Combating infectious diseases in the Pacific Islands: sentinel surveillance, environmental health, and geospatial tools

Assessment of Environmental Impacts on Health: Examples from the Pacific Basin

Assessing environmental impacts on health in the Pacific Basin is challenged by significantly varying data types - quantities, qualities, and paucities - because of varying geographic sizes, environments, biodiversity, ecological assets, and human population densities, with highly varied and unequal socio-economic development and capacity to respond to environmental and health challenges. We discuss three case-based methodological examples from Pacific Basin environmental health impact assessments. These methods could be used to improve environmental health evidence at all country and regional levels across a spectrum of big data availability to no data. These methods are, 1) a risk assessment of airborne particulate matter in Korea based on the chemical composition of these particulates; 2) the use of system dynamics to appraise the influences of a range of environmental health determinants on child health outcomes in remote Solomon Islands; and 3) precision environmental public health methodologies based on comprehensive data collection, analyses, and modelling (including Bayesian belief networks and spatial epidemiology) increasing precision for good environmental health decision making to prevent and control a zoonotic disease in Fiji Islands. We show that while a common theme across the three examples is the value of high quality and quantity data to support stronger policy decisions and appropriate prioritizing of investment, it is also clear that for many countries in the Pacific Basin, sufficient data will remain a challenge to inform decision makers about environmental impact on health.

How community participation in water and sanitation interventions impacts human health, WASH infrastructure and service longevity in low-income and middle-income countries: a realist review

OBJECTIVE

To understand how, and under what circumstances community participation in water and sanitation interventions impacts the availability of safe water and sanitation, a change in health status or behaviour and the longevity of water, sanitation and hygiene (WASH) resources and services.

DESIGN

Realist review.

DATA SOURCES

PubMed, Web of Science and Scopus databases were used to identify papers from low-income and middle-income countries from 2010 to 2020.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Criteria were developed for papers to be included. The contribution of each paper was assessed based on its relevance and rigour (eg, can it contribute to context, mechanism or outcome, and is the method used to generate that information credible).

ANALYSIS

Inductive and deductive coding was used to generate context-mechanism-outcome configurations.

RESULTS

73 studies conducted in 29 countries were included. We identified five mechanisms that explained the availability, change and longevity outcomes: (1) accountability (policies and procedures to hold communities responsible for their actions and outcomes of an intervention), (2) diffusion (spread of an idea or behaviour by innovators over time through communication among members of a community), (3) market (the interplay between demand and supply of a WASH service or resource), (4) ownership (a sense of possession and control of the WASH service or resource) and (5) shame (a feeling of disgust in one's behaviour or actions). Contextual elements identified included community leadership and communication, technical skills and knowledge, resource access and dependency, committee activity such as the rules and management plans, location and the level of community participation.

CONCLUSIONS

The findings highlight five key mechanisms impacted by 19 contextual factors that explain the outcomes of community water and sanitation interventions. Policymakers, programme implementers and institutions should consider community dynamics, location, resources, committee activity and practices and nature of community participation, before introducing community water and sanitation interventions.

Leptospirosis in French Polynesia: 11 years of surveillance data, 2007-2017

Leptospirosis is a worldwide zoonosis with higher incidence in tropical areas and is a neglected disease in the Pacific region. French Polynesia (FP) is a French overseas territory located in the South Pacific. Data on the epidemiology in FP are scarce. In this study, we describe our understanding of leptospirosis epidemiology in FP and discuss the prospects concerning this disease and its surveillance to better address preventive actions. We report 11 years of surveillance data between 1 January 2007 and 31 December 2017. Over the study period, 1356 confirmed and probable leptospirosis cases were reported. The mean annual incidence rate was 46.0 (95% confidence interval, 43.6-48.5) cases per 100 000 inhabitants. We registered 864 (63.7%) hospitalizations; of these, at least 270 (19.9%) were in the intensive care unit, and 24 patients (1.8%) died. Even if the incidence of leptospirosis is lower in FP compared to most of other Pacific countries and territories, our data confirm that the disease is highly endemic in FP. Despite all the preventive measures taken, leptospirosis remains a major public health concern in FP, thus highlighting the need to maintain intensive leptospirosis surveillance, medical staff training and provision of information to the general population.

