During an epidemic of Plasmodium falciparum malaria in Chogoria, Kenya, P. falciparum DNA was collected from 24 cases of severe malaria admitted to hospital for parenteral quinine treatment. These patients had all failed first- (chloroquine) and second-line (sulfadoxine-pyrimethamine or amodiaquine) drug treatments. Twenty-two (92%) of the 24 patients sampled carried parasites with the (Asn)86(Tyr) point mutation in the pfmdr1 gene (chromosome 5), 20 (83%) had an (Asp)1246(Tyr) mutation and 18 (82%) had both of these mutations. These alleles are both reported to be associated with chloroquine-resistance. Polymorphisms in the cg2 gene (chromosome 7) are also associated with chloroquine resistance, and 18 (75%) of the 24 parasite samples each had the cg2 and pfmdr1 polymorphisms. These 18 samples also had the mutations associated with resistance to pyrimethamine and sulfadoxine: (Asn)51(Ile), (Cys)59(Arg) and (Ser)108(Asn) of gene dhfr (chromosome 4) and (Ala)437(Gly) and (Lys)540(Glu) of dhps (chromosome 8), respectively. Genotyping of the parasites from all 24 patients revealed extensive diversity in the sequences for the merozoite surface antigens (MSA-1 and MSA-2) and the glutamate-rich protein (GLURP) and indicated that each sample contained more than one parasite clone. Although samples from non-admitted malaria cases were not available, it appears that drug resistance may have played an important role in the development of severe malaria in this epidemic.

An animal model of Legionella pneumophila pneumonia was developed to study aerosol infection, pathogenesis, and pulmonary host defense mechanisms. Guinea pigs were exposed in an inhalation facility that limited the aerosol of L pneumophila to the snout. Bronchoalveolar lavage was used to sample airspace cells, secretions, and bacteria during developing infection in 79 exposed animals and 13 uninfected controls. An influx of polymorphonuclear neutrophils followed exponential bacterial growth during the initial three days of infection and coincided with limitation of the increase in bacteria recovered. A macrophage influx occurred at three to five days. Bacteria were eliminated from the lung by 11 days after exposure. Albumin in lavage fluid peaked at two days. Most viable L pneumophila organisms were associated with alveolar macrophages, whereas most of the bacteria associated with polymorphonuclear neutrophils were nonviable. Recruited, and possibly immune, defenses appear to be required for successful resolution of legionella pneumonia.

Of nine patients with Legionnaires' disease, seven were receiving corticosteroids, and all nine had serious underlying diseases. Direct immunofluorescent examination of respiratory secretions, including sputum and transtracheal aspirates, showed the Legionnaires' disease (LD) bacterium in five of seven patients who seroconverted and in a sixth patient with a single elevated titer to the LD bacterium. All nine patients received erythromycin therapy, and five survived. Two patients showed persistence of their infection after receiving 2 weeks of erythromycin therapy, and two patients developed pulmonary abscesses. These cases of Legionnaires' disease show the occurrence of pulmonary abscesses, the possibility of relapse after giving only 2 weeks of erythromycin therapy, and the utility of direct immunofluorescence for early diagnosis.

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The efficacy of 10-microg and 40-microg hepatitis B vaccines was compared with that of an investigational vaccine containing pre-S1, pre-S2, and S subunit particles (mixed particle vaccine) in inducing protective anti-hepatitis B surface antigen (anti-HBs) concentrations in 46 otherwise healthy persons who previously did not develop measurable levels of antibodies to at least one complete course of vaccine. A statistically significant difference was seen in the percentage of subjects who developed protective levels of anti-HBs (> or = 10 mIU/mL) with three 40-microg doses of S subunit vaccine versus the other groups. One hundred percent of the 40-microg dose group developed protective anti-HBs titers. No difference in adverse effects was noted.