Evaluation of alternative mosquito sampling methods for malaria vectors in Lowland South - East Zambia.

Sampling malaria vectors and measuring their biting density is of paramount importance for entomological surveys of malaria transmission. Human landing catch (HLC) has been traditionally regarded as a gold standard method for surveying human exposure to mosquito bites. However, due to the risk of human participant exposure to mosquito-borne parasites and viruses, a variety of alternative, exposure-free trapping methods were compared in lowland, south-east Zambia. Centres for Disease Control and Prevention miniature light trap (CDC-LT), Ifakara Tent Trap model C (ITT-C), resting boxes (RB) and window exit traps (WET) were all compared with HLC using a 3 × 3 Latin Squares design replicated in 4 blocks of 3 houses with long lasting insecticidal nets, half of which were also sprayed with a residual deltamethrin formulation, which was repeated for 10 rounds of 3 nights of rotation each during both the dry and wet seasons. The mean catches of HLC indoor, HLC outdoor, CDC-LT, ITT-C, WET, RB indoor and RB outdoor, were 1.687, 1.004, 3.267, 0.088, 0.004, 0.000 and 0.008 for Anopheles quadriannulatus Theobald respectively, and 7.287, 6.784, 10.958, 5.875, 0.296, 0.158 and 0.458, for An. funestus Giles, respectively. Indoor CDC-LT was more efficient in sampling An. quadriannulatus and An. funestus than HLC indoor (Relative rate [95% Confidence Interval] = 1.873 [1.653, 2.122] and 1.532 [1.441, 1.628], respectively, P < 0.001 for both). ITT-C was the only other alternative which had comparable sensitivity (RR = 0.821 [0.765, 0.881], P < 0.001), relative to HLC indoor other than CDC-LT for sampling An. funestus. While the two most sensitive exposure-free techniques primarily capture host-seeking mosquitoes, both have substantial disadvantages for routine community-based surveillance applications: the CDC-LT requires regular recharging of batteries while the bulkiness of ITT-C makes it difficult to move between sampling locations. RB placed indoors or outdoors and WET had consistently poor sensitivity so it may be useful to evaluate additional alternative methods, such as pyrethrum spray catches and back packer aspirators, for catching resting mosquitoes

An affordable, quality-assured community-based system for high-resolution entomological surveillance of vector mosquitoes that reflects human malaria infection risk patterns.

ABSTRACT: BACKGROUND: More sensitive and scalable entomological surveillance tools are required to monitor low levels of transmission that are increasingly common across the tropics, particularly where vector control has been successful. A large-scale larviciding programme in urban Dar es Salaam, Tanzania is supported by a community-based (CB) system for trapping adult mosquito densities to monitor programme performance. Methodology An intensive and extensive CB system for routine, longitudinal, programmatic surveillance of malaria vectors and other mosquitoes using the Ifakara Tent Trap (ITT-C) was developed in Urban Dar es Salaam, Tanzania, and validated by comparison with quality assurance (QA) surveys using either ITT-C or human landing catches (HLC), as well as a cross-sectional survey of malaria parasite prevalence in the same housing compounds. RESULTS: Community-based ITT-C had much lower sensitivity per person-night of sampling than HLC (Relative Rate (RR) [95% Confidence Interval (CI)] = 0.079 [0.051, 0.121], P < 0.001 for Anopheles gambiae s.l. and 0.153 [0.137, 0.171], P < 0.001 for Culicines) but only moderately differed from QA surveys with the same trap (0.536 [0.406,0.617], P = 0.001 and 0.747 [0.677,0.824], P < 0.001, for An. gambiae or Culex respectively). Despite the poor sensitivity of the ITT per night of sampling, when CB-ITT was compared with QA-HLC, it proved at least comparably sensitive in absolute terms (171 versus 169 primary vectors caught) and cost-effective (153US$versus 187US$ per An. gambiae caught) because it allowed more spatially extensive and temporally intensive sampling (4284 versus 335 trap nights distributed over 615 versus 240 locations with a mean number of samples per year of 143 versus 141). Despite the very low vectors densities (Annual estimate of about 170 An gambiae s.l bites per person per year), CB-ITT was the only entomological predictor of parasite infection risk (Odds Ratio [95% CI] = 4.43[3.027,7. 454] per An. gambiae or Anopheles funestus caught per night, P =0.0373). Discussion and conclusion CB trapping approaches could be improved with more sensitive traps, but already offer a practical, safe and affordable system for routine programmatic mosquito surveillance and clusters could be distributed across entire countries by adapting the sample submission and quality assurance procedures accordingly

Entomological Surveillance of Behavioural Resilience and Resistance in Residual Malaria Vector Populations.

