Browsing by Author "Mulambalah, CS."

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Changes in lipids utilisation during moisture and temperature stress of infective (L3) and its implication on the epidemiology of Haemonchus contortus in arid and semi arid lands
(Maxwell science publishing, 2011-03-05) Siamba, Donald N.; Gatongi, PM.; Mulambalah, CS.; Ngeiywa, MM.; Wamae, LW.; Wambugu, A.
A study was undertaken to establish the pattern and level of lipid utilization in third stage infective larvae (L_3) of Haemonchus contortus under temperature and moisture stress conditions. The stress factors were representative of an arid and semi arid site in Kenya. The L_3 were subjected to gradual increase and reduction in temperature and moisture, respectively, using a programmable cold/heat testing chamber. Optical density per area (Corrected average pixels) derived from image analysis of individual stained larvae using an image analysis software (UN SCAN IT gel^(r)), were used to estimate the lipid content of larvae subjected to different stress treatments. It was observed that lipid content of the L_3 declined and was negatively correlated with duration of exposure with significantly (p = 0.012) lower rates in moisture compared to temperature stressed L3. It was also observed that the decline occurred in phases signifying possible adaptive physiological process aimed at preserving lipid reserves and viability. During revival, there was a drastic decline in lipid reserves probably as a result of increased lipid utilisation by the reviving larvae. The epidemiological significance of these findings in field larvae is discussed
Evaluation of lambda-cyhalothrin persistence on different indoor surfaces in a malaria epidemic-prone area in Kenya.
(Medwell online, 2010) Mulambalah, CS.; Siamba, Donald N.; Ngeiywa, MM.; Vulule, JM.
The residual life of pyrethroid insecticide lambdacyhalothrin (trade name: ICON) on indoor surfaces was evaluated under field conditions in villages in a highland area of Kipsamoite, North Nandi District of Kenya. About 10% lambda-cyhalthrin wettable powder was sprayed at the rate of 0.02-0.03 g m-2 on the indoor wall surface of randomly selected local houses. Its effect on mortality of Anopheles gambiae s.s as test vector was assessed from January to April 2007. Wall bioassays were conducted on different treated wall surfaces using plastic cones attached to treated surfaces at fortnightly intervals. Mortality rate in mosquitoes exposed to treated surfaces varied according to the type of wall that received the insecticide. ICON was more stable and lasted longer on mud and wood surfaces. There was significant difference between persistence of ICON on mud and other surfaces tested. For the insecticide formulation used, the duration of the residual effect was satisfactory up to the WHOPES recommended post spray period. Beyond this period, persistence declined rapidly on metal and cemented/brick plastered surfaces. The low effectiveness of the formulation on metal and cement surfaces should be considered together with the importance of residual spraying as a vector control method in the area. We concluded that the use of ICON in IRS could be a single and effective strategy to control endophiliic and antropophilic malaria vectors in malaria hypoendemic area. This is based on the findings that the local vector is susceptible to ICON and most of the houses had mud surfaces and malaria transmission is seasonal. In this regard, one round of ICON spray would be sufficient to interrupt 3-4 month seasonal malaria transmission in the study area. Apart from its toxicity to mosquitoes, ICON also agitates and repels mosquitoes that do not come in contact with it and therefore an added benefit of reducing the indoor malaria vector densities. This would drastically reduce human-vector contact and overall decline in community malaria prevalence.
Exsheathment characteristics and infectivity of revived anhydrobiotic L_ (3) of haemonchus contortus
(Maxwell science, 2012-10-20) Siamba, Donald N.; Mulambalah, CS.; Ngemaeiywa, MM.; Gatongi, PM.; Wamae, LW.
This study was conducted to determine the effect of temperature and moisture stress on exsheathment process and infectivity of the infective larvae of the parasitic nematode ＂Haemonchus contortus＂. Laboratory conditions were used in which infective (L_(3)) of ＂H. contortus＂ were either subjected to gradually increasing temperatures, decreasing moisture or both. Post stress viability and exsheatment of L_(3) was determined prior to infection experiments. The viability of ＂H. contortus＂ after induction of anhydrobiosis declined significantly (p＜0.05) from 85 to 60% in about 60 days. The results showed significant (p＜0.05) delay in exsheathment in stressed larvae compared to unstressed larvae leading to low overall establishment (Infection). However, the proportion of the immature in relation to the mature parasites (hypobiosis) was significantly (p＜0.05) higher in stressed compared to the unstressed L_(3). These results indicate that delayed exsheatment in stressed L_(3) contributes to low infectivity in ruminants.
Stress response in infective larvae (L3) of the parasitic nematode haemonchus Contortus is accompanied by enhanced expression of heat shock proteins (HSP 70)
(Maxwell science, 2012-07-10) Siamba, Donald N.; Gatongi, PN.; Mulambalah, CS.; Ngeiywa, MM.; Wamae, LW.
The study was undertaken to investigate the effects of temperature and moisture stresses on protein profile and characteristics in the free living third larval stages (L_3) of Haemonchus contortus. Before and after temperature and moisture stress treatment, the L_3 were tested for the induction and expression of Heat-Shock Proteins (HSPs). Proteins were analyzed by Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and immunoblot analysis with alkaline-phosphatase conjugated anti HSP 70 antibody. The stress resulted in an altered protein pattern. It was also revealed that stress treatment did not alter the signals obtained with the anti HSP 70 antibody, but the amount of HSP70 as estimated by densitometry differed between pre and post stress samples. This response in the free living third stage larvae (L_3) of H. contortus may be aimed at protecting the parasite against molecular damage and ensuring survival during stressful periods.