\ud Detection and Monitoring of Insecticide Resistance in Malaria Vectors in Tanzania Mainland\ud

\ud Vector control is a major component of the global strategy for malaria control which aims to prevent parasite transmission mainly through interventions targeting adult Anopheline vectors. Insecticide treated nets (ITNs) and indoor residual spraying (IRS) are the cornerstone of malaria vector control programmes. These major interventions in most cases use pyrethroid insecticides which are also used for agricultural purposes. With widespread development of resistance to pyrethroid insecticides in malaria vectors raises concern over the sustainability of insecticide-based interventions for malaria control. Therefore, close monitoring of performance of the insecticides against malaria vectors is essential for early detection and\ud management of resistance. To measure pyrethroid susceptibility in populations of malaria vectors in Tanzania and to test the efficacy of LLINs/ITNs and insecticide residues on sprayed wall substrates in the IRS operation areas. In 2011 the National Institute for Medical Research (NIMR) in collaboration with National Malaria Control Programme (NMCP) conducted large scale surveillance to determine the countrywide susceptibility levels of malaria vectors to insecticides used for both public health and agricultural purposes. Anopheles gambiae Giles s.l. were collected during national surveys and samples of LLINs/ITNs in the 14 sentinel sites and houses from the IRS areas were randomly selected for bioassays to test the efficacy and insecticide residual effects on sprayed wall substrates respectively. Wild adult mosquitoes for susceptibility testing were collected by resting catches indoors. Net traps (outdoors and indoors) were set up to enhance catches. WHO Susceptibility kits were used to test for resistance status using test papers: Lambdacyhalothrin 0.05%, Deltamethrin 0.05%, Permethrin 0.75%, DDT 4%, Propoxur 0.1% and Fenitrothion 1%. The quality of the test paper was checked against a laboratory susceptible An. gambiae Kisumu strain. Knockdown effect and mortality were measured in standard WHO susceptibility tests and cone bio-efficacy tests. Whereas, con bioassays on treated walls and ITNs were conducted using the laboratory susceptible An. gambiae Kisumu strain. The results from the surveillance recorded continued susceptibility of malaria vectors to commonly used insecticides. However, there were some isolated cases of resistance and/or reduced susceptibility to pyrethroid insecticides which may not compromise the current vector control interventions in the country. Anopheles gambiae s.l. showed resistance (15-28%) to each of the pyrethroids and to DDT but not to Organophosphates (Propoxur 0.1%), and Carbamates (Fenitrothion 1%). The information obtained from this surveillance is expected to be used to guide the National Malaria Control Programme on the rational selection of insecticides for malaria vector control and for the national mitigation plans for management and containment of malaria vector resistance in the country. The current observation warrants more vigilant monitoring of the susceptibility of malaria mosquitoes to commonly used insecticides in areas found with resistance and/or reduced levels of susceptibility of malaria vectors to insecticides, particularly in areas with heavy agricultural and/or public health use of insecticides where resistance is likely to develop. The current survey covered malaria vectors only and not the non malaria vectors (nuisance) mosquitoes such as Culex. Similar monitoring of insecticide susceptibility of this non malaria vectors may be needed to ensure public motivation for sustained use of ITNs/LLINs in the country. The surveillance leading to these results received funding from PMI/USAID through RTI International with Sub Agreement Number 33300212555.\u

Tumour-associated immune responses and isolated carcinoembryonic antigen and alpha feto-protein levels related to survival in ovarian cancer patients.

The presence of a tumour-associated immune response in 37 patients with ovarian cancer as assessed by blastogenesis (lymphocyte transformation) evoked by ovarian cancer cell extracts, has been correlated with survival following the test. The difference in these responses is unlikely to be accounted for on the basis of general impairment of cell-mediated immuno-competence. Serum carcinoembryonic antigen (CEA) was also determined in 27 ovarian cancer patients to assess its prognostic significance. Raised CEA levels and absence of blastogenic response to tumour cell extract during relapse are associated with a worse prognosis but neither of these parameters are significant in remission. Possible applications of these findings to the clinical management of ovarian cancer patients are discussed. Serum alpha feto-protein levels measured by radioimmunoassay were not found to be raised in any of the 32 ovarian cancer patients in whom it was measured

Causes of death and associated factors over a decade of follow-up in a cohort of people living with HIV in rural Tanzania