The most potent malaria vectors rely heavily upon human blood so they are vulnerable to attack with insecticide-treated nets (ITNs) and indoor residual spraying (IRS) within houses. Mosquito taxa that can avoid feeding or resting indoors, or by obtaining blood from animals, mediate a growing proportion of the dwindling transmission that persists as ITNs and IRS are scaled up. Increasing frequency of behavioural evasion traits within persisting residual vector systems usually reflect the successful suppression of the most potent and vulnerable vector taxa by IRS or ITNs, rather than their failure. Many of the commonly observed changes in mosquito behavioural patterns following intervention scale-up may well be explained by modified taxonomic composition and expression of phenotypically plastic behavioural preferences, rather than altered innate preferences of individuals or populations. Detailed review of the contemporary evidence base does not yet provide any clear-cut example of true behavioural resistance and is, therefore, consistent with the hypothesis presented. Caution should be exercised before over-interpreting most existing reports of increased frequency of behavioural traits which enable mosquitoes to evade fatal contact with insecticides: this may simply be the result of suppressing the most behaviourally vulnerable of the vector taxa that constituted the original transmission system. Mosquito taxa which have always exhibited such evasive traits may be more accurately described as behaviourally resilient, rather than resistant. Ongoing national or regional entomological monitoring surveys of physiological susceptibility to insecticides should be supplemented with biologically and epidemiologically meaningfully estimates of malaria vector population dynamics and the behavioural phenotypes that determine intervention impact, in order to design, select, evaluate and optimize the implementation of vector control measures

Factors influencing the level of preparedness to adopt IFRS 17 in insurance firms in Kenya

Full - text thesisFinancial reporting by insurance companies has been a challenge for a long time and the initial proposal was to have IFRS 4 provide minimal guidelines on these reporting complexities. After a long duration of stakeholder engagement, IFRS 17 came into effect in 2023 although it was approved for implementation in 2018 to assist in accounting and reporting critical issues in complex insurance contracts and features. However, in the close of the year 2023 only 14 insurance firms had fully adopted IFRS 17. The main question of the study therefore was why are insurance firms taking too long to fully adopt IFRS 17? What were the impending factors affecting the level of preparedness to adopt IFRS 17?.The drive of this study was therefore to assess factors influencing the level of preparedness to adopt IFRS 17 in insurance companies in Kenya and the specific objectives were to assess the effect of board characteristics on the level of preparedness to adopt IFRS 17, to establish the effect of financial metrics on the level of preparedness to adopt IFRS 17, to evaluate the effect of type of insurance business on the level of preparedness to adopt IFRS 17 and to establish management views on the challenges and strengths facing the level of preparedness to adopt IFRS 17 on Kenyan insurance companies. The organizational readiness for change theory and the absorptive capacity theory functioned as the study's guiding theories. The population of the study comprised of all 56 licensed insurance companies in Kenya regulated by the Insurance Regulatory Authority of Kenya. It was through structured surveys that primary data was gathered. Secondary data was taken from the Insurance Regulatory Authority’s annual published supervisory reports and insurance companies final financial statements using a data collection sheet covering the five-year period from 2018 to 2022.Panel data regression analysis, correlation analysis and descriptive statistics were used to analyze the data. Inferential results showed that taking all factors, ceteris paribus (solvency ratios, liquidity ratios, earnings ratios, profitability ratios, board size, board composition, number of females in the board, board independence and type of business) the level of preparedness to adopt IFRS 17 in insurance companies in Kenya would be 0.637. The data results analyzed also showed that the seven independent variables had a positive influence, while two had negative influence on the level of preparedness to adopt IFRS 17 in insurance companies in Kenya. Additionally, the ANOVA analysis showed a significant difference between the groups confirming that all the nine variables were fit in the regression equation. Findings also indicated that unit growths in the seven variables (solvency ratios, liquidity ratios, earnings ratios, profitability ratios, board size, board independence and female in the board) would result in a positive growth on the level of preparedness to adopt IFRS 17. On the contrary, a unit growth in board composition and type of business would result in a negative growth on the level of preparedness to adopt IFRS 17. The study recommendations will assist insurance firms in the process of full implementation and assist regulators in promoting stability without reducing size of the industry

The potential for sand dams to increase the adaptive capacity of East African drylands to climate change

