S. B. Squire

The operation, quality and costs of a district hospital laboratory service in Malawi.

Laboratory services are run down in many low-income countries, severely constraining their input to patient care and disease surveillance. There are few data about the quality and cost of individual components of the laboratory service in poorer countries, yet this information is essential if optimal use is to be made of scarce resources. Staff time, range of tests, workload, and safety procedures were monitored over 12 months (1997-98) in a typical district hospital laboratory in Malawi. Data were collected to calculate the total economic cost of these services. Of the 31203 tests performed, 84% were to support blood transfusion and diagnosis of malaria and tuberculosis (TB). Test quality was reasonable for malaria and TB microscopy and blood transfusion, but poor for haemoglobin estimation. The cost per test ranged from US dollars 0.35 for haemoglobin to US dollars 11.7 per unit of blood issued and the total annual cost of the laboratory service was US dollars 32618. Blood transfusion and microscopy for malaria and TB comprised the majority of tests. Ensuring that these tests are of the highest quality will therefore have the most impact in reducing wastage of laboratory resources. Inadequate quality of haemoglobin estimations is a particular problem. The findings of this study are likely to be relevant to other low-income countries with similar disease burdens.

Pneumocystis carinii pneumonia in patients being registered for smear-negative pulmonary tuberculosis in Malawi

The National TB Control Programme of Malawi registers and treats large numbers of patients with chronic cough for smear-negative pulmonary tuberculosis (PTB). Smear-negative PTB is diagnosed according to clinical and radiographic criteria, as mycobacterial cultures are not routinely available. In an area of high HIV seroprevalence there is a concern that other opportunistic infections apart from TB, such as Pneumocystis carinii, may be missed owing to lack of diagnostic facilities. The aims of this study were to investigate (i) the extent of P. carinii pneumonia (PCP) in patients about to be registered for smear-negative PTB; (ii) whether there were any clinical or radiological features that could help identify PCP in the absence of more detailed investigations; and (iii) the treatment outcome of PCP patients. A cohort of 352 patients who were about to be started on treatment for smear-negative PTB were investigated further in 1997-99 by clinical assessment, HIV testing and bronchoscopy. HIV sero-prevalence was 89% (278/313). A total of 186 patients underwent bronchoscopy and bronchoalveolar lavage, and PCP was diagnosed by indirect immunofluorescence or polymerase chain reaction in 17 (9%) of this subgroup. Dyspnoea was significantly more common in PCP cases compared to non-PCP cases (RR 1.35; 95% CI 1.24-1.48; P = 0.008), but discrimination between the groups was difficult using clinical criteria alone. The outcome of PCP cases was poor despite management with high-dose co-trimoxazole and secondary co-trimoxazole prophylaxis, with a median survival of 4 months (25-75% range: 2-12 months).

Use of clinical judgement to guide administration of blood transfusions in Malawi

The aim of this study was to investigate whether clinicians in Malawi could use clinical judgement alone to administer blood transfusions in accordance with guidelines. Clinicians at a district hospital did not use the Lovibond Comparator haemoglobin results provided by their laboratory as they felt them to be unreliable, preferring instead to rely on their clinical judgement alone to guide transfusion practice. Their transfusion practice and the Lovibond haemoglobin results were monitored against the World Health Organization recommended haemiglobincyanide method for haemoglobin measurement without the clinicians having access to this result. The Lovibond Comparator method was shown to have a sensitivity of only 21% to detect trigger haemoglobin values for transfusion published in local guidelines. Without access to a useful haemoglobin result, clinicians gave 67% of transfusions in accordance with the haemoglobin trigger values in the guidelines. This study shows that clinical features alone can provide a reasonable guide about the need for transfusion, and that poor quality laboratory tests limit the effectiveness of transfusion guidelines.

Are intestinal helminths a risk factor for non-typhoidal Salmonella bacteraemia in adults in Africa who are seropositive for HIV? A case- control study

Abstract In Africa, invasive, non-typhoidal Salmonella (NTS) infections are a common but life-threatening complication in adults who are seropositive for HIV. The high prevalence of human infection with intestinal helminths which penetrate the gut could explain the greater importance of NTS bacteraemia in Africa compared with that in industrialized countries. If helminth infection is a major risk factor for NTS it would provide a locally relevant, public-health target. Intestinal helminth carriage in 57 HIV-positive patients with NTS bacteraemia (the cases) was compared with that in 162 HIV-positive controls who were similar to the cases in terms of age, sex, urban dwelling and socio-economic factors. The prevalence of helminth infection, 29% overall, was lower among the cases (18%) than among the controls (33%), giving a crude odds ratio of 0.40 [with a 95% confidence interval (CI) of 0.21-0.9] and an adjusted odds ratio (aOR) of 0.79 (CI=0.4-1.8). Five (9%) of the cases and 12 (7%) of the controls were infected with nematodes which penetrate the gut (Ascaris lumbricoides and/or Strongyloides stercoralis). The aOR for infection with these penetrating worms, corrected for age, sex, urban dwelling and phase of study, was 1.40 (CI=0.4-4.5). The present results do not exclude the possibility that helminths play a role in invasive NTS infections, but are not consistent with helminths being a sufficient risk factor in this population to be a public-health target. Anthelmintics are unlikely to have a major impact on preventing NTS bacteraemia in patients diagnosed HIV-positive in Africa.