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Biomedical subjects

D N Durrheim

Publications and source records attributed to D N Durrheim.

At least 19 recordsLinked to original sources

The argument for integrating vector control with multiple drug administration campaigns to ensure elimination of lymphatic filariasis.

BACKGROUND: There is a danger that mass drug administration campaigns may fail to maintain adequate treatment coverage to achieve lymphatic filariasis elimination. Hence, additional measures to suppress transmission might be needed to ensure the success of the Global Program for the Elimination of Lymphatic Filariasis. DISCUSSION: Vector control successfully eliminated lymphatic filariasis when implemented alone or with mass drug administration. Challenges to lymphatic filariasis elimination include uncertainty of the exact level and duration of microfilarial suppression required for elimination, the mobility of infected individuals, consistent non-participation of some infected individuals with mass drug administration, the possible development of anti-filarial drug resistance and treatment strategies in areas co-endemic with loasis. Integration of vector control with mass drug administration can address some of these challenges. The potential benefits of vector control would include: (1) the ability to suppress filariasis transmission without the need to identify all individual 'foci of infection'; (2) minimizing the risk of reestablishment of transmission from imported microfilaria positive individuals; and (3) decreasing the risk of dengue or malaria transmission where, respectively, Aedes or Anopheles are lymphatic filariasis vectors. SUMMARY: With adequate sustained treatment coverage, mass drug administration should meet the criteria for elimination of lymphatic filariasis. However, it may be difficult to sustain sufficiently high mass drug administration coverage to achieve lymphatic filariasis elimination in some areas, particularly, where Aedes species are the vectors. Since vector control was effective in controlling and even eliminating lymphatic filariasis transmission, integration of vector control with mass drug administration will ensure the sustainability of transmission suppression and thereby better ensure the success of national filariasis elimination programs. Although trials of some vector control interventions are needed, proven vector control strategies are ready for immediate integration with mass drug administration for many important vectors. Vector control is the only presently available additional lymphatic filariasis control measure with the potential for immediate implementation.

Journal Article↗

Strongyloides serology--useful for diagnosis and management of strongyloidiasis in rural Indigenous populations, but important gaps in knowledge remain.

General practitioners who care for Aboriginal patients in rural and remote communities from tropical Australia must be aware of strongyloidiasis. The prevalence of this parasitic infection is high and occasional cases can have a fatal outcome. Other groups in Australia at high risk of strongyloidiasis are immigrants from endemic countries, particularly from Southeast Asia, and military personnel who have served overseas in endemic areas. Elimination programs for enteric parasites in rural Australian Indigenous communities are so important that a nationally coordinated approach has been advocated. Wisely used, cost-effective diagnostic tests are a critical component of an elimination program. Strongyloidiasis must be confirmed by laboratory diagnosis and the strongyloides ELISA, although not ideal, is a useful test that can be used to diagnose strongyloidiasis and to monitor cure. In this article the value of the current strongyloides ELISA is discussed and a cost-benefit analysis is conducted using direct costs only. In a typical rural Aboriginal community in tropical Australia with prevalence of strongyloidiasis at 20% each true positive case detected by the strongyloides ELISA is estimated to cost approximately AU590 dollars to diagnose and manage until cure, proven by negative serology.

Journal Article↗

Using a geographical information system to plan a malaria control programme in South Africa.

INTRODUCTION: Sustainable control of malaria in sub-Saharan Africa is jeopardized by dwindling public health resources resulting from competing health priorities that include an overwhelming acquired immunodeficiency syndrome (AIDS) epidemic. In Mpumalanga province, South Africa, rational planning has historically been hampered by a case surveillance system for malaria that only provided estimates of risk at the magisterial district level (a subdivision of a province). METHODS: To better map control programme activities to their geographical location, the malaria notification system was overhauled and a geographical information system implemented. The introduction of a simplified notification form used only for malaria and a carefully monitored notification system provided the good quality data necessary to support an effective geographical information system. RESULTS: The geographical information system displays data on malaria cases at a village or town level and has proved valuable in stratifying malaria risk within those magisterial districts at highest risk, Barberton and Nkomazi. The conspicuous west-to-east gradient, in which the risk rises sharply towards the Mozambican border (relative risk = 4.12, 95% confidence interval = 3.88-4.46 when the malaria risk within 5 km of the border was compared with the remaining areas in these two districts), allowed development of a targeted approach to control. DISCUSSION: The geographical information system for malaria was enormously valuable in enabling malaria risk at town and village level to be shown. Matching malaria control measures to specific strata of endemic malaria has provided the opportunity for more efficient malaria control in Mpumalanga province.

