Ivermectin Treatment of Livestock for Malaria Control on Sumba Island

Progress against malaria has stalled. New ways to control malaria are urgently needed to aid malaria elimination efforts both globally and in Indonesia. Ivermectin is a drug that can be safely given to humans or animals that makes their blood lethal to Anopheles mosquitoes that transmit malaria. It has been shown in Indonesia that ownership of livestock increases the risk of malaria transmission, and people on Sumba Island keep their livestock underneath their house, potentially attracting more Anopheles and increasing their risk of contracting malaria. We propose to treat livestock with ivermectin and evaluate how effective this is against wild Anopheles on Sumba. This control measure could interrupt the transmission of malaria if deployed on wide scale, and provide benefits of treating worm diseases in the farm animals. Additionally, we will engage the community to demonstrate the potential benefits of treating animals with ivermectin to thwart malaria. We will hold small meetings to gain the community, public health workers, and government officials' perspective on this potential control measure. Understanding the community perspective would allow us to develop the most effective ways to expand and achieve compliance with this control measure on Sumba and other areas of Indonesia. There are many Anopheles species on Sumba and we know very little about their feeding preferences for humans or livestock. We will use both human and livestock baited traps to characterize the feeding behavior of Anopheles on Sumba to gain a better understanding about how effective ivermectin treatment of livestock could be if implemented on Sumba. If positive results shown here, then this intervention could be reproduced throughout Indonesia and other areas of the world to eliminate malaria.

Novel vector control tools are urgently needed to combat residual transmission by outdoor feeding malaria vectors, and novel chemistries are needed to manage insecticide resistance. Ivermectin is used widely in human and veterinary medicine to control nematodes and ectoparasites. The blood of ivermectin-treated vertebrates is lethal to Anopheles mosquitoes. Mass ivermectin treatment of livestock (ITL) could interrupt the transmission of malaria, and clear livestock of nematodes improving health, weight gains, and economic benefit to their owners. A recent meta-analysis demonstrated that ownership of livestock increases the risk of malaria in Indonesia. Sumba is one of the most underdeveloped and malaria burdened islands in Indonesia. People on Sumba keep livestock underneath their house at night, potentially increasing their risk of contracting malaria. We propose to treat livestock (cattle and pigs) with ivermectin, capture wild Anopheles after they feed on the animals, and evaluate effect on mosquito survival. Mosquito mortality data will be coupled with blood ivermectin concentrations to assess ivermectin susceptibility of Anopheles species on Sumba. We will engage the surrounding community to demonstrate the potential benefits of ITL to thwart malaria. Small group meetings will be conducted to assess community, public health worker, and government officials' perspective on malaria and this novel vector control tool in order to enhance compliance with ITL. There are at least ten potential Anopheles species incriminated in malaria transmission on Sumba, and very little is known about their feeding preferences. We will use both human and livestock baited traps to characterize the feeding behavior of Anopheles on Sumba to gain a better understanding about how effective ITL could be on Sumba. If effective, then this intervention could be reproduced throughout Indonesia and other areas of the world to eliminate malaria.

The primary beneficiaries of this research, should it someday be implemented on a mass scale for malaria elimination, are the impoverished people afflicted with the scourge of malaria in Indonesia and areas abroad. The burden of malaria traps people in a cycle of poverty due to morbidity and mortality, and subsequent loss of income from dealing with treatment and missed work opportunities. Malaria also leads to cognitive and physical development stunting in childhood and missed time at school which all lead to a reduction in overall societal development and wellbeing in a region. By developing novel methods of malaria control we can minimize this overwhelming burden afflicting some of the worlds poorest persons. Sumba Island is the least economically developed of the large islands in Indonesia, in part due to its' intense malaria burden. Reducing or even eliminating malaria on Sumba would aid all of the points raised above, in addition, allow Sumba to more readily participate in the booming tourism industry in Indonesia, which would help lift its population from poverty. Co-I Claus Bogh directs the Malaria Control and general Health Programs of the Sumba Foundation, an NGO dedicated to improving the health, nutrition and education levels of the Sumbanese, while retaining the cultural identity that makes Sumba such a unique place. The Sumba Foundation operates 5 malaria clinics in rural Sumba and in 2009 opened a Malaria Training Center that has educated more than 450 government technicians and nurses in WHO standard malaria diagnosis.
In addition to malaria reduction, mass ivermectin treatment of livestock (ITL) will dramatically improve domesticated animal health by reducing intestinal helminth and ectoparasitic burdens. Helminths and ectoparasites can reduce livestock weight, diminishing protein yields, in turn reducing the quality of local human diet and economic yields when delivered to market. Thus, rural livestock owners on Sumba and in Indonesia could benefit tremendously from the antiparasitic properties of mass ITL. ITL would clearly have numerous benefits to the community in terms of human and animal health, enhancing overall quality of life and well-being.
By involving the local community, healthcare workers, and district-level politicians on Sumba through our community engagement efforts we will have reached the spectrum of stakeholders that could benefit from this intervention. Claus Bogh works on Sumba and frequently interacts with local, district and provincial level officials regarding malaria eradication on the island. This connection will facilitate direct translation of our research findings to policy level and to promote potential control measures on a mass scale on Sumba. Furthermore, Claus is strongly integrated with the Indonesian National Malaria Control Program through his frequent consultations and invitation to national and regional level meetings. Thus, he will be key to disseminating results from this trial to the appropriate malaria control officials in Indonesia. This will maximize potential uptake and direct effects of our research findings to government officials with the power to enact policy change at local and national levels.