RESUMEN

BACKGROUND: In light of the 2016 summer Olympic games it is anticipated that Canadian practitioners will require information about common illnesses that may affect travellers returning from Brazil. OBJECTIVE: To identify the demographic and travel correlates of illness among recent Canadian travellers and migrants from Brazil attending a network of travel health clinics across Canada. METHODS: Data was analyzed on returned Canadian travellers and migrants presenting to a CanTravNet site for care of an illness between June 2013 and June 2016. RESULTS: During the study period, 7,707 ill travellers and migrants presented to a CanTravNet site and 89 (0.01%) acquired their illness in Brazil. Tourists were most well represented (n=45, 50.6%), followed by those travelling to "visit friends and relatives" (n=14, 15.7%). The median age was 37 years (range <1-78 years), 49 travellers were men (55.1%) and 40 were women (44.9%). Of the 40 women, 26 (65%) were of childbearing age. Nine percent (n=8) of travellers were diagnosed with arboviruses including dengue (n=6), chikungunya (n=1) and Zika virus (n=1), while another 14.6% (n=13) presented for care of non-specific viral syndrome (n=7), non-specific febrile illness (n=1), peripheral neuropathy (n=1) and non-specific rash (n=4), which are four syndromes that may be indicative of Zika virus infection. Ill returned travellers to Brazil were more likely to present for care of arboviral or Zika-like illness than other ill returned travellers to South America (23.6 per 100 travellers versus 10.5 per 100 travellers, respectively [p=0.0024]). INTERPRETATION: An epidemiologic approach to illness among returned Canadian travellers to Brazil can inform Canadian practitioners encountering both prospective and returned travellers to the Olympic games. Analysis showed that vector-borne illnesses such as dengue are common and even in this small group of travellers, both chikungunya and Zika virus were represented. It is extremely important to educate travellers about mosquito-avoidance measures in advance of travel to Brazil.

RESUMEN

Anopheles albimanus and An. pseudopunctipennis differ in their susceptibilities to Plasmodium vivax circumsporozoite phenotypes. An. pseudopunctipennis is susceptible to phenotype VK247 but almost refractory to VK210. In contrast, An. albimanus is almost refractory to VK247 but susceptible to VK210. To investigate the site in the mosquito and the parasite stage at which resistance mechanisms affect VK247 development in An. albimanus, parasite development was followed in a series of experiments in which both mosquitoes species were simultaneously infected with blood from patients. Parasite phenotype was determined in mature oocysts and salivary gland sporozoites by use of immunofluorescence and Western blot assays and/or gene identification. Ookinete maturation and their densities within the bloodmeal bolus were similar in both mosquito species. Ookinete densities on the internal midgut surface of An. albimanus were 4.7 times higher than those in An. pseudopunctipennis; however, the densities of developing oocysts on the external midgut surface were 6.12 times higher in the latter species. Electron microscopy observation of ookinetes in An. albimanus midgut epithelium indicated severe parasite damage. These results indicate that P. vivax VK247 parasites are destroyed at different parasite stages during migration in An. albimanus midguts. A portion, accumulated on the internal midgut surface, is probably destroyed by the mosquito's digestive enzymes and another portion is most likely destroyed by mosquito defense molecules within the midgut epithelium. A third group, reaching the external midgut surface, initiates oocyst development, but over 90% of them interrupt their development and die. The identification of mechanisms that participate in parasite destruction could provide new elements to construct transgenic mosquitoes resistant to malaria parasites.

Asunto(s)

Anopheles/parasitología , Insectos Vectores/parasitología , Plasmodium vivax/fisiología , Proteínas Protozoarias/fisiología , Animales , Anopheles/inmunología , Femenino , Insectos Vectores/inmunología , Microscopía Electrónica , Fenotipo , Plasmodium vivax/crecimiento & desarrollo , Plasmodium vivax/inmunología , Plasmodium vivax/ultraestructura , Proteínas Protozoarias/química , Proteínas Protozoarias/genética

RESUMEN

The geographic distribution of Plasmodium vivax circumsporozoite protein phenotypes from patient blood used to infect colonized Anopheles albimanus and An. pseudopunctipennis was investigated in southern Mexico. Parasite phenotype types were determined in blood samples by a polymerase chain reaction and oligoprobe hybridization or by immunofluorescent assay of sporozoites. The proportion of infected mosquitoes and the number of oocysts per mosquito confirmed previous in vitro observations indicating that An. albimanus is more susceptible to VK210 and that An. pseudopunctipennis is more susceptible to VK247. All patients living on the coast were infected with VK210 and most patients living above 170 meters above sea level had VK247. Both phenotypes infected patients from intermediate altitudes. These results concur with the distribution of the anophelines, indicating that An. albimanus is the main vector of the phenotype VK210, but that An. pseudopunctipennis transmits both phenotypes. These conditions have direct implications on parasite transmission rates and malaria epidemiology in Mexico.