Databases, Factual↗

The use of hospital-based nurses for the surveillance of potential disease outbreaks.

OBJECTIVE: To study a novel surveillance system introduced in Mpumalanga Province, a rural area in the north-east of South Africa, in an attempt to address deficiencies in the system of notification for infectious conditions that have the potential for causing outbreaks. METHODS: Hospital-based infection control nurses in all of Mpumalanga's 32 public and private hospitals were trained to recognize, report, and respond to nine clinical syndromes that require immediate action. Sustainability of the system was assured through a schedule of regular training and networking, and by providing feedback to the nurses. The system was evaluated by formal review of hospital records, evidence of the effective containment of a cholera outbreak, and assessment of the speed and appropriateness of responses to other syndromes. FINDINGS: Rapid detection, reporting and response to six imported cholera cases resulted in effective containment, with only 19 proven secondary cholera cases, during the two-year review period. No secondary cases followed detection and prompt response to 14 patients with meningococcal disease. By the end of the first year of implementation, all facilities were providing weekly zero-reports on the nine syndromes before the designated time. Formal hospital record review for cases of acute flaccid paralysis endorsed the value of the system. CONCLUSION: The primary goal of an outbreak surveillance system is to ensure timely recognition of syndromes requiring an immediate response. Infection control nurses in Mpumalanga hospitals have excelled in timely weekly zero-reporting, participation at monthly training and feedback sessions, detection of priority clinical syndromes, and prompt appropriate response. This review provides support for the role of hospital-based nurses as valuable sentinel surveillance agents providing timely data for action.

Cholera↗

Malaria outbreak control in an African village by community application of 'deet' mosquito repellent to ankles and feet.

The malaria vector Anopheles arabiensis Patton (Diptera: Culicidae) shows a marked predilection (> 80%) for biting the ankles and feet of human subjects, as revealed by our previous observations at Malahlapanga in the Kruger National Park, South Africa. Topical application of insect repellent, 15% deet (N,N-diethyl-3-methylbenzamide), to feet and ankles reduced the overall biting rate of An. arabiensis by 69%. A focal malaria epidemic in Albertsnek village (25 degrees 33'S, 31 degrees 59' E) near the Mozambique border, following flooding during February 2000, provided an opportunity to apply these findings of operational research for outbreak containment. Twice-nightly topical application of deet to ankles and feet of Albertsnek inhabitants was followed by rapid restoration of preepidemic malaria incidence levels after one incubation period. This encouraging outcome should be attempted in other outbreak-prone settings where infective mosquito bites are sporadic and malaria has unstable endemicity.

Animals↗

Rabies post-exposure management in South Africa: a telephonic survey used as a rapid tool for operational research.

Rabies is an important disease in rural South Africa, and vaccine and immunoglobulin are provided, at the State's expense, to humans following suspected exposure to rabies virus by bite, scratch or mucosal splash. Health facilities where post-exposure treatment is available are listed, with contact telephone numbers, in national rabies guidelines. To verify the accuracy of this recently updated information, members of the national Rabies Advisory Group were tasked to complete a rapid survey. A simple standardized telephone interview technique was used. This revealed startling deficiencies in the availability of vaccine and immunoglobulin at the indicated sites and led to decisive corrective action. This 'quick and dirty' survey technique provided valuable information for improving an important public health programme, and should be considered when auditing other health programmes, particularly where a means for validating responses is readily available.

Animals↗

Leprosy in Mpumalanga Province, South Africa--eliminated or hidden?

In South Africa, leprosy has been a notifiable condition since 1921. Although the WHO elimination target of less than one case per 10,000 population has been achieved at country level, the distribution of leprosy in the country is distinctly heterogeneous, with a prominent 'leprosy belt' of greater prevalence stretching across Mpumalanga Province into northern Kwa-Zulu Natal. The highest prevalence in this 'belt' has historically been in Ermelo District. Recent trends of few newly detected leprosy patients in this district raised concerns that health system changes may have resulted in failure to detect leprosy cases. Thus a large-scale community awareness campaign was conducted followed by an intensively advertised screening programme of 3-month duration at schools and central gathering points in villages and farms from 1 June to 31 August 2000. One thousand one hundred and seventy-seven people presented for clinical screening at designated points, while 790 scholars were screened at schools and an additional 1433 people were screened at their homes by the field team. Forty-four people with skin or nervous system lesions compatible with leprosy were referred for specialized assessment and biopsy where indicated. Four new leprosy patients were diagnosed, including an elderly lady with pronounced disability. Two of these patients had prior contact with the health service due to dermatological manifestations of leprosy without diagnosis being made. All patients provided a history of close prolonged contact with known leprosy patients. Ongoing intense tracing and follow-up of close contacts of proven leprosy cases may be a more efficient method of detecting leprosy cases in areas with relatively stable populations that have accomplished 'leprosy elimination', than resource intensive community surveys.

