The impact of changing the diagnostic algorithm for TB in Manicaland, Zimbabwe.

SETTING: Governmental health facilities performing TB diagnostics in Manicaland, Zimbabwe. OBJECTIVE: To investigate the effect of making Xpert® MTB/RIF the primary TB diagnostic for all patients presenting with presumptive TB on 1) the number of samples investigated for TB, 2) the proportion testing TB-positive, and 3) the proportion of unsuccessful results over time. DESIGN: This retrospective study used data from GeneX-pert downloads, laboratory registers and quality assurance reports between 1 January 2017 and 31 December 2018. RESULTS: The total number of Xpert tests performed in Manicaland increased from 3,967 in the first quarter of 2017 to 7,011 in the last quarter of 2018. Mycobacterium tuberculosis DNA was detected in 4.9-8.6% of the samples investigated using Xpert, with a higher yield in 2017 than in 2018. The overall proportion of unsuccessful Xpert assays due to "no results", errors and invalid results was 6.3%, and highly variable across sites. CONCLUSION: Roll out of more sensitive TB diagnostics does not necessarily result in an increase of microbiologically confirmed TB diagnosis. While the number of samples tested using Xpert increased, the proportion of TB-positive tests decreased. GeneXpert soft- and hardware infrastructure needs to be strengthened to reduce the rate of unsuccessful assays and therefore, costs and staff time.

LIEU: Centres de soins gouvernementaux réalisant des tests diagnostiques de la TB au Manicaland, Zimbabwe. OBJECTIF: Analyser l'effet de l'utilisation du test Xpert® MTB/RIF en tant que test diagnostique principal de la TB chez tous les patients suspects de TB sur 1) le nombre d'échantillons analysés pour TB, 2) la proportion d'échantillons testés positifs à la TB et 3) la proportion de résultats infructueux au fil du temps. MÉTHODE: Cette étude rétrospective a utilisé les données extraites du système GeneXpert, des registres de laboratoire et des rapports d'assurance qualité entre le 1er janvier 2017 et le 31 décembre 2018. RÉSULTATS: Le nombre total de tests Xpert réalisés au Manicaland a augmenté, de 3 967 au premier trimestre 2017 à 7 011 au dernier trimestre 2018. L'ADN de Mycobacterium tuberculosis a été détecté dans 4,9­8,6% des échantillons analysés par test Xpert, avec un rendement plus élevé en 2017 qu'en 2018. La proportion globale de tests Xpert infructueux en raison d'une « absence de résultat ¼, d'erreurs ou de résultats non valides était de 6,3%, avec une forte variation en fonction des sites. CONCLUSION: Le déploiement de tests diagnostiques de la TB plus sensibles n'entraîne pas nécessairement une hausse des diagnostics de TB confirmés microbiologiquement. Alors que le nombre d'échantillons testés par test Xpert a augmenté, la proportion de tests positifs pour la TB a diminué. L'infrastructure du matériel et du logiciel GeneXpert doit être renforcée pour réduire le taux de tests infructueux, et donc les coûts et le temps consacré par le personnel à la réalisation de ces tests.

Status of the Artemisinin Resistance-Associated PfATPase6 S769N Mutation in Plasmodium Falciparum Infections of Lusaka Urban District; Zambia

Objective: Artemisinin derivatives constitute a key component of the present-day treatment for Plasmodium falciparum malaria. In Zambia the national malaria policy was revised in 2003 to replace chloroquine mono-treatment with artemisinin combination therapy (ACT). Resistance to artemisinin is associated with a S769N point mutation in the sarcoendoplasmic reticulum calcium-dependant ATPase6 (SERCA-PfATPase6) gene of P. falciparum. However; the baseline or current levels of this mutation in Zambia remain unknown. The present study was aimed at determining the prevalence of the putative artemisinin resistance marker and the extent to which the recommended ACT (artemether-lumefantrine) was in use in Lusaka Urban district. Design: This was a cross sectional prospective study. Using a nested PCR and allele specific restriction enzyme digestion strategy; P. falciparum infections from ten sites in Lusaka urban district were assayed for the prevalence of the PfATPase6 S769N mutation. The availability of current ACT and the extent to which it has been used since introduction were assessed using interview by questionnaire. Main Outcome: The PfATPase6 S769N mutation was not found on any of the infections analyzed in the present study. Artemether-lumefantrine ACT was readily available in both government-owned health centres and private drug stores as first line malaria treatment in Lusaka urban district. Conclusion: The absence of the PfATPase6 S769N mutation suggests 100artemisinin sensitivity unless a different resistance mechanism exists. Continued resistance monitoring and investigation of other potential molecular markers is recommended as wider ACT use is scaled up in the country

