Immunochromatographic thread-based test platform for diagnosis of infectious diseases

This research article published by Springer Nature Switzerland AG., 2018Patterning is an important step in fabrication of multiplexed microfluidic devices. Various approaches including cutting, photolithography, wax-printing, plotting and etching have been developed and tested. Recently, using threads has emerged as a convenient and low-cost approach for fabrication of microfluidic devices. We explored the application of threads in combination with nitrocellulose membrane to fabricate multi-channel immunochromatographic diagnostic devices. Microfluidic channels were made using hydrophilic threads and nitrocellulose membrane strips. Household sewing needle was used to weave hydrophilic thread into desired patterns through a double-sided mounting tape. Glass fibre discs were used as conjugate pads while nitrocellulose membrane was used for immobilisation of capture antibodies. Patterned threads were linked to nitrocellulose membrane strips by overlapping so that reagents flowing through threads were eventually transferred to the membrane. The design was tested using IgG, H. pylori and Hepatitis B surface antigen. Continuous flow was observed from hydrophilic threads to the nitrocellulose membrane, and a positive signal was visualised on the membrane within 5 min of sample application. The observed limit of detection ranged between 30 and 300 ng/ml for H. pylori and Hepatitis B, respectively. Using thread and tape offers a promising alternative for patterning of simple, low-cost multiplexed microfluidic diagnostic devices with potential point-of-care applications in resource-limited settings

Seroprevalence of foot and mouth disease in the wildlife-livestock interface and non-interface areas in Tanzania

Abstract A cross sectional study was conducted in the Serengeti ecosystem (wildlife-livestock interface) and central part of Tanzania (non-interface) area to determine the prevalence of foot and mouth disease (FMD) in Serengeti, Bunda, Kongwa and Iramba Districts. Seroprevalence investigation using 3ABC-ELISA technique indicated that the overall prevalence of antibodies against FMD virus was 66.3%. Significantly high prevalence was recorded in wildlifelivestock interface areas (71.5%) compared to non-interface areas (61.0%). District-wise, higher prevalence was recorded in Kongwa district (89.0%) followed by Serengeti (78.0%), Bunda (65.0%) and Iramba (33.0%). Specieswise, higher prevalence was found in bovines (69.8%), ovines (52.4%) and caprines (11.1%). From various risk factors, ecosystem distribution (X 2 = 4.9308, p = 0.0264) and species distribution (X 2 = 28.3236, P = 0.0001), the results indicated that FMD is highly prevalent in wildlife-livestock interface areas than in non-interface areas. However, uncontrolled livestock movement in Kongwa District resulted into much higher FMD prevalence than in districts where there is wildlife-livestock interface. The presence of antibodies against FMD virus in species other than cattle revealed that there is a need to consider other species in planning for FMD control

Foot-and-mouth disease seroprevalence and socioeconomic impact in relation to animal movements in selected wildlife-livestock interface and non interface areas of Tanzania