Adult↗

Repellent effects on Anopheles arabiensis biting humans in Kruger Park, South Africa.

Distribution of biting sites on the human body by the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae) was investigated near a source of mosquitoes in the Kruger National Park, South Africa. Eight adult male volunteers (2 teams x 2 pairs of subjects) conducted human bait collections while seated on camp chairs in the open-air, wearing only short trousers (no shirt, socks or shoes). Mosquito collections during 18.30-22.30 hours on five consecutive nights in April 1998 yielded a total of 679 An. arabiensis females biting subjects with or without their ankles and feet treated with deet insect repellent (15% diethyl-3-methylbenzamide, Tabard lotion). On subjects whose feet and ankles were smeared with repellent, 160 An. arabiensis females were captured biting in 60 manhours: 88.1% on the legs, 1.4% on the arms and 1.2% on other parts of the body, but none on the repellent-treated feet or ankles. On subjects without repellent treatment, 519 An. arabiensis were caught biting in 60 man-hours: 81.1% on feet and ankles, 16.4% on legs, 1.4% on arms and 1.2% on the rest of the body. For individual subjects, the reduction of An. arabiensis bites ranged from 36.4 to 78.2% (mean protection 69.2%). Results of this study confirm previous findings that, in this part of South Africa - inhabited only by wildlife - when people sit outside during the evening An. arabiensis prefers to bite their lower limbs: 97.5% below the knees. Overall, the number of bites by the malaria vector An. arabiensis was reduced more than three-fold (from 26 to 8/person/evening), simply by treating ankles and feet with a consumer brand of deet repellent. Whether or not this provides a satisfactory degree of protection against malaria risk would depend on the malaria sporozoite rate in the malaria vector population.

Adult↗

Rapid immunochromatographic diagnosis and Rolling Back Malaria--experiences from an African control program.

Malaria is a re-emerging disease in much of Africa. In response, the World Health Organization launched the Roll Back Malaria (RBM) initiative. One of six key principles adopted is the early detection of malaria cases. However, the importance of definitive diagnosis and potential value of field deployment of rapid malaria tests in RBM has been largely ignored. The Lowveld Region of Mpumalanga Province, South Africa, is home to a predominantly non-immune population, of approximately 850000 inhabitants, who are at risk of seasonal Plasmodium falciparum malaria. Malaria treatment in this area is usually only initiated on detection of malaria parasites in the peripheral bloodstream, as many other rickettsial and viral febrile illness mimic malaria. The malaria control programme traditionally relied on light microscopy of Giemsa-stained thick blood films for malaria diagnosis. This review summarizes operational research findings that led to the introduction of rapid malaria card tests for primary diagnosis of malaria throughout the Mpumalanga malaria area. Subsequent operational research and extensive experience over a four-year period since introducing the ICT Malaria Pf test appears to confirm the local appropriateness of this diagnostic modality. A laboratory is not required and clinic staff are empowered to make a prompt definitive diagnosis, limiting delays in initiating correct therapy. The simple, accurate and rapid non-microscopic means now available for diagnosing malaria could play an important role in Rolling Back Malaria in selected areas.

Communicable Disease Control↗

Efficacy of three insect repellents against the malaria vector Anopheles arabiensis.

Three commercial repellents marketed in South Africa: Bio-Skincare (BSC, oils of coconut, jojoba, rapeseed and vitamin E), Mosiguard towelletes with 0.574 g quwenling (p-menthane-3,8-diol, PMD) and the standard deet (15% diethyl-3-methylbenzamide, Tabard lotion), were compared against a laboratory colony of the mosquito Anopheles arabiensis Patton (Diptera: Culicidae), the predominant malaria vector in South Africa. Human forearms were treated with 1.2 g BSC, 0.8 g PMD towelette or 0.5 g deet and exposed to 200 hungry An. arabiensis females for 1 min, at intervals of 1-6 h post-treatment. Tests were conducted by three adult male volunteers (aged 30-45 years, crossover controlled test design for 3 consecutive days), using their left arm for treatment and right arm for untreated control. Biting rates averaged 39-52 bites/min on untreated arms. All three repellents provided complete protection against An. arabiensis for up to 3-4 h post-application; deet and PMD gave 90-100% protection up to 5-6h, but BSC declined to only 52% protection 6h post-treatment. These results are interpreted to show that all three repellent products give satisfactory levels of personal protection against An. arabiensis for 4-5 h, justifying further evaluation in the field.

Adult↗