A Synopsis of Current Malaria Diagnosis Trends

Malaria has remained a major cause of morbidity and mortality in the under developed and developing countries of the tropical and sub-tropical regions of the world. Globally 3.3 billion people live in areas where malaria exists; affecting 300-500 million people annually and it is estimated to be killing approximately 1-3 million people each year and 90of these mortalities occur in African children especially in sub Saharan Africa. Currently; although several control methods are beginning to result in downward trends in incidence in some countries; the gross number of malaria cases is still on the increase due to several factors including poor and ineffective diagnosis. Prompt and effective diagnosis is essential for the management and control of malaria. Over the years evidence has shown that traditional methods for diagnosing malaria remain problematic with a number of limitations. In this synoptic review an update of malaria diagnosis is presented and discussed highlighting the limitations and difficulties of both clinical (symptoms/ clinical signs-based) and laboratory (parasite-based) diagnosis of malaria. Enhancement of accurate malaria diagnosis is now more imperative than ever not only in the background of the current new era of malaria treatment with relatively expensive artemisinin-based combination therapies (ACTs); but more so in the heightened global campaign to effectively control; manage and possibly eradicate malaria from the face of the globe

Feeding and indoor resting behaviour of the mosquito Anopheles longipalpis in an area of hyperendemic malaria transmission in southern Zambia.

Anopheles longipalpis (Theobald) (Diptera: Culicidae) is a predominantly zoophilic mosquito that has not been implicated in malaria transmission. However, this species was collected indoors with An. funestus s.l. in southern Zambia, where transmission of Plasmodium falciparum is hyperendemic, and we initially misidentified it morphologically and molecularly as An. funestus s.l. The indoor resting density and blood-feeding behaviour of An. longipalpis were investigated during the 2004-05 and 2005-06 transmission seasons in Mufwafwi village in southern Zambia. Numbers of endophilic An. longipalpis increased towards the end of the rainy season. Although specimens were collected during human landing catches, the feeding behaviour of An. longipalpis was significantly biased towards cattle (88.7%), with other bloodmeals originating from dogs, goats and chickens. None of the 177 specimens of An. longipalpis were infected with P. falciparum. These data are consistent with existing reports that An. longipalpis is not involved in malaria transmission. However, more extensive sampling is necessary. Importantly, the correct identification of An. longipalpis is crucial for malaria control programmes in areas where An. funestus s.l and An. longipalpis exist sympatrically so that scarce resources are not wasted on the control of a non-vector.

Plasmodium falciparum transmission rate and selection for drug resistance: a vexed association or a key to successful control?

While malaria eradication campaigns once adopted a combination of vector control and chemotherapy to overcome the disease, today's opinion on the matter is equivocal. So what has changed? This paper reviews some of the confusing hypotheses on the relationship between Plasmodium falciparum transmission and levels of drug resistance. New field evidence showing variations of in vivo chloroquine resistance in relation to indoor residual spraying and natural endemicity patterns, is considered with a view to how these phenomena implicate on control.

Microsatellite markers reveal a spectrum of population structures in the malaria parasite Plasmodium falciparum.

Multilocus genotyping of microbial pathogens has revealed a range of population structures, with some bacteria showing extensive recombination and others showing almost complete clonality. The population structure of the protozoan parasite Plasmodium falciparum has been harder to evaluate, since most studies have used a limited number of antigen-encoding loci that are known to be under strong selection. We describe length variation at 12 microsatellite loci in 465 infections collected from 9 locations worldwide. These data reveal dramatic differences in parasite population structure in different locations. Strong linkage disequilibrium (LD) was observed in six of nine populations. Significant LD occurred in all locations with prevalence <1% and in only two of five of the populations from regions with higher transmission intensities. Where present, LD results largely from the presence of identical multilocus genotypes within populations, suggesting high levels of self-fertilization in populations with low levels of transmission. We also observed dramatic variation in diversity and geographical differentiation in different regions. Mean heterozygosities in South American countries (0.3-0.4) were less than half those observed in African locations (0. 76-0.8), with intermediate heterozygosities in the Southeast Asia/Pacific samples (0.51-0.65). Furthermore, variation was distributed among locations in South America (F:(ST) = 0.364) and within locations in Africa (F:(ST) = 0.007). The intraspecific patterns of diversity and genetic differentiation observed in P. falciparum are strikingly similar to those seen in interspecific comparisons of plants and animals with differing levels of outcrossing, suggesting that similar processes may be involved. The differences observed may also reflect the recent colonization of non-African populations from an African source, and the relative influences of epidemiology and population history are difficult to disentangle. These data reveal a range of population structures within a single pathogen species and suggest intimate links between patterns of epidemiology and genetic structure in this organism.

