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vivax human challenge

Mauricio Santos-Vega, Menno J Bouma, Vijay Kohli, Mercedes Pascual
BACKGROUND: The world is rapidly becoming urban with the global population living in cities projected to double by 2050. This increase in urbanization poses new challenges for the spread and control of communicable diseases such as malaria. In particular, urban environments create highly heterogeneous socio-economic and environmental conditions that can affect the transmission of vector-borne diseases dependent on human water storage and waste water management. Interestingly India, as opposed to Africa, harbors a mosquito vector, Anopheles stephensi, which thrives in the man-made environments of cities and acts as the vector for both Plasmodium vivax and Plasmodium falciparum, making the malaria problem a truly urban phenomenon...
December 2016: PLoS Neglected Tropical Diseases
Elamaran Meibalan, Matthias Marti
Understanding transmission biology at an individual level is a key component of intervention strategies that target the spread of malaria parasites from human to mosquito. Gametocytes are specialized sexual stages of the malaria parasite life cycle developed during evolution to achieve crucial steps in transmission. As sexual differentiation and transmission are tightly linked, a deeper understanding of molecular and cellular events defining this relationship is essential to combat malaria. Recent advances in the field are gradually revealing mechanisms underlying sexual commitment, gametocyte sequestration, and dynamics of transmissible stages; however, key questions on fundamental gametocyte biology still remain...
November 11, 2016: Cold Spring Harbor Perspectives in Medicine
Angel Rosas-Aguirre, Dionicia Gamboa, Paulo Manrique, Jan E Conn, Marta Moreno, Andres G Lescano, Juan F Sanchez, Hugo Rodriguez, Hermann Silva, Alejandro Llanos-Cuentas, Joseph M Vinetz
Malaria in Peru, dominated by Plasmodium vivax, remains a public health problem. The 1990s saw newly epidemic malaria emerge, primarily in the Loreto Department in the Amazon region, including areas near to Iquitos, the capital city, but sporadic malaria transmission also occurred in the 1990s-2000s in both north-coastal Peru and the gold mining regions of southeastern Peru. Although a Global Fund-supported intervention (PAMAFRO, 2005-2010) was temporally associated with a decrease of malaria transmission, from 2012 to the present, both P...
December 28, 2016: American Journal of Tropical Medicine and Hygiene
Claudia Surjadjaja, Asik Surya, J Kevin Baird
Endemic malaria occurs across much of the vast Indonesian archipelago. All five species of Plasmodium known to naturally infect humans occur here, along with 20 species of Anopheles mosquitoes confirmed as carriers of malaria. Two species of plasmodia cause the overwhelming majority and virtually equal shares of malaria infections in Indonesia: Plasmodium falciparum and Plasmodium vivax The challenge posed by P. vivax is especially steep in Indonesia because chloroquine-resistant strains predominate, along with Chesson-like strains that relapse quickly and multiple times at short intervals in almost all patients...
December 28, 2016: American Journal of Tropical Medicine and Hygiene
Yossef Alnasser, Cusi Ferradas, Taryn Clark, Maritza Calderon, Alejandro Gurbillon, Dionicia Gamboa, Uri S McKakpo, Isabella A Quakyi, Kwabena M Bosompem, David J Sullivan, Joseph M Vinetz, Robert H Gilman
Plasmodium vivax is the most prevalent cause of human malaria in the world and can lead to severe disease with high potential for relapse. Its genetic and geographic diversities make it challenging to control. P. vivax is understudied and to achieve control of malaria in endemic areas, a rapid, accurate, and simple diagnostic tool is necessary. In this pilot study, we found that a colorimetric system using AuNPs and MSP10 DNA detection in urine can provide fast, easy, and inexpensive identification of P. vivax...
October 2016: PLoS Neglected Tropical Diseases
Geraldine Bossard, Pascal Grébaut, Sophie Thévenon, Martial Séveno, David Berthier, Philippe Holzmuller
Trypanosomes are bloodstream protozoan parasites, which are pathogens of veterinary and medical importance. Several mammalian species, including humans, can be infected by different species of the genus Trypanosoma (T. congolense, T. evansi, T. brucei, T. vivax) exhibiting more or less virulent and pathogenic phenotypes. A previous screening of the excreted-secreted proteins of T. congolense demonstrated an overexpression of several proteins correlated with the virulence and pathogenicity of the strain. Of these proteins, calreticulin (CRT) has shown differential expression between two T...