BACKGROUND: Nearly half of HIV-related deaths occur in East and Southern Africa, yet data on causes of death (COD) are scarce. We determined COD and associated factors among people living with HIV (PLHIV) in rural Tanzania. METHODS: PLHIV attending the Chronic Diseases Clinic of Ifakara, Morogoro are invited to enrol in the Kilombero and Ulanga Antiretroviral Cohort (KIULARCO). Among adults (>/= 15 years) enrolled in 2005-2018, with follow-up through April 2019, we classified COD in comprehensive classes and as HIV- or non-HIV-related. In the subset of participants enrolled in 2013-2018 (when data were more complete), we assessed cause-specific mortality using cumulative incidences, and associated factors using proportional hazards models. RESULTS: Among 9871 adults (65% female, 26% CD4 count < 100 cells/mm(3)), 926 (9%) died, among whom COD were available for 474 (51%), with missing COD mainly in earlier years. The most common COD were tuberculosis (N = 127, 27%), non-AIDS-related infections (N = 72, 15%), and other AIDS-related infections (N = 59, 12%). Cardiovascular and renal deaths emerged as important COD in later calendar years, with 27% of deaths in 2018 attributable to cardiovascular causes. Most deaths (51%) occurred within the first six months following enrolment. Among 3956 participants enrolled in 2013-2018 (N = 203 deaths, 200 with COD ascertained), tuberculosis persisted as the most common COD (25%), but substantial proportions of deaths from six months after enrolment onwards were attributable to renal (14%), non-AIDS-related infections (13%), other AIDS-related infections (10%) and cardiovascular (10%) causes. Factors associated with higher HIV-related mortality were sex, younger age, living in Ifakara town, HIV status disclosure, hospitalisation, not being underweight, lower CD4 count, advanced WHO stage, and gaps in care. Factors associated with higher non-HIV-related mortality included not having an HIV-positive partner, lower CD4 count, advanced WHO stage, and gaps in care. CONCLUSION: Incidence of HIV-related mortality was higher than that of non-HIV-related mortality, even in more recent years, likely due to late presentation. Tuberculosis was the leading specific COD identified, particularly soon after enrolment, while in later calendar years cardiovascular and renal causes emerged as important, emphasising the need for improved screening and management

Stigma-directed services (Stig2Health) to improve 'linkage to care' for people living with HIV in rural Tanzania: study protocol for a nested pre-post implementation study within the Kilombero and Ulanga Antiretroviral Cohort

Background: HIV-related stigma is a major barrier to the timely linkage and retention of patients in HIV care in sub-Saharan Africa, where most people living with HIV/AIDS reside. In this implementation study we aim to evaluate the effect of stigma-directed services on linkage to care and other health outcomes in newly diagnosed HIV-positive patients. Methods: In a nested project of the Kilombero and Ulanga Antiretroviral Cohort in rural Tanzania, we conduct a prospective observational pre-post study to assess the impact of a bundle of stigma-directed services for newly diagnosed HIV positive patients. Stigma-directed services, delivered by a lay person living with HIV, are i) post-test counseling, ii) post-test video-assisted teaching, iii) group support therapy and group health education, and iv) mobile health. Patients receiving stigma services (enrolled from 1 (st) February 2020 to 31 (st) August 2021) are compared to a historical control receiving the standard of care (enrolled from 1 (st) July 2017 to 1 (st) February 2019). The primary outcome is 'linkage to care'. Secondary endpoints are retention in care, viral suppression, death and clinical failure at 6-12 months (up to 31 (st) August 2022). Self-reported stigma and depression are assessed using the Berger Stigma scale and the PHQ-9 questionnaire, respectively. The sample size calculation was based on cohort data from 2018. Assuming a pre-intervention cohort of 511 newly diagnosed adults of whom 346 (68%) were in care and on antiretroviral treatment (ART) at 2 months, a 10% increase in linkage (from 70 to 80%), a two-sided type I error rate of 5%, and 90% power, 321 adults are required for the post-implementation group. Discussion: We expect that integration of stigma-directed services leads to an increase of proportions of patients in care and on ART. The findings will provide guidance on how to integrate stigma-directed services into routine care in rural sub-Saharan Africa

Predicting Distribution of Aedes Aegypti and Culex Pipiens Complex, Potential Vectors of Rift Valley Fever Virus in Relation to Disease Epidemics in East Africa.

