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. 2018 Oct 3;11(1):535.
doi: 10.1186/s13071-018-3107-y.

Spatial distribution and populations at risk of A. lumbricoides and T. trichiura co-infections and infection intensity classes: an ecological study

Kei Owada  1   2 , Colleen L Lau  3   4 , Lydia Leonardo  5 , Archie C A Clements  4 , Laith Yakob  6 , Mark Nielsen  7   8 , Hélène Carabin  9 , Ricardo J Soares Magalhães  3   10
Affiliations

Spatial distribution and populations at risk of A. lumbricoides and T. trichiura co-infections and infection intensity classes: an ecological study

Kei Owada et al. Parasit Vectors. .

Abstract

Background: Soil-transmitted helminth (STH) infections are highly prevalent in the Philippines. Mapping the prevalence and high-intensity of STH co-infections can help guide targeted intervention programmes to reduce morbidity, especially among vulnerable school-aged children. In this study, we aimed to predict the spatial distribution of the prevalence of Ascaris lumbricoides and Trichuris trichiura co-infection and infection intensity classes in the Philippines to identify populations most in need of interventions.

Methods: Data on STH infections from 29,919 individuals during the nationwide parasitological survey in 2005 to 2007 were included in the analysis. To geographically predict the prevalence of A. lumbricoides and T. trichiura co-infections and infection intensity classes, Bayesian multinomial geostatistical models were built including age, sex, environmental variables and a geostatistical random effect. The number of individuals co-infected and belonging to each of the infection intensity classes in 2017 was forecast by combining our predictive prevalence maps with population density maps.

Results: Our models showed that school-aged children (5-19 years) are most at risk of A. lumbricoides and T. trichiura co-infections and of moderate/high infection intensity compared to other age groups. We identified target provinces where the likelihood of STH-associated morbidity was highest: Luzon (Bulacan, Benguet, Cavite, Sorsogon, Metropolitan Manila, Pampanga and Rizal), the Visayas (Cebu, Iloilo, Leyte and Negros Occidental), and in Mindanao (Agusan Del Norte, Davao Del Sur, Davao Oriental, Lanao Del Sur, Maguindanao, Misamis Oriental, Sulu and Zamboanga Del Sur). Luzon had the highest estimated number of school-aged children with A. lumbricoides and T. trichiura co-infections (estimated total 89,400), followed by the Visayas (38,300) and Mindanao (20,200).

Conclusions: Our study provided epidemiological evidence to highlight national priority areas for controlling co-infections and high intensity infections in the Philippines. Our maps could assist more geographically targeted interventions to reduce the risk of STH-associated morbidity in the Philippines.

Keywords: Ascaris lumbricoides; Bayesian geostatistics; Co-infection; Infection intensity; Soil-transmitted helminths; Spatial epidemiology; The Philippines; Trichuris trichiura.

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Conflict of interest statement

Ethics approval and consent to participate

Ethical clearance for this analytical study was provided by the University of Queensland School of Medicine Low Risk Ethical Review Committee (clearance number 2014-SOMILRE-0100).

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Predicted prevalence of A. lumbricoides mono- (a), T. trichiura mono- (b), and co-infections (c) in school-aged children in the Philippines. Note: the overall mean predicted prevalences are specific to the age and sex group (choice of a different age-sex group would result in a different spatial mean), with spatial variation around the mean being influenced by the environmental variables and the spatial correlation component of the model
Fig. 2
Fig. 2
Predicted prevalence of light infection intensity class (a) and moderate/high infection intensity classes (b) of A. lumbricoides in school-aged children in the Philippines
Fig. 3
Fig. 3
Predicted prevalence of light infection intensity class (a) and moderate/high infection intensity classes (b) of T. trichiura in school-aged children in the Philippines
See this image and copyright information in PMC

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