Union (EU) was over 60 years of age and this percentage will increase to more than 25% in 2020. These developments play a key role for the investments in education and training to meet societies needs for health care services. In 2002 about 25% of the medical students in the 'old' EU did not receive any education in geriatric medicine. A question is who will provide the services for older people in related areas, like social care, community care, acute care in the hospitals, long-term care, permanent care and care for psychiatric patients? Geriatric medicine has been recognized as an independent specialty in 8 of the 15 member countries of the 'old' EU. In all EU member states the governments are autonomous regarding all aspects of health care services, including the recognition of specialties and specialist training programmes. A two years training in internal medicine has been recommended in the EU, followed by another four years of training in geriatric medicine. The specialist training has a hospital oriented character, however, it includes also community care and other institutionalised care like nursing homes. The curriculum should contain: biological, social, psychological and medical aspects of common diseases and disturbances in older people. A problem in many EU countries is the shortage of well trained researchers and leading persons for academic positions for geriatric medicine. In a number of countries chairs at the universities remain vacant for long periods of time or even disappear. Good services in the health care for older people need a high quality curriculum and training programme.     

Adolescent health care in a large multispecialty prepaid group practice. Who provides it and how well are they doing?

Adolescents are at risk for pregnancy, sexually transmitted diseases, suicide, homicide, accidents, and substance abuse. Adolescent medicine involves an overlap of many skills needed to provide routine medical care, as well as care for those conditions that require psychosocial assessment. We report the results of a mail survey covering care of this age group by practitioners of pediatrics, internal medicine, obstetrics and gynecology, family practice, and adolescent medicine in a large, multispecialty, prepaid group practice. The mail survey covered 10 areas of adolescent care. Adolescent medicine physicians expressed the highest level of perceived knowledge and competence in these areas, with family practitioners ranked second. More than 50% of internists and pediatricians felt only fair to poor competence for a variety of adolescent conditions, whereas a third of internists and pediatricians reported that they liked to care for adolescents. Physicians in all 4 of the primary care specialties reported a need for a teen health center for both consultation and education. These results are similar to those reported for pediatricians and primary care physicians in private practice and for residents in internal medicine.     

Why do we need quality-assured diagnostic tests for sexually transmitted infections?

The bacterial sexually transmitted infections (STIs) syphilis, gonorrhoea and chlamydia can all be cured with a single dose of antibiotic. Unfortunately, however, these infections often remain undiagnosed as many infected individuals have few if any symptoms. Diagnostic tests with high sensitivity and specificity are available for all three infections but, owing to their expense and the lack of laboratory capacity, most people in developing countries do not have access to these tests. There is a great need for simple, cheap diagnostic tests for STIs that can be performed at the point of care, enabling treatment to be given immediately. It is hoped that recent advances in our understanding of the pathogenesis of these infections, and the availability of the complete genome sequences for each causative organism, will lead to the development of improved point-of-care tests that will reduce the burden of these diseases in developing countries.     

Demographic shifts and medical training

The rapid aging of populations in developing countries as compared to those in the developed world has implications for medical training in these places. Moreover, the growing globalization of employment for many health professionals means that demographic shifts have implications for the training of health professionals worldwide such that curriculums in developing countries may not meet the needs of those who practice in industrialized countries. Chronic and degenerative diseases as well as problems of multiple pathology are likely to increase with an aging population. Consequently, multiple pathology makes current medical training so likely to lead to inappropriate and poor quality of care. In addition, increasing subspecialization in medicine provides doctors who are unable to deal with the complexity of multiple pathology. Undergraduate medical education reforms are also forcing specific training in geriatric medicine out of the curriculums.     

The Organization of schistosomiasis control programmes

A major constraint to the control of communicable diseases in developing countries is the lack of adequate institutionalization of public health activities. The usual political perception is that the public will benefit more from economic and social development than from public health interventions. Planners and politicians generally hold that investment in rural electrification, roads and education will bring more long-term benefit than equivalent investments in public health. Sadly therefore, public health interventions have usually been designed and implemented as short-term, high-return activities in an atmosphere of unrealistic optimism. This criticism can be applied to most tropical diseases, but the potential of new weapons against many of the most widespread parasitic diseases places some urgency on an analysis of the most effective way to implement these interventions. In an attempt to identify and begin to resolve some of these issues, The World Bank, WHO and McConnell Clark Foundation sponsored a workshop on the Organization and Management of Schistosomiasis and other Tropical Disease Control Programmes. The meeting addressed general issues of the organization of public health services, but focused on schistosomiasis where the development of effective, single oral dose chemotherapy (using oxamniquine or praziquantel) is seen as a realistic intervention for large-scale control throughout the 74 endemic countries. In this article, Bernhard Liese reviews the institutional questions, drawing examples from the often cited control programmes in Brazil, Ghana, Egypt, Morocco, Sudan and the Philippines.     

