The American Journal of Tropical Medicine and Hygiene - Volume 73, Issue 1, 2005

This report attempts to quantify the economic losses due to Echinococcus multilocularis and E. granulosus in Shiqu County, Sichuan, People’s Republic of China, as well as illustrate the cost effectiveness of dog anthelmintic prophylaxis combined with a sheep and goat vaccination program in terms of disability-adjusted life years (DALYs) saved. We evaluated human losses associated with treatment costs and loss of income due to morbidity and mortality, in addition to production losses in livestock due to E. granulosus infection. Annual combined human and animal losses (95% confidence interval) is estimated to reach U.S.$218,676 (U.S.$189,850–247,871) if only liver-related losses in sheep, goats, and yaks are taken into account. This equates to approximately U.S.$3.47 per person annually or 1.4% of per capita gross domestic product. However, total annual losses can be nearly U.S.$1,000,000 if additional livestock production losses are assumed. Eventual prevention of 65–95% of annual losses due to cystic echinococcosis is suggested with proposed biannual dog anthelmintic prophylaxis and a sheep and goat vaccination program. Prevention of 9–50% of human alveolar echinococcosis-associated losses is suggested based on stochastic models for the current epidemiologic situation. The median estimated cost of the program would be approximately $56,000 per year, which is a fraction of the estimated combined livestock and human financial losses due to the disease. Overall cost for the proposed control program is within the World Health Organization second most cost-effective band of less than U.S.$150 per DALY averted. However, cost per DALY averted would be less than U.S.$25 dollars for the human health sector if cost sharing was implemented between the public health and agricultural sectors based on proportional benefit from control.

Everglades virus (EVEV), an alphavirus in the Venezuelan equine encephalitis (VEE) complex, is a mosquito-borne human pathogen endemic to South Florida. Field isolations of EVEV from Culex (Melanoconion) cedecei and laboratory susceptibility experiments established this species as its primary vector. However, isolates of EVEV from Ochlerotatus taeniorhynchus and Culex nigripalpus, more abundant and widespread species in South Florida, suggested that they also transmit EVEV and could infect many people. We performed susceptibility experiments with F1 generation Oc. taeniorhynchus and Cx. nigripalpus to evaluate their permissiveness to EVEV infection. In contrast to the high degree of susceptibility of Cx. (Mel.) cedecei, Oc. taeniorhynchus and Cx. nigripalpus were relatively refractory to oral EVEV infection, indicating that they are probably not important vectors. Identification of vectors involved in enzootic EVEV transmission will assist in understanding potential changes in vector use that could accompany the emergence of epizootic or epidemic EVEV.

A case-control study was conducted to examine the relationship between severe acute respiratory syndrome (SARS) and the time-dependent precautionary behaviors taken during an outbreak of SARS in Hanoi French Hospital (HFH), Vietnam. Masks (odds ratio [OR] = 0.3; 95% confidence interval [CI]: 0.1, 0.7) and gowns (OR = 0.2; 95% CI: 0.0, 0.8) appeared to prevent SARS transmission. The proportion of doctors and nurses who undertook each measure significantly improved (χ2 = 9.8551, P = 0.043) after the onset of secondary cases. The impact of individual behaviors on an outbreak was investigated through mathematical approaches. The reproduction number decreased from 4.1 to 0.7 after notification. The basic reproduction number was estimated, and the use of masks alone was shown to be insufficient in containing an epidemic. Intuitive results obtained by means of stochastic individual-based simulations showed that rapid improvements in behavior and isolation would increase the probability of extinction.

As infants lose maternally derived antibody, they experience a period when antibody levels are insufficient to protect against measles yet may interfere with immunization. In Kangaba Mali, sera were collected from 89 2–8-month-old infants and 32 9–10-month-old infants without a history of measles or vaccination; post-vaccination sera were collected from 24 of the 9–10-month-old infants 3–5 weeks after receiving measles vaccine. Measles antibody was measured by plaque reduction neutralization (PRN) and enzyme linked immunosorbent assay. At two months of age, 30% had protective PRN titers; among six-month-old infants, none had protective titers. Prior to vaccination, 16% of 9–10-month-old infants exhibited protective titers; all demonstrated protective titers post-vaccination. The early onset of the window of vulnerability in Kangaba infants likely reflects the changing ecology of measles in Africa. Ways to protect these vulnerable infants against measles must be devised.

