Sampling techniques for adult Afrotropical malaria vectors and their reliability in the estimation of entomological inoculation rate

Various entomological indicators and sampling techniques are used to monitor and evaluate the impact of many vector control interventions. A number of methods have been used in sampling mosquitoes for the purpose of estimating the entomological inoculation rate (EIR) and each is subject to some bias or shortcomings. It was the aim of this paper to critically evaluate the most common mosquito sampling techniques in relation to their reliability in the estimation of EIR. The techniques include man-landing, light trap, light trap/bednet combination and odour-baited traps. Although man-landing technique is the most reliable, it however, expose the catcher to mosquito-borne infections. On the other hand, light traps have been found to capture mosquitoes with higher sporozoite rates as compared to those from human bait catch thus leading to an overestimation of EIR. From an epidemiological point of view, the use of light-trapbed net combination is an approach that is more meaningful than using light trap alone because, a light trap functions more efficiently when placed near the normal flight paths of mosquitoes such as inside huts or under the eaves. Unfortunately, it has been shown that estimates of EIR are influenced by trap position, hence affecting the number caught and the sporozoite rates. A variety of bednets have been used to sample mosquitoes attracted to man. Studies have shown that bednet traps normally catch fewer mosquitoes than do human baits outside them. Although the collections by indoor resting technique give a good estimate of the mean house density in a given area, they may not necessarily give a good estimate of EIR. Thus the development of improved sampling systems based on an improved understanding of hostoriented behaviour is needed. Moreover, there is need to standardise all the sampling techniques in use to enable us make valid comparisons between various studies done by different people and in different areas. In this article, the inherent limitations of conventional mosquito sampling techniques when used in estimating the EIR are discussed. Keywords: malaria vector, sampling, traps, entomological inoculation rate, Africa Tanzania Health Research Bulletin Vol. 7(3) 2005: 117-12

Editorial: Fifty years of health services in Tanzania: What next?

Before independence in 1961, Tanzania was a Germany colony (1889-1916) and later British Protectorate (1916-1961). During the 72 year period, the western medical services targeted foreigners working for the colonial governments. After independence, the government has expanded the health services with a vision to improve the health and well being of all Tanzanians with a focus on those most at risk, and to encourage the health system to be more responsive to the needs of the people. The policy mission is to facilitate the provision of equitable, quality and affordable basic health services, which are gender sensitive and sustainable, delivered for the achievement of improved health status. This issue of the Tanzania Journal of Health Research is dedicated for the 50th Anniversary of the Tanzania independence. It includes a number of reviews focussed on different aspects of health, both communicable and non-communicable diseases. The reviews focus on a number of health problems that faced Tanzania during the past fifty years. Challenges to meet the national and global development goals are discussed in line with the changing epidemiological patterns for both communicable and non-communicable diseases

Short Report: Influence of Centers for Disease Control Light Trap Position, Relative to a Human-Baited Bed Net, on Catches of Anopheles Gambiae and Culex Quinquefasciatus in Tanzania.

The best position for Centers for Disease Control (Atlanta, GA) light traps, in relation to human-occupied bed nets for trapping of host-seeking Anopheles gambiae Giles and Culex quinquefasciatus Say mosquitoes, was determined in Tanzania. Significantly higher catches were recorded for both species when the trap was positioned at the foot end of the bed, near the top of the net. Parity rates were significantly higher near the top of the net than at the level of the host. Since trap position affects the catch size and the proportion of infectious mosquitoes therein, standardized use of this sampling technique for estimating entomologic inoculation rates (i.e., the number of potentially infectious bites received over a certain period of time) is recommended

The role of mass media in disease outbreak reporting in the United Republic of Tanzania

Emerging infectious diseases and the growth of information communication technology have produced new demands and possibilities for disease outbreak information and reporting. An analysis of disease outbreak information and reporting by the Tanzanian mass media was carried out to cover a 12-month period between July 2002 and June 2003. Outbreak episodes reported in four local dailies were collected, compiled and analysed. The disease that received the highest coverage was cholera. Cholera outbreaks were frequently reported from the 3 districts in Dar es Salaam Region. Other epidemic-prone diseases received very little coverage. These included meningitis and rabies. With globalisation and high technological information systems, reports of disease outbreaks are more widely disseminated and more easily accessible than ever before. However, the quality of information is no longer controlled and may be provided out of context, often causing unnecessary public anxiety and confusion. It is important that mass media is provided with accurate epidemiological reports if correct information is to reach the public. The role of media in outbreak reporting is herein discussed in relation to the importance of providing timely and accurate epidemiological information. Tanzania Health Research Bulletin Vol.6(2) 2004: 73-7

Regional Initiatives in Support of Surveillance in East Africa: The East Africa Integrated Disease Surveillance Network (EAIDSNet) Experience.

