Disease In Malawi Research Articles

Meningococcal disease in Malawi: studies on the genetic relatedness of the bacteria.

Seventy-seven meningococci, isolated from patients and carriers during a large epidemic of meningococcal meningitis in Malawi, were characterized in terms of antimicrobial susceptibility, plasmid content and multi-locus enzyme electrophoresis (MLEE). All the isolates were sensitive to chloramphenicol but six had high enough minimum inhibitory concentrations of penicillin (> or = 2 mg/litre) to render them clinically resistant. Only one isolate was sensitive to sulphonamides but all the isolates were sensitive to rifampicin and ciprofloxacin, two drugs that would be suitable alternatives in prophylaxis. None of the isolates carried plasmids. MLEE indicated that 32 (80%) of the cerebrospinal fluid isolates and 22 (69%) of those from carriers were closely related genetically (in two electropherotypes that differed at only one allele). The Malawian group A meningococci differed from three Ethiopian isolates by two or three alleles, indicating that direct spread from the sub-Saharan meningitis belt to Malawi was unlikely.

Helicobacter pyrlori in Malawi, Central Africa

A total of 160 adult Malawians with epigastric pain for longer than 2 weeks was investigated by endoscopy and serologically for evidence of infection with Helicobacter pylori. The organism was demonstrated histologically and/or by culture in 141 (88%) patients. With histological means and/or culture as the 'gold standard', the histological technique was 100% sensitive while culture was only 81% sensitive. All isolates tested were sensitive to amoxycillin and tetracycline; 74% were resistant to metronidazole. Endoscopic findings were normal in 104 (65%) patients (86.5% H. pylori positive). Evidence of duodenal ulcer was found in 41 (25%) patients (95% H. pylori positive). Histologically, gastritis was common, severe gastritis being associated with increased colonisation by H. pylori. Two kinds of urease test were found to be 100% specific for the presence of H. pylori. The sensitivity of the serological test (Helico-G test) was 98% but its specificity was only 27%. These results provide important background information for planned therapeutic studies in patients with upper gastro-intestinal disease in Malawi.

A current appraisal of banana and plantain diseases in Malawi

Abstract Major banana and plantain production centres in Malawi were surveyed for diseases and soil‐borne pests in June 1990. Fusarium wilt, which is also known as Panama disease (caused by Fusarlum oxysporum f. sp. cubense) caused considerable damage throughout the Karonga and Chitipa Districts of the Northern Region. The disease has been recognized in these areas since the early 1970s and probably was introduced into Malawi from southern Tanzania. The disease has eliminated the preferred banana cultivar, ‘Bluggoe’, in northern parts of the Karonga District, and at the time of the survey had begun damaging ‘Pisang awak’, the cultivar many producers have used to replace ‘Bluggoe’. Fusarium wilt was also found for the first time in the Thyolo and Mulanje Districts of the Southern region on ‘Bluggoe’. Black leaf streak (caused by Mycosphaerella fijiensis) was observed in the Nkhata Bay and Karonga Districts; it is reported for the first time in Malawi. The disease has been in the respective areas for 4 and ...

The status of Newcastle disease and the use of V4 vaccine in Malawi

Data on the incidence of Newcastle disease in Malawi obtained from various sources including serological surveys, questionnaires and interviews, as well as statistics on laboratory-confirmed cases, showed the disease to be widespread throughout the country. Chickens vaccinated with La Sota and Komarov vaccine strains were often inadequately protected against the disease, especially those under smallholder management. Trials involving laboratory chickens and chickens under both intensive and smallholder management showed that V4 vaccine, given by eye-drop, drinking water and oral droplet methods, induced an antibody response sufficient to protect birds against challenge with virulent field isolates of Newcastle disease virus. V4 is recommended as an alternative to La Sota and Komarov vaccines, particularly for smallholder flocks, because of its thermostability, its ease of administration and its transmissibility. Large scale use of V4 appears to have reduced the incidence of Newcastle disease in rural parts of Malawi.

