A marked decline in the incidence of malaria in a remote region of Malaita, Solomon Islands, 2008 to 2013

Oloifana-Polosovai, Hellen; Gwala, John; Harrington, Humpress; Massey, Peter; Ribeyro, Elmer; Flores, Angélica; Speare, Christopher; McBride, Edwin; MacLaren, David; Speare, Rick

doi:10.5365/wpsar.2014.5.3.002

Cited by 7 publications

(4 citation statements)

References 9 publications

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“…However, it has been previously recognized that the accuracy of clinical malaria case reporting in primary health care facilities in Solomon Islands is often relatively poor [42]. In addition, the results of this study are well in line with the changes observed at a remote region of Malaita, the neighbouring island to Ngella, where in parallel with a 91% reduction in all malaria cases, the proportion of clinical cases due to P. vivax increased from 33% in 2008 to 84% in 2013 [43]. While further studies will be required to determine the relative contribution of P. falciparum and P. vivax to the burden of clinical malaria in Ngella, data of this study make it clear that the very high burden of asymptomatic, low-density P. vivax infections is the key challenge to future malaria elimination in Ngella.…”

Section: Discussionsupporting

confidence: 86%

Molecular epidemiology of residual Plasmodium vivax transmission in a paediatric cohort in Solomon Islands

Quah

Waltmann

Karl

et al. 2019

Malar J

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Background Following the scale-up of intervention efforts, malaria burden has decreased dramatically in Solomon Islands (SI). Submicroscopic and asymptomatic Plasmodium vivax infections are now the major challenge for malaria elimination in this country. Since children have higher risk of contracting malaria, this study investigated the dynamics of Plasmodium spp. infections among children including the associated risk factors of residual P. vivax burden. Methods An observational cohort study was conducted among 860 children aged 0.5–12 years in Ngella (Central Islands Province, SI). Children were monitored by active and passive surveillances for Plasmodium spp. infections and illness. Parasites were detected by quantitative real-time PCR (qPCR) and genotyped. Comprehensive statistical analyses of P. vivax infection prevalence, molecular force of blood stage infection ( mol FOB) and infection density were conducted. Results Plasmodium vivax infections were common (overall prevalence: 11.9%), whereas Plasmodium falciparum infections were rare (0.3%) but persistent. Although children acquire an average of 1.1 genetically distinct P. vivax blood-stage infections per year, there was significant geographic heterogeneity in the risks of P. vivax infections across Ngella (prevalence: 1.2–47.4%, p < 0.01; mol FOB: 0.05–4.6/year, p < 0.01). Malaria incidence was low (IR: 0.05 episodes/year-at-risk). Age and measures of high exposure were the key risk factors for P. vivax infections and disease. Malaria incidence and infection density decreased with age, indicating significant acquisition of immunity. G6PD deficient children (10.8%) that did not receive primaquine treatment had a significantly higher prevalence ( a OR: 1.77, p = 0.01) and increased risk of acquiring new bloodstage infections ( mol FOB a IRR: 1.51, p = 0.03), underscoring the importance of anti-relapse treatment. Conclusion Residual malaria transmission in Ngella exhibits strong heterogeneity and is characterized by a high proportion of submicroscopic and asymptomatic P. vivax infections, alongside sporadic P. falciparum infections. Implementing an appropriate primaquine treatment policy to prevent P. vivax relapses and specific targeting of control interventions to high risk areas will be required to accelerate ongoing control and elimination activities. Electronic supplementary material The online version of this article (10.1186/s12936-019-2727-9) contains su...

