World neglected tropical diseases (NTDs) day
Eminent Author, Medical Biochemist and Scientist, Technical Education consultant.
AGD Biomedicals (Pvt) LTD. Andheri East, Mumbai.
Importance of early diagnosis of neglected tropical diseases came into prominence recently after significant increases in the cases of Guillain-Barre syndrome (GBS) caused by primary infection of Campylobacter jejuni(1,4) and also by substantial increases in coinfections of dengue and chikungunya cases with malaria in India and other Asian countries(2,3). Reliable diagnosis of neglected tropical diseases is possible by fourth generation routine IVD clinical laboratory tests (Refer to Case study 1 and 2). However, accurate diagnosis of NTDs is not achieved in many cases due to inappropriate ways of selection of tests, specimen collection and follow up procedures. Latest devised fifth generation point-of-care tests (POCT) based on rapid immunochromatographic test (ICT) principles are extremely useful for a fast diagnostic outcome(5,6,7). Persons affected by NTDs also suffer from long-term secondary diseases, which cause decreased physical fitness, work productivity and additional financial burden due to prolonged medical Treatments(1,4,8,10)(Refer to case studies 1 and 2). With increased use and easy access to POCT technologies, reduction in NTD burden could indirectly promote economic development(6).
Q1. What are neglected tropical diseases (NTDs)?
ANS: Neglected Tropical Diseases (NTDs) are endemic among underprivileged populations, due to the unavailability or inadequate clinical laboratory test facilities(8).
Q2. What are the major NTDs affecting Indian population?
ANS: The major NTDs in India: Ascariasis, Hookworm disease, Trichuriasis, Dengue, Lymphatic Fileriasis (LF), Trachoma, Cysticercosis, Leprosy, Cystic echinococcosis, Visceral leishmaniasis, and Rabies(8).
Q3. What is the prevalence of NTDs in India and in the world?
ANS: It is estimated that NTDs in the world affect more than 1 billion people, while the number of people requiring NTD interventions (both preventive and curative) is about 1.6 billion(8). According to the latest study, India experiences the world’s largest absolute burden (about 20-30%) of at least 11 major NTDs(8).
Q4. What is Guillain-Barre syndrome (GBS)?
ANS: Guillain-Barre syndrome (GBS) is a neurological disorder, a secondary clinical condition, caused by primary bacterial infection such as Campylobacter jejuni, Mycoplasma pneumonia or by a viral infection such as COVID 19, Cytomegalovirus, Epstein-Barr virus, etc. In GBS antibodies produced against the microbial infection also attack patient’s neurological system. The patient suffers from severe pain, sensation changes, difficulty in walking, swallowing, speaking, breathing, coordination, affected vision, abnormal heart rate, increase in blood clots, low blood pressure, diarrhea, etc. and in severe cases, paralysis.
Q5. What are the routine IVD laboratory tests useful to detect NTDs?
ANS: The routine IVD laboratory tests: Complete hemogram (CBC), POCT multi-strip tests and routine feces examination.
Q6. What is the importance of complete hemogram (CBC) test in the detection of NTDs?
ANS: Complete hemogram gives the following various diagnostic advantages about NTDs(11):
- Significant decrease in platelets may be seen in dengue, malaria, chikungunya and leptospirosis.
- Significant decrease in blood hemoglobin is observed in infections such as malaria, hookworm, Helicobacter pylori, etc.
- Microscopic examination of stained blood (collected during fever) smear can detect malarial parasites, microfilariae, leishmania and trypanosoma organisms.
Q7. What is the importance of POCT dip-sticks (multi-strip) and routine examination of feces in the detection of NTDs?
ANS: POCT dip-sticks (multi-strip) can detect occult blood in feces in one minute, which gives idea about gastro-intestinal microbial infections leading to intestinal bleeding, as well as worm infestations leading to intestinal bleeding. Microscopic examination of feces can detect Ameba, Giardia, Round worm, Hook worm, Whip worm, Strongyloides, and Platyhelminth infections.
Q8. What are the latest innovations in IVD that could significantly impact the monitoring and management of IVDs?
ANS: Latest Fifth-generation Rapid Immunographic Test (ICT) cards can detect NTDs such as malaria, dengue, chikungunya, leptospirosis, etc., in 2-3 minutes at patient bedside(1,2,3). Once diagnosis of primacy disease is known early, secondary diseases could be cured early with effective therapy.
Q9. How does timely detection of NTDs through IVD impact patient outcomes and overall healthcare costs?
