Pekalongan residents clean the environment from potential mosquito breeding places to reduce the risk of spreading filariasis. Expert say one health approach is needed to overcome further spread.
Nurul Huda (50), is a resident of Jenggot Village, Pekalongan City, Central Java, Indonesia. One Friday every month, he leaves his house with a hoe and sickle. On these occasions, he is scheduled to work together with the rest of the residents in the village to clear potential mosquito breeding areas in their vicinity.
“The residents work together to clean the environment, which is a routine activity that we carry out once a month every Friday. We clean places that have the potential to become mosquito breeding grounds,” said Huda, the head of the community (RT) in Jenggot Village. He and his neighbors are vigilant in their efforts because Jenggot Village is one of the twelve villages with filariasis or elephantiasis endemic in Pekalongan City.
Lymphatic filariasis, commonly known as elephantiasis, is one of the neglected tropical diseases in Indonesia, apart from leprosy, schistosomiasis and visceral leishmaniasis).
The Minister of Health outlines that filariasis is a chronic infectious disease caused by filarial worms that infect the lymph nodes. Filariasis may damage the lymphatic system, causing a swelling of the hands, feet, mammary gland, and scrotum. Therefore, causing a lifelong disability.
Pekalongan City is one of nine filariasis endemic regencies/cities in Central Java Province. Since it was discovered from 2004 to 2020, there were 455 clinical cases and 41 chronic cases of filariasis in Pekalongan City. Based on the Regulation of the Minister of Health of the Republic of Indonesia Number 94 of 2014 concerning the Prevention of Filariasis, regencies/cities are declared endemic for filariasis if the microfilariae rate in the area is 1 % or more.
Slamet Budiyanto, The Head of the Pekalongan City Health Office said, a person can be infected with filariasis if they are bitten by an infective mosquito, which is a mosquito that contains stage three (L3) larvae. “Mosquitoes are infected with microfilariae by ingesting blood when biting an infected host,” he said.
The World Health Organisation (WHO) described filariasis as a vector-borne zoonotic disease. A zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans. Zoonotic pathogens maybe bacterial, viral or parasitic, or may involve unconventional agents and can spread to humans through direct contact or through food, water or the environment.
Lymphatic filariasis is caused by infection with parasites classified as nematodes (roundworms) of the family Filariodidea. WHO states that there are three types of filarial worms cause filariasis: Wuchereria bancrofti, Brugia malayi, and Brugia timori. Infection occurs when filarial parasites are transmitted to humans through mosquitoes, which act as vector.
Already a clear and present risk, with climate change, the number of mosquitoes is expected to increase-and with it, the incidence of this zoonotic disease.
A changing climate brings increased risk
Climate change is one of the environmental factors that affect public health. Climate change can potentially increase the transmission of vector-borne diseases because it is related to temperature, humidity, and rainfall-all of which affect mosquito populations.
Several studies suggest that climate change can potentially increase the transmission of mosquito-borne diseases such as filariasis. One such study was conducted by Sudarso from the Department of Public Health Sciences, Faculty of Medicine, Wijaya Kusuma University, Surabaya. The study entitled “Climate Change and Its Effect on Increasing Health Problems” was published in the Damianus Journal of Medicine in February 2010.
The results found that climate change, such as the increase in the earth’s average surface temperature that affects the rainfall and humidity levels can also affects the outbreak of vector-borne diseases.
“The increase in earth’s average surface temperature until the year 2100 has consequences for increasing the transmission of vector-borne diseases. Mosquitoes are vectors that cause many diseases in Indonesia, especially malaria, dengue fever, and filariasis,” he explained.
According to Sudarso, mosquitoes quickly adapt to climate change. Mosquitoes can spread widely and reproduce relatively quickly, especially in newly suitable areas (active dispersal). In addition, mosquitoes can spread and often through human transportation, including between continents, such as Aedes albopictus, which can spread via rubber wheels in cars (passive transmission).
Risqa Novita, a researcher from The Research and Development Center for Biomedical and Basic Health Technology, Indonesian Ministry of Health, conveyed the same thing in her research entitled “The Impact of Climate Change on the Emergence of Mosquito Vector-Borne Diseases, mainly Lymphatic Filariasis”. This research was published in the Journal of Health Epidemiology and Communicable Diseases in June 2019.
This study found that climate change affects the mosquito life cycle and the intensity of mosquito bites. This is because mosquitoes are ectothermic, which means their body temperature depends on the ambient temperature.
“The increase in temperature will accelerate the process of developing mosquito larvae into adults. Climate change will also accelerate adult female mosquitoes to digest the sucked blood so that the intensity of the bites will be higher. This increases the frequency of disease transmission,” she explained.