Diagnostic performance of two antigen capture tests for the diagnosis of Plasmodium falciparum malaria in Zimbabwe.

OBJECTIVE: The objective was to compare the diagnostic performance of two antigen capture tests, ParaSight-F test and Immunochromatographic test (ICT), for the diagnosis of Plasmodium falciparum malaria. DESIGN: A comparative study. SETTING: Burma Valley, Mutare District, Manicaland in Zimbabwe. SUBJECTS: Patients attending the local clinic with clinical signs and symptoms associated with malaria infection. A blood film was collected from the patient and at the same time blood for the ParaSight-F test and the ICT was collected too. A total of 123 patients were diagnosed using the ICT test, the ParaSight-F test and microscopy which was used as a "gold" standard. MAIN OUTCOME MEASURES: True positives and negatives, false positives and negatives with reference to microscopy. RESULTS: The results indicate that ICT had a higher sensitivity (100%) than the ParaSight-F test (93.94%) but showing a lower specificity. The specificity for ICT (75%) is lower than the ParaSight-F test (81.2%) because of the presence of circulating P. falciparum histidine-rich protein-2 (PfHRP-2) in blood even after two weeks post treatment. Two slides that were negative for ParaSight-F tests showed positive on microscopy. However, 21 and 12 slides which were negative on microscopy, showed positive with ICT and ParaSight-F respectively. The fact that ICT detects very low quantities of PfHRP-2 puts it at a comparative advantage because it detects positives even at very low parasite rates. CONCLUSION: The availability of these two antigen capture tests, which are easy to perform, will reduce the number of severe cases by providing early diagnosis. The tests will also reduce the number of unnecessary treatments and irrational use of antimalarials.

Status of chloroquine efficacy against falciparum malaria in the Mola area of Kariba district, Zimbabwe.

The therapeutic efficacy of chloroquine was assessed, during the 1997 transmission season, using 64 cases of uncomplicated, falciparum malaria originating from 18 villages in the Mola area of Kariba district, Zimbabwe. Chloroquine effected a modest reduction in asexual parasite density and clinical symptoms. The mean density of asexual parasites on day 3 post-treatment was 24.94% (95% confidence interval = 13.59%-36.30%) of that on day 0, and 78% of the patients followed-up for at least 1 week were free of parasitaemia on day 7. However, there was appreciable therapeutic failure. The early treatment failure rate (i.e. by day 3) was 21% and about 6% of the cases exhibited increasing asexual parasitaemia despite treatment. Late treatment failures (i.e. by day 14) occurred in 32% of the malaria cases, and 52% of the patients were ultimately considered failures. All the failures were successfully treated with sulfadoxine-pyrimethamine or quinine. Chloroquine therefore has declining parasitological and clinical value as the first-line, presumptive treatment for uncomplicated, falciparum malaria in the study area, necessitating strategies to cope with resistant cases. The proportion of the patients failing to be treated successfully with chloroquine, one of the largest reported in Zimbabwe to date, may-force major policy reviews in the near future. It is recommended that the second-line antimalarial, sulfadoxine-pyrimethamine, be distributed to health-centre level in the study area, backed up by the decentralised confirmation of diagnosis. Measures to deal with treatment failures at local health centres are proposed.

Post treatment sensitivity studies with the ParaSight-F test for malaria diagnosis in Zimbabwe.

