Human Trichinosis in rural area Mountainous Provinces in Vietnam in 2015-2016

Trichinellosis is an important food borne parasitic zoonosis caused by nematodes in the world. From 1967 to 2013, six outbreaks of trichinellosis have been documented in four mountainous provinces of North Vietnam. This study aims to estimate the magnitude of association of individual factors with current human Trichinellosis in endemic areas. Baseline cross-sectional data collected between May 2015 and June 2016 from a large community randomized-control trial were used. We interviewed a total of 4,362 individuals who provided serum samples to assess ELISA assay to detect anti-Trichinella immunoglobulin G. The association between individual factors and the prevalence of current infection with Trichinellosis was analysis by Stata 12.0. The results obtained suggest that increasing age, being male and consuming pork as well as a larger proportion of roaming pigs, are at higher risk of infection. Furthermore, consuming pork at another village market had the highest increased prevalence odds of current infection. A survey of trichinellosis seroprevalence in these fi ve districts showed the disease to be associated with consuming raw pork (OR=2.84, p<0.05). Seroprevalence was estimated with 95% confi dence and was in the range 0% 10.5%. For control of trichinellosis to be improved, the factors identifi ed as infl uencing its maintenance in the study areas must be communicated to the local administrative organizations and veterinary and public health offi ces. Research Article Human Trichinosis in rural area Mountainous Provinces in Vietnam in 2015-2016 Nguyen Thu Huong1,3*, Nguyen Thi Hong Lien1, Nguyen Thi Hong Ngoc1, Le Thi Hong Hanh2 and Tran Thanh Duong1,3 1National Institute of Malariology, Parasitology and Entomology, Vietnam 2National Hospital of Pediatrics 3FEPT Vietnam Dates: Received: 15 June, 2017; Accepted: 10 July, 2017; Published: 11 July, 2017 *Corresponding author: Nguyen Thu Huong, National Institute of Malariology, Parasitology and Entomology, Vietnam, E-mail:


Introduction
Trichinellosis, a zoonotic disease caused by the ingestion of larvae of Trichinella nematodes, occurs globally and has commonly been reported in Southeast Asia [1]. Trichinosis is a disease caused by the larvae, 'trichinae', of a small nematode worm (Trichinella spiralis), which can affect many species including humans. People can become infected by eating raw, undercooked or processed meat from pigs, wild boar, horses or game that contain the trichinae. The infection commonly causes symptoms such as diarrhoea, abdominal cramps and malaise. It can progress, causing fever, muscle pain and headaches and in severe cases may affect the vital organs possibly leading to meningitis, pneumonia or even death [1,2].
The disease is related to lack of understandings, habit of eating raw or undercooked meat; in additions, slaughtering animals for food not controlled by food safety and hygiene controls or livestock grazing are important factors that help infection of the diseases. Trichinella is found in domesticated animals (mostly pigs) in 43 countries (21,9%) and in wildlife animals in about 66 countries (33,3%) [3]. Human trichinosis is documented in 55 countries (27,8%) in the world [2]. There are reported 8 species of Trichinella (T. spiralis, T. nativa, T. britovi, T. murrelli, T. nelsoni, T. pseudospiralis, T. papure và T. zimbabwensis) and 4 genotypes (T6, T8, T9, T12). All of those species and genotypes are classifi ed into 2 major groups based on whether musclestage larvae is encapsulated or not [1].
In Asia, Trichinella spp. infection has confi rmed in humans in 18 countries, domestic animals (mainly pigs) in 9 countries, and wildlife in 14 countries [4]. T. spiralis has a regional distribution [4] with the majority of outbreaks recorded in the ethnically diverse regions of central and northern Laos, northern Thailand and northwest Vietnam where consumption of uncooked pork is common [5][6][7].
In Vietnam, Trichinella sp. was detected for the fi rst time in 1923 in two (0.04%) of 4,952 pigs tested in Hanoi [8]. Trichinellosis was diagnosed among six soldiers in Saigon, two of whom died, in 1953 [9]. spiralis larvae were detected in free-roaming pigs [10] and the source of infection was a wild pig, rat [11,12] where an outbreak of trichinellosis occurred.

Study area and population
The Cross-sectional study was conducted from May 2015 to

Study design and sampling
The sample size calculation used a seroprevalence of 10% as little prior information was available and was suffi cient to estimate human seroprevalence with 5% precision. In total, 20 clustes were randomly selected (5 clustes in each province) using probability proportional to human population. In each village, 17 households were randomly selected regardless of pig ownership during a village-wide meeting. Within these households, one household member over 6 years of age was randomly selected to be sampled and interviewed, resulting in a total of 4,362 human participants. A questionnaire for humans, Finger blood samples were collected for all participants and to make copies of blood drills in the fi eld. The samples were transferred to the laboratory and then as a 7% staining technique and eosinophil counts [13].
Blood vein samples were collected in plain vacutainers.
Samples were refrigerated and then placed on ice until arrival at the laboratory in NIMPE, where they were stored at -20°C before testing. Human serum samples were tested for the presence of antibodies against T. spiralis using the following commercial diagnostic kits: T. spiralis IgG ELISA (IBL International, Germany and reported sensitivity of 95% and specifi city of 94.8%). Manufacturers' instructions were followed when conducting and interpreting these kits [14]. The positive serum samples with anti-ELISA IgE Trchinella were subjected to Western blot (WB) for confi rmation. Antibodies against T. spiralis antibodies using the Priocheck Trichinella Ab ELISA (Prionics, Switzerland. Sensitivity: 97.1-97.8% and specifi city: 99.5-99.8%) [14], were detected using an protocol as per Maria Angeles Gomez et al. [15].

