New guidelines for the prevention of imported malaria in France.

Prevention of malaria is based on personal vector-control measures (PVCMs) to avoid mosquito bites at night and chemoprophylaxis if justified by the risk of contracting the disease. The most effective PVCM is the use of insecticide-treated mosquito nets. The decision to prescribe chemoprophylaxis, mainly to prevent Plasmodium falciparum infection, depends on the benefit-risk ratio. Overall, the risk of contracting malaria is 1,000-fold lower during a stay in the tropical regions of Asia or the Americas than in sub-Saharan Africa. For "conventional" stays (less than one month with nights spent in urban areas) in low-risk settings in tropical Asia and America, the risk of being infected with Plasmodium parasites (≤1/100,000) is equivalent or lower than that of experiencing serious adverse effects caused by chemoprophylaxis. Preventive medication is therefore no longer recommended. By contrast, in other settings and particularly in sub-Saharan Africa, chemoprophylaxis is the most effective measure against malaria. However, it is worth noting that no single preventive measure provides full protection. Regardless of the level of risk or chemoprophylaxis-related indication, protection against mosquito bites and rapid management of febrile illness after returning from an endemic area are also critical to prevent malaria. Finally, migrants of sub-Saharan origin visiting friends and relatives in their country of origin form a high-risk group who should be recommended chemoprophylaxis in the same way as any other travelers-with a preference for the least expensive molecules (doxycycline).

Acquisition of carbapenemase-producing Enterobacteriaceae by healthy travellers to India, France, February 2012 to March 2013.

Healthy travellers to countries where carbapenemases-producing Enterobacteriaceae (CPE) are endemic might be at risk for their acquisition, even without contact with the local healthcare system. Here, we report the acquisition of CPE (two OXA-181, one New Delhi metallo-beta-lactamase 1 (NDM-1)) in three healthy travellers returning from India. The duration of CPE intestinal carriage was less than one month. The results indicate that healthy travellers recently returning from India might be considered as at risk for CPE carriage.

Persistence of yellow fever vaccine-induced antibodies after solid organ transplantation.

Immunization using live attenuated vaccines represents a contra-indication after solid organ transplantation (SOT): consequently, transplant candidates planning to travel in countries where yellow fever is endemic should be vaccinated prior to transplantation. The persistence of yellow fever vaccine-induced antibodies after transplantation has not been studied yet. We measured yellow-fever neutralizing antibodies in 53 SOT recipients vaccinated prior to transplantation (including 29 kidney recipients and 18 liver recipients). All but one (98%) had protective titers of antibodies after a median duration of 3 years (min.: 0.8, max.: 21) after transplantation. The median antibody level was 40 U/L (interquartile range: 40-80). For the 46 patients with a known or estimated date of vaccination, yellow-fever antibodies were still detectable after a median time of 13 years (range: 2-32 years) post-immunization. Our data suggest there is long-term persistence of antibodies to yellow fever in SOT recipients who have been vaccinated prior to transplantation.

[Long term persistence of yellow fever neutralising antibodies in elderly persons]. / Persistance à long terme des anticorps neutralisants de la fièvre jaune chez les personnes âgées de 60 ans et plus.

The activity of the yellow fever virus is reemerging in areas without recent transmission history, such as northern Argentina and Paraguay, and persists in an epidemic mode in other countries in Africa and Latin America. Thus more and more travelers are at risk of being exposed to this disease. The population is becoming older, sometimes suffering from multiple pathologies. Moreover, the risk of serious adverse events associated with live-attenuated YF17D vaccine, such as multiple organ failure (YEL-AVD), reaches 1/50,000 vaccines in people over 65 versus 1/200,000 in the general population. We analyzed, in a retrospective study, the results of neutralizing antibody titers against yellow fever in people aged 60 and older, who had been previously vaccinated against yellow fever and had visited the International Vaccination Centre of the Institut Pasteur between January 2005 and February 2009. In this population of 84 persons (median age 69 years), the date of the last vaccination was always more than 10 years: it was precisely known in 68 subjects and alleged in 16 subjects. The median time since the previous vaccination was 14 years, with a maximum of 60 years. The indications of serology were: immunosuppressive therapy (19% of cases), cancer (32%), hemopathy (10.7%), HIV infection (3.6%), chronic hepatitis/chronic renal failure/dialysis (2.4%), autoimmune diseases (2.4%), and in 29.8% of cases, age alone was the indication of serology. The antibody titer was at a protective level in 95.2% of cases. The four individuals with negative serology had no formal documented proof of a previous vaccination against yellow fever. This serological study was able to show a persistent protective antibody titer, after a previous vaccination, even going back 60 years, allowing patients to travel in a yellow-fever endemic area despite a contraindication, and without requiring any vaccine booster.

[Long-term seroprotection against Japanese encephalitis using an inactivated vaccine (Jevax)]. / Séroprotection à long terme avec le vaccin inactivé contre l'encéphalite japonaise (Jevax).