Determining the dose of an arbovirus transmitted by a mosquito is important to design transmission and pathogenesis studies simulating natural infection. Several different artificial infection and transmission methods used to assess vector competence and to estimate the dose injected during mosquito feeding have not been fully evaluated to determine whether they accurately reflect natural transmission. Additionally, it is not known whether different mosquito vectors transmit similar amounts of a given virus. Therefore, we compared three traditional artificial transmission methods using Venezuelan equine encephalitis virus (VEEV) and Aedes albopictus and Ochlerotatus taeniorhynchus mosquitoes. Both the mosquito species and the infection route used affected the amount of virus detected in the saliva after a 10-day extrinsic incubation period. Median titers of virus detected in saliva of Ae. albopictus and Oc. taeniorhynchus mosquitoes ranged from 0.2 to 1.1 log10 (mean 0.7–1.4 log10) and 0.2 to 3.2 log10 (mean 1.0–3.6 log10) plaque-forming units, respectively. The results of this study will aid in the design of transmission and pathogenesis studies involving arboviruses.

Hepatitis A virus (HAV) has different epidemiologic and clinical patterns, depending on the level of endemicity in a given geographic area. Tunisia is considered a region of high endemicity for hepatitis. Improvement of socioeconomic conditions in this country has made a determination of the seroprevalence of this disease advisable. We assessed the seroprevalence of HAV in Sousse in central Tunisia. A total of 2,400 school children 5–20 years of age (mean ± SD age = 11.7 ± 3.5 years) were selected by two-stage cluster sampling and tested serologically for IgG antibody to HAV by using an enzyme-linked immunosorbent assay. The overall seroprevalence among this population was 60% (44%, in children < 10 years old, 58% in those 10–15 years of age, and 83% in those > 15 years of age. Seroprevalence also varied according to area of residence. At the age of 10, 21.3% of school children living in the urban areas and 87.7% of those living in rural areas had antibodies to HAV. Other factors that increased seroprevalence included non-potable water, crowding, and a low education level of parents with odds ratios of 4.37, 2.96, and 2.62, respectively. This study has shown an increase of seroprevalence with age, suggesting that transmission among younger children has decreased, particularly in urban areas. Programs to prevent hepatitis A may need to be modified based upon the changing age distribution of the disease and mass vaccination program could be indicated if additional incidence and prevalence data confirm the intermediate endemicity of HAV.

Sporadic cases of cell-mediated immunity (CMI) in persons exposed to hepatitis C (HCV) but evidently uninfected have been reported. To further define this, we measured CMI in individuals without evidence of HCV infection, that is, negative for HCV-antibodies (anti-HCV) and RNA, residing in a rural Egyptian community where prevalence of anti-HCV was 24%. Cell-mediated immunity (CMI) measured by interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay, confirmed by intracellular staining using flow cytometry, against HCV peptides was measured in seronegative individuals with high-risk (HR) and low-risk (LR) exposures to HCV. Thirteen of 71 (18.3%) HR subjects but only 1 of 35 (2.9%) LR subjects had detectable CMI (P = 0.032). These data are compatible with the hypothesis that exposures to HCV may lead to development of HCV-specific CMI without anti-HCV and ongoing viral replication. We speculate induced CMI clears HCV sometimes when anti-HCV is not detectable, and HCV-specific CMI is a useful surrogate marker for exposure to HCV.

Sexually transmitted infections are a serious health problem in Honduras. Human papillomavirus (HPV) and Chlamydia trachomatis are major causes of sexually transmitted diseases. To determine the prevalence of C. trachomatis and HPV in young women, 100 female university students in Honduras were assayed for the presence of these pathogens. Twenty-eight percent were positive for HPV and 6% were positive for C. trachomatis. These results show that genital HPV and C. trachomatis infections are very common among sexually active young women in Honduras. It is vital to promote extensive public awareness campaigns among sexually active women concerning preventive measures of these diseases.

A cross-sectional study was undertaken to determine the prevalence of cryptosporidiosis and its clinical and laboratory pattern in Venezuelan HIV-infected patients (N = 397). At enrollment, they underwent thorough clinical history and physical examination and provided stool specimens for the identification of Cryptosporidium sp. and other parasites. Cryptosporidium sp. was identified in 59 subjects (15%). This infection was strongly associated with acute and chronic diarrhea, weight loss, CD4+ counts below 100 cells/mm3, older age in patients with leukopenia, and more than 5 stools per day when CD4+ counts were below 100 cells/mm3. In addition, patients with Cryptosporidium infection were less likely to be coinfected with Isospora belli (OR = 0.05, P = 0.001). In fact, results of the current study confirm the worldwide importance of cryptosporidiosis as a clinically significant opportunistic infection associated with an advanced stage of immunosuppression.