The East African region has experienced several Rift Valley fever (RVF) outbreaks since the 1930s. The objective of this study was to identify distributions of potential disease vectors in relation to disease epidemics. Understanding disease vector potential distributions is a major concern for disease transmission dynamics. DIVERSE ECOLOGICAL NICHE MODELLING TECHNIQUES HAVE BEEN DEVELOPED FOR THIS PURPOSE: we present a maximum entropy (Maxent) approach for estimating distributions of potential RVF vectors in un-sampled areas in East Africa. We modelled the distribution of two species of mosquitoes (Aedes aegypti and Culex pipiens complex) responsible for potential maintenance and amplification of the virus, respectively. Predicted distributions of environmentally suitable areas in East Africa were based on the presence-only occurrence data derived from our entomological study in Ngorongoro District in northern Tanzania. Our model predicted potential suitable areas with high success rates of 90.9% for A. aegypti and 91.6% for C. pipiens complex. Model performance was statistically significantly better than random for both species. Most suitable sites for the two vectors were predicted in central and northwestern Tanzania with previous disease epidemics. Other important risk areas include western Lake Victoria, northern parts of Lake Malawi, and the Rift Valley region of Kenya. Findings from this study show distributions of vectors had biological and epidemiological significance in relation to disease outbreak hotspots, and hence provide guidance for the selection of sampling areas for RVF vectors during inter-epidemic periods

Long-Lasting Control of Anopheles arabiensis by a Single Spray Application of Micro-encapsulated Pirimiphos-methyl (Actellic(R) 300 CS).

Pyrethroid-resistant mosquitoes are an increasing threat to malaria vector control. The Global Plan for Insecticide Resistance Management (GPIRM) recommends rotation of non-pyrethroid insecticides for indoor residual spraying (IRS). The options from other classes are limited. The carbamate bendiocarb and the organophosphate pirimiphos-methyl (p-methyl) emulsifiable concentrate (EC) have a short residual duration of action, resulting in increased costs due to multiple spray cycles, and user fatigue. Encapsulation (CS) technology was used to extend the residual performance of p-methyl. Two novel p-methyl CS formulations were evaluated alongside the existing EC in laboratory bioassays and experimental hut trials in Tanzania between 2008-2010. Bioassays were carried out monthly on sprayed substrates of mud, concrete, plywood, and palm thatch to assess residual activity. Experimental huts were used to assess efficacy against wild free-flying Anopheles arabiensis, in terms of insecticide-induced mortality and blood-feeding inhibition. In laboratory bioassays of An. arabiensis and Culex quinquefasciatus both CS formulations produced high rates of mortality for significantly longer than the EC formulation on all substrates. On mud, the best performing CS killed >80% of An. arabiensis for five months and >50% for eight months, compared with one and two months, respectively, for the EC. In monthly bioassays of experimental hut walls the EC was ineffective shortly after spraying, while the best CS formulation killed more than 80% of An. arabiensis for five months on mud, and seven months on concrete. In experimental huts both CS and EC formulations killed high proportions of free-flying wild An. arabiensis for up to 12 months after spraying. There was no significant difference between treatments. All treatments provided considerable personal protection, with blood-feeding inhibition ranging from 9-49% over time. The long residual performance of p-methyl CS was consistent in bioassays and experimental huts. The CS outperformed the EC in laboratory and hut bioassays but the EC longevity in huts was unexpected. Long-lasting p-methyl CS formulations should be more effective than both p-methyl EC and bendiocarb considering a single spray could be sufficient for annual malaria control. IRS with p-methyl 300 CS is a timely addition to the limited portfolio of long-lasting residual insecticides

Malaria elimination in Zanzibar: where next?

In 2018, Zanzibar developed a national malaria strategic plan IV (2018-2023) to guide elimination of malaria by 2023. We assessed progress in the implementation of malaria activities as part of the end-term review of the strategic plan. The review was done between August and October 2022 following the WHO guideline to assess progress made towards malaria elimination, effectiveness of the health systems in delivering malaria case management; and malaria financing. A desk review examined available malaria data, annual work plans and implementation reports for evidence of implemented malaria activities. This was complemented by field visits to selected health facilities and communities by external experts, and interviews with health management teams and inhabitants to authenticate desk review findings. A steady increase in the annual parasite incidence (API) was observed in Zanzibar, from 2.7 (2017) to 3.6 (2021) cases per 1,000 population with marked heterogeneity between areas. However, about 68% of the detected malaria cases were imported into Zanzibar. Malaria case follow-up and investigation increased from <70% in 2017 to 94% and 96% respectively, in 2021. The review noted a 3.7-fold increase of the health allocation in the country's budget, from 31.7 million USD (2017/18) to 117.3 million USD (2022/23) but malaria allocation remained low (<1%). The varying transmission levels in the islands suggest a need for strategic re-orientation of the elimination attempts from a national-wide to a sub-national agenda. We recommend increasing malaria allocation from the health budget to ensure sustainability of malaria elimination interventions

Comparative Field Evaluation of Combinations of Long-Lasting Insecticide Treated Nets and Indoor Residual Spraying, Relative to Either Method Alone, for Malaria Prevention in an Area where the main Vector is Anopheles Arabiensis.

