62 research outputs found
Immunomodulation by isometamidium (Samorin®) enhances prophylaxis against trypanosoma congolense infection
No full textThe objective of this project was to investigate effects of isometamidium (ISMM. Samorin®) on
immune responses to Trypanosoma congolense infection in order to understand mechanisms of
prophylaxis. (1) the efficacy of ISMM on T. congolense in vitro and in vivo was examined. (2) effects
on sheep peripheral blood mononuclear cell (PBMC) phenotypes, proliferation, and IFN-y production
were investigated. (3) effects on IL-12 and IFN-y production by mice splenic cells were studied. (4)
effects on sheep PBMC phenotypes following BCG vaccination in sheep were also investigated in
order to establish whether effects of ISMM were specific for trvpanosome antigens.Three groups consisting of four sheep were used in the trypanosome study. One group was
prophylactically treated with ISMM and one was used as a normal control group. Four and half
months later, all sheep were infected with T. congolense plus a third group that was later treated
with ISMM 14 days post infection. Two groups of three sheep were used in BCG experiments: one
was first treated with ISMM and 14 days after treatment both groups were inoculated with BCG
vaccine. The efficacy of ISMM on T. congolense was studied on cultures in vitro and in sheep and
mice in vivo. IL-12 and IFN-y production by mice splenic cells was investigated at different points
after ISMM treatmentPre-infection results showed a significant increase in IFN-y production by sheep PBMC 14 to 21 days
after ISMM administration when cultured with live tyrpanosomes. while cultures from the control
group were negative. No significant amounts of IFN-y were detected in all groups during the
infection period. ISMM prophylaxis suppressed polyclonal lymphocyte proliferation in vivo.
Increases in B-cells in the control and treated groups 14 to 21 days after infection were significantly
higher than in the prophy lactic group. A significant decrease in CD4" T-cells was recorded in the
control and treated groups 14 to 21 days post infection, while in the prophylactic group no changes
were observed. CD8~ T-cells increased only after treatment. The ratio of CD4LCD8" T-cells
significantly dropped 21 days after infection in the control and treated groups, while it increased in
the prophylactic group. There were no significant differences in CD5* and yS* T-cell responses.
Trypanosome specific IgG antibodies in serum of the prophy lactic group were significantly higher
than those in the control, while they were absent in the treated group. Following BCG vaccination,
ly mphocy te proliferation in vivo was suppressed in the ISMM treated group. The ratio of CD4LCD8
T-cells was higher in the ISMM group than in the control. Also ISMM. prevented a decrease in the
percentage of CD4~ T cells and suppressed polyclonal CD5" T cells and B cell expansion. Little or no
differences were observed on yd'. CD8" T cells, and PPD skin test. ISMM was trypanostatic in vitro
and T cell suppression decreased the prepatent period in prophylactically treated mice.In conclusion. ISMM prophylaxis modified cellular and antibody responses to T. congole
infection probably via the IFN-y and 1L-12 feedback mechanisms. This immunomodulation enhanced
prophylaxis and is not specific for trypanosome antigens since similar changes were observed
following BCG vaccination, although the end result of an infection may depend on the type of host
animal and nature of antigen
Impact of insecticide-treated nets and indoor residual spraying on malaria case prevalence in Geita and Nyang’hwale districts of Tanzania
No full textMalaria is a protozoan disease and one of the leading causes of illness and deaths in the world. Malaria is predominant in the tropics and subtropics, and it is reported that malaria kills a child every minute. In Tanzania at least 40% of outpatient attendances are attributable to malaria. This study assessed the impact of Insecticidetreated nets (ITNs) + indoor residual spraying (IRS) in Geita district, IRS alone in Nyang’hwale district and compared the two interventions between the two districts of Tanzania. In a retrospective cross-sectional study, district malaria surveillance data for five years (2011- 2015) and two years (2013-2014) were collected and analyzed for Geita and Nyang’hwale districts respectively. A total of 1,387,805 ITNs were distributed and 435,719 households sprayed between 2011 and 2015, however IRS coverage was uneven. There was evidence of malaria prevalence reduction from 53% to 12% in Geita district within the five years of intervention. The ITNs coverage was associated with a reduction in malaria prevalence while IRS was not. In Nyang’hwale district malaria cases increased from 103,788 to 123,337 cases in 2013 and 2014 respectively, and were accompanied by decreased households sprayed from 49,554 to 41,632. Furthermore, only ITNs had a significant effect in the combination. However, even at 100% ITNs coverage, the estimated probability of finding malaria cases would not be zero. Therefore, based on this study, the use of the two interventions that both use pyrethroids in combination has insignificant benefits and should be avoided unless IRS insecticide is not a pyrethroid