Understanding the total lymphocyte count (TLC)-CD4 count relationship could aide design predictive instruments for making clinical decisions during antiretroviral therapy, especially in underserved resource-poor settings. We performed multiple regression analyses to assess the prediction of CD4 count using TLC on 771 participants with 4,836 visits. In linear and logistic regression TLC, hemoglobin, gender, history of AIDS, and weight predicted CD4 count and CD4 < 200, respectively, before and after highly active antiretroviral therapy (HAART) use. On HAART, the adjusted odds ratios (OR) for TLC < 1500 (optimal TLC cutoff) were 5.1 (95%CI 4.0, 6.5; P < 0.001), and off HAART, 4.6 (95%CI 3.4, 6.2: P < 0.001) with high predictive power. TLC predicts CD4 count and CD4 < 200 cells/μL well during HAART. Including the additional factors improves performance. TLC is simple and inexpensive and can be used in many ways to develop clinical decision-making tools in underserved resource-poor settings during HAART therapy.

The Women’s Health Study of Accra is a cross-sectional study designed to measure the burden of communicable and noncommunicable diseases in adult women residing in Accra, Ghana. This study assessed the prevalence rate of HIV and risk factors associated with HIV infection in 1,328 women age 18 years and older. The weighted overall HIV prevalence rate for women residing in Accra is 3.1%. The highest prevalence rate of HIV infections was identified in women age 25 to 29 years at 8.3%, OR (95%CI) 3.8 (1.68–8.33), P = 001. In addition to young age, other significant risk factors included sexually transmitted infection (STI) symptoms (OR 1.81 [1.14–2.87], P = 0.012) and mean number of lifetime sexual partners (P < 0.001). All HIV-positive women were sexually active. Other findings significantly associated with HIV-positive status included chills, oral lesions, tuberculosis, bloody sputum production, and intestinal parasite infections. There was a significant association with HIV-positive status and locality of residence in the city. There was no association with reported use of condoms, blood transfusions, surgery, reproductive health history including pregnancy or number of sexual partners, symptoms suggestive of AIDS, or self-perception of health. There was also no association with education level, religion, ethnicity, marital status, or socioeconomic level. This community-based study confirms the need to target young, sexually active women for HIV educational and preventive initiatives. A strong Ghanaian public health initiative to increase awareness of the risks of HIV and the link to STIs is critical at this time to prevent the further increase in HIV prevalence and the resultant HIV-associated illnesses.

We report a case of acute, self-resolving leptospirosis presenting in a HIV-positive patient from the Peruvian Amazon. The patient presented with an undifferentiated acute febrile illness that resolved without treatment, diagnosed retrospectively as leptospirosis by serology and real-time polymerase chain reaction. Five months later, he was admitted because of a febrile illness with jaundice, hepatosplenomegaly, peripheral edema, and oral candidiasis. Because of the clinical suspicion of AIDS, stored sera of the previous admission were tested, and HIV seropositivity was confirmed, proving that the condition was present at the first admission. Acute leptospirosis in HIV coinfection is not inevitably severe, and there is probably a wide variation in clinical manifestations similar to what occurs in immuno-competent hosts.

To evaluate whether familial clustering occurs in mucosal leishmaniasis (ML), patients with ML (index cases) were randomly selected from medical records at a health post in an endemic area for Leishmania braziliensis infection. Control individuals (index controls) matched by age, gender, and place of residence to index cases were selected. Family members of index cases and controls were compared with respect to environmental factors and the incidence of cutaneous leishmaniasis (CL) and ML. Delayed type hypersensitivity test (DTH) to Leishmania antigen was tested in selected families. Among 289 members of 46 families enrolled, significant differences were found in the frequencies of CL (37% versus 20%) and ML (5% versus 0) in case versus control families, respectively. Families with 2 cases of ML had a higher frequency (29.6%) of DTH-positive individuals than control families (9.4%). These data demonstrate familial clustering of CL, ML, and positive DTH skin tests in an area endemic for L. braziliensis infection.