The East African Integrated Disease Surveillance Network (EAIDSNet) was formed in response to a growing frequency of cross-border malaria outbreaks in the 1990s and a growing recognition that fragmented disease interventions, coupled with weak laboratory capacity, were making it difficult to respond in a timely manner to the outbreaks of malaria and other infectious diseases. The East Africa Community (EAC) partner states, with financial support from the Rockefeller Foundation, established EAIDSNet in 2000 to develop and strengthen the communication channels necessary for integrated cross-border disease surveillance and control efforts. The objective of this paper is to review the regional EAIDSNet initiative and highlight achievements and challenges in its implementation. Major accomplishments of EAIDSNet include influencing the establishment of a Department of Health within the EAC Secretariat to support a regional health agenda; successfully completing a regional field simulation exercise in pandemic influenza preparedness; and piloting a web-based portal for linking animal and human health disease surveillance. The strategic direction of EAIDSNet was shaped, in part, by lessons learned following a visit to the more established Mekong Basin Disease Surveillance (MBDS) regional network. Looking to the future, EAIDSNet is collaborating with the East, Central and Southern Africa Health Community (ECSA-HC), EAC partner states, and the World Health Organization to implement the World Bank-funded East Africa Public Health Laboratory Networking Project (EAPHLNP). The network has also begun lobbying East African countries for funding to support EAIDSNet activities

Indoors man-biting mosquitoes and their implication on malaria transmission in Mpwapwa and Iringa District, Tanzania

No Abstract

Chemical ecology of the behaviour of the filariasis mosquito Culex quinquefasciatus Say

Culex quinquefasciatus is an important vector of urban bancroftian filariasis in the tropical world. Despite its public health importance, much of its olfactory mediated behaviour is poorly understood. Studies on resource-location behaviour, in particular the role of semiochemicals in its behaviour, are required to understand the relationship between the mosquito, its host and the surrounding environment to effectively control bancroftian filariasis. In this thesis the role of semiochemicals in the host-location behaviour and oviposition site-selection of Cx quinquefasciatus has been examined.The olfactory responses of the host-seeking female Cx quinquefasciatus to various odour stimuli in a dual-choice olfactometer showed that the mosquito responds more to foot skin emanations than to carbon dioxide and moisture. These results present evidence that kairomones used during the host-seeking process by Cx quinquefasciatus are present in human skin emanations. The preference of Cx quinquefasciatus between humans, and domestic animals, was investigated in the field. The response of the mosquito to the humans, cattle and goats was also compared to its response to carbon dioxide. The mosquito responded to human olfactory cues in significantly larger numbers than to the calf or goat cues. The response of the mosquito to either the calf or goat was similar.It can be concluded that with equal availability of the three vertebrates, Cx quinquefasciatus would respond significantly more to cues from human hosts than from either a calf or a goat. The major olfactory cue from goat or a calf, to which this mosquito responds is probably carbon dioxide. Furthermore, the response of Cx quinquefasciatus, Anopheles gambiae s.l. and An. funestus to human odour was compared with that to carbon dioxide in the field. Human odour attracted a larger number of host-seeking Cx quinquefasciatus, An. gambiae and An. funestus than carbon dioxide.In an indoor situation human body odour other than carbon dioxide is the principal cue to which these mosquito species respond and that the physical cues from a host and carbon dioxide, when used as a kairomone on its own, account for a minor part of the overall attractiveness of man. Skin emanations and various specific organochemical compounds known to attract other blood sucking Diptera were tested for Cx quinquefasciatus in the field. It was found for the first time that Cx quinquefasciatus can be trapped into traps baited with human skin residues. Furthermore a larger number of Cx quinquefasciatus were caught in traps baited with carbon dioxide than in traps baited with either acetone, octenol or butyric acid. The combination of carbon dioxide and skin emanations resulted in an additive effect. These results indicate that under field conditions Cx quinquefasciatus can be sampled by traps baited with skin emanations and/or carbon dioxide.As far as the odour-mediated oviposition behaviour is concerned it was found that the oviposition by Cx quinquefasciatus occurs more frequently in the presence of the mosquito oviposition pheromone and/or skatole than in plain water. The daily oviposition rhythm of Cx quinquefasciatus showed two peaks, the higher at twilight and the lower peak at dawn. The biological activities of the synthetic oviposition pheromone (acetoxyhexadecanolide) and skatole were found to last for over 9 and 7 days respectively.It was further found that the combination of synthetic oviposition pheromone and soakage pit water or grass infusions resulted in a synergistic response in the oviposition by Cx quinquefasciatus, Cx cinereus and Cx tigripes. However, a blend of synthetic oviposition pheromone and skatole resulted into an additive oviposition response by Cx quinquefasciatus . Oviposition semiochemicals can thus be used as ovitraps or gravid mosquito traps to monitor Cx quinquefasciatus populations or to attract mosquitoes to sites treated with a biopesticide for vector control.The efficiency of various odour baited sampling devices was also investigated. It was found that the efficiency of the widely used Centers for Disease Control (CDC) light trap in sampling an indoor population of Cx quinquefasciatus and An. gambiae is affected by the position of the trap in relation to the human-baited bed net. Significantly higher catches were recorded for both species when the trap was positioned at the foot-end of the bed, near the top of the bed net. Parity rates were significantly higher near the top of the net than at the level of the host. In addition, infective Cx quinquefasciatus were caught in the trap positioned above the foot-end of the bed net.Various trapping systems baited with carbon dioxide were compared in sampling outdoor populations of An. gambiae and Cx quinquefasciatus . The efficiency of the Counterflow Geometry (CFG) trap was similar to that of electric nets (ENT). Both CDC traps with light or without light were less efficient in collecting An. gambiae or Cx quinquefasciatus outdoors. It is possible, therefore, to collect the two mosquito species outdoors with CFG traps or ENT baited with carbon dioxide. Finally an assessment of traps baited with oviposition semiochemicals in sampling of gravid Cx quinquefasciatus is reported. A CFG trap baited with either a synthetic oviposition pheromone, grass infusions or the combination of the two was found to be a useful tool for collecting gravid Cx quinquefasciatus both indoors and outdoors. However, the proportion of gravid mosquitoes in the catches increased when the traps were placed away from mosquito emergence sites. In conclusion, the study shows that chemical ecology plays a significant role in the life cycle of Cx quinquefasciatus and this principle can be used to develop new control strategies.</p

