King Shimumbo Nalubamba

Differential expression of pattern recognition receptors in the three pathological forms of sheep paratuberculosis.

Paratuberculosis is a chronic inflammatory disease of the gut caused by Mycobacterium avium subspecies paratuberculosis. Three forms have been described in sheep--paucibacillary, multibacillary and asymptomatic. The pauci- and multibacillary forms are characterized by type 1 and type 2 immune responses respectively; asymptomatic animals have no clinical signs or pathology. What determines this polarization is unknown, although pattern recognition receptors (PRR) have been implicated in other mycobacterial diseases. To investigate this in sheep paratuberculosis we used real-time RT-PCR to quantify the expression of fifteen PRR and adaptor genes from forty infected and nine control animals. These data show that there is a relationship between the different pathological forms and PRR transcript profiles. Nine PRRs were up-regulated in asymptomatic animals; with TLR9 being significantly raised in relation to the other three groups. Comparison of the three infected groups showed increases in many PRRs, with CARD15 and Dectin-2 being particularly high in both diseased groups. Significant differences between the pauci- and multibacillary animals included TLR2, CD14 and Dectin-1. Sequence analysis of TLR2 exon 2 and CARD15 exon 11 in the forty animals failed to identify any relationship between SNPs and pathological form.

Comparison of complement fixation test, competitive ELISA and LppQ ELISA with post-mortem findings in the diagnosis of contagious bovine pleuropneumonia (CBPP)

The complement fixation test (CFT), the c-ELISA and an indirect LppQ ELISA were compared to post-mortem (PM) inspection for the diagnosis of contagious bovine pleuropneumonia (CBPP). Sera from 797 cattle in the CBPP affected area of Kazungula, Zambia and 202 sera from Lusaka, Zambia, a CBPP-free area were used. The clinical history of CBPP was recorded and all the cattle from Kazungula were slaughtered and PM inspections conducted. The prevalence of CBPP in Kazungula was 67.5% (95%CI 67.2%, 70.8%), 52.6% (95%CI 49.2%, 56.2%), 59.0% (95%CI 55.5%, 62.4%) and 44.4% (95%CI 41.0%, 47.9%) using PM inspection, CFT, c-ELISA and LppQ ELISA, respectively. Three of the 202 negative control animals tested positive on the c-ELISA although they were from a known CBPP negative zone. In this study, the c-ELISA was more sensitive in detecting cattle with lesions in the chronic stage than any other test whilst the CFT detected more during the onset stage. No single serological test could detect all stages of CBPP infection, therefore the use of more than one test is advised.

Challenges of controlling contagious bovine pleuropneumonia in sub-Saharan Africa

Contagious bovine pleuropneumonia (CBPP) is a disease of economic importance that is widely distributed in sub-Saharan African and contributes significantly to cattle morbidity and mortality. Control of CBPP offers a number of challenges as a result many developing countries in Africa are still struggling with this disease. In this study, we look at the challenges encountered in CBPP control in sub-Saharan Africa from the Zambian perspective. In conducting this study, we reviewed scientific literature and reports from the Ministry of Agriculture and Livestock and related animal institutions, and also made interviews with experts and key government officials involved in CBPP control in Zambia. Among the challenges identified for the successful control of CBPP were as follows: failure in the delivery of veterinary services, lack of a cattle identification system, natural phenomenon, livestock husbandry systems in the traditional sector, human movements, traditional practices among cattle farmers and cattle marketing systems. It was seen that the epidemiology of CBPP in Zambia is influenced by both ecological and anthological factors. Therefore, design and implementation of any control or eradication programme should be area/regional-dependent taking into account the different factors influencing disease transmission and maintenance.

