Tropical Infections in the Context of Kidney Transplantation in Latin America

Reports on tropical infections among kidney transplant (KT) recipients have increased in recent years, mainly because of the growing number of KT programs located in tropical and subtropical areas, and greater mobility or migration between different areas of the world. Endemic in emerging and developing regions, like most countries in Latin America, tropical infections are an important cause of morbidity and mortality in this population. Tropical infections in KT recipients may exhibit different pathways for acquisition compared with those in nonrecipients, such as transmission through a graft and reactivation of a latent infection triggered by immunosuppression. Clinical presentation may differ compared with that in immunocompetent patients, and there are also particularities in diagnostic aspects, treatment, and prognosis. KT patients must be screened for latent infections and immunized properly. Last, drug-drug interactions between immunosuppressive agents and drugs used to treat tropical infections are an additional challenge in KT patients. In this review, we summarize the management of tropical infections in KT patients.

[Jungle yellow fever with positive serology for leptospira in a young peruvian male]

Yellow fever (YF) and leptospirosis are under-diagnosed endemic zoonoses of the tropical regions of Africa and South America. Both may be clinically indistinguishable and present as an acute icterohemorrhagic febrile syndrome. We report the case of a 20-year-old male from the department of Amazonas who presented with nine days of disease characterized by multiorgan failure (neurological, renal, hepatic, respiratory, and hematological involvement). He received antibiotic treatment, as well as, transfusion, dialysis, hemodynamic, and ventilatory support. Despite the severity of the clinical condition, he evolved favorably. YF was confirmed by Rt-PCR and positive serology was obtained for leptospira by ELISA and microagglutination. However, from a laboratory point of view, real co-infection by yellow fever and leptospira could not be demonstrated. This case of severe YF with non-fatal outcome emphasizes the importance of adequate syndromic diagnosis, and early and aggressive supportive treatment that can save a patient's life.

Infectious Disease: Mosquito-Borne Viral Illnesses

Due to rapid globalization and ease of travel, mosquito-borne viral infections are now a concern for family physicians throughout the United States. Zika virus infection is one such concern. It is spread via mosquito bites or by sexual contact with an infected individual. Most patients are asymptomatic, and when symptoms occur, they are mild and nonspecific. The main concern is the potential of the infection to cause fetal anomalies. Dengue is another mosquito-borne viral infection. Symptoms of initial infection are mild, and may include arthralgias. Subsequent infection with a different serotype can cause life-threatening hemorrhagic fever or shock. Chikungunya virus infection is widespread in the Americas and symptoms are similar to those of dengue. However, it can cause a postviral chronic inflammatory rheumatism in up to half of patients. Yellow fever occurs mostly in sub-Saharan Africa and can cause hepatic failure. Encephalitis viruses, most commonly West Nile in the United States and others such as Japanese encephalitis virus, can cause neuroinvasive disease, most often in older adults. Vaccines are available for yellow fever and Japanese encephalitis viruses but the keys to prevention are insect avoidance, mosquito eradication, and use of mosquito repellants.

Unexpected healers: Chinese medicine in the age of global migration (Lima and California, 1850-1930)

The massive waves of Chinese migrants arriving in California and Lima in the second half of the nineteenth century played a crucial role in expanding Chinese medicine in both settings. From the late 1860s on, herbalists expanded their healing system beyond their ethnic community, transforming Chinese medicine into one of the healing practices most widely adopted by the local population. This article uses a comparative approach to examine the diverging trajectories of Chinese healers in Peru and the USA, as well as the social and political factors that determined how this foreign medical knowledge adapted to its new environments.

A humanized monoclonal antibody neutralizes yellow fever virus strain 17D-204 in vitro but does not protect a mouse model from disease

