Rapid identification of paragonimiasis foci by lay informants in Lao People's Democratic Republic

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species. Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex. Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 6.1).

Immunoblotting Identification of Diagnostic Antigens of Paragonimus westermani Type 1 for the Detection of Human Pulmonary Paragonimiasis in North East India

Human pulmonary paragonimiasis, an emerging concern in North East India, frequently masquerades as pulmonary tuberculosis due to clinical and radiological similarities, leading to diagnostic challenges. This research aimed to harness the immunoblotting technique to discern immunodiagnostic protein antigens from both adult worm and excretory-secretory (ES) extracts of the prevalent Paragonimus westermani type 1 in Arunachal Pradesh, North East India. We studied the time kinetics of immunoreactive patterns in relation to the duration of infection in rodent models. Immunoblot analyses were also conducted using sera from ELISA-positive patients confirmed with paragonimiasis, facilitating the selection of antigenic extracts with diagnostic potential. Further, ES protein antigens were subjected to 2D immunoblot analysis and immunoreactive protein spots identified using MALDI-TOF MS. The immunoreactivity patterns of ES antigens with sera of paragonimiasis-positive patients were detailed, and specific immunoreactive protein antigens were pinpointed using peptide mass fingerprinting (MALDI-TOF). This work underscores the enhanced diagnostic accuracy when combining ELISA with immunoblotting for pulmonary paragonimiasis in regions like North East India, marked by co-existing helminth infections.

Identification of suspected paragonimiasis-endemic foci using a questionnaire and detection of Paragonimus ova using the Ziehl-Neelsen technique in Zamboanga Region, the Philippines

Improving paragonimiasis surveillance, which is crucial for disease control, requires adopting new tools and techniques useful in mapping endemic areas. This study aimed to (1) develop a questionnaire to identify suspected paragonimiasis-endemic foci, (2) describe the epidemiology of paragonimiasis, and (3) evaluate Ziehl-Nielsen Staining technique (ZNS) in detecting Paragonimus ova. The questionnaire, which municipal health officers filled out, was based on proposed site inclusion criteria utilized in the integrated tuberculosis (TB)-paragonimiasis surveillance and control project. Newly deployed medical technologists in Zamboanga Region underwent training, which included laboratory diagnosis of paragonimiasis using preserved and fresh specimens and an integrated tuberculosis-paragonimiasis survey in nine selected barangays (villages). Paragonimiasis cases were found in seven out of the nine barangays identified by the questionnaire. Of the 373 patients, three (0.80%) were TB-positive, and 29 (7.77%) were paragonimiasis-positive. The highest paragonimiasis prevalence (27%) was found in Barangay Libato. Ziehl-Neelsen Staining technique (ZNS) correctly detected 8 out of the 29 samples positive (sensitivity - 27.59%; 95% CI: 12.73-47.24%) and all the 334 samples negative (specificity - 100%; 95% CI: 98.90-100%) for Paragonimus ova. The questionnaire may be improved by refining the inclusion criteria. In paragonimiasis-endemic areas, the ZNS and the NaOH concentration technique may be used for detecting Paragonimus ova. Modifying the ZNS, for instance by including a concentration step, may improve its sensitivity. The model for the integrated capacity building of health workers and surveillance and research demonstrated in this project may contribute to improving surveillance and control of paragonimiasis and other neglected tropical diseases.

Paragonimus and paragonimiasis in Asia: An update

Paragonimiasis, or lung fluke disease, is a typical food-borne parasitic zoonosis caused by infection with trematodes belonging to the genus Paragonimus. More than 50 species of Paragonimus have been reported throughout the world, of which seven valid species infect humans, an estimated one million people annually worldwide. Among the seven species, P. westermani, P. heterotremus, and P. skrjabini/P. s. miyazakii, distributed in Asia, are the most important species as the cause of paragonimiasis. Humans acquire infection through the ingestion of raw, pickled or undercooked freshwater crustaceans, 2nd intermediate hosts, or consuming raw meat of wild boar or deer, paratenic hosts. Infections often occur clustered in foci where dietary habits allow transmission of the parasites. Paragonimiasis typically causes a subacute to chronic inflammatory disease of the lungs. The symptoms, including chronic cough, chest pain, dyspnea and hemoptysis, mimic those of tuberculosis and lung cancer. Serologic tests are commonly used for the diagnosis of paragonimiasis, and Praziquantel is the treatment of choice. In this review, the current status of Paragonimus and paragonimiasis in Asia is outlined based on the latest information and findings. We also summarize current trends of paragonimiasis in Japan, which is one of the most endemic area of paragonimiasis in the world, for the better understanding and control of paragonimiasis.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

A tool for mass-screening of paragonimiasis: an enzyme-linked immunosorbent assay with urine samples

BACKGROUND

Paragonimiasis is one of the foodborn trematodiases and number of the patients was estimated to be about 23 million around the world. To obtain good compliance of people for the surveillance of paragonimiasis, an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of paragonimiasis with unconcentrated urine samples was developed.

