[Analysis of different clinical criteria in malaria patients in Papua New Gwinea]

To assess the validity of different clinical criteria in malaria patients, a small study including 92 children presented with fever or history of fever were examined in a highly endemic area of Papua New Gwinea. In 21 children parasitaemia was confirmed by microscopy examination of thick and thin smear stained with Giemsa method (9 cases of Plasmodium falciparum, 8 cases of Plasmodium vivax and 4 cases of mixed invasion Plasmodium falciparum and Plasmodium vivax). Only 4 from different 39 criteria analyzed in children with history of fever or hot skin showed significant association with parasitaemia (conscious disturbances, severe wasting, enlarged spleen and diarrhoea), however none of the criteria presented high sensitivity and could serve as good predictors for parasitaemia accept two (first and second one). These findings help to realize the importance of laboratory examination in diagnosis of malaria and explain difficulties in confirming or exclusion of malaria where microscopy is not available.

The community-based malaria control programme in Tigray, northern Ethiopia. A review of programme set-up, activities, outcomes and impact

Tigray, the northernmost state of Ethiopia, has a population of 3.5 million, 86% rural, and 56% living in malarious areas. In 1992 a Community-Based Malaria Control Programme was established to provide region-wide and sustained access to early diagnosis and treatment of malaria at the village level. 735 volunteer community health workers (CHWs) serve 2,327 villages with a population of 1.74 million, treating an average of 489,378 patients yearly from 1994 to 1997. Recognition of clinical malaria is similar for CHWs and health staff at clinics where there is no access to microscopy. In 1996 a pilot community-financing scheme of insecticide-treated bednets was well accepted, but re-impregnation rates fell in 1998 because of war-related social upheaval. Indicators from health institutions show a progressive increase in malaria morbidity from 1994 to 1998. Repeated mortality surveys show a 40% reduction in death rates in under-5 children from 1994 to 1996 and a 10% increase from 1996 to 1998. These trends may be related to increased malaria transmission with water resources development, increased seasonal labour migration to malarious lowlands, prolongation of the transmission season with climate changes, and increasing chloroquine resistance throughout Ethiopia. Progressive extension of CHW services to ensure better coverage of women, children, migrant workers and communities near water development projects, change to first-line treatment with sulfadoxine-pyrimethamine, extension of the impregnated bednet initiative, and development of a regional warning system for epidemics should result in a greater impact on morbidity and mortality.

Field evaluation of the ICT malaria P.f/P.v immunochromatographic test for diagnosis of Plasmodium falciparum and P.vivax infection in forest villages of Chhindwara, central India

A rapid new immunochromatographic test (ICT malaria P.f/P.v) for diagnosis of Plasmodium falciparum and P.vivax was evaluated against thick blood smears in forest villages of Chhindwara, Madhya Pradesh, where both Plasmodium falciparum and P.vivax are prevalent. 344 symptomatic patients (Gond ethnic tribe) in five villages were screened by field staff of the Malaria Research Centre in October 1999. For P.falciparum, the ICT was 97.5% sensitive and 88% specific, with a positive predictive value (PPV) of 87.6% and a negative predictive value (NPV) of 97.6%. For P.vivax the sensitivity was only 72%, the specificity 99%, with a PPV of 92% and an NPV of 96%. Although a negative test result was inadequate to exclude parasitaemia < or = 300/microl for P.falciparum and < or = 1500/microl for P.vivax, the test is potentially useful in remote areas.

Relapse pattern of Plasmodium vivax in Mumbai: a study of 283 cases of vivax malaria

OBJECTIVES

To analyze the relapse pattern of Plasmodium vivax in the city of Mumbai.

METHODS

283 cases of smear positive vivax malaria were treated with full dose (25 mg/kg) chloroquine and were asked to follow up for at least one year. None of the patients received primaquine.

RESULTS

Of the 150 cases who followed up for at least one year, 19 relapsed, 17/19 relapsed within the first 6 months; indicating that the relapse pattern in the city is predominantly of the tropical or Chesson strain type.

