Species Composition of Cockroaches, Their Potential as Mechanical Vectors of Intestinal Parasites and Associated Factors Among Households in Sekota Town, Northeast Ethiopia; A Community-based Cross-sectional Study

Background: Cockroaches pose a signi�cant nuisance, and public health threat due to their ability to transmit pathogenic organisms including intestinal parasites. Due to little attention given to mechanical transmission of parasitic diseases by various vectors, appropriate interventions are not implemented to date.The extent to which cockroaches may harbor parasites is poorly understood in Ethiopia, particularly in the study area. This further overwhelms the already fragile program of prevention and control of parasites. Objectives: To assess species composition of cockroaches, their potential as mechanical vectors of intestinal parasites and associated factors among households in Sekota town, Northeast Ethiopia. Methods: A community-based cross-sectional study was conducted in households found in Sekota town from February to April 2020. A total of 402 households were selected by a systematic random sampling technique. Possible risk factors were collected via a structured questionnaire, and 1750 cockroaches were collected using jars. Species identi�cation of cockroaches was performed using taxonomic keys, and parasite isolation was done using formol-ether and modi�ed modi�ed acid-fast techniques. The data analysis was done using SPSS version 23. P-value of less than 0.05 was considered statistically signi�cant. Results: All cockroaches collected were identi�ed as a species of Blattella germanica (B. germanica). Overall, 63 (36.0%) of the 175 batches were found to harbor intestinal parasites, E. histolytica/dispar (14.3%) and H. nana (8.6%) being the predominant species. About 38 (21.7%), and 49 (28.0%) of cockroaches were found to harbor parasites external parts and gut contents, respectively. Improper latrine

Methods: A community-based cross-sectional study was conducted in households found in Sekota town from February to April 2020. A total of 402 households were selected by a systematic random sampling technique. Possible risk factors were collected via a structured questionnaire, and 1750 cockroaches were collected using jars. Species identi cation of cockroaches was performed using taxonomic keys, and parasite isolation was done using formol-ether and modi ed modi ed acid-fast techniques. The data analysis was done using SPSS version 23. P-value of less than 0.05 was considered statistically signi cant.
Results: All cockroaches collected were identi ed as a species of Blattella germanica (B. germanica). Overall, 63 (36.0%) of the 175 batches were found to harbor intestinal parasites, E. histolytica/dispar (14.3%) and H. nana (8.6%) being the predominant species. About 38 (21.7%), and 49 (28.0%) of cockroaches were found to harbor parasites on external parts and gut contents, respectively. Improper latrine utilization (P=0.006), presence of domestic animals (P=0.032), and presence of parasite-infected child in the household (P=0.001) were signi cantly associated with parasite carriage of cockroaches.
Moreover, houses attached via two or more sides with neighboring houses (P=0.045), houses with cracks on their walls (P=0.001), and households with poor solid waste disposal (P=0.001) were at a signi cantly higher odds of cockroach infestation.
Conclusion: Human and environmental factors have favoured infestation by Blattella germanica in the study area. Therefore, households housing condition, latrine utilization, and waste management systems should be improved.

Background
Cockroaches are the most notorious insects distributed throughout the world and they are inhabiting most human made structures [1]. There are more than 4,400 species of cockroach, of which 30 species are highly synanthropic (adapted to human habitation), thriving in so many habitats and consuming virtually any organic matter [2]. Of these, Periplaneta americana (American cockroach), Blattella germanica (German cockroach) and Blattella orientalis (the Oriental cockroach) are considered the most common pests to people [3]. Majority of these species live in tropical and subtropical areas where they are not recognized as pests. They feed on human faeces as well as human food and they can spread pathogenic bacteria, fungi and parasites in human dwellings [4]. The potential exists therefore, for mechanical transmission through physical dislodgement, regurgitation, or fecal pellet deposition onto and/or into exposed human food [5]. They are also source of potent environmental aeroallergens which provoke allergic reactions especially in children [6].
Cockroaches have an association with human waste and are able to tra c from sewers into homes and are attracted to dark and moist-warmth environment such as toilets, bathrooms, kitchens and basements [7]. Some cockroach species are not only a domiciliary pest but also the most frequent species in sewers which colonize there, and turning in to suitable environment for reproduction and growth [8].
The infestation of cockroaches in the human dwellings is increasing year after year, mainly due to insu cient dumpsites, domestic waste accumulation, poor housing standards, over-crowding and ignorance [9]. Poor environmental sanitation is believed to encourage the spread of cockroaches and sustenance of parasitic infections. Many parsitespecies have been found to be naturally associated with cockroaches.These relationships probably represent incidental associations with the omnivorous feeding behavior of cockroaches (Brenner & Kramer, 2019). Those parasites that are spread by cockroaches can pose serious public health problems in developing countries [10].
The mechanical transmissions of parasitic diseases by cockroaches are neglected. However, cockroaches can be potential reservoirs and possible vectors for intestinal parasites [11][12][13]. Moreover, epidemiological information on species composition of cockroaches, their potential as mechanical vectors of intestinal parasites and associated factors is very limited in Ethiopia. So, this study aimed to assess species composition of cockroaches, their potential as mechanical vectors of intestinal parasites and associated factors among households in Sekota town, Northeast, Ethiopia.

