Herpes simplex virus and HIV-1: deciphering viral synergy

Recent proof-of-concept randomised controlled trials have shown a causal relation between herpes simplex virus (HSV) type 2 infection and HIV-1 replication in co-infected individuals. We explore the mechanisms that may operate to enhance reciprocal viral replication. Direct interactions could involve HIV-1-related immune deficiency, disruption of mucosal barrier by HSV infection/reactivation, HSV-induced mucosal cell recruitment, transactivation of HIV-1 replication by HSV proteins, and immune modulation by HSV decoys. Indirect interactions might coexist through disturbances of the vaginal flora during HSV shedding and systemic immune activation. In co-infected individuals, suppressive HSV treatment reduces HIV-1 genital and systemic excretion. This finding is a likely result of efficacious prevention of HSV2 reactivations, and perhaps of other herpesviruses. Strategies to control HSV2 and other herpesviruses deserve urgent attention and should become part of the HIV-1 prevention and care package.     

Patterns of a Sylvatic Yellow Fever Virus Amplification in Southeastern Senegal, 2010

During the wet season of 2010, yellow fever virus (YFV) was detected in field-collected mosquitoes in the Kédougou region in southeastern Senegal. During this outbreak, we studied the association of the abundance of YFV-infected mosquitoes and land cover features to try and understand the dynamics of YFV transmission within the region. In total, 41,234 mosquito females were collected and tested for virus infection in 5,152 pools. YFV was detected in 67 pools; species including Aedes furcifer (52.2% of the infected pools), Ae. luteocephalus (31.3% of the infected pools), Ae. taylori (6.0% of the infected pools) and six other species (10.4% of the infected pools) captured in September (13.4%), October (70.1%), and November (16.4%). Spatially, YFV was detected from mosquitoes collected in all land cover classes but mainly, forest canopies (49.2%). Human infection is likely mediated by Ae. furcifer, the only species found infected with YFV within villages. Villages containing YFV-infected mosquitoes were significantly closer to large forests (> 2 ha) than villages in which no infected mosquitoes were detected.     

Repeated artemisinin-based combination therapies in a malaria hyperendemic area of Mali: efficacy, safety, and public health impact

Artemisinin-based combination therapies (ACTs) are the first-line treatment of uncomplicated malaria. The public health benefit and safety of repeated administration of a given ACT are poorly studied. We conducted a randomized trial comparing artemether-lumefantrine, artesunate plus amodiaquine (AS+AQ) and artesunate plus sulfadoxine-pyrimethamine (AS+SP) in patients 6 months of age and older with uncomplicated malaria in Mali from July 2005 to July 2007. The patient received the same initial treatment of each subsequent uncomplicated malaria episode except for treatment failures where quinine was used. Overall, 780 patients were included. Patients in the AS+AQ and AS+SP arms had significantly less risk of having malaria episodes; risk ratio (RR) = 0.84 (P = 0.002) and RR = 0.80 (P = 0.001), respectively. The treatment efficacy was similar and above 95% in all arms. Although all drugs were highly efficacious and well tolerated, AS+AQ and AS+SP were associated with less episodes of malaria.     

Origin and Spread of the Dengue Virus Type 1, Genotype V in Senegal, 2015–2019

Dengue virus (DENV) is the most widespread arthropod-borne virus, with the number and severity of outbreaks increasing worldwide in recent decades. Dengue is caused by genetically distinct serotypes, DENV-1–4. Here, we present data on DENV-1, isolated from patients with dengue fever during an outbreak in Senegal and Mali (Western Africa) in 2015–2019, that were analyzed by sequencing the envelope (E) gene. The emergence and the dynamics of DENV-1 in Western Africa were inferred by using maximum likelihood and Bayesian methods. The DENV-1 grouped into a monophyletic cluster that was closely related to those from Southeast Asia. The virus appears to have been introduced directly into Medina Gounass (Suburb of Dakar), Senegal (location probability = 0.301, posterior = 0.76). The introduction of the virus in Senegal occurred around 2014 (95% HPD = 2012.88–2014.84), and subsequently, the virus moved to regions within Senegal (e.g., Louga and Fatick), causing intense outbreaks in the subsequent years. The virus appears to have been introduced in Mali (a neighboring country) after its introduction in Senegal. In conclusion, we present evidence that the outbreak caused by DENV-1 in urban environments in Senegal and Mali after 2015 was caused by a single viral introduction from Asia.     

Reduced levels of T-cell subsets CD4+ and CD8+ in homozygous sickle cell anaemia patients with splenic defects

T-lymphocyte subsets were studied in two patient groups: (1) 50 patients with homozygous sickle cell anaemia (SCA) (mean age 12 (range 3-32) years old) in good health at the time of the study who showed no infectious complication. (2) 50 patients (mean age 13 (range 4-29) years old) with normal haemoglobin rate. The global response revealed a significant increase in levels of CD3+ (P=0.04) and CD8+ (P=0.04) cells when compared with the control group, there was no significant difference in levels of CD4+ cells (P=0.05) between the two groups. However, there was a relationship between T-cell subpopulation levels and spleen status. The average values of T-cell subsets (CD4+ and CD8+) in patients with SCA-induced splenic defects (asplenic, splenomegaly or splenectomized patients) were significantly reduced when compared to SCA patients with normal spleens and the control groups. These data show that T-cell activity was reduced in patients with splenic defects. A correlation between splenic status and a perturbed host defence system in patients with SCA suggests that monitoring T-cell subsets might have prognostic value in the course of sickle cell disease.     

Rift Valley Fever Outbreak,Southern Mauritania, 2012

After a period of heavy rainfall, an outbreak of Rift Valley fever occurred in southern Mauritania during September–November 2012. A total of 41 human cases were confirmed, including 13 deaths, and 12 Rift Valley fever virus strains were isolated. Moudjeria and Temchecket Departments were the most affected areas.     

The impact of introducing new vaccines on the health system: Case studies from six low- and middle-income countries

Objective

We aimed to explore the impacts of new vaccine introductions on immunization programmes and health systems in low- and middle-income countries.

Methods

We conducted case studies of seven vaccine introductions in six countries (Cameroon, PCV; Ethiopia, PCV; Guatemala, rotavirus; Kenya, PCV; Mali, Meningitis A; Mali, PCV; Rwanda, HPV). Interviews were conducted with 261 national, regional and district key informants and questionnaires were completed with staff from 196 health facilities. Routine data from districts and health facilities were gathered on vaccination and antenatal service use. Data collection and analysis were structured around the World Health Organisation health system building blocks.

Findings

The new vaccines were viewed positively and seemed to integrate well into existing health systems. The introductions were found to have had no impact on many elements within the building blocks framework. Despite many key informants and facility respondents perceiving that the new vaccine introductions had increased coverage of other vaccines, the routine data showed no change. Positive effects perceived included enhanced credibility of the immunisation programme and strengthened health workers’ skills through training. Negative effects reported included an increase in workload and stock outs of the new vaccine, which created a perception in the community that all vaccines were out of stock in a facility. Most effects were found within the vaccination programmes; very few were reported on the broader health systems. Effects were primarily reported to be temporary, around the time of introduction only.

Conclusion

Although the new vaccine introductions were viewed as intrinsically positive, on the whole there was no evidence that they had any major impact, positive or negative, on the broader health systems.