Statistical analysis
Data management: All questionnaire and serological data were entered into a questionaire survey design and management application. This application was designed with Vietnamese language display features so that entry and data checking could be undertaken by a team member in their native language. Data cleaning and descriptive statistical analysis were conducted in Microsoft Excel. The remainder of statistical analyses were carried out in Stata (v. 12.0). Exploratory data analysis: Seroprevalence of zoonotic pathogens were estimated for humans at the NIMPE and chi-squared tests were performed using the stats package to assess whether seroprevalence in humans seropositive differed signifi cantly between Provinces. Risk factor variables included in the analysis were: water sources, pork consumption and food preparation habits (including consumption of raw pork, herbs, wild vegetables and pigs' blood) and contact with pigs including presence of pigs in the household, involvement in pig husbandry and participation in pig slaughtering. General population characteristics e.g. gender, age occupation and province were included as supplementary variables.
Risk factor analysis: Risk factor analysis was performed to assess whether the participants increased the risk of testing seropositive for T. spiralis pathogens. Village was included as a random effect to control for the correlation of humans within villages. Age and gender were included as fi xed effects to control for potential confounding effects of these variables.
Gender was subsequently removed from any models where it was associated with the outcome with a p-value > 0.05.
Chi-squared tests were used to assess the associations with variables of interest and the pathogens.   and larval penetration of the intestinal wall and a parenteral phase associated with the migration of larvae, via lymphatic and blood vessels, to striated muscles where they encyst in a nurse cell complex. Clinical symptoms in humans are related to the number of viable larvae consumed and are typically associated with the parenteral phase. Humans are a dead-end host and not involved in perpetuating the lifecycle [1].

Discussion
Over the past 30 years, sporadic outbreaks of the disease usually occur at festivals or funerals and the largest reported in 4 provinces: Yen Bai, Thanh Hoa, Dien Bien and Son La with large uspected human cases [10,16]. However, in fact the many outbreaks have so much in the provincial epidemiological community by eating habits and preventive hygiene practices is limited. The fi rst trichinellosis outbreak in Vietnam was reported in 1967 in Mu Cang Chai, Nghia Lo (now Yen Bai province) in the Northern Region [17] and since then outbeaks have been continually documented [18,19]. The continual reporting of cases through the national surveillance system led to Vietnam being named as one of the trichinellosis endemic countries in Asia and Sourthen East Asia [2,10]. The clinical epidemiological surveys carried out from 2010 to 2012 revealed statistically signifi cant associations of myalgia and facial edema with a Trichinella-positive serology (by both ELISA and Western blot) in persons from villages, whereas a statistically signifi cant association of myalgia with a Trichinella-positive serology was observed in persons sampled in hospitals [18]. The high prevalence (1.6-3.5%) of anti-Trichinella IgG in persons from Vietnamese provinces where Trichinella spiralis is circulating in pigs strongly supports the need to develop control programs to eliminate the infection from pigs and for consumers' education and protection [20].
The results suggest that in local study sites, where a trichinellosis outbreak occurred before and neighborhoods this investigation who had eaten raw meat dishes prepared from the same wild boar had trichinellosis. Diagnosis was  [22][23][24]. In Son La have one outbreak with 22 pateints and 2 of them died in 2008 [25]. Epidemiological and risk factors investigations in these two provinces after the epidemic determined that animals (wild boars, synanthropic rats and local-roaming pigs) had Trichinella infection [11,12,26]. The results of this study are also lower than the local epidemiological surveys after the epidemics such as Thanh Hoa 1.7% compared to the survey data in 2012 was 7.4% [27]. Dien Bien 10.5% compared to the survey data in 2013 was 28.5% [28].
In this study, most infected Trichinalle person were age of labor from 16-59 (80.4%), and females was two times higher than males. Other studies reported, the infected patients were adults of the 41-to 50-year-old age group (35.1%). Only one 6-year-old child acquired the infection in the 2012 outbreak.
Males were more infected (84.2%) than females (15.8%) [27]. This difference may be due to the fact that this report is available to patients at the outbreak rather than a large-scale regional survey as this study. The study in Thailand, It is not uncommon to see patients in the 10-14 and 65+ age groups,   share boder with Lao PDR and infection in humans occurs via the ingestion of raw or undercooked meat containing the larvae of T. spiralis nematodes [31][32][33][34][35][36][37][38][39][40][41]. Suspected human cases occur regularly in Vietnam, however, diagnostic facilities and outbreak investigation are lacking [10]. Today in Vietnam, people buy pigs in the mountains transported to the delta and the city slaughtered meat, especially processed foods of this Lap food of ethnicity are also widely disseminated. This does mean the Kinh people, people of the main Vietnamese ethnic group, also acquired the Trichinella infection.

Conclusion
The risk of Trichinella antibody detection in the ES ELISA increased signifi cantly with increasing age and Lao-Tai people were at signifi cantly greater risk Anti-positive Trichinella IgG ELISA rate is high 5.1% (0.0%-10.5%) in the communities The risk of Trichinella antibody detection was associated with sex, age, and certain ethnic groups, suggesting that prevention measures could be targeted toward specifi c populations. Higher prevalence was recorded in the labor age group than other age groups. Trichinosis female ratio two times higher than men.
Prevalence among Thai ethnic group was higher than other ethnic groups.
Risk of Trichinella antibody detection was also associated with specifi c food practices, such as eating raw pork. This suggests that prevention efforts could be targeted toward specifi c food preparation and consumption practices. Lap traditional food is risk factor for Trichinella infection.

Recommendation
Prevention efforts, such as education around safe food handling and preparation practices, should be developed and introduced into the communities identifi ed in this investigation. Further efforts should be made to understand the interactions among human health, animal health and the environment using a One Health approach.