The yellow fever virus (YFV) vaccine 17D-204 is considered safe and effective, yet rare severe adverse events (SAEs), some resulting in death, have been documented following vaccination. Individuals exhibiting post-vaccinal SAEs are ideal candidates for antiviral monoclonal antibody (MAb) therapy; the time until appearance of clinical signs post-exposure is usually short and patients are quickly hospitalized. We previously developed a murine-human chimeric monoclonal antibody (cMAb), 2C9-cIgG, reactive with both virulent YFV and 17D-204, and demonstrated its ability to prevent and treat YF disease in both AG129 mouse and hamster models of infection. To counteract possible selection of 17D-204 variants that escape neutralization by treatment with a single MAb (2C9-cIgG), we developed a second cMAb, 864-cIgG, for use in combination with 2C9-cIgG in post-vaccinal therapy. MAb 864-cIgG recognizes/neutralizes only YFV 17D-204 vaccine substrain and binds to domain III (DIII) of the viral envelope protein, which is different from the YFV type-specific binding site of 2C9-cIgG in DII. Although it neutralized 17D-204 in vitro, administration of 864-cIgG had no protective capacity in the interferon receptor-deficient AG129 mouse model of 17D-204 infection. The data presented here show that although DIII-specific 864-cIgG neutralizes virus infectivity in vitro, it does not have the ability to abrogate disease in vivo. Therefore, combination of 864-cIgG with 2C9-cIgG for treatment of YF vaccination SAEs does not appear to provide an improvement on 2C9-cIgG therapy alone.

Animal models of yellow fever and their application in clinical research

Yellow fever virus (YFV) is an arbovirus that causes significant human morbidity and mortality. This virus has been studied intensively over the past century, although there are still no treatment options for those who become infected. Periodic and unpredictable yellow fever (YF) outbreaks in Africa and South America continue to occur and underscore the ongoing need to further understand this viral disease and to develop additional countermeasures to prevent or treat cases of illness. The use of animal models of YF is critical to accomplishing this goal. There are several animal models of YF that replicate various aspects of clinical disease and have provided insight into pathogenic mechanisms of the virus. These typically include mice, hamsters and non-human primates (NHP). The utilities and shortcomings of the available animal models of YF are discussed. Information on recent discoveries that have been made in the field of YFV research is also included as well as important future directions in further ameliorating the morbidity and mortality that occur as a result of YFV infection. It is anticipated that these model systems will help facilitate further improvements in the understanding of this virus and in furthering countermeasures to prevent or treat infections.

Yellow fever vaccine: recommendations of the Advisory Committee on Immunization Practices (ACIP)

This report updates CDC's recommendations for using yellow fever (YF) vaccine (CDC. Yellow fever vaccine: recommendations of the Advisory Committee on Immunizations Practices: MMWR 2002;51[No. RR-17]). Since the previous YF vaccine recommendations were published in 2002, new or additional information has become available on the epidemiology of YF, safety profile of the vaccine, and health regulations related to the vaccine. This report summarizes the current epidemiology of YF, describes immunogenicity and safety data for the YF vaccine, and provides recommendations for the use of YF vaccine among travelers and laboratory workers. YF is a vectorborne disease resulting from the transmission of yellow fever virus (YFV) to a human from the bite of an infected mosquito. It is endemic to sub-Saharan Africa and tropical South America and is estimated to cause 200,000 cases of clinical disease and 30,000 deaths annually. Infection in humans is capable of producing hemorrhagic fever and is fatal in 20%-50% of persons with severe disease. Because no treatment exists for YF disease, prevention is critical to lower disease risk and mortality. A traveler's risk for acquiring YFV is determined by multiple factors, including immunization status, location of travel, season, duration of exposure, occupational and recreational activities while traveling, and local rate of virus transmission at the time of travel. All travelers to countries in which YF is endemic should be advised of the risks for contracting the disease and available methods to prevent it, including use of personal protective measures and receipt of vaccine. Administration of YF vaccine is recommended for persons aged >or=9 months who are traveling to or living in areas of South America and Africa in which a risk exists for YFV transmission. Because serious adverse events can occur following YF vaccine administration, health-care providers should vaccinate only persons who are at risk for exposure to YFV or who require proof of vaccination for country entry. To minimize the risk for serious adverse events, health-care providers should observe the contraindications, consider the precautions to vaccination before administering vaccine, and issue a medical waiver if indicated.

Yellow fever control in Cameroon: where are we now and where are we going?

BACKGROUND

Cameroon is one of 12 African countries that bear most of the global burden of yellow fever. In 2002 the country developed a five-year strategic plan for yellow fever control, which included strategies for prevention as well as rapid detection and response to outbreaks when they occur. We have used data collected by the national Expanded Programme on Immunisation to assess the progress made and challenges faced during the first four years of implementing the plan.

