Vector species and Infectivity
The baseline survey of mosquito vectors in Gaza province showed large variations in mosquito numbers and species composition between zones. The baseline indicated that Anopheles funestus was the main vector, and An. arabiensis was a secondary vector.
The infectivity of mosquitoes provides a good image of disease transmission in an area. A baseline infectivity study in Gaza showed that 2.73% of mosquitoes were infected with Plasmodium falciparum. Studies subsequent to intervention measures have shown that none of the mosquitoes collected in window exit traps were infected which is indicative of low levels of transmission.
Indoor Residual Spraying (IRS)
Vector control interventions in the form of indoor residual spraying (IRS) of houses have to date been implemented in zones 4, 5 and 6. Implementation in Zone 7 will commence in the second halve of 2009. Insecticides applied on traditional structures were DDT and on brick, cement and painted structures Carbamates and Pyrethroids were used. Spraying are conducted using Hudson expert pumps with HSS8002E (DDT) and HSS8001E (carbamates & other) nozzles Application rate was 2 g·m2 for DDT, 400 mg·m2 for Ficam (carbamate) and 20-25 mg·m2 for Tanga and K Othrine (pyrethroids).
All spraying personnel and managers were provided with adequate training before the start of each round of spraying. Training was conducted at the training camp that was set up at Macarratane. To facilitate the spray process and to reduce costs, community involvement was established through the recruitment of spray operators from the local communities.
During the 2007/2008 malaria spray season, 348 spraymen have been trained, and in the 2008/2009 season number increased to 470 spraymen, half of which were new recruits with no previous training. The number of structures sprayed by the spraymen from 2006 to 2008 is shown below.
Number of structures sprayed per year in Gaza province under the indoor residual spraying programme of the LSDI initiative.
In line with the expansion of the spraying programme in the different zones of Gaza province, there was a significant increase in the number of structures sprayed from 2006 to 2007. In the 2008 spraying season, there was a marked decrease in the number of structures sprayed which is a direct result of financial constraints suffered by the LSDI in Gaza due to a delay in the release and transfer of funds by the Global Fund.
Quality control
A quality control visit was conducted from 15 – 18 January 2008 by Mr A. Mabuza (Mpumalanga Provincial Malaria Control Programme) and Mr. Q.E. Mabunda (Assistant Provincial Malaria Control Manager, Limpopo). The team met with the Gaza LSDI coordinator before visiting the main store room, and SP10 records for the past two spraying seasons were requested. Insecticide quantities were then assessed in the main insecticide store in Xai-Xai. All records of insecticides received, distributed and used were checked.
The main focus of the team was:
- To conduct an audit on insecticides in the province;
- To focus on insecticide records at provincial and district levels;
- To check the distribution and recording of insecticides;
- To check whether the quantity of insecticides in the main store room corresponds with the quantity issued to district store rooms.
Definitive Malaria diagnosis
Although microscopic blood smear analysis is the standard for diagnosing malaria, they have slow turn-around time, and were mostly used only for patients presenting with febrile illness. To improve diagnosis the use of rapid diagnostic tests (RDTs) was rolled out in Gaza Province. The initial roll out of RDTs was conducted by the LSDI, however, the future distribution of RDTs in Gaza Province have been taken over by the DPS.
Expansion of the LSDI Malaria Information System.
The Malaria Health Information System (MHIS) is a computerised management system that incorporates a spatial component using graphical information system (GIS) technology. The MHIS allows the input, management and output of malaria case data which is used for both management and research purposes. The types of malaria-related data that are managed by the system include (i) malaria case data and (ii) data on indoor residual spraying (IRS).
The system has been adapted to reduce end-user skill requirements and to optimise data access. The input screens mirror the data collection forms and the automatic-linking and drop-down lists help minimize data entry errors. The MHIS facilitates the identification and mitigation of problems in an ongoing fashion. To ensure the effective functioning of the MHIS requires technical expertise in the form of information officers (IOs) with the skills to operate and develop the MHIS.
The MHIS have proven to be a highly effective tool for evidence-based decision making, and have been established in Gaza province. Information collated by the MHIS plays a key role in the planning and monitoring of spray activities. The MHIS is a dynamic system that is continuously being updated and improved to ensure that comprehensive current data is provided.
Capacity Development
Skilled personnel and properly trained staff form the backbone of any effective vector control programme. There is a significant shortage of skills and experience in Gaza Province which presents a continuous need for the training of field staff (supervisors and spray operators).
