Vincent Pommier de Santi

Bio: Vincent Pommier de Santi is an academic researcher from Aix-Marseille University. The author has contributed to research in topics: Malaria & Medicine. The author has an hindex of 15, co-authored 57 publications receiving 611 citations.

Malaria in French Guiana Linked to Illegal Gold Mining

Abstract: To the Editor: French Guiana, an overseas territory of France and part of the European Union, is located on the northeast coast of South America (Figure). During 2008– 2014, the number of malaria cases reported in French Guiana drastically decreased (1). The littoral area (≈30 km–wide Atlantic Ocean coastal band between the cities of Awala-Yalimapo and Ouanary) and the lower part of the Maroni River bordering Suriname (between the cities of Maripasoula and Saint-Laurent du Maroni) are considered malaria free, but this status may not reflect malaria transmission in the inland rainforest (2–4). Since 2008, French Armed Forces have been involved in military operations to control and reduce illegal gold mining activities in forested areas. Soldiers and military policemen usually spend 1–3 weeks in illegal gold mining sites in remote rainforest areas before returning to the littoral area or to bases on rivers bordering Suriname and Brazil. Despite malaria prevention strategies (5), these deployments have resulted in several outbreaks and increased malaria incidence among French forces (6). Most malaria episodes occurred during or just after deployments, so presumed locations of exposure can be easily identified. Figure Geographic distribution of presumed places of exposure for 742 single-infection Plasmodium vivax (586) and P. falciparum (156) malaria cases reported among French Armed Forces in French Guiana, 2008–2014. Numbers on map show illegal gold mining ... Information about malaria cases was collected during 2008–2014 by the French Armed Forces’ epidemiologic surveillance system by using a mandatory, specific form that captured putative place of malaria exposure and biologic data for case-patients (6). Geographic coordinates of presumed places of contamination were uploaded into a geographic information system (ArcGIS; http://www.esri.com/software/arcgis/) to produce a malaria distribution map. During 2008–2014, a total of 1,070 malaria cases were reported to the French Armed Forces’ epidemiologic surveillance system. Plasmodium vivax accounted for 78.8% (843/1,070), P. falciparum for 18.0% (193/1,070), and mixed infection (P. vivax and P. falciparum) for 3.2% (34/1,070). Places where malaria exposure occurred were identified for 742 cases of single malaria (586 P. vivax and 156 P. falciparum) infections (Figure). Cases occurring along the Maroni and Oyapock Rivers delimiting the frontiers with Suriname and Brazil, respectively, accounted for 25.3% (188/742). The other cases (74.7%, 554/742) were associated with exposures during military operations in illegal gold mining sites. Entomologic investigations were conducted in 2 malaria epidemic locations where French forces were deployed: Eau-Claire and Dagobert. Collected Anopheles spp. mosquito specimens were identified by using morphologic keys specific to the Guyana Shield, a geomorphologic formation underlying French Guiana and other areas (7). Nonidentifiable Anopheles mosquito specimens were further identified molecularly (8). PCR products from the internal transcribed spacer 2 gene were sequenced, and Anopheles species were identified by comparing sequences to those in GenBank (http://www.ncbi.nlm.nih.gov/genbank/) by searching with BLAST (http://blast.ncbi.nlm.nih.gov/Blast.cgi). Testing for P. falciparum and P. vivax infections was conducted for all Anopheles spp. specimens by using nested PCR, as described (9). In May 2013, a malaria outbreak occurred 1 month after military deployment of 100 soldiers at Eau Claire (3.56075°N, −53.21268°E; Figure), where 1 Mosquito Magnet trap (Woodstream Corporation, Lititz, PA, USA) baited with octenol was used to sample Anopheles mosquitoes during April 22–May 12, 2013 (10). The attack rate among the soldiers was 5.0% (5/100): 4 P. vivax and 1 P. falciparum malaria cases. Fifty-three Anopheles mosquito specimens were caught during the 20 days before the outbreak and identified as comprising 4 species (Technical Appendix Table). P. falciparum infection was detected in 2 Anopheles species: 1 (12.5%) of 8 An. ininii and 1 (5.0%) of 19 An. nuneztovari s.l. mosquitoes collected; P. vivax infection was found in 1 (5.5%) of 19 An. nuneztovari s.l. mosquitoes. In September 2013, another malaria outbreak occurred 3 weeks after the deployment of 15 soldiers in Dagobert (4.06028°N, −53.70667°E; Figure). The attack rate among these soldiers was 53.3% (8/15): 7 P. vivax infections and 1 co-infection with P. vivax and P. falciparum. Mosquitoes were collected 3 months later by using human landing catches during 5 consecutive days. The area had been free of illegal gold mining activities since the 15 soldiers were deployed. A total of 321 Anopheles mosquitoes were collected in this location; 95.6% were identified as the same 4 species as in the Eau Claire mosquito collection (Technical Appendix Table). Only 1 specimen (0.4%, 1/282), An. darlingi mosquito, was infected with P. vivax. These results suggest a high level of malaria transmission involving An. darlingi and other Anopheles species as primary vectors of malaria in the rainforest. The findings probably highlight malaria hyperendemicity in communities of undocumented gold miners, who are often mobile and pose a challenge for controlling malaria and other infectious diseases in the region. Indeed, these gold miners could reintroduce malaria in areas where competent vectors exist in the coastal part of French Guiana and in Surinam and Brazil, which border French Guiana. This potential for transmission could seriously threaten the success of malaria elimination programs in the Guiana Shield. Further studies are needed to better evaluate malaria epidemiology in these undocumented populations to determine how best to adapt strategies to control malaria transmission in this subregion of South America. Technical Appendix: The distribution of mosquitoes sampled by sampling sites and Plasmodium infection rates of the 374 Anopheles mosquitoes caught in the French Guiana forest, 2013 Click here to view.(72K, pdf)

