Leptospirosis mimicking acute cholecystitis among athletes participating in a triathlon.

Leptospirosis, a disease acquired by exposure to contaminated water, is characterized by fever accompanied by various symptoms, including abdominal pain. An acute febrile illness occurred in athletes who participated in an Illinois triathlon in which the swimming event took place in a freshwater lake. Of 876 athletes, 120 sought medical care and 22 were hospitalized. Two of the athletes had their gallbladders removed because of abdominal pain and clinical suspicion of acute cholecystitis. We applied an immunohistochemical test for leptospirosis to these gallbladders and demonstrated bacterial antigens staining (granular and filamentous patterns) around blood vessels of the serosa and muscle layer. Rare intact bacteria were seen in 1 case. These results show that leptospirosis can mimic the clinical symptoms of acute cholecystitis. If a cholecystectomy is performed in febrile patients with suspicious environmental or animal exposure, pathologic studies for leptospirosis on formalin-fixed, paraffin-embedded tissues may be of great value.

Genetic diversity among Lassa virus strains.

The arenavirus Lassa virus causes Lassa fever, a viral hemorrhagic fever that is endemic in the countries of Nigeria, Sierra Leone, Liberia, and Guinea and perhaps elsewhere in West Africa. To determine the degree of genetic diversity among Lassa virus strains, partial nucleoprotein (NP) gene sequences were obtained from 54 strains and analyzed. Phylogenetic analyses showed that Lassa viruses comprise four lineages, three of which are found in Nigeria and the fourth in Guinea, Liberia, and Sierra Leone. Overall strain variation in the partial NP gene sequence was found to be as high as 27% at the nucleotide level and 15% at the amino acid level. Genetic distance among Lassa strains was found to correlate with geographic distance rather than time, and no evidence of a "molecular clock" was found. A method for amplifying and cloning full-length arenavirus S RNAs was developed and used to obtain the complete NP and glycoprotein gene (GP1 and GP2) sequences for two representative Nigerian strains of Lassa virus. Comparison of full-length gene sequences for four Lassa virus strains representing the four lineages showed that the NP gene (up to 23.8% nucleotide difference and 12.0% amino acid difference) is more variable than the glycoprotein genes. Although the evolutionary order of descent within Lassa virus strains was not completely resolved, the phylogenetic analyses of full-length NP, GP1, and GP2 gene sequences suggested that Nigerian strains of Lassa virus were ancestral to strains from Guinea, Liberia, and Sierra Leone. Compared to the New World arenaviruses, Lassa and the other Old World arenaviruses have either undergone a shorter period of diverisification or are evolving at a slower rate. This study represents the first large-scale examination of Lassa virus genetic variation.

Analysis of the 1998 outbreak of leptospirosis in Missouri in humans exposed to infected swine.

OBJECTIVE: To determine the extent of leptospirosis in persons exposed to infected swine, confirm the source of disease, define risk factors for infection, and identify means for preventing additional infections during an outbreak in Missouri in 1998. DESIGN: Cross-sectional study. SAMPLE POPULATION: 240 people and 1,700 pigs. PROCEDURE: An epidemiologic investigation was conducted of people exposed to infected pigs from the University of Missouri-Columbia swine herd. The investigation included review of health of the pigs, a cross-sectional study of the people handling the pigs, serologic testing of human and porcine sera, and risk-factor analysis for leptospirosis within the human population. RESULTS: Serologic testing of samples collected at the time of the investigation indicated that 59% of the pigs had titers to leptospires, denoting exposure. Of the 240 people in the exposed study population, 163 (68%) were interviewed, and of these, 110 (67%) submitted a blood sample. Nine (8%) cases of leptospirosis were confirmed by serologic testing. Risk factors associated with leptospirosis included smoking (odds ratio [OR], 14.4; 95% confidence interval [CI], 1.39 to 137.74) and drinking beverages (OR, 5.1; 95% CI, 1.04 to 24.30) while working with infected pigs. Washing hands after work was protective (OR, 0.2; 95% CI, 0.03 to 0.81). CONCLUSIONS AND CLINICAL RELEVANCE: Leptospirosis is a risk for swine producers and slaughterhouse workers, and may be prevented through appropriate hygiene, sanitation, and animal husbandry. It is essential to educate people working with animals or animal tissues about measures for reducing the risk of exposure to zoonotic pathogens.