The extensive networks of frequent population mobility in the Samoan Islands and their implications for infectious disease transmission

Population mobility has been demonstrated to contribute to the persistent transmission and global diffusion of epidemics. In the Pacific Islands, population mobility is particularly important for emerging infectious diseases, disease elimination programs, and diseases spread by close contact. The extent of population mobility between American Samoa villages, Samoa districts and other countries was investigated based on travel data collected during community surveys in American Samoa in 2010 and 2014. Within American Samoa, workers commuted daily across the whole of the main island of Tutuila, with work hubs drawing from villages across the island. Of the 670 adult workers surveyed, 37% had traveled overseas in the past year, with 68% of trips to Samoa. Of children aged 8–13 years (n = 337), 57% had traveled overseas, with 55% of trips to Samoa. An extensive network of connections between American Samoa villages and Samoa districts was demonstrated, with most trips lasting one week to one month. Our study showed that populations in the Samoan islands are highly mobile, and quantified the extent and destinations of their travels. Our findings offer insight into the impact of population mobility on the transmission of infectious diseases and data to refine existing models of disease transmission in the Pacific islands.

A systematic review of human and animal leptospirosis in the Pacific Islands reveals pathogen and reservoir diversity

Background

The Pacific Islands have environmental conditions highly favourable for transmission of leptospirosis, a neglected zoonosis with highest incidence in the tropics, and Oceania in particular. Recent reports confirm the emergence and outbreaks of leptospirosis in the Pacific Islands, but the epidemiology and drivers of transmission of human and animal leptospirosis are poorly documented, especially in the more isolated and less developed islands.

Methodology/Principal findings

We conducted a systematic review of human and animal leptospirosis within 25 Pacific Islands (PIs) in Polynesia, Melanesia, Micronesia, as well as Easter Island and Hawaii. We performed a literature search using four international databases for articles published between January 1947 and June 2017. We further included grey literature available on the internet. We identified 148 studies describing leptospirosis epidemiology, but the number of studies varied significantly between PIs. No data were available from four PIs. Human leptospirosis has been reported from 13 PIs, with 63% of all studies conducted in Hawaii, French Polynesia and New Caledonia. Animal leptospirosis has been investigated in 19 PIs and from 14 host species, mainly pigs (18% of studies), cattle (16%) and dogs (11%). Only 13 studies provided information on both human and animal leptospirosis from the same location. Serology results were highly diverse in the region, both in humans and animals.

Conclusions/Significance

Our study suggests that, as in other tropical regions, leptospirosis is widespread in the PIs while showing some epidemiological heterogeneity. Data are scarce or absent from many PIs. Rodents, cattle, pigs and dogs are all likely to be important carriers, but the relative importance of each animal species in human infection needs to be clarified. Epidemiological surveys with appropriate sampling design, pathogen typing and data analysis are needed to improve our understanding of transmission patterns and to develop effective intervention strategies.

Leptospirosis is an important bacterial zoonosis that affects people and animals worldwide. It is common in tropical areas, especially in island ecosystems. Because islands are relatively small, isolated, and have limited health and diagnostic facilities, the disease burden is often underestimated. In this systematic review, we aimed to describe the extent of leptospirosis in the Pacific Islands, including the diversity of pathogens and animal reservoirs. We identified 148 studies from 21 Pacific islands that described Leptospira infection in humans or animals. In hospitalized febrile patients, leptospirosis was a common cause of the acute febrile illness, but accurate diagnosis was challenging and often delayed because symptoms overlapped with many other infectious diseases, and access to laboratory diagnosis was limited. A wide variety of animal hosts of Leptospira were identified, with rodents, cattle, pigs and dogs reported as important hosts; however, their relative importance in human infection remains unclear. Our review demonstrates that the epidemiology of leptospirosis varies across the Pacific Islands, but information about risk factors and transmission routes is currently limited. We recommend more integrated studies, using an eco-epidemiological approach that includes human, veterinary and environmental factors, and interactions between factors at different ecological scales.