RESULTS

Paragonimus westermani antigen specific IgG and IgG4 were detected in urine samples from paragonimiasis patients and the levels correlated well with those detected in the paired serum samples. Cross-reactions observed among other trematodiasis and a tuberculosis patient with the antigen specific IgG were much reduced by detecting the antigen specific IgG4; 9.2 % to 2.3 %.

CONCLUSIONS

The ELISA with urine samples, which are collected safely and easily, will be a useful tool for a mass-screening of paragonimiasis.

Intestinal Helminths Recovered from Humans in Xieng Khouang Province, Lao PDR with a Particular Note on Haplorchis pumilio Infection

A survey of intestinal helminths was undertaken in riparian people in Xieng Khouang Province, Lao PDR. Fecal specimens were collected from 643 people (289 males and 354 females) residing in 4 districts (Nonghet, Kham, Phoukout, and Pek) and were examined by the Kato-Katz technique. The overall helminth egg positive rate was 41.2%, and hookworms revealed the highest prevalence (32.7%) followed by Trichuris trichiura (7.3%) and Ascaris lumbricoides (5.6%). The positive rate for small trematode eggs (STE), which may include Opisthorchis viverrini, heterophyids, and lecithodendriids, was 4.4%. For recovery of adult helminths, 12 STE or nematode/cestode egg-positive people were treated with 40 mg/kg praziquantel and 15 mg/kg pyrantel pamoate, and then purged. Mixed infections with 2 Haplorchis species (H. pumilio and H. taichui), Centrocestus formosanus, Opisthorchis viverrini, a species of cestode (Taenia saginata), and several species of nematodes including hookworms and Enterobius vermicularis were detected. The worm load for trematodes was the highest for H. pumilio with an average of 283.5 specimens per infected person followed by C. formosanus, H. taichui, and O. viverrini. The worm load for nematodes was the highest for hookworms (21.5/infected case) followed by E. vermicularis (3.2/infected case). The results revealed that the surveyed areas of Xieng Khouang Province, Lao PDR are endemic areas of various species of intestinal helminths. The STE found in the surveyed population were verified to be those of heterophyids, particularly H. pumilio.

Integrated surveillance of pulmonary tuberculosis and paragonimiasis in Zamboanga del Norte, the Philippines

BACKGROUND

Pulmonary tuberculosis (PTB) and paragonimiasis remain as health problems in certain areas in the Philippines. Both share similar clinical manifestations, which include chronic productive cough, hemoptysis, dyspnea, fever, weight loss, and night sweats. This study aimed to determine the prevalence of PTB, paragonimiasis, and co-infections in Zamboanga del Norte, Philippines.

METHODS

This study was conducted in selected villages in two municipalities in Zamboanga del Norte. Patients with chronic cough were interviewed, examined, and requested to submit two sputum samples which were processed using Ziehl-Neelsen method to detect acid-fast bacilli (AFB), and NaOH concentration technique for the detection of Paragonimus ova.

RESULTS

A total of 836 patients submitted sputum samples for examination. Prevalence was 6·7% (2·5-12·7%) for paragonimiasis and 1·9% (0·9-6·3%) for PTB. Co-infection rate was 0·3%, with two identified cases. Positivity rates for males and females were 9·6 and 5·8% for paragonimiasis and 3·4 and 1·2% for PTB.

CONCLUSION

Pulmonary tuberculosis and paragonimiasis are co-endemic in Zamboanga del Norte, suggesting the need to integrate surveillance and control efforts. Strengthening local health systems through collaboration between different sectors is recommended for effective disease control. Development of more sensitive diagnostic tests is important for more accurate disease surveillance.

Paragonimiasis

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species (Table 5.1). Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex (Table 5.1). Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 5.1).

Active detection of tuberculosis and paragonimiasis in the remote areas in North-Eastern India using cough as a simple indicator

One of the essential steps in targeting tuberculosis (TB) intervention is early diagnosis and treatment of patients by reducing the reservoir of infection in the community. In the North-Eastern (NE) region of India pulmonary TB and paragonimiasis are overlapping public health issues. We performed a cross-sectional study in 63 remote villages from the two states Arunachal Pradesh (AP) and Assam to determine the prevalence of undiagnosed TB and paragonimiasis cases using cough as a simple indicator. In AP, 2961 individuals aged five years and above were examined and 1108 (37·4%) were found to have cough for one week or more. Of the 417 individuals who provided sputum, 11 (2·64%) were smear positive for acid-fast bacilli (AFB). All these cases were yet undiagnosed, thus the prevalence of new smear positive TB in AP was 0·37%. In Assam on the other hand 331 (23·5%) subjects out of 1410 individuals who were examined had a cough for one week or more and of the 112 individuals who provided sputum, 13 (11·6%) were smear positive for AFB. The prevalence of new smear positive TB cases was 0·78% in Assam. Sero-positivity of paragonimiasis in coughers of AP was 7·6% (n = 1091), which was significantly higher (p < 0·01) as compared to that in Assam (1·2%, n = 321). The findings of the present study suggest that TB remains a major public health concern in the NE region of India especially in the remote places and there is need to strengthen early case detection of TB.

