Bats prove fruitful for Marburg

Bats have long been suspected to be the natural reservoirs of filoviruses such as Ebola and Marburg viruses, which both cause haemorrhagic fevers with extremely high mortality rates. Although there is plenty of circumstantial evidence to support this theory, including the detection of virus RNA and virus-specific antibodies in bats, live virus had not been isolated. Towner et al. now report the results of a detailed investigation into a 2007 outbreak of Marburg haemorrhagic fever in a small group of miners who had been working in Kitaka cave in western Uganda, which contained large numbers of Egyptian fruit bats (Rousettus aegyptiacus). The authors were able to isolate live Marburg virus from five healthy bats, four that had been caught in 2007 and one that was caught eight months later, suggesting that bats can harbour the virus for a considerable period of time. Towner et al. estimate that the R. aegyptiacus colony in Kitaka cave comprises >110,000 bats and that at least 5,000 of them could be carrying Marburg virus. This study identifies the Egyptian fruit bat as a major natural reservoir for Marburg virus. PLoS Pathog.

Beginning of the end for artemisinin?

Plasmodium falciparum is becoming resistant to artemisinin in western Cambodia, according to a new report in the New England Journal of Medicine. The WHO recommends artemisinin-based therapies as a first-line treatment for uncomplicated P. falciparum malaria in endemic areas. Concern had been raised recently that the effectiveness of artemisinin-based therapies in the border area between Cambodia and Thailand was beginning to decline. Dondorp et al. carried out two open-label, randomized trials in Cambodia and Thailand to compare the efficacies of two artemisinin-based treatment regimes, an artesunate monotherapy and an artesunate and mefloquine combination therapy. They found that P. falciparum from western Cambodia has lower in vivo susceptibility to artenusate monotherapy than P. falciparum from Thailand. This is the first clinical evidence of artemisinin resistance, and the authors conclude that “Containment measures are urgently needed.” N. Engl. J. Med.

Go with the flow

For vector-borne pathogens, many different factors can influence the patterns of contact between vector and host, and identifying the key points of contact might be crucial for the development and most effective deployment of therapeutic interventions. Reporting in a recent issue of PLoS Neglected Tropical Diseases, Steven Stoddard and colleagues examined the role of human movement in the transmission of vector-borne pathogens using the mosquito-borne dengue virus in Iquitos, Peru, as an example. By constructing a conceptual activity–space model that quantifies the impact of human movement on the risk of coming into contact with infected mosquitoes, the authors were able to identify individual movement patterns that had a large impact on the dynamics of dengue transmission. This work identifies human movement as an important contributing factor to the transmission of vector-borne diseases, and one that warrants further study. PLoS Negl. Trop. Dis.

Gorillas source of HIV?

The HIV-1 virus that is the causative agent of the human AIDS pandemic first crossed into humans from chimpanzees around 100 years ago. In the wild, more than 40 simian immunodeficiency viruses (SIVs) have been identified in African primates, including the immediate ancestor of HIV-1, SIVcpz, in chimpanzees and SIVgor in Western Lowland Gorillas. Jean-Christophe Plantier and colleagues now report on the identification of a new HIV-1 virus. The virus was identified in a 62-year-old Cameroonian woman living in Paris, during routine surveillance of HIV-1 genetic diversity. Researchers had difficulty identifying the virus using commercially available assays, and genome sequencing revealed that this virus, which is most closely related to SIVgor, does not fit within the three main phylogenetic groups of HIV-1 (groups M, N and O). The authors propose that it is the prototype member of a new group of HIV-1, group P, and that the most likely explanation for its emergence is gorilla-to-human transmission of SIVgor, although transmission from chimpanzees to gorillas to humans cannot be ruled out. In a separate paper in a recent issue of Nature, Beatrice Hahn and co-workers report on the first evidence that SIVcpz infection can cause AIDS-like immunopathology in chimpanzees in the wild. Nature Med./Nature

Influenza A (H1N1) update

Pandemic influenza A (H1N1), or swine flu, continued to hit the headlines throughout July, in the United Kingdom in particular, where a national pandemic flu service was launched to ease the burden on family physicians. Individuals no longer need to see a doctor to receive Tamiflu; those who suspect they may have swine flu can check their symptoms online or by using a telephone hotline and will then receive a unique identification number that will allow a 'flu friend' to collect the antivirals from a designated collection point. By the end of the month, the United Kingdom's Chief Medical Officer, Dr Liam Donaldson, was quoted as saying that he believed the pandemic may have peaked for the time being but would return in the autumn. The majority of infected individuals continue to have only a mild illness, but concern was raised in the general media for pregnant women, who are at higher risk of complications. The status of a pandemic H1N1 vaccine also grabbed the headlines as clinical trials began in the United States and Australia; the vaccine is expected to be available by the autumn. WHO/BBC

In the News was compiled with the assistance of David Ojcius, University of California, Merced, USA. David's links to infectious disease news stories can be accessed on Connotea ( http://www.connotea.org ), under the username NatureRevMicrobiol.