Food insecurity and coping strategies among people living with HIV in Dar es Salaam, Tanzania

Food insecurity and malnutrition seriously impedes efforts to control HIV/AIDS in resource poor countries. This study was carried out to assess food security, and coping strategies among people living with HIV/AIDS (PLHIV) attending Care and Treatment Centre (CTC) in Dar es Salaam, Tanzania. A structured questionnaire was used to interview randomly selected adults (≥18 years) who were HIV positive who have just been eligible for anti-retroviral treatment (ART) in a CTC or one who has started ART but not more than four weeks has elapsed. A total of 446 (females=67.9%; males= 32.1%) people living with HIV/AIDS attending CTC were interviewed. About three quarters (73.1%) of the respondents were 25-44 years old and most (43.9%) were married. Two thirds (66.7%) of the respondents had primary school education. Seventy percent reported to have a regular income and 63.7% with a monthly income of less than US$154. More than half (52.2$154) (OR=0.10; 95%CI, 0.01–0.67). Reporting two or less meals increased the likelihood of food insecurity (OR=4.2; 95% CI1.7-9.8). Low frequency of meals was significantly more prevalent (18.6%) among those ≥45 years than among 35–44 years old respondents (6.7%) (P=0.04). Borrowing money (55.8%) and taking less preferred foods (53.3%) were the most common coping strategies. In conclusion, food insecurity is a significant problem among people living with HIV in Dar es Salaam which might significantly affect compliance to care and support. The study suggests that counselling of PLHIV before anti-retroviral treatment programmes should devise special strategies targeting those with low education, low income and low frequency of meals

Maternal health in fifty years of Tanzania independence: Challenges and opportunities of reducing maternal mortality

