Diseases: Cause, Carriers & Vaccines

A Snapshot of different diseases, their causes, the vectors who transmit these diseases and vaccines available against them.

Disease declared eradicated from country:

• Small Pox
• Guinea Worm

Diseases in Detail

Swine Flu:
Swine influenza, also called pig influenza, swine flu, hog flu and pig flu, is an infection caused by any one of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is any strain of the influenza family of viruses that is endemic in pigs. As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.

Ebola:

• Killed 700 ppl in 2014
• Democratic Republic of Congo. – a   village situated near the Ebola River, from which the disease takes its name.

Transmission
Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals. In Africa, infection has been documented through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest.
Ebola then spreads in the community through human-to-human transmission, with infection resulting from direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and indirect contact with environments contaminated with such fluids
The Ebola virus is not airborne,
EVD is a severe acute viral illness often characterized by the sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.
Those who fared best sought immediate medical attention and got supportive care to prevent dehydration even though there is no specific treatment for Ebola itself.
No vaccine as such.

SARS- CoV

MERS- CoV

The Middle East respiratory syndrome coronavirus (MERS-CoV), also termed EMC/2012 (HCoV-EMC/2012), is positive-sense, single-stranded RNA novel species of the genus Betacoronavirus.

• ISDP: Integrated disease surveillance programme

AIDS

Truvada

• World’s first Oral pill  to prevent HIV
• Developed by: Gilead Sciences.
• Made of two anti-reteroviral drugs:  1) Tenofovir and 2) Emtricitabine
• Given approval by US FDA.

AIDS treatment program in India:

1. The eligibility for receiving ART (Anti-Retroviral Therapy) has been revised from CD4 level of 350 to 500 in the  National AIDS Control Programme Phase IV (NACP IV)
2. CD4 refers to the cells that send signals to activate body’s immune response when they detect “intruders,” like viruses or bacteria
3. A normal CD4 count ranges from 500–1,000 cells/mm3. (pehle 350 ke neche ilaaj chalu karte they but ab 500 ke neeche jane par bhi kar paa rahe hain)

While there are many different types of T-cells, these particular cells(CD4) have a specific receptor site on their surface called the CD4 receptor site. HIV uses this particular receptor to latch on to the T-cell, making it a prime target for infection.
HIV hides in a state of hibernation in CD4 cells, an essential part of the immune system. Yet CD4 cells are unable to fight HIV themselves — that role lies with the immune system’s killer T-cells.
But because killer T-cells can’t detect the HIV hidden within CD4 cells, they are unable to attack and eliminate it from the body. While HIV patients on antiretroviral drug treatment often go on to have undetectable levels of HIV in their system, it is never eliminated.

 Filariasis

• Parasitic disease transmitted by blood -feeding arthropods, mainly black flies and mosquitoes.
• Most cases of filaria are caused by the parasite known asWuchereria bancrofti.
• Depending on the area which the worms affect, filariasis is classified as–
  • Lymphatic filariasis (Elephantiasis)– which affects the lymphatic system, including the lymph nodes. 
  • Subcutaneous filariasis– which affects the subcutaneous layer of the skin.
  • Serous cavity filariasis– which affects the serous cavity of the abdomen.
• No symptoms in the initial stage, therefore, most people initially are not aware.

A.1. Lymphatic filariasis (LF), commonly known as elephantiasis

• Usually acquired in childhood. In the early stages, there are no symptoms.
• In the adult stage, filarial worms live in the vessels of the lymphatic system. Lymphatic system is the network of lymph nodes and lymph vessels that maintains the fluid balance between the tissues and the blood which is an essential element of the body’s immune defense system.
• The persons having circulating microfilariae are outwardly healthy but transmit the infection to others through mosquitoes.
  The persons with chronic filarial swellings suffer severely from the disease but no longer transmit the infection.
• In India, 99.4% of the cases are caused by the species – Wuchereria bancrofti whereas Brugia malayi is responsible for 0.6% of the problem.
• Lymphatic filariasis is transmitted through mosquito bites. Affected person—mosquito bite—new person thru bite.
• Lymphatic filariasis is a leading cause of permanent and long-term disability worldwide.
• Drug given during MDA(Mass Drug Administration): DEC (Diethylcarbamazine citrate tablets).

Tuberculosis:

Vaccine: BCG: Bacillus Calmette–Guérin, that is prepared from a strain of the attenuated (weakened) live bovine tuberculosis bacillus, Mycobacterium bovis.
Two Types

• Multi-drug-resistant tuberculosis (MDR-TB) is defined as tuberculosis that is resistant to at least isoniazid (INH) and rifampicin (RMP),the two most powerful first-line treatment anti-TB drugs.
  • Treatment: Dot plus.

• Extensively drug resistant TB(XDR- TB)–
  • Risorin

• Project Axshya is a civil society initiative to make India TB-free. Bulgum Bhai (Mr.Sputum) is their mascot

• CSIR is developing this new Anti-TB drug:

• GeneXpert/ CBNAAT?
• Problem with MDR-TB= it takes almost 8 weeks, for doctor to diagnose this disease.
• GeneXpert/ CBNAAT is the latest device that can diagnose this MDR-TB in just two hours.

Leprosy:

• At highest risk are those living in areas with polluted water and poor diet or people suffering from diseases that compromise immune function.