CONCLUSIONS

Vivax malaria patients should be monitored for at least six months. Those who do relapse should receive treatment with full dose chloroquine and 14 days of primaquine treatment.

Malaria diagnosis with the haematology analyser Cell-Dyn 3500: What does the instrument detect?

The Cell-Dyn 3500 instrument could become a sensitive and specific tool in the diagnosis of malaria. The instrument appears to detect malaria-pigment within monocytes and granulocytes. A case of P. vivax malaria in a patient with increased osmotically resistant erythrocytes illustrates the potential of the instrument to detect intraerythrocytic parasites with pigment. However, in most malaria-patients with normal red cell osmotic resistance the observed phenomena seem rather to represent intraleukocytic pigment. This can remain in the circulation of clinically and parasitologically cured individuals and thus may not indicate acute infection. While the instrument can indicate those patients who have been infected a diagnosis of acute malaria must be established independently.

Evaluation & usefulness of a immunochromatographic test for rapid detection of Plasmodium falciparum infection

Rapid test (Parachek Pf) based on detection of HRP-2 protein specific to Plasmodium falciparum by immunochromatographic technique was evaluated. Prevalence of infection was 8.5%. The test was 100% sensitive & 99.5% specific on comparison with light microscopy. The test is useful for making 'on the spot' diagnosis.

Performance of the OptiMAL assay for detection and identification of malaria infections in asymptomatic residents of Irian Jaya, Indonesia

The OptiMAL assay, a new immunochromatographic "dipstick" test for malaria based on detection of Plasmodium lactate dehydrogenase (pLDH), is purported to detect infections of approximately 200 parasites/microL of blood and to differentiate between Plasmodium falciparum and non-P. falciparum. We evaluated OptiMAL performance by comparing the test strip interpretations of two independent readers with consensus results obtained independently by expert malaria microscopists. Unbiased measures of sensitivity were derived by applying the OptiMAL test for detection and differentiation of light, asymptomatic infections by P. falciparum and Plasmodium vivax. OptiMAL readings were separated in time to determine whether the reaction signal was stable. Microscopy identified infections in 225 of 505 individuals screened; those with P. falciparum (n = 170) averaged 354 asexual forms/microL and P. vivax/Plasmodium malariae (n = 112) averaged 216 asexual forms/microL of blood. Concordance between OptiMAL and microscopy was 81% and 78% by the two independent readings. The assay's sensitivity for detection of any malaria species was 60.4% and 70.2% respectively and specificity was 97% and 89%. Most cases identified by microscopy as P. falciparum were graded as negative or non-falciparum by both OptiMAL readers. OptiMAL false negatives as well as misidentifications were related to low parasitemias (< 500/microL). The OptiMAL assay demonstrated 88-92% sensitivity for detecting infections of 500-1,000 parasites/microL, a range covering the mean parasitemia of primary symptomatic P. falciparum infections in malaria-naïve Indonesian transmigrants. This device was markedly less sensitive than expert microscopy for discriminating between malaria species and is presently unsuited for use as an epidemiological screening tool. The OptiMAL assay is not approved for diagnostic use but is commercially available for research purposes only.

Recurrent malaria--an enigma?

Management of recurrent malaria has to be individualised. A careful history, details of the drugs received, family history, laboratory evaluation will definitely help us in arriving at a reasonable diagnosis. For the future, genotyping, PCR testing and gamma interfiron levels may help us in identifying causes for recurrences.

Infectious disease challenges in immigrants from tropical countries

BACKGROUND

In today's mobile society, international travel and immigration are becoming increasingly more common. This poses an additional challenge to the clinician to expand the differential diagnosis to include diseases endemic to the area of travel.

OBSERVATION

We present a case of malaria and tuberculosis in a 16-year-old African male immigrant. He had several encounters with the health care system for complaints of nonspecific symptoms for which he was treated with antibiotics without follow-up.