Drylands are home to more than two billion people and are characterised by frequent, severe droughts. Such extreme events are expected to be exacerbated in the near future by climate change. A potentially simple and cost-effective mitigation measure against drought periods is sand dams. This little-known technology aims to promote subsoil rainwater storage to support dryland agro-ecosystems. To date, there is little long-term empirical analysis that tests the effectiveness of this approach during droughts. This study addresses this shortcoming by utilising multi-year satellite imagery to monitor the effect of droughts at sand dam locations. A time series of satellite images was analysed to compare vegetation at sand dam sites and control sites over selected periods of drought, using the normalised difference vegetation index. The results show that vegetation biomass was consistently and significantly higher at sand dam sites during periods of extended droughts. It is also shown that vegetation at sand dam sites recovers more quickly from drought. The observed findings corroborate modelling-based research which identified related impacts on ground water, land cover, and socio-economic indicators. Using past periods of drought as an analogue to future climate change conditions, this study indicates that sand dams have potential to increase adaptive capacity and resilience to climate change in drylands. It therefore can be concluded that sand dams enhance the resilience of marginal environments and increase the adaptive capacity of drylands. Sand dams can therefore be a promising adaptation response to the impacts of future climate change on drylands

Prevalence of abnormal cervical cytology among women infected with HIV in Machakos County Hospital Kenya

Background: Cervical cancer is increasingly becoming a major threat to health among women in the world particularly in developing countries where screening programs are not well established. In Kenya, cervical cancer is the second most frequent cancer among women and the leading cause of cancer deaths in women of reproductive age.Studies have shown that women infected with HIV especially those with low CD4 counts or decreasing immunity are at a higher risk of developing pre cancerous cervical lesions and invasive cervical cancer than those in the general population without HIV infection.Objective: To determine the prevalence of abnormal Pap smears in HIV positive women attending Comprehensive care clinic at Machakos Level 5 Hospital.Design: Cross sectional descriptive studySetting: Machakos County hospital.Subjects: Women infected with HIV attending Machakos County Hospital Comprehensive care clinic.Results: 295 women infected with HIV were enrolled in this study and cervical smear taken for cytology screening. 22 were excluded from the analysis due to unsatisfactory smears. The prevalence of cervical cytology abnormalities was 14 out of 273 (5.1%) with HSIL being the most prevalent at 5 out of 273 (1.8%). Other lesions were ASC-H 4 (1.46%), LSIL 3 (1.05%), SCC and Adenocarcinoma both with 1(0.36%).In this study, age and Pap smear findings had no statistically significant association, X²=6.262, p=0.618.Conclusion: This prevalence of abnormal cervical cytology among HIV infected women in this study was 5.2%. There was no statistically significant association between age and Pap smear findings

Mathematical Evaluation of Community Level Impact of Combining Bed Nets and Indoor Residual Spraying upon Malaria Transmission in Areas where the main Vectors are Anopheles Arabiensis Mosquitoes.

Indoor residual insecticide spraying (IRS) and long-lasting insecticide treated nets (LLINs) are commonly used together even though evidence that such combinations confer greater protection against malaria than either method alone is inconsistent. A deterministic model of mosquito life cycle processes was adapted to allow parameterization with results from experimental hut trials of various combinations of untreated nets or LLINs (Olyset, PermaNet 2.0, Icon Life nets) with IRS (pirimiphos methyl, lambda cyhalothrin, DDT), in a setting where vector populations are dominated by Anopheles arabiensis, so that community level impact upon malaria transmission at high coverage could be predicted. Intact untreated nets alone provide equivalent personal protection to all three LLINs. Relative to IRS plus untreated nets, community level protection is slightly higher when Olyset or PermaNet 2.0 nets are added onto IRS with pirimiphos methyl or lambda cyhalothrin but not DDT, and when Icon Life nets supplement any of the IRS insecticides. Adding IRS onto any net modestly enhances communal protection when pirimiphos methyl is sprayed, while spraying lambda cyhalothrin enhances protection for untreated nets but not LLINs. Addition of DDT reduces communal protection when added to LLINs. Where transmission is mediated primarily by An. arabiensis, adding IRS to high LLIN coverage provides only modest incremental benefit (e.g. when an organophosphate like pirimiphos methyl is used), but can be redundant (e.g. when a pyrethroid like lambda cyhalothin is used) or even regressive (e.g. when DDT is used for the IRS). Relative to IRS plus untreated nets, supplementing IRS with LLINs will only modestly improve community protection. Beyond the physical protection that intact nets provide, additional protection against transmission by An. arabiensis conferred by insecticides will be remarkably small, regardless of whether they are delivered as LLINs or IRS. The insecticidal action of LLINs and IRS probably already approaches their absolute limit of potential impact upon this persistent vector so personal protection of nets should be enhanced by improving the physical integrity and durability. Combining LLINs and non-pyrethroid IRS in residual transmission systems may nevertheless be justified as a means to manage insecticide resistance and prevent potential rebound of not only An. arabiensis, but also more potent, vulnerable and historically important species such as Anopheles gambiae and Anopheles funestus