METHODS

In January 2003, case-based surveillance of suspected yellow fever cases was instituted in the whole country. A year later, yellow fever immunisation at nine months of age (the same age as routine measles immunisation) was introduced. Supplementary immunisation activities (SIAs), both preventive and in response to outbreaks, also formed an integral part of the yellow fever control plan. Each level of the national health system makes a synthesis of its activities and sends this to the next higher level at defined regular intervals; monthly for routine data and daily for SIAs.

RESULTS

From 2004 to 2006 the national routine yellow fever vaccination coverage rose from 58.7% to 72.2%. In addition, the country achieved parity between yellow fever and measles vaccination coverage in 2005 and has since maintained this performance level. The number of suspected yellow fever cases in the country increased from 156 in 2003 to 859 in 2006, and the proportion of districts that reported at least one suspected yellow fever case per year increased from 31.4% to 68.2%, respectively. Blood specimens were collected from all suspected cases (within 14 days of onset of symptoms) and tested at a central laboratory for yellow fever IgM antibodies; leading to confirmation of yellow fever outbreaks in the health districts of Bafia, Méri and Ntui in 2003, Ngaoundéré Rural in 2004, Yoko in 2005 and Messamena in 2006. Owing to constraints in rapidly mobilising the necessary resources, reactive SIAs were only conducted in Bafia and Méri several months after confirmation of the outbreak. In both districts, a total of 60,083 people (representing 88.2% of the 68,103 targeted) were vaccinated. Owing to the same constraints, SIAs were not conducted promptly in response to the outbreaks in Ntui, Ngaoundéré Rural, Yoko and Messamena. However, these four and two other health districts at high risk of yellow fever outbreaks (i.e. Maroua Urban and Ngaoundéré Urban) conducted preventive SIAs in November 2006, vaccinating a total of 752,195 people (92.8% of target population). In both the reactive and preventive SIAs, the mean wastage rates for vaccines and injection material were less than 5% and there was no report of a serious adverse event following immunisation.

CONCLUSION

Amidst other competing health priorities, over the past four years Cameroon has successfully planned and implemented evidence-based strategies for preventing yellow fever outbreaks and for detecting and responding to the outbreaks when they occur. In order to sustain these initial successes, the country will have to attain and sustain high routine vaccination coverage in each successive birth cohort in every district. This would require fostering and sustaining high-level political commitment, improving the planning and monitoring of immunisation services at all levels, adequate community mobilisation, and efficient coordination of current and future immunisation partners.

Viral exanthems in the tropics

Viral exanthems are a common problem in tropical regions, particularly affecting children. Most exanthems are transient and harmless, but some are potentially very dangerous. Pregnant women and malnourished or immunocompromised infants carry the greatest risk of adverse outcome. In this article, parvovirus B19; dengue and yellow fever; West Nile, Barmah Forest, Marburg, and Ebola viruses, and human herpesviruses; asymmetric periflexural exanthema of childhood; measles; rubella; enteroviruses; Lassa fever; and South American hemorrhagic fevers will be discussed.

Deadly viral syndrome mimics

Upper respiratory tract infections (ie, "the common cold") have several hundred causes, the most common of which include rhino-virus, coronavirus, and respiratory syncytial virus. The clinical presentation varies with symptoms. Every emergency department, no matter what the demographics, cares for patients with this constellation of symptoms. Emergency physicians examine, diagnose, and treat these disorders frequently. With increasing burdens being placed on emergency physicians, it is possible to assume a diagnosis of upper respiratory tract infection without generating a complete differential diagnosis. The challenge is to identify and recognize the distinctions between an innocuous upper respiratory tract infection and a life-threatening disease "mimic" or entities. This article discusses some of these life-threatening mimics.

"Venerate the Lancet": Benjamin Rush's yellow fever therapy in context

In 1793, during a yellow fever epidemic in Philadelphia, Benjamin Rush adopted a therapy that centered on rapid depletion through purgation and bleeding. His method, especially his reliance on copious bloodletting, was at first widely condemned, but many American practitioners eventually adopted it. Although the therapy struck many observers as being radical, in large part it grew from premises that had substantial support. Rush was convinced that it worked and that heroic methods were the key to conquering disease. In particular, massive bleeding became central to his therapeutics.