ANS: The following Case studies give ideas on how these patients suffered for several months, before a correct diagnosis was made about their respective sickness. Apart from prolonged suffering with health-related issues, there was substantial financial loss and time:
CASE STUDY 1
A 46-year-old male presented with fever, chills, headache, myalgia, bleeding of gums and deep bone pain. His hemogram indicated a significant decrease in platelets. Blood smears were prepared (during fever), and Field stained observations under the microscope did not show the presence of malarial parasites on two consecutive days.
| PARAMETER | VALUE | REFERENCE RANGE (NORMAL RANGE) |
| Complete Blood Count (CBC) | ||
| Hemoglobin | 13.2 g | 13-17 g |
| Total WBC count | 7,800 per µl | 5000-10,000 per µl |
| Differential WBC count | ||
| Neutrophils | 64% | 40-75% |
| Lymphocytes | 32% | 20-45% |
| Eosinophils | 04% | 1-4 % |
| Red blood cell indices | ||
| (MCV, MCH, MCHC) | Normal findings | |
| Platelet count | 55,000 per µl | |
According to the symptoms and history of the patient, following additional tests were performed:
- Dengue NS1 Ag assay: Positive
- Dengue IgM: Positive
- Dengue IgG: Negative
- Chikungunya virus nucleic acid by RT-PCR test: Negative
Note :
- Patient was suffering from Dengue fever. Malarial parasites and Chikungunya virus were not detected and the infection was primary since Dengue IgM was positive and Dengue IgG was negative.
- Patient suffered from muscle and joint pain for long time and financial loss incurred during treatment and recovery.
- Appropriate preventive measures by mosquito control could have been used effectively (using mosquito repellents, nets and fogging) and water logging (to avoid mosquito breeding) in areas near house and building.
- Severe dengue is a medical emergency; due to very low blood platelets, low blood pressure, hypovolemic shock and failure of various organs such as kidneys, liver and heart ultimately leading to death, if not treated in time.
CASE STUDY 2
A 27 year-old-woman presented with weakness, fatigue, loss of weight, abdominal pain, occasional diarrhea, palpitations, and dyspnea on exertion. Her blood histogram and other laboratory test reports were as follows
| PARAMETER | VALUE | REFERENCE RANGE (NORMAL RANGE) |
| Complete Hemogram | ||
| Hemoglobin | 6.8 g/dl | 12–16 g/dl |
| Total erythrocyte count | 3.03 X 1012/l | 4.3 ± 0.5 X 1012/l |
| Total leukocyte count | 5.1 X 109/l | 7.0 ± 3.0 X 109/l |
| Differential leukocyte count | ||
| Neutrophils | 32% | 40-75% |
| Lymphocytes | 62% | 20-45% |
| Eosinophils | 3% | 1-4 % |
| Monocytes | 01% | 2–8 % |
| Stained peripheral blood smear Microscopic observations: | ||
| Hypochromia | +++ | Normal cells |
| Microcytosis | ++ | Normal cells |
| Anisocytosis | +++ | Normal cells |
| PCV | 21% | 36–48% |
| MCV | 71.7 fL | 82–92 fL |
| MCH | 19.1 pg | 27–32 pg |
| MCHC | 26.7 % | 32–36 % |
| RDW- CV | 16.1 | 12–14 |
| Platelet count | 177 X 109/l | 150–400 X 109/l |
NOTE:
- The complete hemogram report indicated ‘Hypochromic microcytic Anemia’ on the basis of low values of Hb, RBC count, PCV, MCV, MCH, MCHC, and high RDW.
- After two months of treatment to improve blood hemoglobin, no significant improvement in blood hemoglobin was observed. Routine feces examination was prescribed. The following were main findings –
ROUTINE FECES EXAMINATION:
| PARAMETER | VALUE | REFERENCE RANGE (NORMAL RANGE) |
| Occult blood | Present, ++ | (occult blood is absent in a normal feces specimen) |
| Microscopic examination | Ova of hook worm were detected |
NOTE:
- Due to hook worm infection, continuous bleeding from small intestine, blood hemoglobin level remained low.
- Blood hemoglobin level of the patient improved, after specific deworming treatment.
Q10. What are the various measures suggested to control NTDs
ANS: The following various measures are suggested:
- Use of safe drinking water and foods
- Practice of good hygiene and sanitation
- Control of spread of vectors such as mosquitoes, flies, worms, etc.
- Good education of veterinary public health that includes deworming and vaccination of domestic animals, periodic check-ups and food safety
- Effective use of Immunizations
- Snake bite prevention and management
- Stray dog sterilization
References
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