Papua and New Guinea medical journal最新文献

Between 1967 and 1985 research on pneumonia in Papua New Guinea (PNG) was fundamental not only to standard treatments of disease in PNG, but also to the establishment of the World Health Organization's global Program for Control of Acute Respiratory Infections. Pneumonia was the leading cause of death in both population-based and hospital studies. Research that began in 1967 revealed a pattern of disease in adults reminiscent of that seen in industrialized countries in the early 20th century. Streptococcus pneumoniae (pneumococcus) was the predominant causative organism. Pneumococci were commensals of the upper respiratory tract that invaded first the lungs and then the blood stream. Some serotypes were more invasive than others and case fatality increased with deeper levels of invasion. The pandemic of Hong Kong (H3N2) influenza spread to the Southern Highlands in 1969 resulting in 2000 deaths. The conclusion that pneumococcal pneumonia had been the principal cause of death led to the establishment of a pneumonia research unit in Tari. A field trial of pneumococcal polysaccharide vaccine showed the vaccine to be most effective in preventing invasive disease. Vaccination reduced pneumonia mortality by 44% in previously healthy adults. The epidemiological situation was more complex in children than in adults because many different species and serotypes of bacteria could be isolated from lung aspirate. Although many of these organisms would normally have been regarded as non-pathogenic, S. pneumoniae and Haemophilus influenzae, recognized pathogens, were the principal causes of severe morbidity and mortality. The same principles of carriage of and invasion by upper respiratory commensals applied as much to children as they did to adults, and the rank order of invasive serotypes of S. pneumoniae and H. influenzae was the same in different age groups. Slow maturation of a child's immune system meant, however, that children could be susceptible to invasion by particular serotypes. Infants were frequently colonized by pathogenic bacteria within days of birth. Nasal discharge, which was extremely common, was most probably a result of domestic smoke pollution and low standards of hygiene. Aspiration of infected secretions was a likely explanation for the variety of organisms isolated from lung aspirate. A trial of pneumococcal polysaccharide vaccine showed the vaccine to be effective in preventing death from pneumonia in children 6-9 months of age provided pneumonia was not associated with other causes of death; this result was shown to be consistent with the principles of infection and invasion described above. Principles of antibiotic therapy for child pneumonia were also established at this time.

Respiratory infections are a major health burden for the people of Papua New Guinea (PNG) who are positive for human immunodeficiency virus (HIV). In the face of an ongoing HIV epidemic, little is known about the epidemiology and aetiology of respiratory infections in people living with HIV in PNG. In this article we provide an overview of the most important respiratory pathogens in HIV-positive people globally, focusing primarily on adults. Particular attention is given to respiratory viruses, bacterial pathogens such as Streptococcus pneumoniae and Mycobacterium tuberculosis, and Pneumocystis jiroveci. In doing so we highlight the need for a better understanding of the aetiology of respiratory infections in HIV-positive people in PNG. A study is underway that aims to determine the aetiology of common infectious illnesses in HIV-positive people in PNG, focusing on respiratory infections, diarrhoeal diseases and febrile illness. The results of this study should guide future prevention, diagnostic and treatment strategies.

Melioidosis is being increasingly recognized as an important cause of severe, acute community-acquired pneumonia in various tropical regions. The chronic form of melioidosis can also mimic tuberculosis. Studies have established that, while uncommon in the Port Moresby region, melioidosis is an important cause of pneumonia and sepsis in the Balimo region of Western Province. Phylogenetic analyses of strains of Burkholderia pseudomallei from Papua New Guinea have shown them to be more closely related to strains of B. pseudomallei from Australia than to strains from Southeast Asia. This is consistent with the proposed origins of B. pseudomallei in Australia, with subsequent spread out of Australia to Southeast Asia during the last ice age. Further surveillance across Papua New Guinea is likely to unmask other locations where B. pseudomallei occurs in the environment and where melioidosis is currently not being diagnosed.

A collaborative program between the Papua New Guinea (PNG) Institute of Medical Research and the Hunter Mucosal Group has completed studies relevant to protection of the airways against bacterial infection. Specifically, these studies addressed the mucosal capacity to produce local immunoglobulins and the capacity of the airways to respond to an oral vaccine containing inactivated nontypeable Haemophilus influenzae (NTHi). The mucosal IgA response to NTHi antigens was blunted in both children and adults in PNG compared with that found in Australian children and adults, whose airways are colonized only intermittently. Despite this, when oral NTHi is given to Papua New Guinean adults with chronic airways disease, it is followed by a significant (50%) reduction in incidence of acute bronchitic episodes, and a 3-log reduction in density of colonization, which persisted about 10 months. The implications of these key findings are discussed with respect to both mechanism and wider control of pathology emanating from abnormal airways colonization in a PNG environment.