The effect of combat exposure on sexually transmitted diseases

Traumatic exposures can affect beliefs and behaviors related to the spread of sexually transmitted diseases (STDs), a persistent public health problem. I leverage a natural experiment created by variation in US military deployment location assignments to estimate how combat exposure changes a surviving deployed male veteran’s probability of acquiring a sexually transmitted disease. I analyze longitudinal data from 1994 to 2008 on 485 deployed veterans with information theoretic methods to reduce the sensitivity of estimates to small samples, an infrequently observed outcome, and highly correlated covariates. For veterans assigned to a combat zone, I estimate combat exposure results in a 5.4 percentage point increase in the probability of acquiring an STD. Additional estimations provide evidence suggesting risky behaviors involving substance use or multiple sexual partners may serve as pathways from combat exposure to STDs. My results are relevant to discussions regarding STD screening and care needs for trauma exposed individuals.     

Past Japanese successes show the way to accomplish future goals

Many parasitic diseases have been eradicated in industrialized countries and well-proven tools and techniques exist to control them. However, the same diseases still cause incalculable ill health and suffering in the developing world. The difficulty remains how best to apply existing solutions where they are most needed. Within a period of 25 years following World War II, Japan eliminated many parasitic diseases and raised national health and living standards to world-leading levels. Gradually, the predominantly community-driven and intersectoral collaborative partnership systems (i.e. private sector, public sector, general public, etc.) and practices that worked in Japan are being extended to Asia and now Africa. These are backed by the provision of substantial human and financial resources from a nation whose population retains the reputation as being the healthiest and longest living in the world.     

Do Antenatal Parasite Infections Devalue Childhood Vaccination?

On a global basis, both potent vaccine efficacy and high vaccine coverage are necessary to control and eliminate vaccine-preventable diseases. Emerging evidence from animal and human studies suggest that neglected tropical diseases (NTDs) significantly impair response to standard childhood immunizations. A review of efficacy and effectiveness studies of vaccination among individuals with chronic parasitic infections was conducted, using PUBMED database searches and analysis of data from the authors'' published and unpublished studies. Both animal models and human studies suggest that chronic trematode, nematode, and protozoan infections can result in decreased vaccine efficacy. Among pregnant women, who in developing countries are often infected with multiple parasites, soluble parasite antigens have been shown to cross the placenta and prime or tolerize fetal immune responses. As a result, antenatal infections can have a significant impact on later vaccine responses. Acquired childhood parasitic infections, most commonly malaria, can also affect subsequent immune response to vaccination. Additional data suggest that antiparasite therapy can improve the effectiveness of several human vaccines. Emerging evidence demonstrates that both antenatal and childhood parasitic infections alter levels of protective immune response to routine vaccinations. Successful antiparasite treatment may prevent immunomodulation caused by parasitic antigens during pregnancy and early childhood and may improve vaccine efficacy. Future research should highlight the varied effects that different parasites (alone and in combination) can have on human vaccine-related immunity. To optimize vaccine effectiveness in developing countries, better control of chronic NTDs may prove imperative.     

Neglected tropical diseases in Central America and Panama: Review of their prevalence,populations at risk and impact on regional development

A review of the literature since 2009 reveals a staggering health and economic burden resulting from neglected tropical diseases in Panama and the six countries of Central America (referred to collectively here as ‘Central America’). Particularly at risk are the 10.2 million people in the region who live on less than $2 per day, mostly in Guatemala, Honduras, Nicaragua and El Salvador. Indigenous populations are especially vulnerable to neglected tropical diseases. Currently, more than 8 million Central American children require mass drug treatments annually (or more frequently) for their intestinal helminth infections, while vector-borne diseases are widespread. Among the vector-borne parasitic infections, almost 40% of the population is at risk for malaria (mostly Plasmodium vivax infection), more than 800,000 people live with Chagas disease, and up to 39,000 people have cutaneous leishmaniasis. In contrast, an important recent success story is the elimination of onchocerciasis from Central America. Dengue is the leading arbovirus infection with 4–5 million people affected annually and hantavirus is an important rodent-borne viral neglected tropical disease. The leading bacterial neglected tropical diseases include leptospirosis and trachoma, for which there are no disease burden estimates. Overall there is an extreme dearth of epidemiological data on neglected tropical diseases based on active surveillance as well as estimates of their economic impact. Limited information to date, however, suggests that neglected tropical diseases are a major hindrance to the region’s economic development, in both the most impoverished Central American countries listed above, as well as for Panama and Costa Rica where a substantial (but largely hidden) minority of people live in extreme poverty.     

