The American Journal of Tropical Medicine and Hygiene
Mosquito repellents are important for personal protection against nuisance and potentially infect... more Mosquito repellents are important for personal protection against nuisance and potentially infectious mosquito bites. Repellent activity of Australian blue cypress essential oil (EO) and a commercially formulated skin lotion containing blue cypress EO (topical formulation) were compared with 20% DEET (N, N-diethyl-3 toluamide) against mosquitoes under laboratory and field conditions in North Queensland, Australia. On a volunteer’s forearm, 1 mL of candidate material was applied to approximately 600 cm2 of exposed skin. When blue cypress EO was applied at various concentrations (0.5%–10.5%), it did not fully prevent mosquito landing or biting. However, a dose–dependent increase, approaching 80% protection, was observed at high EO concentrations. On the basis of these results, three concentrations (5%, 10%, and 20%) of blue cypress EO were selected for complete protection time (CPT) experiments. Topical formulation (undiluted) was also included in CPT experiments. Although some protec...
Mosquito repellents are important for personal protection against nuisance and potentially infect... more Mosquito repellents are important for personal protection against nuisance and potentially infectious mosquito bites. Repellent activity of Australian Blue Cypress (ABC) essential oil and a commercially formulated skin lotion containing ABC oil were compared with 20% DEET and evaluated against mosquitoes under laboratory and field conditions in North Queensland, Australia. Using the arm-in-cage method, the following cumulative doses of ABC oil in ethanol were tested; 0.5%, 1.5%, 3%, 5%, 7.5% and 10.5% against female Aedes aegypti. In the field, 2.5%, 5% and 10% of diluted ethanolic ABC oil were tested using the human landing catch method. We observed a dose-dependent increase in protection with diluted ABC oil approaching 80% at high concentrations. While some protection was afforded, mosquito landing and probing was still recorded immediately after application (laboratory) for both ABC essential oil and skin lotion. Protection declined from 80-70% and 93-50% for 20% ABC oil (labora...
Introduction: Long lasting insecticidal nets (LLINs) play a key role in reducing malaria transmis... more Introduction: Long lasting insecticidal nets (LLINs) play a key role in reducing malaria transmission in endemic countries. Previously, we demonstrated a substantial decrease in the bioefficacy of LLINs for malaria prevention delivered to Papua New Guinea (PNG) between 2013 and 2019. This coincided with a rise in malaria cases in the country. The present study was aimed at determining the underlying cause of the observed reduced bioefficacy of these LLINs. In particular, we tested the hypothesis that a change in the coating formulation of the respective LLIN product was the cause for the observed reduction in bioefficacy, and had led to completely altered product properties and performance. Methods A set of PermaNet® 2.0 LLIN samples (n = 12) manufactured between 2007 and 2019 was subjected to combustion ion chromatography in order to understand the chemistry of the LLIN polymer coating formulation. In addition, World Health Organization (WHO) LLIN wash tests and cone bioassays were...
/SummaryIn a study published in Nature Communications in August 2020, we demonstrated an abrupt d... more /SummaryIn a study published in Nature Communications in August 2020, we demonstrated an abrupt decrease in the bioefficacy of long-lasting insecticidal nets (LLINs) for malaria prevention delivered to Papua New Guinea (PNG) between 2012 and 2013. This coincided with a rise in malaria cases in the country. At the time of publication of the original article, we were unable to pinpoint the exact reasons for the observed shift towards inferior product performance and stated that ‘further studies are required to determine the underlying cause of the observed reduced bioefficacy of these LLINs’ 1. Due to the potentially significant public health implications (hundreds of millions of this specific LLIN product had been distributed globally), our study led to discussions and speculation among stakeholders. Here, we present data unequivocally showing that the observed reduction in the ability to kill mosquitoes of these LLINs is a direct result of a manufacturing change that occurred at the same time.
Gastrointestinal parasites of livestock cause diseases of important socioeconomic concern worldwi... more Gastrointestinal parasites of livestock cause diseases of important socioeconomic concern worldwide. The two main types of intestinal parasites are helminths and protozoa. They can cause high mortality, reduce production and lead to significant overall economic losses. In tropical and subtropical areas, parasitic nematodes are recognised as a limiting factor to the expansion and improvement of smallholder production of small ruminants. In addition to their veterinary importance, some parasites of domesticated livestock can also be transmitted to companion animals and wildlife, and are a threat to public health. Little is known of the prevalence of internal pathogens in domesticated animals or wildlife in Papua New Guinea (PNG). There have been various reports on gastrointestinal helminth and Eimeria infections in sheep and goats in PNG. However, those surveys have been restricted in their geographical range and have only been performed on animals raised in government or institutiona...