Basic training of field staff focussed mainly on practical aspects of spraying (85%) accompanied by some theoretical background (15%). The more advanced training of supervisors, include in-depth training on environmental hazards, toxicity, first aid and the safe handling and disposal of insecticides. Field staff is also trained in the use of global positioning devices (GPS). Training takes place annually just before the start of the spraying season.
Entomologists are trained in necessary research techniques for field research as well as intervention assessment methodology. Included in this training is morphological identification of mosquitoes as well as the performance of bio-assays for susceptibility and biochemical resistance testing. Office staff is trained in the use of the health information system.
Impact assessment
Parasite prevalence
Baseline parasite prevalence surveys were conducted in zones four, five and six in September 2006 and in zone 7 in September 2008 for children in the 2 to <15 age group. Post-intervention surveys have been conducted in September 2007 and 2008 for zone four five and six, and will likewise be conducted for zone 7 in future years.
The prevalence of Plasmodium falciparum parasites Prevalence rates in children (2 to <5) in Gaza Province
The results of the average parasite prevalence in each zone are summarised in Figure 3. There is a clear reduction in prevalence in zones four, five and six between 2006 and 2007 and again between 2007 and 2008. In Zone four, prevalence was reduced by 37% after the first intervention and by a further 38% after the second intervention. In Zone five, prevalence were reduced by 26% after the first intervention followed by a further 40% reduction after the second intervention. In Zone six, prevalence was reduced by only 10% after the first intervention, but reduced by a further 54% after the second intervention. Interestingly enough, the initial prevalence in Zone seven (17%), is very similar to prevalence in zones 4 (15), 5 (24) and six (16) after two interventions. Figure 4 represents the change in percentage parasite prevalence within the different zones of Gaza province.
Illustration of the change in percentage prevalence of infection with Plasmodium falciparum parasites in children aged 2 to <15 in the Gaza province of Southern Mozambique
It is clear from Figure 4 that the parasite prevalence in children has decreased in all areas surveyed. Parasite prevalence was below 80% at all sentinel sites within Gaza, and with the exception of Conhane, Loc Da Praia and Muzingane, the prevalence at all sentinel sites was below 40%. This is a discernible indication that the control measures put into place in the Gaza province is positively impacting on the prevalence of Plasmodium falciparum within the communities residing in the province.
Drug resistance
Assessing the prevalence of molecular markers associated with sulphadoxine-Pyrimethamine (SP) resistance in the Plasmodium falciparum parasite is an integral component of case management in Gaza. Although SP is the second line treatment in Gaza, the drug is routinely used to treat uncomplicated malaria, and is also used for intermittent preventative treatment of children and pregnant woman in the province. Plasmodial DNA isolated from RDT positive samples during annual parasite prevalence surveys conducted at sentinel sites in Gaza province were analysed for the presence of these mutations.
The presence of mutations on the dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes, commonly referred to as “quintuple” mutation, are strongly associated with SP clinical failure.
Prevalence of dhfr triple mutation was almost at fixation in Zones 4, 5, and 6 prior to the implementation of malaria control in 2006 and it has remained unchanged. The baseline prevalence of dhfr triple mutation in Zone 7 is well over 85%.
Since the dhfr triple mutation has almost saturated the population, prevalence of the quintuple mutation, associated with SP treatment failure in southern Africa, is similar to that of the dhps double mutation. Preliminary results indicate that over 60% of the parasites in the region possess all five mutations linked with both in vitro and in vivo SP resistance. The high prevalence of the quintuple mutation is a cause for concern, particularly over the usefulness of SP for the treatment of malaria as an antimalarial and/or IPTp.. More research on the association between the effectiveness of IPTp using SP and the prevalence of highly resistance SP parasites is urgently needed.
The Results of mutational analysis conducted in Gaza province between 2006 and 2008 is summarised below:
Private Sector Partnership
Private sector involvement in the implementation of malaria control activities at community level is of paramount importance to the success and sustainability of the programme. Private sector involvement can also provide good leverage when applying for funding from donor organisations and bilateral partners.
Corridor Sands, a mining company, which is a subsidiary of BHP Billiton, have been involved with the programme in Gaza province. The company requested the implementation of malaria control activities similar to those implemented in the Mozal area of Maputo. This partnership has contributed to the earlier than planned implementation of malaria control in Zone 6. Apart from financial inputs, the company have also contributed to the logistics of the project by making storage space available for the storage of insecticides used in Gaza province. The Corridor Sands private partnership has also contributed to capacity development within the Gaza project.