Verbal Intercourse and Sexual Communication: Impediments to STD Prevention

This article explores the problems of risky sexual behavior by examining the ways people verbally negotiate sexual interaction regarding sexually transmitted diseases. Based on in-depth interviews with 124 adults (ages 21–63) who are infected with genital herpes, the article shows that knowledge about sexually transmitted diseases is not necessarily related to the action needed for their prevention. People are more afraid of being rejected by a partner than they are of contracting an STD (except, of course, AIDS). By examining difficulties people have with sexual health discourse and showing how these difficulties are related to both the problem of communicating politeness and the problem of representing the self and the sexual other, this article demonstrates that STD prevention programs overlook a very important emotional and communicative issue: the lack of a culturally sanctioned language with which to discuss sexual health with partners, [genital herpes, STD prevention, STD communication, sexually transmitted diseases, STD risk]     

RNAi pathways in parasitic protists and worms

Tropical diseases caused by parasitic worms and protists are of major public health concern affecting millions of people worldwide. New therapeutic and diagnostic tools would be of great help in dealing with the public health and economic impact of these diseases. RNA interference (RNAi) pathways utilize small non-coding RNAs to regulate gene expression in a sequence-specific manner. In recent years, a wealth of data about the mechanisms and biological functions of RNAi pathways in distinct groups of eukaryotes has been described. Often, RNAi pathways have unique features that are restricted to groups of eukaryotes. The focus of this review will be on RNAi pathways in specific groups of parasitic eukaryotes that include Trypanosoma cruzi, Plasmodium and Schistosoma mansoni. These parasites are the causative agents of Chagas disease, Malaria, and Schistosomiasis, respectively, all of which are tropical diseases that would greatly benefit from the development of new diagnostic and therapeutic tools. In this context, we will describe specific features of RNAi pathways in each of these parasitic eukaryotic groups and discuss how they could be exploited for the treatment of tropical diseases.     

Changing patterns of parasitic disease: old enemies and new invaders--the battle wages on

• 1.A. The classic parasitic diseases—malaria, schistosomiasis, the filariases, and many other familiar “old enemies”—continue to be the major parasitic causes of morbidity and morality and the continuing objects of our research and control efforts. Although all have been receptive to control interventions under certain circumstances, most of these infections continue to be transmitted without apparent restrictions in the rural, developing regions where nearly one-half of all the world's people live. New technologie achievements will improve the chances for treatment and control of these infections, but more important, may be improved administrative capacity and the commitment of political will and economic resources toward these goals.
• 2.B. The emergence of resistance to drugs and chemical control agents as a result of selection of resistant strains in the face of exposure to the chemical is a growing phenomenon among parasites with very serious public health implications. Strains of Plasmodium falciparum resistant to most drugs formerly effective for prophylaxis and treatment have appeared in Africa, Asia and parts of South and Central America at a faster pace than new compounds can be made available. Similar problems have been reported with gastrointestinal nematodes of livestock animals and many insect vectors.
• 3.C. Cryptosporidiosis emerged dramatically as a human disease when it appeared as one of the many opportunistic infections suffered by patients with AIDS. Increased clinical awareness and improved diagnostic procedures have now implicated Cryptosporidium as an important worldwide cause of diarrheal illness in persons with normal immunologic function. Zoonotic and various forms of person-to-person transmission are now recognized as important modes of spread for this protozoan.
• 4.D. Development and widespread use of specific serodiagnostic tests for human toxocariasis has revealed that zoonotic transmission of the common dog and cat ascarids is widespread in populations in industrialized societies. Serologic studies suggest that human Toxocara infection is even more common in tropical, developing areas but the health impact of this has not yet been measured. New nematode agents of larva migrans have been identified recently. One of them, the racoon ascarid, Baylisascaris procyonis, may increase in importance as its host extends its range as a commensal resident.
• 5.E. In developed countries where social and environmental conditions limit opportunities for transmission of most protozoal and helminthic disease agents, parasitic diseases are seen often as imported infections in returning tourists or immigrants who became infected in foreign endemic areas. One of these, imported malaria, has been exacerbated in the past decade by the resurgence of malaria transmission in Asia, the resettlement, in many countries, of refugees from Southeast Asia, and the spread of chloroquine-resistant P. falciparum in Africa.
• 6.F. Other special problems of parasitic diseases in developed countries include the increase in opportunistic parasitic pathogens (Pneumocystis, Toxoplasma, Strongyloides and others) in patients with AIDS and iatrogenically-caused immunodepression and the occurrence of infections resulting from changing dietary preferences and “fads”, e.g. diphyllobothriasis from “Shushi” and “Sashimi” (Japan, United States and Canada) and gnathostomiasis from imported fish (Japan).

