Lymphatic Filariasis Elimination Status: Wuchereria bancrofti Infections in Human Populations after Five Effective Rounds of Mass Drug Administration in Zambia.

Lymphatic filariasis (LF), also commonly known as elephantiasis, is a neglected tropical disease (NTD) caused by filarial parasites. The disease is transmitted via a bite from infected mosquitoes. The bites of these infected mosquitoes deposit filarial parasites, Wuchereria or Brugia, whose predilection site is the lymphatic system. The damage to the lymph system causes swelling in the legs, arms, and genitalia. A mapping survey conducted between 2003 and 2011 determined LF as being endemic in Zambia in 96 out of 116 districts. Elimination of LF is known to be possible by stopping the spread of the infection through large-scale preventive chemotherapy. Therefore, mass drug administration (MDA) with diethylcarbamazine citrate (DEC) (6 mg/kg) and Albendazole (400 mg) for Zambia has been conducted and implemented in all endemic districts with five effective rounds. In order to determine whether LF prevalence has been sufficiently reduced to levels less than 2% antigenemia and less than 1% microfilaremia, a pre-transmission assessment survey (pre-TAS) was conducted. Therefore, post-MDA pre-TAS was conducted between 2021 and 2022 in 80 districts to determine the LF prevalence. We conducted a cross-sectional seroprevalence study involving 600 participants in each evaluation unit (EU) or each district. The study sites (sentinel and spot-check sites) were from districts that were the implementation units (IUs) of the LF MDA. These included 80 districts from the 9 provinces. A total of 47,235 people from sentinel and spot-check locations were tested. Of these, valid tests were 47,052, of which 27,762 (59%) were females and 19,290 (41%) were males. The survey revealed in the 79/80 endemic districts a prevalence of Wb antigens of 0.14% and 0.0% prevalence of microfilariae. All the surveyed districts had an optimum prevalence of less than 2% for antigenaemia, except for Chibombo district. The majority of participants that tested positive for Wuchereria bancrofti (Wb) Antigens (Ag) were those that had 2, 3, and 4 rounds of MDA. Surprisingly, individuals that had 1 round of MDA were not found to have circulating antigens of Wb. The study showed that all the surveyed districts, except for Chibombo, passed pre-TAS. This further implies that there is a need to conduct transmission assessment surveys (TASs) in these districts.

Efficacy and safety of anthelmintics tested against Taenia solium cysticercosis in pigs.

Porcine cysticercosis, an infection caused by Taenia solium metacestodes, is continuously being reported in low-income countries of Latin America, Asia, and sub-Saharan Africa. The disease was declared eradicable by the International Task Force for Diseases Eradication (ITFDE) in 1993, and it is listed among the 17 WHO Neglected Tropical Diseases and Neglected Zoonoses that are potentially eradicable. In view of that, WHO has proposed a step-wise approach to its elimination, including chemotherapy of infected pigs. Different drugs have been tested on porcine cysticercosis with varying efficacies. These include flubendazole, fenbendazole, albendazole, albendazole sulphoxide, oxfendazole, praziquantel, and nitazoxanide. This review summarises available information on the efficacies and adverse effects shown by these drugs in pigs. Oxfendazole has shown to be effective for the control of porcine cysticercosis; however, it needs to be integrated with other control approaches. There is a need for standardised guidelines for evaluating the efficacy of anthelmintics against porcine cysticercosis, and more efficacy studies are needed since the conclusions so far are based on a limited number of studies using few infected pigs.

Efficacy of ivermectin and oxfendazole against Taenia solium cysticercosis and other parasitoses in naturally infected pigs.