[Yellow Fever]

Yellow fever is an infectious and non-contagious disease caused by an arbovirus, the yellow fever virus. The agent is maintained in jungle cycles among primates as vertebrate hosts and mosquitoes, especially Aedes in Africa, and Haemagogus and Sabethes in America. Approximately 90% of the infections are mild or asymptomatic, while 10% course to a severe clinical picture with 50% case-fatality rate. Yellow fever is largely distributed in Africa where urban epidemics are still reported. In South America, between 1970-2001, 4,543 cases were reported, mostly from Peru (51.5%), Bolivia (20.1%) and Brazil (18.7%). The disease is diagnosed by serology (detection of IgM), virus isolation, immunohistochemistry and RT-PCR. Yellow fever is a zoonosis and cannot be eradicated, but it is preventable in man by using the 17D vaccine. A single dose is enough to protect an individual for at least 10 years, after which revaccination is recommended. In this paper, the main concepts about yellow fever as well as the fatal adverse effects of the vaccine are updated.

Yellow fever: an update

Yellow fever, the original viral haemorrhagic fever, was one of the most feared lethal diseases before the development of an effective vaccine. Today the disease still affects as many as 200,000 persons annually in tropical regions of Africa and South America, and poses a significant hazard to unvaccinated travellers to these areas. Yellow fever is transmitted in a cycle involving monkeys and mosquitoes, but human beings can also serve as the viraemic host for mosquito infection. Recent increases in the density and distribution of the urban mosquito vector, Aedes aegypti, as well as the rise in air travel increase the risk of introduction and spread of yellow fever to North and Central America, the Caribbean and Asia. Here I review the clinical features of the disease, its pathogenesis and pathophysiology. The disease mechanisms are poorly understood and have not been the subject of modern clinical research. Since there is no specific treatment, and management of patients with the disease is extremely problematic, the emphasis is on preventative vaccination. As a zoonosis, yellow fever cannot be eradicated, but reduction of the human disease burden is achievable through routine childhood vaccination in endemic countries, with a low cost for the benefits obtained. The biological characteristics, safety, and efficacy of live attenuated, yellow fever 17D vaccine are reviewed. New applications of yellow fever 17D virus as a vector for foreign genes hold considerable promise as a means of developing new vaccines against other viruses, and possibly against cancers.

Impact of yellow fever on the developing world

Yellow fever (YF) has remained a disease of public health importance since it was first described in the fifteenth century. At different periods in human history, YF has caused untold hardship and indescribable misery among populations in the Americas, Europe, and Africa. It brought economic disaster in its wake, constituting a stumbling block to development. Yellow fever is an arboviral infection with three epidemiological transmission cycles between monkeys, mosquitoes, and humans. It is an acute infectious disease characterized by sudden onset, with two phases of development separated by a short period of remission. The clinical spectrum of YF varies from a very mild, nonspecific, febrile illness to a fulminating, sometimes fatal disease with pathognomonic features. In severe cases, jaundice and bleeding diathesis with hepatorenal involvement are common. The fatality rate of severe YF is 50% or higher. Despite landmark achievements in the understanding of the epidemiology of YF and the availability of a safe, efficacious vaccine, YF remains a major public health problem in both Africa and South America, where annually the disease affects an estimated 200,000 persons, causing an estimated 30,000 deaths. Since the 1980s epidemics of YF in Africa have affected predominantly children under the age of 15 years. The failure to control YF arises from a misapplication of public health strategies and insufficient political commitment by governments in YF endemic areas, especially in Africa, to control the disease.

Jungle yellow fever: clinical and laboratorial studies emphasizing viremia on a human case

The authors report the clinical, laboratorial and epidemiological aspects of a human case of jungle yellow fever. The patient suffered from fever, chills, sweating, headaches, backaches, myalgia, epigastric pains, nausea, vomiting, diarrhea and prostration. He was unvaccinated and had been working in areas where cases of jungle yellow fever had been confirmed. Investigations concerning the yellow fever virus were performed. Blood samples were collected on several days in the course of the illness. Three of these samples (those obtained on days 5, 7 and 10) were inoculated into suckling mice in attempt to isolate virus and to titrate the viremia level. Serological surveys were carried out by using the IgM Antibodies Capture Enzyme Linked Immunosorbent Assay (MAC-ELISA), Complement Fixation (CF), Hemagglutination Inhibition (HI) and Neutralization (N) tests. The yellow fever virus, recovered from the two first samples and the virus titration, showed high level of viremia. After that, specific antibodies appeared in all samples. The interval between the end of the viremia and the appearance of the antibodies was associated with the worsening of clinical symptoms, including bleeding of the mucous membrane. One must be aware of the risk of having a urban epidemics in areas where Aedes aegypti is found in high infestation indexes.