Metal and metalloid levels and bio-accumulation characteristics in soil, sediment, land plants and hippopotami (Hippopotamus amphibius L) from the South Luangwa National Park, Zambia
No full textHippopotami (Hippopotamus amphibius L) are large semi-aquatic mammals that can be exposed to metals and metalloid from both terrestrial and aquatic environments. Therefore, knowledge of metal and metalloid accumulation characteristics in hippopotami living in the national park is important from ecotoxicological point of view. Levels of toxic metals (Cd, Pb and Hg) and metalloid (As) in hippopotami liver from the South Luangwa National Park in Zambia were far lower compared to the established values of toxic levels in cattle. No temporal variations of metal levels in hippopotami were observed, probably because of good management condition and the lack of anthropogenic activities around the national park. However, hippopotami liver accumulated significantly higher concentrations of Hg compared to soil, sediment and their food (plants), most likely due to a process of biomagnifications throughout a trophic chain. Moreover, hippopotami liver and land plants showed significantly higher Cd levels than those of soil. These results strongly suggest that hippopotami liver accumulate higher levels of these metals if surrounding environment is contaminated. Levels of Cr and Ni in hippopotami liver were higher compared to other toxic metals. Since this is the first report to show the Cr and Ni levels and bio-accumulation characteristics of Hg and Cd in hippopotami, we concluded that continuous monitoring and evaluation of toxic effects of these metals on hippopotami should be conducted
Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia
No full textMetal (Cr, Co, Cu, Zn, Cd, Pb, Ni) and metalloid (As) accumulation was studied in roadside soil and wild rat (Rattus sp.) samples from near a Pb–Zn mine (Kabwe, Zambia) and the capital city of Zambia (Lusaka). The concentrations of the seven metals and As in the soil samples and Pb in the rat tissue samples were quantified using atomic absorption spectroscopy. The concentrations of Pb, Zn, Cu, Cd, and As in Kabwe soil were much higher than benchmark values. Geographic Information System analysis indicated the source of metal pollution was mining and smelting activity. Interestingly, the area south of the mine was more highly contaminated even though the prevailing wind flow was westward. Wild rats from Kabwe had much higher tissue concentrations of Pb than those from Lusaka. Their body weight and renal Pb levels were negatively correlated, which suggests that mining activity might affect terrestrial animals in Kabwe.
The area around Kabwe, Zambia is highly polluted with metals and As. Wild rats from this area had high tissue concentrations of Pb and decreased body weight
Heavy Metal Accumulation in Lake Sediments, Fish (Oreochromis niloticus and Serranochromis thumbergi), and Crayfish (Cherax quadricarinatus) in Lake Itezhi-tezhi and Lake Kariba, Zambia
No full textWe measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fish O. niloticus accumulated a very high concentration of Cu in Lake ITT, most likely due to the discharge of Cu waste from a mining area 450 km upstream. The aquatic species we sampled in Lake Kariba had higher concentrations of Cr, Ni, and Pb relative to those in Lake ITT. This is most likely due to anthropogenic activities, such as the use of leaded petrol and antifouling agents in marine paints. Interestingly, we observed a negative correlation between the coefficient of condition (K) and Ni concentration in the crayfish hepatopancreas. Both O. niloticus and the crayfish had much higher biota-sediment accumulation factors (BSAF) for Cu, Zn, and Cd relative to Cr, Co, Pb, and Ni. The rank of BSAF values for O. niloticus (Cu > Cd > Zn) and C. quadricarinatus (Zn > Cd > Cu) differed from the expected ranks based on the general order of affinity of metals (Cd >> Zn > Cu)
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