Indigenous children in Australia and children in Papua New Guinea (PNG) share a high burden of respiratory disease. In PNG the focus has been on pneumonia as a major cause of mortality. While pneumonia incidence remains high in Australian Indigenous children, improved access to better health care has resulted in reduced mortality. However, severe and recurrent pneumonia are risk factors for chronic suppurative lung disease or bronchiectasis in Australian Indigenous children. Bronchiectasis is associated with significant morbidity, and early death in adulthood. This paper includes an outline of the disease manifestations of acute and chronic lower respiratory infections. The main bacterial pathogens involved in pneumonia, bronchiolitis, bronchitis and bronchiectasis have been determined. Capsular organisms such as Streptococcus pneumoniae and Haemophilus influenzae type b are more often implicated in acute infections, while chronic infections are frequently associated with nontypeable (noncapsular) H. influenzae. Moraxella catarrhalis is more often isolated from very young children. Possible reasons for the high burden of respiratory disease in Papua New Guinean children and Australian Indigenous (primarily Aboriginal) children include early and dense colonization with multiple species and strains of respiratory pathogens. There is a role for vaccines in preventing lower respiratory infection.

Nontypeable Haemophilus influenzae (NTHi) is a common microbe frequently isolated from the nasopharynx of children. Bacterial pneumonia is a major cause of morbidity and mortality in children less than 5 years of age, with the burden of disease being greatest in developing countries. Determination of the bacterial aetiology of pneumonia is difficult due to sampling constraints. However, with a combination of sampling approaches, trans-thoracic fine-needle aspiration, blood culture and screened sputum, the evidence strongly suggests that NTHi is a significant causative pathogen of pneumonia in young children. However, further studies are required. The development of a new pneumococcal conjugate vaccine containing H. influenzae protein D has the potential to be beneficial against disease caused by NTHi, including pneumonia. With the implementation of this vaccine in many regions of the world where NTHi disease is endemic, it will be critical to introduce surveillance programs wherever it is used.

Oxygen therapy is essential in all wards, emergency departments and operating theatres of hospitals at all levels, and oxygen is life-saving. In Papua New Guinea (PNG), an effective oxygen system that improved the detection and treatment of hypoxaemia in provincial and district hospitals reduced death rates from pneumonia in children by as much as 35%. The methods for providing oxygen in PNG are reviewed. A busy provincial hospital will use on average about 38,000 l of oxygen each day. Over 2 years the cost of this amount of oxygen being provided by cylinders (at least K555,000) or an oxygen generator (about K1 million) is significantly more than the cost of setting up and maintaining a comprehensive system of bedside oxygen concentrators (K223,000). A district hospital will use 17,000 l per day. The full costs of this over 2 years are K33,000 if supplied by bedside concentrators, or K333,000 plus transport costs if the oxygen source is cylinders. In provincial and district hospitals bedside oxygen concentrators will be the most cost-effective, simple and reliable sources of oxygen. In large hospitals where there are existing oxygen pipelines, or in newly designed hospitals, an oxygen generator will be effective but currently much more expensive than bedside concentrators that provide the same volume of oxygen generation. There are options for oxygen concentrator use in hospitals and health centres that do not have reliable power. These include battery storage of power or solar power. While these considerably add to the establishment cost when changing from cylinders to concentrators, a battery-powered system should repay its capital costs in less than one year, though this has not yet been proven in the field. Bedside oxygen concentrators are currently the 'best-buy' in supplying oxygen in most hospitals in PNG, where cylinder oxygen is the largest single item in their drug budget. Oxygen concentrators should not be seen as an expensive intervention that has to rely on donor support, but as a cost-saving intervention for all hospitals.

Infants in Papua New Guinea (PNG) are at a high risk of invasive pneumococcal disease, and a substantial burden of this falls on children less than six months old. PNG is planning to introduce a pneumococcal conjugate vaccine for infants in the near future, but to make the maximum impact neonatal immunization will have to be considered. To provide evidence on safety and immunogenicity for neonatal and early infant immunization, we undertook an open randomized controlled trial of 7-valent pneumococcal conjugate vaccine (7vPCV). 318 children received 7vPCV at ages 0, 1 and 2 months or at 1, 2 and 3 months or not at all. All children received 23-valent pneumococcal polysaccharide vaccine at age 9 months. This was a large and complex trial: village reporters visited participants weekly during the first year and fortnightly for a further 6 months and nurses monitored self-reported morbidity and collected many thousands of biological samples. The study team was remarkably successful in achieving the study aims, with 18-month follow-up completed on 77% of enrolled children and over 80% of scheduled samples collected. While the results of the trial will be reported elsewhere, this paper discusses the design of the study and dissects out some of the main reasons for its successful completion. Strong community engagement was an essential factor in success and the principles of equitable partnership and service provision led to a strong research partnership. A two-stage consent process, comprising primary assent followed by later informed consent, led to a high drop-out before initial enrolment, but an outstanding retention of those enrolled in the study. We conclude that factors such as strong community participation, reciprocity and a good relationship between the study team and participants are just as important as the technical elements of laboratory testing and data handling in ensuring the success of a vaccine trial in PNG.