The existence and characteristics of rats and shrews in endemic leptospirosis areas and types of ectoparasites: a case study of West Jakarta, Indonesia

Introduction

Rodents such as rats and shrews can carry various bacteria and viruses that can cause infections in humans. They are thought to be a reservoir of 30% of zoonotic pathogens, including several viruses, bacteria, and parasites. Rats are one of the most important components of an ecosystem. Their presence is very widespread, representing 40% of all mammal species (Churakov et al., 2010). They can be useful as food for some mammals and predatory birds (Tobin & Fall, n.d.), but their presence in the ecosystem can cause various losses in sectors such as agriculture and health (Tobin & Fall, n.d.). Rats are a reservoir of various diseases, and as animals that cannot be separated from human life, they can cause various health problems in humans and pets and other wildlife (Tobin & Fall, n.d.). They are also an important host for ectoparasites and have a close relationship, such as lice, fleas, and mites (Kiffner, Vor, Hagedorn, Niedrig, & Rühe, 2011). They can produce a variety of associations influenced by the host and parasite species and the biotic and abiotic environment (Buchholz & Dick, 2017). The rate of rat ectoparasite infestation can reach 66.6%, and ectoparasites are vectors for various diseases which can cause health problems (Zendehfili, Zahirnia, Maghsood, Khanjani, & Fallah, 2015).

Leptospirosis can cause death, with the case fatality rate in humans of 5-30% (CDC, 2018). It is a disease caused by Leptospira bacteria (World Health Organization, 2003). Leptospira interrogans and Leptospira borgpetersenni are present in many populations of rats and have been confirmed to cause leptospirosis in humans (Cosson et al., 2014). The disease can be transmitted through water or soil contaminated by the urine of rats infected with Leptospira bacteria and direct contact with infected animals (Centers for Disease Control and Prevention, 2018; Haddis, 2004; World Health Organization, 2003). Leptospira bacteria can enter the human body through mucous membranes, wounds, or blisters on the skin (Centers for Disease Control and Prevention, 2018; Haddis, 2004; World Health Organization, 2003). In several previous studies, it has been found that Rattus norvegicus is the rat species that is the main reservoir of Leptospira bacteria (Marcos Tucunduva de Faria et al., 2013; Pui, Bilung, Apun, & Su’ut, 2017).

Environmental conditions and their habitat greatly influence the presence of rats; each species has a different habitat. Mus musculus is a rat species that like to live in homes, outbuildings, and shops (Global Invasive Species Database, 2015). Rattus rattus is spread in forests and can also live in and around buildings, both underground and above ground (Csurhes, 2012). Rattus norvegicus is a species that is widespread in places such as sewers, agricultural and horticultural land, grasslands, and the interior part of the region (Hausser & de Roguin, 1995). The rat population will continue to increase to the level of capacity accommodated by their habitat (Jackson, 1972). Moreover, the rat population will also greatly depend on the availability of food and predators' presence in their habitat.

West Jakarta is one of the five administrative cities in the Special Capital Region of Jakarta, Indonesia; its center is in Kembangan. West Jakarta has an area of 129.54 km² and eight subdistricts, namely Taman Sari, Tambora, Kembangan, Kalideres, Cengkareng, Palmerah, Kebun Jeruk, and Grogol Petamburan Districts (Badan Pusat Statistik Administrasi Jakarta Barat, 2019). West Jakarta is one of the areas with 70 cases from January 2016 to August 2019 (Suku Dinas Kesehatan Jakarta Barat, 2019). The population density in West Jakarta in 2018 was 19,757 inhabitants/km², with an average population per household of four (Badan Pusat Statistik Administrasi Jakarta Barat, 2019). This means that West Jakarta is a densely populated area, one of the conditions that rats highly favor. This research aims to establish the presence and species of the rats and shrews that can potentially cause leptospirosis in West Jakarta and the species of ectoparasite found in them. The research could be used as the basis for an early alert system for various diseases that rats can carry, and also as a preliminary study to ascertain which rat species are the main reservoirs of leptospirosis in West Jakarta.

Methods

Results

Based on the results of the study, it was found that more rats were caught in Cengkareng Timur sub-district, Cengkareng District, with a percentage of 14.8% of the total (Table 1) (Susanna, Nova & Rozek, 2021). Based on the result, it can be seen that the rat species most commonly found in the West Jakarta area was Rattus rattus (74.1%), Rattus norvegicus (14.8), Suncus murinus (11.1%), and more male rats were caught, equal to 66.7% (female 33.3%) (Table 2). The only type of ectoparasite found in the rats in the West Jakarta area was the flea (Table 3). Xenopshilla cheopis was the most common type (83.3%) and Xenopsylla astia (16.7%). More fleas were male (66.7%) than female (33.3%).

Discussion

Cengkareng district is the administrative area of West Jakarta with the highest population, comprising 514,416 people (Badan Pusat Statistik Kota Jakarta Barat, 2019). It has 26.54 km² and includes six sub-Districts; Cengkareng Timur sub-District is one of the densely populated areas in Cengkareng district (Badan Pusat Statistik Kota Jakarta Barat, 2019). Based on the research results, rats are most commonly found in the East Cengkareng sub-District. This study found different results to previous studies, which found that rats were more commonly found in agricultural areas (58.0%) (Munõz-Zanzi, Mason, Encina, Gonzalez, & Berg, 2014). These different results could be caused by regional differences and the categories of the research areas. Previous studies [25] have researched three locations, namely agricultural areas, rural areas, and slums, while this study was only conducted in West Jakarta, without categorizing the area.