September 26, 2016: Infection, Genetics and Evolution
Chester Joyner, Alberto Moreno, Esmeralda V S Meyer, Monica Cabrera-Mora, Jessica C Kissinger, John W Barnwell, Mary R Galinski
BACKGROUND: Plasmodium vivax infections in humans or in new world monkeys pose research challenges that necessitate the use of alternative model systems. Plasmodium cynomolgi is a closely related species that shares genetic and biological characteristics with P. vivax, including relapses. Here, the haematological dynamics and clinical presentation of sporozoite-initiated P. cynomolgi infections in Macaca mulatta (rhesus macaques) are evaluated over a 100-day period. METHODS: Five M...
September 2, 2016: Malaria Journal
Francis B Ntumngia, Richard Thomson-Luque, Letícia de Menezes Torres, Karthigayan Gunalan, Luzia H Carvalho, John H Adams
UNLABELLED: Erythrocyte invasion by malaria parasites is essential for blood-stage development and an important determinant of host range. In Plasmodium vivax, the interaction between the Duffy binding protein (DBP) and its cognate receptor, the Duffy antigen receptor for chemokines (DARC), on human erythrocytes is central to blood-stage infection. Contrary to this established pathway of invasion, there is growing evidence of P. vivax infections occurring in Duffy blood group-negative individuals, suggesting that the parasite might have gained an alternative pathway to infect this group of individuals...
2016: MBio
Caeul Lim, Ligia Pereira, Kathryn Shaw Saliba, Anjali Mascarenhas, Jennifer N Maki, Laura Chery, Edwin Gomes, Pradipsinh K Rathod, Manoj T Duraisingh
Plasmodium vivax, the most widely distributed human malaria parasite, is restricted to reticulocytes, limiting its asexual proliferation. In recent years, cases of severe and high-level P. vivax parasitemia have been reported, challenging the assumption that all isolates are equally restricted. In this article, we analyze the reticulocyte preference of a large number of Indian P. vivax isolates. Our results show that P. vivax isolates significantly vary in their level of reticulocyte preference. In addition, by carefully staging the parasites, we find that P...
October 1, 2016: Journal of Infectious Diseases
Quique Bassat, Mar Velarde, Ivo Mueller, Jessica Lin, Toby Leslie, Chansuda Wongsrichanalai, J Kevin Baird
There is inadequate understanding of the biology, pathology, transmission, and control of Plasmodium vivax, the geographically most widespread cause of human malaria. During the last decades, study of this species was neglected, in part due to the erroneous belief that it is intrinsically benign. In addition, many technical challenges in culturing the parasite also hampered understanding its fundamental biology and molecular and cellular responses to chemotherapeutics. Research on vivax malaria needs to be substantially expanded over the next decade to accelerate its elimination and eradication...
December 28, 2016: American Journal of Tropical Medicine and Hygiene
Rosalind E Howes, Katherine E Battle, Kamini N Mendis, David L Smith, Richard E Cibulskis, J Kevin Baird, Simon I Hay
Plasmodium vivax is the most widespread human malaria, putting 2.5 billion people at risk of infection. Its unique biological and epidemiological characteristics pose challenges to control strategies that have been principally targeted against Plasmodium falciparum Unlike P. falciparum, P. vivax infections have typically low blood-stage parasitemia with gametocytes emerging before illness manifests, and dormant liver stages causing relapses. These traits affect both its geographic distribution and transmission patterns...
December 28, 2016: American Journal of Tropical Medicine and Hygiene
Dorothy E Loy, Weimin Liu, Yingying Li, Gerald H Learn, Lindsey J Plenderleith, Sesh A Sundararaman, Paul M Sharp, Beatrice H Hahn
Plasmodium falciparum and Plasmodium vivax account for more than 95% of all human malaria infections, and thus pose a serious public health challenge. To control and potentially eliminate these pathogens, it is important to understand their origins and evolutionary history. Until recently, it was widely believed that P. falciparum had co-evolved with humans (and our ancestors) over millions of years, whilst P. vivax was assumed to have emerged in southeastern Asia following the cross-species transmission of a parasite from a macaque...
