Perspective on emergence and re-emergence of amantadine resistant influenza A viruses in domestic animals in China.

In China, approximately 20% of the animal original influenza A viruses have molecular markers of amantadine resistance. Through phylogenetic data analyses and geospatial statistical analyses, this study suggests emergence of amantadine resistance in animal influenza could be due to selection pressures in China, for example, amantadine usage in some areas.

Delayed Plasmodium falciparum clearance following artesunate-mefloquine combination therapy in Thailand, 1997-2007.

Background: There is concern that artesunate resistance is developing in Southeast Asia. The purpose of this study is to investigate the prevalence of parasitaemia in the few days following treatment with artesunate-mefloquine (AM), which is an indirect measure of decreased artesunate susceptibility.

Methods: This is a retrospective analysis of 31 therapeutic efficacy studies involving 1,327 patients treated with AM conducted by the Thai National Malaria Control Programme from 1997-2007.

Socio-demographic characteristics associated with HIV and syphilis seroreactivity among pregnant women in Blantyre, Malawi, 2000-2004.

Objectives: We aimed to evaluate socio-demographic factors associated with HIV and syphilis seroreactivity in pregnant Malawians presenting for antenatal care in late third trimester of pregnancy.

Methods: Between December 2000 and March 2004 at Queen Elizabeth Central Hospital Blantyre, Malawi, we collected cross-sectional clinical and socioeconomic data from consenting women. HIV-1 status was determined using rapid HIV antibody tests and syphilis seroreactivity was determined using Rapid Plasma Reagin (RPR) and confirmed with Treponema pallidum hemagglutination assay (TPHA).

Pfmdr1 copy number and arteminisin derivatives combination therapy failure in falciparum malaria in Cambodia.

Background: The combination of artesunate and mefloquine was introduced as the national first-line treatment for Plasmodium falciparum malaria in Cambodia in 2000. However, recent clinical trials performed at the Thai-Cambodian border have pointed to the declining efficacy of both artesunate-mefloquine and artemether-lumefantrine. Since pfmdr1 modulates susceptibility to mefloquine and artemisinin derivatives, the aim of this study was to assess the link between pfmdr1 copy number, in vitro susceptibility to individual drugs and treatment failure to combination therapy.

dhfr and dhps genotype and sulfadoxine-pyrimethamine treatment failure in children with falciparum malaria in the Democratic Republic of Congo.

Objective: To determine the relationship between mutations in dhfr and dhps and SP treatment failure in Plasmodium falciparum malaria in the Democratic Republic of the Congo (DRC).

Methods: Therapeutic efficacy trial was conducted in Rutshuru, Eastern DRC, between June and September 2002, comparing sulfadoxine-pyrimethamine (SP), SP plus amodiaquine (AQSP) and artesunate plus SP (ASSP) regimens for treating malaria in children under 5 years old. We genotyped 212 samples for mutations associated with SP resistance and investigated their association with treatment failure.

Molecular surveillance for multidrug-resistant Plasmodium falciparum, Cambodia.

We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004-2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate-mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective.

A randomized controlled pilot trial of azithromycin or artesunate added to sulfadoxine-pyrimethamine as treatment for malaria in pregnant women.

Objective: New anti-malarial regimens are urgently needed in sub-Saharan Africa because of the increase in drug resistance. We investigated the safety and efficacy of azithromycin or artesunate combined with sulfadoxine-pyrimethamine used for treatment of malaria in pregnant women in Blantyre, Malawi.

Methods/findings: This was a randomized open-label clinical trial, conducted at two rural health centers in Blantyre district, Malawi.

Pfmdr1 and in vivo resistance to artesunate-mefloquine in falciparum malaria on the Cambodian-Thai border.

Artemisinin combination therapies (ACTs) have recently been adopted as first-line therapy for Plasmodium falciparum infections in most malaria-endemic countries. In this study, we estimated the association between artesunate-mefloquine therapy failure and genetic changes in the putative transporter, pfmdr1. Blood samples were acquired from 80 patients enrolled in an 2004 in vivo efficacy study in Pailin, Cambodia, and genotyped for pfmdr1 copy number and haplotype.

Estimating true antimalarial efficacy by heteroduplex tracking assay in patients with complex Plasmodium falciparum infections.

Heteroduplex tracking assays (HTAs) of Plasmodium falciparum merozoite surface protein 1 block-2 were used to assess complexity of infection and treatment efficacy in a trial of three antimalarial treatments in 141 Malawian pregnant women. An elevated complexity of infection (COI) was associated with anemia, parasite burden, and human immunodeficiency virus infection but was not associated with age or gravidity. Comparisons of HTA patterns before and after treatment allowed the classification of 20 of 30 (66%) recurrent episodes as either definite treatment failures or reinfections.

Longitudinal study of aspergillosis in sea fan corals.

Aspergillosis (a fungal disease) is affecting sea fan corals Gorgonia spp. throughout the Caribbean. To measure the impact of this disease, we established longitudinal, or in other words individual-based, monitoring studies on 3 reefs in the Florida Keys, USA, to obtain estimates of incidence, rates of disease progress, recovery, and mortality.

Maternal-fetal microtransfusions and HIV-1 mother-to-child transmission in Malawi.

Background: Between 25% and 35% of infants born to HIV-infected mothers become HIV-1 infected. One potential route of mother-to-child transmission (MTCT) could be through a breakdown in the placental barrier (i.e.

Mutations associated with sulfadoxine-pyrimethamine and chlorproguanil resistance in Plasmodium falciparum isolates from Blantyre, Malawi.

We conducted a prevalence study of mutations in Plasmodium falciparum that are associated with antifolate resistance in Blantyre, Malawi. The dihydrofolate reductase 164-Leu mutation, which confers resistance to both pyrimethamine and chlorproguanil, was found in 4.7% of the samples.

Real-time PCR methods for monitoring antimalarial drug resistance.

Drug-resistant Plasmodium falciparum is a challenge to malaria control programs. Policy makers currently depend on in vivo (and, sometimes, in vitro) resistance testing to set treatment guidelines. Molecular markers such as mutations in dhfr, dhps, pfcrt and pfmdr1 represent potential surveillance tools.

Rapid real-time PCR genotyping of mutations associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum.

The resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine (SP) is an emerging public health threat. Resistance to these drugs is associated with point mutations in the genes encoding dihydropteroate synthase (DHPS) and dihydrofolate reductase (DHFR). We describe here an assay using real-time PCR and sequence-specific probes that detects these mutations.