Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

Vinit, Rebecca J, Timinao, Lincoln, Bubun, Nakei, Katusele, Michelle, Robinson, Leanne J, Kaman, Peter B, Sakur, Muker, Makita, Leo S, Reimer, Lisa ORCID: https://orcid.org/0000-0002-9711-4981, Schofield, Louis, Pomat, William, Mueller, Ivo, Laman, Moses, Freeman, Tim and Karl, Stephan (2020) 'Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea'. Nature Communications, Vol 11, p. 3646.

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Abstract

Background: Papua New Guinea (PNG) has the highest malaria transmission outside of Africa and long-lasting insecticidal nets (LLIN) are the only vector-control tool distributed country-wide. LLIN were introduced into PNG in about 2005 and have been attributed to have had a huge impact on malaria transmission, with reductions in malaria prevalence observed from 15.7% (2008) to 1% (2014). Since 2015, malaria indicators in PNG have risen significantly. Similar trends have been observed in several African nations. In the present study, we observed a drastic reduction in bioefficacy of LLIN collected both from communities (used nets) and prior to use (new nets). We hypothesise that decreased bioefficacy of LLINs is a major contributor to the observed malaria resurgence in PNG and possibly in other parts of the world. Methods: New LLIN in original and unopened packaging (n=192) with a range of manufacturing dates from 2007-2019 were collected either directly from consignments or from households in 15 PNG provinces. Used LLIN (n=40) were collected in 2 provinces, with manufacturing dates ranging from 2008-2017. LLIN were subjected to standard WHO cone bioassays using fully susceptible An. farauti mosquitoes. A subset of LLIN was re-tested using fully susceptible An. gambiae mosquitoes in order to ensure reproducibility of results. Results: Only 7% (95% CI 4-12%) of new LLIN manufactured between 2013-2019 exhibited 100% mortality. However, 84% (95%CI: 65-84%) new nets manufactured in 2012 or before exhibited 100% mortality. Only 29 % of used LLIN less than 3 years old exhibited > 80% 24h-mortality. Results obtained in tests using An. farauti corresponded well with confirmatory tests conducted using An. gambiae. Discussion: Bioefficacy of LLIN in PNG appears to have been highly variable since 2013, with few nets manufactured since 2013 meeting WHO standards. This time-frame coincides with malaria resurgence in the country. These results may have ramifications for LLIN-based malaria control that go beyond the local PNG scenario.

Item Type:	Article
Subjects:	QX Parasitology > QX 4 General works QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes WA Public Health > Preventive Medicine > WA 240 Disinfection. Disinfestation. Pesticides (including diseases caused by) WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria
Faculty: Department:	Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):	https://doi.org/10.1038/s41467-020-17456-2
Depositing User:	Samantha Sheldrake
Date Deposited:	21 Jul 2020 11:08
Last Modified:	21 Jul 2020 11:08
URI:	https://archive.lstmed.ac.uk/id/eprint/14912

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