Prevalence of pigeonpea diseases and associated crop losses in Asia, Africa and the Americas∗

Abstract Surveys were carried out to determine the prevalence of pigeonpea diseases in the major pigeonpea growing areas of Asia, Africa and the Americas between 1975 and 1980. In India, surveys in eleven states revealed that wilt, sterility mosaic, Phytophthora blight, Macrophomina stem canker and yellow mosaic were economically important diseases. Other diseases were of minor importance. Disease problems in Bangladesh, Malaysia and Nepal were of less importance. In Africa, wilt was a serious disease in Malawi (36.3%), Tanzania (20.4%) and Kenya (15.9%). Leaf spot in Kenya and Malawi, and powdery mildew in Kenya, Tanzania and Zambia were important. Other diseases were not economically important. In the Americas witches’ broom, Phoma stem canker and rust were the important diseases. Annual crop losses due to the combined effect of wilt and sterility mosaic diseases in India were estimated to be worth about US$ 113 millions. In Africa the estimated losses from wilt disease alone were over US$ 5 millions annually.

The epidemiology of fascioliasis in Malawi. Part II. Epidemiology in the definitive host.

The epidemiology of Fasciola gigantica Cobbold was studied in the definitive host and the epidemiological cycle was determined. The incidence of immature flukes was high in September to December and mature flukes from December to March. A survey of chronic fascioliasis was conducted covering almost the whole country. The prevalence of the disease was high in the Northern and Central Regions. Based on the epidemiological findings a control programme for the disease in Malawi was prepared.

IgM responses to hepatitis-A virus and hepatitis-B core antigen in acute and chronic liver disease in Malawi; possible role of non-A, non-B, hepatitis

Of 33 patients with acute hepatitis in Malawi, 21 had infection by hepatitis-B virus (HBV), five by hepatitis-A virus (HAV) and seven, who had no markers of current HBV or HAV infection, were probably infected by the agent(s) of non-A, non-B, hepatitis. 87 of 88 sera from persons without liver disease contained antibody to HAV and 49 antibody to hepatitis-B surface antigen (anti-HBs) (six were positive for hepatitis-B surface antigen). The diagnosis of recent infection by HAV was made by detecting HAV-specific IgM in single serum samples and, although such tests showed that HAV caused acute hepatitis, its absence in patients with chronic liver disease suggests that, unlike HBV, infection by HAV does not play a role in chronic liver disease in Malawi. Anti-hepatitis-B core antigen (anti-HBc)-specific IgM was detected in 19 of 21 patients with acute HBV infection, in three of five HBsAg-positive patients with cirrhosis, but in none of five HBsAg-positive patients with hepatoma.

Hepatitis-B virus determinants in patients with liver disease in Malawi

Sera from 185 patients admitted to hospital in Malawi with acute and chronic liver disease were tested for the following serological markers of hepatitis-B infection (HBV): hepatitis-B surface antigen (HBsAg) and its antibody (anti-HBs), HBe antigen (HBeAg) and its antibody (anti-HBe), and antibody to hepatitis-B core antigen (anti-HBc). Control groups consisted of patients without liver disease, students and blood donors. HBsAg was detected in 73%, 54·8% and 64% of patients with acute hepatitis, cirrhosis and hepatoma, respectively. 16% of patients with tropical splenomegaly syndrome (TSS) and 14·6% of patients with schistosomiasis, 9·5% of patients without liver disease, 1·4% of students and 7·6% of blood donors were HBsAg positive. Unexpectedly, 72·3% of HBsAg-positive specimens appeared to carry both major antigenic determinants ( ady). HBeAg was detected in 15·8% and anti-HBe in 13·1% of patients with acute HBsAg-associated hepatitis, these determinants being detected less frequently than in sera from patients with HBsAg-associated hepatitis in the UK. HBeAg or anti-HBe were rarely detected in patients with hepatoma. With the exception of students and blood donors, over 80% of the Malawian study population had markers of current or previous HBV infection in their sera. Anti-HBc occurred most frequently in patients with hepatitis, cirrhosis and hepatoma, their geometric mean titres (GMTs) being 67·6, 160·1 and 211, respectively. The GMTs of patients with TSS, schistosomiasis and non-hepatic disease were 2·0, 4·6 and 2·3, respectively.

