Ebola virus disease in Africa: epidemiology and nosocomial transmission.

The 2014 Ebola outbreak in West Africa, primarily affecting Guinea, Sierra Leone, and Liberia, has exceeded all previous Ebola outbreaks in the number of cases and in international response. There have been 20 significant outbreaks of Ebola virus disease in Sub-Saharan Africa prior to the 2014 outbreak, the largest being that in Uganda in 2000, with 425 cases and a mortality of 53%. Since the first outbreaks in Sudan and Zaire in 1976, transmission within health facilities has been of major concern, affecting healthcare workers and acting as amplifiers of spread into the community. The lack of resources for infection control and personal protective equipment are the main reasons for nosocomial transmission. Local strategies to improve infection control, and a greater understanding of local community views on the disease, have helped to bring outbreaks under control. Recommendations from previous outbreaks include improved disease surveillance to enable more rapid health responses, the wider availability of personal protective equipment, and greater international preparedness.

More than just a simple abscess: could it be caused by Panton-Valentine leukocidin positive Staphylococcus aureus?

OBJECTIVE: A 33-year-old woman presented with a three-day history of an abscess in the left alar region, four weeks after drainage of a breast abscess. The later infection was confirmed to be due to Panton-Valentine leukocidin positive, methicillin-resistant Staphylococcus aureus. This report aims to raise awareness of such infections, and to advise when Panton-Valentine leukocidin toxin testing is appropriate. METHOD: Case report and discussion. RESULTS: Although superficial Panton-Valentine leukocidin positive Staphylococcus aureus infections are relatively benign, more serious infections can be potentially life-threatening. Clinicians should be able to identify the features of potential Panton-Valentine leukocidin positive Staphylococcus aureus infection, in order to implement appropriate therapy. CONCLUSION: Clinicians need to be aware of Panton-Valentine leukocidin positive Staphylococcus aureus infections, and should ask specific questions when investigating the clinical history of patients with recurrent abscesses, as this bacterial strain is not routinely assessed by microbiology departments. If such an infection is suspected, clinicians should be aware of local protocols regarding toxin testing, antibiotic choice and decolonisation agents.

Hospital-based epidemiology: a strategy for 'dealing with Clostridium difficile'.

Clostridium difficile-associated diarrhoea (CDAD) remains a major infection control problem. Uncertainty remains over methods of diagnosis and definitions for ascertaining provenance of cases. We undertook a prospective epidemiological study to better ascertain local epidemiology of 275 new cases (general practitioner and hospital) diagnosed in a large teaching hospital in the UK. The highest incidence of cases was found in haematology and critical care and a surprisingly high proportion, 29%, of hospital cases occurred in those aged <65 years. Fifty-five cases were diagnosed within 48h of admission. Of these, those defined as 'community-acquired' varied between 9 and 25 according to various proposed definitions relating to acquisition and onset of diarrhoea. Of 48 community-onset cases, this number varied between 19 and 25, the variability making comparisons between National Health Service (NHS) trusts potentially inaccurate. Cases were followed for 90 days after diagnosis and all cause mortality data obtained. Of 227 cases diagnosed in hospital, 56 (25%) died within 30 days, 29% of whom were aged <65 years. Death certification data were available in 86% of these cases. C. difficile was recorded on 15 (31%) certificates and as a primary cause (1a or 1b) in 8 (17%) cases. Our study shows the value of local epidemiology for planning infection prevention and control strategies within an NHS trust and for contributing to the evidence base for national targets and policies.

Poverty and infection in the developing world: healthcare-related infections and infection control in the tropics.

In many hospitals serving the poorest communities of Africa and other parts of the developing world, infection control activities are limited by poor infrastructure, overcrowding, inadequate hygiene and water supply, poorly functioning laboratory services and a shortage of trained staff. Hospital transmission of communicable diseases, a high prevalence of human immunodeficiency virus and multidrug-resistant tuberculosis, lack of resources for isolation and disinfection, and widespread antimicrobial resistance create major risks for healthcare-related infections. Few data exist on the prevalence or impact of these infections in such environments. There is a need for interventions to reduce the burden of healthcare-related infections in the tropics and to set up effective surveillance programmes to determine their impact. Both the Global (G8) International Development Summit of 2005 and the United Nations Millennium Development Goals (MDGs) have committed major resources to alleviating poverty and poor health in the developing world over the next decade. Targeting resources specifically to infection control in low-resource settings must be a part of this effort, if the wider aims of the MDGs to improve healthcare are to be achieved.

A survey of antimicrobial prescribing and dispensing practices in rural Bangladesh.