A case-control study was conducted to understand the risk factors associated with kala-azar in disease-endemic areas of Bihar, India. A total of 134 kala-azar cases treated at the Rajendra Memorial Research Institute of Medical Sciences in Patna and 406 healthy controls selected randomly from the neighborhoods of cases in their native villages were included in the study. Univariate analysis showed that education, a history of other diseases in the previous year, a history of kala-azar in the family, type of walls in houses, presence of a granary inside houses, presence of vegetation around houses, bamboo trees near houses, and irregular spraying around houses with DDT were risk factors. Multivariate analysis showed that a history of other diseases in the previous year (odds ratio [OR] = 3.6, P = 0.002), a history of kala-azar in the family (OR = 1.8, P = 0.03), mud-plastered walls in houses, (OR = 2.4, P = 0.0001], a granary inside houses (OR = 4.3, P = 0.0001), presence of bamboo trees around houses (OR = 2.3, P = 0.001), and houses not sprayed with DDT in the past six months (OR = 3.4, P = 0.0001) were significant risk factors for kala-azar. These results will be useful in developing kala-azar control programs for identifying intervention strategies such as better housing, regular and proper insecticide spraying, and promoting health awareness to the community residing in disease-endemic areas for reducing transmission and incidence of this disease.

Therapeutic failure in the treatment of cutaneous leishmaniasis (CL) occurs in 5% of patients infected by Leishmania braziliensis. This study evaluates the use of topically applied granulocyte macrophage colony-stimulating factor (GM-CSF) combined with the standard dose of antimony to treat refractory cases of CL. Five patients who had received three courses or more of antimony were enrolled in an open-label clinical trial. One to 2 mL of the GM-CSF solution (10 μg/mL in 0.9% saline) was reapplied topically, and dressings were changed three times per week for 3 weeks, associated with standard parenteral antimony (20 mg kg−1 day−1 for 20 days). All the patients healed their CL ulcers; 3 healed within 50 days (21, 27, and 44 days) and 2 in 118 and 120 days after beginning therapy. There were no side effects. This study shows that combined topically applied GM-CSF and antimony can be effective and well tolerated in the treatment of relapsed CL.

The sensitivity and specificity of lymph node and bone marrow smear microscopy for the diagnosis of Leishmania infantum–infected dogs was evaluated in 79 dogs with leishmaniasis (Group A), 52 asymptomatically infected dogs (Group B), and 44 healthy noninfected dogs (Group C). Light microscopy examination included 10 to 1,000 oil immersion fields, and the density of Leishmania amastigotes was scored by a 0 to +6 scale. Using polymerase chain reaction as the gold standard, the specificity of lymph node and bone marrow cytology was 100%, whereas sensitivity ranged from 7.8% to 92.6%, being significantly higher in Group A compared with Group B. The amastigote scores were also significantly higher in Group A compared with Group B. These results indicate that lymph node and bone marrow cytology is a highly sensitive and specific method for the diagnosis of canine patent leishmaniasis, whereas its sensitivity is relatively low in asymptomatic infections.

The frequency of Entamoeba histolytica and Entamoeba dispar infection was analyzed in a rural community in the state of Morelos, Mexico, using polymerase chain reaction (PCR). Sociodemographic variables as risk factors for the infection were assessed. Results highlighted the number of individuals with intestinal parasites (43.1%) in the community, indicating extensive fecalism. A high frequency of E. histolytica asymptomatic infection, higher than E. dispar infection (13.8% versus 9.6%), was detected by PCR. Anti-amebic antibody levels (IgG) in serum and saliva (IgA) samples were not associated with E. histolytica intestinal infection. These findings suggest a predominant distribution of E. histolytica strains of low invasive potential in this community.

We report the case of a 29-year-old Jamaican patient who presented with severe pain, redness, and swelling of both eyes. She was a regular soft contact lens wearer who did not maintain standard lens care. She was treated for a possible microbial/viral keratitis using topical ciprofloxacin drops, topical acyclovir ointment, and topical atropine drops. The response was inadequate, and scrapings from her cornea, contact lens cases, and both lenses revealed Acanthamoeba on microscopy, which was shown to be Acanthamoeba polyphaga using polymerase chain reaction. She was treated using chlorhexidine 0.02% hourly, ciprofloxacin every 4 hours, and atropine 1% every 12 hours, along with oral ketoconazole 200 mg twice daily with a dramatic response. However, she subsequently suffered slow corneal epithelial regrowth with severe scarring, vascularization, and cortical lens opacification and was referred for penetrating keratoplasty and cataract surgery. This is the first case of severe keratitis caused by Acanthamoeba to be reported from Jamaica and demonstrates that this emerging pathogen can be a cause of severe keratitis in the tropics.