July 2, 2016: International Journal for Parasitology
Rapatbhorn Patrapuvich, Kaewta Lerdpanyangam, Rachaneeporn Jenwithisuk, Siriwan Rungin, Rachasak Boonhok, Apisak Duangmanee, Narathatai Yimamnuaychok, Jetsumon Sattabongkot
Plasmodium vivax presents a great challenge to malaria control because of the ability of its dormant form in the liver, the hypnozoite, to cause relapse in otherwise fully recovered patient. Research efforts to better understand P. vivax hypnozoite biology have been hampered by the limited availability of its sporozoite form responsible for liver infection. Thus, the ability to cryopreserve and recover P. vivax sporozoites is an essential procedure. In this study, protective effects of hydroxyethyl starch (HES) alone and in combination with other cryoprotectants on P...
March 2016: Southeast Asian Journal of Tropical Medicine and Public Health
Marcelo U Ferreira, Marcia C Castro
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...
2016: Malaria Journal
Jean Popovici, Didier Ménard
Plasmodium vivax is the most widespread human malaria parasite, but has received much less attention than Plasmodium falciparum during the past 50 years of research. Plasmodium vivax was historically seen as causing only benign disease, but this view has recently changed, with increased recognition of the burden of vivax malaria, as well as numerous case reports of severe malaria or death caused by this parasite. The complexity of P. vivax biology is characteristic of specific features of the parasite, and recent years have seen major progress in our understanding of this complexity...
December 2015: Trends in Molecular Medicine
Wanlapa Roobsoong
Plasmodium vivax is considered as the most widely distributed human malaria parasite outside Africa. Studies of P. vivax malaria have always been limited due to the lack of continuously in vitro-propagated parasite lines. Due to this limitation, studies on P. vivax have lagged behind that of P. falciparum, which is routinely maintained in in vitro blood-stage culture. This method allows for the short-term ex vivo culture of P. vivax blood stages and as such offers a wealth of opportunities to study the biology of the blood stages of the parasite...
2015: Methods in Molecular Biology
Daniel M Parker, Verena I Carrara, Sasithon Pukrittayakamee, Rose McGready, François H Nosten
BACKGROUND: Malaria in Southeast Asia frequently clusters along international borders. For example, while most of Thailand is malaria free, the border region shared with Myanmar continues to have endemic malaria. This spatial pattern is the result of complex interactions between landscape, humans, mosquito vectors, and malaria parasites. An understanding of these complex ecological and socio-cultural interactions is important for designing and implementing malaria elimination efforts in the region...
October 5, 2015: Malaria Journal
Hannah M Edwards, Sara E Canavati, Chandary Rang, Po Ly, Siv Sovannaroth, Lydie Canier, Nimol Khim, Didier Menard, Ruth A Ashton, Sylvia R Meek, Arantxa Roca-Feltrer
BACKGROUND: Human population movement across country borders presents a real challenge for malaria control and elimination efforts in Cambodia and its neighbouring countries. To quantify Plasmodium infection among the border-crossing population, including asymptomatic and artemisinin resistant (AR) parasites, three official border crossing points, one from each of Cambodia's borders with Thailand, Laos and Vietnam, were selected for sampling. METHODS AND FINDINGS: A total of 3206 participants (of 4110 approached) were recruited as they crossed the border, tested for malaria and interviewed...
2015: PloS One
Andrew A Lover, Richard J Coker
BACKGROUND: Malaria parasites within an individual infection often consist of multiple strains (clonal populations) of a single species, which have the potential to interact both with one another, and with the host immune system. Several effects of these interactions have been measured in different parasite systems including competition and mutualism; however, direct observation of these effects in human malaria has been limited by sampling complexities and inherent ethical limitations...
December 2015: Infection, Genetics and Evolution
Seleshi Kebede Mekonnen, Girmay Medhin, Nega Berhe, Ronald M Clouse, Abraham Aseffa
BACKGROUND: The development and spread of chloroquine-resistant Plasmodium falciparum threatens the health of millions of people and poses a major challenge to the control of malaria. Monitoring drug efficacy in 2-year intervals is an important tool for establishing rational anti-malarial drug policies. This study addresses the therapeutic efficacy of artemether-lumefantrine (AL) for the treatment of Plasmodium falciparum in southwestern Ethiopia. METHODS: A 28-day in vivo therapeutic efficacy study was conducted from September to December, 2011, in southwestern Ethiopia...
2015: Malaria Journal
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