Smallholder semi-confined pig production is a fast growing practice in sub-Saharan Africa with an unfortunate outcome of high prevalence of Taenia solium cysticercosis and other parasitoses. The widely used anthelmintic for control of endo and ecto-parasites in pigs in the area is ivermectin at a recommended dose of 0.3mg/kg. This study was conducted to evaluate the efficacy and safety in pigs after subcutaneous injection of ivermectin (IVM, 0.3mg/kg) and orally administration of oxfendazole (OFZ, 30mg/kg) in treatment of porcine cysticercosis and other parasitoses in naturally infected pigs. A total of 61 pigs with T. solium cysticercosis (38 males and 23 females) as identified by tongue palpation with age ranging from 3 to 24 months were recruited. The pigs were stratified based on sex, age and number of cysts on the tongue and randomly allocated to IVM, OFZ and control groups. Three days before treatment and two weeks after treatment faecal samples and skin scrapings were taken to establish the burden of endo- and ectoparasites, respectively and the effect of the treatment. No adverse effect was observed in any of the treatment groups throughout the study period. Half of the pigs from each group were slaughtered at week four and the remaining half at week twelve post treatment. The IVM treatment group had no significant effect (p=0.224) on T. solium cysts viability in comparison to the control group. Significant effect on cysts viability was observed in the OFZ treated group (p<0.001) compared to IVM and control groups in all muscle tissues. Regarding to brain cysts, neither of the drugs was efficacious. Ivermectin and OFZ treatments significantly reduced (p<0.001) the faecal egg count of Ascaris suum, strongyles and Trichuris suis two weeks after treatment. At slaughter, Oesophagostomum dentatum, Ascarops strongylina and Physocephalus sexalatus were recovered from pigs in the IVM treated and in the control groups. Ivermectin was 100% effective in control of Sarcoptes scabiei. In conclusion, IVM at a single dose of 0.3mg/kg was efficacious against ectoparasites but did not effectively cure pigs from T. solium cysticercosis or nematodes. Oxfendazole, on the other hand, killed all nematodes and muscle cysts, but did not have any effect on ectoparasites. A combination of the two drugs would be a most useful treatment option for control of pig parasitoses in sub-Saharan Africa.

Detection of cysteine protease in Taenia solium-induced brain granulomas in naturally infected pigs.

In order to further characterize the immune response around the viable or degenerating Taenia solium cysts in the pig brain, the involvement of cysteine protease in the immune evasion was assessed. Brain tissues from 30 adult pigs naturally infected with T. solium cysticercosis were subjected to histopathology using hematoxylin and eosin stain, and immunohistochemistry using caspase-3 antibodies. Histopathological evaluation revealed lesions of stage I which was characterized by presence of viable parasite surrounded with minimal to moderate inflammatory cells and stage III characterized by the presence of a disintegrating parasite surrounded with high inflammatory cells. The results of immunohistochemistry indicated caspase-3 positive cells interspaced between inflammatory infiltrate mainly in stage I lesions, indicating the presence of cysteine protease. This result confirms the earlier hypothesis that cysteine protease may play a role in inducing immune evasion through apoptosis around viable T. solium cysts.

The effect of oxfendazole treatment on muscle pathology in pigs infected with Taenia solium cysticercosis.

The aim of the present study was to test histopathologically the hypothesis that the time for clearing Taenia solium cysts in muscle tissue of pigs following treatment with oxfendazole is cyst density dependent. A total of 248 cyst lesions in the masseter muscle of 28 naturally infected pigs were examined 1, 4 and 8 weeks after oxfendazole (OFZ) treatment. As controls, half of the pigs received no treatment. Lesions were graded 0-V according to their inflammatory response, based on viability of the parasite, the degree and type of cellular response as well as deposition of collagen. Comparison of the degree of inflammatory response was made between treated and un-treated groups showing a significant difference in the mean grade of inflammatory response between 1 and 8 weeks after OFZ treatment. The OFZ treated pigs were further divided into 4 cyst intensity groups. The group with the highest cyst intensity had the lowest mean grade of inflammatory response and the group with the lowest cyst intensity had the highest mean grade of inflammatory response. Thus the present study supports the hypothesis that the time needed for the body to clear the cysts depends on the cyst intensity of individual pigs at the time of treatment.

Epilepsy and neurocysticercosis in sub-Saharan Africa.

Over the last decades, studies in sub-Saharan Africa have indicated that epilepsy is a highly prevalent neurological disorder. Causes may be varied with infections of the central nervous system playing an important role. Neurocysticercosis (NCC) has recently been recognised as an emerging public health problem and a growing concern throughout sub-Saharan Africa and has been estimated to be responsible for 30-50% of acquired epilepsy. NCC is closely linked with porcine cysticercosis and human taeniosis, the former reaching a prevalence of almost 50% in some pig populations. In this review, we first summarize prevalence data on epilepsy and highlight some special aspects of the disorder within sub-Saharan Africa. We then focus on the prevalence of NCC, clinical signs and symptoms and diagnostic criteria for NCC with special reference to sub-Saharan Africa. This is followed by a section on the latest developments regarding serodiagnosis of cysticercosis and a section on care management of people infected with NCC. NCC clearly represents a major risk factor of epilepsy, thus detecting and treating NCC may help cure epilepsy in millions of people in sub-Saharan Africa.