moses zimba

Field studies were conducted in villages near the peri urban Dema area, Seke district, Zimbabwe, in order to understand the effect of the insecticides fenitrothion and lindane on Periplaneta americana and Blattella germanica cockroaches. A total of 63, 72 and 71 rooms were used for control, fenitrothion and lindane respectively. The mean density per room for P. americana before spraying was 43.5, 42.7 and 44.1 for the control, fenitrothion and lindane respectively. The mean density per room for B. germanica before spraying was 51.4, 50.2 and 47.1 for the control, fenitrothion and lindane respectively. A reduction in population density of P. americana was 3.2%, 83.8% and 99.3% in the control, fenitrothion and lindane rooms respectively. A reduction in population density of B. germanica was 87.8% and 82.8% in fenitrothion and lindane rooms respectively. An increase of 9.9% in the control rooms was observed. The majority of P. americana cockroaches died one month post spray with fenitr...

Regular entomological monitoring is important to determine changes in mosquito species composition and relative densities of malaria vectors in relation to vector control interventions. A study to gain insights into malaria vector species composition and relative abundance was undertaken in Mutare and Mutasa districts, Zimbabwe. Two methods; indoor resting catches and larval sampling were used to collect indoor resting adults and larvae from May 2013 to April 2014. Mosquitoes collected as adults and reared from larvae that were identified morphologically as potential malaria vectors were further processed to sibling species by polymerase chain reaction (PCR). Morphological identification of anopheline mosquitoes showed presence of two complexes: <em>An. funestus</em> and <em>An. gambiae</em>. The total number of female members of the <em>An. funestus</em> group and <em>An. gambiae</em> complex collected by both methods from the two sit...

Multidrug-resistant tuberculosis (MDR-TB) is among the most worrisome aspects of the pandemic of antibiotic resistance because TB patients that fail treatment have a high risk of death.  The active multidrug efflux pump (EP) has been described as one of the mechanisms involved in the natural drug resistance of bacteria, such as mycobacteria. Rv1819c a putative efflux pump ATP binding cassette (ABC) protein gene from Mycobacterium tuberculosis , was cloned and transformed into Corynebacterium glutamicum. Susceptibility to standard anti-TB drugs and purified plant compounds, in the presence or absence of standard efflux pump inhibitors (EPIs), carbonyl cyanide m-chlorophenylhydrazone (CCCP), reserpine and verapamil) was determined. A fluorometric method was used to assess the ability of the purified plant compounds to inhibit efflux pumps in comparison with three standard EPIs: reserpine, verapamil, and CCCP. Three of the plant compounds coded Ma8, IXLE1B and IXLE2FA were found to hav...

Objectives: Interest in mycobacterial persistence is rising, stemming from the current TB drugs being inadequate at killing dormant or persistent tubercle bacilli resulting in a lengthy chemotherapy. This study hypothesized that efflux pumps could be a risk factor to TB persistence, such that TB bacilli are not rapidly cleared during the intensive phase of treatment. Methodology and Results: M. tuberculosis isolates from patients whose sputum smear had remained positive despite being subjected to two months intensive phase of TB treatment were employed as cases in this study. Isolates from patients who successfully seroconverted to negative sputum smear were the controls. An investigation was done on whether Rv1819c efflux pump gene expression and its correlation with the cell’s ability to efflux ethidium bromide (a common efflux substrate) is associated with clinical persistence of TB bacilli. Efflux pump gene expression differed significantly between the treatment failures and tre...

Abstract A study was conducted to investigate the current resting behavior of malaria vectors in Mutare and Mutasa districts, Zimbabwe. Mosquitoes were captured using pyrethrum spray collection, prokopac aspirator, pit shelter, and exit trap methods. Mosquitoes were sorted and identified using morphological key and polymerase chain reaction (PCR) techniques. The Anopheles funestus group constituted 97%, whereas Anopheles gambiae complex mosquitoes were few (3%). Endophilic collections in both species were five times greater than exophilic catches. The endophilic trait was further demonstrated by gravid to fed index (gravid/fed) of constantly more than 1. Nearly 90% endophilic An. funestus populations were collected on sprayable and 10% collected on unsprayable surfaces. Of the sprayable surfaces, 56% were collected on the roofs, with 44% on the walls. Of those on the walls, 44, 22, and 34% were caught on wall heights >1, 1.0–1.5, <1.5 m from the ground, respectively. Of the gravid An. funestus caught, nearly two-thirds were collected exiting pyrethroid-treated structures, with a 24-h mortality of less than 10%. The PCR analysis of 120 specimens taken randomly from the An. funestus group was all An. funestus s.s. The present work indicates that for effective malaria control in Mutare and Mutasa districts using indoor residual spraying, both walls and roofs must be sprayed.