CONCLUSION

Clinicians should take a complete history and expand their differential diagnosis to include diseases endemic to the country of origin and/or travel when treating an international patient. This not only will allow prompt treatment of the patient's condition but also will address public health concerns.

Impact of the oil industry on malaria diagnosis and management in north-east Scotland (1992-99)

In order to assess the current pattern of malaria presenting to the Aberdeen Infection Unit a retrospective casenote review was undertaken of 110 patients admitted with that diagnosis between 1st January 1992 and 31st August 1999. Oil-related work was the reason for travel in 48 (43.6%) of the UK residents, holiday in 35 (31.8%), backpacking in 8 (7.3%) and other work in 5 (4.5%). Sixty-five patients (59.1%) had PL falciparum malaria (pure or mixed), 25 (22.7%) had PL vivax, 6 (5.4%) PL ovale and 3 (2.7%) PL malariae infection. No prophylaxis had been taken by 66% of the 47 UK-based oil workers and by 36% of the other 48 UK residents who had returned from Africa. There is a need for better education of oil workers and holidaymakers travelling to areas endemic for malaria. We are now setting up a travel advisory service in our Unit to address the problem.

Performance of the OptiMAL malaria antigen capture dipstick for malaria diagnosis and treatment monitoring at the Hospital for Tropical Diseases, London

We report here the sensitivity and specificity of OptiMAL for the diagnosis of acute malaria in patients presenting to the Hospital for Tropical Diseases (HTD), a tertiary referral centre for Tropical and Infectious diseases. A sensitivity of 95.3% and a specificity of 100% for Plasmodium falciparum and a sensitivity of 96% and a specificity of 100% for Plasmodium vivax was obtained. The ability to follow the course of the parasitaemia using OptiMAL during treatment and its significance for use in areas where expert microscopy is not available is discussed.

Clinical and parasitological appraisal of patients with imported malaria

The study group comprised 118 patients suspected of malaria who underwent an examination following their return to Poland from the tropical countries. Evaluation of the admitted patients was based on epidemiological, clinical and parasitological criteria. The obtained data allowed to confirm acute malaria in 20 patients (16.9%) and malaria in the past, in 32 patients (27.1%). In the remaining 65 patients (55.1%) we excluded malaria. Malaria caused by P. vivax was confirmed in 5 patients, by P. falciparum in 9 patients. A mixed invasion was diagnosed in 6 patients including: P. falciparum and P. vivax in 3 cases; P. vivax, P. ovale and P. malariae in 2 cases; P. falciparum, P. vivax and P. ovale in 1 patient. We noted no relationship between the severity of the clinical course and IFA results. It was found an atypical clinical course of malaria and diagnostic difficulties in patients who used chemosuppression for malaria prophylaxis.

Malaria and Borrelia co-infection

Severe anemia requiring blood transfusion may complicate falciparum malaria, but is rare in nonfalciparum malaria. We present a case of a young man with high fever, severe hemolytic anemia, and a blood film containing massive co-infection with Plasmodium vivax and with Borrelia. The possible importance of the co-infection on the magnitude of hemolysis will be discussed.

Random distribution of mixed species malaria infections in Papua New Guinea

Plasmodium falciparum (Pf), P. vivax (Pv), P. malariae (Pm), and P. ovale (Po) infections are endemic in coastal areas of Papua New Guinea. Here 2,162 individuals living near Dreikikir, East Sepik Province, have been analyzed for complexity of malaria infection by blood smear and polymerase chain reaction (PCR) diagnoses. According to blood smear, the overall prevalence of Plasmodium infection was 0.320. Most individuals (0.283) were infected with a single species only. The prevalence of mixed species infections was low (0.037). Further analysis of a 173-sample subset by nested PCR of small subunit ribosomal DNA resulted in an overall 3.0-fold increase in prevalence of infection, with a 17.5-fold increase in the frequency of mixed species infections. Among mixed species infections detected by PCR, the frequency of double species was 0.364, and that of triple species was 0.237. Nine individuals (0.052) were infected with all 4 species. To determine if infection status (uninfected, single, and multiple infections) deviates from an independent random distribution (null hypothesis), observed versus expected frequencies of all combinations of Plasmodium species infections, or assemblages (Pf-, Pv-, Pm-, Po-, to Pf+, Pv+, Pm+, Po+), were compared using a multiple-kind lottery model. All 4 species were randomly distributed whether diagnosed by blood smear or PCR in the overall population and when divided into age group categories. These findings suggest that mixed species malaria infections are common, and that Plasmodium species appear to establish infection independent of one another.

