Immunohistological and electron microscopic studies of microfilariae in skin and lymph nodes from onchocerciasis patients after ivermectin treatment.

Microfilariae were studied in skin and lymph node biopsies from Liberian patients with generalised onchocerciasis 12-78 hours after administration of a single dose of 150 micrograms/kg body weight using histology, transmission electron microscopy and immunocytological staining with antibodies against an immunodominant antigen of Onchocerca volvulus. Most microfilariae in the skin appeared morphologically intact and beginning signs of degeneration were seen only on the ultrastructural level. The densities of microfilariae in the lymph nodes were about thousandfold higher in ivermectin treated patients. More than 90% of the microfilariae in the lymph nodes showed distinct signs of degeneration. Early changes were seen in the muscle cells. The disintegrating microfilariae in the lymph nodes were always encircled by eosinophils or macrophages or both cells. Immunohistological staining with antifilarial antibodies increased the detection of small and disintegrating pieces of microfilariae considerably.

Pediatric Lassa fever: a review of 33 Liberian cases.

Thirty-three cases of pediatric Lassa fever were identified at Curran Lutheran Hospital and Phebe Hospital in Liberia between January 1980 and March 1984. All 18 fetal cases died and the case-fatality rate for 15 childhood cases was 27%. We identified four clinical presentations according to age, including a case of congenital Lassa fever, a condition not reported previously. Two cases of Lassa fever were found serologically during a one-month survey of all pediatric admissions at Curran Lutheran Hospital, 2.4% of those children who had serum pairs collected. We also identified a "swollen baby syndrome" consisting of widespread edema, abdominal distention, and bleeding. This distinctive clinical presentation of Lassa fever ended in death in three of four cases and was present in three of the four childhood deaths in this series. Its absence seems to be a good prognostic indicator in children.

An outbreak of antibiotic-resistant Salmonella enteritidis in Liberia, West Africa.

Between October 1980 and August 1982, 100 patients in the pediatric population at Curran Lutheran Hospital, Zorzor, Liberia were identified as having multiple drug-resistant Salmonella enteritidis serotype enteritidis. The illness usually presented as an enteric fever but also as meningitis, gastroenteritis, empyema, subcutaneous abscesses, chronic otitis media, or a combination of these conditions. Predisposing factors were young age and debilitation from malnutrition or measles. The mortality of infected patients was 27.8%. The organism was originally misidentified as a Citrobacter species because of a delayed reaction on lysine decarboxylase medium. Incubation of the medium for five days resulted in a positive reaction that identified the organism as a Salmonella species. The isolates were resistant to multiple antibiotics. Genes mediating resistance were located on a 120-megadalton conjugative plasmid. A cryptic nonconjugative 40-megadalton plasmid was also present in several isolates.

Practical management of rabies and the 1982 outbreak in Zorzor District, Liberia.

A rabies outbreak in Zorzor District, Liberia, in 1982 resulted in 31 known bitten and 12 known exposed patients. Human diploid cell strain (HDCS) vaccine was used to vaccinate 40 patients. Of these, 34 were vaccinated at Curran Lutheran Hospital, Zorzor, Liberia, mostly by the intradermal (i.d.) route. Five of 28 bitten patients who started their vaccinations did not complete the 4-dose course, including a 16-year-old boy who did not return after the first injection and later died of rabies. There were also 2 deaths in 3 known bitten but unvaccinated patients. None of the 23 bitten who received 4 doses of HDCS vaccine contracted rabies. The i.d. route was also used for pre-exposure prophylaxis. This method of vaccination is less expensive than the intramuscular route and in our clinical setting we would not have been able to vaccinate all the patients without using it. A practical approach to rabies vaccination in a developing country and the technique of intradermal vaccination are discussed.

Endemic Lassa fever in Liberia. III. Characterization of Lassa virus isolates.

Sixty-three virus isolates were obtained by inoculation of Vero cells with sera from 50 hospital in-patients in Liberia with acute febrile illnesses. 57 of the isolates were presumptively identified as Lassa virus (LV) by direct fluorescent antibody (DFA) staining of inoculated Vero cells. These, and six additional isolates obtained only by titration of supernatant fluids from inoculated Vero cells, were definitively identified as LV in a neutralization test. Two additional LV isolates were obtained from a patient's sera from Nigeria. By cross-neutralization tests, the Nigerian LV strains were serologically identical to the prototype Nigerian LV strain (PP) but were distinct from both a reference LV strain from Sierra Leone (SL), and from the Liberian (LIB) strains isolated in this study. The LIB and SL strains were closely related to each other, but not to the Nigerian LV strains. LIB LV strains were tested for virulence in strain 2 and 13 guinea-pigs, and a spectrum of virulence was observed which correlated only approximately with disease severity for human patients. Two human-lethal isolates killed all inoculated strain 2 and 13 guinea-pigs, whereas nine isolates from mildly ill patients were benign for guinea-pigs. Yet some LV isolates from severely ill or lethally infected patients, especially those from pregnant women and infants, were totally benign for guinea-pigs. These data suggest that antigenically distinct LV strains exist in nature, and that antigenically indistinguishable LV isolates may differ in virulence potential for various hosts.