Geographic Coincidence of Increased Malaria Transmission Hazard and Vulnerability Occurring at the Periphery of two Tanzanian Villages.

The goal of malaria elimination necessitates an improved understanding of any fine-scale geographic variations in transmission risk so that complementary vector control tools can be integrated into current vector control programmes as supplementary measures that are spatially targeted to maximize impact upon residual transmission. This study examines the distribution of host-seeking malaria vectors at households within two villages in rural Tanzania. Host-seeking mosquitoes were sampled from 72 randomly selected households in two villages on a monthly basis throughout 2008 using CDC light-traps placed beside occupied nets. Spatial autocorrelation in the dataset was examined using the Moran's I statistic and the location of any clusters was identified using the Getis-Ord Gi* statistic. Statistical associations between the household characteristics and clusters of mosquitoes were assessed using a generalized linear model for each species. For both Anopheles gambiae sensu lato and Anopheles funestus, the density of host-seeking females was spatially autocorrelated, or clustered. For both species, houses with low densities were clustered in the semi-urban village centre while houses with high densities were clustered in the periphery of the villages. Clusters of houses with low or high densities of An. gambiae s.l. were influenced by the number of residents in nearby houses. The occurrence of high-density clusters of An. gambiae s.l. was associated with lower elevations while An. funestus was also associated with higher elevations. Distance from the village centre was also positively correlated with the number of household occupants and having houses constructed with open eaves. The results of the current study highlight that complementary vector control tools could be most effectively targeted to the periphery of villages where the households potentially have a higher hazard (mosquito densities) and vulnerability (open eaves and larger households) to malaria infection

HPV DNA testing and pap smear cytology co-testing as a‘test of cure’ in patients previously treated for cervical lesions by leep at Kenyatta National Hospital

Background: HPV infection is a pre-requisite for the development of the majority (99.7%) of precancerous cervical lesions. Treatment of cervical precancerous lesions reduces the risk of invasive cervical cancer by 90%; however, treated women still have five times risk of invasive cancer compared to women who have  always had a normal Pap smear, thus special follow-up measures are critical to reduce these risks.Objective: To determine the utility of co-testing by conventional Pap smear and HPV testing as a ‘test of cure’ in patients previously treated for cervical lesions by LEEP at KNH.Design: Cross sectional descriptive study.Setting: Kenyatta National Hospital and KAVI molecular laboratory.Subjects: Women on follow for cervical lesions post LEEP treatment.Results: Out of the 25 participants, 22(88%) had a report of NILM while 3(12%) had a report of ≥ASCUS). 16 (64%) were positive for HPV. HPV 56 was the commonest HPV subtype detected in 11 patients (41%). The Cohen’s Kappa correlation between Pap smear and HPV DNA test not statistically significant = 0.143, 95% CI: -0.17 to 0.46, p=0. 166.There was no statistically significant association between HIV status and pap smear findings post LEEP, X²=0.711, p=0.399Conclusions: Co-testing with HPV DNA testing and Pap smear is a useful approach to stratify women with no cytological abnormalities according to their risk of residual diseas

Eliminating Malaria Vectors.

Malaria vectors which predominantly feed indoors upon humans have been locally eliminated from several settings with insecticide treated nets (ITNs), indoor residual spraying or larval source management. Recent dramatic declines of An. gambiae in east Africa with imperfect ITN coverage suggest mosquito populations can rapidly collapse when forced below realistically achievable, non-zero thresholds of density and supporting resource availability. Here we explain why insecticide-based mosquito elimination strategies are feasible, desirable and can be extended to a wider variety of species by expanding the vector control arsenal to cover a broader spectrum of the resources they need to survive. The greatest advantage of eliminating mosquitoes, rather than merely controlling them, is that this precludes local selection for behavioural or physiological resistance traits. The greatest challenges are therefore to achieve high biological coverage of targeted resources rapidly enough to prevent local emergence of resistance and to then continually exclude, monitor for and respond to re-invasion from external populations