[Increase of malaria among migrants in Amsterdam-Zuidoost]

In a general practice in Amsterdam Southeast in 1998 a delayed first attack of Plasmodium ovale infection was diagnosed in a 13-year-old girl from Ghana, malaria tropica with a low parasitaemia index in a 43-year-old Ghanaian man and a 8-year-old Ghanaian girl, and Plasmodium vivax infection in a 44-year-old Surinam woman. The Ghanaian patients had visited their native country, the Surinam woman had contracted the infection during a visit to India. All patients responded well to antimalaria medication. These patients were among a total of 6 patients of non-Dutch origin diagnosed with malaria in 1998 in this general practice. Four patients had not taken any prophylactic drug and two had not used the drugs properly. A relative increase of malaria in immigrants has been seen in the Netherlands and elsewhere in Europe in recent years. Underestimation of the risks and lack of knowledge of malaria and of the changing epidemiology make people of ethnic minorities travel without taking appropriate precautions. New, creative ways of communication and information will have to be explored to reach these migrant communities.

[Malaria in travelers returning to Israel from endemic areas: diagnosis of two patients in a family practice]

2 cases of malaria in family practice are described in a 26- and a 50-year-old woman. Both probably could have been prevented had common chemoprophylactic drugs been taken. The risk of malaria is greater than the risk of possible side-effects of the drugs commonly used by travelers for prevention. Family physicians must be aware of the possibility of malaria in young people with fever, especially those who have travelled to equatorial areas and special attention should be given to encourage chemoprophylaxis.

Hidden Plasmodium falciparum infections

Mixed infection of P. vivax and P. falciparum malaria frequently recorded in field survey. However mixed infection was frequently misdiagnosed as single infection due to low parasite density, difficult species identification and procedure error of microscopic examination. Our previous report showed high rates (32-33%) of P vivax infection following treatment of previously assumed to be only P. falciparum infection. In a study of 992 patients with initial presentation with P. falciparum, we found that 104 (10.5%) of patients had P. falciparum appearing during 28 days in the hospital (ranged 1-28 days) following chloroquine treatment for P. vivax. The potential for P. falciparum appearing following elimination of P. vivax must be considered in malaria treatment.

Comparison of the OptiMAL test with PCR for diagnosis of malaria in immigrants

The OptiMAL test (Flow Inc., Portland, Oreg.), which detects a malaria parasite lactate dehydrogenase (pLDH) antigen, has not been evaluated for its sensitivity in the diagnosis of malaria infection in various epidemiological settings. Using microscopy and a PCR as reference standards, we performed a comparison of these assays with the OptiMAL test for the detection of Plasmodium falciparum and Plasmodium vivax infection in 550 immigrants who had come from areas where malaria is endemic to reside in Kuwait, where malaria is not endemic. As determined by microscopy, 125 (23%) patients had malaria, and of these, 84 (67%) were infected with P. vivax and 36 were infected with P. falciparum; in 5 cases the parasite species could not be determined due to a paucity of the parasites. The PCR detected malaria infection in 145 (26%) patients; 102 (70%) of the patients had P. vivax infection and 43 had P. falciparum infection. Of the five cases undetermined by microscopy, the PCR detected P. falciparum infection in two cases, P. vivax infection in two cases, and mixed (P. falciparum plus P. vivax) infection in one case. Correspondingly, the OptiMAL test detected malaria infection in 95 patients (17%); of these, 70 (74%) had P. vivax infection and 25 were infected with P. falciparum. In this study, 61 (49%) of the 125 malaria cases, as confirmed by microscopy, had a degree of parasitemia of <100 parasites per microl, and 23 (18%) of the cases had a degree of <50 parasites per microl. Our results show that the sensitivity of the OptiMAL test is high (97%) at a high level of parasitemia (>100 parasites/microl) but drops to 59% when the level is <100 parasites/microl and to 39% when it is <50 parasites/microl. In addition, the OptiMAL test failed to identify four patients whose blood smears contained P. falciparum gametocytes only. We conclude that the sensitivity and specificity of the OptiMAL test are comparable to those of microscopy in detecting malaria infection at a parasitemia level of >100 parasites/microl; however, the test failed to identify more than half of the patients with a parasitemia level of <50 parasites/microl. Thus, the OptiMAL test should be used with great caution, and it should not replace conventional microscopy in the diagnosis of malaria infection.