Materials And Methods
Study design, period and area A community based cross-sectional study was conducted from February to April, 2020 among households of Sekota town, Northeast Ethiopia. The area is located 720 km far from the country's capital, Addis Ababa.It has latitude and longitude of (12°38′N39°02′E) and an elevation of 2266 meters above sea level.The town has also an average annual temperature of 29°C, an annual average rainfall of 786 mm and 35% humidity. Humid and hot climate makes the area conducive for cockroaches.

Sample size and sampling technique
A strati ed sampling technique was employed to allocate households to four kebeles (the smallest administrative unit in Ethiopia). Then, the allocated households in each kebele was selected via a systematic random sampling technique. A total of 402 households were included, and cockroaches were collected from the selected households. Insecticide sprayed houses within two weeks prior to cockroach collection were excluded for cockroach collection. During sampling, the trapped cockroaches were labeled and sorted by capture sites in households (living room, kitchen and toilet) and kebele.

Data collection
Questionnaire: A face to face interview and observation was conducted by a trained nurse with the representatives of the households using a structured and pre-tested questionnaire. The questionnaire was used to collect demographic data and risk factors for cockroach infestation such as, housing condition, environmental hygiene and other independent variables.
Collection and identi cation of cockroaches:The cockroaches were collected using empty jars coated with a thin lm of Vaseline baited with a piece of bread soaked in water. The collection jars were put at 19:00 hr and retrieved at 7:00 hr the next morning. The trapped cockroaches were transported in jars to the Tefera Hailu Memorial hospital laboratory for identi cation and parasitological analyses. Then, morphological identi cation of the cockroach species was performed using standard taxonomic keys after they were anaesthetized and killed by exposure to ether [18]. One hundred seventy ve batches of cockroaches (each batch with 10 cockroaches) were processed. External body surfaces and internal (gut) contents of the cockroaches were processed as described by Haile et al to isolate parasite species [17].
Isolation of parasites from cockroach body surface:After species identi cation, each cockroach batch was placed in a tube containing 10 ml of normal saline. The tube was shaken vigorously for two minutes to detach parasite stages from the external body of the cockroaches. Cockroaches were removed from wash solutions using forceps and xed in 90% alcohol. Then, the wash solutions werecentrifuged at 2000rpm for 5minutes. The supernatant was discarded and the sediment was used for formol-ether concentration technique and modi ed acid fast staining [20].
Isolation of parasites from cockroach guts:After external body examination, the cockroaches were xed in 90% ethanol for 5 minutes. Afterwards, cockroaches were washed in saline to remove the traces of alcohol from the body of the cockroaches and allowed to air-dry at room temperature. Then, cockroaches were put on a plate for dissection; the head was severed rst, followed by trimming of the wings and legs, then the abdomen was opened using ne pointed forceps with small scissors and whole gut was removed using needles. After every dissection, instruments were decontaminated to prevent cross contamination by dipping in ethanol between dissections. The excised guts were homogenized in 5 ml of saline solution and the homogenate was ltered through gauze and centrifuged at 2000 rpm for 5 minutes. The supernatant was decanted and the sediment 0.5-1ml processed further using formol-ether concentration technique and modi ed acid fast staining to examine for parasites [21].

Quality assurance
The questionnaire was pre-tested, and the necessary amendements were made before data collection. Training was also given for the data collectors (laboratory technicians and nurses). The principal investigator had strictly supervised the data collection.

Data analysis
The data were entered in to Epi-data version 3.1 and analyze via SPSS version 23 statistical software.
Descriptive statistics and chi-square test was performed. The strength of association between dependent and independent variables was checked via the bivariate analysis. Those variables with P < 0.25 in the binary logistic regression were taken to multiple regression analysis to control potential confounders. P-value< 0.05 was considered as statistically signi cant.

Results
A total of 1,750 cockroaches (175 batches) were collected indoors from three different sites (living room, kitche, and toilet) of the selected households. All the collected cockroaches were identi ed as a species of Blattella germanica. From the total batches of cockroaches, 63 (36.0%) batches were found to harbor atleast one intestinal parasite species. Regarding cockroach collection localities, the highest number of cockroach batches collected and the highest prevalence of intestinal parasites isolated were from kebele 02 and 04, respectively. The highest proportion (52.3%) of intestinal parasites was isolated from cockroaches collected from the toilets (Table 1)