Master of PHILOSOPHYFoot-and-mouth disease (FMD) is an acute, highly contagious viral infection of domestic and wild cloven-hoofed animals. In Tanzania the disease is known to be endemic with periodic outbreaks occurring in different geographical areas. This study was conducted to determine the seroprevalence and socio-economic impact of FMD in relation to livestock movements in a wildlife–livestock interface ecosystem (Serengeti and Bunda Districts) compared to a noninterface ecosystem (Iramba and Kongwa Districts). The study attempted to establish the socio-economic impact of FMD in these study districts. Four hundred serum samples were collected from Serengeti (n = 100), Bunda (n = 100), Kongwa (n = 100) and Iramba (n = 100) and tested for FMD antibodies presence using 3ABC-ELISA. In addition, forty questionnaire copies to establish the socio-economic impact of FMD were administered to livestock keepers: Serengeti (n = 10), Bunda (n = 10), Kongwa (n =10) and Iramba (n = 10). Significantly higher association between geographical areas and seroprevalence was recorded in the wildlife-livestock interface areas (71.5%; 143/200) compared to non-interface areas (61.0%; 122/200) (X2 = 4.9308, p = 0.0264, C.F 95%). Socially, FMD outbreaks impact on food insecurity (85.0%), failure to meet education costs (90.0%) and medical costs (77.5%). Economically, FMD impacts were observed in losses associated with treatment costs (87.5%), milk productivity (85.0%), draught power (80.0%), livestock market loss (67.5), lower livestock weight gain (60.0%), lower fertility (37.5%), abortion (35.0%), death of animals (25.0%) and vaccine supply costs (2.5%). In conclusion, FMD is more prevalent at the wildlife-livestock interface (71.5%) than in non-interface areas (61.0%). Higher percentages in case response on social impacts and economic losses indicate magnitude of the problem and feelings of livestock keepers about FMD in both ecosystems. However, lower percentage on case response to vaccine supply cost indicates there is no control of FMD by vaccination.Wellcome Trust Southern African Centre for Infectious Disease Surveillance (SACIDS

Challenges in Diagnosis of Febrile illnesses in Tanzania in the Era of Declining Malaria Epidemiology

Research Article published by American Journal of Research Communication Vol 3(5)Malaria and other febrile illnesses are very common especially in children in developing countries. Due to reliance on clinical algorithms for diagnosis in resource-poor settings, most febrile episodes have always been attributed to malaria. However, continuous malaria monitoring and recent improvements in malaria diagnosis have revealed a progressive decline in malaria and significant involvement of non-malarial etiologies in most febrile cases. This paper highlights the situation of malarial and non-malarial fevers, challenges facing the health sector, and possible approaches to addressing these challenges for better diagnosis of non-malarial febrile illnesses in Tanzania

Review of Peste des Petits Ruminants Occurrence and Spread in Tanzania

Peste des petits ruminants (PPR) is an important transboundary animal disease of domestic small ruminants, camels, and wild artiodactyls. The disease has significant socio-economic impact on communities that depend on livestock for their livelihood and is a threat to endangered susceptible wild species. The aim of this review was to describe the introduction of PPR to Tanzania and its subsequent spread to different parts of the country. On-line databases were searched for peer-reviewed and grey literature, formal and informal reports were obtained from Tanzanian Zonal Veterinary Investigation Centres and Laboratories, and Veterinary Officers involved with PPR surveillance were contacted. PPR virus (PPRV) was confirmed in northern Tanzania in 2008, although serological data from samples collected in the region in 1998 and 2004, and evidence that the virus was already circulating in Uganda in 2003, suggests that PPRV might have been present earlier than this. It is likely that the virus which became established in Tanzania was introduced from Kenya between 2006–7 through the cross-border movement of small ruminants for trade or grazing resources, and then spread to eastern, central, and southern Tanzania from 2008 to 2010 through movement of small ruminants by pastoralists and traders. There was no evidence of PPRV sero-conversion in wildlife based on sera collected up to 2012, suggesting that they did not play a vectoring or bridging role in the establishment of PPRV in Tanzania. PPRV lineages II, III and IV have been detected, indicating that there have been several virus introductions. PPRV is now considered to be endemic in sheep and goats in Tanzania, but there has been no evidence of PPR clinical disease in wildlife species in Tanzania, although serum samples collected in 2014 from several wild ruminant species were PPRV sero-positive. Similarly, no PPR disease has been observed in cattle and camels. In these atypical hosts, serological evidence indicates exposure to PPRV infection, most likely through spillover from infected sheep and goats. Some of the challenges for PPRV eradication in Tanzania include movements of small ruminants, including transboundary movements, and the capacity of veterinary services for disease surveillance and vaccination. Using wildlife and atypical domestic hosts for PPR surveillance is a useful indicator of endemism and the ongoing circulation of PPRV in livestock, especially during the implementation of vaccination to control or eliminate the disease in sheep and goats. PPR disease has a major socio-economic impact in Tanzania, which justifies the investment in a comprehensive PPRV eradication programme