Hypohaptoglobinaemia as a biochemical and epidemiological marker of falciparum malaria

OBJECTIVES

The study was conducted in two parts to find out the usefulness of hypohaptoglobinemia (Hpo) as a biochemical and epidemiological marker of malaria. Part-I study was conducted in a Medical College Hospital to find out Hpo in malaria and the time required for normalization of Hpo. Part-II study was undertaken in two endemic areas of malaria to find out the prevalence of Hpo and haptoglobin index (HI) throughout the year along with other indicators of malaria.

METHODS

In Part-I study, 172 patients of malaria constituting 58, 52 and 62 patients of cerebral malaria, uncomplicated falciparum malaria and vivax malaria, respectively were enrolled. Along with routine haematological and biochemical investigations, haptoglobin (Hp) estimation was done by endoplate haptoglobin test kit on admission and at 15 days interval for 3 months. In Part-II study Hp was estimated is 305 subjects in two endemic areas of malaria. HI, parasitic index, slide positivity rate (SPR), slide falciparum rate (SFR) were estimated throughout the year and HI was compared with these epidemiological markers.

RESULTS

Hpo was present in 102 (92.7%) cases of falciparum malaria which was significantly more than vivax malaria and non-malarial fever. The normalisation of Hpo took about a month or more. The incidence of Hpo was 32.1% is endemic and 4.7% in nonendemic area of malaria. The HI varied between 12.4 to 25.2% throughout the year and was found to be a better marker than other classical markers of malaria.

CONCLUSION

Hypohaptoglobinemia may be considered as a useful indirect indicator of falciparum malaria. HI can be used as an epidemiological maker which is better than classical markers of malaria used at present.

Case studies in international travelers

Family physicians should be alert for unusual diseases in patients who are returning from foreign travel. Malaria is a potentially fatal disease that can be acquired by travelers to certain areas of the world, primarily developing nations. Transmitted through the bite of the Anopheles mosquito, malaria usually presents with fever and a vague systemic illness. The disease is diagnosed by demonstration of Plasmodium organisms on a specially prepared blood film. Travelers can also acquire amebic infections, which may cause dysentery or, in some instances, liver abscess. Amebiasis is diagnosed by finding Entamoeba histolytica cysts or trophozoites in the stool. Invasive amebic infections are generally treated with metronidazole followed by iodoquinol or paromomycin. Cutaneous larva migrans is acquired by skin contact with hookworm larvae in the soil. The infection is characterized by the development of itchy papules followed by serpiginous or linear streaks. Cutaneous larva migrans is treated with invermectin or albendazole. Case studies are presented.