Epidemiological and entomological studies of a malaria outbreak among French armed forces deployed at illegal gold mining sites reveal new aspects of the disease’s transmission in French Guiana

Abstract: Background In December 2010, a Plasmodium vivax malaria outbreak occurred among French forces involved in a mission to control illegal gold mining in French Guiana. The findings of epidemiological and entomological investigations conducted after this outbreak are presented here.

Three-toed sloth as putative reservoir of Coxiella burnetii, Cayenne, French Guiana.

Abstract: To the Editor: Q fever is an emerging zoonosis and a major public health concern in French Guiana, a French overseas region located on the northeastern coast of South America (1,2). Most cases occur in the city of Cayenne (3), specifically in the suburbs, where houses are near wooded hills (4). Genotyping performed by using multispacer sequence typing showed that MST17, a unique genotype of C. burnetii, circulates in Cayenne and is responsible for epidemics of Q fever (5). C. burnetii transmission peaks during the rainy season, and the incidence of Q fever usually increases 1–3 months later (6). The animal reservoir of C. burnetii in French Guiana is unknown; previous studies have excluded domestic ruminants, which are known to be C. burnetii reservoirs elsewhere in the world (6). Four serologic surveys showed few C. burnetii–positive opossums, dogs, rodents (Proechimys spp.), bovines, or birds in French Guiana (7). In 2013, using real-time PCR (qPCR) analysis of vaginal swab samples, we showed that 6/158 (3.8%) dogs from Cayenne and 0/206 bats from the coastal area of French Guiana were positive for C. burnetii (cycle threshold [Ct]<35). One of the positive samples was identified as genotype MST17 (5). A case–control study among humans identified several risk factors for Q fever, including living near a forest and the presence of wild animals near the house (6). During January–April 2013, a Q fever outbreak occurred in Tiger Camp, a military residential area located at the top of a wooded hill in Cayenne. Vaginal swab samples were collected from animals living in the area (13 goats, 8 sheep, 7 bats, 34 birds, 2 opossums, 4 iguanas, and 17 geckos); all samples were negative for C. burnetii by qPCR. In addition, serologic tests for C. burnetii were negative for samples from all 37 small ruminants maintained near the outbreak area. In January 2014, a dead (accidental death) female 3-toed sloth (Bradypus tridactylus) (Figure, panel A) was found on the road near the residence of a Q fever patient. We retrieved the sloth and collected feces, spleen, liver, kidney, lung, and uterus samples and a vaginal swab sample. A total of 16 ticks were removed from the sloth and stored in 70% alcohol. Figure Putative reservoir of Coxiella burnetii in Cayenne, French Guiana A) A 3-toed sloth (Bradypus tridactylus) in its natural habitat in Tiger Camp, a military residential area located at the top of a wooded hill in Cayenne, French Guiana (photograph by S. ... DNA was extracted from the feces, organs, and ticks by using the BioRobot EZ1 Workstation (QIAGEN, Courtaboeuf, France). qPCR targeting the repeated insertion sequence IS1111 was performed by using a CFX96 Touch Real-Time PCR Detection System (Bio-Rad, Marne la Coquette, France) as described (8). We confirmed all positive results by performing a second qPCR targeting the IS30a repeated sequence. DNA samples with Ct values <35 in both assays were considered positive for C. burnetii. A standard calibration curve quantifying the target IS1111 was generated by using 10-fold serial dilutions of C. burnetii Nine Mile strain. The number of IS1111 intergenic sequences found in the genome of strain C. burnetii MST17 was identical to that for the Nine Mile strain (F. D’Amato, unpub. data); thus, the qPCR that we used was valid for quantifying the number of C. burnetii MST17 IS1111 copies/mL in samples we collected (5). qPCR analysis showed that the feces were highly positive for C. burnetii; the sample had a low Ct value of 23, corresponding to 7 log10 DNA copies/mL (9). The spleen was also positive for C. burnetii; the Ct value was 34, corresponding to 3.6 log10 DNA copies/mL. Results for the other samples were negative. Using morphologic criteria, we identified all 16 ticks collected from the sloth as Amblyomma geayi (Figure, panel B). We performed C. burnetii–specific qPCR on the ticks; 14 (88%) were positive. We genotyped C. burnetii–positive DNA from the feces and from 6 of the 16 ticks by using multispacer sequence typing as described (5). All samples were identified as MST17, the unique genotype circulating in Cayenne (5). After obtaining the laboratory results, we confirmed that a local group in charge of the collection and treatment of injured animals usually released rehabilitated 3-toed sloths into Tiger Camp. Residents of Tiger Camp regularly observed and came into contact with the sloths, and ticks were frequently observed on the fur of the animals. Furthermore, 3 Q fever patients from Cayenne reported contact with sloths. Feces from the sloth in this study were highly infectious for C. burnetii. Because sloths live in tall trees and can shed this bacterium in their feces, human contamination might occur through inhalation of infectious aerosols from feces. The high prevalence of C. burnetii infection in ticks also suggests possible transmission through tick bites or from aerosols of tick feces that have been deposited on the skin of animal hosts; such feces can be extremely rich in bacteria and highly infectious (10). In this 2013 outbreak of Q fever, epidemiologic studies led to the identification of 3-toed sloths as a putative source of C. burnetii infection. Further investigations are needed to confirm the role of sloths as a reservoir for C. burnetii in French Guiana and to implement efficient measures to prevent transmission to humans.

