Prevalence of malaria across Papua New Guinea after initial roll‐out of insecticide‐treated mosquito nets

Abstract

Abstractobjectives To assess the population prevalence of malaria in villages across Papua New Guinea (PNG) following the first roll-out of free long-lasting insecticidal nets (LLIN). results Malaria prevalence ranged from 0% to 49.7% with a weighted average of 12.1% (95% CI 9.5, 15.3) in the national sample. More people were infected with Plasmodium falciparum (7.0%; 95% CI 5.4, 9.1) than with P. vivax (3.8%; 95% CI 2.4, 5.7) or P. malariae (0.3%; 95% CI 0.1, 0.6). Parasitaemia was strongly age-dependent with a P. falciparum peak at age 5-9 years and a P. vivax peak at age 1-4 years, yet with differences between geographical regions. Individual LLIN use and high community coverage were associated with reduced odds of infection (OR = 0.64 and 0.07, respectively; both P < 0.001). Splenomegaly in children and anaemia were common morbidities attributable to malaria.conclusions Malaria prevalence across PNG is again at levels comparable to the 1970s. The strong association of LLIN use with reduced parasitaemia supports efforts to achieve and maintain high country-wide coverage. P. vivax infections will require special targeted approaches across PNG.

Higher Complexity of Infection and Genetic Diversity of Plasmodium vivax Than Plasmodium falciparum Across All Malaria Transmission Zones of Papua New Guinea

“…For P. falciparum Pfmsp2, however, only 20% of all genotyped samples had polyclonal infections and there was a much lower mean MOI of 1.39, despite the higher prevalence of P. falciparum than P. vivax in many areas. 30 The contrasting complexity of infection for the two species is comparable to previous reports from the PNG north coast 39,68 and demonstrates that this pattern is also observed across areas with widely varying endemicity including areas with low parasite prevalence. 30 This may be in part due to lower transmission areas having increasing proportions of imported infections, which reflects the MOI and diversity of the infection origin, 22,69,70 and this effect would be enhanced for P. vivax by the fact that relapse can occur 1-3 years after the primary infection.…”

“…Despite significant variability of P. vivax prevalence among geographic areas, 30 polyclonality (mean = 70.8%, range = 52.5-93.0%) and MOI (mean = 2.32, range = 1.8-2.7) based on the two markers combined were high in all geographic areas ( Figure 2A, Supplemental Table 2). For P. falciparum, lower and more variable polyclonality (mean = 21.5%, range = 0-47.1%) and mean MOI (mean = 1.4, range = 1-1.6) were Table 3).…”

“…This survey included 49 villages from 16 provinces, which had already covered by free LLIN and 19 villages from six sentinel sites pre-LLIN distribution. 30 Further details of the survey methodology are published elsewhere. 29,30 We assigned the villages to 27 "geographic clusters" predicted to harbor distinct parasite populations on the basis of topography and predicted human movement ( Figure 1, Supplemental Table 1).…”

“…30 Further details of the survey methodology are published elsewhere. 29,30 We assigned the villages to 27 "geographic clusters" predicted to harbor distinct parasite populations on the basis of topography and predicted human movement ( Figure 1, Supplemental Table 1). Genomic DNA was extracted from whole-blood samples using the QiaAmp DNA Extraction Kit (Qiagen, Chadstone, Victoria, Australia) or the Favorprep TM genomic DNA extraction kit (Favorgen, Ping-Tung, Taiwan).…”

“…E-mail: barry@wehi.edu.au was associated with LLIN use, strongly supporting the application of this strategy to control malaria in PNG. 30 New tools are needed to monitor the success of malaria control programs. Molecular epidemiology can provide such a tool, by providing deeper insight into parasite transmission intensity than traditional prevalence surveys by measuring the complexity of infection and population genetic diversity accumulating as a result of co-transmission of multiple genetically distinct clones.…”