Prevalence of canine gastrointestinal helminths in urban Lusaka and rural Katete Districts of Zambia

Faecal samples were collected from January 2010 through September 2010 to determine the prevalence of gastrointestinal (GI) helminths infestation in dogs in urban Lusaka and rural Katete Districts of Zambia. A total of 452 faecal samples (n=160 Katete, n=292 Lusaka) were examined by faecal flotation for the presence of helminth eggs and 82.5% of dogs were positive for GI helminths in Katete compared to 76% for Lusaka. Positive results with the presence of at least one parasite corresponded to 72.9% Ancylostoma caninum, 11% Toxocara canis, 4.8% Toxascaris leonina, 2.4% Dipylidium caninum, 0.7% Taeniidae and 0.3% T. vulpis, species for Lusaka while Katete recorded 70.6% A. caninum, 18.1% T. vulpis, 11.1% T. canis, 13.1% D. caninum, 3.8% T. leonina, and 0.6% Taeniidae. Except for T. vulpis and D. caninum (p<0.05) the results indicated no significant difference in the prevalence of the identified GI helminth between Lusaka and Katete. There was no significant difference in the prevalence between genders of GI helminth infestation demonstrated in this study and only A. caninum showed significant difference in prevalence by age category. The study also showed the presence of zoonotic intestinal helminths A. caninum, T. canis and D. caninum. The study highlights that there was no significant difference in spectrum and prevalence of GI helminths between urban and rural areas in Zambia. It further brings to light the importance of educating owners of dogs on the importance of regular deworming of dogs and control of ectoparasites in order to minimise the risk that these dogs pose to them and the public.

A Review of Ecological Factors Associated with the Epidemiology of Wildlife Trypanosomiasis in the Luangwa and Zambezi Valley Ecosystems of Zambia

Trypanosomiasis has been endemic in wildlife in Zambia for more than a century. The disease has been associated with neurological disorders in humans. Current conservation strategies by the Zambian government of turning all game reserves into state-protected National Parks (NPs) and game management areas (GMAs) have led to the expansion of the wildlife and tsetse population in the Luangwa and Zambezi valley ecosystem. This ecological niche lies in the common tsetse fly belt that harbors the highest tsetse population density in Southern Africa. Ecological factors such as climate, vegetation and rainfall found in this niche allow for a favorable interplay between wild reservoir hosts and vector tsetse flies. These ecological factors that influence the survival of a wide range of wildlife species provide adequate habitat for tsetse flies thereby supporting the coexistence of disease reservoir hosts and vector tsetse flies leading to prolonged persistence of trypanosomiasis in the area. On the other hand, increase in anthropogenic activities poses a significant threat of reducing the tsetse and wildlife habitat in the area. Herein, we demonstrate that while conservation of wildlife and biodiversity is an important preservation strategy of natural resources, it could serve as a long-term reservoir of wildlife trypanosomiasis.

Differential expression of pattern recognition receptors during the development of foetal sheep.

Pattern recognition receptors (PRRs) play a crucial role in the initiation of the adaptive immune response. Immunological competence of foetal lambs occurs progressively throughout gestation, and in order to understand the role played by PRRs in foetal immunological competence, we quantified transcript expression, in the skin and spleen, of the TLRs, key C-type lectins and CARD15 during the critical second trimester. These data show that lambs express the same spectrum of PRRs as the adult but that the level of expression for most is dependent on developmental age. Key findings include: TLR1 and TLR5 are expressed at high levels in the foetus but are low in the adult; in contrast, TLR4, CD14 and CARD15 increase with age. In addition, TLR9 and TLR10 are expressed by the spleen and not the skin, while CARD15 is low in the spleen and high in the skin.

The epidemiology of canine Babesia infections in Zambia.

This study of 1196 dogs over a period of 18 months determined the seasonal infection patterns of canine babesiosis in Lusaka, the capital city of Zambia. The work also describes a retrospective study of the prevalence of canine babesiosis in laboratory clinical blood samples submitted to the University of Zambia, School of Veterinary Medicine for routine haematological examination from the year 1994 to 2009. A cross-sectional study was also performed to determine the levels of Babesia in a low-income society (during the dry season and the wet season of the year), where 361 samples were collected from dogs presented for mass rabies vaccination campaigns. Morphology of the Babesia indicated that all were of the large-sized Babesia canis infection. Babesia-positive dogs had significantly higher rectal temperatures than negative ones, and dogs younger than 1 year were more likely to be Babesia positive followed by those between 2 and 5 years old. Seasonal trends indicate two peaks, one in the rainy season (November-March) and another in the cold dry season (June/July). Monthly prevalence rates of Babesia ranged from 0% to 2.4% in natural populations and from 0% to 28.6% in laboratory specimens. This study shows that Zambia has lower Babesia prevalence than reported in other African countries.