The presence of rats in an area depends on ecology, vegetation, food availability, and predators' presence. Also, the presence of rats also correlates with the number of tree species; their number will tend to increase in areas with high tree diversity (Madden et al., 2019). However, in this study, the level of tree diversity did not affect rats' presence, as the habitat of those caught was in homes and gutters. Moreover, Cengkareng Timur sub-district is not an area that has a diversity of trees. Seasons also have an important influence on rats' presence; house or commensal rats will be more common in the dry season (Panti-May, Hernández-Betancourt, Ruíz-Piña, & Medina-Peralta, 2012). In this study, the rats were found in densely populated areas, and the process of catching them took place in the dry season so that more would be caught. In the dry season, the availability of rat food is higher, especially leftovers from processed household products, as well as from some home industries in the Eastern Cengkareng sub-district.

In this study, the rat species most commonly found was Rattus rattus (black rats). This species was commonly found because catching the rats and setting traps was commonly found in participants' homes. Rattus rattus is a species whose habitat is forests and homes (Csurhes, 2012). The species can also be found in natural and semi-natural habitats (The ICUN Red List, 2017). It is an arboreal animal that can climb. Rattus rattus favors lowlands that are less than 250 meters above sea level (Isnaini, 2008). The environmental conditions greatly affect the presence of Rattus rattus in the ecosystem, for example, the availability of food sources. Food, organic waste that is not stored or properly disposed of, gardens that are not well managed; and the presence of pets and livestock can affect the number of rats, including the Rattus rattus species (Feng & Himsworth, 2014).

The presence of rats in the community environment can cause various health problems, one of which is leptospirosis, a disease caused by Leptospira bacteria (Centers for Disease Control and Prevention, 2018; Haake, David A, & Levett, 2015; World Health Organization, 2003). Rats are the most important reservoir of Leptospira bacteria. Previous studies have found a similarity between the PFGE pattern and gyrB sequence in Leptospira bacteria isolated from humans and rats in Luzon, Philippines (Villanueva et al., 2014). This indicates that rats infected with Leptospira bacteria can cause leptospirosis in humans (Villanueva et al., 2014). The prevalence rate of Leptospira bacteria in each rat species is different. Based on the results of previous studies, it is known that Leptospira spp positively infects up to 17.8% of the Rattus rattus species., 30.3% of the Rattus norvegicus species, 10.9% of the Rattus exulans species, 19.3% of the Rattus argentiventer species, and 3.4% of the Rattus tanezumi species (Id, Shiokawa, & Id, 2019; Koizumi et al., 2009). From these results, it is clear that Rattus norvegicus is the most infected species with the Leptospira bacteria, which causes leptospirosis in humans. However, to establish which species of rats are most responsible for carrying Leptospira bacteria and causing leptospirosis, further research is needed.

In addition to the presence of rats, ectoparasites can also cause other health problems for humans. One disease that can be caused by rat ectoparasites (fleas) is pes (plague) (Illinois Department of Public Health, n.d.; Nurisa, 2005). Based on the study findings, out of the 27 rats caught, some had ectoparasites such as fleas. The most common type of flea was Xenopsylla cheopis (male). The results of this study are in line with those of previous study by Maulana et al., which also found that several species of rats carried ectoparasites, with the most commonly found type being Xenopsylla cheopis (81.1%) (D, 2012). In another study by Kia et al, it was also found that one of several fleas found in Rattus rattus and Rattus norvegicus was related to the transmission of plague. The most abundant ectoparasite (88.7%) in Bandar Abbas, Southern Iran, was Xenopsylla, found in Rattus norvegicus (Kia et al., 2009).

A previous study by Ristiyanto et al. had also found that female Rattus tanezumi had more ectoparasites than males, while more ectoparasites were in male Rattus exulans rats than in female ones (Ristiyanto, Mulyono, Agustina, Yuliadi, & Muhidin, 2011). Riyanto also found that the most common type of flea found in house rats was Xenopsylla cheopis. This suggests the potential for disease caused by rats and their ectoparasites (Riyanto, 2019). However, not all rats will have ectoparasites, as many aspects can influence their presence. One aspect that can affect the presence of ectoparasites in rats is the season. In the summer, due to dry and hot weather, rats and ectoparasites' presence is low (Alahmed & Al-Dawood, 2001). The presence of rat ectoparasites that can potentially cause health problems leading to high mortality and morbidity must be controlled properly.

Conclusion

Rats were mostly found in Cengkareng district, specifically in the East Cengkareng Sub-District, one of the districts with a high incidence of leptospirosis in West Jakarta. The most common rat species is Rattus rattus. The ectoparasite most commonly found in rats is the male flea Xenopsylla cheopis. Surveys, monitoring, and control of rats and ectoparasites are essential for the preparedness and development of an early warning system of possible diseases that they can cause. Future research should include data about the relative abundance index of trapping, a map of the trapped area, and information about the house/region.

Data availability