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used together in the same households to improve malaria control despite inconsistent evidence on whether such combinations actually offer better protection than nets alone or IRS alone. Comparative tests were conducted using experimental huts fitted with LLINs, untreated nets, IRS plus untreated nets, or combinations of LLINs and IRS, in an area where Anopheles arabiensis is the predominant malaria vector species. Three LLIN types, Olyset®, PermaNet 2.0® and Icon Life® nets and three IRS treatments, pirimiphos-methyl, DDT, and lambda cyhalothrin, were used singly or in combinations. We compared, number of mosquitoes entering huts, proportion and number killed, proportions prevented from blood-feeding, time when mosquitoes exited the huts, and proportions caught exiting. The tests were done for four months in dry season and another six months in wet season, each time using new intact nets. All the net types, used with or without IRS, prevented >99% of indoor mosquito bites. Adding PermaNet 2.0® and Icon Life®, but not Olyset® nets into huts with any IRS increased mortality of malaria vectors relative to IRS alone. However, of all IRS treatments, only pirimiphos-methyl significantly increased vector mortality relative to LLINs alone, though this increase was modest. Overall, median mortality of An. arabiensis caught in huts with any of the treatments did not exceed 29%. No treatment reduced entry of the vectors into huts, except for marginal reductions due to PermaNet 2.0® nets and DDT. More than 95% of all mosquitoes were caught in exit traps rather than inside huts. Where the main malaria vector is An. arabiensis, adding IRS into houses with intact pyrethroid LLINs does not enhance house-hold level protection except where the IRS employs non-pyrethroid insecticides such as pirimiphos-methyl, which can confer modest enhancements. In contrast, adding intact bednets onto IRS enhances protection by preventing mosquito blood-feeding (even if the nets are non-insecticidal) and by slightly increasing mosquito mortality (in case of LLINs). The primary mode of action of intact LLINs against An. arabiensis is clearly bite prevention rather than insecticidal activity. Therefore, where resources are limited, priority should be to ensure that everyone at risk consistently uses LLINs and that the nets are regularly replaced before being excessively torn. Measures that maximize bite prevention (e.g. proper net sizes to effectively cover sleeping spaces, stronger net fibres that resist tears and burns and net use practices that preserve net longevity), should be emphasized

Indoor application of attractive toxic sugar bait (ATSB) in combination with mosquito nets for control of pyrethroid-resistant mosquitoes.

BACKGROUND: Attractive toxic sugar bait (ATSB) sprayed onto vegetation has been successful in controlling Anopheles mosquitoes outdoors. Indoor application of ATSB has yet to be explored. The purpose of this study was to determine whether ATSB stations positioned indoors have the potential to kill host-seeking mosquitoes and constitute a new approach to control of mosquito-borne diseases. METHODS: Insecticides were mixed with dyed sugar solution and tested as toxic baits against Anopheles arabiensis, An. Gambiae s.s. and Culex quinquefasciatus in feeding bioassay tests to identify suitable attractant-insecticide combinations. The most promising ATSB candidates were then trialed in experimental huts in Moshi, Tanzania. ATSB stations were hung in huts next to untreated mosquito nets occupied by human volunteers. The proportions of mosquitoes killed in huts with ATSB treatments relative to huts with non-insecticide control treatments huts were recorded, noting evidence of dye in mosquito abdomens. RESULTS: In feeding bioassays, chlorfenapyr 0.5% v/v, boric acid 2% w/v, and tolfenpyrad 1% v/v, mixed in a guava juice-based bait, each killed more than 90% of pyrethroid-susceptible An. Gambiae s.s. and pyrethroid-resistant An. arabiensis and Cx. quinquefasciatus. In the hut trial, mortality rates of the three ATSB treatments ranged from 41-48% against An. arabiensis and 36-43% against Cx. quinquefasciatus and all were significantly greater than the control mortalities: 18% for An. arabiensis, 7% for Cx. quinquefasciatus (p<0.05). Mortality rates with ATSB were comparable to those with long lasting insecticidal nets previously tested against the same species in this area. CONCLUSIONS: Indoor ATSB shows promise as a supplement to mosquito nets for controlling mosquitoes. Indoor ATSB constitute a novel application method for insecticide classes that act as stomach poisons and have not hitherto been exploited for mosquito control. Combined with LLIN, indoor use of ATSB has the potential to serve as a strategy for managing insecticide resistance