The post-treatment diagnostic performance of the Plasmodium falciparum histidine-rich protein (HRP-II) antigen detection test, ParaSight-F test, was assessed on 55 falciparum malaria cases treated with chloroquine during in vivo drug sensitivity studies. The post-treatment sensitivity of the test remained high, except for an insignificant decline on day 1. However, specificity dropped sharply by day 1, subsequently increasing linearly with time to satisfactory values by day 10. As expected, from its inverse relationship to specificity, the false positive rate was high on day 1 and decreased linearly to low level by day 10. The temporary increase in false positive rate-following treatment was due to persistent parasite antigen, rather than subpatent parasitaemia. Thus findings showed that positive readings by the test within 10 days post-treatment may occur in cured cases and will not necessarily imply treatment failure. Furthermore it will be important to take patient antimalarial history into consideration during routine usage of the test for malaria diagnosis. The trend of Youden's J-index for the ParaSight-F test showed that from 10 days post-treatment, the test was generally reliable, with positive readings indicating active infection. It was concluded that the ParaSight-F test was not only valuable at confirming malaria diagnosis on clinical cases in seasonal transmission areas, but had potential for application to detect recrudescent infections within 2 weeks of chloroquine treatment.

Trial of the ParaSight-F test for malaria diagnosis in the primary health care system, Zimbabwe.

Rapid diagnosis of Plasmodium falciparum malaria remains one of the main limitations to prompt treatment. Diagnosis based on clinical symptoms is decidedly unreliable, especially in areas of seasonal transmission like Zimbabwe. In view of this, the Plasmodium falciparum histidine rich protein (HRP-II) antigen detection assay (ParaSight-F test) was tried at 10 health centres in 3 malaria endemicity zones of Zimbabwe, as a malaria diagnostic tool for primary health care. Parasitological evaluations were conducted using thick and thin film microscopy as gold standard, and ease of test operation and practicability to nurses were ascertained by questionnaire. The sensitivity of the test did not vary substantially by endemicity zone and was approximately 93%. Specificities were 85, 72 and 92% in the hyperendemic, mesoendemic and hypoendemic zones, respectively. Positive predictive values varied considerably with endemicity, the lowest being in the hypoendemic zone (56%). However, negative predictive values did not change significantly, with a mean of 94%. It was found that the ParaSight-F test reduced mistreatment for malaria, relative to clinical diagnosis, by up to 81%, especially in the hypoendemic region. Test acceptability evaluations were good.

Knowledge, practices, and perceptions about malaria in rural communities of Zimbabwe: relevance to malaria control.

A survey of 411 household heads was undertaken in Gokwe district, Zimbabwe, to assess villagers' knowledge, practices and perceptions about malaria and their implications for malaria control. Our results show that although the government has sustained an annual indoor insecticide spraying programme for over four decades, about 50% of respondents did not adequately understand its purpose, with 26% believing that the programme was intended to kill domestic pests, not including mosquitos. During the 1991-92 spraying cycle, 72% of the villagers had their homes sprayed. However, 21% of such villagers refused to have some rooms in their homes sprayed. Householders' understanding of the function of the spraying programme was significantly related to their compliance with it (P < 0.05). A total of 82% of respondents reported not taking any measures to protect themselves from malaria. Taking preventive measures was significantly related to knowledge of the causes of malaria (P < 0.05). The study shows the importance of involving communities in a control programme intended to be to their benefit and of informing them about available options for protection against malaria.

PIP: 411 household heads in Gokwe district, Zimbabwe, were surveyed to gain insight into villagers' knowledge, practices, and perceptions about malaria and their implications for malaria control. The survey found that while the government has sustained an annual indoor insecticide spraying program for more than four decades, about half of the respondents did not fully understand its purpose. Fully 26% believed that the program was designed to kill domestic pests, not including mosquitoes. During the 1991-92 spraying cycle, 72% of the villagers had their homes sprayed. 21% of the villagers, however, refused to have some rooms in their homes sprayed. Homeowners' understanding of the purpose of the spraying program was significantly related to their compliance with it. 82% of respondents reported not taking any measures to protect themselves from malaria. Taking preventive measures was significantly related to one's knowledge of the causes of malaria. These findings point to the need to thoroughly explain to communities what malaria is and how it can be prevented. Furthermore, communities must be involved in any given malaria control program to ensure their understanding and compliance.

A case of dual chloroquine and halofantrine treatment failure in Zimbabwe.

