POTENTIAL CONTRIBUTION OF ADULT POPULATIONS TO THE MAINTENANCE OF SCHISTOSOMIASIS AND SOIL-TRANSMITTED HELMINTH INFECTIONS IN THE SIAVONGA AND MAZABUKA DISTRICTS OF ZAMBIA.

A majority of Zambian children live in impoverished communities that lack safe water and proper sanitation, exposing them to urogenital and intestinal helminths. Efforts to mitigate this plight have been implemented through mass drug administration aimed at deworming school-age and under-five children against schistosomiasis and soil-transmitted helminths. However, the disease status of adults living in the same communities as the treated children remains unknown. The aim of this study was to describe the potential contribution of infected adult populations to the transmission of these infections in southern Zambia. A cross-sectional study was conducted in April and May 2013 as part of baseline survey for a larger study in Mazabuka and Siavonga Districts. Stool and urine samples of 2829 adults from five catchment areas were collected and processed using Kato-Katz and urine filtration methods, respectively. Adults from Siavonga had a 13.9% combined prevalence of Schistosoma haematobium and S. mansoni, and 12.1% combined prevalence of Ascaris lumbricoides and hookworm. There was no S. mansoni in Mazabuka, and only a 5.3% prevalence of S. haematobium and 7.4% combined prevalence of A. lumbricoides and hookworm. Additionally, no Trichuris trichiura infections were observed in the two districts. Despite most of these infections being categorized as light intensity, heavy infection intensities were also found for all four parasite species. If this infected adult population is left untreated, the possibility of it acting as a reservoir of infections and ultimately transmitting the infections to treated children remains. Therefore, there is need to consider alternative treatment strategies that incorporate adults, thereby reducing the risk of contaminating the environment and perpetuating transmission to children.

Dogs' health and demographics in wildlife-populated and tsetse-infested villages of Mambwe district, eastern Zambia.

Good dog-keeping practices and access to veterinary care are essential for the well-being of dogs. As the main causes of morbidity and mortality in the rural canine population in Zambia are poorly understood, we followed a cohort of 162 indigenous dogs for six months in wildlife-populated and tsetse-infested villages of Mambwe district, eastern Zambia to gain deeper insights. Dogs lacked basic home and veterinary care, they were often starved and burdened with ticks, and some passed live adult worms in their stool. The frequent exposure of dogs to tsetse bites and consumption of fresh raw game meat and bones puts them at greater risk of acquiring African trypanosomiasis. Nearly 20 % of dogs were lost to follow-up, with the main causes being poor health (58.1 %), predation by wild carnivores (29 %), and owner culling or euthanasia (12.9 %). We observed that indigenous dogs' general well-being and survival were largely influenced by their environment, infectious diseases, injuries sustained during interaction with conspecifics and wildlife, and community attitudes and practices associated with dog ownership.

Molecular detection of Rickettsia felis in dogs, rodents and cat fleas in Zambia.

BACKGROUND: Flea-borne spotted fever is a zoonosis caused by Rickettsia felis, a Gram-negative obligate intracellular bacterium. The disease has a worldwide distribution including western and eastern sub-Saharan Africa where it is associated with febrile illness in humans. However, epidemiology and the public health risks it poses remain neglected especially in developing countries including Zambia. While Ctenocephalides felis (cat fleas) has been suggested to be the main vector, other arthropods including mosquitoes have been implicated in transmission and maintenance of the pathogen; however, their role in the epidemiological cycle remains to be elucidated. Thus, the aim of this study was to detect and characterize R. felis from animal hosts and blood-sucking arthropod vectors in Zambia. METHODS: Dog blood and rodent tissue samples as well as cat fleas and mosquitoes were collected from various areas in Zambia. DNA was extracted and screened by polymerase chain reaction (PCR) targeting genus Rickettsia and amplicons subjected to sequence analysis. Positive samples were further subjected to R. felis-specific real-time quantitative polymerase chain reactions. RESULTS: Rickettsia felis was detected in 4.7% (7/150) of dog blood samples and in 11.3% (12/106) of rodent tissue samples tested by PCR; this species was also detected in 3.7% (2/53) of cat fleas infesting dogs, co-infected with Rickettsia asembonensis. Furthermore, 37.7% (20/53) of cat flea samples tested positive for R. asembonensis, a member of spotted fever group rickettsiae of unknown pathogenicity. All the mosquitoes tested (n = 190 pools) were negative for Rickettsia spp. CONCLUSIONS: These observations suggest that R. felis is circulating among domestic dogs and cat fleas as well as rodents in Zambia, posing a potential public health risk to humans. This is because R. felis, a known human pathogen is present in hosts and vectors sharing habitat with humans.

Determination of the prevalence of African trypanosome species in indigenous dogs of Mambwe district, eastern Zambia, by loop-mediated isothermal amplification.

BACKGROUND: Dogs have been implicated to serve as links for parasite exchange between livestock and humans and remain an important source of emerging and re-emerging diseases including trypanosome infections. Yet, canine African trypanosomosis (CAT), particularly in indigenous dogs (mongrel breed) remains under- reported in literature. This study evaluated the performance of loop-mediated isothermal amplification (LAMP) in detecting trypanosomes in blood from indigenous dogs of tsetse-infested Mambwe district in eastern Zambia. METHODS: A cross sectional survey of CAT was conducted within 5 chiefdoms (Msoro, Kakumbi, Munkanya, Nsefu, Malama) of Mambwe district, eastern Zambia, during October 2012. Blood samples from 237 indigenous hunting dogs were collected and screened by microscopy and LAMP. RESULTS: Of the 237 dogs screened for CAT, 14 tested positive by microscopy (5.9%; 95% CI: 2.9 - 8.9%), all of which also tested positive by LAMP. In addition, LAMP detected 6 additional CAT cases, bringing the total cases detected by LAMP to 20 (8.4%; 95% CI: 4.9 - 12.0%). Irrespective of the detection method used, CAT was only recorded from 3 chiefdoms (Munkanya, Nsefu, Malama) out of the 5. According to LAMP, these infections were caused by Trypanosoma congolense, Trypanosoma brucei brucei and the zoonotic Trypanosoma brucei rhodesiense. Although these CAT cases generally did not manifest clinical illness, an association was observed between infection with Trypanosoma brucei subspecies and occurrence of corneal opacity. CONCLUSIONS: This communication reports for the first time the occurrence of CAT in indigenous Zambian dogs. Our study indicates that LAMP is a potential diagnostic tool for trypanosome detection in animals. LAMP was more sensitive than microscopy and was further capable of distinguishing the closely related T. b. brucei and T. b. rhodesiense. In view of the sporadic cases of re-emerging HAT being reported within the Luangwa valley, detection of the human serum resistant associated (SRA) gene in trypanosomes from mongrels is intriguing and indicative of the risk of contracting HAT by local communities and tourists in Mambwe district. Consequently, there is a need for continuous trypanosome surveillances in animals, humans and tsetse flies using sensitive and specific tests such as LAMP.