A survey for antibodies to Lassa virus among health workers in Nigeria.

A study was conducted among 552 health workers at 6 health facilities in Nigeria. Lassa virus immunoglobulin (Ig) G antibody was detected in 12.3%, using an enzyme-linked immunosorbent assay. Antibody prevalence in the 6 health centres ranged from 1.2% to 27.3%. Prevalences were higher in primary and secondary health facilities than in tertiary centres. Seroprevalences ranged from 1.7% to 23.7% among different occupational groups of health workers; the highest observed antibody prevalence was among ward aids. Lassa virus IgM antibody, indicating recent infection, was present in 6 of the health workers, 5 of whom were ward aids and one was a nurse. All of the health workers with specific IgM came from a single facility in Lafia, sampled during an outbreak of Lassa fever.

Hepatitis B virus infection among blood donors and pregnant women in Maiduguri, Nigeria.

Hepatitis due to hepatitis B virus (HBV), and sequelae such as hepatocellular carcinoma (HCC) are very common in the Maiduguri area of Nigeria. In a serological survey of 287 blood donors (all males) and 224 pregnant women, we found that 22.0% of the blood donors and 11.6% of the pregnant women were positive of HBsAg. For HBeAg the prevalence rates were 6.64% and 1.39% respectively. These findings make it imperative that all blood donations and pregnant women be screened for HBsAg. All positive blood units should be discarded and all children born to positive women be vaccinated against hepatitis B, preferably during the first year of life. In addition, a more extensive programme against hepatitis B needs to be undertaken. It is suggested that HBV vaccination be included in the expanded programme of immunization, so that all children, irrespective of the serological status of their mothers, will be vaccinated against hepatitis B.

Increasing risk of transfusion-associated AIDS as the pandemic spreads: experience in Maiduguri, Nigeria.

Complacency and financial considerations have led many hospitals in developing countries with low HIV antibody prevalence to disregard the importance of pre-screening for HIV antibodies blood meant for transfusion. This report shows that during the year 1987 in which mandatory screening of donated blood was introduced at the University of Maiduguri Teaching Hospital, HIV antibody prevalence in donated blood units was 0%. However, four years later the prevalence had risen to 2.76%. This observation underlines the increasing risk to which transfusion recipients are exposed if given unscreened blood as HIV spreads with time. This spread can be rapid.

PIP: Based on screening of all blood units donated to a Nigerian hospital using enzyme linked immunosorbent assay (ELISA) and Western blot, the prevalence of human immunodeficiency virus (HIV) rose from 0% in 1987 to 2.76% in 1991 (Western blot positives only). The prevalence in intervening years was .33% in 1988, .38% in 1989, and .94% in 1990. Western blot indeterminates rose from 0% in 1987 to 2.05% in 1991. The percentage of blood units which were ELISA positive but Western blot negative plus ELISA borderline rose from .90% in 1987 to 2.87% in 1991. Overall, the percentage of donated units that had to be discarded, because of a positive or borderline ELISA, rose from .90% in 1987 to 7.67% in 1991. Donors were male residents of Maiduguri, Nigeria, between the ages of 18 and 55. Positive units were from donors between the ages of 22 and 45 who did not belong to any high risk groups. All positives were for HIV-1 only. In view of these findings, screening of blood donations, although expensive, is recommended, even in areas such as Nigeria where the overall prevalence of HIV is low. Because of expense, pooling of sera for testing may be necessary and transfusions should be limited to imperative situations only. Also, fees can be charged for screening.