     

A research agenda for helminth diseases of humans: health research and capacity building in disease-endemic countries for helminthiases control

Capacity building in health research generally, and helminthiasis research particularly, is pivotal to the implementation of the research and development agenda for the control and elimination of human helminthiases that has been proposed thematically in the preceding reviews of this collection. Since helminth infections affect human populations particularly in marginalised and low-income regions of the world, they belong to the group of poverty-related infectious diseases, and their alleviation through research, policy, and practice is a sine qua non condition for the achievement of the United Nations Millennium Development Goals. Current efforts supporting research capacity building specifically for the control of helminthiases have been devised and funded, almost in their entirety, by international donor agencies, major funding bodies, and academic institutions from the developed world, contributing to the creation of (not always equitable) North-South "partnerships". There is an urgent need to shift this paradigm in disease-endemic countries (DECs) by refocusing political will, and harnessing unshakeable commitment by the countries' governments, towards health research and capacity building policies to ensure long-term investment in combating and sustaining the control and eventual elimination of infectious diseases of poverty. The Disease Reference Group on Helminth Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. This paper discusses the challenges confronting capacity building for parasitic disease research in DECs, describes current capacity building strategies with particular reference to neglected tropical diseases and human helminthiases, and outlines recommendations to redress the balance of alliances and partnerships for health research between the developed countries of the "North" and the developing countries of the "South". We argue that investing in South-South collaborative research policies and capacity is as important as their North-South counterparts and is essential for scaled-up and improved control of helminthic diseases and ultimately for regional elimination.     

Essential diagnostics--the role of the Department of Biomedical Research of the Royal Tropical Institute in the 21st century

In the light of emerging and overlooked infectious diseases and widespread drug resistance, diagnostics have become increasingly important in supporting surveillance, disease control and outbreak management programs. In many low-income countries the diagnostic service has been a neglected part of health care, often lacking quantity and quality or even non-existing at all. High-income countries have exploited few of their advanced technical abilities for the much-needed development of low-cost, rapid diagnostic tests to improve the accuracy of diagnosis and accelerate the start of appropriate treatment. As is now also recognized by World Health Organization, investment in the development of affordable diagnostic tools is urgently needed to further our ability to control a variety of diseases that form a major threat to humanity. The Royal Tropical Institute's Department of Biomedical Research aims to contribute to the health of people living in the tropics. To this end, its multidisciplinary group of experts focuses on the diagnosis of diseases that are major health problems in low-income countries. In partnership we develop, improve and evaluate simple and cheap diagnostic tests, and perform epidemiological studies. Moreover, we advice and support others--especially those in developing countries--in their efforts to diagnose infectious diseases.     

A syndromic approach to common parasitic diseases

Standard textbooks discuss parasitic disease according to specific organisms. In contrast, patients with parasitic infections present to physicians with a variety of clinical manifestations that may involve any of several organ systems and that often mimic nonparasitic diseases. A syndromic approach to the clinical situation may help the physician in considering the most important parasitic agents. Many parasitic infections can be acquired in temperate climates. While often considered tropical or exotic, other parasitic diseases are now seen more frequently in developed countries because of immigration and increased world travel. In this review the clinical syndromes associated with common parasitic diseases in North America are discussed, with an emphasis on risk factors and diagnosis of specific infections.     

Arthropod-borne diseases: vector control in the genomics era

Diseases that are transmitted by arthropods cause severe morbidity and mortality throughout the world. The burden of many of these diseases is borne largely by developing countries. Advances in vector genomics offer new promise for the control of arthropod vectors of disease. Radical changes in vector-biology research are required if scientists are to exploit genomic data and implement changes in public health.