Uncovering Haemoprotozoan Pathogens in Bangladesh's Bats and Rodents
Under the cover of darkness in Bangladesh's rural landscapes, creatures of the night—bats and rodents—go about their lives, unaware they may be carrying invisible passengers.
These are not the viruses that have dominated headlines in recent years, but a different class of pathogens altogether: haemoprotozoan parasites that invade blood cells, causing silent infections that ripple through ecosystems. While much scientific attention has focused on famous viruses like Nipah carried by fruit bats, the story of haemoprotozoa in Bangladesh's wildlife remains largely untold, representing a critical gap in our understanding of disease ecology.
Understanding wildlife parasites helps prevent disease transmission to humans and livestock
Bats play crucial roles in pollination and seed dispersal while potentially harboring pathogens
Haemoprotozoan parasites are microscopic organisms that infect the blood cells of vertebrates. The name itself reveals their nature: "haemo" meaning blood, and "protozoa" referring to single-celled organisms. These parasites are more than just scientific curiosities—they're efficient survivors that have evolved complex life cycles often involving multiple hosts and transmission vectors.
These parasites invade and destroy red blood cells, causing the disease known as babesiosis. They're often transmitted by ticks.
Rather than red blood cells, these target white blood cells or platelets. They're responsible for anaplasmosis.
Similar to Babesia but with more complex biological cycles involving both blood cells and lymph cells.
| Parasite Type | Primary Target in Blood | Main Vector | Disease Caused |
|---|---|---|---|
| Babesia species | Red blood cells | Ticks | Babesiosis |
| Anaplasma species | White blood cells | Ticks | Anaplasmosis |
| Theileria species | Lymphocytes & red blood cells | Ticks | Theileriosis |
| Trypanosoma species | Various blood components | Biting flies, kissing bugs | Trypanosomiasis |
Bangladesh's tropical climate, characterized by high temperatures and humidity, provides the perfect environment for the ticks and other arthropods that transmit these parasites.
Research has shown that the prevalence of haemoprotozoan diseases in Bangladesh follows seasonal patterns, with infections peaking during the warmer, wetter months 4 .
Bangladesh is home to a remarkable diversity of bats, with at least 31 confirmed species representing 8 different families 5 .
While previous research in Bangladesh has primarily focused on bats as carriers of viruses like Nipah virus 2 and coronaviruses 3 , their potential as reservoirs for haemoprotozoan parasites remains largely unexplored.
Bats and rodents are captured using mist nets, harp traps, or live traps. Blood samples are then collected through venipuncture and preserved with anticoagulants.
Initial screening involves creating thin blood smears on microscope slides. These are stained with Giemsa stain to make parasites visible under magnification.
PCR amplifies specific DNA sequences unique to each parasite, enabling detection even when only a few parasites are present in the sample.
| Method | How It Works | Key Advantage | Limitation |
|---|---|---|---|
| Light Microscopy | Visual identification of parasites in stained blood smears | Low cost, rapid results | Misses low-level infections |
| Polymerase Chain Reaction (PCR) | Amplifies parasite-specific DNA sequences | High sensitivity, species identification | Higher cost, requires specialized equipment |
| Serological Tests | Detects antibodies against parasites | Identifies past exposures | Cannot detect active infections |
| DNA Sequencing | Determines genetic code of specific genes | Precise species identification | Time-consuming and expensive |
| Host Species | Number Sampled | Overall Infection Rate | Babesia Prevalence | Anaplasma Prevalence | Theileria Prevalence | Mixed Infections |
|---|---|---|---|---|---|---|
| Pteropus giganteus (Fruit bat) | 105 | 8.6% | 3.8% | 4.8% | 0.0% | 1.0% |
| Megaderma lyra (Insectivorous bat) | 97 | 12.4% | 5.2% | 6.2% | 1.0% | 1.0% |
| Rodents (combined species) | 143 | 15.4% | 7.0% | 5.6% | 2.8% | 2.1% |
Capture bats without harm for ethical specimen collection
Isolate genetic material from blood samples for molecular analysis
Enzymes and buffers for DNA amplification to detect parasite DNA
Determines genetic code of PCR products for definitive species identification
For Bangladesh, where livestock contributes approximately 1.78% to the national GDP and provides employment for nearly 20% of the rural population 9 , understanding haemoprotozoan diseases is economically significant. Previous research has documented that tick-borne haemoprotozoan infections can cause substantial economic losses 8 .