Porcine Cysticercosis Seroprevalence and Potential Transmission Risk Factors in Iringa District Council, Tanzania

Porcine cysticercosis is endemic in Tanzania, especially in the southern, central part and northern highlands of the country. The disease reduces meat quality and affects pig industry. This study investigated porcine cysticercosis prevalence and possible risk factors for reference in preparation for sustainable control measures. Methods Current seroprevalence and potential risk factors were studied in selected ward/villages of Iringa district council, in the southern highland of Tanzania, prior to a digital health education intervention. A total of 346 pigs from 88 households of Izazi, Migoli and Mlowa wards were studied using an enzyme-linked immunosorbent assay (ELISA), which detects Taenia species antigens (Ag) in sera. Questionnaire used to dig information on pig management and sanitation and hygiene practices. = Prevalence; *signicant difference between positive and negative risk factor status during a study to estimate porcine cysticercosis prevalence


Introduction
The population of pigs in Tanzania is around 2 million, mostly kept under small scale production or as a farmyard activity (Michael et al., 2018). This population was estimated to be kept by 22.4% agricultural households (Kimbiet al., 2015) of both in rural and urban areas. Pig farming contributes to more than a quarter of rural livelihood and with a contribution to urban community livelihood. Globally, pig production has shown an increasing trend in developing countries, reaching 60% of the world pig production by 2020 (Zhang et al., 2012). Despite the on-going pig production efforts, the pig business encounters various constraints, including diseases (McGlone, 2013). Porcine cysticercosis is one of the diseases that hinder production by reducing meat quality (Mkupasi et al., 2013). The disease is caused by a zoonotic parasite Taenia solium that also causes taeniosis and cysticercosis, worse neurocysticercosis in humans (Winkler, 2012). Cysticercosis causes up to 30% epilepsy cases in humans in endemic areas (WHO, 2020).
Porcine cysticercosis is common in developing countries with sub-standard pig rearing systems (Blocher and Auer, 2011). In Tanzania, the disease prevalence ranges between 1.5-33.3% based on different studies by antigen ELISA test conducted previously . The highest prevalence has been reported in Iringa, Mbeya, and Ruvuma regions in the southern highlands that contribute to about 54% of Tanzania pigs production (Kimbi et al., 2015). Some studies in Tanzania have associated porcine cysticercosis with free-range pig rearing systems, lacking household latrine, drinking water form rivers and ponds, feeding pigs peels from tuber foods and any possible environmental contamination with Taenia solium eggs .
Education on construction of modern pig housing with locally available resources, improved pig feeding and environmental sanitation and hygiene were recommended as important Taenia solium control strategies in Tanzania  Community education through digital health education found to hasten knowledge transfer and effective diseases control worldwide (Ren et al., 2015). The Vicious Worm Educational Tool (VWET) was reported to be effective digital health education in Taenia solium zoonoses knowledge transfer among health and agricultural professionals in Mbeya region, Tanzania (Lauridsen et al., 2019). Efforts of digital health education based on cysticercosis control among smaholder pig-farmers in Iringa District Council , has created interest in investigating for the current porcine cysticercosis prevalence and possible risk factors to be references in the digital health education success.
This article reports the present porcine cysticercosis prevalence and potential transmission risk factors to set a baseline for determining the digital health education intervention effect.

Study area
This study was conducted in Iringa Rural District in southern highlands of Tanzania. The district occupies 20,576 km 2 lying at 1600-2700 m above the main sea level and the estimated population was 254,032 (NBS, 2012). Average low temperature mostly is below 15°C and rainfall of up to 175 mm per year. The rain season is from November to May with a peak in January (World Weather Forecast, 2019). Pigs in this area are predominantly kept on small scale farms. Iringa district was estimated to have 14.5% of the total pigs found in Iringa region that comprises ve districts (NBS, 2012). The study was carried in nine villages that belong to three wards (Izazi, Migoli and Mlowa) (Fig. 1). The studied area was previously reported to have porcine cysticercosis prevalence of 7.5% by lingual palpation method (Yohana et al., 2013) and human taeniosis incidences in neighbouring regions (Mwanjali et al., 2013). Also the area was targeted for a community based digital health education intervention by providing the communities with free internet access and a digital health education platform, including porcine cysticercosis educational content . Izazi and Migoli wards were selected for the digital health education while Mlowa ward would serve as a control. The present study is a baseline assessment of porcine cysticercosis and potential risk .