Discussion
Cockroaches are nuisance pests and great concern to public health due to their ability to serve as mechanical vectors of pathogens including parasites [22].Results from this study showed that E. histolytica/dispar (14.3%) was the predominant parasite isolated from cockroaches. It was was lower than the prevalence reported by Bala & Sule (2012) in Nigeria [23]. The predominance of E. histolytica might probably be because of the ability of the cyst to survive days to weeks in the external environment, and henceit can be accessed by cockroaches. Adenusi et al [24], and Oyeyemi et al [25] reported that the presence of E. vermicularis signi es the obvious contact of cockroaches with infected persons in houses or clothing which con rms roaches' ability to transmit different parasites that are responsible for a number of disease conditions in man, some of which could be life-threatening. For example E. histolytica causes amoebiasis, a potentially severe and life threatening disease and the second most common cause of death from parasitic diseases, after malaria. Cryptosporidium spp. and G. lamblia are also nowadays, major causes of diarrhea especially in children [17,22]. Cryptosporidium parvum and Giardia spp. are zoonotic protozoans isolated from cockroaches. This indicates that cockroaches can serve as mechanical vectors of several zoonotic parasites which cause zoonotic disease [24].
In our study the prevalence of intestinal parasites was 28.0% in the gut, and 21.7% 5 on the external body surface of cockroaches. The difference was statistically signi cant (χ2= 176.5, P = 0.001, 95% CI = 0.001, 0.017). It is supported by Hamu et al. (2014), that reported higher rate of parasite isolation in the cockroaches' gut (75.6% in the gut & 10.9 % on external surface). This might be due to the voracious feeding habit of cockroaches that might end up with ingestion of parasites from the fecal material [19]. In contrast, a report by Edwin (2019) showed that 65.3% of total parasites obtained were isolated from the external surface, while gut contents had 34.6% [7].
In this study, overall parasite carriage rate (36.0%) of cockroaches recorded was lower than previous studies in Ethiopia with 75.1-75.6% (17,19), Cameron with 47.39% [22] and Nigeria with 96.4% [24]. However, it was higher than an earlier nding in Palestine with 17.3% [26]. The differences in hygienic conditions, socio-economic status of the people, transmission dynamics, andprevention & control measures taken for intestinal parasites in these various areas might account for the variation.
The highest prevalence of intestinal parasites was isolated from cockroaches collected in toilets (15.4%), while the lowest record was in kitchens (7.4%). The difference was statistically signi cant (χ2= 7.0, P = 0.029, 95% CI = 0.004, 0.053). Alzain (2013) revealed in his study that almost all cockroaches collected from toilets were contaminated with various parasite species which were signi cantly higher in comparison to other sites. Ojianwuna et al also observed that the cockroaches collected from the toilets had more parasites, probably because they are easily exposed to and contaminated by fecal matter [16].
The current study identi ed that houses that are attached by two or more sides with neighboring houses were twice at higher odds of cockroach infestation (AOR=2.0). This nding is supported by a study done in Nigeria [24]. This might be due to cockroaches' tendency to congregate in corners while foraging, and traveling along the edges of walls or other surfaces. Moreover, the odds of cockroach infestation was higher for houses having cracks on their wall (AOR= 4.8). This might be because of cockroaches would love to hide in dark, and warm areas especially narrow spaces. Furthermore, our study indicates that households with poor solid waste disposal were at 5 times higher odds of cockroach infestation than those having good waste disposal systems. Poor environmental sanitation is believed to encourage the spread of cockroaches and sustenance of parasitic infections [10].
In this study, different factors were found to be signi cant predictors of parasite carriage by the cockroaches. Consequently, cockroaches present in households the owned domestic animals were at 2.6 times higher odds of parasite carriage. This is supported by a study done in Cameron [22]. This might be due to the zoonotic nature of some parasites, and animals can also carry parasites on their body from the outdoors bring them to the indoors for easy access by cockroaches. Moreover, cockroach batches collected from households with improper utilization of latrine were at 3.2 times higher odds of harboring parasites. In the same way, the presence of parasite infected child in the household puts cockroaches at higher odds of parasite carriage (AOR= 6.7). This might be partially explained by the fact that the improper human excreta disposal might end up with piles of faecal matter that can attract cockroaches [19,25].

Conclusion
Blattella germanica was found to be the only cockroach species in the study area. A signi cant number of cockroaches also harbored intestinal parasites. Various human and environmental factors have favoured cockroach infestation in the area..Therefore, it is imperative to institute control measures like improving housing condition, utilization of latrine, proper domestic waste management and environmental sanitation in order to minimize cockroach infestation.

Declarations
Ethics approval and consent to participate Ethical approval was obtained from the Ethical review board of College of Medicine and Health Sciences, Bahir Dar University. After the purpose of the study explained to the selected households, informed written consent was obtained from each study participant. All information obtained at each course of the study was kept con dential. The ndings of the study was communicated and oriented for their better management of their house and environment to avoid the cockroaches.

Consent for publication
Consent for publication is not applicable as individual data such as images and videos did not accompany this manuscript.