Effects of groundnut sowing date and plant spacing on rosette virus disease in Malawi

AbstractIn a series of field trials at Chitedze, Malawi, groundnuts were sown at spacings of 30 cm, 7·5 cm and 2·5 cm within rows 90 cm apart. Contrasting sowing dates were approximately 1 December and 1 January. Immigration of alatae of Aphis craccivora Koch, monitored on observation plots, commenced 5–6 weeks after the emergence of early-sown groundnuts. Numbers of immigrant alatae were significantly greater on late-sown or open-spaced than on early-sown or close-spaced groundnuts, and were correlated with numbers of randomly distributed primary rosette virus infections. During observations, more alatae landed on 56–60-day-old plants than on 85–112-day-old plants. Similar numbers landed on 11–26-day-old plants at 30-cm and 2·5-cm spacing, but significantly more aphids settled on 30-cm spacing. The incubation period of rosette virus was consistently longer in 2·5-cm than in 30-cm spacing, and increased with plant age at inoculation. The virus was transmitted from a low proportion of infected plants before the appearance of rosette symptoms, and from a high proportion of plants snowing symptoms. The rate of spread of virus transmissions from inoculated sources within the crop varied significantly with spacing as 30 cm > 7·5 cm > 2·5 cm. Secondary spread of rosette varied, approximately, with the numbers of aphids per infected plant.

Incidence, development and symptoms of Cercospora disease of coffee in Malawi

The seasonal incidence, development and disease symptoms caused by Cercospora cojfeicola on leaves and berries of coffee (Coffea arabica) have been investigated. Disease spread is by wind-borne spores, which are relatively short lived. The fungus overwinters mainly as mycelium in lesions. Spores germinate over a wide range of temperature. Optimum temperature for growth in culture is 25 °C. The fungus penetrates the leaves through stomata, and the berries through wounds or sunscorch injury. The alternative host, Ricinus communis, is not important in maintaining the disease in Malawi.

Coffee bark diseases in Malawi: II. Properties of the causal organism and conditions favouring the disease

The conditions favouring spread of Fusarium stilboides and development of the diseases it causes have been investigated. Spread of the fungus is mainly by raindrop splash, but insects and pruning secateurs may also spread it. Entry is through wounds, pruning wounds providing the commonest port of entry. Spore germination occurs in a humid atmosphere without free water at an optimum temperature of 30 °C. Optimum temperature for growth in culture is 25°. Viability in infected bark is retained for 12 months, pathogenicity for 6 months. The fungus loses viability in field soil after only 1 month. Weed competition predisposes the plants to disease, but heavy mulching partly compensates for this.

Fungicidal Control of Plant Diseases in Malawi

Abstract Fungicidal spraying experiments carried out in a number of crops in Malawi are described. Bordeaux mixture (4 : 4 : 50) sprays applied after every 2 in. cumulative rainfall during the wet season to tomatoes gave the most economical control of late blight. Isariopsis griseola leafspot on beans was best controlled by Zineb applied weekly. Large groundnut yield increases follow fortnightly applications of copper and sulphur fungicides but these were uneconomical except on one variety. Worthwhile control of late blight on potatoes was achieved by shaking a cuprous oxide fungicide by hand from a hessian sack on to the crop four times during the growing season. Copper oxychloride applied at two-monthly intervals. to coffee controlled Cercospora coffeicola berry disease very cheaply.