Study design
The cross-sectional study was conducted between March and May, 2019, during the rainy season.
Households were visited once during data collection period for interviews and pig blood samples.

Sample size and sampling
The number of pigs to be studied was estimated using the formula: n = Z²PQ/L² where: n is the number of pigs to be examined and Z is a score for a con dence level. P is a known or estimated prevalence of the factor in the study area, Q is 1-P, a proportion free of the factor and L is an acceptable estimation error (Martin et al., 1987). In this study Z was 1.96, calculated at 95% con dence level. P was estimated cysticercosis infected pigs in population (33% or 0.33) and Q was the proportion of pigs not infected with cysticercosis (1-0.33). L was the estimated error of the study (5% or 0.05). Thus a total of 339 pigs was required.
We aimed at sampling all eligible pigs in each selected household. Based on ward o ce records, one pig keeper had four pigs on average. Therefore, we included a random sample of 100 pig keeping households to achieve our sample size. The random sampling was done in Microsoft Excel worksheet with o cial list of 423 known pig keeping households. Out of the 100 selected households, 88 (88%) agreed to participate. These households had a total of 346 eligible pigs, hence more than the calculted sample size of 339 pigs, and enough to the required sample size. Reasons for non-participation of some households were; refusal by a spouse (n = 7) or unexplained no-show despite several attempts of phone calls and home visits (n = 5).

Pig blood sample collection
Prior to sampling, we used a checklist to obtain a brief animal history from the respondents, including the animal age and likelihood of pregnancy in females. Only animals above 2 months of age and for female pigs observed or informed not pregnant, were blood sampled. Piglets below 2 months and pregnant sows were excluded to avoid stressing that could lead to adverse effects. A pig was restrained using a pig snare and about 5 ml of blood was collected through external jugular vein puncture into a plain vacutainer tube (Swindle, 2010). The collected blood sample was immediately stored in a cool box in an upright position. Then samples were transported to the mini-laboratory at Migoli ward dispensary for centrifugation and serum harvest. Harvested serum sample were kept in 2ml cryogenic tube per pig and temporarily stored at -20 0 C in Migoli temporarily before they were transported to Sokoine University of Agriculture for further storage and analysis.

Questionnaire and observational data collection
A structured questionnaire was prepared in English and translated to Swahili. It was administered by face-to-face interview to respondents in the study households. For each study household a family head or adult representative was interviewed. The basic information collected included; duration and experience in pig rearing, reasons for an adopted pig rearing system and the purpose of keeping pigs. Upon permission from the household head or representative, a researcher examined the household latrines and pig pen through direct observations based on quality parameters described elsewhere (FAO 2009;FAO 2010). The latrine and pig pen quality were scored according to a scaled evaluation chart.

Analysis for porcine cysticercosis seroconversion
Sample analysis was conducted at the CYSTINET-Africa laboratory in the College of Veterinary Medicine and Biomedical Sciences, Sokoine University of Agriculture, Morogoro Tanzania, approximately 407.1 km from the study area. Frozen serum samples were thawn at room temperature for 30 min, analysed for Taenia solium antigens using Enzyme-Linked Immunosorbent Assay (ELISA) and interpreted as per manufacturer's instructions (apDia, Belgium). Antigen index ≤ 0.8 was considered negative, antigen index ≥ 1.3 was considered positive readings, while values greater than 0.8 and less than 1.3 were judged as doubtful results and re-analysed.

Data analysis
Each completed questionnaire transcript was assigned an identi cation code and its data entered into a Microsoft Excel spreadsheet together with its pig data for analysis. The frequency and distribution of cysticercosis positive samples were generated in the same program. The association of the disease prevalence and household factors were analysed using regression analysis in the Statistical Package for Social Sciences (SPSS) version 20 of Armonk in New York.

