Identifying wildlife reservoirs of neglected taeniid tapeworms: Non-invasive diagnosis of endemic Taenia serialis infection in a wild primate population.

Despite the global distribution and public health consequences of Taenia tapeworms, the life cycles of taeniids infecting wildlife hosts remain largely undescribed. The larval stage of Taenia serialis commonly parasitizes rodents and lagomorphs, but has been reported in a wide range of hosts that includes geladas (Theropithecus gelada), primates endemic to Ethiopia. Geladas exhibit protuberant larval cysts indicative of advanced T. serialis infection that are associated with high mortality. However, non-protuberant larvae can develop in deep tissue or the abdominal cavity, leading to underestimates of prevalence based solely on observable cysts. We adapted a non-invasive monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) to detect circulating Taenia spp. antigen in dried gelada urine. Analysis revealed that this assay was highly accurate in detecting Taenia antigen, with 98.4% specificity, 98.5% sensitivity, and an area under the curve of 0.99. We used this assay to investigate the prevalence of T. serialis infection in a wild gelada population, finding that infection is substantially more widespread than the occurrence of visible T. serialis cysts (16.4% tested positive at least once, while only 6% of the same population exhibited cysts). We examined whether age or sex predicted T. serialis infection as indicated by external cysts and antigen presence. Contrary to the female-bias observed in many Taenia-host systems, we found no significant sex bias in either cyst presence or antigen presence. Age, on the other hand, predicted cyst presence (older individuals were more likely to show cysts) but not antigen presence. We interpret this finding to indicate that T. serialis may infect individuals early in life but only result in visible disease later in life. This is the first application of an antigen ELISA to the study of larval Taenia infection in wildlife, opening the doors to the identification and description of infection dynamics in reservoir populations.

Taeniasis among Refugees Living on Thailand-Myanmar Border, 2012.

We tested refugee camp residents on the Thailand-Myanmar border for Taenia solium infection. Taeniasis prevalence was consistent with that for other disease-endemic regions, but seropositivity indicating T. solium taeniasis was rare. Seropositivity indicating cysticercosis was 5.5% in humans, and 3.2% in pigs. Corralling pigs and providing latrines may control transmission of these tapeworms within this camp.

Exposure to multiple parasites is associated with the prevalence of active convulsive epilepsy in sub-Saharan Africa.

BACKGROUND: Epilepsy is common in developing countries, and it is often associated with parasitic infections. We investigated the relationship between exposure to parasitic infections, particularly multiple infections and active convulsive epilepsy (ACE), in five sites across sub-Saharan Africa. METHODS AND FINDINGS: A case-control design that matched on age and location was used. Blood samples were collected from 986 prevalent cases and 1,313 age-matched community controls and tested for presence of antibodies to Onchocerca volvulus, Toxocara canis, Toxoplasma gondii, Plasmodium falciparum, Taenia solium and HIV. Exposure (seropositivity) to Onchocerca volvulus (OR = 1.98; 95%CI: 1.52-2.58, p<0.001), Toxocara canis (OR = 1.52; 95%CI: 1.23-1.87, p<0.001), Toxoplasma gondii (OR = 1.28; 95%CI: 1.04-1.56, p = 0.018) and higher antibody levels (top tertile) to Toxocara canis (OR = 1.70; 95%CI: 1.30-2.24, p<0.001) were associated with an increased prevalence of ACE. Exposure to multiple infections was common (73.8% of cases and 65.5% of controls had been exposed to two or more infections), and for T. gondii and O. volvulus co-infection, their combined effect on the prevalence of ACE, as determined by the relative excess risk due to interaction (RERI), was more than additive (T. gondii and O. volvulus, RERI = 1.19). The prevalence of T. solium antibodies was low (2.8% of cases and 2.2% of controls) and was not associated with ACE in the study areas. CONCLUSION: This study investigates how the degree of exposure to parasites and multiple parasitic infections are associated with ACE and may explain conflicting results obtained when only seropositivity is considered. The findings from this study should be further validated.

Seroprevalence of antibodies against Taenia solium cysticerci among refugees resettled in United States.

Neurocysticercosis (NCC) is a disease caused by central nervous system infection by the larval stage of the pork tapeworm, Taenia solium. In developing countries, NCC is a leading cause of adult-onset epilepsy. Case reports of NCC are increasing among refugees resettled to the United States and other nations, but the underlying prevalence among refugee groups is unknown. We tested stored serum samples from the Centers for Disease Control and Prevention Migrant Serum Bank for antibodies against T. solium cysts by using the enzyme-linked immunoelectrotransfer blot. Seroprevalence was high among all 4 populations tested: refugees from Burma (23.2%), Lao People's Democratic Republic (18.3%), Bhutan (22.8%), and Burundi (25.8%). Clinicians caring for refugee populations should suspect NCC in patients with seizure, chronic headache, or unexplained neurologic manifestations. Improved understanding of the prevalence of epilepsy and other associated diseases among refugees could guide recommendations for their evaluation and treatment before, during, and after resettlement.

Schistosomiasis in expatriates in the Arusha region of Tanzania.

BACKGROUND: In 1996 the seroprevalence of schistosomiasis in expatriates and travelers who had contact with Lake Malawi, a fresh water source thought to be schistosomiasis-free, was measured at 32%. Clinicians in Arusha, Tanzania, questioned the prevalence of Schistosoma infection in expatriates living in the Arusha region, and how schistosomiasis might relate to symptoms of chronic fatigue in Arusha expatriates. METHOD: We performed a cross-sectional survey of 80 expatriates living in the Arusha region of Tanzania to determine the seroprevalence of schistosome infection. Whole blood was analyzed by the Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) for the presence of species-specific Schistosoma mansoni and Schistosoma haematobium antibodies to microsomal antigens of adult Schistosoma worms, followed by confirmatory enzyme-linked immunoelectrotransfer blot (Western blot). Volunteers answered a questionnaire which included length of residence in Arusha, risk factors, symptoms, and previous diagnosis of schistosomiasis. RESULTS: Of the 80 expatriates sampled, 8 (10%) were positive for schistosomiasis (6 to S. mansoni only, 1 to S. haematobium, 1 to both species). Significant risk factors, elicited by questionnaire, included longer residence in the Arusha region (p =.020), history of fatigue (p =.010) and myalgias (p =.047), and previous diagnosis of schistosomiasis by stool or urine ova (p =.0007). CONCLUSION: The lower seroprevalence of schistosomiasis in Arusha expatriates, compared with expatriates and travelers to Lake Malawi, suggests a regional variation of rate of schistosomiasis infection. Although a history of fatigue and myalgias was related to seropositivity, there is no strong evidence that schistosomiasis infection is the cause of chronic fatigue in Arusha expatriates.