Hepatitis C Virus Infection May Lead to Slower Emergence of P. falciparum in Blood

International audienceBACKGROUND: Areas endemic for Plasmodium falciparum, hepatitis B virus (HBV) and hepatitis C virus (HCV) overlap in many parts of sub-Saharan Africa. HBV and HCV infections develop in the liver, where takes place the first development stage of P. falciparum before its further spread in blood. The complex mechanisms involved in the development of hepatitis may potentially influence the development of the liver stage of malaria parasites. Understanding the molecular mechanisms of these interactions could provide new pathophysiological insights for treatment strategies in Malaria. METHODOLOGY: We studied a cohort of 319 individuals living in a village where the three infections are prevalent. The patients were initially given a curative antimalarial treatment and were then monitored for the emergence of asexual P. falciparum forms in blood, fortnightly for one year, by microscopy and polymerase chain reaction. PRINCIPAL FINDINGS: At inclusion, 65 (20.4%) subjects had detectable malaria parasites in blood, 36 (11.3%) were HBV chronic carriers, and 61 (18.9%) were HCV chronic carriers. During follow-up, asexual P. falciparum forms were detected in the blood of 203 patients. The median time to P. falciparum emergence in blood was respectively 140 and 120 days in HBV- and HBV+ individuals, and 135 and 224 days in HCV- and HCV+ individuals. HCV carriage was associated with delayed emergence of asexual P. falciparum forms in blood relative to patients without HCV infection. CONCLUSIONS: This pilot study represents first tentative evidence of a potential epidemiological interaction between HBV, HCV and P. falciparum infections. Age is an important confounding factor in this setting however multivariate analysis points to an interaction between P. falciparum and HCV at the hepatic level with a slower emergence of P. falciparum in HCV chronic carriers. More in depth analysis are necessary to unravel the basis of hepatic interactions between these two pathogens, which could help in identifying new therapeutic approaches against malaria

Emerging viral threats in Gabon: health capacities and response to the risk of emerging zoonotic diseases in Central Africa

Emerging infectious diseases (EID) are currently the major threat to public health worldwide and most EID events have involved zoonotic infectious agents. Central Africa in general and Gabon in particular are privileged areas for the emergence of zoonotic EIDs. Indeed, human incursions in Gabonese forests for exploitation purposes lead to intensified contacts between humans and wildlife thus generating an increased risk of emergence of zoonotic diseases. In Gabon, 51 endemic or potential endemic viral infectious diseases have been reported. Among them, 22 are of zoonotic origin and involve 12 families of viruses. The most notorious are dengue, yellow fever, ebola, marburg, Rift Valley fever and chikungunya viruses. Potential EID due to wildlife in Gabon are thereby plentiful and need to be inventoried. The Gabonese Public Health system covers geographically most of the country allowing a good access to sanitary information and efficient monitoring of emerging diseases. However, access to treatment and prevention is better in urban areas where medical structures are more developed and financial means are concentrated even though the population is equally distributed between urban and rural areas. In spite of this, Gabon could be a good field for investigating the emergence or re-emergence of zoonotic EID. Indeed Gabonese health research structures such as CIRMF, advantageously located, offer high quality researchers and facilities that study pathogens and wildlife ecology, aiming toward a better understanding of the contact and transmission mechanisms of new pathogens from wildlife to human, the emergence of zoonotic EID and the breaking of species barriers by pathogens

High prevalence of hepatitis C virus infection and predominance of genotype 4 in rural Gabon.

Hepatitis C (HCV) molecular epidemiology is documented poorly in central African countries. In response to this, a population-based study of 319 consenting adults resident in a remote village of Gabon was undertaken (mean age: 38 years; age range: 13-85+; sex ratio: 0.74). Screening for anti-HCV antibodies was performed using ELISA and recombinant immunoblot assay. Seropositive samples were assessed further with viral load and genotyping techniques. Sixty-six (20.7%) individuals were HCV seropositive. Viral loads ranged from 600 to 24.9 million IU/ml (median: 372,500). Seroprevalence and viral loads increased significantly with age (P < 10(-5) and P < 0.003, respectively). HCV sequences of the 5'UTR genome region were obtained from 60 (90.9%) samples and NS5B region sequences were obtained from 22 (36.6%) samples. All strains belonged to subtypes of genotype 4: 4e (72.7%), 4c (13.6%), 4p (4.5%), 4r (4.5%) and one unclassified genotype 4 strain. Evolutionary analysis of the subtype 4e sequences indicates a period of raised transmission during the early twentieth century

The epidemic dynamics of hepatitis C virus subtypes 4a and 4d in Saudi Arabia

The relatedness between viral variants sampled at different locations through time can provide information pertinent to public health that cannot readily be obtained through standard surveillance methods. Here, we use virus genetic data to identify the transmission dynamics that drive the hepatitis C virus subtypes 4a (HCV4a) and 4d (HCV4d) epidemics in Saudi Arabia. We use a comprehensive dataset of newly generated and publicly available sequence data to infer the HCV4a and HCV4d evolutionary histories in a Bayesian statistical framework. We also introduce a novel analytical method for an objective assessment of the migration intensity between locations. We find that international host mobility patterns dominate over within country spread in shaping the Saudi Arabia HCV4a epidemic, while this may be different for the HCV4d epidemic. This indicates that the subtypes 4a and 4d burden can be most effectively reduced by combining the prioritized screening and treatment of Egyptian immigrants with domestic prevention campaigns. Our results highlight that the joint investigation of evolutionary and epidemiological processes can provide valuable public health information, even in the absence of extensive metadata information