Two trichinellosis outbreaks in Serbia - challenging diagnosis due to a potential co-infection with Toxocara spp.

In Serbia, in most cases, small family outbreaks of trichinellosis occur due to the consumption of untested infected meat from domestic pigs that are raised and slaughtered in the backyards of small individual farms. The aim of this study is to present data regarding 24 patients involved in two outbreaks that occurred in two neighbouring districts in Serbia during a closely related period of time in August 2014. The source of infection in the first outbreak was undercooked pork, while raw pork sausages caused the second outbreak. Meat samples and sausages were Trichinella spp. positive by artificial digestion. With the aim to obtain a second opinion and validate the serological findings discovered at the Public Health Institute Nis, all samples were sent to the National Reference Laboratory for Trichinellosis, INEP. Serodiagnosis showed that 21 persons were positive (87.5%) and three (12.5%) were negative for anti-Trichinella antibodies, while 15 patients fulfilled the trichinellosis case definition. Western blot analysis (using an epitope unique for the muscle larvae stage of the Trichinella genus) confirmed the diagnosis of trichinellosis in five patients. Six patients also had specific antibodies against Toxocara canis (T. canis). Due to the fact that in endemic foci in Serbia there is the presence of Trichinella spiralis and T. canis and that these two infections could be asymptomatic, we consider that trichinellosis cases were irrefutably proven. The dilemma about the existence of co-infection with T. canis remained open due to the lack of clinical findings.

Long lasting immunity in trichinellosis - insight from a small study group.

Trichinellosis in humans is most often caused by the parasite Trichinella spiralis. The clinical course of the disease is diverse and the symptoms can vary from mild to severe. Symptoms usually disappear within a few months, but encysted larvae in the muscles can cause myalgia and weakness that last for years. However, the existence of chronic trichinellosis as a disease is still debatable. This study presents the results obtained at the National Reference Laboratory for Trichinellosis - INEP, Serbia. The study was conducted to assess the immunoserological, biochemical and symptomatic disease parameters of twelve patients who acquired trichinellosis 13 and 18 years ago, respectively. They were involved in two T. spiralis outbreaks in Serbia, at the village of Kumane and the city of Belgrade (nine and three patients, respectively). Results indicated the presence of specific anti-Trichinella antibodies in 83% of the total number of patients. However, while the humoral immune response to Trichinella lasted for more than a decade reaching almost two decades after the acute infection phase (7/9 and 3/3 respectively, in two outbreaks), persistence of chronic muscular pain, as the most prolonged symptom of trichinellosis, could be found in the majority of patients from the Kumane outbreak (7/9). As a consequence, these patients suffered from limitations in daily living activities for the same period of time. The results presented in this paper are our contribution to the view that trichinellosis as a chronic disease with symptoms exists and may be related to the severity of the disease in the acute phase.

Trichinella britovi outbreak: Epidemiological, clinical, and biological features.

OBJECTIVES: We aimed to describe the first cases of human trichinellosis due to Trichinella britovi in Serbia. A large trichinellosis outbreak due to the consumption of wild boar meat products took place during the 2015-2016 winter. PATIENTS AND METHODS: In January 2016, the Department of Infectious Diseases in Uzice examined 111 individuals with clinical and biological signs of trichinellosis, of whom 19 were hospitalized. Trichinella species identification was performed by multiplex PCR. Serodiagnosis was performed using immunofluorescence antibody assay, indirect ELISA, and Western Blot as confirmatory tests. RESULTS: The main symptoms included myalgia (83%), weakness (82%), joint pain (80%), fever (77%), facial edema (74%), and diarrhea (23%). Eosinophil levels>500/µl were observed in 98% of patients. Elevated CPK levels were detected in 71% of patients and elevated LDH levels in 75%. Three patients had cardiac complications. Treatment included mebendazole, nonsteroidal anti-inflammatory drugs, and corticosteroids. Anti-Trichinella antibodies were observed in 89.7% of patients two months after disease onset, including all hospital-treated patients. Among them, serum positivity detected one year later was 100%. CONCLUSIONS: This outbreak highlighted communication failures, from hunters to consumers. Awareness should be raised on the relation between trichinellosis and game meat. Trichinella species detection is important for adequate outbreak recording and could contribute to better understanding the clinical and serological signs of T. britovi infection.

A competitive enzyme-linked immunosorbent assay for rapid detection of antibodies against Trichinella spiralis and T. britovi - one test for humans and swine.

Infection with parasites from the Trichinella genus occurs in many vertebrates but disease only occurs in humans (trichinellosis). Humans are infected after the consumption of raw or undercooked meat from infected wild or domestic animals (usually swine or horses). Using the monoclonal antibody (mAb) 7C2C5, specific for an epitope unique to the muscle larvae of the genus Trichinella, we have developed a competitive enzyme-linked immunosorbent assay (c-ELISA) that enables the rapid detection of Trichinella-specific antibodies in sera originating from two different host species (human, swine) infected with either Trichinella spiralis or Trichinella britovi. This novel c-ELISA exhibited 100% specificity and sensitivity, as confirmed by a Western blot test. The assay is easy to use (one incubation step), and the time required for the procedure (45 min) is shorter than in any other ELISA format. This test could be useful for both the detection and surveillance of Trichinella infections.

Immunomodulatory potential of particular Trichinella spiralis muscle larvae excretory-secretory components.

Excretory-secretory antigens of Trichinella spiralis muscle larvae can induce the semi-matured status of rat dendritic cells. This may at least partly be the consequence of transient activation of extracellular signal-regulated kinases 1/2 (ERK1/2). Here we investigated the potential of several components of excretory-secretory antigens (native fraction containing 45, 49 and 53kDa proteins and recombinant Tsp53, representing one of the constituents of this fraction) to demonstrate previously observed effects of excretory-secretory antigens on dendritic cells in vitro, characterised by establishment of a particular phenotype (very low MHC II expression, moderate CD86 expression and significant ICAM-1 expression) and functional properties (low production of pro-inflammatory cytokine IL-12p70, and high production of IL-10 and TGF-ß). Dendritic cells activated by these components were able to provoke proliferation of naïve T cells and their polarisation towards Th2 and anti-inflammatory responses. The investigated antigens had almost the same capacity to induce IL-4 and IL-10 production from T cells as excretory-secretory antigens, but failed to induce significant TGF-ß synthesis. It could be concluded that the investigated excretory-secretory antigens components can largely reproduce the immunomodulatory effects of the complete excretory-secretory antigens and therefore may be considered as molecules important for creation of the anti-inflammatory milieu achieved by the parasite.