General results
The 88 surveyed households, the 346 studied animals and 75 pig pens presented in Table 1. A total of 13 households were practising totally free range pigs keeping, they had no pig pens. Pig pens statuses in the three studied wards presented in Table 2. Of which Izazi ward had few number of pigs kept in pig-pen and farmers were having only old made pig-pen.

Risk factors associated with the prevalence of porcine cysticercosis
This study revealed risk factors that were associated with porcine cysticercosis seroprevalence Signi cantly higher seroprevalence was found in scavenging than con ned pigs (OR = 2.426; 95 % CI = 1.202-5.300; p = 0.026) ( Table 4). Also pigs raised in low-quality pens were at risk of being infected compared to those raised in good-quality pens (OR = 1.747; 95 % CI = 1.021-2.989; p = 0.042). The poor pigpens were characterised with weak walls, rough and wet muddy oor. These poor pigpens were lacking drinking water supply, shade and enough space to accommodate the existing number of pigs. The latrine quality factor had nothing signi cant to do with cysticercosis seroprevalence, and disease prevalence was not associated with irregular latrine use. Taenia species eggs, signi es open defecation is practised in community. Also it was revealed that community practices related to sociocultural settings and lifestyles was concerned with the Taenia solium epidermiology (Kajuna et all., 2021). Therefore in this study, more than half of the studied households had at least one potentially infected pig. Indicating the common animal feed sources were prone to contamination, may be during the time of feeds collection by individual from different locations. Most studied free roaming pigs had no shelters, making them highly vulnerable to infection in contaminated environments. Lacking or having poor pig pen could be attributed with porvety and ignorance of using locally available resources for pig management. Possible unallocation of budgets for pig feeding, housing and veterinary services characterises the most traditional small scale pig production , have reported signi cantly high prevalence of porcine cysticercosis in areas lacking latrines. Pigs become exposed to Taenia solium eggs either by feeding on contaminated feeds or faeces from infested human. In the current study, household latrines were common, but latrine quality varied greatly. Surprisingly, latrine quality was not signi cantly associated with porcine cysticercosis disease prevalence. In the present study, community latrines were xed with empty locally made handwashing facilities that were claimed to be for showing to public health inspectors when they visited households for inspection. Not washing hands after using the toilet predisposes community to cysticercosis, since Taenia solium carrier may spread worm eggs through contaminated hands (Winkler, 2012). Heath education improved the smallholder pig farmers' knowledge and attitudes towards Taenia solium control based on a previous study in Tanzania (Ngowi et al., 2011). Therefore community training and sensitization on safety latrine may promote latrine ownership and regular use in the community. The present study acknowledge community needs of sustainable health education on pig management, sanitation, hygiene and safety pork consumption for control of Taenia solium infection and other hygiene and meat borned diseases. Digital health education is presumed to enhance dissemination of knowledge that persist in community (Lauridsen et al., 2019) since it facilitates learning by unlimited training time and easy access to learning material (Gilman et al., 2012). With internet access, more people can access online digital health education.

Conclusion And Recommendation
Iringa District Council in Tanzania was still endemic for porcine cysticercosis after some years of no further studies on the subject matter. Pigs were traditionally produced; commonly in free range system making them prone to porcine cysticercosis infection. Farmers' training on proper and practical pig management is of importance, taking advantage of available local resources. It is important to design and evaluate effective and sustainable ways to train the local communities on Taenia solium.

Study limitations
Ag-ELISA test for porcine cysticercosis is only 82.7 % sensitive and 86.3% speci c (Kabululu et al., 2020). Thus a few false positive or false negative results should be expected. In pigs, the assay test may crossreact with Taenia hydatigena and Taenia asiatica if the pig is infected with these Taenia species. Fortunately, Taenia asiatica has not been found in Tanzania to date. Thus the major concern at the moment is Taenia hydatigena and Taenia solium. In Tanzania were consented for participation. An identity number was assigned to each household instead of names, for con dentiality and data protection. Permission to carry out the study was also provided by the district, ward and village authorities of Iringa

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. Appendix1.docx