Field evaluation of the ICT malaria P.f/P.v immunochromatographic test for detection of Plasmodium falciparum and Plasmodium vivax in patients with a presumptive clinical diagnosis of malaria in eastern Indonesia

In areas such as eastern Indonesia where both Plasmodium falciparum and Plasmodium vivax occur, rapid antigen detection tests for malaria need to be able to detect both species. We evaluated the new combined P. falciparum-P. vivax immunochromatographic test (ICT Malaria P.f/P.v.) in Radamata Primary Health Centre, Sumba, Indonesia, from February to May 1998 with 560 symptomatic adults and children with a presumptive clinical diagnosis of malaria. Blinded microscopy was used as the "gold standard," with all discordant and 20% of concordant results cross-checked blindly. Only 50% of those with a presumptive clinical diagnosis of malaria were parasitemic. The ICT Malaria P.f/P.v immunochromatographic test was sensitive (95. 5%) and specific (89.8%) for the diagnosis of falciparum malaria, with a positive predictive value (PPV) and a negative predictive value (NPV) of 88.1 and 96.2%, respectively. HRP2 and panmalarial antigen line intensities were associated with parasitemia density for both species. Although the specificity and NPV for the diagnosis of vivax malaria were 94.8 and 98.2%, respectively, the overall sensitivity (75%) and PPV (50%) for the diagnosis of vivax malaria were less than the desirable levels. The sensitivity for the diagnosis of P. vivax malaria was 96% with parasitemias of >500/microl but only 29% with parasitemias of <500/microl. Nevertheless, compared with the test with HRP2 alone, use of the combined antigen detection test would reduce the rate of undertreatment from 14.7 to 3.6% for microscopy-positive patients, and this would be at the expense of only a modest increase in the rate of overtreatment of microscopy-negative patients from 7.1 to 15. 4%. Cost remains a major obstacle to widespread use in areas of endemicity.

A comparison of antigen dipstick assays with polymerase chain reaction (PCR) technique and blood film examination in the rapid diagnosis of malaria

Early diagnosis of malaria for military personnel training in the field is crucial in providing proper treatment for the infected and in taking appropriate preventive measures for the non-infected. Present preliminary diagnosis of malaria in the field depends on the clinical symptoms of the patients and there is a need for rapid diagnosis of malaria in the field. The presence of drug-resistant strains of the Plasmodium species in the region also increases the urgency of finding a quick and sensitive way of identifying the different strains. This study evaluated current methods available for the diagnosis of Plasmodium falciparum and Plasmodium vivax. The dipstick assays, the ParaSight F test and the OptiMAL malaria rapid test were compared with the methods of microscopic examination of blood film and polymerase chain reaction (PCR). On comparison to the blood film and PCR methods, the ParaSight F test has specificity of 98.6% and sensitivity of 91% for P. falciparum detection. The OptiMAL malaria rapid test has a specificity of 100% and 98.6% and sensitivity of 92.8% and 92.6% for P. vivax and P. falciparum detection respectively. We conclude that both tests are suitable for use for rapid malaria diagnosis in the field but the OptiMAL rapid malaria test, which can detect both vivax and falciparum malaria, would be more useful.

Clinical case definition of malaria at a secondary level hospital in northern India

Malaria has re-emerged as a major public health problem in India. At present, under the National guidelines; all fevers are presumed to be due to malaria and chloroquine is given as presumptive treatment. This results in overtreatment. We did a pilot study to see whether some clinical predictors of malaria could be identified in the Indian setting. This case control study was done in a secondary level hospital. All those with fever who were smear positive for malaria were enrolled as cases and other patients fever who were smear negative for malaria served as the controls. All the factors under study were ascertained by a history or detailed clinical examination. A total of 41 cases and 95 controls were enrolled. Of the 41 cases, 35 were positive for P. vivax and six were positive for P. falciparum. After multivariate analysis, only splenomegaly (OR = 2.11; 95% CI = 1.27-3.50) and pallor (OR = 2.01; 95% CI = 1.16-3.48) were significantly associated with malaria. It appears that history of fever along with one or both of these two signs can be a useful predictor of malaria in a secondary level hospital in India. The utility and feasibility of a similar approach in a field setting needs to be studied further.