Insecticide resistance in major malaria vectors poses severe challenges for stakeholders responsible for controlling the disease. During the 2013/14 season, malaria vector sentinel sites in Mutare and Mutasa Districts, Zimbabwe, experienced high presence of gravid malaria vector mosquitoes resting indoors in recently pyrethroid-sprayed structures. Subsequently, an evaluation of insecticide resistance in Anopheles funestus populations, the major malaria vector, was conducted to better inform the Zimbabwe National Malaria Control Programme. Indoor-resting mosquitoes were collected in randomly selected pyrethroid-sprayed houses around Burma Valley and Zindi sentinel sites in Mutare and Mutasa Districts, respectively, using prokopac aspirator in February 2014. A. funestus mosquitoes were identified in the field using morphological keys and divided into two cohorts. One cohort was used immediately for WHO susceptibility tests and the other batch was transferred to the National Institute ...

The present study describes and evaluates a new tool for disinfesting maize grain from weevils using heat from boiling water. In developing countries, rural farmers lose huge amounts of grain due to weevils. Cost of insecticides and resistance of grain weevils to current insecticides are major threats. The grain losses affect the nutritional status and general quality of life of rural communities. Most grain is infested by weevils while in the field before harvest, therefore disinfestation of grain before storage is crucial. The equipment was made from 0.3 mm galvanized sheets and consisted of an inner pot for holding grain, outer pot for boiling water and a two litre metal cup. The most common maize variety grown in Zimbabwe, infested predominantly with Prostephanus truncatus and Sitophilus zeamais was used to evaluate the equipment. Empty maize cobs (after removing the grain) were used as source of heat. The equipment achieved 100% mortality of both species of weevils at 48°C (whe...

Rift Valley Fever (RVF) is an emerging disease threatening human and livestock health in Africa and the Middle-East. The role of wildlife in the maintenance and transmission of the virus at human/livestock/wildlife interfaces in Southern Africa remains unclear. In order to elucidate RVF epidemiology in the Great Limpopo (GLTFCA) and the Kavango-Zambezi (KAZATFCA), we combined preliminary data from serology, entomology, telemetry and field experiments in Zimbabwe. Methods: At each site, blood samples were taken between 2008 and 2011 from livestock and buffalo. The samples were tested with I-ELISA for RVF antibodies and the data analysed with Generalized Linear Model. Four mosquito trapping sessions were conducted at water holes used by livestock and/or wildlife. Potential contacts between wildlife and cattle were assessed using data of GPS collared cattle and buffalo published elsewhere. Bags of viscera were used as a proxy to estimate residence time of aborted fetus and potential in...

Background This paper outlines Zimbabwe’s potential readiness in harnessing integrated vector management (IVM) strategy for enhanced control of vector-borne diseases. The objective is to provide guidance for the country in the implementation of the national IVM strategy in order to make improvements required in thematic areas of need. The paper also assesses the existing opportunities and gaps to promote and adopt the approach as a national policy. Main text Despite recent gains in combating vector-borne diseases, especially malaria, management of vector control programmes still remains insecticide-based and vertical in nature. Therefore, concerns have been raised on whether the current long-standing conventional vector control strategy still remains with sufficient action to continue to break the transmission cycle to the levels of elimination. This is so, given the continuous dwindling resources for vector control, changes in vector behaviour, the emergence of resistance to medici...

In 2014, we carried out a survey in Chinamhora and Chihota communal lands on the outskirts of Harare city, with the aim of understanding pesticide management practices among market gardening farmers. The farmers grew vegetables that mostly included tomatoes, cabbages, rape, cucumbers, onions and carrots, and they used mainly organophosphates and pyrethroids to control pests. A questionnaire was administered to 119 male heads of households across both study areas. The questionnaire contained 13 closed-ended questions in three sections: source and quality of pesticides, handling and use, and storage and disposal of pesticides used to protect crops. The study identified numerous gaps related to the handling of pesticides. Although the quality of labelling and packaging can largely identify the quality of pesticide, most of the farmers (77.3%) could not distinguish between genuine and counterfeit pesticides; approximately half (47.9%) of the farmers were not concerned about expiry dates...