Risqa explained that the current climate change can increase filariasis cases because mosquitoes potentially identified as filariasis vectors belong to four different genera, such as Aedes, Culex, Anopheles, and Mansonia. “Climate change has an impact on rising sea levels, which can increase water salinity. Mosquitoes, such as Aedes sp and Anopheles sp, are tolerant of saline water,” she continued.
Another type of mosquito that can be affected by climate change is Culex sp. According to her, the breeding of Culex sp increased along with increased water temperature. High temperatures in urban areas spur the mosquito breeding season by increasing the reproductive cycle, extending the mosquito breeding season, and interacting with the host. This will serve to accelerate disease outbreaks.
For now, residents continue to take what measures they can to control mosquito populations. Working together to clean the environment is one of the community-led efforts to protect the residents from filariasis transmission.
Thanks to the cadre of health workers from the community health center, Huda and his neighbors know it is necessary to eradicates mosquito breeding grounds to keep filariasis in check. They have been doing so since 2015, when public learned that Jenggot Villages is a filariasis endemic village and Huda was the head of the community.
The community’s efforts are grounded in science. According to Tri Yunis Miko Wahyono, an epidemiologist from the University of Indonesia, it is necessary to break the filariasis chain of transmission and improve the environment apart from mass drugs administration (MDA) for filariasis elimination, especially given the heightened risk with warming temperatures.
“Get rid of the mosquito nest inside and around the house. Waste must be handled properly. Remove standing water where mosquitoes could lay eggs because standing water has arguably become the breeding ground for a mosquito, which can increase the mosquitoes population,” said Wahyono.
According to Wahyono, mosquitoes are estimated to increase 20 folds due to climate change. Thus, he said, the community plays a role in cleaning up their environment to prevent mosquitoes from multiplyng. “If there is no improvement in the environment, with the number of mosquitoes increasing and mosquitoes breed, it can increase the transmission of filariasis,” he added.
Risqa further said that to prevent the increasing number of filariasis cases due to climate change, it is imperative that people develop a healthy lifestyle and the 3M – menguras, menutup dan mengubur – or drain, cover and bury movement, to get rid of any potential breeding ground for mosquitoes, just as Huda and his network have adopted. These measures include draining bathtubs, closing water reservoirs, and burying used items that have the potential to become breeding grounds for mosquitoes intermediary of the filariasis.
One Health approach
The mass drugs administration for filariasis is a simultaneous administration of drugs to all target populations (aged 2 years to 70 years) in filariasis endemic areas. The mass drugs administration for filariasis aims to interrupt transmission by sending a combination of drugs for the entire population at risk of developing filariasis. Furthermore, it’s to manage morbidity and prevent disability.
In 2021, as many as 201,253 residents in Pekalongan City were targeted for MDA for filariasis. People aged 5 years-70 years received three types of drugs, ivermectin, diethylcarbamazine citrate (DEC) and albendazole. Meanwhile, toddlers (aged 2 years-4 years) received DEC and albendazole. The budget allocated for the implementation of MDA in 2021 is IDR 861,607 million.
But that alone is not enough. To overcome this disease requires strong multi-sectoral collaboration with a one health approach from various related fields such as animal health, public health and environmental health.
One health is a communication, collaborative, multi-sectoral and trans-disciplinary coordination approach with the aim of achieving optimal health outcomes by recognizing the interconnections between humans, animals, plants, and the environment together.
“Mosquito control and mosquito-borne control are efforts with the concept of One Health. The concept is an integrated health between human health, environmental health, flora health, and fauna health,” says Indonesian Minister of Health, Budi Gunadi Sadikin.
Meanwhile, in the book entitled “Lymphatic Filariasis: a Handbook of Practical Entomology for National Lymphatic Filariasis Elimination Programmes” published by WHO in 2013, it is explained that vector control can play a significant role in eliminating filariasis.
Filariasis is transmitted when mosquitoes are infected with microfilariae by ingesting blood when biting an infected host. Transmission can be interrupted by killing adult worms, killing microfilariae, killing mosquito vectors, or preventing them from biting humans.
Vector control may play a complementary role in eliminating lymphatic filariasis in two stages. Firstly, during mass drug administration. Vector control will complement reductions in the density and prevalence of microfilariae by actively reducing transmission by mosquitoes. Secondly, during surveillance, by preventing recurrence or new infections after transmission has been interrupted.
WHO mentions several vector control methods for filariasis elimination that can reduce filariasis transmission by disrupting the stages of the mosquito life cycle, including spraying residue indoors. In addition, people can use protection at homes, such as curtains, wall coverings, and household insecticides.
Slamet Budiyanto said, in addition to the mass drugs administration for filariasis, The Pekalongan City Health Office also carried out mosquito fogging for vector control. Fogging was carried out in filariasis endemic villages. According to him, the mosquito fogging will not harm humans.
“Fogging is done before and after implementing the mass drugs administration for filariasis. The mass drugs administration is to kill worms in the human body, while fogging is done to kill vectors that transmit filariasis,” he explained.