Mosquitoes, leeches and medicine in Charleston, South Carolina (1670-1861)

Charleston, South Carolina, USA has a rich history extending over 300 years. The plantations of the Carolina Low Country produced rice, indigo and cotton. Mosquitoes, which abounded in the wetlands, transmitted diseases such as Yellow Fever and epidemics occurred almost every year. African slaves, however, had a natural immunity to the disease and, together with the climate and the nature of the work, this shaped the economic and social system of the area. Physicians offered all sorts of cures to deal with the medical problems of the area and apothecaries also sold many nostrums including leeches. Newspaper advertisements reveal that these bloodsuckers were extensively used for many decades.

Scientific evaluation of clinical interventions in resuscitation medicine

The image of the physician as a therapist, as well as the general perception of the physician's role in society and in the life of patients and their families, has changed dramatically in past decades. In response, many conferences, editorials, and planning activities for medical and premedical curricula have been devoted to the subject of restoring the elements of compassion and personal involvement to the relationship between physician and patient. Nonetheless, the change in the doctor-patient relationship might merely reflect the growing indifference to people as individuals that seems to pervade our society in all service-related areas. Although the loss is particularly objectionable for the sick, some may claim it is compensated by scientifically superior care in present-day medical practice. This paper will reflect briefly on past and present views of medical care and its evaluation. It will conclude that a scientifically sound evaluation of treatment might also offer a solution for restoration of human elements in the delivery of medical care.

Effect of human gamma interferon on yellow fever virus infection

We studied yellow fever virus infection in two species of monkey: Saimiri sciureus (squirrel monkeys) and Macaca mulatta (rhesus monkeys). Human gamma interferon was administered intravenously in five equal doses, one was given 24 hr before infection followed by four doses 24 hr apart. Interferon reduced the levels and duration of viremia and the severity of hepatitis in squirrel monkeys. Interferon prolonged survival time and delayed the appearance of viremia and hepatitis in infected rhesus monkeys, but it did not change overall mortality.

Viral diseases involving the liver

Even though HAV, HBV and HNANB viruses are responsible for most of the viral hepatitis cases, many other viruses have been reported to cause hepatic injury. These viruses may involve the liver, either as part of a systemic illness (e.g. EBV, CMV, HSV) or as the primary target organ (e.g. yellow fever virus, Lassa fever virus, Ebola virus). Clinically overt hepatocellular dysfunction is rare in such viral infections. Biochemical disturbance of hepatic functions shown, for example, by rises in AST and ALT, is a frequent event and indicates hepatic damage. Morphological changes of the liver include varying degrees of hepatic necrosis with a paucity of inflammatory activities. Intranuclear or cytoplasmic inclusion bodies may be characteristic findings in these diseases. Laboratory diagnosis depends upon serology and liver histology. Treatment is still largely supportive in most of these diseases, although recent trials of antiviral agents show promise against some viruses. Chronic sequelae, such as cirrhosis or hepatocellular cancer, are not encountered. More work is needed to elucidate the pathogenesis of hepatic injury in these illnesses.

Yellow fever: a medically neglected disease. Report on a seminar

In 1984 the Pan American Health Organization (PAHO) sponsored an international seminar on the treatment and laboratory diagnosis of yellow fever. The meeting, held April 2-6 in Brasilia, was attended by 37 participants representing Bolivia, Brazil, Colombia, Peru, Venezuela, the United States, PAHO, and the World Health Organization. The objectives of the seminar were to review the current status of the disease, with emphasis on diagnosis and on the care and management of patients, and to formulate recommendations for improvements in diagnosis and management and for future research. A unique aspect of the seminar and one that distinguished it from previous, epidemiologically oriented meetings on yellow fever was the emphasis on clinical medicine and the participation of individuals representing academic medicine in relevant specialties such as hepatology, hematology, cardiology, and nephrology.