This study was undertaken to determine the patterns of antimicrobial prescription by 64 Rural Medical Practitioners (RMPs) from Bangladesh. The antimicrobial dispensing procedures followed by the local retail drug sellers along with the purchasing capacities of the patients was also assessed. All antimicrobial agents were prescribed mainly on the patient's complaints, and all available antibiotics were prescribed in inappropriate doses and duration. In most cases, the RMPs initiated treatment with a parenteral form of antibiotic, and a different oral antibiotic usually followed. Parenteral streptomycin was used most frequently in short inadequate courses. Almost half of the antibiotics were sold without any prescriptions, and even ordinary people without any knowledge of medicine asked the drug seller for specific antibiotics. This unregulated prescribing and dispensing practice has the potential risk for the development and spread of antimicrobial resistance on a global scale.

Long-term dynamics of Ligula intestinalis and roach Rutilus rutilus: a study of three epizootic cycles over thirty-one years.

Data are presented on 2 full epizootic cycles and the start of a third of Ligula intestinalis in roach Rutilus rutilus in a small lake, and the relationships of these cycles to the densities of rudd, Scardinius erythrophthalmus, and Great Crested Grebes, Podiceps cristatus, over 31 years. The parasite was introduced to the lake by P. cristatus in 1973 at a time when the roach population had increased in response to eutrophication to a level at which individual fish growth was stunted and the hithero dominant rudd population had declined in numbers as a consequence of inter-specific competition with roach. Ligula prevalence peaked at 28% in only 2 years: thereafter parasite-induced host mortality caused a decline in the roach population, releasing fish from stunting and allowing the rudd population to recover. The consequent improved growth of roach individuals and their short life-span reduced Ligula transmission rates and prevalence levels declined to approximately 1% although Ligula nevertheless persisted for a further 10 years. Following a massive winter-kill of the fish populations in 1984-1985, fish and Ligula numbers declined to barely detectable levels and the parasite disappeared from samples. Rudd recovered first, then roach and interspecific competition again led to a decline in rudd numbers. This increase in roach numbers led to a decrease in roach growth rates, which coincided with the re-colonization of the lake by Ligula. This second epizootic of Ligula peaked within 2 years in 1991-1992, when up to 78% of roach were infected with a maximum abundance of 2.2 parasites and intensity of 21 parasites. Heavy parasite-induced mortality of roach led to a decline in numbers, an improvement in individual growth rate and a reduction of Ligula transmission rates such that the epizootic died out in 1996. Similar conditions of roach numbers and growth prevailed at the start of a third cycle in 1998. The course of events over the second cycle was so similar to that of the first that it confirms the interpretations of that cycle. Comparison with other localities shows that epizootics of Ligula always coincide with rapid increases in roach numbers, for whatever cause, and stunted growth, which together attract piscivorous birds. At the start of a cycle Ligula is a major determinant of the population dynamics of the roach, but at the end of the cycle the fish population dynamics determine those of the parasite. The cycles are not regulated and the roach-Ligula system is inherently unstable.

Antibiotic resistance in the tropics. Epidemiology and surveillance of antimicrobial resistance in the tropics.

Antimicrobial resistance is threatening to undermine many of the health care improvements achieved in the tropics in the past 2 decades. While only limited data are available, there is evidence from most tropical areas of the spread of resistant bacterial strains in diseases from typhoid and bacillary dysentery to tuberculosis and, as in industrialized countries, multiply resistant hospital pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Attempts to control the spread of resistant bacteria are limited by the lack of surveillance data at both the local and international level. For effective surveillance programmes to be implemented, the strengthening of laboratory services at district and national level, with a long-term commitment to resources, training and quality control, is essential.

Recent developments in cholera.

Cholera continues to be an important public health problem among many poorer communities in Africa, Asia and South America, despite the bacteriology and epidemiology of the disease having been described over a century ago. Molecular techniques have enabled current researchers to gain new insights into pathogenicity, into the relationships between environmental and clinical strains, and into new strategies for vaccine development. The description of non-culturable 'dormant' strains in the environment and the effect of environmental factors on toxin gene regulation provide valuable clues to the ecology of the disease. Disease management continues to be based on urgent and appropriate rehydration, and recent community studies emphasize the need for effective local health services to provide this if case fatality rates are to remain low. While antimicrobial agents may play a role in case management and prophylaxis, the increasing prevalence of antimicrobial resistance must be addressed. New vaccine candidates, based on a molecular understanding of pathogenicity, provide scope for improved strategies for disease prevention, though the appropriate public health context for their use has not been determined. This review summarizes activities in these fields of cholera research and considers the continuing global problem of the disease.

Performance characteristics of the polymerase chain reaction assay to confirm clinical meningococcal disease.