Asunto(s)

Anopheles/parasitología , Insectos Vectores/parasitología , Malaria Vivax/epidemiología , Plasmodium vivax/clasificación , Altitud , Animales , Anticuerpos Monoclonales , Anticuerpos Antiprotozoarios/análisis , Antimaláricos/uso terapéutico , Cloroquina/uso terapéutico , Cartilla de ADN/química , ADN Protozoario/química , ADN Protozoario/aislamiento & purificación , Femenino , Fluoroinmunoensayo , Humanos , Malaria Vivax/sangre , Malaria Vivax/parasitología , Masculino , México/epidemiología , Hibridación de Ácido Nucleico , Fenotipo , Plasmodium vivax/química , Plasmodium vivax/genética , Reacción en Cadena de la Polimerasa , Prevalencia , Primaquina/uso terapéutico , Recurrencia , Análisis de Regresión

RESUMEN

The susceptibilities to coindigenous Plasmodium vivax of colonized Anopheles albimanus and Anopheles pseudopunctipennis from southern Mexico were investigated by simultaneous feeding with infected blood obtained from patients. The genes encoding circumsporozoite protein variant types (VK210 and VK247) in blood samples were determined by PCR and oligonucleotide probe hybridization. A. albimanus was more susceptible to VK210, and A. pseudopunctipennis was more susceptible to VK247.

Asunto(s)

Anopheles/parasitología , Insectos Vectores/parasitología , Malaria Vivax/parasitología , Plasmodium vivax/inmunología , Animales , Anopheles/inmunología , Anopheles/fisiología , Variación Antigénica , Antígenos de Protozoos/genética , Susceptibilidad a Enfermedades , Humanos , Inmunidad Innata , Insectos Vectores/inmunología , Insectos Vectores/fisiología , Modelos Logísticos , Malaria Vivax/inmunología , Malaria Vivax/transmisión , México , Plasmodium vivax/genética , Proteínas Protozoarias/genética

RESUMEN

The presence of chloroquine-resistant Plasmodium vivax malaria in the New World has been suspected but not confirmed. We report the cases of three patients who acquired vivax malaria in Guyana, South America, and for whom standard chloroquine therapy (25 mg/kg) failed despite therapeutic blood levels. The optimal treatment of chloroquine-resistant P. vivax malaria is unknown, but recent studies suggest that a combination of chloroquine (25 mg/kg) and high-dose primaquine (2.5 mg/kg over 48 hours) is effective therapy. Two of our patients had recurrences of P. vivax malaria 6-8 weeks after receiving directly observed therapy with this combination. These cases confirm the presence of chloroquine-resistant P. vivax in Guyana and emphasize the need for better treatment regimens for chloroquine-resistant and primaquine-resistant P. vivax malaria.

Asunto(s)

Cloroquina/uso terapéutico , Malaria Vivax/tratamiento farmacológico , Plasmodium vivax/efectos de los fármacos , Primaquina/uso terapéutico , Adulto , Animales , Quimioterapia Combinada , Estudios de Seguimiento , Guyana , Humanos , Masculino , Plasmodium vivax/aislamiento & purificación , Insuficiencia del Tratamiento

RESUMEN

The presence of chloroquine-resistant Plasmodium vivax malaria in the New World has been suspected but not confirmed. We report the cases of three patients who acquired vivax malaria in Guyana, South America, and for whom standard chloroquine therapy (25mg/kg) failed despite therapeutic blood levels. The optimal treatment of Chloroquine-resistant P. vivax malaria is unknown, but recent studies suggest that a combination of chloroquine (25 mg/kg) and high-dose primaquine (2.5 mg/kg over 48 hours) is effective therapy. Two of our patients had recurrences of P. vivax malaria 6-8 weeks after receiving directly observed therapy with this combination. These cases confirm the presence of chloroquine-resistant P. vivax in Guyana and emphasize the need for better treatment regimens for chloroquine-resistant and primaquine-resistant P. vivax malaria.(AU)

Asunto(s)

Informes de Casos , Adulto , 21003 , Humanos , Masculino , Cloroquina/uso terapéutico , Malaria Vivax/tratamiento farmacológico , Plasmodium vivax/efectos de los fármacos , Primaquina/uso terapéutico , Quimioterapia Combinada , Estudios de Seguimiento , Guyana , Plasmodium vivax/aislamiento & purificación , Insuficiencia del Tratamiento