No Paragonimus in high-risk groups in Côte d'Ivoire, but considerable prevalence of helminths and intestinal protozoon infections

BACKGROUND

Paragonimiasis is a neglected tropical disease caused by an infection with lung flukes that is transmitted through the consumption of undercooked crabs. The disease is often confused with tuberculosis. Paragonimiasis is thought to be endemic in south-western Côte d'Ivoire.

METHODS

Two cross-sectional surveys were carried out in the first half of 2009 in patients attending two tuberculosis centres of Abidjan. A third cross-sectional survey was conducted in May 2010 in children of two primary schools in Dabou, where crabs are frequently consumed. Patients with chronic cough provided three sputum samples plus one stool sample. Sputum samples were examined for tuberculosis with an auramine staining technique and for Paragonimus eggs using a concentration technique. Stool samples were subjected to the Ritchie technique. Schoolchildren provided a single stool sample, and samples were subjected to the Kato-Katz and an ether-concentration technique. A pre-tested questionnaire was administered to patients and schoolchildren to investigate food consumption habits. Additionally, between June 2009 and August 2010, shellfish were purchased from markets in Abidjan and Dabou and examined for metacercariae.

RESULTS

No human case of paragonimiasis was diagnosed. However, trematode infections were seen in 32 of the 272 shellfish examined (11.8%). Questionnaire results revealed that crab and pig meat is well cooked before consumption. Among the 278 patients with complete data records, 62 had tuberculosis, with a higher prevalence in males than females (28.8% vs. 13.9%, χ2 = 8.79, p = 0.003). The prevalence of helminths and intestinal protozoa was 4.6% and 16.9%, respectively. In the school survey, among 166 children with complete data records, the prevalence of helminths and intestinal protozoa was 22.3% and 48.8%, respectively. Boys had significantly higher prevalences of helminths and intestinal protozoa than girls. Hookworm was the predominant helminth species and Entamoeba coli was the most common intestinal protozoon species (13.8%).

CONCLUSIONS

Not a single case of Paragonimus was found in two high-risk groups of Côte d'Ivoire, most likely explained by food consumption habits. However, other helminth and intestinal protozoon infections were common.

Ziehl-Neelsen staining technique can diagnose paragonimiasis

BACKGROUND

We evaluated the Ziehl-Neelsen staining (ZNS) technique for the diagnosis of paragonimiasis in Laos and compared different modifications of the ZNS techniques.

METHODOLOGY

WE APPLIED THE FOLLOWING APPROACH: We (1) examined a paragonimiasis index case's sputum with wet film direct examination (WF) and ZNS; (2) re-examined stored ZNS slides from two provinces; (3) compared prospectively WF, ZNS, and formalin-ether concentration technique (FECT) for sputum examination of patients with chronic cough; and (4) compared different ZNS procedures. Finally, we assessed excess direct costs associated with the use of different diagnostic techniques.

PRINCIPAL FINDINGS

Paragonimus eggs were clearly visible in WF and ZNS sputum samples of the index case. They appeared brownish-reddish in ZNS and were detected in 6 of 263 archived ZNS slides corresponding to 5 patients. One hundred sputum samples from 43 patients were examined with three techniques, which revealed that 6 patients had paragonimiasis (13 positive samples). Sensitivity per slide of the FECT, ZNS and the WF technique was 84.6 (p = 0.48), 76.9 (p = 0.25) and 61.5% (p = 0.07), respectively. Percentage of fragmented eggs was below 19% and did not differ between techniques (p = 0.13). Additional operational costs per slide were 0 (ZNS), 0.10 US$ (WF), and 0.79 US$ (FECT). ZNS heated for five minutes contained less eggs than briefly heated slides (29 eggs per slide [eps] vs. 42 eps, p = 0.01). Bloodstained sputum portions contained more eggs than unstained parts (3.3 eps vs. 0.7 eps, p = 0.016).

CONCLUSIONS/SIGNIFICANCE

Paragonimus eggs can easily be detected in today's widely used ZNS of sputum slides. The ZNS technique appears superior to the standard WF sputum examination for paragonimiasis and eliminates the risk of tuberculosis transmission. Our findings suggest that ZNS sputum slides should also be examined routinely for Paragonimus eggs. ZNS technique has potential in epidemiological research on paragonimiasis.