Polio

The virus: Polio is caused by a human enterovirus called the poliovirus. Wild polioviruses are those that occur naturally.

• The poliovirus consists of an RNA genome enclosed in a protein shell called a capsid.
• There are three serotypes of wild poliovirus – type 1, type 2, and type 3 – each with a slightly different capsid protein.
• The virus invades the nervous system, causing paralysis in one out of every 200 children.
• Type 2 poliovirus has been eliminated in the wild – the last wild type 2 poliovirus was detected in India in 1999.
• In this final stage of polio eradication, only type 1 and type 3 wild poliovirus continue to circulate in endemic areas. Both are highly infectious and both cause paralytic polio. Type 1 is the most pervasive strain of poliovirus and type 3 is at very low levels.
• 2012: India se both eliminated.
• Vaccines:
  • Oral polio vaccine (OPV)
  • Monovalent oral polio vaccines (mOPV1 and mOPV3)
  • Bivalent oral polio vaccine (bOPV)
  • Inactivated polio vaccine (IPV)
  • tOPV(trivalent OPV)

Acute flaccid paralysis (AFP)

• Happens mostly among children under fifteen years of age are reported and tested
• Cause: wild poliovirus (type 1/3) or vaccine-derived or non-polio pathogens-enteroviruses
• No child in India has been diagnosed with polio for nearly two years now and all the indications are that the virus responsible for it is no longer circulating here.
• However, the country’s polio surveillance system has indicated a sharp increase during recent years in the number of non-polio AFP cases.
• most of the country’s non-polio AFP cases occur in just two States — Bihar and Uttar Pradesh. cases of children with non-polio AFP were not being monitored by either the polio eradication programme or the larger state health care system.
• As a result, there is no clear picture of what was causing the AFP, the kind of diseases these children displayed, or how many of them were seriously affected
• Type 1 & Type 3  eliminated in India
• Type 2 currently active [Vaccine- Derived Poliovirus (VDPV)]

Type 2: Vaccine-derived polioviruses (VDPVs)

• These are rare strains of poliovirus that have genetically mutated from the strain contained in the oral polio vaccine.
• Use of the oral polio vaccine in routine immunization programmes will therefore be phased out to eliminate the rare risks posed by vaccine-derived polioviruses.
• Instead use of Inactivated polio vaccine (IPV)

Kala Azar 

• Also called as visceral leishmaniasis
• Cause: Protozoa: Parasite: Leishmania, Vector – Sand Fly

Malaria:

The population residing in areas below 5000 ft. of sea level is prone to malaria as these areas have potential for malaria vector breeding. It is a fact that certain tribal groups are less prone to malaria infection.
Cause: Protozoa- plasmodium – P. falciparum and P. vivax, carried by female anopheles mosquitoes.
Disease Management:

• By using Rapid Diagnosis Test at peripheral institutions & by volunteers like ASHA’s and complete treatment with Artesunate Combination Therapy (ACT) for Pf cases.
• Strengthening of referral services.
• Epidemic preparedness and rapid response.

Integrated Vector Management :

• Indoor Residual Spraying in selected high risk areas
• Use of Insecticide treated bed nets & Long Lasting Insecticidal Nets in highly endemic areas.
• Larviciding by using anti larvals, larvivorous fishes and environmental management means.

Supportive Interventions:

• Behavior Change Communication
• Public Private Partnership & Inter-sectoral convergence
• Human Resource Development through capacity building
• Operational research including studies on drug   resistance and  insecticide

The Government of India provides technical assistance and logistics support including anti malaria drugs, DDT, larvicides etc. under the National Vector Borne Disease Control Programme (NVBDCP).

Anthrax

What causes anthrax?

• The agent of anthrax is a bacterium called Bacillus anthracis.

How is anthrax contracted?
Anthrax can infect humans in three ways.

• The most common is infection through the skin, which causes an ugly sore that usually goes away without treatment.
• Humans and animals can ingest anthrax from carcasses of dead animals that have been contaminated with anthrax.
• The most deadly form is inhalation anthrax. If the spores of anthrax are inhaled, they migrate to lymph glands in the chest where they proliferate, spread, and produce toxins that often cause death.

• Anthrax is treated by antibiotics.
• Anthrax can be prevented.

Parkinson’s Disease

Parkinson’s disease (PD also known as idiopathic or primary parkinsonism, hypokinetic rigid syndrome/HRS, or paralysis agitans) is a degenerative disorder of the central nervous system. The motor symptoms of Parkinson’s disease result from the death of dopamine-generating cells in the substantia nigra, a region of the midbrain; the cause of this cell death is unknown. Early in the course of the disease, the most obvious symptoms are movement-related; these include shaking, rigidity, slowness of movement and difficulty with walking and gait. Later, thinking and behavioral problems may arise, with dementia commonly occurring in the advanced stages of the disease, whereas depression is the most common psychiatric symptom. Other symptoms include sensory, sleep and emotional problems. Parkinson’s disease is more common in older people, with most cases occurring after the age of 50.

Brain Stem Death:

1. In India, the stage at which all functions of the brain stem have permanently and irreversibly ceased, such stage is called as ‘brain dead’.
2. In India, organs from a dead body can be removed only if the body is certified to be ‘brain dead’