The American Journal of Tropical Medicine and Hygiene, 2022
Vector surveillance is important to control mosquito-borne diseases. We compared the efficacies o... more Vector surveillance is important to control mosquito-borne diseases. We compared the efficacies of three mosquito-trapping devices: the CDC light trap with incandescent light (CDC_I), the CDC light trap with ultraviolet light (CDC_UV), and the Biogents-sentinel (BG) trap, to identify a suitable and cost-effective surveillance tool for key vectors of neglected zoonotic arboviral diseases in Papua New Guinea (PNG). Of 13,788 female mosquitoes, CDC_I caught 7.9%, BG caught 14.5%, and CDC_UV caught 77.6%. Culex was the most predominant genus caught in all the traps. Centers for Disease Control light trap with ultraviolet light trap captured the highest abundance, highest species richness of mosquitoes and exhibited the highest overall Culex mosquito capture rates compared with BG and CDC_l. This study represents the first assessment of trapping devices for zoonotic arbovirus vectors in PNG. We recommend the CDC _UV trap for future monitoring and surveillance of infectious arboviral vect...
Gastrointestinal parasites of livestock cause diseases of important socio-economic concern worldw... more Gastrointestinal parasites of livestock cause diseases of important socio-economic concern worldwide. The present study investigated the prevalence of gastrointestinal parasites in sheep and goats in lowland and highland regions of Papua New Guinea (PNG). Faecal samples were collected from a total of 165 small ruminants (110 sheep and 55 goats) from February to April 2011. Analysis by a modified McMaster technique revealed that 128 animals (72% of sheep and 89% of goats) were infected with one or more species of gastrointestinal parasites. The gastrointestinal parasites found and their prevalences in sheep (S) and in goats (G) were as follows: strongyle 67.3% (S), 85.5% (G); Eimeria 17.3% (S), 16.4% (G); Strongyloides, 8.2% (S), 23.6% (G); Fasciola, 5.5% (S), 18.2% (G); Trichuris, 1.8% (S), 3.6% (G); and Nematodirus, 1.8% (S), 3.6% (G). Two additional genera were found in goats: Moniezia (9.1%) and Dictocaulus (3.6%). This is the first study to quantitatively examine the prevalence ...
The American Journal of Tropical Medicine and Hygiene
Mosquito repellents are important for personal protection against nuisance and potentially infect... more Mosquito repellents are important for personal protection against nuisance and potentially infectious mosquito bites. Repellent activity of Australian blue cypress essential oil (EO) and a commercially formulated skin lotion containing blue cypress EO (topical formulation) were compared with 20% DEET (N, N-diethyl-3 toluamide) against mosquitoes under laboratory and field conditions in North Queensland, Australia. On a volunteer’s forearm, 1 mL of candidate material was applied to approximately 600 cm2 of exposed skin. When blue cypress EO was applied at various concentrations (0.5%–10.5%), it did not fully prevent mosquito landing or biting. However, a dose–dependent increase, approaching 80% protection, was observed at high EO concentrations. On the basis of these results, three concentrations (5%, 10%, and 20%) of blue cypress EO were selected for complete protection time (CPT) experiments. Topical formulation (undiluted) was also included in CPT experiments. Although some protec...
Mosquito repellents are important for personal protection against nuisance and potentially infect... more Mosquito repellents are important for personal protection against nuisance and potentially infectious mosquito bites. Repellent activity of Australian Blue Cypress (ABC) essential oil and a commercially formulated skin lotion containing ABC oil were compared with 20% DEET and evaluated against mosquitoes under laboratory and field conditions in North Queensland, Australia. Using the arm-in-cage method, the following cumulative doses of ABC oil in ethanol were tested; 0.5%, 1.5%, 3%, 5%, 7.5% and 10.5% against female Aedes aegypti. In the field, 2.5%, 5% and 10% of diluted ethanolic ABC oil were tested using the human landing catch method. We observed a dose-dependent increase in protection with diluted ABC oil approaching 80% at high concentrations. While some protection was afforded, mosquito landing and probing was still recorded immediately after application (laboratory) for both ABC essential oil and skin lotion. Protection declined from 80-70% and 93-50% for 20% ABC oil (labora...