Malaria Hyperendemicity and Risk for Artemisinin Resistance among Illegal Gold Miners, French Guiana.

Abstract: To assess the prevalence of malaria among illegal gold miners in the French Guiana rainforest, we screened 205 miners during May-June 2014. Malaria prevalence was 48.3%; 48.5% of cases were asymptomatic. Patients reported self-medication with artemisinin-based combination therapy. Risk for emergence and spread of artemisinin resistance among gold miners in the rainforest is high.

Malakit: an innovative pilot project to self-diagnose and self-treat malaria among illegal gold miners in the Guiana Shield.

Abstract: Illegal gold miners in French Guiana, a French overseas territory (‘departement’) located in Amazonia, often carry malaria parasites (up to 46.8%). While the Guiana Shield Region aims at malaria elimination, the high prevalence of Plasmodium in this hard-to-reach population in conjunction with frequent incorrect use of artemisinin-based anti-malarials could favour the emergence of resistant parasites. Due to geographical and regulatory issues in French Guiana, usual malaria control strategies cannot be implemented in this particular context. Therefore, new strategies targeting this specific population in the forest are required. Numerous discussions among health institutions and scientific partners from French Guiana, Brazil and Suriname have led to an innovative project based on the distribution of kits for self-diagnosis and self-treatment of Plasmodium infections. The kit-distribution will be implemented at “resting sites”, which are areas across the border of French Guiana regularly frequented by gold miners. The main objective is to increase the appropriate use and complete malaria treatment after a positive malaria diagnosis with a rapid test, which will be evaluated with before-and-after cross-sectional studies. Monitoring indicators will be collected from health mediators at the time of kit distribution and during subsequent visits, and from illegal gold miners themselves, through a smartphone application. The project funding is multisource, including Ministries of Health of the three countries, WHO/PAHO, and the European Union. This project will start in April 2018 as a 18 month pilot study led by the Clinical Investigation Centre of Cayenne. Results should be available at the end of 2019. This innovative approach may have several limitations which should be taken into account, as potential side effects, kit misuse or resale, declarative main criteria, or no Plasmodium vivax curative treatment. Close monitoring is thus needed. This project may be the best available solution to a specific and important public health challenge in the Guiana Shield. If the use of self-diagnosis and self-treatment approach is effective, this strategy could be sustained by health institutions in the region.