[Diagnostic and therapeutic difficulties with tertian malaria]

Diagnosis of malaria tertiana is not uncommonly missed or delayed because of a long incubation period, relapses after an unnoticed primary attack or due to suppressed parasitemia under antibiotics or antimalarials. The presently available rapid tests are not suitable for diagnosis of malaria tertiana. Malaria tertiana acquired in Southeast Asia carries a considerable risk of resistance to chloroquine. In this situation mefloquine is used in first place at total dose of 1000-1500 mg. Relapse of malaria tertiana even after primaquine have been described in travellers returning from the tropics. The efficacy of primaquine can be improved by raising the dose. Hereby an increased risk of hemolysis in concomitant glucose-6-phosphate-dehydrogenase deficiency and, more commonly, gastrointestinal side effects have to be considered.

Acridine orange stained blood wet mounts for fluorescent detection of malaria

The age old Romanowsky stained thick blood smear examination for malarial parasites may fail to reveal the low parasitaemia. The commercial 'QBC' like acridine orange stained capillary tube preparation has a limitation of precise species identification and the detection of extra-erythrocytic parasites. Hence, the present study was aimed to improve malarial parasite detection by using acridine orange to stain large blood drops in the form of wet coverglass mounts. The acridine orange stained blood wet mounts over 2420 suspected malaria cases from Indore city were examined under fluorescent microscope and the results compared with the Leishman's stained thick blood smears in a blind study. The positivity of malarial parasites reported by the modified acridine orange staining was 248 against 109 by Leishman's stained thick blood smears. The modified acridine orange stained method is simple, instant and more efficient, requires less scanning time and skill, allows scanning of larger blood volume (75 ul) at lower magnification and the morphological details at higher magnification helps to make the precise species identification.

[Imported malaria in the Kabardino-Balkarian Republic]

Forty-three cases of imported vivax malaria were notified in the Republic of Kabardino-Balkaria in 1981-1997. These included 40 military men serving in Afghanistan, a citizen from this country, a student of the Kabardino-Balkaria State University, a student of a Nal'chik technological college, and a newcomer from Armenia. Among the patients, urban and rural residents were 27.9 and 72.1%, respectively. 37.2% were detected in the season of effective mosquito infection; new cases of malaria were identified in 41.9%, relapses were found in 58.1% of patients. Analyzing the reasons of late diagnosis of imported malaria suggests that the patients visited health facilities too late due to their poor awareness of a risk for malaria. Out of 43 patients, 62.8% referred to in the first 3 days after the onset, 18.6, 9.3, 9.3, and 2.3% did on days 4-6, 7-15, 16, and after a month, respectively. Their physicians made diagnostic errors in 53% of cases. Acute respiratory disease, influenza, pneumonia, and hepatitis were most commonly diagnosed. They were found in 27.9, 11.6, 4.7, and 4.7%, respectively.

A controlled study on haemograms of malaria patients in Calcutta

A study was carried out at the Urban Health Centre, Chetla, Calcutta to evaluate the efficacy of quantitative buffy coat (QBC) analysis of haemograms in malaria patients suffering from fever with bodyache and chill and/or rigour attending the Fever Treatment Depot during a three months period (March-June 1996) who had undergone both malaria parasite study and haematological investigation by the QBC method from blood samples collected by finger prick. To avoid bias, malaria parasite studies and haemograms were done separately, and investigators were kept 'blind' about the results of other investigations. The haematological findings obtained of 180 slide-positive malaria cases were compared with a sample of 177 age- and sex-matched slide-negative controls selected by random sampling. The results revealed that haemoglobin levels (g%), haematocrit values (%), WBC and platelet counts of malaria cases were significantly lower than in the matched controls. Thus, QBC estimation correlates well with existing knowledge about malarial haematology. This relatively easier, quicker and reliable method of taking haemograms may be recommended for field testing for assessing haematological parameters of malaria cases under field conditions, before its introduction for large-scale use.