RESUMEN

Two variants of the circumsporozoite (CS) protein of Plasmodium vivax (VK210 and VK247) have been identified. Recently, a putative third CS variant of P. vivax, referred to as causing P. vivax-like malaria, has been reported from Papua New Guinea. The objective of this study was to confirm and extend findings on the global distribution of the P. vivax-like parasite. Blood samples were obtained from 126 untreated patients with P. vivax infection acquired in Central America, South America, Africa, Southeast Asia, and the Indian subcontinent. The P. vivax CS gene was amplified by polymerase chain reaction and hybridized with probes specific for the VK210, VK247, and P. vivax-like CS variants. All samples were positive for VK210, VK247, or both. No sample was positive for P. vivax-like DNA. Therefore, the existence of a third variant of P. vivax cannot be confirmed in the geographic areas studied.

Asunto(s)

ADN Protozoario/sangre , Malaria Vivax/parasitología , Plasmodium vivax/aislamiento & purificación , África/epidemiología , Animales , Asia/epidemiología , Secuencia de Bases , Southern Blotting , América Central/epidemiología , Sondas de ADN , Genes Protozoarios , Humanos , Malaria Vivax/epidemiología , Datos de Secuencia Molecular , Plasmodium vivax/genética , Proteínas Protozoarias/genética , Sensibilidad y Especificidad , América del Sur/epidemiología , Especificidad de la Especie

RESUMEN

The presence in the New World of a variant strain of Plasmodium vivax (VK247) containing a unique circumsporozoite (CS) repeat domain was determined by the detection of antibodies to the variant CS protein and by genetic analysis of the CS gene from field isolates. Whole blood specimens were collected on filter paper from patients infected with P. vivax in Mexico and Peru. Plasmodium vivax DNA was eluted from filter paper samples and the CS gene was amplified by the polymerase chain reaction (PCR) and analyzed for the presence of VK247 or VK210 DNA by oligoprobe hybridization. Sera eluted from a companion filter paper sample were screened for antibodies reactive with the predominant and variant repeat peptides by enzyme-linked immunosorbent assays (ELISA) and with sporozoites by the immunofluorescent antibody (IFA) test. All 24 patients were positive by PCR and oligoprobe hybridization for either VK210 (16 of 24), VK247 (3 of 24), or both (5 of 24). Mixed infections were common (5 of 7) in Peru, but were not observed in the Mexican isolates (0 of 17). All three VK247 infections from Mexico occurred in residents of the foothills above Tapachula (P = 0.02). Of patients with smear-positive P. vivax infection, 42% (10 of 24) had detectable antibodies eluted from dried blood dots that were reactive with the CS protein by IFA or ELISA. These findings establish the widespread distribution of the P. vivax variant CS protein in the New World and indicate that dried blood filter paper samples represent a valuable source of material for the serologic and molecular analysis of plasmodial infections.

Asunto(s)

Anticuerpos Antiprotozoarios/biosíntesis , Antígenos de Protozoos/genética , Variación Genética , Malaria Vivax/parasitología , Plasmodium vivax/inmunología , Proteínas Protozoarias , Animales , Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos/inmunología , Secuencia de Bases , ADN Protozoario/análisis , ADN Protozoario/química , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente , Amplificación de Genes , Humanos , México , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Sondas de Oligonucleótidos/química , Perú , Plasmodium vivax/genética , Reacción en Cadena de la Polimerasa

RESUMEN

The global distribution of a newly described variant of the Plasmodium vivax circumsporozoite (CS) gene was determined by genetic analysis of wild isolates. Whole blood specimens were collected on filter paper from patients infected with P. vivax in South America. West Africa, and the Indian subcontinent. P. vivax DNA was released from the filter paper samples, and the CS gene was amplified by polymerase chain reaction and analyzed for genetic variation. Amplified DNA was probed with oligonucleotide probes that hybridize with the predominant CS repeat region (PV210) and the variant CS repeat region (PV247) of P. vivax. The PV247 variant was found in all three geographically diverse areas. In addition, five of six consecutive patients studied had simultaneous infection with both the predominant and variant forms of P. vivax. These findings suggest that a single-epitope vaccine based on the predominant CS domain is unlikely to be protective on even a regional basis.

Asunto(s)

Antígenos de Protozoos/genética , Variación Genética , Malaria/parasitología , Plasmodium vivax/genética , Proteínas Protozoarias/genética , África Occidental , Animales , Secuencia de Bases , Southern Blotting , ADN Protozoario/química , Humanos , India , Datos de Secuencia Molecular , Sondas de Oligonucleótidos/química , Reacción en Cadena de la Polimerasa , América del Sur