A Cross-Sectional Study Investigating Cystic Hydatidosis in Slaughtered Cattle of Western Province in Zambia

A cross-sectional study was conducted from October 2007 to November 2008 to estimate the prevalence of hydatidosis in slaughtered cattle from two abattoirs in Mongu, Western Province, Zambia, using prospective and retrospective data. Out of the 4061 cattle examined during postmortem inspection, 84 (2.1%) were positive for hydatidosis. No cases were detected from Kaoma and Shangombo districts; however, prevalence ranged from 0.6% to 2.5% in districts where it was present. Sex was found to be positively associated with hydatidosis (P = 0.035) with female cattle being more likely to have hydatidosis (OR = 1.62). In the retrospective study (1994 to 2007), annual prevalence of hydatidosis ranged from 1.56% (n = 12,641) in 2006 to 4.7% (n = 2633) in 2001 with an overall prevalence of 3% (4689/158,456). This value is comparable to that observed in cattle slaughtered between October 2007 and November 2008 (2.1%). Hydatidosis was observed in the lungs (51.2%), liver (47.6%), and kidneys (1.2%). The percentage of viable cysts was 43.7%. This study confirms the presence of hydatidosis in cattle in Western Province of Zambia and estimates economic losses due to organ condemnations. Data presented herein provides a useful baseline for developing policy and intervention measures.

A seasonal survey of gastrointestinal parasites in captive wild impala antelope on a game facility south of Lusaka, Zambia.

Faecal samples (n = 1947) from captive wild impala (Aepyceros melampus melampus) were examined over a period of 14 months to determine quantitative seasonal helminth egg excretion patterns and qualitative protozoan oocyst excretion patterns. Geometric mean monthly faecal egg counts (FECs) ranged from 20 to 575 and coprocultures revealed three parasite genera, namely Trichostrongylus, Haemonchus and Strongyloides. Larvae of the Trichostrongylus spp. were most predominant from faecal cultures. No trematode eggs or lungworms were detected and eggs of the cestode Monezia were only seen in two samples during the entire study period. The nematode FECs showed a marked seasonal variation, being higher during the rainy season, moderate during the cool dry season and low during the hot dry season. The rainy season had significantly higher FECs than the dry season (P < 0.01). The percentage of helminth-egg positive faecal samples ranged from 90.6 to 100% in the rainy season and 72.4 to 85.6% in the dry season. Overall mean FECs in unpelleted faeces were significantly higher than in pelleted faeces (P < 0.01). However, the FECs were not significantly different among seasons in unpelleted faeces (P>0.05), but were significantly higher in pelleted faeces in the rainy season than the dry season (P < 0.05). Pellet size had a significant effect on FEC, with smaller pellets having higher FEC (P < 0.05). Strongyloides eggs and coccidia oocysts were only seen during the rainy season. This represents the first documentation of seasonal parasitic infestation in captive wild antelopes in Zambia. Treatment and control strategies for helminths in these captive wild impala are also suggested based on the findings from this study.

A Study of Naturally Acquired Canine Babesiosis Caused by Single and Mixed Babesia Species in Zambia: Clinicopathological Findings and Case Management

A retrospective and prospective analysis of clinical records of dogs diagnosed with Babesia infections was carried out for the years 2000 to 2013 from practices in Lusaka, Zambia. Records of 363 dogs with confirmed Babesia infections were analysed using demographic factors including sex, breed, age, and clinical signs in relation to haematological findings and Babesia species. The clinical and laboratory findings observed are described as well as Babesia species identification. The study included 18 breeds and the highest proportion were mongrels (32.2%), males representing 64.5% of the population. The most common presenting problems were anorexia (65.3%) and lethargy/weakness (65.3%). The most common clinical signs were fever (87.3%), pallor (52.3%), lymphadenopathy (47.4%), and presence of ticks (44.9%). Anaemia (96.4%) and nucleated erythrocytes (42.2%) were the most common laboratory findings. A mixed infection of Babesia rossi and Babesia gibsoni was present in 59.7% of dogs, whilst 8% and 32.2% had B. rossi and B. gibsoni as a single infection, respectively. Case management mainly involved therapy with tetracyclines and imidocarb and was usually accompanied by clinical improvement. This study highlights, for the first time, the presence of B. gibsoni in natural dog populations in Zambia, where previously only B. rossi was reported.