Control of Taenia solium taeniasis/cysticercosis: The best way forward for sub-Saharan Africa?

Taenia solium taeniasis/cysticercosis is a neglected parasitic zoonosis with significant economic and public health impacts. Control measures can be broadly grouped into community health education, improvements in hygiene and sanitary conditions, proper meat handling at household and community level, improved standards of meat inspection, pig management, treatment of individual patients and possibly human populations, and treatment and/or vaccination of porcine populations. This manuscript looks critically into currently existing control options and provides suggestions on which (combination of) tools would be most effective in the control of T. solium taeniasis/cysticercosis in sub-Saharan Africa. Field data and disease transmission simulations suggest that implementation of a single intervention control strategy will not lead to a satisfactory reduction of disease morbidity or transmission. A feasible strategy to combat T. solium taeniasis/cysticercosis would include a combination of approaches focussing on both human (health education and treatment) and animal host (management, treatment and vaccination), which can vary for different communities and different geographical locations. Selection of the specific strategy depends on cost-effectiveness analyses based on solid field data, currently unavailable, though urgently needed; as well as on health priorities and resources of the country. A One Health approach involving medical, veterinary, environmental and social sectors is essential for T. solium to be controlled and eventually eliminated. Finally the success of any intervention is largely dependent on the level of societal and political acceptance, commitment and engagement.

Detection of African swine fever virus DNA in blood samples stored on FTA cards from asymptomatic pigs in Mbeya region, Tanzania.

The aim of the study was to assess whether blood samples collected onto FTA(®) cards could be used in combination with real-time PCR for the detection of African swine fever virus (ASFV) DNA in samples from resource-poor settings under the assumption that asymptomatically (sub-clinically) infected pigs may be present. Blood samples were collected from clinically healthy pigs from Mbeya Region, Tanzania. The blood samples were stored on FTA(®) cards and analysed by real-time PCR assays in duplicate; three pigs had high levels of viral DNA (Ct values of 27-29), and three pigs had a low level of viral DNA (Ct 36-45). Four pigs were positive in one of the duplicate samples only, but clear products of the expected size were obtained when the reactions were analysed by gel electrophoresis. For comparison, blood samples from pigs experimentally infected with either a pathogenic (OURT T88/1) or a non-pathogenic (OURT T88/3) isolate of ASFV were collected, stored on FTA(®) cards and analysed in the same way. The blood from pigs infected with the OURT T88/1 isolate showed high levels of viral DNA (Ct 22-33), whereas infection with non-pathogenic OURT T88/3 isolate resulted in only low levels of viral DNA (Ct 39) in samples collected at 10-14 days after inoculation.

ASFV in Tanzania: asymptomatic pigs harbor virus of molecular similarity to Georgia 2007.

In 2011 African swine fever virus (ASFV) genome was detected in asymptomatic pigs in field samples in Mbeya, Tanzania. The aim of this paper is to partly characterize the virus that was harbored in these pigs and furthermore to confirm, by a second sampling, the latest occurrence of ASFV in the study area. ASFV genome was detected in serum from 10 out of 127 healthy European/crossbreed pigs. ASFV DNA was polymerase chain reaction (PCR) amplified and sequenced from sera with high viral loads using primers targeting p54 or p72. Both p54 and p72 had total identity to ASFV Genotype II (Georgia 2007/1). The ASFV epidemiology in Mbeya was studied in a new collection of 804 pig sera obtained in 2012. The antibody prevalence in four age groups (3-6 months.; 7-12 months; 13-18 months or 19-36 months) was 3-5%; all antibody positive sera were analyzed by PCR with negative results. The presence of antibodies in 3-month-old pigs confirms the circulation of ASFV in Mbeya several months after our detection of ASFV in asymptomatic pigs. The initial blood samples were obtained on Whatman FTA filter papers as dried blood samples. The samples were stored under field conditions and ASFV could be sequenced in DNA eluted 10 months later, showing the use of FTA samples. Studies on the genetic breed of the pigs are needed as well as sequence studies including the variable region of ASFV to elucidate why asymptomatic pigs with high viral loads were detected.

Smallholder pig production: prevalence and risk factors of ectoparasites.

A cross-sectional study was carried out in the Mbeya Region, Tanzania, with the aim of describing the distribution and diversity of ectoparasites on pigs, within confinement and free-range production systems of smallholder farms. A total of 128 farms were surveyed, with 96 practising confinement and 32 practising free-range production systems. The prevalence of ectoparasites on pigs within confinement and free-range production systems was 24% and 84%, respectively. Logistic regression analyses revealed that keeping pigs in a free-range system and the presence of neighbouring pigs were risk factors for ectoparasites. Within the confinement system, contact with neighbouring pigs and the time interval (in months) since last ectoparasitic treatment were additionally identified as risk factors. The prevalence of Haematopinus suis was 20% in confined pigs and 63% among free-range pigs. Free-ranging of pigs and presence of neighbouring pigs were also identified as risk factors for the presence of lice. Three species of fleas were identified; Tunga penetrans, Echidnophaga gallinacea and Ctenocephalides canis. The prevalence of fleas was 5% and 13% within confined and free-range, respectively. Two pigs (2%) were found infested with Sarcoptes scabiei var. suis. Ticks found belonged to four genera; Amblyomma spp., Rhipicephalus spp., Haemaphysalis spp., and Boophilus spp. The prevalence of hard ticks among the free-range pigs was 50%. Ectoparasites were more prevalent in the free-range system although highly prevalent within both production systems. Keeping pigs in a free-range system and contact with neighbouring pigs were main risk factors for the presence of ectoparasites. Confinement was highly effective as a preventive tool against hard ticks.