The epidemiology of malaria in the Papua New Guinea highlands: 7. Southern Highlands Province

As the last part of a program to survey the extent of malaria transmission in the Papua New Guinea highlands, a series of rapid malaria surveys were conducted in 2003-2004 and 2005 in different parts of Southern Highlands Province. Malaria was found to be highly endemic in Lake Kutubu (prevalence rate (PR): 17-33%), moderate to highly endemic in Erave (PR: 10-31%) and moderately endemic in low-lying parts (< 1500 m) of Poroma and Kagua (PR: 12-17%), but was rare or absent elsewhere. A reported malaria epidemic prior to the 2004 surveys could be confirmed for the Poroma (PR: 26%) but not for the lower Kagua area. In Kutubu/Erave Plasmodium falciparum was the most common cause of infection (42%), followed by P. vivax (39%) and P. malariae (16%). In other areas most infections were due to P. vivax (63%). Most infections were of low density (72% < 500/ microl) and not associated with febrile illness. Overall, malaria was only a significant source of febrile illness when prevalence rates rose above 10%, or in epidemics. However, concurrent parasitaemia led to a significant reduction in haemoglobin (Hb) level (1.2 g/dl, CI95: [1.1-1.4.], p < 0.001) and population mean Hb levels were strongly correlated with overall prevalence of malarial infections (r = -0.79, p < 0.001). Based on the survey results, areas of different malaria epidemiology are delineated and options for control in each area are discussed.

A neonatal pneumococcal conjugate vaccine trial in Papua New guinea: study population, methods and operational challenges

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.