BACKGROUND: Confirmation of clinical meningococcal disease (MCD) is essential for management of patients, contacts, and outbreaks. Blood and CSF cultures, the traditional gold standard diagnostic tests, have been adversely affected by preadmission parenteral penicillin and fewer lumbar punctures. Rapid, reliable serogroup determination without the need to grow isolates could improve laboratory confirmation of MCD. AIMS: To determine performance characteristics of the currently available meningococcal polymerase chain reaction (PCR) assays in a clinical setting. METHODS: Prospective study of 319 children presenting with a suspected diagnosis of MCD (fever and a rash, or suspected bacterial meningitis) over a 16 month period. RESULTS: A total of 166 (52% of all) children had clinical MCD: diagnosis was confirmed microbiologically in 119 (72%) of these. Performance characteristics (sensitivity, specificity, negative predictive value, positive predictive value) in confirmation of clinical MCD were respectively (95% confidence interval): blood culture 31% (24-38%), 100%, 57% (49-65%), 100%; blood PCR 47% (39-55%), 100%, 65% (58-73%), 100%; any test positive 72% (65-79%), 100%, 77% (70-84%), 100%. CONCLUSIONS: Meningococcal DNA detection in blood or CSF by PCR is a useful method of diagnosis of MCD. PCR of peripheral blood performs better than blood culture. In a child with clinically suspected MCD, PCR assays, bacterial antigen tests, and oropharyngeal swabbing for meningococcal carriage should be performed in addition to blood or CSF culture, to improve case confirmation.

Communicable disease surveillance with limited resources: the scope to link human and veterinary programmes.

Zoonoses are an important cause of human disease in much of Africa, but limitations in current diagnosis and surveillance strategies restrict the effectiveness of control and prevention programmes. Outbreaks of disease, ranging from Ebola virus infection to Rift Valley Fever, that have occurred recently in Africa have demonstrated the need for improved disease surveillance and monitoring. Strategies are suggested for co-ordinating human and animal disease surveillance programmes, at the district and regional level, to make more effective use of limited resources.

Antimicrobial resistance in the tropics.

Bacterial resistance to antimicrobial agents is an increasing problem in many areas of the tropics. In most countries there is little information available to determine the patterns of resistance in different pathogens, nor are local data available to influence prescribing. This paper will review the development of antimicrobial resistance in the tropics, consider the current priority problems, and suggest strategies that may be taken to improve the surveillance of resistance.

Emerging and reemerging infections in africa: the need for improved laboratory services and disease surveillance.

Emerging and reemerging infections pose a serious public health threat to most countries of tropical Africa. In the past decade, epidemics of diseases including cholera, dysentery, meningitis, yellow fever and Ebola virus have resulted in significant morbidity and mortality. Improved laboratory services and disease surveillance systems are essential to monitor disease trends and to initiate public health action. The present situation of emerging and reemerging infections in Africa is described in this review, and strategies for improved disease surveillance and monitoring are discussed.

Increasing microbiological confirmation and changing epidemiology of meningococcal disease on Merseyside, England.

OBJECTIVES: To determine, for the last 5 years in children on Merseyside with clinical meningococcal disease (MCD), the impact on diagnostic yield of newer bacteriologic methods; bacterial antigen detection (AD) and polymerase chain reaction (PCR). METHODS: Prospective data collection at Royal Liverpool Children's Hospital over two epochs: 1 September 1992 to 30 April 1994 (epoch A, n = 126) and 17 November 1997 to 15 September 1998 (epoch B, n = 85). RESULTS: Epoch A was compared with epoch B. Diagnosis was confirmed by detection of meningococci in 78 of 126 (61.9%) versus 64 of 85 (75.3%, P = 0.04), but with a significantly lower rate of positive blood and cerebrospinal fluid culture in the later epoch. The proportion of cases receiving penicillin pretreatment was unchanged at 32%, but the proportion undergoing lumbar puncture decreased significantly. Median ages were higher in epoch B: 1.7 years versus 2.49 years (P = 0.013, Mann-Whitney). There was a significant increase in the proportion of cases due to serogroup C (14/78 (18%) versus 30/64 (46.9%), P = 0.001). CONCLUSIONS: Culture detection of meningococci from children with MCD has reduced, as less lumbar punctures are done. However, improved diagnosis by PCR and AD has increased microbiological confirmation overall. Serogroup C disease and the median age of cases continue to rise.

Water quality and public health in northern Sudan: a study of rural and peri-urban communities.

Access to adequate supplies of good quality drinking water continues to be limited among many rural and peri-urban communities in Africa, despite several decades of water improvement programmes. The present study investigated water quality at the source and point of consumption among rural and peri-urban communities in northern Sudan. Faecal coliform counts were determined by the membrane filtration technique and geometric mean counts compared in different seasons and among the different communities. Among nomadic pastoralists and riverine villages, both water sources and water stored for consumption had faecal coliform counts grossly in excess of WHO standards, with higher counts at the end of the rainy season. In the peri-urban community on the outskirts of Omdurman, while water quality from the distribution system had faecal coliform counts generally below 10 dl - 1, after storage, water was of considerably lower quality, with faecal coliform counts up to 1000 d1 - 1. The highest counts again occurred in the rainy season. Rates of diarrhoeal disease for Khartoum province were also greatest towards the end of the rainy season. The study has shown that poor quality water continues to be a major risk factor for public health in these communities.