A novel video-tracking system to quantify the behaviour of nocturnal mosquitoes attacking human hosts in the field.

Many vectors of malaria and other infections spend most of their adult life within human homes, the environment where they bloodfeed and rest, and where control has been most successful. Yet, knowledge of peri-domestic mosquito behaviour is limited, particularly how mosquitoes find and attack human hosts or how insecticides impact on behaviour. This is partly because technology for tracking mosquitoes in their natural habitats, traditional dwellings in disease-endemic countries, has never been available. We describe a sensing device that enables observation and recording of nocturnal mosquitoes attacking humans with or without a bed net, in the laboratory and in rural Africa. The device addresses requirements for sub-millimetre resolution over a 2.0 × 1.2 × 2.0 m volume while using minimum irradiance. Data processing strategies to extract individual mosquito trajectories and algorithms to describe behaviour during host/net interactions are introduced. Results from UK laboratory and Tanzanian field tests showed that Culex quinquefasciatus activity was higher and focused on the bed net roof when a human host was present, in colonized and wild populations. Both C. quinquefasciatus and Anopheles gambiae exhibited similar behavioural modes, with average flight velocities varying by less than 10%. The system offers considerable potential for investigations in vector biology and many other fields.

Patterns of malaria related mortality based on verbal autopsy in Muleba District, north-western Tanzania.

Reliable malaria related mortality data is important for planning appropriate interventions. However, there is scarce information on the pattern of malaria related mortality in epidemic prone districts of Tanzania. This study was carried out to determine malaria related mortality and establish its trend change over time in both epidemic and non-epidemic areas of Muleba District of north-western Tanzania. A verbal autopsy survey was conducted to obtain data on all deaths of individuals who died in six randomly selected villages from 1997 to 2006. Relatives of the deceased were interviewed using a standardized questionnaire. Communicable diseases accounted for about two thirds (61.9%) of deaths among > or =5 years individuals and 84.8% in < or =5 years. Non-communicable diseases accounted for 28.9% and 14.1% deaths in > or =5 years and < or =5 years, respectively. Malaria was the leading cause of deaths in all age groups (40.3%) and among children <5 years (73.8%). Infants accounted for about two third (64.5%) of all malaria related deaths in children <5 years. Peak of malaria proportional mortality was highest during malaria epidemics. Most of the malaria-related deaths in this group were among 1-12 months (64.5%) followed by 13-24 months (20.9%), and 25-59 months (14.8%). Cerebral malaria accounted for 18.9% (N=32) of death related to malaria in all age groups; 12.1% (17/141) were in under-five, 42.9% (6/14) were in 5-14 years and 64.3% (9/14) in 15-70 years old. More than half of malaria related deaths (61.0%) in <5 years children were associated with severe anaemia followed by diarrhoeal disease (24.1%), cerebral malaria (12.5%) and respiratory infection (8.5%) as common conditions. The majority of the deceased caretakers first sought treatment at health facilities within 24hr of the onset of illness. Significantly a higher proportion of caretakers of the underfives in the epidemic area sought treatment within 24hr than in non-epidemic area (39.3% vs. 18.5%; P = 0.0385). In conclusion, malaria accounts for majority of deaths in Muleba district, with substantial proportion being attributed to malaria epidemics.

Assessment of quality assurance in HIV testing in health facilities in Lake Victoria zone, Tanzania.

Tanzania is currently implementing the antiretroviral treatment programme, and has a target of putting about 400,000 eligible HIV infected individuals on treatment by 2008. This will involve screening a large number of people, which will require non-laboratory personnel to be involved in doing HIV testing. In order to guarantee reliable and quality HIV test results, there is a need to ensure that quality assurance (QA) procedures are followed from specimen collection, testing and reporting of results. In light of the above a survey was conducted to assess QA in HIV testing in health facilities in Lake Victoria zone, Tanzania. A total of 89 health facilities (29 hospitals, 34 health centres, 9 dispensaries and 17 voluntary and counselling testing centres) were surveyed. Only three (10.3%) health facilities reported performing Uniform II ELISA for HIV diagnosis. All other health facilities reported to be using HIV rapid tests Capillus and Determine. Five (5.6%) of health facility laboratories performed CD4 counts. Internal quality control (IQC) were performed in 21 (63.6%) of the hospitals. Kits for HIV testing were reported to be readily available by 54 (60.7%) of the facilities. Only 16 (18%) of the health facilities had standard operating procedures in place. Systems of equipment calibration were reported by 13 (14.6%) of the health facilities. Counselling services were available in all health facilities and all counsellors had received the 6-week mandatory training course. These findings show that most of health facilities in the Lake Victoria zone do not adhere to QA procedures in HIV testing. There is therefore, a need to establish a monitoring system to laboratories performing HIV testing for the purpose of ensuring QA procedures are done. Personnel doing HIV testing should be re-trained at a regular basis to cope with new techniques and ensure QA procedures are followed.