Rift Valley fever virus (RVFV) is an acute, zoonotic viral disease caused by a Phlebovirus, which belongs to the Bunyaviridae family. Among livestock, outbreaks of the disease are economically devastating. They are often characterised by large, sweeping abortion storms and have significant mortality in adult livestock. The aim of the current study was to investigate RVFV infection in the Kigoma region, which is nestled under the hills of the western arm of the Great Rift Valley on the edge of Lake Tanganyika, Tanzania. A region-wide serosurvey was conducted on non-vaccinated small ruminants (sheep and goats, n = 411). Sera samples were tested for the presence of anti-RVFV antibodies and viral antigen, using commercial enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction, respectively. The overall past infections were detected in 22 of the 411 animals, 5.4% (Confidence Interval (CI) 95% = 3.5% – 8.1%). The Kigoma rural area recorded the higher seroprevalence of 12.0% (CI 95% = 7.3% – 18.3%; p < 0.0001), followed by Kibondo at 2.3% (CI 95% = 0.5% – 6.5%; p > 0.05) and the Kasulu district at 0.8% (CI 95% = 0.0% – 4.2%; p > 0.05). The prevalence was 12.5% and 4.7% for sheep and goats, respectively. Reverse transcriptase polymerase chain reaction results indicated that only eight samples were found to be positive (n = 63). This study has confirmed, for the first time, the presence of the RVFV in the Kigoma region four years after the 2007 epizootic in Tanzania. The study further suggests that the virus activity exists during the inter-epizootic period, even in regions with no history of RVFV.

Since its discovery, polymerase chain reaction (PCR) has emerged as an important technology for the diagnosis and identification of infectious diseases. It is a highly sensitive and reliable nucleic acids (NA) detection tool for various sample types. However, stool, which carries the most abundant micro-organisms and physiological byproducts, remains to be the trickiest clinical specimen for molecular detection of pathogens. Herein, we demonstrate the novel application of hydrogel microparticles as carriers of viral RNA from stool samples without prior RNA purification for real-time polymerase chain reaction (qPCR). In each microparticle of primer-incorporated network (PIN) as a self-sufficient reaction compartment, immobilized reverse transcription (RT) primers capture the viral RNA by hybridization and directly initiate RT of RNA to generate a pool of complementary DNA (PIN-cDNA pool). Through a simple operation with a portable thermostat device, a PIN-cDNA pool for influenza A virus (IAV) was obtained in 20 min. The PIN-cDNA pools can be stored at room temperature, or directly used to deliver cDNA templates for qPCR. The viral cDNA templates were freely released in the subsequent qPCR to allow amplification efficiency of over 91%. The assay displayed good linearity, repeatability, and comparable limit of detection (LoD) with a commercialized viral RNA purification kit. As a proof of concept, this technology carries a huge potential for onsite application to improve human and animal infectious disease surveillance activities using stool samples without the need for a laboratory or centrifuge for sample preparation.

Emmanuel Kifaro details potential application of microparticles for active surveillance of viral infections from non-invasive animal matrices

Bat ectoparasites are important components of bat communities and have close ecological relationships with their hosts. Eucampsipoda africana (E. africana) is a wingless bat fly that parasitizes Egyptian fruit bats (Rousettus aegyptiacus), but its occurrence and host association have received little attention in Tanzania. A descriptive cross-sectional study was conducted in which 269 bat flies were collected from Egyptian fruit bats and analyzed using morphological identification, mitochondrial cytochrome c oxidase subunit I (COI) gene sequencing, and blood-meal analysis. Out of the 193 bats examined, 37.3% (72/193; 95% CI: 30.5-44.5%) of the bats were infested with at least one bat fly. Binary logistic regression showed that age, sex, and village were significantly associated with fly infestation. Adults had higher odds of infestation than juveniles (OR = 4.59, 95% CI: 1.87-11.28), while males had lower odds than females (OR = 0.49, 95% CI: 0.25-0.96). Infestation also differed significantly among villages. COI sequences showed 100% nucleotide identity with reference E. africana sequences available in GenBank, and phylogenetic analysis clustered the Tanzanian samples with previously reported E. africana in Zambia. Blood-meal analysis corroborated the field assumption that these flies have an association with Rousettus aegyptiacus (R. aegyptiacus). These findings represent the first molecular confirmation of E. africana associated with R. aegyptiacus and of its prevalence in Kagera Region-Tanzania.