Introduction: Long lasting insecticidal nets (LLINs) play a key role in reducing malaria transmis... more Introduction: Long lasting insecticidal nets (LLINs) play a key role in reducing malaria transmission in endemic countries. Previously, we demonstrated a substantial decrease in the bioefficacy of LLINs for malaria prevention delivered to Papua New Guinea (PNG) between 2013 and 2019. This coincided with a rise in malaria cases in the country. The present study was aimed at determining the underlying cause of the observed reduced bioefficacy of these LLINs. In particular, we tested the hypothesis that a change in the coating formulation of the respective LLIN product was the cause for the observed reduction in bioefficacy, and had led to completely altered product properties and performance. Methods A set of PermaNet® 2.0 LLIN samples (n = 12) manufactured between 2007 and 2019 was subjected to combustion ion chromatography in order to understand the chemistry of the LLIN polymer coating formulation. In addition, World Health Organization (WHO) LLIN wash tests and cone bioassays were...
/SummaryIn a study published in Nature Communications in August 2020, we demonstrated an abrupt d... more /SummaryIn a study published in Nature Communications in August 2020, we demonstrated an abrupt decrease in the bioefficacy of long-lasting insecticidal nets (LLINs) for malaria prevention delivered to Papua New Guinea (PNG) between 2012 and 2013. This coincided with a rise in malaria cases in the country. At the time of publication of the original article, we were unable to pinpoint the exact reasons for the observed shift towards inferior product performance and stated that ‘further studies are required to determine the underlying cause of the observed reduced bioefficacy of these LLINs’ 1. Due to the potentially significant public health implications (hundreds of millions of this specific LLIN product had been distributed globally), our study led to discussions and speculation among stakeholders. Here, we present data unequivocally showing that the observed reduction in the ability to kill mosquitoes of these LLINs is a direct result of a manufacturing change that occurred at the same time.
Gastrointestinal parasites of livestock cause diseases of important socioeconomic concern worldwi... more Gastrointestinal parasites of livestock cause diseases of important socioeconomic concern worldwide. The two main types of intestinal parasites are helminths and protozoa. They can cause high mortality, reduce production and lead to significant overall economic losses. In tropical and subtropical areas, parasitic nematodes are recognised as a limiting factor to the expansion and improvement of smallholder production of small ruminants. In addition to their veterinary importance, some parasites of domesticated livestock can also be transmitted to companion animals and wildlife, and are a threat to public health. Little is known of the prevalence of internal pathogens in domesticated animals or wildlife in Papua New Guinea (PNG). There have been various reports on gastrointestinal helminth and Eimeria infections in sheep and goats in PNG. However, those surveys have been restricted in their geographical range and have only been performed on animals raised in government or institutiona...
The American Journal of Tropical Medicine and Hygiene, 2022
Vector surveillance is important to control mosquito-borne diseases. We compared the efficacies o... more Vector surveillance is important to control mosquito-borne diseases. We compared the efficacies of three mosquito-trapping devices: the CDC light trap with incandescent light (CDC_I), the CDC light trap with ultraviolet light (CDC_UV), and the Biogents-sentinel (BG) trap, to identify a suitable and cost-effective surveillance tool for key vectors of neglected zoonotic arboviral diseases in Papua New Guinea (PNG). Of 13,788 female mosquitoes, CDC_I caught 7.9%, BG caught 14.5%, and CDC_UV caught 77.6%. Culex was the most predominant genus caught in all the traps. Centers for Disease Control light trap with ultraviolet light trap captured the highest abundance, highest species richness of mosquitoes and exhibited the highest overall Culex mosquito capture rates compared with BG and CDC_l. This study represents the first assessment of trapping devices for zoonotic arbovirus vectors in PNG. We recommend the CDC _UV trap for future monitoring and surveillance of infectious arboviral vect...
Gastrointestinal parasites of livestock cause diseases of important socio-economic concern worldw... more Gastrointestinal parasites of livestock cause diseases of important socio-economic concern worldwide. The present study investigated the prevalence of gastrointestinal parasites in sheep and goats in lowland and highland regions of Papua New Guinea (PNG). Faecal samples were collected from a total of 165 small ruminants (110 sheep and 55 goats) from February to April 2011. Analysis by a modified McMaster technique revealed that 128 animals (72% of sheep and 89% of goats) were infected with one or more species of gastrointestinal parasites. The gastrointestinal parasites found and their prevalences in sheep (S) and in goats (G) were as follows: strongyle 67.3% (S), 85.5% (G); Eimeria 17.3% (S), 16.4% (G); Strongyloides, 8.2% (S), 23.6% (G); Fasciola, 5.5% (S), 18.2% (G); Trichuris, 1.8% (S), 3.6% (G); and Nematodirus, 1.8% (S), 3.6% (G). Two additional genera were found in goats: Moniezia (9.1%) and Dictocaulus (3.6%). This is the first study to quantitatively examine the prevalence ...
Uploads