Semi-nested, multiplex polymerase chain reaction for detection of human malaria parasites and evidence of Plasmodium vivax infection in Equatorial Guinea

A semi-nested, multiplex polymerase chain reaction (PCR) based on the amplification of the sequences of the 18S small subunit ribosomal RNA (ssrRNA) gene was tested in a field trial in Equatorial Guinea (a hyperendemic focus of malaria in west central Africa). The method uses a primary PCR amplification reaction with a universal reverse primer and two forward primers specific for the genus Plasmodium and to mammals (the mammalian-specific primer was included as a positive control to distinguish uninfected cases from inhibition of the PCR). The second amplification is carried out with the same Plasmodium genus-specific forward primer and four specific reverse primers for each human Plasmodium species. The PCR amplified products are differentiated by fragment size after electrophoresis on a 2% agarose gel. Four villages from three regions of the island of Bioko (Equatorial Guinea) and two suspected Plasmodium vivax-P. ovale infections from the hospital of Malabo were tested by microscopy and PCR. The PCR method showed greater sensitivity and specificity than microscopic examination and confirmed the existence of a focus of P. vivax infections in Equatorial Guinea suspected by microscopic examination. It also provided evidence of several mixed infections, mainly P. falciparum and P. malariae, the two predominant species causing malaria in Equatorial Guinea.

[Diagnostic test to identify human Plasmodium species by the quantitative buffy coat test]

The quantitative buffy coat system (QBC Test) was designed for rapid diagnosis of malaria by identifying the presence of hemoparasites. The main drawback of the technique is failure to identify the Plasmodium species. The purpose of this study was to attempt to remedy this problem by studying the distribution of the parasites at the bottom of the test tube. Indeed since the QBC Test is based on gradient centrifugation of blood components, the distribution of the parasites in the test tube depends on density. Blind QBC Tests were performed on specimens obtained from two different batches, i.e., one from France and the other from Burkina Faso. Distribution curves were obtained by counting the number of parasites in all microscopic fields in the five-millimeter test tube. Our findings showed differences in distribution curve depending on species. For Plasmodium falciparum, the number of parasites was nearly the same in all fields suggesting that the arrangement of the parasites in the QBC Test tube was linear. For Plasmodium vivax and Plasmodium ovale, the number of parasites was markedly lower near the cap of the tube suggesting that a non-linear arrangement with a decreasing number of parasites toward the top of the tube. In 97 p. 100 of cases, we were able to propose a differential diagnosis of Plasmodium falciparum versus Plasmodium vivax or Plasmodium ovale. However it was not possible to distinguish between Plasmodium vivax and Plasmodium ovale. In case of mixed infection it would be difficult to distinguish Plasmodium falciparum from the other species. The ability to identify Plasmodium species would add to the advantages of the rapid and sensitive QBC Test.

Immunocapture diagnostic assays for malaria using Plasmodium lactate dehydrogenase (pLDH)

We have developed two diagnostic assays based on the specific detection of Plasmodium lactate dehydrogenase (pLDH) activity. These assays exploit a panel of monoclonal antibodies that capture the parasite enzyme and allow for the quantitation and speciation of human malaria infections. An immunocapture pLDH activity assay (ICpLDH) allows for the rapid purification and measurement of pLDH from infected blood using the NAD analog APAD, which reacts specifically with Plasmodium LDH isoforms. An immunochromatographic test (the OptiMAL assay) was also formatted and allowed the detection of parasite infections of approximately 200 parasites/microl of blood. By using a combination of antibodies, both tests can not only detect but differentiate between P. falciparum and non-P. falciparum malaria. Both assays show a sensitivity comparable with other commercial nonmicroscopic tests; importantly, we found very few instances of false-positive samples, especially with samples from patients recently cleared of malaria infection. Furthermore, we find that when one uses the quantitative ICpLDH assay, the levels of pLDH activity closely mirror the levels of parasitemia in both initial diagnosis and while following patient therapy. We conclude that diagnostic tests based on the detection of pLDH are both sensitive and practical for the detection, speciation, and quantitation of all human Plasmodium infections and can also be used to indicate drug-resistant infections.