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Section: Discussionsupporting

confidence: 86%

Molecular epidemiology of residual Plasmodium vivax transmission in a paediatric cohort in Solomon Islands

Quah

Waltmann

Karl

et al. 2019

Malar J

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“…2 In 2014 the rate of confirmed cases of malaria was 44 per 1000 person years. 3 Malaria has been reported to have declined as a cause of fever in some parts of the Solomon Islands in the last ten years 4 but remains an important public health problem.…”

Section: Introductionmentioning

confidence: 99%

Incidental mosquitocidal effect of an ivermectin mass drug administration on Anopheles farauti conducted for scabies control in the Solomon Islands

Kositz

Talina²,

Diau³

et al. 2017

Transactions of the Royal Society of Tropical Medicine and Hygiene

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BackgroundThe Solomon Islands is targeting elimination of malaria by 2030. The dominant vector is the predominantly exophagic, exophilic Anopheles farauti sensu strictu. This biting behaviour limits the efficacy of conventional vector control tools and highlights the need for new strategies. When administered to humans ivermectin has been shown to have a mosquitocidal effect. Mass drug administration (MDA) with ivermectin is an emerging strategy in the control of scabies. In this study we explored any incidental effect of ivermectin MDA conducted for scabies control on mosquitoes.MethodsMDA for scabies was conducted in three villages. We performed human landing catches and measured 5-day mortality amongst Anopheles mosquitoes caught before and after MDA. Cox regression was used to calculate hazard ratios (HR) for mortality between mosquitoes caught before and after MDA.ResultsThere was a significant increase in 5-day mortality in anopheline mosquitoes caught post-MDA which was highest on the day of MDA itself (HR 4.2 95% CI 1.8 to 10.1, p=0.001) and the following day (HR 4.4 95% CI 1.8 to 10.8, p=0.002) compared to mosquitoes caught before MDA.ConclusionsThis study shows a possible mosquitocidal effect of ivermectin MDA conducted for scabies control. Studies with a larger sample size with clinical as well as entomological outcomes should be conducted in this population.

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“…The proportion of malaria that causes fever has been declining in some parts of Solomon Islands from 2008 to 2013. ( 9 ) Studies in nearby countries including West Papua, Indonesia have shown rickettsia infections are a common cause of acute infections that lead to hospitalization. ( 10 ) Results of our study may give some insights for the incidence of rickettsia infections in Solomon Islands; however, in the absence of routine testing, the proportion of rickettsial infections that causes febrile illnesses in Solomon Islands is still unclear.…”

Section: Discussionmentioning

confidence: 99%

An outbreak investigation of scrub typhus in Western Province, Solomon Islands, 2014

Marks

Joshua²,

Longbottom³

et al. 2016

WPSAR

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ObjectiveTo identify the etiology and risk factors of undifferentiated fever in a cluster of patients in Western Province, Solomon Islands, May 2014.MethodsAn outbreak investigation with a case control study was conducted. A case was defined as an inpatient in one hospital in Western Province, Solomon Islands with high fever (> 38.5 °C) and a negative malaria microscopy test admitted between 1 and 31 May 2014. Asymptomatic controls matched with the cases residentially were recruited in a ratio of 1:2. Serum samples from the subjects were tested for rickettsial infections using indirect micro-immunofluorescence assay.ResultsNine cases met the outbreak case definition. All cases were male. An eschar was noted in five cases (55%), and one developed pneumonitis. We did not identify any environmental factors associated with illness. Serum samples of all five follow-up cases (100%) had strong-positive IgG responses to scrub typhus. Nine out of ten controls were negative for ST antibodies. Four controls had low levels of antibodies against spotted fever group rickettsia, and only one had a low-level response to typhus group rickettsia.DiscussionThis outbreak represents the first laboratory-confirmed outbreak of scrub typhus in the Western Province of Solomon Islands. The results suggest that rickettsial infections are more common than currently recognized as a cause of an acute febrile illness. A revised clinical case definition for rickettsial infections and treatment guidelines were developed and shared with provincial health staff for better surveillance and response to future outbreaks of a similar kind.

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A marked decline in the incidence of malaria in a remote region of Malaita, Solomon Islands, 2008 to 2013

Cited by 7 publications

References 9 publications

Molecular epidemiology of residual Plasmodium vivax transmission in a paediatric cohort in Solomon Islands

Molecular epidemiology of residual Plasmodium vivax transmission in a paediatric cohort in Solomon Islands

Incidental mosquitocidal effect of an ivermectin mass drug administration on Anopheles farauti conducted for scabies control in the Solomon Islands

An outbreak investigation of scrub typhus in Western Province, Solomon Islands, 2014

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