Endemic Lassa fever in Liberia. IV. Selection of optimally effective plasma for treatment by passive immunization.

The efficacy of passive immunization for treatment of Lassa Fever (LF) is believed to depend on the titre of the neutralizing antibody infused. For the purpose of identifying optimal donors of LV-immune plasma, a population of LF-convalescent patients in Liberia was tested for prevalence of neutralizing antibody. Minimally protective titres, expressed as a log10 neutralization index, (LNI), were established in animal models as LNI greater than 2. LNI titres for 26 donors, tested eight or more months after illness, were modest: 16 titred 1 less than LNI less than 2, 4 titred 2 greater than LNI less than 3, and only 4 titred LNI greater than 3. Sequentially obtained plasma from six donors indicated that the LNI response was delayed relative to the indirect fluorescent antibody (IFA) response, that high titres (LNI greater than 3) occurred only after seven months and in only two of six patients. Most of the unselected LV-immune plasma will require concentration to therapeutically useful LNI titres. In a passive immunization experiment, guinea-pigs were protected by a late convalescent plasma (LNI = 4.8, IFA = 320) but not by an early plasma, (LNI = 0.6, IFA = 640), thus supporting the selection of immune plasma on the basis of the LNI. Cross serological testing with LV strains and convalescent plasma from patients in Sierra Leone, Liberia and Nigeria suggested that these LV strains were indistinguishable by cross-IFA, but were readily distinguishable by cross neutralization tests. Geographical matching of LV and plasma origins may thus be a factor in selection of optimal plasma for passive immunization of Lassa fever.

Mycobacterium ulcerans in Liberia: a clinicopathologic study of 6 patients with Buruli ulcer.

Two patients with Buruli ulcer (infection by Mycobacterium ulcerans) in the Foya region of Liberia have recently been reported. We describe three more patients which together with the two original patients establish the Mayor River basin as an endemic area of Buruli ulcer. We also describe a patient from the St. Paul River basin. This disease, unrecognized in Liberia before 1978, now seems to be widespread in Liberia and has been reported in neighboring Sierra Leone and observed in Ivory Coast as well. The possibility of Buruli ulcer appearing in other regions of West Africa should be anticipated. Diagnosis involves finding acid-fast bacilli in smears of the exudate from typical lesions or by finding in biopsy specimens the characteristic zone of coagulation necrosis containing acid-fast bacilli. The bacillus, Mycobacterium ulcerans, stains readily with the Ziehl-Neelsen (ZN) and Fite-Faraco (FF) procedures. Treatment is excision when the lesion is small and by debridement and grafting, combined with heat and chemotherapeutic agents when the lesion is large.

Endemic Lassa fever in Liberia. II. Serological and virological findings in hospital patients.

Patients admitted with fever to four Liberian hospitals were tested for Lassa fever (LF) by means of the indirect fluorescent antibody technique and by virus isolation. The incidence of LF and presumptive LF among consecutive febrile adult patients was 14% and 17% in two hospitals located in the interior; no cases of LF were found among 24 consecutive patients in a hospital near the coast. In the three inland hospitals the incidence of confirmed or presumptive LF among the patients in whom the diagnosis was seriously considered varied from 13% to 36%. Lassa virus was isolated from 17 patients out of the 59 cases found in this survey. LF is a common cause of fever in northern Liberia. The diagnosis depends upon the readiness of the staff to consider the diagnosis, the collection of blood specimens at appropriate times, and the preservation of sera at sub-freezing temperatures to permit survival of active virus and its subsequent recovery in an appropriate laboratory.

Endemic Lassa fever in Liberia. I. Clinical and epidemiological aspects at Curran Lutheran Hospital, Zorzor, Liberia.

In a study to assess the epidemiological and clinical aspects of endemic Lassa fever (LF) in Liberia at Curran Lutheran Hospital (CLH), 44 cases were diagnosed by virological and serological techniques over a 22-month period. During one calendar month, testing of febrile patients admitted to the medical-surgical ward revealed six cases of LF, 13% of all febrile cases and 17% of those who were tested. As the study progressed the diagnostic skills of the hospital staff improved. The most common mistake was the diagnosis of a case of LF as pneumonia; the most potentially serious diagnostic problem was differentiating LF from typhoid fever, a readily treatable infection. LF may also mimic other diseases such as aseptic meningitis, pelvic inflammatory disease, gastroenteritis or arbovirus infection. We found a previously unreported symptom of LF, rib tenderness typical of costochondritis. The mortality rate in the medical-surgical ward was 5.4%; the over-all case-fatality rate was 13.6%. Women outnumbered men by nearly three to one, and had a higher mortality particularly noted in the pregnant. LF is common at CLH, and as many as 100 cases may occur annually at this hospital.

Successful treatment with praziquantel of six patients infected with the African lung fluke, Paragonimus uterobilateralis.

Six cases of human paragonimiasis (Paragonimus uterobilateralis) are documented from Liberia and Guinea. These are the first cases reported from these countries. Paragonimiasis should be considered in the differential diagnosis of any West African patient who presents with hemoptysis. Praziquantel was used successfully to treat these patients, and may be the drug of choice for P. uterobilateralis infections.