High rate of maternal death is one of the major public health concerns in Tanzania. &nbsp;Most of maternal deaths are caused by factors attributed to pregnancy, childbirth and poor quality of health services. More than 80% of maternal deaths can be prevented if pregnant women access essential maternity care and assured of skilled attendance at childbirth as well as emergency obstetric care. The objective of this review was to analyse maternal mortality situation in Tanzania during the past 50 years and to identify efforts, challenges and opportunities of reducing it. This paper was written through desk review of key policy documents, technical reports, publications and available internet-based literature. From 1961 to 1990 maternal mortality ratio in Tanzania had been on a downward trend from 453 to 200 per 100,000 live births. However, from 1990&rsquo;s there been an increasing trend to 578 per 100,000 live births. Current statistics indicate that maternal mortality ratio has dropped slightly in 2010 to 454 per 100,000 live births. Despite a high coverage (96%) in pregnant women who attend at least one antenatal clinic, only half of the women (51%) have access to skilled delivery. Coverage of emergence obstetric services is 64.5% and utilization of modern family planning method is 27%. Only about 13% of home deliveries access post natal check-up. Despite a number of efforts maternal mortality is still unacceptably high. Some of the efforts done&nbsp; to reduce maternal mortality in Tanzania included the following initiatives: reproductive and child survival; increased skilled delivery; maternal death audit; coordination and integration of&nbsp; different programs including maternal and child health services, family planning, malaria interventions, expanded program on immunization &nbsp;and adolescent health and nutrition programmes. These initiatives are however challenged by inadequate access to maternal health care services. In order to considerably reduce maternal deaths some of recommended strategies include: (i) strengthening the health system to provide skilled attendance during child birth; (ii) upgrading rural health centres to provide emergency obstetric services; (iii) providing adolescent and male friendly family planning services; (iv) strengthening public&ndash;private partnership to ensure continuum of care; (v) supporting operational research to answer the immediate concerns of the health system; and (vi) strengthening community participation and women empowerment to take role of their own health and the family at large. In conclusion, maternal mortality ratio in Tanzania is unacceptably high and still very far from reaching the millennium development goals. Maternal health care services should focus on ensuring there is continuum of care through strengthening the health system; provision of good quality of health care in a well organized referral health system and operation research to support programme implementation

Challenges and opportunities in building health research capacity in Tanzania: a case of the National Institute for Medical Research

Capacity building is considered a priority for health research institutions in developing countries to achieve the Millennium Development Goals by 2015. However, in many countries including Tanzania, much emphasis has been directed towards human resources for health with the total exclusion of human resources for health research.&nbsp; The objective of this study was to systematically investigate the capacity building process for the Tanzanian National Institute for Medical Research (NIMR) over a 30-year period and identify the challenges and opportunities in creating a critical mass of multi-disciplinary research scientists that is required for achieving the intended health benefits. A desk review of personnel database was conducted for information covering 1980-2009 on academic qualifications, training, research experience and research output. The current staff curriculum vitae (CV) were reviewed to gather information on researchers&rsquo; employment record, training, training support, area of expertise and scientific output. Interviews were conducted with a cross section of researchers on capacity development aspects using a self-administered questionnaire. In-depth interviews were also conducted with the current and former NIMR Management to seek information on capacity development challenges. A review was also done on staff personal files, annual reports, strategic plans and other occasional documents. A total of 163 CV were assessed; of these, 76.7% (125) were for Research Scientists (RS), 20.9% (34) Laboratory Technologists (LT) and 2.4% (4) for System Analysts. The Institute had 13 research scientists upon its establishment. Since 1980, NIMR has recruited a total of 185 Research Scientists. By 2009, NIMR had a total scientific workforce of 170 staff (RS= 82.4%; LT= 17.6%). Of the 140 RSs, 37 (26.4%) were first degree; 77 (55.5%) second degree while 26 (18.6%) were PhD degree holders. Of the total of 78 researchers interviewed, 55 (70.5%) indicated to have accessed postgraduate training through their personal efforts and 23 through institutional arrangement. Sixty (77%) respondents were satisfied with their tenure at NIMR. Seventy (89%) indicated that they had not at any point considered leaving NIMR. Most (79%) research scientists were recruited while holding a first degree, a few (17%) with second degree while only one (0.7%) holding a PhD degree. NIMR has experienced a research scientist attrition rate of 17.5%. Staff retention factors included availability of training opportunities; passion for conducting research; and good career prospects. Despite having a training programme, the institute has never at any moment been able to hold its own training resources. Being a public research institution, NIMR receives its core funding from the government of the United Republic of Tanzania. The bulk of the funding appears to be spent on personnel emoluments that take up to 85% (mean= 66%) of the allocated budget. In conclusion, the current NIMR&rsquo;s research capacity building is dependent mainly on foreign funding and personal initiatives. There is an urgent need to increase local funding for capacity building and conduct of research. A programme should be put in place to ensure sustainability of the capacity building process