Japanese encephalitis vaccine (Jevax) is an inactivated vaccine using the Nakayama viral strain. Until 2007, Jevax was the only Japanese encephalitis vaccine available in France but the duration of seroprotection after vaccination and exact timing of booster injections was unclear for travelers from non-endemic areas. The purpose of this report is to describe the results of a retrospective study in which neutralizing antibody levels were measured in 71 subjects previously vaccinated with Jevax. All subjects underwent testing at the Pasteur Institute Medical Center as part of preparation for humanitarian missions to endemic Japanese encephalitis areas in 2005-2006. A neutralizing antibody level greater than or equal to 20 was considered as protective. Findings showed that 49 of the 71 subjects (69%) still had protective antibody levels at a median of 4 years after the last Jevax immunization. In multivariate analysis, the only factor correlated with long-term seroprotection was the total number of vaccinations received. Based on these findings, it was concluded that long-term seroprotection after Jevax vaccination requires repeated booster injections even in subjects frequently exposed to the virus. No correlation was found between seroprotection and the interval between the booster injections.

[Vaccinations for the traveling adult solid organ transplant recipient (excluding hematopoietic stem cell transplant recipients)]. / Vaccinations du voyageur adulte transplanté d'organes (à l'exclusion des receveurs de cellules souches hématopoïétiques).

Progress in transplantation technique has offered a growing number of solid organ transplant recipients the opportunity to travel to tropical and low-income countries. The issue of vaccine-preventable diseases is a challenging question in immunocompromised patients including those with solid organ transplant. Since the response to vaccines is weakened in case of chronic organ failure, candidates should be vaccinated early in the course of the disease. Clinicians should implement a vaccinal strategy until the patient is scheduled for transplantation and monitor its efficacy by serological assays. Live attenuated vaccines (such as yellow fever, measles-mumps-rubella, or chicken pox) are contra-indicated in solid organ transplant recipients and, when indicated, should be administered prior to transplantation, particularly in foreign-born patients highly likely to visit friends and relatives in endemic areas. Vaccinations for transplant recipients considering international travel should be realized according to the risk of acquiring vaccine-preventable diseases but also on both tolerance and immune response which are affected by degree and duration of immunosuppression, comorbidities, and type of organ transplanted. Routine and specific vaccinations for solid organ transplant recipients, as well as travel-related vaccination (such as hepatitis A, typhoid, meningococcal meningitis, rabies, tick-born encephalitis, Japanese encephalitis, and cholera) should be considered during a specific pretravel medical consultation. However, vaccination should be avoided in the 6 months following transplantation when patients are usually receiving the highest doses of immunosuppressive drugs. In this comprehensive review, we provide vaccination schedules based on published studies and guidelines for vaccination of solid organ transplant recipients.

[Antiviral immunization of immunocompromised adults, literature review]. / Vaccination antivirale des adultes immunodéprimés, revue de la littérature.

PURPOSE: Immunization, by preventing infections, has a major interest for the immunocompromised subjects. The aim of this article is to make a point on data concerning efficacy (in terms of immunogenicity) and safety of viral vaccines available in France and to synthesize existing guidelines for four groups of patients: solid organ and hematopoietic stem cell transplant recipients, HIV infected persons and patients treated by immunosuppressive drugs for a systemic disease. CURRENT KNOWLEDGE AND KEY POINTS: Available data about vaccines immunogenicity and safety for immunocompromised adults are rare. However, those data indicate that, when immunization contraindications and recommendations are applied, vaccines remain well tolerated and most of the time immunogenic, even if the percentage of responders is lower compared to non immunocompromised persons. Still, the specific guidelines that have been elaborated for immunization of immunocompromised adults are imprecise and incomplete, emphasizing a lack of data about this topic. FUTURE PROSPECTS: Clinical studies remain necessary to precise vaccines immunogenicity and safety for immunocompromised adults. In the meantime, a harmonization of immunization practices for immunocompromised adults should be proposed, so as to help practitioners to succeed a better immunization coverage for these patients.

High prevalence of co-factor independent anticardiolipin antibodies in malaria exposed individuals.

Anticardiolipin antibodies (aCL) were investigated in 137 individuals chronically exposed to malaria and living in Africa and Asia. They belonged to several groups according to parasite (Plasmodium falciparum or vivax) and clinical manifestations (i.e. asymptomatic parasite carriers, acute uncomplicated attack or severe malaria episodes). aCL were measured in an enzyme immunoassay (ELISA) performed in the presence of either goat serum (aCLs) or gelatin (aCLg). In a group of 53 patients with autoimmune manifestations (i.e. antiphospholipid syndrome and/or lupus), detection of IgG but not IgM aCL was markedly reduced in the presence of gelatin. In malaria donors, high prevalence of serum co-factor-independent IgG and IgM were detected, and the presence of goat serum in the assay consistently decreased their detection. aCLg levels were found to be related to the clinical/endemic status of donors. IgG aCLg were found to be higher in asymptomatic P. falciparum carriers than in patients with uncomplicated acute or cerebral malaria. IgM aCLg were higher in the cerebral malaria group than in groups with uncomplicated acute malaria patients or asymptomatic individuals. Data suggest that using a serum co-factor independent, sensitive ELISA, aCL are commonly detected during malarial infections and related to malarial infection status.