Biting behaviour of Anopheles funestus in Mutare and Mutasa districts, Zimbabwe, is little understood. An investigation was conducted to primarily compare indoor and outdoor biting behaviour of the mosquito, as well as blood meal sources and sporozoite rates. Monthly adult anopheline sampling was conducted from October 2013 to September 2014 using Centers for Disease Control light-traps, pyrethrum spray catch and artificial pit shelter methods. Mosquitoes sampled by light-traps were divided into two cohorts. In one cohort, traps were left overnight and mosquitoes were collected the following morning, while in the other set, mosquitoes were collected hourly from 1800-0600 hrs . Collected females were identified using morphological characters and categorised according to their abdominal status. Polymerase chain reaction was used to identify An. funestus sibling species and blood meal sources. Infection rate was tested by enzyme-linked immunosorbent assay. Morphological identification ...

The study was aimed at determining the seasonal abundance of Xenopsylla brasiliensis, an important vector of plague in Zimbabwe, from rodent hosts captured in selected habitat types of two periurban suburbs of Harare, Zimbabwe. The removal-trapping method was used to capture the rodents, from which fleas were collected and identified. Percentage incidence index (PII) and specific flea index (SFI) were calculated for X. brasiliensis in relation to rodent species host. Mastomys natalensis, Rattus rattus, Tatera leucogaster, and Rhabdomys pumilio were the rodent species present in the study areas and all species were infested with X. brasiliensis. PII for T. leucogaster in relation to X. brasiliensis was significantly higher (p < 0.05) compared with that of the other rodent species and T. leucogaster also recorded the highest SFI, whereas R. pumilio recorded the lowest indices. In both formal and informal settlements, the highest PII of X. brasiliensis was attained for M. natalensis, followed by R. rattus. In the cultivated habitat, T. leucogaster recorded the highest indices and R. pumilio the lowest. X. brasiliensis was found to cohabitat with Dinopsyllus lypusus and Ctenophthalmus calceatus on M. natalensis, R. rattus, and T. leucogaster. No cohabitation was recorded for R. pumilio. For all the rodent species captured, both the PII and SFI of X. brasiliensis were highest during the hot-dry season, followed by the hot-wet season, with the cold-dry season recording the lowest indices. The overall cohabitation was highest during the hot-dry season and lowest during the hot-wet season. The findings of the present study fit the reported occurrence of plague outbreaks during the hot-dry season in periurban Zimbabwe.

The seasonal abundance of Dinopsyllus lypusus Jordan and Rothschild and Ctenophthalmus calceatus Waterson (potential vectors of plague in southern Africa) were studied on rodent hosts captured in selected habitat types of two periurban suburbs of Harare, Zimbabwe. Removal trapping was used to capture the rodents, from which fleas were collected and identified. Prevalence (proportion of animals infested) and specific flea index (SFI = number of fleas per animal) were calculated for each species of rodent host. Cohabitation of the two flea species on the host and its implications were also assessed. In total, 1,083 rodents belonging to nine species were trapped and over 97% of the total captures comprised of four species; Mastomys natalensis Smith, Rattus rattus L., Tatera leucogaster Peters, and Rhabdomys pumilio Sparrman. In total, 735 D. lypusus and 335 C. calceatus were recorded on these four common rodent species. Population density of D. lypusus as measured by prevalence and SFI varied from 13.4 to 53.3% and 0.2-1.5, respectively, while that of C. calceatus varied from 8.2 to 26.7% and 0.2-0.6, respectively. For all rodent species captured, both prevalence and SFI of D. lypusus and C. calceatus were highest during the cold-dry season, followed by the hot dry season, with the hot-wet season recording the lowest indices. Overall cohabitation was highest during the cold-dry season and nonexistent during the hot-wet season. Our findings on the abundance and ecology of D. lypusus and C. calceatus suggest that their roles in the transmission of plague in Zimbabwe need further investigation.