From Q Fever to Coxiella burnetii Infection: a Paradigm Change.

Abstract: Coxiella burnetii is the agent of Q fever, or ``query fever,'' a zoonosis first described in Australia in 1937. Since this first description, knowledge about this pathogen and its associated infections has increased dramatically. We review here all the progress made over the last 20 years on this topic. C. burnetii is classically a strict intracellular, Gram-negative bacterium. However, a major step in the characterization of this pathogen was achieved by the establishment of its axenic culture. C. burnetii infects a wide range of animals, from arthropods to humans. The genetic determinants of virulence are now better known, thanks to the achievement of determining the genome sequences of several strains of this species and comparative genomic analyses. Q fever can be found worldwide, but the epidemiological features of this disease vary according to the geographic area considered, including situations where it is endemic or hyperendemic, and the occurrence of large epidemic outbreaks. In recent years, a major breakthrough in the understanding of the natural history of human infection with C. burnetii was the breaking of the old dichotomy between ``acute'' and ``chronic'' Q fever. The clinical presentation of C. burnetii infection depends on both the virulence of the infecting C. burnetii strain and specific risks factors in the infected patient. Moreover, no persistent infection can exist without a focus of infection. This paradigm change should allow better diagnosis and management of primary infection and long-term complications in patients with C. burnetii infection.

Enteric protozoa in the developed world: a public health perspective.

Abstract: SUMMARY Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.

Alternative strategies for mosquito-borne arbovirus control.

Abstract: Background: Mosquito-borne viruses—such as Zika, chikungunya, dengue fever, and yellow fever, among others—are of global importance. Although vaccine development for prevention of mosquito-borne arbovirus infections has been a focus, mitigation strategies continue to rely on vector control. However, vector control has failed to prevent recent epidemics and arrest expanding geographic distribution of key arboviruses, such as dengue. As a consequence, there has been increasing necessity to further optimize current strategies within integrated approaches and advance development of alternative, innovative strategies for the control of mosquito-borne arboviruses. Methods and findings: This review, intended as a general overview, is one of a series being generated by the Worldwide Insecticide resistance Network (WIN). The alternative strategies discussed reflect those that are currently under evaluation for public health value by the World Health Organization (WHO) and represent strategies of focus by globally recognized public health stakeholders as potential insecticide resistance (IR)-mitigating strategies. Conditions where these alternative strategies could offer greatest public health value in consideration of mitigating IR will be dependent on the anticipated mechanism of action. Arguably, the most pressing need for endorsement of the strategies described here will be the epidemiological evidence of a public health impact. Conclusions: As the burden of mosquito-borne arboviruses, predominately those transmitted by Aedes aegypti and A. albopictus, continues to grow at a global scale, new vector-control tools and integrated strategies will be required to meet public health demands. Decisions regarding implementation of alternative strategies will depend on key ecoepidemiological parameters that each is intended to optimally impact toward driving down arbovirus transmission.

Challenges for malaria elimination in Brazil

Abstract: Brazil currently contributes 42 % of all malaria cases reported in the Latin America and the Caribbean, a region where major progress towards malaria elimination has been achieved in recent years. In 2014, malaria burden in Brazil (143,910 microscopically confirmed cases and 41 malaria-related deaths) has reached its lowest levels in 35 years, Plasmodium falciparum is highly focal, and the geographic boundary of transmission has considerably shrunk. Transmission in Brazil remains entrenched in the Amazon Basin, which accounts for 99.5 % of the country’s malaria burden. This paper reviews major lessons learned from past and current malaria control policies in Brazil. A comprehensive discussion of the scientific and logistic challenges that may impact malaria elimination efforts in the country is presented in light of the launching of the Plan for Elimination of Malaria in Brazil in November 2015. Challenges for malaria elimination addressed include the high prevalence of symptomless and submicroscopic infections, emerging anti-malarial drug resistance in P. falciparum and Plasmodium vivax and the lack of safe anti-relapse drugs, the largely neglected burden of malaria in pregnancy, the need for better vector control strategies where Anopheles mosquitoes present a highly variable biting behaviour, human movement, the need for effective surveillance and tools to identify foci of infection in areas with low transmission, and the effects of environmental changes and climatic variability in transmission. Control actions launched in Brazil and results to come are likely to influence control programs in other countries in the Americas.