Geospatial Modelling and Univariate Analysis of Commensal Rodent-Borne Cestodoses: The Case of Invasive spp. of Rattus and Indigenous Mastomys coucha From South Africa

Poor socio-economic and unsanitary conditions are conducive to commensal rodent infestations, and these conditions are widespread in South Africa. Cestode species of zoonotic interest are highly prevalent in commensal rodents, such as invasive Rattus norvegicus, Rattus rattus, Rattus tanezumi, and indigenous Mastomys coucha, and have been frequently recovered from human stool samples. These cestode species have similar transmission dynamics to traditional soil-transmitted helminths (STHs), which ties them to infections associated with poverty and poor sanitation. Univariate analysis was used in the present study to determine the association between rodent-related factors and cestode prevalence, while ecological niche modelling was used to infer the potential distribution of the cestode species in South Africa. Cestode prevalence was found to be associated with older rodents, but it was not significantly associated with sex, and ectoparasite presence. The predicted occurrence for rodent-borne cestodes predominantly coincided with large human settlements, typically associated with significant anthropogenic changes. In addition, cestode parasite occurrence was predicted to include areas both inland and along the coast. This is possibly related to the commensal behaviour of the rodent hosts. The study highlights the rodent-related factors associated with the prevalence of parasites in the host community, as well as the environmental variables associated with parasite infective stages that influence host exposure. The application of geospatial modelling together with univariate analysis to predict and explain rodent-borne parasite prevalence may be useful to inform management strategies for targeted interventions.

Helminth composition and prevalence of indigenous and invasive synanthropic murid rodents in urban areas of Gauteng Province, South Africa

Although synanthropic rodents such as the indigenous species, Mastomys coucha, and the invasive species, Rattus norvegicus, R. rattus and R. tanezumi, are well-known to be hosts to various micro- and macroparasites, their helminth parasite fauna is poorly studied in South Africa. In an attempt to remedy the situation, the aim of the present study was to investigate the helminth fauna of these sympatric rodent species, which were obtained from the informal settlements of Alexandra, Tembisa, Diepsloot and residential suburbs of Pretoria and Hammanskraal, Gauteng Province, South Africa. Helminths were recovered from the urinary bladder, liver and gastrointestinal tract and were identified morphologically and molecularly. The recovered nematodes were all rodent-specific and included Aspiculuris tetraptera, Eucoleus sp., Heterakis spumosa, Mastophorus muris, Nippostrongylus brasiliensis, Protospirura sp., Strongyloides ratti, Syphacia obvelata, Syphacia muris, Trichuris sp. and Trichosomoides crassicauda. Syphacia obvelata, a commensal nematode of laboratory rodents, was recovered from indigenous M. coucha. Strobilar stages of cestodes recovered included Hymenolepis diminuta, Hymenolepis nana and Inermicapsifer madagascariensis. Recovered metacestodes were strobilocerci of Hydatigera taeniaeformis from all three invasive Rattus species and coenurostrobilocerci of Hydatigera parva from M. coucha. An acanthocephalan, Moniliformis moniliformis, was recovered from R. rattus only. All rodent species examined showed high helminth infection prevalence (≥70%) with equal or higher nematode than cestode prevalence. Mastomys coucha, however, showed significantly lower cestode prevalence than Rattus species where they co-occur. Interspecific transmission of helminths likely occurs between invasive and indigenous rodents, and these rodents harbour several helminths that have zoonotic implications.

Seroprevalence of Toxoplasma gondii infection in poultry kept under different housing conditions in Israel

A Toxoplasma gondii seroprevalence survey was conducted in poultry flocks kept under different housing systems in Israel. The seroprevalence rates were 35.4% (46/130) in battery-raised chicken egg-layers from Jerusalem which were first raised on the ground, 12.5% (19/152) in free-range chickens from various locations of the country and 9% (4/45) in turkeys from the north. However, all broilers (50) and chicken breeding stock (58) kept under high biosecurity conditions in Jerusalem were found to be T. gondii seronegative. It is concluded that high biosecurity conditions prevent contamination with oocysts by rendering premises inaccessible to cats.

First record of Acanthocheilonema dracunculoides from domestic dogs in Namibia

Acanthocheilonema dracunculoides was diagnosed in 2 dogs from Windhoek, Namibia, by acid phosphatase staining of microfilariae. This is the 1st record of A. dracunculoides in Namibia.

Cerebral cysticercosis in a cat

The metacestode of Taenia solium, Cysticercus cellulosae, was recovered from the brain of a cat showing central nervous clinical signs ante mortem. This is the first record of cerebral cysticercosis in a cat in South Africa.

Canine filariosis caused by Dirofilaria immitis in Mozambique: a small survey based on the identification of microfilariae

Dirofilaria immitis was diagnosed in 4 of 13 indigenous dogs from the Province of Zambézia, Mozambique, by acid phosphatase staining of microfilariae. The finding reconfirms the occurrence of the parasite in Mozambique after 3 decades and emphasises the need for extensive surveys. Additionally, in 1 of the infected dogs, microfilariae of Dipetalonema reconditum were detected, which is the 1st record of this parasite in Mozambique.

Dirofilaria repens in a cat with acute liver failure

Acute liver failure was diagnosed in a 12-year-old cat. Fine needle aspirate cytology revealed high numbers of unsheathed microfilariae and a hepatocellular reaction with no evidence of bacterial infection. The microfilariae were identified as those of Dirofilaria repens by acid phosphatase staining. The high number of microfilariae seen in both the blood and the liver aspirate samples as well as the favourable response to ivermectin amongst other drugs administered, is suggestive that D. repens was the cause of the liver insult. A positive result obtained with an antigen-capture ELISA (Dirochek) for Dirofilaria immitis antigen was interpreted as false. This is the 1st report of Dirofilaria repens for South Africa.

Cryopreservation of sheathed third-stage larvae of Gaigeria pachyscelis (Sandveld hookworm)

A technique for the cryopreservation of third stage larvae of Gaigeria pachyscelis is described. It consists of incubating sheathed third-stage larvae in 80% (v/v) ethylene glycol as a cryoprotectant for 30 s at 0 degrees C, prior to transfer into liquid nitrogen. The survival rate, as assessed by motility, was 37.6% after 30 d cryopreservation. A sheep infected percutaneously with 700 live cryopreserved third-stage larvae, harboured 41 adult worms (infectivity rate: 5.8%) when necropsied 78 d later.