A case of malaria treatment failure with chloroquine and halofantrine is reported. The likely determinants and policy considerations are addressed.

Response of chloroquine-resistant falciparum malaria to sulfadoxine/pyrimethamine in Gokwe area of Zimbabwe.

Parasitaemia was monitored in vivo on 182 chloroquine-resistant falciparum malaria infections of Gokwe district treated with sulfadoxine/pyrimethamine. Asexual parasitaemia was cleared by day seven in 181 of the 182 patients, while in one, low level parasitaemia persisted beyond day seven post treatment. Late RI recrudescence occurred in five (3 pc) of the infections after initial clearance by day seven. Of the 182 malaria patients, 27 had not taken chloroquine two weeks prior to treatment with sulfadoxine/pyrimethamine (criterion for WHO in vivo drug sensitivity test subjects). Asexual parasite clearance was 100 pc in these patients by day six post treatment (mean time to parasite clearance 2.3 +/- 1.00 days). Recrudescence did not occur in two of the patients followed up on day 14 and in one followed up on day 21. This study showed that sulfadoxine/pyrimethamine was still an efficacious drug at clearing asexual parasitaemia within seven days on chloroquine resistant falciparum malaria in Gokwe district.

Chloroquine-resistant falciparum malaria in an area of rising endemicity in Zimbabwe.

Response of Plasmodium falciparum to chloroquine treatment was assessed in vivo in 219 malaria cases from eight villages in a formerly hypoendemic area of Zimbabwe experiencing a malaria outbreak. Seven (3%) of the cases were fully sensitive to chloroquine while 182 (83%) exhibited chloroquine-resistant responses. Of the 182 chloroquine-resistant cases 74 (41%) showed RI resistance while 108 (59%) exhibited RII-RIII resistance. In-vivo follow-up was not completed to Day 28 in the remaining 30 (14%) of the malaria cases, which were therefore either fully sensitive or RI resistant. In 23 (11%) of the malaria cases pyrexia and increasing parasitaemia occurred between Day 3 and Day 7 after treatment. Mean parasite clearance time was 5.8 days (s.d. 2.89 days) in patients who were cleared of asexual parasitaemia. In all but 1 (0.5%) of the chloroquine-resistant infections, asexual parasites were cleared by Day 7 following treatment with the sulphadoxine/pyrimethamine combination (Fansidar). This study showed an acute problem of chloroquine resistance in an area of Zimbabwe. It is recommended that the drug policy be modified to allow distribution of limited stocks of Fansidar to the local clinics for restricted use on documented chloroquine treatment failures within 7 days.

A comparative study of the schizontocidal efficacy and safety of artemether versus chloroquine in uncomplicated malaria.

Forty-seven patients with uncomplicated falciparum malaria were randomly assigned to receive either artemether (n = 24), 9.6 mg/kg body weight intramuscularly over five days or chloroquine (n = 23), 25 mg/kg body weight orally. Patients were kept in hospital for seven days followed by review on days 14, 21 and 28. Five patients on chloroquine were withdrawn before day seven due to treatment failure. Of the remaining patients, parasite clearance time was 33.0 +/- 13.6 hours for the artemether group and 63.3 +/- 14.7 hours for patients on chloroquine (p < 0.001). No significant difference was recorded in fever clearance time between the two groups of patients. Recrudescence rate for patients on artemether was 14.3 pc compared to 57.1 pc for the chloroquine group (p < 0.05). No major adverse events were recorded for either treatment group although five patients on artemether had a transient spike of temperature after clearance of parasitaemia. In conclusion, our study has shown that no major adverse events were experienced by patients on artemether and the rate of parasite clearance for the artemether group was superior to that of patients on chloroquine.

Malaria and anaemia in pregnancy in Gokwe communities ; Zimbabwe

Using an analytical case control study; five hundred and sixty pregnant women attending antenatal care (ANC) at 12 preselected health centres in Gokwe district during the peak malaria transmission season were screened for malaria and anaemia using the blood slide method and Spencer haemoglobinometer; respectively. One of the findings was that there was highly significant association between malaria infection and anaemia both in primigravidae and multigravidae. Across parity groups; prevalence of anaemia in malaria-infected pregnant women was more than 3 times that in uninfected pregnant women. Relative risk for anaemia associated with malaria in pregnancy was 4.1 as estimated using the odds ratio