The evaluation of five serological assays in determining seroconversion to peste des petits ruminants virus in typical and atypical hosts

Abstract Peste des petits ruminants (PPR) is an infectious viral disease, primarily of small ruminants such as sheep and goats, but is also known to infect a wide range of wild and domestic Artiodactyls including African buffalo, gazelle, saiga and camels. The livestock-wildlife interface, where free-ranging animals can interact with captive flocks, is the subject of scrutiny as its role in the maintenance and spread of PPR virus (PPRV) is poorly understood. As seroconversion to PPRV indicates previous infection and/or vaccination, the availability of validated serological tools for use in both typical (sheep and goat) and atypical species is essential to support future disease surveillance and control strategies. The virus neutralisation test (VNT) and enzyme-linked immunosorbent assay (ELISA) have been validated using sera from typical host species. Still, the performance of these assays in detecting antibodies from atypical species remains unclear. We examined a large panel of sera (n = 793) from a range of species from multiple countries (sourced 2015–2022) using three tests: VNT, ID VET N-ELISA and AU-PANVAC H-ELISA. A sub-panel (n = 30) was also distributed to two laboratories and tested using the luciferase immunoprecipitation system (LIPS) and a pseudotyped virus neutralisation assay (PVNA). We demonstrate a 75.0–88.0% agreement of positive results for detecting PPRV antibodies in sera from typical species between the VNT and commercial ELISAs, however this decreased to 44.4–62.3% in sera from atypical species, with an inter-species variation. The LIPS and PVNA strongly correlate with the VNT and ELISAs for typical species but vary when testing sera from atypical species

Peste des Petits Ruminants Virus Infection at the Wildlife–Livestock Interface in the Greater Serengeti Ecosystem, 2015–2019

International audiencePeste des petits ruminants (PPR) is a viral disease of goats and sheep that occurs in Africa, the Middle East and Asia with a severe impact on livelihoods and livestock trade. Many wild artiodactyls are susceptible to PPR virus (PPRV) infection, and some outbreaks have threatened endangered wild populations. The role of wild species in PPRV epidemiology is unclear, which is a knowledge gap for the Global Strategy for the Control and Eradication of PPR. These studies aimed to investigate PPRV infection in wild artiodactyls in the Greater Serengeti and Amboseli ecosystems of Kenya and Tanzania. Out of 132 animals purposively sampled in 2015–2016, 19.7% were PPRV seropositive by ID Screen PPR competition enzyme-linked immunosorbent assay (cELISA; IDvet, France) from the following species: African buffalo, wildebeest, topi, kongoni, Grant’s gazelle, impala, Thomson’s gazelle, warthog and gerenuk, while waterbuck and lesser kudu were seronegative. In 2018–2019, a cross-sectional survey of randomly selected African buffalo and Grant’s gazelle herds was conducted. The weighted estimate of PPRV seroprevalence was 12.0% out of 191 African buffalo and 1.1% out of 139 Grant’s gazelles. All ocular and nasal swabs and faeces were negative by PPRV real-time reverse transcription-polymerase chain reaction (RT-qPCR). Investigations of a PPR-like disease in sheep and goats confirmed PPRV circulation in the area by rapid detection test and/or RT-qPCR. These results demonstrated serological evidence of PPRV infection in wild artiodactyl species at the wildlife–livestock interface in this ecosystem where PPRV is endemic in domestic small ruminants. Exposure to PPRV could be via spillover from infected small ruminants or from transmission between wild animals, while the relatively low seroprevalence suggests that sustained transmission is unlikely. Further studies of other major wild artiodactyls in this ecosystem are required, such as impala, Thomson’s gazelle and wildebeest